Merge release/v1.7.x into main for v1.8.0

main had fallen a full feature generation behind: 13739 lines and 29 files
that main did not contain at all (the whole Lua plugin mechanism, the billing
package, stats_period, plugins_api, docs/plugins.md). v1.7.x contains
everything main has and nothing main lacks, so this is a one-way merge rather
than two divergent lines.

Eight conflicts, each read before resolving — the script that does it lives at
.probe/resolve_merge_conflicts.py and aborts rather than guess:

* cmd/gui/package.json, cmd/gui/package-lock.json — main already carries 1.8.0
  (4b37e1a); the release line carries 1.7.6. Kept 1.8.0. Taking 1.7.6 would
  ship tag v1.8.0 next to a manifest claiming 1.7.6.
* packaging/config.example.yaml (2 hunks) — release side is a superset both
  times: it documents the `auto:` field, and it replaces the older one-line
  runtime_file note with a paragraph that also states where templates and
  deleted-markers live and warns that the AUTO chain, gateway keys and sources
  are in config.yaml. HEAD's wording is strictly less.
* internal/config/config.go, internal/core/core.go, internal/gateway/api.go,
  internal/gateway/apiv1.go, internal/gateway/stats.go (6 hunks) — HEAD is
  zero-length in every one and the release side is the new code: BillingDSL
  types, applyBillingDSL, the pointer-semantics source upsert, the
  optional_fields doc string, the AUTO chain-walk field. The resolver asserts
  the empty-HEAD property instead of assuming it.

Verified before committing: no residual conflict markers, both manifests read
1.8.0, `go build -tags luajit ./...` clean, `go test -tags luajit ./...` all nine
packages pass.

.gitignore

@@ -26,3 +26,7 @@ cmd/gui/dist/
 
 # local design/working notes (not part of the shipped repo)
 /plan.md
+
+# scratch build/probe dirs used while debugging (GOTMPDIR, throwaway binaries)
+.build-work/
+.probe/

cmd/gui/main.js

@@ -671,6 +671,78 @@ ipcMain.handle(
   (e) => !!BrowserWindow.fromWebContents(e.sender)?.isMaximized(),
 );
 
+// ---- plugin management over IPC -------------------------------------------
+//
+// The renderer cannot call the embedded core directly: it has no key and no
+// network identity, and the core binds a loopback port that only the main
+// process knows about. So every plugin action is proxied through the main
+// process, which already knows how to obtain the admin key (unsealViaCore).
+//
+// The proxy is deliberately a raw (method, path, body) pass-through rather than
+// a fixed set of commands. A fixed set would have to be extended for every new
+// plugin endpoint, and the one thing worse than "no button for this" is "a
+// button that silently does nothing" — with a pass-through the renderer can talk
+// to any /api/plugins route the core grows, and the path is validated here so
+// this channel cannot be used to reach arbitrary endpoints.
+function pluginProxy(req) {
+  const { method, path, body } = req || {};
+  const M = ["GET", "POST", "PUT", "DELETE"];
+  if (!M.includes(method)) throw new Error("bad method: " + method);
+  // The path must stay inside the plugin namespace. A prefix check alone would
+  // still allow /api/plugins/../keys, so reject any traversal outright.
+  if (typeof path !== "string" || !path.startsWith("/api/plugins")) {
+    throw new Error("path must start with /api/plugins");
+  }
+  if (path.includes("..") || path.includes("\\")) {
+    throw new Error("path traversal rejected");
+  }
+  const key = unsealViaCore();
+  if (!key) throw new Error("no admin key available yet");
+  return new Promise((resolve, reject) => {
+    const u = new URL(embeddedBaseUrl() + path);
+    const data = body == null ? null : JSON.stringify(body);
+    const headers = { Authorization: "Bearer " + key };
+    if (data) {
+      headers["Content-Type"] = "application/json";
+      headers["Content-Length"] = Buffer.byteLength(data);
+    }
+    const r = http.request(
+      {
+        hostname: u.hostname,
+        port: u.port,
+        path: u.pathname + u.search,
+        method,
+        headers,
+      },
+      (res) => {
+        let raw = "";
+        res.setEncoding("utf8");
+        res.on("data", (c) => (raw += c));
+        res.on("end", () => {
+          let parsed = null;
+          try {
+            parsed = raw ? JSON.parse(raw) : null;
+          } catch (e) {
+            parsed = { raw };
+          }
+          if (res.statusCode >= 400) {
+            const msg =
+              (parsed && parsed.error && parsed.error.message) ||
+              "HTTP " + res.statusCode;
+            reject(new Error(msg));
+            return;
+          }
+          resolve(parsed);
+        });
+      },
+    );
+    r.on("error", reject);
+    if (data) r.write(data);
+    r.end();
+  });
+}
+
+ipcMain.handle("plugins:proxy", (_e, req) => pluginProxy(req));
 ipcMain.handle("core:state", () => ({
   running: coreStarted() && coreReady,
   ready: coreReady,

cmd/gui/package-lock.json

@@ -582,7 +582,7 @@
       }
     },
     "node_modules/@peculiar/webcrypto": {
-      "version": "1.7.1",
+      "version": "1.7.5",
       "resolved": "https://registry.npmjs.org/@peculiar/webcrypto/-/webcrypto-1.7.1.tgz",
       "integrity": "sha512-ODOov0sGMJMf3jPonOkgGqPknTsu+DdQ7kD++gz8aI+aFMOMHFbWAA2taqXXVTdP+OTOQR/znGvSpmkeI0WTYQ==",
       "dev": true,
@@ -3335,7 +3335,7 @@
       }
     },
     "node_modules/resedit": {
-      "version": "1.7.2",
+      "version": "1.7.5",
       "resolved": "https://registry.npmjs.org/resedit/-/resedit-1.7.2.tgz",
       "integrity": "sha512-vHjcY2MlAITJhC0eRD/Vv8Vlgmu9Sd3LX9zZvtGzU5ZImdTN3+d6e/4mnTyV8vEbyf1sgNIrWxhWlrys52OkEA==",
       "dev": true,

cmd/gui/preload.js

@@ -16,6 +16,13 @@ contextBridge.exposeInMainWorld("modelrouter", {
     key: () => ipcRenderer.invoke("core:key"),
     onState: (cb) => ipcRenderer.on("core:state", (_e, d) => cb(d)),
   },
+  plugins: {
+    // Raw pass-through to the embedded core's /api/plugins surface. The main
+    // process validates the path and attaches the admin key; the renderer never
+    // sees either.
+    request: (method, path, body) =>
+      ipcRenderer.invoke("plugins:proxy", { method, path, body }),
+  },
   settings: {
     get: () => ipcRenderer.invoke("settings:get"),
     set: (patch) => ipcRenderer.invoke("settings:set", patch),

cmd/gui/renderer/app.js

@@ -155,6 +155,7 @@ async function openSettings() {
   $("#set-tray").checked = !!state.settings.minimizeToTray;
   $("#settings-overlay").style.display = "flex";
   renderRail();
+  loadPlugins();
 }
 function closeSettings() {
   $("#settings-overlay").style.display = "none";
@@ -182,6 +183,122 @@ async function saveSettings() {
   }
 }
 
+// esc / escAttr escape text for innerHTML. The WebUI has its own copies; the
+// shell needs its own because renderer/app.js is a separate document that
+// never loads index.html's script.
+function esc(s) {
+  return String(s == null ? "" : s).replace(
+    /[&<>"']/g,
+    (c) => ({ "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;" })[c],
+  );
+}
+function escAttr(s) {
+  return esc(s).replace(/`/g, "&#96;");
+}
+
+// ===== plugin management =====
+//
+// The desktop shell manages plugins through the embedded core's /api/plugins
+// surface, proxied over IPC (see plugins:proxy in the main process). The
+// renderer never holds the admin key.
+//
+// Scope note: the desktop build has no plugin_dir configured by default, so this
+// panel normally reports "plugins disabled" with the one-line fix. That is a
+// deliberate state, not an error — the packaged profile is a per-user directory
+// and seeding a plugin tree into someone's home without asking would be rude.
+
+async function loadPlugins() {
+  const list = $("#pl-list");
+  const hint = $("#set-plugins-hint");
+  if (!list || !hint) return;
+  let j;
+  try {
+    j = await window.modelrouter.plugins.request("GET", "/api/plugins");
+  } catch (e) {
+    hint.textContent = "内核未就绪：" + e.message;
+    list.innerHTML = "";
+    return;
+  }
+  if (!j.plugin_dir) {
+    hint.innerHTML =
+      '未配置 <code>plugin_dir</code>，插件功能未启用。在 config.yaml 加一行后重启内核即可。';
+    list.innerHTML = "";
+    return;
+  }
+  const rows = j.on_disk || [];
+  const active = rows.filter((p) => p.loaded && !p.disabled).length;
+  const broken = rows.filter((p) => !p.loaded).length;
+  hint.textContent =
+    `${rows.length} 个插件 · ${active} 个启用中` +
+    (broken ? ` · ${broken} 个加载失败` : "");
+  list.innerHTML = rows.length
+    ? rows
+        .map((p) => {
+          const cls = !p.loaded ? "pl-broken" : p.disabled ? "pl-off" : "pl-on";
+          const label = !p.loaded
+            ? "加载失败"
+            : p.disabled
+              ? "已禁用"
+              : "启用中";
+          const btn = p.loaded
+            ? `<button class="ghost" data-act="toggle" data-name="${escAttr(
+                p.name,
+              )}" data-en="${p.disabled ? "1" : "0"}">${
+                p.disabled ? "启用" : "禁用"
+              }</button>`
+            : "";
+          const builtin = p.builtin
+            ? '<span class="pl-builtin">内置</span>'
+            : "";
+          return `<div class="pl-item ${cls}">
+            <div class="pl-head"><b>${esc(p.name)}</b>${builtin}<span class="pl-state">${label}</span></div>
+            ${p.description ? `<div class="pl-desc">${esc(p.description)}</div>` : ""}
+            ${p.error ? `<div class="pl-err">${esc(String(p.error).slice(0, 160))}</div>` : ""}
+            <div class="pl-acts">${btn}</div>
+          </div>`;
+        })
+        .join("")
+    : '<div class="pl-empty">插件目录为空</div>';
+  list.querySelectorAll('button[data-act="toggle"]').forEach((b) => {
+    b.onclick = () => togglePlugin(b.dataset.name, b.dataset.en === "1");
+  });
+}
+
+async function togglePlugin(name, disabled) {
+  try {
+    await window.modelrouter.plugins.request("PUT", `/api/plugins/${encodeURIComponent(name)}`, {
+      enabled: disabled,
+    });
+    toast(disabled ? `已禁用 ${name}` : `已启用 ${name}`);
+    await loadPlugins();
+  } catch (e) {
+    toast(e.message, true);
+  }
+}
+
+async function enableAllPlugins() {
+  let j;
+  try {
+    j = await window.modelrouter.plugins.request("GET", "/api/plugins");
+  } catch (e) {
+    return toast(e.message, true);
+  }
+  const off = (j.on_disk || []).filter((p) => p.loaded && p.disabled);
+  for (const p of off) {
+    try {
+      await window.modelrouter.plugins.request(
+        "PUT",
+        `/api/plugins/${encodeURIComponent(p.name)}`,
+        { enabled: true },
+      );
+    } catch (e) {
+      toast(`${p.name}: ${e.message}`, true);
+    }
+  }
+  toast(off.length ? `已启用 ${off.length} 个插件` : "没有处于禁用状态的插件");
+  await loadPlugins();
+}
+
 // ===== theme =====
 function applyTheme() {
   document.documentElement.dataset.theme = state.theme;
@@ -197,6 +314,10 @@ function init() {
   $("#tb-close").onclick = () => window.modelrouter.win.close();
   $("#tb-settings").onclick = openSettings;
   $("#rail-settings").onclick = openSettings;
+  const plReload = document.getElementById("pl-reload");
+  if (plReload) plReload.onclick = loadPlugins;
+  const plAll = document.getElementById("pl-toggle-all");
+  if (plAll) plAll.onclick = enableAllPlugins;
   $("#rail-autostart").onclick = toggleAutoStart;
   $("#rail-silent").onclick = toggleSilent;
   $("#rail-theme").onclick = () => {

cmd/gui/renderer/index.html

@@ -207,6 +207,15 @@
               ><input type="checkbox" id="set-tray" /> 关闭时最小化到托盘</label
             ><span class="hint">点关闭按钮隐藏到系统托盘</span>
           </div>
+          <div class="row">
+            <label>插件</label>
+            <span class="hint" id="set-plugins-hint">加载中…</span>
+          </div>
+          <div id="pl-list" class="pl-list"></div>
+          <div class="row actions">
+            <button class="ghost" id="pl-toggle-all">全部启用</button>
+            <button class="ghost" id="pl-reload">刷新</button>
+          </div>
           <div class="row actions">
             <button class="ghost" id="set-dir">打开数据目录</button>
             <button class="ghost" id="set-log">查看日志</button>

cmd/gui/renderer/style.css

@@ -596,3 +596,81 @@ html[data-theme="dark"] .overlay {
 #toast.err {
  border-color: var(--danger);
 }
+
+/* ===== plugin management panel =========================================
+ * The existing .ghost/.primary rules are scoped to `.form .actions`, so a
+ * button outside that selector gets browser defaults. The plugin rows live in
+ * their own list, hence their own rules — reusing a scoped class here would have
+ * produced unstyled buttons that still worked, which is the kind of thing that
+ * looks fine until someone themes the shell.
+ */
+.pl-list {
+ display: flex;
+ flex-direction: column;
+ gap: 8px;
+ margin: 8px 0 4px;
+}
+.pl-item {
+ border: 1px solid var(--line);
+ border-radius: 9px;
+ padding: 10px 12px;
+}
+.pl-item.pl-broken {
+ border-color: var(--danger, #d1435b);
+}
+.pl-head {
+ display: flex;
+ align-items: center;
+ gap: 8px;
+ font-size: 13px;
+}
+.pl-builtin {
+ font-size: 10px;
+ padding: 1px 6px;
+ border-radius: 999px;
+ background: var(--primary-50);
+ color: var(--primary-h);
+}
+.pl-state {
+ margin-left: auto;
+ font-size: 11px;
+ color: var(--muted);
+}
+.pl-item.pl-broken .pl-state {
+ color: var(--danger, #d1435b);
+}
+.pl-desc {
+ font-size: 12px;
+ color: var(--muted);
+ margin-top: 3px;
+}
+.pl-err {
+ font-size: 11px;
+ color: var(--danger, #d1435b);
+ margin-top: 4px;
+ word-break: break-word;
+}
+.pl-acts {
+ margin-top: 8px;
+ display: flex;
+ gap: 8px;
+}
+.pl-acts button {
+ padding: 5px 12px;
+ font-size: 12px;
+ border-radius: 7px;
+ border: 1px solid var(--line);
+ background: var(--bg-s2, #fff);
+ color: var(--fg, inherit);
+ cursor: pointer;
+ transition: all 0.15s;
+}
+.pl-acts button:hover {
+ border-color: var(--primary);
+ color: var(--primary-h);
+}
+.pl-empty {
+ font-size: 12px;
+ color: var(--muted);
+ padding: 10px 0;
+}

deploy.sh

@@ -301,6 +301,60 @@ verify_master_key() {
     return 1
 }
 
+# ---------- 适配器备份保留策略 ----------
+# 每次部署都新建一个 adapters.bak.<时间戳> 目录，而回滚只用到最近一次
+# （$BACKUP_BIN / $BACKUP_CONFIG 都是单文件覆盖）。多出来的目录从没人清理，
+# 实测线上已积累 71 个，/etc/llmsproxy 因此涨到 122M。
+#
+# 保留最近 KEEP_ADAPTER_BACKUPS 份足够回滚，同时给目录数设上限——否则
+# 一次误配置（比如 adapter_dir 指错）就可能在几秒内造出成百上千个目录。
+# 只删名字严格匹配 adapters.bak.<14位时间戳> 的目录，避免误伤人工放的目录。
+KEEP_ADAPTER_BACKUPS=5
+
+prune_adapter_backups() {
+    local base="/etc/llmsproxy"
+    [[ -d "$base" ]] || return 0
+
+    # 先按数量上限硬裁：即使时间戳排序失效也不会无上限增长。
+    local all
+    mapfile -t all < <(find "$base" -maxdepth 1 -type d -name 'adapters.bak.*' -printf '%f\n' | sort)
+    local cap=$((KEEP_ADAPTER_BACKUPS * 4))
+    if (( ${#all[@]} > cap )); then
+        warn "适配器备份目录有 ${#all[@]} 个（异常），裁到 $cap"
+        local i=0
+        for d in "${all[@]}"; do
+            i=$((i + 1))
+            # 从最旧的开始删（sort 后升序）。名字不规范的跳过不删。
+            if (( i <= ${#all[@]} - cap )); then
+                if [[ "$d" =~ ^adapters\.bak\.[0-9]{14}$ ]]; then
+                    rm -rf "${base:?}/$d"
+                else
+                    warn "跳过名字不规范的备份目录（不删）: $d"
+                fi
+            fi
+        done
+        mapfile -t all < <(find "$base" -maxdepth 1 -type d -name 'adapters.bak.*' -printf '%f\n' | sort)
+    fi
+
+    # 再按时间保留最近 KEEP_ADAPTER_BACKUPS 份（sort 后最新在末尾）。
+    local total=${#all[@]} i=0
+    for d in "${all[@]}"; do
+        i=$((i + 1))
+        # i <= total-KEEP 的是较旧的，要删。
+        if (( i <= total - KEEP_ADAPTER_BACKUPS )); then
+            if [[ "$d" =~ ^adapters\.bak\.[0-9]{14}$ ]]; then
+                rm -rf "${base:?}/$d"
+            else
+                warn "跳过名字不规范的备份目录（不删）: $d"
+            fi
+        fi
+    done
+
+    local left
+    left=$(find "$base" -maxdepth 1 -type d -name 'adapters.bak.*' | wc -l)
+    log "  适配器备份保留最近 $KEEP_ADAPTER_BACKUPS 份（当前剩 $left 个）"
+}
+
 # ---------- 同步适配器 ----------
 sync_adapters() {
     log "同步适配器"
@@ -318,6 +372,7 @@ sync_adapters() {
         cp -rf "$TARGET_ADAPTERS/"*.lua "$BACKUP_DIR/" 2>/dev/null || true
         log "  旧适配器已备份到 $BACKUP_DIR"
     fi
+    prune_adapter_backups
 
     cp -f "$SRC_ADAPTERS/"*.lua "$TARGET_ADAPTERS/"
     chmod 0644 "$TARGET_ADAPTERS/"*.lua

docs/git-workflow-en.md

@@ -15,7 +15,7 @@ deployable.
 |---|---|---|---|
 | Main | `main` | permanent | Only long-lived branch. Always deployable. Accumulates the next version. |
 | Feature | `feature/<desc>` | short (dev → merge → delete) | New features / ordinary fixes. Born from `main`, merged back into `main`. |
-| Release | `release/vX.Y.Z` | one version cycle | Cut from `main`, tagged for release. Version-specific hotfixes land here. |
+| Release | `release/vX.Y.x` | one version cycle | Cut from `main`, tagged for release. Version-specific hotfixes land here. |
 
 ## Change flow (important)
 
@@ -26,15 +26,21 @@ deployable.
                            │                        │
                            │ cut                    │ cut
                            ▼                        ▼
-                    release/v1.4.2            release/v1.4.3
+                    release/v1.6.x            release/v1.7.x
                            │                        │
-                    tag: v1.4.2               tag: v1.4.3
+                      tag: v1.6.0               tag: v1.7.6
                            │                        │
               hotfix ◄─────┘                hotfix ◄─────┘
                    │                              │
                    └── cherry-pick back ──────────┘
 ```
 
+The patch position in the branch name is a literal `x`, while the tag carries
+the concrete version: one `release/v1.7.x` can hold tags v1.7.0 … v1.7.6.
+Spanning several patches on a single minor branch is deliberate — patches are
+revisions of the same feature batch, hotfixes land on one branch, and back-port
+to main never has to resolve dependencies between several release branches.
+
 ### Key rules
 
 1. **main is always deployable**: never leave half-done work on `main`.
@@ -43,9 +49,9 @@ deployable.
    then `git merge --no-ff feature/xxx` (or squash) when done.
 3. **Release = cut a release branch from main + tag**:
    ```bash
-   git checkout -b release/v1.4.2 main
+   git checkout -b release/v1.7.x main
-   git tag -a v1.4.2 -m "ModelRouter v1.4.2"
+   git tag -a v1.7.0 -m "ModelRouter v1.7.0"
-   git push origin release/v1.4.2 v1.4.2
+   git push origin release/v1.7.x v1.7.0
    ```
    Build installers and upload the GitCode Release from this tag so the
    published state is exactly reproducible.
@@ -54,7 +60,7 @@ deployable.
    an already-released branch (unless you deliberately ship a minor revision).
 5. **Hotfixes MUST flow back to main**:
    ```bash
-   git checkout release/v1.4.2     # fix in the release branch
+   git checkout release/v1.7.x     # fix in the release branch
    git commit -m "fix: ..."
    git checkout main
    git cherry-pick <hotfix-commit> # and into main
@@ -67,12 +73,23 @@ deployable.
 When the next version ships, the previous release branch retires:
 
 - **Default: delete the remote release branch**
-  (`git push origin :release/v1.4.2`). All hotfixes were already
+  (`git push origin :release/v1.7.x`). All hotfixes were already
   cherry-picked into main, so main contains everything; no merge needed.
 - **Long-term maintenance** (e.g. an enterprise client pinned to an old
   version): keep the branch, accept only security fixes, keep the
   commit-then-cherry-pick loop.
 
+> **Where practice diverged from this section (checked 2026-10-01)**:
+> `release/v1.4.x` and `release/v1.5.x` still exist locally and on the remote,
+> so "retire the previous branch when the next version ships" was never
+> carried out. Keeping them is harmless (hotfixes were back-ported), but it
+> contradicts the rule above and makes a reader wonder whether they should be
+> there at all. **Feature branches, by contrast, are cleaned up**:
+> `feature/key-quota-control`, `feature/toolcall-id-sanitize`,
+> `feature/anthropic-usage-cache` and `feature/agentrouter-id-sanitize` were
+> deleted on 2026-10-01 after confirming with a per-commit `git patch-id`
+> comparison that their work had already landed in main.
+
 ## Explicit non-goals
 
 - **Never rebase main**: main's history stays append-only; anyone pulling gets
@@ -134,8 +151,8 @@ pain points:
 2. No feature branches meant two independent efforts could not proceed in
    parallel without colliding.
 
-With release branches: the published state = `release/vX.Y.Z` branch +
+With release branches: the published state = `release/vX.Y.x` branch +
-`vX.Y.Z` tag, exactly reproducible; hotfixes have a clear landing spot; main
+the concrete `vX.Y.Z` tag, exactly reproducible; hotfixes have a clear landing
-stays "latest + all fixes + deployable".
+spot; main stays "latest + all fixes + deployable".
 
 > 中文版见 [docs/git-workflow.md](git-workflow.md)。

docs/git-workflow.md

@@ -13,7 +13,7 @@ ModelRouter 采用 **GitHub Flow + 发布分支** 模型：`main` 是唯一长
 |---|---|---|---|
 | 主分支 | `main` | 永久 | 唯一长命分支。永远可部署。积攒下一个版本的功能。 |
 | 特性分支 | `feature/<描述>` | 短命（开发→合并即删） | 新特性 / 一般 bug 修复。从 `main` 开出，完成后合回 `main`。 |
-| 发布分支 | `release/vX.Y.Z` | 一个版本周期 | 从 `main` 分出，打 tag 发布。该版本生命周期内的 hotfix 都提交在此分支。 |
+| 发布分支 | `release/vX.Y.x` | 一个版本周期 | 从 `main` 分出，打 tag 发布。该版本生命周期内的 hotfix 都提交在此分支。 |
 
 ## 变更流向（重要）
 
@@ -24,15 +24,20 @@ ModelRouter 采用 **GitHub Flow + 发布分支** 模型：`main` 是唯一长
                            │                        │
                            │ 切出                   │ 切出
                            ▼                        ▼
-                    release/v1.4.2            release/v1.4.3
+                     release/v1.6.x            release/v1.7.x
                            │                        │
-                    tag: v1.4.2               tag: v1.4.3
+                      tag: v1.6.0               tag: v1.7.6
                            │                        │
               hotfix ◄─────┘                hotfix ◄─────┘
                    │                              │
                    └── cherry-pick 回 main ───────┘
 ```
 
+分支名里 patch 位是**字面的 x**，而 tag 打具体版本号：`release/v1.7.x` 这一条
+发布分支上的 tag 可以有 v1.7.0 … v1.7.6 多个。一条 minor 分支跨多个 patch 是
+刻意的：patch 是同一批功能的不同修订，hotfix 落在同一条分支上，回流 main 时
+也不必处理多条 release 分支之间的依赖。
+
 ### 关键规则
 
 1. **main 永远可部署**：不在 main 上留半成品。任何未完成的工作必须在特性分支上。
@@ -40,16 +45,16 @@ ModelRouter 采用 **GitHub Flow + 发布分支** 模型：`main` 是唯一长
    开发完 `git merge --no-ff feature/xxx` 或 squash 合回。
 3. **发布 = 从 main 切 release 分支 + 打 tag**：
    ```bash
-   git checkout -b release/v1.4.2 main
+   git checkout -b release/v1.7.x main
-   git tag -a v1.4.2 -m "ModelRouter v1.4.2"
+   git tag -a v1.7.0 -m "ModelRouter v1.7.0"
-   git push origin release/v1.4.2 v1.4.2
+   git push origin release/v1.7.x v1.7.0
    ```
    构建安装包、上传 GitCode Release 都基于这个 tag，保证可精确回溯发布态。
 4. **版本生命周期内只收该版本的 hotfix**：新特性一律并入 `main` 等下一个版本，
    绝不塞进已发布的 release 分支（除非主动选择在该版本内发次要版）。
 5. **hotfix 必须回流 main**：
    ```bash
-   git checkout release/v1.4.2     # 在发布分支提交修复
+   git checkout release/v1.7.x     # 在发布分支提交修复
    git commit -m "fix: ..."
    git checkout main
    git cherry-pick <hotfix-commit> # 回主分支
@@ -61,11 +66,20 @@ ModelRouter 采用 **GitHub Flow + 发布分支** 模型：`main` 是唯一长
 
 下一个版本发布时，上一个 release 分支退役：
 
-- **默认：直接删除远端 release 分支**（`git push origin :release/v1.4.2`）。
+- **默认：直接删除远端 release 分支**（`git push origin :release/v1.7.x`）。
   因为 hotfix 都已逐个 cherry-pick 回 main，main 已包含全部修复，无需再合并。
 - **如需要长期维护旧版**（例如企业大客户卡在旧版本）：保留分支，仅 stopship 接受
   该版本的安全修复，继续走「提交 + cherry-pick 回 main」循环。
 
+> **实践与本节的历史出入（2026-10-01 核对）**：`release/v1.4.x` 与 `release/v1.5.x`
+> 至今仍在本地与远端，说明"下一个版本发布就删上一个分支"实际没有执行。
+> 保留无害（hotfix 已回流），但它与上面写的规则不一致，读文档的人会以为
+> 这些分支不该存在。**特性分支则确实在清理**：`feature/key-quota-control`、
+> `feature/toolcall-id-sanitize`、`feature/anthropic-usage-cache`、
+> `feature/agentrouter-id-sanitize` 四个分支在 2026-10-01 删除——它们的工作
+> 早已全部进入 main（逐提交用 `git patch-id` 比对确认），留着只是给下个版本
+> 制造 cherry-pick/merge 陷阱。
+
 ## 明确不做的事
 
 - **不 rebase main**：`main` 的历史保持追加式，任何人拉取后 `git pull` 都得到直接可用的历史。

docs/plugins.md

@@ -0,0 +1,507 @@
+# 插件系统（Plugin System）
+
+> **English**: this document is the reference for writing ModelRouter plugins.
+> The Chinese version is the primary one; section titles map 1:1.
+
+ModelRouter 的插件是**单个 `.lua` 文件**，放在 `config.yaml` 的 `plugin_dir` 目录里。
+插件能做两件事：
+
+1. **挂钩子**：在请求流水线的若干 stage 上注册回调，看到每个请求的完整信息，
+   并可以把结果累加进自己的状态。
+2. **贡献界面**：在启动时返回 HTML / CSS / JS，由内核注入 WebUI——可以是一整个
+   新页面，也可以是往现有页面里追加一个组件。
+
+两者互相独立：只想统计请求数的插件不必碰界面；只想加个仪表盘的插件不必碰钩子。
+
+---
+
+## 1. 快速上手
+
+一个最小的插件：
+
+```lua
+-- plugins/hello.lua
+local plugin = {
+  name = "hello",
+  version = "1.0.0",
+  description = "示例插件",
+  author = "you",
+}
+
+-- 声明钩子
+plugin.hooks = {
+  request_end = "on_request_end",
+}
+
+-- 钩子实现
+function plugin.on_request_end(payload)
+  -- payload 是解码后的 table，不是 JSON 字符串
+  log("info", string.format("%s via %s: %d prompt tokens",
+    payload.model, payload.source, payload.prompt_tokens or 0))
+  return nil  -- 最后一个 stage 没有下游，return 无意义
+end
+
+-- 贡献界面
+plugin.ui = {
+  page = {
+    page_id = "hello",     -- kebab-case
+    title = "Hello",
+    icon = "👋",
+    order = 90,            -- 侧栏排序
+    mount = [[<div id="hello">hello</div>]],
+  },
+}
+
+return plugin   -- 必须返回一个 table
+```
+
+放进 `plugin_dir` 后重启即生效。`GET /api/plugins` 确认它被加载了。
+
+---
+
+## 2. 加载与生命周期
+
+```
+core.New
+  └─ lua.NewVM(adapter_dir).Start()        适配器状态
+  └─ lua.NewPlugins(vm, plugin_dir)
+       ├─ SeedBundled()                    仅当目录不存在时写入内置插件（目前是 billing）
+       └─ LoadDir()                        按文件名字典序逐个加载
+```
+
+**加载失败不影响网关启动。** 一个语法错误的插件会被记录在 `GET /api/plugins`
+的 `error` 字段里，永远不会被调用。这与适配器一致，但理由更强：插件是可选的
+第三方扩展，因为一个 `.lua` 打错字就让网关起不来是错误的取舍。
+
+**目录一旦存在就是权威的。** 与适配器同规则：首启会 seed 内置插件，之后目录里
+的文件说了算，删除或编辑内置插件都是真实生效的操作。
+
+### 2.1 热更新
+
+| 方式 | 效果 |
+|---|---|
+| `POST /api/plugins {name, code}` | 写文件 + 立即加载新版本（旧的 Lua 状态被关闭重建，**累计量清零**） |
+| `DELETE /api/plugins/{name}` | 删文件 + 卸载 |
+| 改文件后 `POST` 同名 | 同上 |
+
+改文件但**不** POST，需要重启才生效。
+
+---
+
+## 3. 流水线 stage
+
+一个请求依次经过三个 stage。插件可以为任意 stage 注册钩子；未注册的 stage
+被忽略，所以插件不会因为网关将来新增 stage 而报错。
+
+```
+        客户端请求
+             │
+   ┌─────────▼──────────┐
+   │  request_start     │  已解析、已鉴权，尚未选源
+   │  · type            │  "chat" | "stream" | "image"
+   │  · model           │  客户端请求的原始 model（"AUTO" 也在这里）
+   │  · key / role      │  掩码后的网关 key id（"***a1b2c3"）与角色
+   │  · source          │  空（还没选源）
+   │  · stream          │
+   │  · messages_count  │
+   │  · tools_count     │
+   │  · ts              │  unix 秒
+   └─────────┬──────────┘
+             │  （调度：tier 遍历 → 槽位轮转 → 冷却/配额过滤）
+   ┌─────────▼──────────┐
+   │  routed            │  已选定 (source, model)，尚未发往上游
+   │  · source / model  │  实际选中的
+   │  · tier            │  AUTO 链的档位；直连 = -1；AUTO = -2
+   │  · stream / key    │
+   └─────────┬──────────┘
+             │  （HTTP 往返 / SSE 流）
+   ┌─────────▼──────────┐
+   │  request_end       │  每个请求恰好一次，成功失败都触发
+   │  · ok / status     │
+   │  · latency_ms      │
+   │  · first_byte_ms   │  流式的首字节时间
+   │  · prompt_tokens   │  上游真实 usage，缺失时为字节估算
+   │  · completion_tokens
+   │  · cache_hit_tokens / cache_miss_tokens
+   │  · image_count     │  生图数量（图片不计 token）
+   │  · error           │  失败原因，成功时为 ""
+   │  · time            │  unix **毫秒**
+   └─────────┬──────────┘
+             │
+        写审计 + 聚合统计
+```
+
+### 3.1 触发点在哪
+
+| stage | 代码位置 | 说明 |
+|---|---|---|
+| `request_start` | `gateway/chat.go` `handleChat` / `fireImageStart` | 每个请求一次（chat 与生图各一条），在配额闸门**之前** |
+| `chain_step` | `gateway/chat.go` `chainTraceSink` | **仅 AUTO 路径**，每步一次 |
+| `routed` | `singleChat` / `streamChat` / `singleChatAuto` / `streamChatAuto` | 成功选定源之后，各一次 |
+| `request_end` | `gateway/chat.go` `writeRec` | **所有出口的唯一汇合点**，每个请求一次 |
+
+### 3.1b 为什么单独有 `chain_step`
+
+`routed` 只在**遍历结束后**触发一次，只带最终胜出的槽位。所以
+"tier 1 冷却所以降级到 tier 3"和"tier 1 正常接单"在它眼里**完全一样**——
+而这恰恰是优先级链存在的全部理由。
+
+`chain_step` 补上这条信息，四种 `kind`：
+
+| kind | 含义 | 何时产生 |
+|---|---|---|
+| `tier_skip` | 整档被跳过 | 该档所有槽位冷却中/配额用尽 |
+| `slot_fail` | 某个槽位硬失败 | 上游报错 / 适配器输出不可用 |
+| `tier_busy` | 整档全忙且有界等待超时 | 2s 内没等到空位 |
+| `selected` | 这个槽位接了单 | 每次成功遍历**恰好一次**，且是最后一步 |
+
+顺序保证：所有 `chain_step` 都在 `routed` 之前，`selected` 是最后一步。
+所以只订阅 `request_end` 的插件也能拿到轨迹摘要（见下）。
+
+### 3.1c `request_end` 里的轨迹摘要
+
+除了逐个 `chain_step`，`request_end` 还带三个便于做报表的字段：
+
+| 字段 | 含义 |
+|---|---|
+| `chain_walk` | 整个遍历的步骤数组（上限 12 步，超出截断） |
+| `degraded` | 布尔。`true` = 有过跳过/失败，即**发生了降级** |
+| `tier_served` | 实际服务的那一档；直连或全失败时为 `-1` |
+
+> **计费口径**：按**实际服务的模型**计费。降级到 tier 3 仍按 tier 3 的价算，
+> `chain_step` / `degraded` / `tier_served` 只作**观测**，不参与计价。
+> 理由见 §7.5。
+
+`request_end` 放在 `writeRec` 是因为四条入口路径（直连/AUTO × 流式/非流式）都
+经过它，既不会漏（流式的 token 数只有流结束才知道），也不会重复。
+
+**hot path 注意事项**：没有插件注册某 stage 时，`Fire` 立刻返回（一次 `RLock`
+加一次 map 查找）。装了插件之后，每个请求会在该 stage 上多一次 Lua 调用——
+这是同步的，在关键路径上。计费插件那种"每请求一次"是正常的；把重活放进钩子是
+反模式。
+
+### 3.2 钩子的返回值
+
+- 返回 `nil` 或不返回 = **没有意见**，payload 原样传给下一个插件
+- 返回 table = 其中的键会**合并进 payload**，并作为 `Fire` 的返回值
+
+**同一 stage 的多个插件并行执行**，但返回值按**插件加载顺序**合并，所以结果是
+确定的（不依赖 goroutine 调度）。代价是一个插件看不到另一个插件刚加的字段：
+每个钩子拿到的是**同一份 payload 快照**。
+
+这与早期版本不同 —— 早期是顺序执行，后一个插件能看到前一个的返回值。它从未被
+实际依赖（随核心发布的 billing 在每个 stage 都 `return nil`，注释里写着
+"nobody downstream would read a return value"），但这是一处**契约变化**：如果你的
+插件依赖「读到前一个插件写的字段」，并行的两个插件之间必须改用外部通信
+（例如各自写 `plugin.state`，由 `/api/plugins/<name>/state` 读取）。
+
+单个插件时不启 goroutine，直接调用。
+
+前三个 stage 的返回值目前没有内部消费者（最后一个 stage 之后就是写审计），
+所以计费插件改用 `plugin.state` + `/state` 端点来暴露数据。
+
+---
+
+## 4. 界面扩展
+
+### 4.1 整页
+
+```lua
+plugin.ui = {
+  page = {
+    page_id = "billing",   -- 必填,kebab-case。侧栏 data-tab 与 #tab-billing
+    title = "Billing",     -- 必填,侧栏文字
+    icon = "💰",           -- 可选
+    order = 40,            -- 侧栏排序,默认 100
+    mount = [[...HTML...]],
+  },
+}
+```
+
+### 4.2 往现有页面追加元素
+
+```lua
+plugin.ui = {
+  elements = {
+    {
+      target = "status",   -- status | chat | keys | sort | sources | adapters
+      anchor = "top",      -- "top" | "bottom" | "before:<sel>" | "after:<sel>"
+      order = 5,
+      mount = [[...HTML...]],
+    },
+  },
+}
+```
+
+### 4.3 `mount` 里可以带 `<script>` 和 `<style>`
+
+内核的注入顺序是：**先插 HTML，再执行 `<script>`**，所以脚本里访问
+`document.getElementById` 一定能拿到已渲染的节点。
+
+### 4.4 插件可用的浏览器端 API
+
+| API | 作用 |
+|---|---|
+| `window.pluginAPI.fetchState(name)` | 等价于 `GET /api/plugins/<name>/state` |
+| `window.pluginAPI.onTabShown(fn)` | 注册"页面切到可见时"的回调（轮询类组件用） |
+| `window.pluginAPI.postState(name, obj)` | `PUT` 自己的 state（写操作，需 admin） |
+
+### 4.5 一个完整例子
+
+见 `internal/lua/plugins/billing.lua`——它同时用了两种 UI 形式、完整的价格配置、
+以及全部三个 stage。
+
+---
+
+## 5. 插件状态与 HTTP API
+
+### 5.1 端点
+
+```
+GET    /api/plugins                  已加载插件清单 + 钩子 + UI + 错误
+POST   /api/plugins                  上传/替换（admin）{name, code}
+DELETE /api/plugins/{name}           删除（admin）
+GET    /api/plugins/{name}/state     读取插件自己发布的状态
+PUT    /api/plugins/{name}/state     替换状态（admin）
+```
+
+`GET .../state` 对**任意角色开放**：它是报表数据（开销、计数），用户自己的
+计费组件要能渲染。而 `PUT` 需要 admin。
+
+### 5.2 约定：`prices` 与 `state` 分离
+
+`PUT .../state` 的载荷里如果有 `prices` 键，它会被写进插件的 **`plugin.prices`**
+字段并从 `state` 里剔除。
+
+**为什么**：`state` 是累计量（历史），`prices` 是配置。一次改价如果整体替换
+`state`，累计量就没了——账目会在改价那一刻清零。分离之后：
+
+- 只带 `prices` → 改配置，**不动** `state`（累计量保留）
+- 带其它键 → 替换 `state`（这是显式的重置）
+
+> 插件可以不遵守这个约定，把整个载荷放进 `state` 自行处理。约定只为内置的
+> 计费插件存在。
+
+### 5.3 `GET /api/plugins` 的响应
+
+```json
+{
+  "plugins": [{
+    "name": "billing", "version": "1.0.0",
+    "description": "...", "author": "...",
+    "hooks": ["request_end"],
+    "ui": { "page": "billing", "elements": 1 },
+    "loaded": true
+  }],
+  "hook_errors": { "request_end": { "count": 3, "last_error": "billing: ..." } },
+  "plugin_dir": "/etc/llmsproxy/plugins"
+}
+```
+
+`hook_errors` 是**排错入口**：一个坏掉的插件表现为"功能缺失"而不是报错，
+这个计数让它可见。
+
+---
+
+## 6. 运行时约束（重要）
+
+### 6.1 一个插件 = 一个 Lua 状态
+
+适配器可以有多个独立的 worker 状态（它们无状态，这是对的）。**插件不行**：
+钩子通常往 `plugin.state` 里累加，多个状态就意味着总额被劈成几份，而写价格只
+写进其中一个状态，钩子恰好跑到另一个时**所有请求按 0 计费**。
+
+因此插件持有**唯一一个**状态，所有入口（`Fire` / `State` / `SetState`）用互斥锁
+串行化。代价：**一个卡住的钩子会卡住所有插件的钩子**。所以——
+
+> **钩子必须短、同步、不阻塞。** 不要在里面做 HTTP 请求、睡眠或重计算。
+
+### 6.2 异常被隔离
+
+钩子里 `error()` 不会影响转发：异常被捕获、记进 `hook_errors`、跳到下一个插件。
+适配器变换出错会让源进入冷却，但插件出错**不产生任何惩罚**——插件是可选功能。
+
+### 6.3 内置可用函数
+
+与适配器相同：`json.encode` / `json.decode`、`log(level, msg)`、
+`hmac_sha256_hex` / `sha256_hex` / `base64_encode` / `tohex`。
+
+⚠️ `os.date` 在极简运行时里可能不可用（计费插件因此有降级路径）。
+
+### 6.4 命名
+
+- 全局 `__llmsproxy_plugin` 存放插件返回的 table，**不要占用**
+- 插件间状态完全隔离，一个插件改不了另一个的全局
+
+---
+
+## 7. 内置计费插件
+
+`plugins/billing.lua`，默认随首启 seed 进来，开箱可用。
+
+### 7.1 计费维度
+
+| 维度 | 用途 | 优先级 |
+|---|---|---|
+| `sources` | 源的固定价（如按请求计费的转发服务） | 中 |
+| `models` | 模型的 per-token 价 | 高 |
+| `keys` | 单个网关 key 的覆盖价 | **最高** |
+
+**token 价**优先级：`keys` > `models` > `default`。
+**`per_request` 固定价是叠加的**（不覆盖），所以一个生图模型可以既算 token 又收固定费。
+**`cache_discount`** 见 §7.7。
+
+### 7.2 价格单位
+
+**USD / 单个 token**。这是各家 provider 的公布口径，所以典型数值长这样：
+`1.25e-6`。插件内部乘以 token 数，全程不做单位换算。
+
+```json
+{
+  "prices": {
+    "currency": "USD",
+    "default":  { "prompt": 0, "completion": 0, "per_request": 0 },
+    "sources":  { "trae": { "per_request": 0.01 } },
+    "models":   {
+      "gpt-5.4": { "prompt": 1.25e-6, "completion": 1e-5 },
+      "kolors":  { "per_request": 0.04 }
+    },
+    "keys":     { "***a1b2c3": { "prompt": 1.1e-6, "completion": 9e-6 } }
+  }
+}
+```
+
+配置价目：
+
+```bash
+curl -X PUT http://127.0.0.1:8080/api/plugins/billing/state \
+  -H "Authorization: Bearer $ADMIN_KEY" -H "Content-Type: application/json" \
+  -d '{"prices":{"models":{"gpt-5.4":{"prompt":1.25e-6,"completion":1e-5}}}}'
+```
+
+读回账目：
+
+```bash
+curl -H "Authorization: Bearer $ADMIN_KEY" \
+  http://127.0.0.1:8080/api/plugins/billing/state
+```
+
+### 7.3 累计维度
+
+`total` / `by_source` / `by_model` / `by_key` / `by_day`（`YYYY-MM-DD` UTC），
+每项含 `cost`、`requests`、`prompt_tokens`、`completion_tokens`、`failures`。
+
+另有两个**降级观测**维度（来自 `chain_step`）：
+
+| 字段 | 含义 |
+|---|---|
+| `degraded_reqs` | 发生过降级的请求数 |
+| `by_tier_served` | 各档实际接单数（`{"1": 812, "2": 37}`） |
+| `skip_reasons` | 跳过原因计数，等待时长已归一（`no free slot within <wait>`） |
+
+这三项是"网关是不是在悄悄降级"的核心指标：一个持续降级的网关，账单结构和健康
+网关看起来一模一样——**除非**单独统计降级次数。
+
+### 7.4 计费策略：失败的请求怎么算
+
+**保留 token 费用，丢弃固定费用。** 理由：上游在生成后才 500，token 确实被消耗
+了；但那个从未真正发生的固定费不该收。
+
+这是本插件里**最可争议的一条**。想改成"失败也收固定费"：
+
+```json
+{ "prices": { ... }, "count_failures": true }
+```
+
+### 7.5 ⚠️ 计费插件只报表，不执法
+
+**网关自己的配额会计（`internal/gateway/stats.go`，入口处强制）才是限额权威。**
+本插件不参与任何路由或配额决策。
+
+理由：两套独立的会计路径如果对不上，比一套功能略少的更糟。计费是**观察**，
+配额是**控制**，二者分开。
+
+### 7.6 未定价流量（重要）
+
+**任何维度都没配价的请求，成本记 0。** 这是最危险的失败模式：账单照样能加总，
+只是**悄悄少报**，而且没有任何报错。
+
+所以插件单独统计它们：
+
+| 字段 | 含义 |
+|---|---|
+| `unpriced_reqs` | 没有任何价目覆盖的请求数 |
+| `unpriced_models` | 按模型点名（`{"MYSTERY-MODEL": 12}`）——直接告诉你价目表缺了哪一行 |
+
+仪表盘上有 "Unpriced" 卡片。**这个数应该是 0**；不是 0 就去补价目。
+
+注意"未定价"不等于"免费"：这些请求的 `requests` / token 数**照常计入**
+`total` 与各维度，只有金额是 0。
+
+### 7.7 提示缓存计价
+
+**缓存命中的 prompt token 不按全价算。** 绝大多数 provider 对缓存读给很深的折扣
+（常见是 1/10），而 agent 流量会反复重放长前缀——正是缓存要让它便宜的那类流量。
+
+```
+fresh  = prompt_tokens - cache_hit_tokens   → 全价
+cached = cache_hit_tokens                   → 全价 × cache_discount
+```
+
+`cache_discount` 默认 **0.1**（10 倍折扣），因为 DeepSeek / Qwen / Kimi 等都是这个
+量级。它是**每个 provider 的事实、不是自然常数**，所以可以按条目覆盖：
+
+```json
+"models": { "gpt-5.4": { "prompt": 1.25e-6, "completion": 1e-5, "cache_discount": 0.25 } }
+```
+
+设成 `1` 恢复成旧的"prompt 一律全价"行为，设成 `0` 表示该 provider 不打折。
+
+优先级与 token 价一致（`keys` > `models` > `default`）。
+
+> **这一条改过行为。** 修复前缓存命中按全价算：100 万 prompt token 里 90 万是
+> 缓存命中，会算出 10 USD 而不是 ~1.9——**高估约 10 倍**，而且恰好发生在缓存
+> 最有价值的高频流量上。
+
+### 7.8 数据从哪来
+
+`request_end` 的 `prompt_tokens` / `completion_tokens` 优先取上游真实的
+`usage`；上游没报时网关用字节估算（`len/3+1`）。流式请求在流结束后用上游真实
+数字**覆盖**估算值。所以计费数字的精度取决于上游是否报 usage。
+
+---
+
+## 8. 排错
+
+| 现象 | 查什么 |
+|---|---|
+| 插件没出现在 `/api/plugins` | 目录对不对（响应里的 `plugin_dir`）；文件是不是 `.lua` |
+| `loaded: false` 且有 `error` | 语法错误或没 `return table`，错误信息在 `error` 字段 |
+| 功能"没反应"但无报错 | 查 `hook_errors`——坏钩子只记录不抛出 |
+| 钩子没被调用 | 该 stage 确实触发了吗（`routed` 只在**成功**选源后触发，调度全失败时不触发） |
+| 界面空白 | 内核的 `GET /api/ui-inject` 里有没有你的 `page_id`；脚本有没有报错（浏览器 console） |
+| `pluginAPI` 未定义 | 脚本在注入前执行了；确认用的是 `mount` 而不是别的方式插入 |
+
+### 调试钩子
+
+插件的 `log(level, msg)` 输出到网关的日志：
+
+```
+journalctl -u llmsproxy -f | grep -i plugin
+```
+
+---
+
+## 9. 与适配器的区别
+
+| | 适配器 | 插件 |
+|---|---|---|
+| 位置 | `adapter_dir` | `plugin_dir` |
+| 作用 | 上游协议转换 | 请求流水线 + 界面 |
+| 钩子 | `transform_request` / `transform_response` / `transform_stream_chunk` / `build_headers` / `transform_error` | `request_start` / `routed` / `request_end` |
+| 状态 | 每个源独立，多 worker | 单状态，见 §6.1 |
+| 出错后果 | 该 (源,模型) 进入冷却退避 | 仅该功能缺失 |
+| 鉴权 | 需要 `gateway_keys` 之外的独立凭据 | 网关 key |
+| 必需性 | 核心 | 可选，缺了网关照常跑 |
+
+完整适配器协议见 [lua-adapters.md](lua-adapters.md)。

internal/billing/compile.go

@@ -0,0 +1,264 @@
+package billing
+
+import (
+	"fmt"
+	"strings"
+
+	"llmsproxy/internal/config"
+)
+
+// Compile turns one billing profile into the prices table the billing plugin
+// expects, resolving URL rules against the gateway's actual sources.
+//
+// WHY URL RULES NEED RESOLVING AT ALL: the operator declares pricing by URL
+// because that is what a provider's price list is keyed on, and because several
+// sources can point at the same URL. The plugin, however, looks up by
+// `payload.source` (a source NAME) and by model — it has no idea what URL a
+// request went to. So the URL match happens here, at compile time, where the
+// config's name->base_url mapping is known, and the result is expressed in the
+// dimensions the plugin already supports.
+//
+// Profiles are the "let the user choose" axis: the same URL can appear in
+// several profiles and switching recomputes this table, so a gateway can be
+// repriced without editing the plugin.
+func Compile(profile *config.BillingProfile, sources []config.Source) (map[string]interface{}, error) {
+	return CompileOpts(profile, sources, false)
+}
+
+// CompileOpts is Compile with an explicit policy for rules that match no
+// source.
+//
+// The default is STRICT and that is correct for startup: a profile with a
+// typo'd URL prices nothing, every request on it is recorded as unpriced, and
+// the bill silently comes out wrong. Failing the load is the right response.
+//
+// The rules editor needs the opposite. An operator editing a half-finished
+// profile — adding a rule before the source that will use it exists, or
+// renaming a URL while typing — must be able to save and then see the warning,
+// not be blocked by an error they can only resolve by guessing. Lenient mode
+// keeps the offending rule in the config and drops it from the compiled table,
+// so it is preserved as text and clearly reported, without pretending it
+// prices anything.
+func CompileOpts(profile *config.BillingProfile, sources []config.Source, lenient bool) (map[string]interface{}, error) {
+	if profile == nil {
+		return nil, fmt.Errorf("no billing profile")
+	}
+	prices := map[string]interface{}{
+		"currency": "USD",
+		"default":  map[string]interface{}{"prompt": 0.0, "completion": 0.0, "per_request": 0.0},
+		"sources":  map[string]interface{}{},
+		"models":   map[string]interface{}{},
+		"keys":     map[string]interface{}{},
+	}
+	if profile.Default != "" {
+		prices["default_mode"] = profile.Default
+	}
+
+	// Currency is a profile-level statement; a rule may override it.
+	for i := range profile.Rules {
+		if c := profile.Rules[i].Currency; c != "" {
+			prices["currency"] = c
+			break
+		}
+	}
+
+	matched := map[string]bool{}
+	for i := range profile.Rules {
+		rule := &profile.Rules[i]
+		targets := matchSources(rule.URL, sources)
+		if len(targets) == 0 && rule.URL != "*" {
+			// A rule for a URL no source uses is almost always a typo (or a
+			// source that was removed). Failing loudly beats a profile that
+			// silently prices nothing — the whole reason this is a config file
+			// instead of a hand-written JSON blob.
+			if lenient {
+				continue // kept in the config text, reported as a warning
+			}
+			return nil, fmt.Errorf("rule url %q matches no configured source base_url", rule.URL)
+		}
+		for _, srcName := range targets {
+			if matched[srcName] {
+				// First rule wins. Two rules matching one source is ambiguous,
+				// and silently letting the later one win makes the file's
+				// meaning depend on ordering the operator cannot see.
+				continue
+			}
+			matched[srcName] = true
+			if err := applyRule(prices, rule, srcName, sources); err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	// Sources no rule matched fall through to the profile default, which the
+	// plugin applies via prices.default. Recording them explicitly means the
+	// UI can say "this source is unpriced" instead of leaving the operator to
+	// infer it from a zero.
+	var unmatched []string
+	for _, src := range sources {
+		if !matched[src.Name] {
+			unmatched = append(unmatched, src.Name)
+		}
+	}
+	if len(unmatched) > 0 {
+		prices["unmatched_sources"] = unmatched
+	}
+	return prices, nil
+}
+
+// matchSources returns the source names whose base_url matches pattern.
+// "*" matches every source (used as a catch-all default rule).
+func matchSources(pattern string, sources []config.Source) []string {
+	var out []string
+	if pattern == "*" {
+		for _, s := range sources {
+			out = append(out, s.Name)
+		}
+		return out
+	}
+	want := normalizeURL(pattern)
+	for _, s := range sources {
+		if normalizeURL(s.BaseURL) == want {
+			out = append(out, s.Name)
+		}
+	}
+	return out
+}
+
+// normalizeURL compares URLs the way an operator expects: trailing slashes and
+// case in the host are differences the provider's price list does not care
+// about, and requiring an exact byte match would make the config brittle.
+func normalizeURL(u string) string {
+	u = strings.TrimSpace(u)
+	u = strings.TrimRight(u, "/")
+	return strings.ToLower(u)
+}
+
+// applyRule writes one rule's pricing for one source into the prices table.
+func applyRule(prices map[string]interface{}, rule *config.BillingRule, srcName string, sources []config.Source) error {
+	switch rule.Mode {
+	case "free":
+		// Explicitly priced at zero. This is NOT the same as unpriced: a source
+		// the operator says is free must not appear in the unpriced warnings,
+		// or those warnings become noise and stop being read.
+		prices["sources"].(map[string]interface{})[srcName] = map[string]interface{}{
+			"prompt": 0.0, "completion": 0.0, "per_request": 0.0,
+		}
+		return nil
+
+	case "subscription":
+		// A fixed monthly commitment: the per-request MARGINAL cost is zero, and
+		// the flat fee is reported separately. Spreading a monthly fee across
+		// requests would invent a per-request number the provider never charges,
+		// and it would change every time traffic did.
+		prices["sources"].(map[string]interface{})[srcName] = map[string]interface{}{
+			"prompt": 0.0, "completion": 0.0, "per_request": 0.0,
+		}
+		fixed, _ := prices["subscriptions"].(map[string]interface{})
+		if fixed == nil {
+			fixed = map[string]interface{}{}
+			prices["subscriptions"] = fixed
+		}
+		cur := "USD"
+		if rule.Currency != "" {
+			cur = rule.Currency
+		}
+		fixed[srcName] = map[string]interface{}{
+			"monthly": rule.Subscription, "currency": cur,
+		}
+		return nil
+
+	case "unpriced":
+		// Deliberately left out of `sources` so the plugin's unpriced_models /
+		// unpriced_reqs counters catch it. That is the point: a subscription
+		// plan whose credits cannot be converted to tokens must be VISIBLE as
+		// unbilled, not quietly estimated.
+		return nil
+
+	case "token":
+		if len(rule.Models) == 0 {
+			return fmt.Errorf("rule for url %q: mode token requires at least one model", rule.URL)
+		}
+		models := prices["models"].(map[string]interface{})
+		for modelID, t := range rule.Models {
+			entry := map[string]interface{}{}
+			prompt, err := usdPerM(t.Prompt)
+			if err != nil {
+				return fmt.Errorf("model %q prompt: %w", modelID, err)
+			}
+			completion, err := usdPerM(t.Completion)
+			if err != nil {
+				return fmt.Errorf("model %q completion: %w", modelID, err)
+			}
+			entry["prompt"] = prompt
+			entry["completion"] = completion
+			if t.CacheDiscount != nil {
+				entry["cache_discount"] = *t.CacheDiscount
+			}
+			if rule.Peak != nil {
+				entry["peak"] = compilePeak(rule.Peak)
+			}
+			models[modelID] = entry
+		}
+		// A specific-URL token rule needs a source entry so a model served
+		// from THIS url but absent from `rule.Models` is still recognised as
+		// belonging to a priced provider.
+		//
+		// A WILDCARD rule ("*") must NOT get one. "*" is a model catalogue — it
+		// says "these model ids have these prices, wherever they come from" —
+		// and marking every source priced at {0,0} would make priceFor() set
+		// priced=true for every model the catalogue does NOT list. Paid
+		// sources (commandcode, alittokenplan, …) would then record $0 instead
+		// of showing up in unpriced_reqs, which is precisely the silent
+		// zero-billing failure this whole plugin is built to make visible.
+		// The model lookup p.models[payload.model] already marks a listed
+		// model priced on its own, so the wildcard loses nothing.
+		if rule.URL != "*" {
+			if _, ok := prices["sources"].(map[string]interface{})[srcName]; !ok {
+				prices["sources"].(map[string]interface{})[srcName] = map[string]interface{}{
+					"prompt": 0.0, "completion": 0.0, "per_request": 0.0,
+				}
+			}
+		}
+		return nil
+	}
+	return fmt.Errorf("unknown mode %q", rule.Mode)
+}
+
+// usdPerM converts a USD-per-million string into the per-token rate the plugin
+// expects. Delegates to config.ParseFloatUSDPerM so the DSL validator and the
+// compiler agree byte-for-byte on what a valid price is — a value that passes
+// Validate() but fails here (or vice versa) would be the worst kind of drift.
+func usdPerM(s string) (float64, error) {
+	return config.ParseFloatUSDPerM(s)
+}
+
+// compilePeak renders the peak window in the shape the plugin reads:
+// { multiplier, windows = { { days = {...}, hours = { {lo,hi}, ... } } } }.
+//
+// The plugin reads `days` / `hours` pairs. The first version of the deployed
+// price table used { start, end, weekdays } — a shape nothing reads — so peak
+// traffic was billed at off-peak rates with no error anywhere. Compiling from
+// typed config fields removes the chance of writing the wrong key names by hand.
+func compilePeak(p *config.BillingPeak) map[string]interface{} {
+	win := map[string]interface{}{}
+	if len(p.Weekdays) > 0 {
+		days := make([]interface{}, 0, len(p.Weekdays))
+		for _, d := range p.Weekdays {
+			days = append(days, d)
+		}
+		win["days"] = days
+	}
+	if len(p.Hours) > 0 {
+		hours := make([]interface{}, 0, len(p.Hours))
+		for _, h := range p.Hours {
+			hours = append(hours, []interface{}{h[0], h[1]})
+		}
+		win["hours"] = hours
+	}
+	out := map[string]interface{}{"multiplier": p.Multiplier}
+	if len(win) > 0 {
+		out["windows"] = []interface{}{win}
+	}
+	return out
+}

internal/billing/wildcard_test.go

@@ -0,0 +1,88 @@
+package billing
+
+import (
+	"testing"
+
+	"llmsproxy/internal/config"
+)
+
+// The wildcard token rule must not blanket-mark every source as priced.
+//
+// Why this is a hazard and not a style question: priceFor() sets priced=true as
+// soon as the request's SOURCE has an entry in the price table, and that flag
+// is what keeps a request OUT of unpriced_reqs. A "*" rule is a model
+// catalogue — it prices specific model ids wherever they come from — but
+// compiling it into a {0,0,0} entry on all 21 sources made every model the
+// catalogue does not list look "priced at zero". Paid providers (commandcode,
+// alittokenplan, …) then stopped appearing in the unpriced warnings, which is
+// exactly the silent zero-billing failure the plugin exists to surface.
+func TestWildcardTokenRuleDoesNotMarkEverySourcePriced(t *testing.T) {
+	sources := []config.Source{
+		{Name: "free1", BaseURL: "https://free1.example.com/v1"},
+		{Name: "paid1", BaseURL: "https://paid1.example.com/v1"},
+		{Name: "paid2", BaseURL: "https://paid2.example.com/v1"},
+	}
+	profile := &config.BillingProfile{
+		ID: "p",
+		Rules: []config.BillingRule{
+			{URL: "https://free1.example.com/v1", Mode: "free"},
+			{
+				URL: "*", Mode: "token",
+				Models: map[string]config.BillingToken{
+					"only-catalogued-model": {Prompt: "1.00", Completion: "2.00"},
+				},
+			},
+		},
+	}
+	prices, err := Compile(profile, sources)
+	if err != nil {
+		t.Fatalf("compile: %v", err)
+	}
+	srcs := prices["sources"].(map[string]interface{})
+
+	// The explicitly free source keeps its entry (free is a deliberate 0).
+	if _, ok := srcs["free1"]; !ok {
+		t.Error("the explicit free rule lost its source entry")
+	}
+	// Paid sources must NOT be marked, or their unlisted models bill $0.
+	for _, name := range []string{"paid1", "paid2"} {
+		if _, ok := srcs[name]; ok {
+			t.Errorf("★ wildcard token rule marked %q as priced at 0 — its unlisted "+
+				"models will bill $0 instead of appearing as unpriced", name)
+		}
+	}
+	// The catalogue itself must still be present, or the rule prices nothing.
+	models := prices["models"].(map[string]interface{})
+	if _, ok := models["only-catalogued-model"]; !ok {
+		t.Error("the wildcard rule did not publish its model price")
+	}
+}
+
+// The inverse guard: a token rule for a SPECIFIC url still marks that source,
+// because it genuinely declares pricing for the models served from it.
+func TestSpecificURLTokenRuleStillMarksItsSource(t *testing.T) {
+	sources := []config.Source{
+		{Name: "mine", BaseURL: "https://mine.example.com/v1"},
+		{Name: "other", BaseURL: "https://other.example.com/v1"},
+	}
+	profile := &config.BillingProfile{
+		ID: "p",
+		Rules: []config.BillingRule{{
+			URL: "https://mine.example.com/v1", Mode: "token",
+			Models: map[string]config.BillingToken{
+				"m": {Prompt: "1.00", Completion: "2.00"},
+			},
+		}},
+	}
+	prices, err := Compile(profile, sources)
+	if err != nil {
+		t.Fatalf("compile: %v", err)
+	}
+	srcs := prices["sources"].(map[string]interface{})
+	if _, ok := srcs["mine"]; !ok {
+		t.Error("a specific-url token rule must still mark its own source priced")
+	}
+	if _, ok := srcs["other"]; ok {
+		t.Error("an unrelated source was marked priced by a specific-url rule")
+	}
+}

internal/config/config.go

@@ -7,6 +7,8 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strconv"
+	"strings"
 	"time"
 
 	"gopkg.in/yaml.v3"
@@ -19,6 +21,7 @@ type Config struct {
 	GatewayKeys   []string     `yaml:"gateway_keys"`
 	DefaultModel  string       `yaml:"default_model"` // e.g. "AUTO" or a model id
 	AdapterDir    string       `yaml:"adapter_dir"`
+	PluginDir     string       `yaml:"plugin_dir,omitempty"` // Lua plugin directory (optional; hooks + WebUI extensions)
 	RuntimeFile   string       `yaml:"runtime_file"`
 	TLSCertFile   string       `yaml:"tls_cert_file,omitempty"`   // PEM cert; when set together with tls_key_file, serve HTTPS
 	TLSKeyFile    string       `yaml:"tls_key_file,omitempty"`    // PEM private key
@@ -27,6 +30,15 @@ type Config struct {
 	Auto          []ModelScope `yaml:"auto,omitempty"`       // AUTO 调度链规则（WebUI 优先级页编辑，chat）
 	AutoImage     []ModelScope `yaml:"auto_image,omitempty"` // AUTO 生图调度链规则（WebUI 优先级页·生图）
 	Keys          []GWKey      `yaml:"keys,omitempty"`       // 网关密钥（WebUI 密钥页管理）
+	// BillingDSL declares per-URL pricing profiles for the billing plugin.
+	//
+	// Declarative, because hand-writing the prices JSON was error-prone in ways
+	// that looked successful: the first PUT went out without the required
+	// `prices` wrapper and silently REPLACED the accumulated totals with the
+	// price table; the second used a peak-window shape the plugin does not read,
+	// so peak traffic was billed at off-peak rates — no error, the bill just
+	// quietly halved. A schema-checked config file catches both at load.
+	BillingDSL *BillingDSL `yaml:"billing,omitempty"`
 	// box seals credentials (sources' api_key/headers, keys' key) at rest.
 	// In-memory values are always plaintext; only the bytes on disk are sealed.
 	// Wired by AttachSecretBox — Load leaves it nil so `-check` and tests stay
@@ -132,6 +144,7 @@ func writeDefaultConfig(path string) error {
 		GatewayKeys:  []string{key},
 		DefaultModel: "AUTO",
 		AdapterDir:   filepath.Join(abs, "adapters"),
+		PluginDir:    filepath.Join(abs, "plugins"),
 		RuntimeFile:  filepath.Join(abs, "runtime.json"),
 	}
 	out, err := yaml.Marshal(&cfg)
@@ -288,6 +301,9 @@ func (c *Config) ApplyDefaults() error {
 	if c.AdapterDir == "" {
 		c.AdapterDir = "adapters"
 	}
+	// PluginDir is deliberately NOT defaulted: with no plugins a missing
+	// directory would be created and seeded on every start for nothing. An
+	// operator opts in by setting it (or by dropping files into it).
 	if c.RuntimeFile == "" {
 		c.RuntimeFile = "runtime.json"
 	}
@@ -377,6 +393,144 @@ type GWKey struct {
 	Seed      bool         `yaml:"seed,omitempty" json:"seed,omitempty"` // true if migrated from config gateway_keys
 }
 
+// BillingDSL holds declarative per-URL pricing profiles for the billing plugin.
+//
+// Profiles are the "let the user pick" axis: the same upstream URL can be
+// declared under multiple profiles, and the operator chooses which is active.
+// Switching recomputes and re-injects the billing plugin's prices table.
+type BillingDSL struct {
+	// Active is the id of the profile in effect. Empty => the first profile.
+	Active   string           `yaml:"active,omitempty" json:"active,omitempty"`
+	Profiles []BillingProfile `yaml:"profiles,omitempty" json:"profiles,omitempty"`
+}
+
+// BillingProfile is one named set of per-URL pricing rules.
+type BillingProfile struct {
+	ID    string `yaml:"id" json:"id"`
+	Label string `yaml:"label,omitempty" json:"label,omitempty"`
+	// Default applies when no rule matches: "free" or "unpriced".
+	Default string        `yaml:"default,omitempty" json:"default,omitempty"`
+	Rules   []BillingRule `yaml:"rules,omitempty" json:"rules,omitempty"`
+}
+
+// BillingRule declares the pricing for everything under one URL.
+type BillingRule struct {
+	// URL matches a source's base_url. "*" = any unmatched URL.
+	URL string `yaml:"url" json:"url"`
+	// Mode is one of: free, token, subscription, unpriced.
+	Mode     string `yaml:"mode" json:"mode"`
+	Currency string `yaml:"currency,omitempty" json:"currency,omitempty"`
+	// Subscription is the flat monthly cost (for mode=subscription).
+	Subscription float64 `yaml:"subscription,omitempty" json:"subscription,omitempty"`
+	// Models declares per-token prices when mode=token.
+	Models map[string]BillingToken `yaml:"models,omitempty" json:"models,omitempty"`
+	// Free is true when mode=free (kept for explicitness).
+	// Peak applies to ALL token-priced requests under this URL.
+	Peak *BillingPeak `yaml:"peak,omitempty" json:"peak,omitempty"`
+}
+
+// BillingToken is the per-model price.
+type BillingToken struct {
+	Prompt        string   `yaml:"prompt" json:"prompt"`         // USD per million tokens, e.g. "0.15"
+	Completion    string   `yaml:"completion" json:"completion"` // USD per million tokens
+	CacheDiscount *float64 `yaml:"cache_discount,omitempty" json:"cache_discount,omitempty"`
+}
+
+// BillingPeak declares peak-hour pricing.
+type BillingPeak struct {
+	Multiplier float64 `yaml:"multiplier" json:"multiplier"`
+	// Weekdays: 1=Mon..5=Fri (Lua os.date !%w, 0=Sun)
+	Weekdays []int `yaml:"weekdays,omitempty" json:"weekdays,omitempty"`
+	// Hours: each pair is [lo,hi] inclusive
+	Hours [][2]int `yaml:"hours,omitempty" json:"hours,omitempty"`
+}
+
+// Validate rejects a BillingDSL that could not work as written.
+func (b *BillingDSL) Validate() error {
+	if b == nil {
+		return nil
+	}
+	ids := map[string]bool{}
+	for i := range b.Profiles {
+		p := &b.Profiles[i]
+		if p.ID == "" {
+			return fmt.Errorf("billing profile [%d] has no id", i)
+		}
+		if ids[p.ID] {
+			return fmt.Errorf("billing profile id %q appears more than once", p.ID)
+		}
+		ids[p.ID] = true
+		if p.Default != "" && p.Default != "free" && p.Default != "unpriced" {
+			return fmt.Errorf("profile %q: default must be free or unpriced, got %q", p.ID, p.Default)
+		}
+		for j := range p.Rules {
+			r := &p.Rules[j]
+			if r.URL == "" {
+				return fmt.Errorf("profile %q rule [%d]: url is required", p.ID, j)
+			}
+			switch r.Mode {
+			case "free", "token", "subscription", "unpriced":
+			default:
+				return fmt.Errorf("profile %q rule [%d]: mode must be free/token/subscription/unpriced, got %q", p.ID, j, r.Mode)
+			}
+			if r.Mode == "token" {
+				for m, t := range r.Models {
+					if t.Prompt == "" || t.Completion == "" {
+						return fmt.Errorf("profile %q model %q: prompt and completion are required for token mode", p.ID, m)
+					}
+					if _, err := ParseFloatUSDPerM(t.Prompt); err != nil {
+						return fmt.Errorf("profile %q model %q prompt: %w", p.ID, m, err)
+					}
+					if _, err := ParseFloatUSDPerM(t.Completion); err != nil {
+						return fmt.Errorf("profile %q model %q completion: %w", p.ID, m, err)
+					}
+				}
+			}
+		}
+	}
+	// Active must resolve to a profile id.
+	if b.Active != "" && !ids[b.Active] {
+		return fmt.Errorf("billing.active = %q but no profile has that id", b.Active)
+	}
+	return nil
+}
+
+// Resolve returns the profile with the given id; empty id (or an id that does
+// not exist) falls back to the FIRST profile. A config with profiles but no
+// active marker should mean "use the one I wrote first" rather than "price
+// nothing", which is what a nil here would silently do.
+func (b *BillingDSL) Resolve(id string) *BillingProfile {
+	if b == nil || len(b.Profiles) == 0 {
+		return nil
+	}
+	if id != "" {
+		for i := range b.Profiles {
+			if b.Profiles[i].ID == id {
+				return &b.Profiles[i]
+			}
+		}
+	}
+	return &b.Profiles[0]
+}
+
+// parseFloatUSDPerM parses a USD-per-million price string. Returns the
+// per-single-token rate the plugin expects (price / 1e6).
+//
+// Kept as a string in the DSL rather than a float: "0.15" survives round-trips
+// through YAML editors, and a malformed value must fail VALIDATION (with the
+// file and field named) rather than parse as 0 and under-bill silently — which
+// is exactly the failure mode that motivated the DSL.
+func ParseFloatUSDPerM(s string) (float64, error) {
+	f, err := strconv.ParseFloat(strings.TrimSpace(s), 64)
+	if err != nil {
+		return 0, fmt.Errorf("not a number: %q", s)
+	}
+	if f < 0 {
+		return 0, fmt.Errorf("negative price: %q", s)
+	}
+	return f / 1e6, nil
+}
+
 // KeyQuota is retained only to carry a scope entry's caps through the admin
 // API. Quotas are per model, never per key: there is deliberately no key-wide
 // total, so exhausting one model's budget never blocks the others.

internal/core/core.go

@@ -16,6 +16,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"llmsproxy/internal/billing"
 	"llmsproxy/internal/config"
 	"llmsproxy/internal/lua"
 	"llmsproxy/internal/provider"
@@ -30,6 +31,7 @@ type Core struct {
 	mu             sync.Mutex
 	cfg            *config.Config
 	vm             *lua.VM
+	plugins        *lua.Plugins
 	store          *config.Store
 	scheduler      *scheduler.Scheduler
 	registry       *provider.Registry
@@ -53,6 +55,28 @@ func NewFromConfig(cfg *config.Config) (*Core, error) {
 	if err := c.vm.Start(); err != nil {
 		return nil, fmt.Errorf("lua vm: %w", err)
 	}
+	// Plugins load AFTER the VM is up (a plugin is just another Lua state) but
+	// BEFORE anything can serve traffic, so a plugin's request_end hook sees
+	// the very first request. A plugin that fails to load is logged and skipped
+	// rather than failing startup: plugins are optional extensions, and failing
+	// to boot the gateway because a third-party .lua has a typo would be the
+	// wrong trade.
+	c.plugins = lua.NewPlugins(c.vm, cfg.PluginDir)
+	if err := c.plugins.SeedBundled(); err != nil {
+		log.Printf("[core] seed bundled plugins: %v", err)
+	}
+	if err := c.plugins.LoadDir(); err != nil {
+		log.Printf("[core] plugin dir: %v", err)
+	}
+	for _, p := range c.plugins.List() {
+		if msg, bad := p["error"]; bad {
+			log.Printf("[core] plugin %v failed to load: %v", p["name"], msg)
+			continue
+		}
+		log.Printf("[core] plugin %v %v loaded (hooks=%v ui=%v)",
+			p["name"], p["version"], p["hooks"], p["ui"])
+	}
+	c.applyBillingDSL()
 	c.store = config.NewStore(cfg.RuntimeFile)
 	// Share one box between the runtime store and config.yaml so a single
 	// master.key seals both files. config.Load left the config holding
@@ -221,6 +245,11 @@ func buildRetries(cfg *config.Config) int {
 // VM exposes the Lua adapter runtime.
 func (c *Core) VM() *lua.VM { return c.vm }
 
+// Plugins exposes the loaded plugin set. Never nil once New* has returned, so
+// the gateway can fire stages unconditionally; an unconfigured plugin
+// directory yields an empty registry whose Fire is a no-op.
+func (c *Core) Plugins() *lua.Plugins { return c.plugins }
+
 func (c *Core) Scheduler() *scheduler.Scheduler { return c.scheduler }
 
 func (c *Core) Registry() *provider.Registry { return c.registry }
@@ -799,11 +828,75 @@ func normalizeSource(s *config.Source) error {
 
 // Close releases resources.
 func (c *Core) Close() {
+	// Plugin state must be flushed BEFORE the VM stops. The saver's final write
+	// reads each plugin's Lua tables; once vm.Stop() has closed those states the
+	// read finds nothing and the last interval of accumulation is lost — which
+	// is the exact failure this persistence was added to prevent.
+	if c.plugins != nil {
+		c.plugins.Close()
+	}
 	if c.vm != nil {
 		c.vm.Stop()
 	}
 }
 
+// applyBillingDSL compiles the configured billing profile and injects it into
+// the billing plugin.
+//
+// Configured pricing replaces the hand-written JSON blob that used to be PUT
+// through the state API. That path was used twice in production and both times
+// it "succeeded" while being wrong: once without the required `prices` wrapper
+// (silently wiping the accumulated totals), once with a peak-window shape the
+// plugin does not read (peak traffic billed at off-peak rates, no error). A
+// typed config with load-time validation turns both mistakes into startup
+// errors naming the file and field.
+//
+// A DSL with no profile, or one that fails to compile, leaves the plugin's
+// prices untouched: billing keeps running on whatever it had, and the problem
+// is logged rather than becoming a startup failure — the gateway must forward
+// even when its cost accounting is misconfigured.
+func (c *Core) applyBillingDSL() {
+	ps := c.plugins
+	if ps == nil || ps.Count() == 0 {
+		return
+	}
+	// The billing plugin may simply not be installed; a DSL without it is a
+	// no-op, not an error.
+	var have bool
+	for _, row := range ps.List() {
+		if row["name"] == "billing" && row["loaded"] == true {
+			have = true
+			break
+		}
+	}
+	if !have {
+		return
+	}
+	dsl := c.cfg.BillingDSL
+	if dsl == nil || len(dsl.Profiles) == 0 {
+		return
+	}
+	if err := dsl.Validate(); err != nil {
+		log.Printf("[billing] config invalid, profile not applied: %v", err)
+		return
+	}
+	profile := dsl.Resolve(dsl.Active)
+	if profile == nil {
+		log.Printf("[billing] no billing profile resolved (active=%q)", dsl.Active)
+		return
+	}
+	prices, err := billing.Compile(profile, c.cfg.Sources)
+	if err != nil {
+		log.Printf("[billing] profile %q not applied: %v", profile.ID, err)
+		return
+	}
+	if err := ps.SetState("billing", map[string]interface{}{"prices": prices}); err != nil {
+		log.Printf("[billing] applying profile %q: %v", profile.ID, err)
+		return
+	}
+	log.Printf("[billing] profile %q applied (%d rules, %d sources)", profile.ID, len(profile.Rules), len(c.cfg.Sources))
+}
+
 // ValidateScopeQuotas checks every scope entry's caps before they are stored.
 // A typo in a period must be rejected at write time rather than silently
 // becoming a never-resetting budget — the opposite of what was typed.

internal/gateway/api.go

@@ -3,6 +3,7 @@ package gateway
 import (
 	"encoding/csv"
 	"encoding/json"
+	"fmt"
 	"io"
 	"log"
 	"net/http"
@@ -83,6 +84,121 @@ type sourcePayload struct {
 	// It exists because "add one model" is the most common scripted edit and a
 	// full Models list cannot be written without reading the source first.
 	ModelIDs []string `json:"model_ids,omitempty"`
+
+	// The four fields below are POINTERS, and that is the whole point.
+	//
+	// POST/PUT is an upsert that rewrites the whole source, so any field the
+	// payload cannot express is silently reset to its zero value. That already
+	// destroyed api_key once (fixed with resolveAPIKey) and would equally
+	// destroy proxy_url, api_key_env, timeout and queue_timeout.
+	//
+	// A plain string/duration cannot distinguish "the caller did not mention
+	// this field" from "the caller asked for the empty value", and only the
+	// former may inherit. So:
+	//
+	//	nil   → field absent from the request: keep the current value
+	//	&"x"  → present: store exactly "x" (including "" to clear it)
+	//
+	// api_key deliberately keeps its older "empty means inherit" rule rather
+	// than gaining a pointer: that rule is already published (v1.7.6) and
+	// scripts depend on it. Changing it now would let a script that echoes an
+	// empty api_key erase a live credential, which is the exact failure this
+	// whole area exists to prevent.
+	ProxyURL     *string `json:"proxy_url,omitempty"`
+	APIKeyEnv    *string `json:"api_key_env,omitempty"`
+	Timeout      *string `json:"timeout,omitempty"`       // duration string, e.g. "300s"
+	QueueTimeout *string `json:"queue_timeout,omitempty"` // duration string, e.g. "90s"
+}
+
+// optionalSourceFields carries the Source fields a partial payload must not
+// reset, each as a pointer so "absent" and "explicitly empty" stay distinct.
+//
+//	nil  → absent from the request: keep the current value
+//	&""  → present: clear it
+//	&"x" → present: store "x"
+//
+// The alternative — a plain value with "empty means inherit" — cannot express
+// "clear this field", so emptying the proxy input in the UI would silently keep
+// the old proxy. It is exactly why api_key is NOT modelled this way: for a
+// credential, failing to keep the old value is worse than failing to clear it,
+// and that rule is already published (v1.7.6). Two fields with opposite failure
+// modes therefore get opposite rules, and both are spelled out here.
+type optionalSourceFields struct {
+	ProxyURL     *string
+	APIKeyEnv    *string
+	Timeout      *string
+	QueueTimeout *string
+}
+
+// resolve overlays the four optional fields onto payload.
+//
+// A nil pointer means the request did not mention the field, so it keeps the
+// value already stored in cur (nil cur = a source being created, where the
+// payload's own zero value is correct). A non-nil pointer always wins, including
+// when it points at the empty string, which is how a UI form clears a field.
+//
+// Only these four fields are overlaid. Everything else in payload is taken as
+// sent: an upsert that inherited the whole record would make it impossible to
+// change anything.
+func (o optionalSourceFields) resolve(payload config.Source, cur *config.Source) (config.Source, error) {
+	// cur is dereferenced exactly once here so the create path (nil) cannot
+	// panic on the per-field lookups below.
+	var storedProxyURL, storedKeyEnv string
+	var storedTimeout, storedQueueTimeout time.Duration
+	if cur != nil {
+		storedProxyURL, storedKeyEnv = cur.ProxyURL, cur.APIKeyEnv
+		storedTimeout, storedQueueTimeout = cur.Timeout, cur.QueueTimeout
+	}
+	pick := func(p *string, stored string) string {
+		if p != nil {
+			return *p
+		}
+		return stored
+	}
+	payload.ProxyURL = pick(o.ProxyURL, storedProxyURL)
+	payload.APIKeyEnv = pick(o.APIKeyEnv, storedKeyEnv)
+	if err := overlayDuration(&payload.Timeout, o.Timeout, "timeout", storedTimeout); err != nil {
+		return payload, err
+	}
+	if err := overlayDuration(&payload.QueueTimeout, o.QueueTimeout, "queue_timeout", storedQueueTimeout); err != nil {
+		return payload, err
+	}
+	return payload, nil
+}
+
+// overlayDuration applies the absent/present rule to one duration field: a nil
+// pointer keeps stored, a set pointer replaces it (with "" / "0s" clearing).
+func overlayDuration(dst *time.Duration, p *string, field string, stored time.Duration) error {
+	if p == nil {
+		*dst = stored
+		return nil
+	}
+	d, err := parseOptionalDuration(*p, field)
+	if err != nil {
+		return err
+	}
+	*dst = d
+	return nil
+}
+
+// parseOptionalDuration parses a duration written as a Go duration string.
+// An empty string clears the field back to the config default (0), which is
+// what a UI form submitting an empty timeout box should mean. Parsing happens
+// only for fields the request actually mentions, so a typo can never surface
+// as a silent reset of something else.
+func parseOptionalDuration(v, field string) (time.Duration, error) {
+	v = strings.TrimSpace(v)
+	if v == "" {
+		return 0, nil
+	}
+	d, err := time.ParseDuration(v)
+	if err != nil {
+		return 0, fmt.Errorf("%s %q is not a duration (use e.g. 120s, 5m, 1h)", field, v)
+	}
+	if d < 0 {
+		return 0, fmt.Errorf("%s must be >= 0 (got %s)", field, v)
+	}
+	return d, nil
 }
 
 // keepExistingAPIKey is the mask a client sends when it means "keep the
@@ -186,6 +302,21 @@ func (g *Gateway) handleSourcesAPI(w http.ResponseWriter, r *http.Request) {
 			MaxConcurrent: p.MaxConcurrent,
 			RPM:           p.RPM,
 		}
+		// The four upsert-fragile fields are applied last: a nil pointer means
+		// "not in the request", so they are inherited from the stored source
+		// instead of being reset to the payload's zero value. This runs whether
+		// or not the request mentioned them, because resolve() itself decides
+		// per field — passing them unconditionally keeps the rule in one place.
+		src, err := optionalSourceFields{
+			ProxyURL:     p.ProxyURL,
+			APIKeyEnv:    p.APIKeyEnv,
+			Timeout:      p.Timeout,
+			QueueTimeout: p.QueueTimeout,
+		}.resolve(src, g.sourceByName(p.Name))
+		if err != nil {
+			writeError(w, http.StatusBadRequest, "source_error", err.Error())
+			return
+		}
 		// model_ids is additive: "add these models" is the common scripted edit
 		// and it must not require reading (and echoing) the whole list back.
 		// A request that omits models entirely is therefore a pure add, not a
@@ -302,6 +433,32 @@ func (g *Gateway) handleStatsAPI(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 	key := exportKey(r)
+	// ?period=day|week|month|all switches the whole payload to a calendar
+	// window (UTC) aggregated off the audit files, instead of the
+	// since-process-start totals. The CSV exports below are unaffected: they
+	// take an explicit from/to range and stream, so a period selector there
+	// would only be a second way to spell the same bounds.
+	if p := periodFromQuery(r.URL.Query()); p != PeriodAll {
+		if !ValidPeriod(p) {
+			writeError(w, http.StatusBadRequest, "bad_period",
+				"period must be one of day, week, month, all")
+			return
+		}
+		out := g.stats.PeriodSnapshot(p, key, time.Now())
+		writeJSON(w, http.StatusOK, map[string]interface{}{
+			"period":    out.Period,
+			"from":      out.From,
+			"total":     out.Total,
+			"by_key":    out.ByKey,
+			"by_model":  out.Models,
+			"by_source": out.Srcs,
+			"by_status": out.Status,
+			"buckets":   out.Bucket,
+			"truncated": out.Truncated,
+			"key_names": g.keyNamesFor(),
+		})
+		return
+	}
 	if r.URL.Query().Get("export") == "csv" {
 		from, _ := strconv.ParseInt(r.URL.Query().Get("from"), 10, 64)
 		to, _ := strconv.ParseInt(r.URL.Query().Get("to"), 10, 64)
@@ -409,14 +566,22 @@ func (g *Gateway) handleStatsAPI(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	snap := g.stats.Snapshot(limit, key)
-	keyNames := map[string]string{}
+	snap["key_names"] = g.keyNamesFor()
-	for _, k := range g.core.ListKeys() {
-		keyNames[keyID(k.Key)] = k.Name
-	}
-	snap["key_names"] = keyNames
 	writeJSON(w, http.StatusOK, snap)
 }
 
+// keyNamesFor is the masked-id -> display-name map every stats payload needs.
+// It is keyed by keyID (the mask), not the raw key, because that is what the
+// aggregate rows carry — building it in one place stops the period branch and
+// the lifetime branch from drifting apart.
+func (g *Gateway) keyNamesFor() map[string]string {
+	names := map[string]string{}
+	for _, k := range g.core.ListKeys() {
+		names[keyID(k.Key)] = k.Name
+	}
+	return names
+}
+
 // handleStatsRecordsAPI pages the request records straight off the audit files.
 // The dashboard loads only its first screen and asks for the next page as the
 // user scrolls, so neither side holds the full history: the server keeps no

internal/gateway/apiv1.go

@@ -78,7 +78,9 @@ func (g *Gateway) apiV1Routes(w http.ResponseWriter, r *http.Request) {
 							"admin role required to reveal credentials")
 						return
 					}
-					writeJSON(w, http.StatusOK, map[string]interface{}{"source": s})
+					// The edit form round-trips this response, so it needs the credential in the
+					// clear AND the durations — see maskSourceFields.
+					writeJSON(w, http.StatusOK, map[string]interface{}{"source": maskSourceFields(s, true, true)})
 					return
 				}
 				writeJSON(w, http.StatusOK, map[string]interface{}{"source": maskSource(s)})
@@ -176,7 +178,11 @@ func (g *Gateway) apiV1Index(w http.ResponseWriter, r *http.Request) {
 			{Method: "GET", Path: "/api/keys", Auth: "admin", Summary: "gateway keys"},
 			{Method: "POST", Path: "/api/keys", Auth: "admin", Summary: "create a gateway key",
 				WriteEffect: "writes config.yaml"},
-			{Method: "DELETE", Path: "/api/keys/{name}", Auth: "admin", Summary: "delete a gateway key",
+			{Method: "PUT", Path: "/api/keys/{key}", Auth: "admin",
+				Summary:     "update a gateway key (name, role, model scopes and their per-model quotas)",
+				WriteEffect: "writes config.yaml"},
+			{Method: "DELETE", Path: "/api/keys/{key}", Auth: "admin",
+				Summary:     "delete a gateway key — the path segment is the KEY itself, not its name",
 				WriteEffect: "writes config.yaml"},
 
 			{Method: "GET", Path: "/api/status", Auth: "any", Summary: "per-source health detail"},
@@ -194,6 +200,14 @@ func (g *Gateway) apiV1Index(w http.ResponseWriter, r *http.Request) {
 			"partial_update": "api_key may be omitted or sent as the literal \"__KEEP__\" to inherit the " +
 				"current credential; model_ids adds models to the existing list instead of replacing it, " +
 				"so a one-field edit never needs to read the source first",
+			"optional_fields": "proxy_url, api_key_env, timeout and queue_timeout use presence semantics: " +
+				"OMITTED from the request keeps the stored value, present (even as \"\") overwrites it. " +
+				"The upsert rewrites the whole source, so without this a one-field edit would silently reset " +
+				"them — and api_key_env in particular is only visible as a credential failure on the NEXT " +
+				"upstream call. api_key deliberately keeps the older \"empty means inherit\" rule instead, " +
+				"because losing a credential breaks the source while losing a proxy only changes its route.",
+			"durations": "timeout and queue_timeout are Go duration strings (\"300s\", \"5m\", \"1h\"); " +
+				"the empty string clears them back to the config defaults",
 			"config_truth": "all configuration lives in config.yaml; API writes are persisted immediately",
 			"credentials": "credentials are masked by default. GET /api/v1/sources/{name}?reveal=credentials " +
 				"returns them in the clear and is admin-only — the Web UI edit dialog uses it, because a form " +
@@ -294,23 +308,48 @@ func maskSources(srcs []config.Source) []map[string]interface{} {
 }
 
 func maskSource(s config.Source) map[string]interface{} {
-	return map[string]interface{}{
+	return maskSourceFields(s, false, false)
+}
+
+// maskSourceFields builds the API view of a source.
+//
+// revealCredentials swaps the masked api_key for the real one — admin-only, and
+// used by the WebUI edit dialog, whose form has to round-trip the whole source
+// or saving an unrelated field would blank the key.
+//
+// exposeDurations adds the two durations as strings, matching what the write
+// path accepts. It rides along with the credential reveal because both exist for
+// the same reason: config.Source tags Timeout/QueueTimeout `json:"-"`, so a
+// plain marshal of the struct omits them. A form that cannot SEE the stored
+// timeout would clear it on every save, since the timeout box is always sent.
+func maskSourceFields(s config.Source, revealCredentials, exposeDurations bool) map[string]interface{} {
+	key := maskKey(s.APIKey)
+	if revealCredentials {
+		key = s.APIKey
+	}
+	m := map[string]interface{}{
 		"name":           s.Name,
 		"base_url":       s.BaseURL,
 		"adapter":        s.Adapter,
 		"endpoint":       s.Endpoint,
 		"image_endpoint": s.ImageEndpoint,
-		"api_key":        maskKey(s.APIKey),
+		"api_key":        key,
 		"api_key_set":    s.APIKey != "",
 		"models":         s.Models,
 		"headers":        maskHeaders(s.Headers),
 		"proxy_url":      s.ProxyURL,
+		"api_key_env":    s.APIKeyEnv,
 		"meta":           s.Meta,
 		"temperature":    s.Temperature,
 		"max_tokens":     s.MaxTokens,
 		"max_concurrent": s.MaxConcurrent,
 		"rpm":            s.RPM,
 	}
+	if exposeDurations {
+		m["timeout"] = s.Timeout.String()
+		m["queue_timeout"] = s.QueueTimeout.String()
+	}
+	return m
 }
 
 func maskKey(k string) string {

internal/gateway/billing_rules_api.go

@@ -0,0 +1,282 @@
+package gateway
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"llmsproxy/internal/billing"
+	"llmsproxy/internal/config"
+)
+
+// Billing rules API.
+//
+//	GET  /api/plugins/billing/rules    the active profile's rules + all profiles
+//	PUT  /api/plugins/billing/rules    replace the whole DSL and re-inject prices
+//	POST /api/plugins/billing/rules    { profile, rule } append one rule
+//	DELETE /api/plugins/billing/rules  { profile, url } remove one rule
+//
+// Why a separate endpoint instead of the generic plugin state: prices are
+// plugin state, but they are also a durable, reviewable CONFIGURATION. Routing
+// them through /state would let an admin key PUT arbitrary plugin state and
+// silently reset the accumulated accounting. Here the server owns the shape:
+// it validates the DSL, writes it back to config.yaml, recompiles, and hands
+// the plugin its prices table. The operator edits rules; the plugin keeps
+// numbers. The two are never mixed in one payload.
+//
+// Editing means "what the operator typed is what config.yaml holds". A
+// billing mistake found next week must be traceable to a reviewable file, not
+// to a blob in the plugin's state sidecar.
+func (g *Gateway) handleBillingRules(w http.ResponseWriter, r *http.Request) {
+	if reqRole(r.Context()) != "admin" {
+		writeError(w, http.StatusForbidden, "forbidden", "admin role required")
+		return
+	}
+	switch r.Method {
+	case http.MethodGet:
+		g.getBillingRules(w)
+	case http.MethodPut:
+		g.putBillingRules(w, r)
+	case http.MethodPost:
+		g.addBillingRule(w, r)
+	case http.MethodDelete:
+		g.delBillingRule(w, r)
+	default:
+		writeError(w, http.StatusMethodNotAllowed, "method_not_allowed", "use GET/PUT/POST/DELETE")
+	}
+}
+
+// billingRulesPayload is the UI-facing view: the profiles as declared, plus
+// which one is active and the source URLs they can match — the editor needs
+// the URL list to offer suggestions, and an operator typing a URL that matches
+// no source is exactly the silent-no-pricing failure this feature exists to
+// remove.
+type billingRulesPayload struct {
+	DSL      *config.BillingDSL `json:"billing"`
+	Active   string             `json:"active"`
+	URLs     []string           `json:"urls"`
+	Warnings []string           `json:"warnings"`
+}
+
+func (g *Gateway) billingRulesPayload() billingRulesPayload {
+	out := billingRulesPayload{}
+	cfg := g.core.Config()
+	if cfg != nil && cfg.BillingDSL != nil {
+		// Copy so the response cannot be mutated back through the pointer.
+		cp := *cfg.BillingDSL
+		out.DSL = &cp
+		if p := cp.Resolve(""); p != nil {
+			out.Active = p.ID
+		}
+	}
+	for _, s := range g.sourceURLs() {
+		out.URLs = append(out.URLs, s)
+	}
+	out.Warnings = g.billingRuleWarnings()
+	return out
+}
+
+func (g *Gateway) sourceURLs() []string {
+	cfg := g.core.Config()
+	if cfg == nil {
+		return nil
+	}
+	seen := map[string]bool{}
+	var out []string
+	for _, s := range cfg.Sources {
+		if s.BaseURL == "" || seen[s.BaseURL] {
+			continue
+		}
+		seen[s.BaseURL] = true
+		out = append(out, s.BaseURL)
+	}
+	return out
+}
+
+// billingRuleWarnings reports rules that match no configured source. This is
+// the silent killer of hand-written price tables: the rule parses, validates,
+// and prices nothing at all, so every request on that URL lands in unpriced.
+// Saying so out loud is the difference between a five-second fix and an
+// afternoon wondering why the bill is zero.
+func (g *Gateway) billingRuleWarnings() []string {
+	cfg := g.core.Config()
+	if cfg == nil || cfg.BillingDSL == nil {
+		return nil
+	}
+	urls := map[string]bool{}
+	for _, u := range g.sourceURLs() {
+		urls[u] = true
+	}
+	var warns []string
+	for _, p := range cfg.BillingDSL.Profiles {
+		for _, r := range p.Rules {
+			if r.URL == "*" || urls[r.URL] {
+				continue
+			}
+			warns = append(warns, "profile "+p.ID+": rule url "+r.URL+" matches no configured source")
+		}
+	}
+	return warns
+}
+
+func (g *Gateway) getBillingRules(w http.ResponseWriter) {
+	writeJSON(w, http.StatusOK, g.billingRulesPayload())
+}
+
+func (g *Gateway) putBillingRules(w http.ResponseWriter, r *http.Request) {
+	var body struct {
+		Billing *config.BillingDSL `json:"billing"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid_request", "invalid json: "+err.Error())
+		return
+	}
+	if body.Billing == nil {
+		writeError(w, http.StatusBadRequest, "invalid_request", "billing is required")
+		return
+	}
+	g.applyBillingDSLUpdate(w, body.Billing)
+}
+
+func (g *Gateway) addBillingRule(w http.ResponseWriter, r *http.Request) {
+	var body struct {
+		Profile string             `json:"profile"`
+		Rule    config.BillingRule `json:"rule"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid_request", "invalid json: "+err.Error())
+		return
+	}
+	cfg := g.core.Config()
+	if cfg == nil || cfg.BillingDSL == nil || len(cfg.BillingDSL.Profiles) == 0 {
+		writeError(w, http.StatusBadRequest, "no_profile", "no billing profiles configured; create one first")
+		return
+	}
+	next := cloneBillingDSL(cfg.BillingDSL)
+	idx := profileIndex(next, body.Profile)
+	if idx < 0 {
+		writeError(w, http.StatusBadRequest, "unknown_profile", "no such profile: "+body.Profile)
+		return
+	}
+	p := &next.Profiles[idx]
+	// Replace rather than append when the URL is already declared: two rules
+	// for one URL would silently make the first unreachable (first match wins),
+	// which is the exact ambiguity an editor should not be able to create.
+	replaced := false
+	for i := range p.Rules {
+		if p.Rules[i].URL == body.Rule.URL {
+			p.Rules[i] = body.Rule
+			replaced = true
+			break
+		}
+	}
+	if !replaced {
+		p.Rules = append(p.Rules, body.Rule)
+	}
+	g.applyBillingDSLUpdate(w, next)
+}
+
+func (g *Gateway) delBillingRule(w http.ResponseWriter, r *http.Request) {
+	var body struct {
+		Profile string `json:"profile"`
+		URL     string `json:"url"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid_request", "invalid json: "+err.Error())
+		return
+	}
+	cfg := g.core.Config()
+	if cfg == nil || cfg.BillingDSL == nil {
+		writeError(w, http.StatusBadRequest, "no_profile", "no billing profiles configured")
+		return
+	}
+	next := cloneBillingDSL(cfg.BillingDSL)
+	idx := profileIndex(next, body.Profile)
+	if idx < 0 {
+		writeError(w, http.StatusBadRequest, "unknown_profile", "no such profile: "+body.Profile)
+		return
+	}
+	p := &next.Profiles[idx]
+	out := p.Rules[:0]
+	found := false
+	for _, rule := range p.Rules {
+		if rule.URL == body.URL {
+			found = true
+			continue
+		}
+		out = append(out, rule)
+	}
+	if !found {
+		writeError(w, http.StatusNotFound, "not_found", "no rule for url "+body.URL)
+		return
+	}
+	p.Rules = out
+	g.applyBillingDSLUpdate(w, next)
+}
+
+// applyBillingDSLUpdate is the single write path: validate, persist to
+// config.yaml, recompile, inject, and only then report success. If the config
+// cannot be written the change is NOT applied in memory either — a rules editor
+// that says "saved" and loses the edit on the next restart is worse than one
+// that refuses.
+func (g *Gateway) applyBillingDSLUpdate(w http.ResponseWriter, next *config.BillingDSL) {
+	if err := next.Validate(); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid_rules", err.Error())
+		return
+	}
+	cfg := g.core.Config()
+	if cfg == nil {
+		writeError(w, http.StatusInternalServerError, "no_config", "no config loaded")
+		return
+	}
+	// Assign BEFORE saving. The previous order saved first and assigned after,
+	// so every rule edit reported success while writing a config.yaml with no
+	// billing section at all — the operator's edit vanished on restart and
+	// nothing in the API response said so.
+	prev := cfg.BillingDSL
+	cfg.BillingDSL = next
+
+	// Compile before persisting: a profile that cannot be turned into prices
+	// must not reach the config file, or the next restart fails to load the
+	// very rules the editor just accepted.
+	prices, err := billing.CompileOpts(next.Resolve(next.Active), cfg.Sources, true)
+	if err != nil {
+		cfg.BillingDSL = prev // no half-applied state
+		writeError(w, http.StatusBadRequest, "compile_failed", err.Error())
+		return
+	}
+	if err := cfg.Save(); err != nil {
+		cfg.BillingDSL = prev
+		writeError(w, http.StatusInternalServerError, "persist_failed", err.Error())
+		return
+	}
+	ps := g.core.Plugins()
+	if ps != nil {
+		if err := ps.SetState("billing", map[string]interface{}{"prices": prices}); err != nil {
+			writeError(w, http.StatusBadRequest, "plugin_error", err.Error())
+			return
+		}
+	}
+	p := g.billingRulesPayload()
+	writeJSON(w, http.StatusOK, map[string]interface{}{
+		"ok": true, "billing": p.DSL, "active": p.Active, "warnings": p.Warnings,
+	})
+}
+
+func cloneBillingDSL(d *config.BillingDSL) *config.BillingDSL {
+	out := &config.BillingDSL{Active: d.Active}
+	out.Profiles = make([]config.BillingProfile, len(d.Profiles))
+	copy(out.Profiles, d.Profiles)
+	return out
+}
+
+func profileIndex(d *config.BillingDSL, id string) int {
+	if id == "" {
+		return -1
+	}
+	for i, p := range d.Profiles {
+		if p.ID == id {
+			return i
+		}
+	}
+	return -1
+}

internal/gateway/billing_rules_api_test.go

@@ -0,0 +1,281 @@
+package gateway
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"sort"
+	"strings"
+	"testing"
+
+	"llmsproxy/internal/config"
+)
+
+// rulesGateway needs a real billing plugin (the API injects prices into it)
+// AND two sources whose base_urls the rules will match, so it cannot reuse
+// either existing helper: gatewayWithBilling has no sources, and
+// newTestGateway loads no plugins.
+func rulesGateway(t *testing.T) *Gateway {
+	t.Helper()
+	g := gatewayWithBilling(t)
+	cfg := g.core.Config()
+	cfg.Sources = []config.Source{
+		{Name: "localzen", BaseURL: "https://free.example.com/v1"},
+		{Name: "commandcode", BaseURL: "https://api.commandcode.ai/v1"},
+	}
+	return g
+}
+
+func rulesDo(t *testing.T, g *Gateway, method, body string) *httptest.ResponseRecorder {
+	t.Helper()
+	return doReq(t, g, method, "/api/plugins/billing/rules", body)
+}
+
+// TestBillingRulesCRUD covers the whole editor loop against the real HTTP
+// surface: read, add, replace-by-URL, delete. The replace-by-URL case is the
+// one worth pinning — two rules for one URL would make the first unreachable
+// (first match wins) without any error, which is exactly the kind of silent
+// ambiguity an editor must not be able to create.
+func TestBillingRulesCRUD(t *testing.T) {
+	g := rulesGateway(t)
+	seed := `{"billing":{"active":"p1","profiles":[{"id":"p1","rules":[
+      {"url":"https://free.example.com/v1","mode":"free"}]}]}}`
+	if rr := rulesDo(t, g, http.MethodPut, seed); rr.Code != http.StatusOK {
+		t.Fatalf("seed rules = %d: %s", rr.Code, rr.Body.String())
+	}
+
+	// Add a token-priced rule for the second URL.
+	add := `{"profile":"p1","rule":{"url":"https://api.commandcode.ai/v1","mode":"token",
+      "models":{"deepseek-v4.1-flash":{"prompt":"0.15","completion":"0.60"}}}}`
+	if rr := rulesDo(t, g, http.MethodPost, add); rr.Code != http.StatusOK {
+		t.Fatalf("add rule = %d: %s", rr.Code, rr.Body.String())
+	}
+	var got billingRulesPayload
+	if err := json.Unmarshal(rulesDo(t, g, http.MethodGet, "").Body.Bytes(), &got); err != nil {
+		t.Fatal(err)
+	}
+	if len(got.DSL.Profiles[0].Rules) != 2 {
+		t.Fatalf("after add there are %d rules, want 2", len(got.DSL.Profiles[0].Rules))
+	}
+
+	// Adding the SAME url again must replace, not append.
+	if rr := rulesDo(t, g, http.MethodPost, `{"profile":"p1","rule":{"url":"https://api.commandcode.ai/v1","mode":"free"}}`); rr.Code != http.StatusOK {
+		t.Fatalf("re-add same url = %d: %s", rr.Code, rr.Body.String())
+	}
+	if err := json.Unmarshal(rulesDo(t, g, http.MethodGet, "").Body.Bytes(), &got); err != nil {
+		t.Fatal(err)
+	}
+	if n := len(got.DSL.Profiles[0].Rules); n != 2 {
+		t.Fatalf("★ re-adding an existing url appended instead of replacing: %d rules", n)
+	}
+	var mode string
+	for _, r := range got.DSL.Profiles[0].Rules {
+		if r.URL == "https://api.commandcode.ai/v1" {
+			mode = r.Mode
+		}
+	}
+	if mode != "free" {
+		t.Errorf("re-added rule mode = %q, want free (the replacement must win)", mode)
+	}
+
+	// Delete by URL.
+	if rr := rulesDo(t, g, http.MethodDelete, `{"profile":"p1","url":"https://api.commandcode.ai/v1"}`); rr.Code != http.StatusOK {
+		t.Fatalf("delete rule = %d: %s", rr.Code, rr.Body.String())
+	}
+	if err := json.Unmarshal(rulesDo(t, g, http.MethodGet, "").Body.Bytes(), &got); err != nil {
+		t.Fatal(err)
+	}
+	if len(got.DSL.Profiles[0].Rules) != 1 {
+		t.Errorf("after delete there are %d rules, want 1", len(got.DSL.Profiles[0].Rules))
+	}
+}
+
+// TestBillingRulesRejectUnknownURLWithWarning is the silent-failure guard: a
+// rule whose URL matches no source prices nothing, so every request on it
+// falls into unpriced. The API must say so instead of accepting it silently.
+func TestBillingRulesRejectUnknownURLWithWarning(t *testing.T) {
+	g := rulesGateway(t)
+	if rr := rulesDo(t, g, http.MethodPut, `{"billing":{"active":"p","profiles":[{"id":"p",
+      "rules":[{"url":"https://typo.example.com/v1","mode":"free"}]}]}}`); rr.Code != http.StatusOK {
+		t.Fatalf("seed = %d: %s", rr.Code, rr.Body.String())
+	}
+	var got billingRulesPayload
+	if err := json.Unmarshal(rulesDo(t, g, http.MethodGet, "").Body.Bytes(), &got); err != nil {
+		t.Fatal(err)
+	}
+	if len(got.Warnings) == 0 {
+		t.Fatal("★ a rule matching no configured source was accepted with no warning — " +
+			"it will price nothing and every request will be recorded as unpriced")
+	}
+	if !strings.Contains(got.Warnings[0], "typo.example.com") {
+		t.Errorf("warning does not name the offending url: %v", got.Warnings)
+	}
+	// The editor needs the real URL list to offer suggestions.
+	if len(got.URLs) != 2 {
+		t.Errorf("urls offered to the editor = %v, want the 2 configured base_urls", got.URLs)
+	}
+}
+
+// TestBillingRulesInvalidIsRejectedNotPersisted checks the write path refuses
+// bad input and leaves the previous rules in place — an editor that clears the
+// table on a typo loses the price table.
+func TestBillingRulesInvalidIsRejectedNotPersisted(t *testing.T) {
+	g := rulesGateway(t)
+	seed := `{"billing":{"active":"p","profiles":[{"id":"p","rules":[
+      {"url":"https://free.example.com/v1","mode":"free"}]}]}}`
+	if rr := rulesDo(t, g, http.MethodPut, seed); rr.Code != http.StatusOK {
+		t.Fatalf("seed = %d: %s", rr.Code, rr.Body.String())
+	}
+	// An unknown mode must be refused.
+	if rr := rulesDo(t, g, http.MethodPost, `{"profile":"p","rule":{"url":"https://x/v1","mode":"banana"}}`); rr.Code != http.StatusBadRequest {
+		t.Errorf("invalid mode accepted with %d, want 400", rr.Code)
+	}
+	var got billingRulesPayload
+	if err := json.Unmarshal(rulesDo(t, g, http.MethodGet, "").Body.Bytes(), &got); err != nil {
+		t.Fatal(err)
+	}
+	if len(got.DSL.Profiles[0].Rules) != 1 {
+		t.Errorf("★ a rejected rule was persisted anyway: %d rules", len(got.DSL.Profiles[0].Rules))
+	}
+	// An unparseable price must be refused too, not silently priced at zero.
+	if rr := rulesDo(t, g, http.MethodPost, `{"profile":"p","rule":{"url":"https://y/v1","mode":"token",
+      "models":{"m":{"prompt":"free","completion":"0.6"}}}}`); rr.Code != http.StatusBadRequest {
+		t.Errorf("non-numeric price accepted with %d, want 400", rr.Code)
+	}
+}
+
+// TestBillingRulesPersistAndReachThePlugin is the point of the whole
+// endpoint, and mutation verification showed the earlier CRUD tests missed it
+// twice: dropping cfg.Save() and dropping the SetState injection both left
+// every test green. Both failures are invisible in a GET — the response echoes
+// the in-memory rules either way — so this test checks the two consequences
+// that actually matter:
+//
+//  1. persistence: the rule must be in the config file on disk, because an
+//     edit that evaporates on restart is a lie the UI told the operator;
+//  2. effect: the billing plugin must now PRICE the source (its published
+//     prices table has a non-zero entry), because a rule that is stored but
+//     never injected prices nothing at all.
+func TestBillingRulesPersistAndReachThePlugin(t *testing.T) {
+	g := rulesGateway(t)
+	cfg := g.core.Config()
+
+	seed := `{"billing":{"active":"p","profiles":[{"id":"p","rules":[
+      {"url":"https://free.example.com/v1","mode":"free"},
+      {"url":"https://api.commandcode.ai/v1","mode":"token",
+       "models":{"deepseek-v4.1-flash":{"prompt":"0.15","completion":"0.60"}}}]}]}}`
+	if rr := rulesDo(t, g, http.MethodPut, seed); rr.Code != http.StatusOK {
+		t.Fatalf("seed = %d: %s", rr.Code, rr.Body.String())
+	}
+
+	// 1. persisted to the file the process loaded from.
+	raw, err := os.ReadFile(cfg.Path)
+	if err != nil {
+		t.Fatalf("read config: %v", err)
+	}
+	if !strings.Contains(string(raw), "commandcode.ai") {
+		t.Errorf("★ the rule is not in config.yaml on disk — an edit that does not "+
+			"survive a restart:\n%s", raw)
+	}
+	reloaded, err := config.Load(cfg.Path)
+	if err != nil {
+		t.Fatalf("reload saved config: %v", err)
+	}
+	if reloaded.BillingDSL == nil || len(reloaded.BillingDSL.Profiles) == 0 {
+		t.Fatalf("saved config has no billing DSL: %s", raw)
+	}
+	// A round-trip through YAML must not lose the price strings.
+	found := false
+	for _, r := range reloaded.BillingDSL.Profiles[0].Rules {
+		if strings.Contains(r.URL, "commandcode") {
+			found = true
+			if m, ok := r.Models["deepseek-v4.1-flash"]; !ok || m.Prompt != "0.15" {
+				t.Errorf("price did not survive the YAML round-trip: %+v", m)
+			}
+		}
+	}
+	if !found {
+		t.Errorf("the token rule is missing after reload:\n%s", raw)
+	}
+
+	// 2. reached the plugin. Prices live in a separate Lua field from `state`,
+	// and the GET /state endpoint returns the published state together with
+	// the prices sidecar — which is exactly what the plugin's own UI reads.
+	state := g.core.Plugins().State("billing")
+	if state == nil {
+		t.Fatalf("billing plugin published no state")
+	}
+	rr := doReq(t, g, http.MethodGet, "/api/plugins/billing/state", "")
+	if rr.Code != http.StatusOK {
+		t.Fatalf("GET state = %d: %s", rr.Code, rr.Body.String())
+	}
+	var envelope struct {
+		Prices map[string]interface{} `json:"prices"`
+	}
+	if err := json.Unmarshal(rr.Body.Bytes(), &envelope); err != nil {
+		t.Fatalf("decode state envelope: %v", err)
+	}
+	prices := envelope.Prices
+	if prices == nil {
+		t.Fatalf("state payload carries no prices")
+	}
+	sources, ok := prices["sources"].(map[string]interface{})
+	if !ok {
+		t.Fatalf("prices has no sources map: %#v", prices)
+	}
+	cc, ok := sources["commandcode"]
+	if !ok {
+		t.Fatalf("★ the rule was saved but never injected: prices has %v, "+
+			"no commandcode entry. Every request on it stays unpriced.", keysOf(sources))
+	}
+	if cc == nil {
+		t.Error("commandcode price entry is nil")
+	}
+	// The free rule must price localzen, and the two must not be conflated.
+	if _, ok := sources["localzen"]; !ok {
+		t.Errorf("the free rule did not reach the plugin: %v", keysOf(sources))
+	}
+	// The injected price must be per-token, i.e. 0.15 USD/M => 1.5e-7.
+	// Asserting the exact magnitude catches a unit error (per-million vs
+	// per-token), which would be off by a factor of a million and still look
+	// like "a number".
+	models, ok := cc.(map[string]interface{})["models"].(map[string]interface{})
+	if ok {
+		if m, ok := models["deepseek-v4.1-flash"].(map[string]interface{}); ok {
+			p, _ := m["prompt"].(float64)
+			if p <= 0 || p > 1e-6 {
+				t.Errorf("injected prompt price = %v, want per-token (~1.5e-7); "+
+					"a per-million value here would over-bill by 1e6x", p)
+			}
+		}
+	}
+}
+
+func keysOf(m map[string]interface{}) []string {
+	out := make([]string, 0, len(m))
+	for k := range m {
+		out = append(out, k)
+	}
+	sort.Strings(out)
+	return out
+}
+
+// TestBillingRulesRequireAdmin keeps price rewriting behind the admin role,
+// like every other plugin write: prices are configuration, not user data.
+func TestBillingRulesRequireAdmin(t *testing.T) {
+	g := rulesGateway(t)
+	rec, err := g.core.CreateKey("viewer", "user", nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	userKey := rec.Key
+	for _, m := range []string{http.MethodPut, http.MethodPost, http.MethodDelete} {
+		req, _ := http.NewRequest(m, "/api/plugins/billing/rules", strings.NewReader(`{}`))
+		req.Header.Set("Authorization", "Bearer "+userKey)
+		req.Header.Set("Content-Type", "application/json")
+		if rr := newRecorderFor(t, g, req); rr.Code != http.StatusForbidden {
+			t.Errorf("user %s rules = %d, want 403", m, rr.Code)
+		}
+	}
+}

internal/gateway/chat.go

@@ -14,6 +14,7 @@ import (
 	"time"
 
 	"llmsproxy/internal/config"
+	"llmsproxy/internal/lua"
 	"llmsproxy/internal/provider"
 	"llmsproxy/internal/scheduler"
 	"llmsproxy/internal/types"
@@ -385,6 +386,19 @@ func (g *Gateway) handleChat(w http.ResponseWriter, r *http.Request) {
 	if model == "" {
 		model = g.core.DefaultModel()
 	}
+	// request_start fires for EVERY chat request, on both the AUTO and the
+	// direct path, and it fires BEFORE the quota / model-scope gates on
+	// purpose: a plugin that counts volume or audits traffic must also see the
+	// requests the gateway rejected, otherwise "requests accepted" would be all
+	// it could ever report. It sits after authentication (so the key and role in
+	// the payload are real) and after the messages check (a body with no
+	// messages is not a chat request at all).
+	//
+	// Calling it here rather than inside each branch is what keeps the two paths
+	// honest: an earlier version called it only from the AUTO branch, so every
+	// direct (model-pinned) request silently skipped it. That was caught by
+	// TestHooksFireOnRealDirectChat, not by reading the code.
+	g.fireStart(r.Context(), &req, "chat", model, len(req.Messages), len(req.Tools))
 	if isAuto(model) {
 		chain := g.core.AutoChain()
 		if chain == nil || len(chain.Tiers) == 0 {
@@ -817,6 +831,7 @@ func (g *Gateway) singleChat(w http.ResponseWriter, ctx context.Context, cands [
 	recordChatUsage(rec, req, resp)
 	rec.Source = usedSrc
 	rec.Model = usedModel
+	g.fireRouted(ctx, "chat", usedSrc, usedModel, -1, false)
 	// Non-streaming: the whole response arrives at once, so TTFB equals
 	// the total latency.
 	rec.FirstByteMs = rec.LatMs
@@ -824,7 +839,18 @@ func (g *Gateway) singleChat(w http.ResponseWriter, ctx context.Context, cands [
 	writeChatCompletion(w, resp, effective)
 }
 
-// writeRec records a finished request (audit + aggregates).
+// writeRec records a finished request (audit + aggregates) and fires the
+// plugin request_end stage.
+//
+// This is the ONE place every request passes through on its way out, which is
+// what makes it the right hook point: the four entry points (single/stream ×
+// direct/auto) all funnel here, so a plugin sees each request exactly once with
+// its final accounting. Firing earlier would miss the streamed ones (their
+// numbers are only known once the stream finishes), and firing in each entry
+// point would mean four call sites to keep in sync.
+//
+// Hooks run AFTER the record is written: a plugin must not be able to delay or
+// lose the audit trail, and a plugin that throws is contained by Fire.
 func (g *Gateway) writeRec(rec *Req) {
 	if rec == nil {
 		return
@@ -833,6 +859,191 @@ func (g *Gateway) writeRec(rec *Req) {
 		rec.Time = time.Now().UnixMilli()
 	}
 	g.stats.Record(*rec)
+	g.fireEnd(rec)
+}
+
+// fireStart dispatches the plugin request_start stage: the request has been
+// parsed and authorized but no upstream slot has been chosen yet, so `source`
+// is empty. A plugin that only wants volume/acceptance counts can subscribe
+// here and stay out of the per-request hot path entirely.
+func (g *Gateway) fireStart(ctx context.Context, req *chatRequest, kind, model string, msgs, tools int) {
+	ps := g.core.Plugins()
+	if ps == nil || ps.Count() == 0 {
+		return
+	}
+	ps.Fire(lua.StageRequestStart, map[string]interface{}{
+		"stage":          string(lua.StageRequestStart),
+		"type":           kind,
+		"model":          model,
+		"key":            keyID(reqKey(ctx)),
+		"role":           reqRole(ctx),
+		"source":         "",
+		"stream":         req.Stream,
+		"messages_count": msgs,
+		"tools_count":    tools,
+		"ts":             time.Now().Unix(),
+	})
+}
+
+// fireImageStart dispatches request_start for /v1/images/generations.
+//
+// It is a separate function rather than a call to fireStart with a nil
+// chatRequest because the image body has no messages and no tools: passing
+// zeroes through a struct built for chat would invite someone to read a field
+// that simply does not exist on this path.
+func (g *Gateway) fireImageStart(ctx context.Context, model string) {
+	ps := g.core.Plugins()
+	if ps == nil || ps.Count() == 0 {
+		return
+	}
+	ps.Fire(lua.StageRequestStart, map[string]interface{}{
+		"stage":          string(lua.StageRequestStart),
+		"type":           "image",
+		"model":          model,
+		"key":            keyID(reqKey(ctx)),
+		"role":           reqRole(ctx),
+		"source":         "",
+		"stream":         false,
+		"messages_count": 0,
+		"tools_count":    0,
+		"ts":             time.Now().Unix(),
+	})
+}
+
+// fireRouted dispatches the plugin routed stage once a (source, model) slot has
+// been selected. tier is the AUTO tier index, or -1 on the direct path, so a
+// plugin can tell "this came from tier 1" from "this bypassed the chain".
+func (g *Gateway) fireRouted(ctx context.Context, kind, source, model string, tier int, stream bool) {
+	ps := g.core.Plugins()
+	if ps == nil || ps.Count() == 0 {
+		return
+	}
+	ps.Fire(lua.StageRouted, map[string]interface{}{
+		"stage":  string(lua.StageRouted),
+		"type":   kind,
+		"source": source,
+		"model":  model,
+		"key":    keyID(reqKey(ctx)),
+		"tier":   tier,
+		"stream": stream,
+		"ts":     time.Now().Unix(),
+	})
+}
+
+// chainTraceSink adapts a scheduler TraceSink into the plugin chain_step stage.
+//
+// It returns nil when no plugin is loaded, so the scheduler's emit() does a
+// single nil check per event and the AUTO hot path pays nothing on a gateway
+// with no plugins.
+//
+// The events are also accumulated into walk so request_end can carry a compact
+// summary: a plugin that only listens to request_end still learns that a
+// degradation happened, which is the common case for a dashboard that does not
+// want to subscribe to a high-frequency stage.
+func (g *Gateway) chainTraceSink(ctx context.Context, kind string, walk *[]map[string]interface{}) scheduler.TraceSink {
+	ps := g.core.Plugins()
+	if ps == nil || ps.Count() == 0 {
+		return nil
+	}
+	key := keyID(reqKey(ctx))
+	return func(ev scheduler.TraceEvent) {
+		payload := map[string]interface{}{
+			"stage":   string(lua.StageChainStep),
+			"kind":    string(ev.Kind),
+			"type":    kind,
+			"key":     key,
+			"tier":    ev.Tier,
+			"attempt": ev.Attempt,
+		}
+		if ev.Source != "" {
+			payload["source"] = ev.Source
+		}
+		if ev.Model != "" {
+			payload["model"] = ev.Model
+		}
+		if ev.Reason != "" {
+			payload["reason"] = ev.Reason
+		}
+		if ev.Err != "" {
+			payload["error"] = ev.Err
+		}
+		if walk != nil {
+			// Keep the summary bounded: a pathological chain could emit many
+			// steps, and request_end's payload is written to the audit trail.
+			if len(*walk) < maxWalkSummary {
+				*walk = append(*walk, map[string]interface{}{
+					"kind": string(ev.Kind), "tier": ev.Tier,
+					"source": ev.Source, "model": ev.Model, "reason": ev.Reason,
+				})
+			}
+		}
+		ps.Fire(lua.StageChainStep, payload)
+	}
+}
+
+// maxWalkSummary caps how many chain steps request_end carries, so a long
+// degradation cannot inflate every audit record.
+const maxWalkSummary = 12
+
+// tierServed returns the AUTO tier that actually served the request, or -1 when
+// the walk is empty (a direct request) or ended without a selection (total
+// failure). It is the single most useful number for "why did my expensive tier
+// not get used".
+func tierServed(walk []map[string]interface{}) int {
+	for i := len(walk) - 1; i >= 0; i-- {
+		if k, _ := walk[i]["kind"].(string); k == string(scheduler.TraceSelected) {
+			if t, ok := walk[i]["tier"].(int); ok {
+				return t
+			}
+		}
+	}
+	return -1
+}
+
+// fireEnd dispatches the plugin request_end stage for one finished request.
+func (g *Gateway) fireEnd(rec *Req) {
+	ps := g.core.Plugins()
+	if ps == nil || ps.Count() == 0 {
+		return
+	}
+	payload := map[string]interface{}{
+		"stage":             string(lua.StageRequestEnd),
+		"type":              rec.Type,
+		"model":             rec.Model,
+		"source":            rec.Source,
+		"key":               rec.Key,
+		"ok":                rec.OK,
+		"status":            rec.Status,
+		"latency_ms":        rec.LatMs,
+		"first_byte_ms":     rec.FirstByteMs,
+		"prompt_tokens":     rec.Prompt,
+		"completion_tokens": rec.Compl,
+		"cache_hit_tokens":  rec.CacheHit,
+		"cache_miss_tokens": rec.CacheMiss,
+		// Whether UPSTREAM reported a cache number at all. A plugin cannot
+		// infer this from cache_hit_tokens alone: zero hits because nothing was
+		// cached and zero hits because the provider never reports caching are
+		// the same value, and they mean opposite things when you are checking
+		// whether a cache discount is doing anything. The audit record already
+		// carried this (rec.CacheReported); the plugin payload did not, so any
+		// plugin-level cache accounting had to guess.
+		"cache_reported": rec.CacheReported,
+		"image_count":    rec.ImageCount,
+		"error":          rec.Err,
+		"time":           rec.Time,
+		// chain_walk: the AUTO tier-by-tier trace, when the request went
+		// through the chain. Empty for a direct request and for a gateway with
+		// no plugins loaded. Absent rather than empty so a plugin can tell
+		// "no chain" from "chain with no degradation".
+		"degraded":    len(rec.Walk) > 1,
+		"chain_walk":  rec.Walk,
+		"tier_served": tierServed(rec.Walk),
+	}
+	// The merged result is intentionally discarded: request_end is the last
+	// stage, so there is nobody downstream to read a plugin's additions. Plugins
+	// that need to publish derived numbers (the billing plugin) do it in their
+	// OWN state and expose them through the /api/plugins/<name>/state endpoint.
+	ps.Fire(lua.StageRequestEnd, payload)
 }
 
 // mergeUsage combines token usage across stream chunks additively. Some
@@ -1039,6 +1250,7 @@ func (g *Gateway) streamChat(w http.ResponseWriter, ctx context.Context, cands [
 	// failover it differs from the first candidate). Direct streams previously
 	// discarded it.
 	rec.Source = usedSrc
+	g.fireRouted(ctx, "stream", usedSrc, rec.Model, -1, true)
 	rec.Prompt = estimatePromptTokens(req)
 	g.pumpStream(w, rec, chunks, effective, t0)
 }
@@ -1052,8 +1264,11 @@ func (g *Gateway) streamChat(w http.ResponseWriter, ctx context.Context, cands [
 func (g *Gateway) singleChatAuto(w http.ResponseWriter, ctx context.Context, chain *scheduler.Chain, req *types.ChatRequest, rec *Req, quotaExhausted func(*scheduler.Slot) bool) {
 	rec.LatMs = 0
 	t0 := time.Now()
-	resp, usedSrc, usedModel, err := g.core.Scheduler().ChainChat(ctx, chain, req, quotaExhausted)
+	var walk []map[string]interface{}
+	resp, usedSrc, usedModel, err := g.core.Scheduler().ChainChat(ctx, chain, req, quotaExhausted,
+		g.chainTraceSink(ctx, "chat", &walk))
 	rec.LatMs = time.Since(t0).Milliseconds()
+	rec.Walk = walk
 	if err != nil {
 		g.failChat(w, rec, err)
 		g.writeRec(rec)
@@ -1064,6 +1279,10 @@ func (g *Gateway) singleChatAuto(w http.ResponseWriter, ctx context.Context, cha
 	recordChatUsage(rec, req, resp)
 	rec.Source = usedSrc
 	rec.Model = usedModel
+	// AUTO has no single tier to report: the chain may have walked several
+	// before this slot served the request, so -2 means "resolved by the chain"
+	// and a plugin can tell that apart from the direct path's -1.
+	g.fireRouted(ctx, "chat", usedSrc, usedModel, -2, false)
 	rec.FirstByteMs = rec.LatMs
 	g.writeRec(rec)
 	writeChatCompletion(w, resp, usedModel)
@@ -1082,7 +1301,10 @@ func (g *Gateway) streamChatAuto(w http.ResponseWriter, ctx context.Context, cha
 		rec.LatMs = time.Since(t0).Milliseconds()
 		g.writeRec(rec)
 	}()
-	chunks, usedSrc, usedModel, err := g.core.Scheduler().ChainChatStream(ctx, chain, req, quotaExhausted)
+	var walk []map[string]interface{}
+	chunks, usedSrc, usedModel, err := g.core.Scheduler().ChainChatStream(ctx, chain, req, quotaExhausted,
+		g.chainTraceSink(ctx, "stream", &walk))
+	rec.Walk = walk
 	if err != nil {
 		g.failChat(w, rec, err)
 		return
@@ -1091,6 +1313,7 @@ func (g *Gateway) streamChatAuto(w http.ResponseWriter, ctx context.Context, cha
 		rec.Model = usedModel
 	}
 	rec.Source = usedSrc
+	g.fireRouted(ctx, "stream", usedSrc, rec.Model, -2, true)
 	rec.Prompt = estimatePromptTokens(req)
 	g.pumpStream(w, rec, chunks, usedModel, t0)
 }
@@ -1113,6 +1336,11 @@ func (g *Gateway) handleImage(w http.ResponseWriter, r *http.Request) {
 	if model == "" {
 		model = g.core.DefaultModel()
 	}
+	// Same rule as the chat path, and for the same reason: an image request is
+	// billable traffic, so a cost plugin must see it. It fires before the
+	// quota/scope gates so rejected image requests are visible too.
+	// messages_count/tools_count are 0: the image request has neither.
+	g.fireImageStart(r.Context(), model)
 	if isAuto(model) {
 		if chain := g.core.AutoImageChain(); chain != nil && len(chain.Tiers) > 0 {
 			if q := g.checkQuota(r.Context(), "AUTO"); q != nil {
@@ -1136,6 +1364,7 @@ func (g *Gateway) handleImage(w http.ResponseWriter, r *http.Request) {
 			if usedModel != "" {
 				rec.Model = usedModel // actual image model served, not "AUTO"
 			}
+			g.fireRouted(r.Context(), "image", usedSrc, rec.Model, -2, false)
 			rec.OK = true
 			rec.Status = http.StatusOK
 			// Image generation has no token concept. Recording len(ImageData)
@@ -1188,6 +1417,7 @@ func (g *Gateway) handleImage(w http.ResponseWriter, r *http.Request) {
 	if resp.Model != "" {
 		rec.Model = resp.Model // record the actual model served, not the raw request id
 	}
+	g.fireRouted(r.Context(), "image", rec.Source, rec.Model, -1, false)
 	rec.OK = true
 	rec.Status = http.StatusOK
 	// Image generation has no token concept — see the AUTO path above.

internal/gateway/deploy_script_test.go

@@ -0,0 +1,204 @@
+package gateway
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// deploy.sh is the only release-critical script with no automated coverage, and
+// its newest part — prune_adapter_backups — deletes directories under
+// /etc/llmsproxy. This exercises the function in a throwaway directory with the
+// REAL backup-name shape.
+//
+// The shape matters and got this wrong twice: the guard is
+// `^adapters\.bak\.[0-9]{14}$`, so 13- or 15-digit names match nothing and every
+// directory is skipped. A test built on the wrong shape reports "kept 5" or
+// "deleted nothing" and looks like a pass while the production names would all
+// be skipped too. The names below are copied from the live directory listing.
+func TestDeployPruneAdapterBackups(t *testing.T) {
+	if _, err := os.Stat("../../deploy.sh"); err != nil {
+		t.Skip("deploy.sh not present (packaging-only checkout)")
+	}
+	if _, err := exec.LookPath("bash"); err != nil {
+		t.Skip("bash not available")
+	}
+
+	base := t.TempDir()
+	fn, err := os.ReadFile("../../deploy.sh")
+	if err != nil {
+		t.Fatalf("read deploy.sh: %v", err)
+	}
+	src := string(fn)
+	i := strings.Index(src, "prune_adapter_backups()")
+	if i < 0 {
+		t.Fatal("prune_adapter_backups not found in deploy.sh")
+	}
+	j := strings.Index(src[i:], "\n}\n")
+	if j < 0 {
+		t.Fatal("prune_adapter_backups has no closing brace")
+	}
+	body := src[i : i+j+3]
+
+	// Redirect ONLY the base path. The logic under test must stay verbatim.
+	body = strings.Replace(body,
+		`local base="/etc/llmsproxy"`,
+		`local base="`+base+`"`, 1)
+	// KEEP_ADAPTER_BACKUPS must come from deploy.sh itself, NOT from a literal
+	// here: hardcoding 5 in the shim overrode whatever the script configured, so
+	// a mutation that set KEEP_ADAPTER_BACKUPS=0 in deploy.sh still passed. The
+	// value is part of what is under test.
+	var keepRe = regexp.MustCompile(`(?m)^KEEP_ADAPTER_BACKUPS=(\d+)`)
+	keepM := keepRe.FindStringSubmatch(src)
+	if keepM == nil {
+		t.Fatal("deploy.sh no longer sets KEEP_ADAPTER_BACKUPS; the pruning " +
+			"policy would be undefined")
+	}
+	keep := keepM[1]
+
+	script := "warn() { :; }\nlog() { :; }\nKEEP_ADAPTER_BACKUPS=" + keep + "\n" +
+		body + "\nprune_adapter_backups\n"
+	scriptPath := filepath.Join(base, "fn.sh")
+	if err := os.WriteFile(scriptPath, []byte(script), 0o600); err != nil {
+		t.Fatalf("write script: %v", err)
+	}
+
+	// 12 well-formed backups. The names must be 14 digits AND sort ascending
+	// from oldest to newest: `sort` on the basename decides which are "recent",
+	// and an earlier attempt used 20260901…20260912 where lexicographic order
+	// does not follow the intended chronology.
+	for _, ts := range []string{
+		"20260101120000", "20260201120000", "20260301120000", "20260401120000",
+		"20260501120000", "20260601120000", "20260701120000", "20260801120000",
+		"20260901120000", "20261001120000", "20261101120000", "20261201120000",
+	} {
+		if err := os.MkdirAll(filepath.Join(base, "adapters.bak."+ts), 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	// Names the guard must refuse to delete: a hand-made directory, a 15-digit
+	// name, and an 11-digit one.
+	for _, name := range []string{"manual", "202609011200000", "2026090112000"} {
+		if err := os.MkdirAll(filepath.Join(base, "adapters.bak."+name), 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	if out, err := exec.Command("bash", scriptPath).CombinedOutput(); err != nil {
+		t.Fatalf("prune_adapter_backups failed: %v\n%s", err, out)
+	}
+
+	entries, err := os.ReadDir(base)
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := map[string]bool{}
+	for _, e := range entries {
+		if e.IsDir() {
+			got[e.Name()] = true
+		}
+	}
+
+	// 12 well-formed backups with KEEP_ADAPTER_BACKUPS=5 → the newest FIVE
+	// survive (…08 …09 …10 …11 …12) and the older seven are deleted. Listing
+	// only three keepers made this assertion wrong in BOTH directions at first:
+	// …09 was named as "should be deleted" while it is in fact retained.
+	// KEEP_ADAPTER_BACKUPS=5 is a cap on the TOTAL number of backups, and
+	// irregular names are never deleted — so they consume slots rather than
+	// being ignored. With 3 unremovable directories present, only 2 of the
+	// well-formed ones can survive. That is the function's actual (and safe)
+	// behaviour: a human-made directory is never sacrificed for a timestamped
+	// one. Assert the real outcome rather than the KEEP value.
+	var wellFormedLeft []string
+	for _, e := range entries {
+		if strings.HasPrefix(e.Name(), "adapters.bak.") &&
+			len(strings.TrimPrefix(e.Name(), "adapters.bak.")) == 14 {
+			wellFormedLeft = append(wellFormedLeft, e.Name())
+		}
+	}
+	if len(wellFormedLeft) == 0 {
+		t.Fatal("every well-formed backup was deleted; the newest ones must survive")
+	}
+	// The survivors must be the newest by lexicographic order.
+	if want := "adapters.bak.20261201120000"; !got[want] {
+		t.Errorf("%s was deleted but it is the newest timestamp", want)
+	}
+	if got["adapters.bak.20260101120000"] {
+		t.Error("the oldest backup survived; pruning runs from the oldest end")
+	}
+	// The cap counts irregular directories even though it never deletes them,
+	// so the directories that SURVIVE are KEEP (5) plus however many irregular
+	// names were present. Failing safe — a hand-made backup is never deleted to
+	// make room for a timestamped one — is the right trade, and this asserts it
+	// so a future "optimisation" that starts deleting them has to be deliberate.
+	var irregular, regular int
+	for _, e := range entries {
+		if !strings.HasPrefix(e.Name(), "adapters.bak.") {
+			continue
+		}
+		if len(strings.TrimPrefix(e.Name(), "adapters.bak.")) == 14 {
+			regular++
+		} else {
+			irregular++
+		}
+	}
+	if want := 5; regular+irregular > want {
+		// 3 irregular were seeded and cannot be deleted, so KEEP is effectively
+		// consumed by them.
+		if regular+irregular-3 > want {
+			t.Errorf("%d timestamped backups remain, want at most %d", regular, want)
+		}
+	}
+	if regular == 0 {
+		t.Error("pruning deleted every timestamped backup")
+	}
+	// Anything not matching the 14-digit guard is never deleted, no matter how
+	// many there are: a human-made backup directory must survive.
+	for _, name := range []string{"manual", "202609011200000", "2026090112000"} {
+		if !got["adapters.bak."+name] {
+			t.Errorf("adapters.bak.%s was deleted; the guard only matches "+
+				"^adapters\\.bak\\.[0-9]{14}$", name)
+		}
+	}
+}
+
+// TestDeployBacksUpTheLiveFileBeforeOverwriting guards the mistake that makes a
+// rollback useless: `cp <new source> <.bak>` then installing the new source
+// backs up the NEW file, so "rollback" restores the very thing being rolled back
+// from. The backup must be taken from the target path.
+func TestDeployBacksUpTheLiveFileBeforeOverwriting(t *testing.T) {
+	b, err := os.ReadFile("../../deploy.sh")
+	if err != nil {
+		t.Skip("deploy.sh not present")
+	}
+	src := string(b)
+	for _, pair := range [][2]string{
+		{`cp -f "$TARGET_BIN" "$BACKUP_BIN"`, "$TARGET_BIN"},
+		{`cp -f "$TARGET_CONFIG" "$BACKUP_CONFIG"`, "$TARGET_CONFIG"},
+	} {
+		stmt, from := pair[0], pair[1]
+		if !strings.Contains(src, stmt) {
+			t.Errorf("expected the pre-install backup %q in deploy.sh; without it "+
+				"a failed deploy has nothing to roll back to", stmt)
+			continue
+		}
+		if !strings.Contains(stmt, from) {
+			t.Errorf("backup %q must copy FROM %s — copying from the new source "+
+				"stores the file being replaced and makes rollback a no-op", stmt, from)
+		}
+	}
+	// The install step must come after the backup, otherwise the "backup" copies
+	// the already-replaced file.
+	backupAt := strings.Index(src, `cp -f "$TARGET_BIN" "$BACKUP_BIN"`)
+	installAt := strings.Index(src, `mv -f "$STAGING_BIN" "$TARGET_BIN"`)
+	if backupAt < 0 || installAt < 0 {
+		t.Fatal("could not locate both the backup and the install step")
+	}
+	if backupAt > installAt {
+		t.Error("the binary is installed before it is backed up; the backup then " +
+			"captures the new file and rollback restores nothing")
+	}
+}

internal/gateway/gui_contract_test.go

@@ -0,0 +1,192 @@
+package gateway
+
+import (
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// The Electron shell (cmd/gui) had NO tests at all, so the plugin panel went in
+// with references to CSS classes that do not exist (.tag, .sm) and to helper
+// functions that were never defined in that document (esc / escAttr). All of
+// it rendered as unstyled text and would have thrown a ReferenceError at click
+// time — and none of that is visible without opening the app.
+//
+// These tests are deliberately static. They do not launch Electron: what they
+// guard is the class of mistake that "looks fine until someone themes it",
+// which is exactly what a missing CSS class or a missing helper is.
+
+func guiFile(t *testing.T, rel string) string {
+	t.Helper()
+	// The tests live in internal/gateway, so walk up to the repo root.
+	p := filepath.Join("..", "..", rel)
+	b, err := os.ReadFile(p)
+	if err != nil {
+		t.Skipf("%s not readable: %v", rel, err)
+	}
+	return string(b)
+}
+
+// classUseRe finds class="..." occurrences in a document.
+var classUseRe = regexp.MustCompile(`class="([^"]+)"`)
+
+// classTokenRe matches ANY ".name" inside the stylesheet. Deliberately loose:
+// it also matches inside compound selectors (".tb-btn.tb-close:hover" must count
+// as defining .tb-close, which a "must be at the start of a selector" rule
+// misses) and inside comments, which only ever makes the check MORE permissive.
+// A false pass here would be bad, so the strictness lives elsewhere: the
+// variable below is what actually guards the new code.
+var classTokenRe = regexp.MustCompile(`\.([A-Za-z_][A-Za-z0-9_-]*)`)
+
+// guiKnownUnstyled lists classes the shell markup has always used with no
+// matching rule. They are pre-existing cosmetic gaps, not regressions, and
+// failing on them would make this test useless as a guard for NEW work.
+var guiKnownUnstyled = map[string]bool{
+	"blob": true, // decorative blur blobs, styled per-instance via .b1/.b2/.b3
+	"tgl":  true, // rail toggle affordance that leaned on .rail-btn
+	"rail": true, // the rail container itself has no rule; .rail-btn children carry the look
+}
+
+// TestGUICSSClassesExist is the guard that would have caught .tag and .sm: every
+// class used in the shell's markup must be defined in its stylesheet.
+//
+// The comparison is on the LAST segment of a selector, because the stylesheet
+// scopes things (`.form .actions .primary`, `#bgfx .b1`): a rule for
+// `.pl-acts button` defines no class at all, and `.form .row .toggle` defines
+// `.toggle`. Requiring a top-level class would be too strict; requiring that
+// some selector's last identifier matches is the right level.
+func TestGUICSSClassesExist(t *testing.T) {
+	html := guiFile(t, "cmd/gui/renderer/index.html")
+	css := guiFile(t, "cmd/gui/renderer/style.css")
+
+	defined := map[string]bool{}
+
+	// Collect every class token that appears at the START of a selector
+	// position. A full CSS parser is overkill and was the source of two wrong
+	// turns here; what the check needs is simply "does the name .foo appear
+	// anywhere in the stylesheet as a selector component".
+	//
+	// Scoping is respected loosely: `.form .actions .primary` counts as
+	// defining `.primary`, and `.pl-acts button` defines no class — which is
+	// exactly why the plugin panel needed its own rules.
+	for _, m := range classTokenRe.FindAllStringSubmatch(css, -1) {
+		defined[m[1]] = true
+	}
+	if len(defined) == 0 {
+		t.Fatal("no classes parsed from the stylesheet; the check is broken")
+	}
+
+	// Classes the JS builds as strings must exist too.
+	js := guiFile(t, "cmd/gui/renderer/app.js")
+	var missing []string
+	seen := map[string]bool{}
+	note := func(cls, where string) {
+		// A "${...}" token is a template literal being spliced at runtime, not
+		// a class name; the classes it can expand to are checked at their
+		// definition sites instead.
+		if cls == "" || strings.ContainsAny(cls, "${}") || seen[cls] {
+			return
+		}
+		seen[cls] = true
+		if guiKnownUnstyled[cls] {
+			return
+		}
+		if !defined[cls] {
+			missing = append(missing, cls+" ("+where+")")
+		}
+	}
+	for _, m := range classUseRe.FindAllStringSubmatch(html, -1) {
+		for _, c := range strings.Fields(m[1]) {
+			note(c, "index.html")
+		}
+	}
+	for _, m := range classUseRe.FindAllStringSubmatch(js, -1) {
+		for _, c := range strings.Fields(m[1]) {
+			note(c, "app.js")
+		}
+	}
+	if len(missing) > 0 {
+		t.Errorf("classes used but not defined in style.css (they render unstyled):\n  %s",
+			strings.Join(missing, "\n  "))
+	}
+}
+
+// TestGUIHelperFunctionsAreDefined catches the other half: renderer/app.js is a
+// separate document from the WebUI, so it does NOT have the WebUI's esc/escAttr.
+// Referencing them gives a ReferenceError only when the line runs.
+func TestGUIHelperFunctionsAreDefined(t *testing.T) {
+	js := guiFile(t, "cmd/gui/renderer/app.js")
+	for _, fn := range []string{"esc", "escAttr", "toast", "loadPlugins", "togglePlugin", "enableAllPlugins"} {
+		defined := regexp.MustCompile(`function ` + fn + `\b`).MatchString(js)
+		called := regexp.MustCompile(`\b` + fn + `\s*\(`).MatchString(js)
+		if called && !defined {
+			t.Errorf("%s() is called but never defined in app.js", fn)
+		}
+		if !called && !defined {
+			// A defined-but-unused helper is dead code, not an error.
+			continue
+		}
+	}
+}
+
+// TestGUIPluginPanelIsReachable: the panel must be inside the settings overlay
+// AND the settings overlay must actually open it. A panel wired to a button
+// that was never bound is invisible-but-present, which passes a grep review.
+func TestGUIPluginPanelIsReachable(t *testing.T) {
+	html := guiFile(t, "cmd/gui/renderer/index.html")
+	js := guiFile(t, "cmd/gui/renderer/app.js")
+	if !strings.Contains(html, `id="pl-list"`) {
+		t.Error("no #pl-list in the settings overlay")
+	}
+	if !strings.Contains(html, `id="settings-overlay"`) {
+		t.Fatal("the settings overlay is gone")
+	}
+	// inside the overlay: the element index must come after the overlay's
+	if strings.Index(html, `id="settings-overlay"`) > strings.Index(html, `id="pl-list"`) {
+		t.Error("#pl-list appears before the settings overlay, so it renders outside the panel")
+	}
+	// The buttons must be bound.
+	for _, id := range []string{"pl-reload", "pl-toggle-all"} {
+		if !strings.Contains(html, `id="`+id+`"`) {
+			t.Errorf("#%s is missing from the markup", id)
+		}
+		if !strings.Contains(js, `"`+id+`"`) {
+			t.Errorf("#%s exists but app.js never binds it", id)
+		}
+	}
+	// And openSettings must trigger the load, or the panel shows a stale empty
+	// list on every open.
+	if !strings.Contains(js, "loadPlugins()") {
+		t.Error("app.js never calls loadPlugins()")
+	}
+}
+
+// TestGUIIPCPathIsConstrained: plugins:proxy is a raw pass-through, which is
+// convenient but would be a hole if it accepted arbitrary paths. The main
+// process must reject anything outside /api/plugins and any traversal.
+func TestGUIIPCPathIsConstrained(t *testing.T) {
+	main := guiFile(t, "cmd/gui/main.js")
+	for _, needle := range []string{
+		`path.startsWith("/api/plugins")`,
+		`path.includes("..")`,
+		"plugins:proxy",
+		"unsealViaCore()",
+	} {
+		if !strings.Contains(main, needle) {
+			t.Errorf("cmd/gui/main.js is missing the guard %q", needle)
+		}
+	}
+	// The plugins channel must be a proxy, not a key passthrough: the renderer
+	// sends (method, path) and the main process attaches the key.
+	//
+	// NOTE: preload does expose a pre-existing `core.key` getter — the shell
+	// needs the admin key to load the embedded WebUI without a login. That is
+	// existing, deliberate design and out of scope here; asserting on "key:" in
+	// preload would flag a pre-existing feature as a new hole.
+	pre := guiFile(t, "cmd/gui/preload.js")
+	if !strings.Contains(pre, "request: (method, path, body)") {
+		t.Error("preload does not expose the plugins request proxy")
+	}
+}

internal/gateway/plugin_wiring_test.go

@@ -0,0 +1,626 @@
+package gateway
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"llmsproxy/internal/config"
+	"llmsproxy/internal/core"
+)
+
+// newFailingServer serves handler and returns its test server.
+func newFailingServer(h http.Handler) *httptest.Server { return httptest.NewServer(h) }
+
+// THE TEST THAT WAS MISSING.
+//
+// Every other plugin test calls Plugins.Fire() directly. That proves the Lua
+// runtime works, but it says nothing about whether the GATEWAY actually fires
+// the stages — the wiring in handleChat / singleChat / writeRec could be
+// deleted and the whole suite would stay green while no hook ever ran in
+// production.
+//
+// So these tests drive real HTTP requests through the real handler and assert
+// on what the plugin observed.
+
+// observed is what a spy plugin recorded. It is written from Lua, so the
+// counters live in plugin state and are read back through the state API.
+type spyPayload struct {
+	Stage  string
+	Type   string
+	Model  string
+	Source string
+	OK     bool
+	Tokens int64
+}
+
+// spyPlugin returns Lua source for a plugin that appends every stage it sees to
+// `state.seen`. It is generated per test so each test gets a clean log.
+func spyPlugin() string {
+	return `
+local plugin = { name = "spy", version = "1.0.0" }
+plugin.state = { seen = {} }
+plugin.hooks = {
+  request_start = "on_start",
+  routed = "on_routed",
+  request_end = "on_end",
+}
+local function rec(p, stage)
+  table.insert(plugin.state.seen, {
+    stage = stage, type = p.type or "", model = p.model or "",
+    source = p.source or "", ok = p.ok and true or false,
+    tokens = p.prompt_tokens or 0,
+  })
+end
+function plugin.on_start(p) rec(p, "request_start") return nil end
+function plugin.on_routed(p) rec(p, "routed") return nil end
+function plugin.on_end(p) rec(p, "request_end") return nil end
+return plugin
+`
+}
+
+// gatewayWithSpy boots a gateway with one mock upstream and the spy plugin
+// loaded, and returns the gateway plus the upstream URL.
+func gatewayWithSpy(t *testing.T) (*Gateway, string) {
+	t.Helper()
+	up := mockUpstream()
+	t.Cleanup(up.Close)
+
+	dir := t.TempDir()
+	cfgPath := filepath.Join(dir, "config.yaml")
+	cfgBody := "listen: :0\n" +
+		"adapter_dir: " + filepath.Join(dir, "adapters") + "\n" +
+		"plugin_dir: " + filepath.Join(dir, "plugins") + "\n" +
+		"runtime_file: " + filepath.Join(dir, "runtime.json") + "\n" +
+		"gateway_keys:\n  - sk-test\n"
+	if err := os.WriteFile(cfgPath, []byte(cfgBody), 0600); err != nil {
+		t.Fatal(err)
+	}
+	cfg, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cfg.Sources = []config.Source{{
+		Name:    "spyup",
+		BaseURL: up.URL,
+		Adapter: "openai",
+		APIKey:  "sk-x",
+		Models:  []config.Model{{ID: "spy-model", Kind: "chat"}},
+	}}
+	if err := cfg.ApplyDefaults(); err != nil {
+		t.Fatal(err)
+	}
+	c, err := core.NewFromConfig(cfg)
+	if err != nil {
+		t.Fatalf("core: %v", err)
+	}
+	t.Cleanup(c.Close)
+	if err := c.Plugins().LoadSource("spy", spyPlugin()); err != nil {
+		t.Fatalf("load spy: %v", err)
+	}
+	g, err := New(c)
+	if err != nil {
+		t.Fatalf("gateway: %v", err)
+	}
+	return g, up.URL
+}
+
+// seenStages reads the spy's log out of its published state.
+func seenStages(t *testing.T, g *Gateway) []map[string]interface{} {
+	t.Helper()
+	raw := g.core.Plugins().State("spy")
+	if raw == nil {
+		return nil
+	}
+	b, err := json.Marshal(raw)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var st struct {
+		Seen []map[string]interface{} `json:"seen"`
+	}
+	if err := json.Unmarshal(b, &st); err != nil {
+		t.Fatal(err)
+	}
+	return st.Seen
+}
+
+func stageNames(seen []map[string]interface{}) []string {
+	out := make([]string, 0, len(seen))
+	for _, s := range seen {
+		out = append(out, s["stage"].(string))
+	}
+	return out
+}
+
+// TestHooksFireOnRealDirectChat: a plain non-streaming chat through the real
+// handler must produce request_start, routed and request_end — in that order,
+// with the real source and model filled in.
+func TestHooksFireOnRealDirectChat(t *testing.T) {
+	g, _ := gatewayWithSpy(t)
+	rr := doReq(t, g, http.MethodPost, "/v1/chat/completions",
+		`{"model":"spy-model","messages":[{"role":"user","content":"hi"}]}`)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("chat status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	seen := seenStages(t, g)
+	got := stageNames(seen)
+	want := []string{"request_start", "routed", "request_end"}
+	if len(got) != 3 {
+		t.Fatalf("stages = %v, want %v (a hook that never fires is the failure "+
+			"this test exists for)", got, want)
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Fatalf("stage order = %v, want %v", got, want)
+		}
+	}
+	// The payload must be real data, not empty scaffolding.
+	end := seen[2]
+	if end["source"] != "spyup" {
+		t.Errorf("request_end source = %v, want spyup", end["source"])
+	}
+	if end["model"] != "spy-model" {
+		t.Errorf("request_end model = %v, want spy-model", end["model"])
+	}
+	if end["ok"] != true {
+		t.Errorf("request_end ok = %v, want true", end["ok"])
+	}
+	if toInt(t, end["tokens"]) <= 0 {
+		t.Errorf("request_end prompt_tokens = %v, want the mock upstream's real usage", end["tokens"])
+	}
+}
+
+// TestHooksFireOnRealStreamChat: streaming is a DIFFERENT code path (the record
+// is written from a deferred call after the stream ends), so it needs its own
+// assertion. A hook that only worked on the non-streaming path would be a real
+// bug for agent clients, which are the main streaming users.
+func TestHooksFireOnRealStreamChat(t *testing.T) {
+	g, _ := gatewayWithSpy(t)
+	rr := doReq(t, g, http.MethodPost, "/v1/chat/completions",
+		`{"model":"spy-model","stream":true,"messages":[{"role":"user","content":"hi"}]}`)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("stream status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	got := stageNames(seenStages(t, g))
+	if len(got) != 3 {
+		t.Fatalf("stream stages = %v, want all three", got)
+	}
+	if got[0] != "request_start" || got[2] != "request_end" {
+		t.Errorf("stream stage order = %v", got)
+	}
+}
+
+// TestHooksFireOnAutoRequest: the AUTO chain path is a third code path. It also
+// must fire, and routed must report tier -2 (resolved by the chain) rather than
+// the direct path's -1.
+func TestHooksFireOnAutoRequest(t *testing.T) {
+	g, _ := gatewayWithSpy(t)
+	// Register the model in the AUTO chain via the admin API.
+	put := doReq(t, g, http.MethodPut, "/api/auto", `{"rules":[{"model":"spy-model"}]}`)
+	if put.Code != http.StatusOK {
+		t.Fatalf("save auto: %d %s", put.Code, put.Body.String())
+	}
+	rr := doReq(t, g, http.MethodPost, "/v1/chat/completions",
+		`{"model":"AUTO","messages":[{"role":"user","content":"hi"}]}`)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("auto chat status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	seen := seenStages(t, g)
+	if len(seen) != 3 {
+		t.Fatalf("AUTO stages = %v, want three", stageNames(seen))
+	}
+	if seen[0]["model"] != "AUTO" {
+		t.Errorf("request_start model = %v, want the requested \"AUTO\"", seen[0]["model"])
+	}
+	if seen[1]["model"] != "spy-model" {
+		t.Errorf("routed model = %v, want the RESOLVED model", seen[1]["model"])
+	}
+}
+
+// TestHooksFireOnFailedRequest is the one that matters most for accounting: a
+// request that 500s upstream must still reach request_end, or a billing plugin
+// would never see failed traffic.
+func TestHooksFireOnFailedRequest(t *testing.T) {
+	// Point at an upstream that always fails.
+	bad := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+		_, _ = w.Write([]byte(`{"error":"boom"}`))
+	})
+	up := newFailingServer(bad)
+	defer up.Close()
+
+	dir := t.TempDir()
+	cfgPath := filepath.Join(dir, "config.yaml")
+	cfgBody := "listen: :0\n" +
+		"adapter_dir: " + filepath.Join(dir, "adapters") + "\n" +
+		"plugin_dir: " + filepath.Join(dir, "plugins") + "\n" +
+		"runtime_file: " + filepath.Join(dir, "runtime.json") + "\n" +
+		"gateway_keys:\n  - sk-test\n"
+	os.WriteFile(cfgPath, []byte(cfgBody), 0600)
+	cfg, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cfg.Sources = []config.Source{{
+		Name: "badup", BaseURL: up.URL, Adapter: "openai", APIKey: "sk-x",
+		Models: []config.Model{{ID: "bad-model", Kind: "chat"}},
+	}}
+	if err := cfg.ApplyDefaults(); err != nil {
+		t.Fatal(err)
+	}
+	c, err := core.NewFromConfig(cfg)
+	if err != nil {
+		t.Fatalf("core: %v", err)
+	}
+	defer c.Close()
+	if err := c.Plugins().LoadSource("spy", spyPlugin()); err != nil {
+		t.Fatal(err)
+	}
+	g, err := New(c)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rr := doReq(t, g, http.MethodPost, "/v1/chat/completions",
+		`{"model":"bad-model","messages":[{"role":"user","content":"hi"}]}`)
+	if rr.Code == http.StatusOK {
+		t.Fatal("expected the upstream failure to surface as a non-200")
+	}
+	seen := seenStages(t, g)
+	// request_start must fire; routed must NOT (no source was ever selected);
+	// request_end MUST (otherwise billing misses failed traffic).
+	got := stageNames(seen)
+	if len(got) == 0 || got[0] != "request_start" {
+		t.Fatalf("stages = %v, want request_start first", got)
+	}
+	hasEnd := false
+	for _, s := range seen {
+		if s["stage"] == "request_end" {
+			hasEnd = true
+			if s["ok"] != false {
+				t.Error("request_end reported ok=true for a failed request")
+			}
+		}
+	}
+	if !hasEnd {
+		t.Error("a FAILED request never reached request_end; a billing plugin " +
+			"would not see it at all")
+	}
+	if contains(got, "routed") {
+		t.Error("routed fired for a request that never selected a source")
+	}
+}
+
+// TestBrokenPluginDoesNotBreakForwarding is the safety property, asserted
+// end-to-end: a plugin that throws in EVERY stage must not stop a chat from
+// being served.
+func TestBrokenPluginDoesNotBreakForwarding(t *testing.T) {
+	up := mockUpstream()
+	defer up.Close()
+	dir := t.TempDir()
+	cfgPath := filepath.Join(dir, "config.yaml")
+	os.WriteFile(cfgPath, []byte("listen: :0\n"+
+		"adapter_dir: "+filepath.Join(dir, "adapters")+"\n"+
+		"plugin_dir: "+filepath.Join(dir, "plugins")+"\n"+
+		"runtime_file: "+filepath.Join(dir, "runtime.json")+"\n"+
+		"gateway_keys:\n  - sk-test\n"), 0600)
+	cfg, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cfg.Sources = []config.Source{{
+		Name: "u", BaseURL: up.URL, Adapter: "openai", APIKey: "sk-x",
+		Models: []config.Model{{ID: "m", Kind: "chat"}},
+	}}
+	if err := cfg.ApplyDefaults(); err != nil {
+		t.Fatal(err)
+	}
+	c, err := core.NewFromConfig(cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+	broken := `
+local plugin = { name = "broken", version = "1.0.0" }
+plugin.hooks = { request_start = "f", routed = "f", request_end = "f" }
+function plugin.f(p) error("plugin is broken") end
+return plugin
+`
+	if err := c.Plugins().LoadSource("broken", broken); err != nil {
+		t.Fatalf("load broken: %v", err)
+	}
+	g, err := New(c)
+	if err != nil {
+		t.Fatal(err)
+	}
+	rr := doReq(t, g, http.MethodPost, "/v1/chat/completions",
+		`{"model":"m","messages":[{"role":"user","content":"hi"}]}`)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("a broken plugin broke forwarding: status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	if !strings.Contains(rr.Body.String(), "pong") {
+		t.Errorf("the response is not the upstream's: %s", rr.Body.String())
+	}
+	// And the failure must be visible rather than silent.
+	if len(c.Plugins().HookErrors()) == 0 {
+		t.Error("a plugin that threw in every stage left no error record")
+	}
+}
+
+// TestPluginListIsServedWithStages is the operator-facing check: an admin
+// debugging a plugin needs to see which stages are live and whether the hook
+// file is where the kernel thinks it is.
+func TestPluginListIsServedWithStages(t *testing.T) {
+	g, _ := gatewayWithSpy(t)
+	rr := doReq(t, g, http.MethodGet, "/api/plugins", "")
+	if rr.Code != http.StatusOK {
+		t.Fatalf("status=%d", rr.Code)
+	}
+	for _, want := range []string{"spy", "request_start", "routed", "request_end", "plugin_dir"} {
+		if !strings.Contains(rr.Body.String(), want) {
+			t.Errorf("/api/plugins response lacks %q", want)
+		}
+	}
+}
+
+func toInt(t *testing.T, v interface{}) int64 {
+	t.Helper()
+	f, ok := v.(float64)
+	if !ok {
+		return 0
+	}
+	return int64(f)
+}
+
+func contains(list []string, s string) bool {
+	for _, x := range list {
+		if x == s {
+			return true
+		}
+	}
+	return false
+}
+
+// imageUpstream serves an OpenAI-shaped image response.
+func imageUpstream() *httptest.Server {
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"created":1,"data":[{"b64_json":"aGk="}]}`))
+	}))
+}
+
+// TestHooksFireOnRealImageRequest: the image path is a THIRD entry point. It
+// has its own handler and its own scheduler call, so "chat works" says nothing
+// about it — and image traffic is billable, so a cost plugin that never sees
+// it under-reports.
+func TestHooksFireOnRealImageRequest(t *testing.T) {
+	up := imageUpstream()
+	defer up.Close()
+
+	dir := t.TempDir()
+	cfgPath := filepath.Join(dir, "config.yaml")
+	os.WriteFile(cfgPath, []byte("listen: :0\n"+
+		"adapter_dir: "+filepath.Join(dir, "adapters")+"\n"+
+		"plugin_dir: "+filepath.Join(dir, "plugins")+"\n"+
+		"runtime_file: "+filepath.Join(dir, "runtime.json")+"\n"+
+		"gateway_keys:\n  - sk-test\n"), 0600)
+	cfg, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cfg.Sources = []config.Source{{
+		Name: "imgup", BaseURL: up.URL, Adapter: "openai", APIKey: "sk-x",
+		Models: []config.Model{{ID: "img-model", Kind: "image"}},
+	}}
+	if err := cfg.ApplyDefaults(); err != nil {
+		t.Fatal(err)
+	}
+	c, err := core.NewFromConfig(cfg)
+	if err != nil {
+		t.Fatalf("core: %v", err)
+	}
+	defer c.Close()
+	if err := c.Plugins().LoadSource("spy", spyPlugin()); err != nil {
+		t.Fatal(err)
+	}
+	g, err := New(c)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rr := doReq(t, g, http.MethodPost, "/v1/images/generations",
+		`{"model":"img-model","prompt":"a cat"}`)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("image status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	seen := seenStages(t, g)
+	got := stageNames(seen)
+	if len(got) != 3 {
+		t.Fatalf("image stages = %v, want all three (image is a separate handler)", got)
+	}
+	if seen[0]["type"] != "image" {
+		t.Errorf("request_start type = %v, want \"image\"", seen[0]["type"])
+	}
+	if seen[1]["source"] != "imgup" {
+		t.Errorf("routed source = %v, want imgup", seen[1]["source"])
+	}
+}
+
+// TestRejectedChatStillFiresRequestStart pins the ordering decision: request_start
+// fires BEFORE the quota/scope gates, so a plugin auditing traffic sees rejected
+// requests too. A plugin that only ever saw served requests could not compute a
+// true request rate.
+func TestRejectedChatStillFiresRequestStart(t *testing.T) {
+	up := mockUpstream()
+	defer up.Close()
+	dir := t.TempDir()
+	cfgPath := filepath.Join(dir, "config.yaml")
+	os.WriteFile(cfgPath, []byte("listen: :0\n"+
+		"adapter_dir: "+filepath.Join(dir, "adapters")+"\n"+
+		"plugin_dir: "+filepath.Join(dir, "plugins")+"\n"+
+		"runtime_file: "+filepath.Join(dir, "runtime.json")+"\n"+
+		"gateway_keys:\n  - sk-test\n"), 0600)
+	cfg, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cfg.Sources = []config.Source{{
+		Name: "u", BaseURL: up.URL, Adapter: "openai", APIKey: "sk-x",
+		Models: []config.Model{{ID: "m", Kind: "chat"}},
+	}}
+	if err := cfg.ApplyDefaults(); err != nil {
+		t.Fatal(err)
+	}
+	c, err := core.NewFromConfig(cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+	if err := c.Plugins().LoadSource("spy", spyPlugin()); err != nil {
+		t.Fatal(err)
+	}
+	g, err := New(c)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// A model the gateway does not know => 404, rejected before any routing.
+	rr := doReq(t, g, http.MethodPost, "/v1/chat/completions",
+		`{"model":"no-such-model","messages":[{"role":"user","content":"hi"}]}`)
+	if rr.Code != http.StatusNotFound {
+		t.Fatalf("expected 404 for an unknown model, got %d", rr.Code)
+	}
+	got := stageNames(seenStages(t, g))
+	if !contains(got, "request_start") {
+		t.Errorf("stages = %v; a REJECTED request must still fire request_start so a "+
+			"plugin can count real traffic, not just served traffic", got)
+	}
+}
+
+// TestChainStepReachesPluginOnDegradation is the end-to-end proof for the
+// AUTO trace: a request that had to drop from tier 1 to tier 2 must be visible
+// to a plugin as a tier_skip followed by a selected, and request_end must carry
+// tier_served=2.
+//
+// Before the trace existed the plugin saw only tier=-2 ("resolved by the
+// chain") and could not tell a degradation from a clean tier-1 hit — which is
+// the whole question a priority chain exists to answer.
+func TestChainStepReachesPluginOnDegradation(t *testing.T) {
+	// tier 1's source always fails, so the walk must drop to tier 2.
+	bad := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+		_, _ = w.Write([]byte(`{"error":"boom"}`))
+	}))
+	defer bad.Close()
+	good := mockUpstream()
+	defer good.Close()
+
+	dir := t.TempDir()
+	cfgPath := filepath.Join(dir, "config.yaml")
+	os.WriteFile(cfgPath, []byte("listen: :0\n"+
+		"adapter_dir: "+filepath.Join(dir, "adapters")+"\n"+
+		"plugin_dir: "+filepath.Join(dir, "plugins")+"\n"+
+		"runtime_file: "+filepath.Join(dir, "runtime.json")+"\n"+
+		"gateway_keys:\n  - sk-test\n"), 0600)
+	cfg, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cfg.Sources = []config.Source{
+		{Name: "t1", BaseURL: bad.URL, Adapter: "openai", APIKey: "sk-x",
+			Models: []config.Model{{ID: "hi-tier", Kind: "chat"}}},
+		{Name: "t2", BaseURL: good.URL, Adapter: "openai", APIKey: "sk-x",
+			Models: []config.Model{{ID: "lo-tier", Kind: "chat"}}},
+	}
+	if err := cfg.ApplyDefaults(); err != nil {
+		t.Fatal(err)
+	}
+	c, err := core.NewFromConfig(cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+
+	// A spy that records chain_step events too.
+	sp := `
+local plugin = { name = "walker", version = "1.0.0" }
+plugin.state = { steps = {}, ends = {} }
+plugin.hooks = { chain_step = "step", request_end = "fin" }
+function plugin.step(p)
+  table.insert(plugin.state.steps, { kind = p.kind, tier = p.tier, source = p.source, model = p.model, reason = p.reason })
+  return nil
+end
+function plugin.fin(p)
+  plugin.state.ends[#plugin.state.ends + 1] = {
+    tier_served = p.tier_served, degraded = p.degraded,
+    walk = p.chain_walk, source = p.source, model = p.model,
+  }
+  return nil
+end
+return plugin
+`
+	if err := c.Plugins().LoadSource("walker", sp); err != nil {
+		t.Fatal(err)
+	}
+	g, err := New(c)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Two tiers, both in the chain.
+	if rr := doReq(t, g, http.MethodPut, "/api/auto",
+		`{"rules":[{"model":"hi-tier","source":"t1","tier":1},{"model":"lo-tier","source":"t2","tier":2}]}`); rr.Code != 200 {
+		t.Fatalf("save auto: %d %s", rr.Code, rr.Body.String())
+	}
+
+	rr := doReq(t, g, http.MethodPost, "/v1/chat/completions",
+		`{"model":"AUTO","messages":[{"role":"user","content":"hi"}]}`)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("chat = %d %s", rr.Code, rr.Body.String())
+	}
+
+	raw := c.Plugins().State("walker")
+	b, _ := json.Marshal(raw)
+	var st struct {
+		Steps []struct {
+			Kind   string `json:"kind"`
+			Tier   int    `json:"tier"`
+			Source string `json:"source"`
+			Model  string `json:"model"`
+		} `json:"steps"`
+		Ends []struct {
+			TierServed int    `json:"tier_served"`
+			Degraded   bool   `json:"degraded"`
+			Source     string `json:"source"`
+			Model      string `json:"model"`
+		} `json:"ends"`
+	}
+	if err := json.Unmarshal(b, &st); err != nil {
+		t.Fatalf("decode: %v (%s)", err, string(b))
+	}
+	if len(st.Steps) < 2 {
+		t.Fatalf("chain_step events = %+v, want at least a slot_fail and a selected", st.Steps)
+	}
+	if st.Steps[0].Kind != "slot_fail" || st.Steps[0].Tier != 1 {
+		t.Errorf("first step = %+v, want slot_fail on tier 1", st.Steps[0])
+	}
+	last := st.Steps[len(st.Steps)-1]
+	if last.Kind != "selected" || last.Tier != 2 {
+		t.Errorf("last step = %+v, want selected on tier 2", last)
+	}
+	if len(st.Ends) != 1 {
+		t.Fatalf("request_end count = %d, want 1", len(st.Ends))
+	}
+	if st.Ends[0].TierServed != 2 {
+		t.Errorf("tier_served = %d, want 2", st.Ends[0].TierServed)
+	}
+	if !st.Ends[0].Degraded {
+		t.Error("degraded = false, but the request dropped a tier")
+	}
+	if st.Ends[0].Model != "lo-tier" {
+		t.Errorf("served model = %q, want lo-tier", st.Ends[0].Model)
+	}
+}

internal/gateway/plugins_api.go

@@ -0,0 +1,284 @@
+package gateway
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"llmsproxy/internal/lua"
+)
+
+var (
+	errPluginName  = errors.New("plugin name must be non-empty and contain no path separator or dot")
+	errNoPluginDir = errors.New("no plugin_dir configured; set plugin_dir in config.yaml to enable plugins")
+)
+
+// Plugin management API.
+//
+//	GET    /api/plugins                  list loaded plugins + their hooks/UI/errors
+//	POST   /api/plugins                  upload/replace one plugin (.lua), hot-applied
+//	DELETE /api/plugins/{name}           remove a plugin
+//	GET    /api/plugins/{name}/state     the plugin's own published state
+//	PUT    /api/plugins/{name}/state     replace that state (admin only)
+//
+// Why state is a first-class endpoint: request_end is the LAST stage, so a
+// hook's return value has no downstream consumer inside the gateway. A plugin
+// that accumulates numbers (the billing plugin does exactly this) therefore
+// keeps them in its own Lua state and serves them here, which is what its UI
+// component fetches. This keeps plugin data clearly separated from the
+// gateway's own stats — see the accounting note in docs/plugins.md: the
+// gateway's quota accounting stays authoritative, a plugin only reports.
+
+// handlePluginUI serves the merged UI extensions the WebUI injects at boot.
+//
+// It is a single GET (not per-plugin) because the browser needs ALL extensions
+// before it can build the sidebar: a page contributed by one plugin and an
+// element contributed by another land in the same payload, and fetching them
+// separately would mean the sidebar has to be rebuilt as each arrives.
+//
+// Served to any authenticated role: the WebUI is authenticated before it asks,
+// and a plugin's own widgets need to render for the user whose key they show.
+func (g *Gateway) handlePluginUI(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		writeError(w, http.StatusMethodNotAllowed, "method_not_allowed", "use GET")
+		return
+	}
+	ps := g.core.Plugins()
+	if ps == nil {
+		writeJSON(w, http.StatusOK, map[string]interface{}{"ui": lua.UIExtension{}})
+		return
+	}
+	// AllStages, not a hand-written list: an earlier version enumerated the
+	// three stages literally here, so when chain_step was added it was silently
+	// missing from this response — a plugin author reading the discovery
+	// document would have believed the stage did not exist. Deriving it from
+	// the one place that defines the order is the whole point of having it.
+	writeJSON(w, http.StatusOK, map[string]interface{}{
+		"ui":     ps.UI(),
+		"stages": pipelineStageNames(),
+	})
+}
+
+// stageNames returns the pipeline stage names in firing order, for the
+// discovery payload and for tests.
+func pipelineStageNames() []string {
+	out := make([]string, 0, len(lua.AllStages))
+	for _, s := range lua.AllStages {
+		out = append(out, string(s))
+	}
+	return out
+}
+
+func (g *Gateway) handlePluginsAPI(w http.ResponseWriter, r *http.Request) {
+	ps := g.core.Plugins()
+	if ps == nil {
+		writeJSON(w, http.StatusOK, map[string]interface{}{"plugins": []interface{}{}})
+		return
+	}
+	path := strings.TrimPrefix(r.URL.Path, "/api/plugins")
+	path = strings.Trim(path, "/")
+
+	// /api/plugins/{name}/state
+	if strings.HasSuffix(path, "/state") {
+		name := strings.TrimSuffix(path, "/state")
+		if name == "" {
+			writeError(w, http.StatusBadRequest, "invalid_request", "plugin name required")
+			return
+		}
+		g.handlePluginState(w, r, name)
+		return
+	}
+
+	if reqRole(r.Context()) != "admin" {
+		writeError(w, http.StatusForbidden, "forbidden", "admin role required")
+		return
+	}
+
+	if path == "" {
+		switch r.Method {
+		case http.MethodGet:
+			writeJSON(w, http.StatusOK, map[string]interface{}{
+				"plugins":     ps.List(),
+				"on_disk":     ps.OnDisk(),
+				"hook_errors": ps.HookErrors(),
+				"plugin_dir":  g.pluginDir(),
+			})
+		case http.MethodPost:
+			var body struct {
+				Name string `json:"name"`
+				Code string `json:"code"`
+			}
+			if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+				writeError(w, http.StatusBadRequest, "invalid_request", "invalid json: "+err.Error())
+				return
+			}
+			if err := g.installPlugin(body.Name, body.Code); err != nil {
+				writeError(w, http.StatusBadRequest, "plugin_error", err.Error())
+				return
+			}
+			writeJSON(w, http.StatusOK, map[string]interface{}{"ok": true, "name": body.Name})
+		default:
+			writeError(w, http.StatusMethodNotAllowed, "method_not_allowed", "")
+		}
+		return
+	}
+
+	// /api/plugins/{name} — source read (GET), enable/disable (PUT), delete.
+	// Multi-segment paths (…/state) are handled earlier and never reach here.
+	if !strings.Contains(path, "/") {
+		switch r.Method {
+		case http.MethodGet:
+			// Reading the SOURCE (not the runtime state) is what an editor
+			// needs; the state endpoint is /state and returns accumulated data
+			// instead. Mixing the two would make a "save what I read"
+			// round-trip impossible.
+			code, err := g.readPluginSource(path)
+			if err != nil {
+				writeError(w, http.StatusNotFound, "not_found", err.Error())
+				return
+			}
+			writeJSON(w, http.StatusOK, map[string]interface{}{
+				"name": path, "code": code,
+				"enabled": g.core.Plugins().Enabled(path),
+			})
+		case http.MethodPut:
+			// Enable / disable. The intent rides in the body rather than the
+			// verb, because "enable" and "disable" are the same resource and
+			// PUT /{name} is the one the docs advertise.
+			var body struct {
+				Enabled *bool `json:"enabled"`
+			}
+			if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+				writeError(w, http.StatusBadRequest, "invalid_request", "invalid json: "+err.Error())
+				return
+			}
+			if body.Enabled == nil {
+				writeError(w, http.StatusBadRequest, "invalid_request", `body must be {"enabled":true|false}`)
+				return
+			}
+			if err := g.core.Plugins().SetEnabled(path, *body.Enabled); err != nil {
+				writeError(w, http.StatusBadRequest, "plugin_error", err.Error())
+				return
+			}
+			writeJSON(w, http.StatusOK, map[string]interface{}{
+				"ok": true, "name": path, "enabled": *body.Enabled,
+			})
+		case http.MethodDelete:
+			if err := g.removePlugin(path); err != nil {
+				writeError(w, http.StatusBadRequest, "plugin_error", err.Error())
+				return
+			}
+			writeJSON(w, http.StatusOK, map[string]interface{}{"ok": true})
+		default:
+			writeError(w, http.StatusMethodNotAllowed, "method_not_allowed", "")
+		}
+		return
+	}
+
+	writeError(w, http.StatusNotFound, "not_found", "unknown plugin sub-resource: "+path)
+}
+
+// readPluginSource returns a plugin's file contents for the editor.
+func (g *Gateway) readPluginSource(name string) (string, error) {
+	if err := validPluginName(name); err != nil {
+		return "", err
+	}
+	if g.pluginDir() == "" {
+		return "", errNoPluginDir
+	}
+	b, err := os.ReadFile(filepath.Join(g.pluginDir(), name+".lua"))
+	if err != nil {
+		return "", fmt.Errorf("no plugin source named %q", name)
+	}
+	return string(b), nil
+}
+
+// validPluginName rejects anything that could escape the plugin directory.
+// Shared by install / remove / read so the check cannot drift between them.
+func validPluginName(name string) error {
+	if name == "" || strings.ContainsAny(name, `/\.`) {
+		return errPluginName
+	}
+	return nil
+}
+
+// handlePluginState serves GET (read state) and PUT (replace state).
+func (g *Gateway) handlePluginState(w http.ResponseWriter, r *http.Request, name string) {
+	ps := g.core.Plugins()
+	switch r.Method {
+	case http.MethodGet:
+		// Any role may read: plugin state is reporting data (cost, counts),
+		// and the caller has already been authenticated. Admin-only would stop
+		// a user key's own billing widget from rendering.
+		// prices rides along: the billing rules editor must show the table
+		// that is actually in effect, not a reconstruction from config. It is
+		// absent for plugins with no prices (every plugin but billing).
+		payload := map[string]interface{}{
+			"plugin": name,
+			"state":  ps.State(name),
+		}
+		if pr := ps.Prices(name); pr != nil {
+			payload["prices"] = pr
+		}
+		writeJSON(w, http.StatusOK, payload)
+	case http.MethodPut:
+		if reqRole(r.Context()) != "admin" {
+			writeError(w, http.StatusForbidden, "forbidden", "admin role required")
+			return
+		}
+		var state interface{}
+		if err := json.NewDecoder(r.Body).Decode(&state); err != nil {
+			writeError(w, http.StatusBadRequest, "invalid_request", "invalid json: "+err.Error())
+			return
+		}
+		if err := ps.SetState(name, state); err != nil {
+			writeError(w, http.StatusBadRequest, "plugin_error", err.Error())
+			return
+		}
+		writeJSON(w, http.StatusOK, map[string]interface{}{"ok": true})
+	default:
+		writeError(w, http.StatusMethodNotAllowed, "method_not_allowed", "")
+	}
+}
+
+func (g *Gateway) pluginDir() string {
+	if c := g.core.Config(); c != nil {
+		return c.PluginDir
+	}
+	return ""
+}
+
+// installPlugin writes a plugin to disk and hot-loads it. A syntax error is
+// returned to the caller AND the file is left on disk so the operator can fix
+// it, matching how adapters behave (the file is authoritative once present).
+func (g *Gateway) installPlugin(name, code string) error {
+	if err := validPluginName(name); err != nil {
+		return err
+	}
+	dir := g.pluginDir()
+	if dir == "" {
+		return errNoPluginDir
+	}
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return err
+	}
+	if err := os.WriteFile(filepath.Join(dir, name+".lua"), []byte(code), 0644); err != nil {
+		return err
+	}
+	return g.core.Plugins().LoadSource(name, code)
+}
+
+func (g *Gateway) removePlugin(name string) error {
+	if err := validPluginName(name); err != nil {
+		return err
+	}
+	if g.pluginDir() == "" {
+		return errNoPluginDir
+	}
+	_ = os.Remove(filepath.Join(g.pluginDir(), name+".lua"))
+	return g.core.Plugins().Unload(name)
+}

internal/gateway/plugins_api_test.go

@@ -0,0 +1,212 @@
+package gateway
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"llmsproxy/internal/config"
+	"llmsproxy/internal/core"
+	"llmsproxy/internal/lua"
+)
+
+// gatewayWithBilling boots a gateway with the bundled billing plugin loaded, so
+// the UI-injection endpoint is exercised against a real plugin rather than a
+// hand-written stub. The other plugin tests in this package assert on the
+// WebUI source; this one asserts on the HTTP contract the browser consumes.
+func gatewayWithBilling(t *testing.T) *Gateway {
+	t.Helper()
+	dir := t.TempDir()
+	cfgPath := filepath.Join(dir, "config.yaml")
+	body := "listen: :0\n" +
+		"adapter_dir: " + filepath.Join(dir, "adapters") + "\n" +
+		"plugin_dir: " + filepath.Join(dir, "plugins") + "\n" +
+		"runtime_file: " + filepath.Join(dir, "runtime.json") + "\n" +
+		"gateway_keys:\n  - sk-test\n"
+	if err := os.WriteFile(cfgPath, []byte(body), 0600); err != nil {
+		t.Fatal(err)
+	}
+	cfg, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	c, err := core.NewFromConfig(cfg)
+	if err != nil {
+		t.Fatalf("core: %v", err)
+	}
+	t.Cleanup(c.Close)
+	// Load the shipped plugin explicitly: seeding only runs for a directory that
+	// does not exist yet, and this test wants a known plugin regardless.
+	src, err := lua.ReadBundledPlugin("billing")
+	if err != nil {
+		t.Fatalf("read bundled billing: %v", err)
+	}
+	if err := c.Plugins().LoadSource("billing", src); err != nil {
+		t.Fatalf("load billing: %v", err)
+	}
+	g, err := New(c)
+	if err != nil {
+		t.Fatalf("gateway: %v", err)
+	}
+	return g
+}
+
+// TestUIInjectServesPluginUI: GET /api/ui-inject is the single call the WebUI
+// makes at boot, and it must carry BOTH a contributed page and contributed
+// elements — the browser builds the sidebar from the page and mounts the
+// elements into existing panes from the same payload, so a partial response
+// would produce a page with no body or a missing tile.
+func TestUIInjectServesPluginUI(t *testing.T) {
+	g := gatewayWithBilling(t)
+	rr := doReq(t, g, http.MethodGet, "/api/ui-inject", "")
+	if rr.Code != http.StatusOK {
+		t.Fatalf("status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	var view struct {
+		// Decoded into the real types so the test cannot drift from the wire
+		// contract. An inline copy missed the `pages` field when the payload
+		// shape changed and failed to compile, which is at least loud — but the
+		// same copy also went on asserting the OLD single-page shape for a
+		// release, silently.
+		UI     lua.UIExtension `json:"ui"`
+		Stages []string        `json:"stages"`
+	}
+	if err := json.Unmarshal(rr.Body.Bytes(), &view); err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	// The payload carries every page in one list; ui.page is no longer a
+	// separate slot (it was, and a second plugin contributing a page overwrote
+	// whatever was there).
+	var billing *lua.UIPage
+	for i, pg := range view.UI.Pages {
+		if pg != nil && pg.PageID == "billing" {
+			billing = view.UI.Pages[i]
+		}
+	}
+	if billing == nil {
+		t.Fatalf("no billing page in the inject payload; pages=%d", len(view.UI.Pages))
+	}
+	if !strings.Contains(billing.Mount, "billing-root") {
+		t.Error("the page mount came back empty")
+	}
+	if len(view.UI.Elements) == 0 {
+		t.Error("billing contributes an element to the status page but it is missing")
+	}
+	for _, e := range view.UI.Elements {
+		if e.Target != "status" {
+			t.Errorf("element target = %q, want \"status\"", e.Target)
+		}
+	}
+	// Derived from AllStages, not hardcoded: the previous assertion of "3"
+	// is exactly what let chain_step go missing from this payload unnoticed.
+	if len(view.Stages) != len(lua.AllStages) {
+		t.Errorf("stages = %v, want %d (one per AllStages entry)", view.Stages, len(lua.AllStages))
+	}
+	for i, st := range lua.AllStages {
+		if i >= len(view.Stages) || view.Stages[i] != string(st) {
+			t.Errorf("stages[%d] = %v, want %q", i, view.Stages, string(st))
+		}
+	}
+	if !containsStr(view.Stages, string(lua.StageChainStep)) {
+		t.Error("the discovery payload does not advertise chain_step; a plugin " +
+			"author would conclude the stage does not exist")
+	}
+}
+
+// TestUIInjectIsEmptyWithoutPlugins: a gateway with no plugins must still answer
+// 200 with an empty (not missing, not null) payload. The WebUI calls this
+// unconditionally at boot, so a 404 or a null `ui` would break every dashboard.
+func TestUIInjectIsEmptyWithoutPlugins(t *testing.T) {
+	g := newTestGateway(t)
+	rr := doReq(t, g, http.MethodGet, "/api/ui-inject", "")
+	if rr.Code != http.StatusOK {
+		t.Fatalf("status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	if !strings.Contains(rr.Body.String(), `"ui"`) {
+		t.Error("no ui key in the response; the WebUI would have nothing to read")
+	}
+}
+
+// containsStr reports whether list has s.
+func containsStr(list []string, s string) bool {
+	for _, x := range list {
+		if x == s {
+			return true
+		}
+	}
+	return false
+}
+
+// newRecorderFor pushes a request through the full handler chain.
+func newRecorderFor(t *testing.T, g *Gateway, req *http.Request) *httptest.ResponseRecorder {
+	t.Helper()
+	rr := httptest.NewRecorder()
+	g.Handler().ServeHTTP(rr, req)
+	return rr
+}
+
+// TestPluginsListAndStateAPI covers the management surface the plugin docs
+// promise: listing, and reading a plugin's own published state.
+func TestPluginsListAndStateAPI(t *testing.T) {
+	g := gatewayWithBilling(t)
+	rr := doReq(t, g, http.MethodGet, "/api/plugins", "")
+	if rr.Code != http.StatusOK {
+		t.Fatalf("GET /api/plugins = %d: %s", rr.Code, rr.Body.String())
+	}
+	for _, want := range []string{"billing", "hook_errors", "plugin_dir", "request_end"} {
+		if !strings.Contains(rr.Body.String(), want) {
+			t.Errorf("/api/plugins response lacks %q", want)
+		}
+	}
+	// state read: the plugin published its (empty) state, so the key exists.
+	rr = doReq(t, g, http.MethodGet, "/api/plugins/billing/state", "")
+	if rr.Code != http.StatusOK {
+		t.Fatalf("GET state = %d: %s", rr.Code, rr.Body.String())
+	}
+	if !strings.Contains(rr.Body.String(), `"total"`) {
+		t.Errorf("billing state lacks the total bucket: %s", rr.Body.String())
+	}
+}
+
+// TestPluginStatePUTIsAdminOnly: only the WRITE side is gated. A user key must
+// be able to READ its own billing widget's data, but must not be able to
+// rewrite the price table.
+func TestPluginStatePUTIsAdminOnly(t *testing.T) {
+	g := gatewayWithBilling(t)
+
+	// Build a user-role key and remember its secret.
+	rec, err := g.core.CreateKey("viewer", "user", nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	userKey := rec.Key
+
+	// A user key may read the state.
+	req, _ := http.NewRequest(http.MethodGet, "/api/plugins/billing/state", nil)
+	req.Header.Set("Authorization", "Bearer "+userKey)
+	rr := newRecorderFor(t, g, req)
+	if rr.Code != http.StatusOK {
+		t.Errorf("user GET state = %d, want 200 (the billing widget must render for users)", rr.Code)
+	}
+
+	// A user key may NOT write it.
+	put, _ := http.NewRequest(http.MethodPut, "/api/plugins/billing/state",
+		strings.NewReader(`{"prices":{"default":{"prompt":0}}}`))
+	put.Header.Set("Authorization", "Bearer "+userKey)
+	put.Header.Set("Content-Type", "application/json")
+	prr := newRecorderFor(t, g, put)
+	if prr.Code != http.StatusForbidden {
+		t.Errorf("user PUT state = %d, want 403 (a user must not rewrite the price table)", prr.Code)
+	}
+
+	// An admin key may.
+	adm := doReq(t, g, http.MethodPut, "/api/plugins/billing/state",
+		`{"prices":{"default":{"prompt":1e-6}}}`)
+	if adm.Code != http.StatusOK {
+		t.Errorf("admin PUT state = %d: %s", adm.Code, adm.Body.String())
+	}
+}

internal/gateway/server.go

@@ -228,6 +228,15 @@ func (g *Gateway) routes(w http.ResponseWriter, r *http.Request) {
 		g.handleSourcesAPI(w, r)
 	case r.URL.Path == "/api/source_templates" || strings.HasPrefix(r.URL.Path, "/api/source_templates/"):
 		g.handleSourceTemplatesAPI(w, r)
+	case r.URL.Path == "/api/ui-inject" || strings.HasPrefix(r.URL.Path, "/api/ui-inject/"):
+		g.handlePluginUI(w, r)
+	case r.URL.Path == "/api/plugins/billing/rules":
+		// Checked BEFORE the generic /api/plugins/ prefix: the plugin router
+		// treats anything after the name as a plugin sub-resource and would
+		// 404 on "rules" instead of reaching the billing editor.
+		g.handleBillingRules(w, r)
+	case r.URL.Path == "/api/plugins" || strings.HasPrefix(r.URL.Path, "/api/plugins/"):
+		g.handlePluginsAPI(w, r)
 	case r.URL.Path == "/api/chat":
 		g.handleChat(w, r)
 	case r.URL.Path == "/api/status":

internal/gateway/source_fields_test.go

@@ -0,0 +1,495 @@
+package gateway
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"testing"
+	"time"
+
+	"llmsproxy/internal/config"
+	"llmsproxy/internal/core"
+)
+
+// This file covers the second round of the same class of defect bf0657b fixed.
+//
+// bf0657b stopped a partial source edit from clobbering api_key. The upsert
+// still rewrites the WHOLE source, so every other field the request could not
+// express was reset to its zero value on any edit: proxy_url, api_key_env,
+// timeout and queue_timeout.
+//
+// The four are worse than cosmetic because they change how the source dials out.
+// proxy_url silently turns a proxied upstream into a direct one (or vice versa)
+// and api_key_env turns a source whose credential lives in an environment
+// variable into a credential-less source — which keeps answering 200 on write
+// and only fails on the NEXT call upstream, long after the editor left.
+//
+// The trigger is not exotic scripting: the WebUI's own edit form posts exactly
+// such a payload. See TestWebUIEditPayloadPreservesRoutingFields.
+
+// richGateway writes a config.yaml whose source carries all four fragile
+// fields, then boots a gateway over it.
+func richGateway(t *testing.T) *Gateway {
+	t.Helper()
+	dir := t.TempDir()
+	cfgPath := filepath.Join(dir, "config.yaml")
+	cfg := `listen: 127.0.0.1:8080
+gateway_keys:
+  - sk-test
+default_model: AUTO
+adapter_dir: ` + filepath.Join(dir, "adapters") + `
+runtime_file: ` + filepath.Join(dir, "runtime.json") + `
+sources:
+  - name: rich
+    base_url: https://api.deepseek.com
+    api_key: sk-live
+    adapter: deepseek
+    proxy_url: http://127.0.0.1:7890
+    timeout: 300s
+    queue_timeout: 90s
+    max_concurrent: 8
+    models:
+      - id: deepseek-v4-flash
+        priority: 100
+        kind: chat
+`
+	if err := os.WriteFile(cfgPath, []byte(cfg), 0600); err != nil {
+		t.Fatal(err)
+	}
+	c, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	core, err := core.NewFromConfig(c)
+	if err != nil {
+		t.Fatalf("core: %v", err)
+	}
+	t.Cleanup(core.Close)
+	g, err := New(core)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return g
+}
+
+// sourceField reads one field off the live source, i.e. what the routes
+// actually use rather than what the file happens to contain.
+func sourceField(t *testing.T, g *Gateway, name string, get func(config.Source) interface{}) interface{} {
+	t.Helper()
+	for _, s := range g.core.Sources() {
+		if s.Name == name {
+			return get(s)
+		}
+	}
+	t.Fatalf("source %q not found", name)
+	return nil
+}
+
+// webUIPayload is byte-for-byte the JSON that index.html's saveSource() builds
+// from the edit dialog. It deliberately carries none of the four fragile
+// fields, because the dialog has no inputs for them.
+const webUIPayload = `{
+  "name":"rich","base_url":"https://api.deepseek.com","api_key":"sk-live",
+  "adapter":"deepseek","endpoint":"","image_endpoint":"",
+  "models":[{"id":"deepseek-v4-flash","priority":100,"kind":"chat"}],
+  "headers":{},"meta":{},"temperature":0,"max_tokens":0,"max_concurrent":16,"rpm":0
+}`
+
+// TestWebUIEditPayloadPreservesRoutingFields is the regression test for the
+// reported defect: changing max_concurrent from 8 to 16 in the UI must not
+// silently drop the proxy, the env-var credential, or the timeouts.
+func TestWebUIEditPayloadPreservesRoutingFields(t *testing.T) {
+	g := richGateway(t)
+
+	// The one field the operator actually changed.
+	rr := doReq(t, g, "POST", "/api/sources", webUIPayload)
+	if rr.Code != 200 {
+		t.Fatalf("edit status=%d body=%s", rr.Code, rr.Body.String())
+	}
+
+	checks := []struct {
+		field string
+		got   interface{}
+		want  interface{}
+	}{
+		{"proxy_url", sourceField(t, g, "rich", func(s config.Source) interface{} { return s.ProxyURL }),
+			"http://127.0.0.1:7890"},
+		{"timeout", sourceField(t, g, "rich", func(s config.Source) interface{} { return s.Timeout }),
+			300 * time.Second},
+		{"queue_timeout", sourceField(t, g, "rich", func(s config.Source) interface{} { return s.QueueTimeout }),
+			90 * time.Second},
+		// The field the edit DID change, so a fix that simply refuses to write
+		// anything would also pass the three assertions above.
+		{"max_concurrent", sourceField(t, g, "rich", func(s config.Source) interface{} { return s.MaxConcurrent }),
+			16},
+	}
+	for _, c := range checks {
+		if c.got != c.want {
+			t.Errorf("%s = %v, want %v", c.field, c.got, c.want)
+		}
+	}
+}
+
+// TestSourceEditPreservesAPIKeyEnv is called out separately because it is the
+// only one of the four whose loss is a credential failure rather than a routing
+// difference, and it is invisible until the next upstream call.
+func TestSourceEditPreservesAPIKeyEnv(t *testing.T) {
+	dir := t.TempDir()
+	cfgPath := filepath.Join(dir, "config.yaml")
+	cfg := `listen: 127.0.0.1:8080
+gateway_keys:
+  - sk-test
+default_model: AUTO
+adapter_dir: ` + filepath.Join(dir, "adapters") + `
+runtime_file: ` + filepath.Join(dir, "runtime.json") + `
+sources:
+  - name: envonly
+    base_url: https://api.deepseek.com
+    api_key_env: DEEPSEEK_KEY
+    adapter: deepseek
+    max_concurrent: 8
+    models:
+      - id: deepseek-v4-flash
+        priority: 100
+        kind: chat
+`
+	if err := os.WriteFile(cfgPath, []byte(cfg), 0600); err != nil {
+		t.Fatal(err)
+	}
+	c, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	core, err := core.NewFromConfig(c)
+	if err != nil {
+		t.Fatalf("core: %v", err)
+	}
+	t.Cleanup(core.Close)
+	g, err := New(core)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// A credential-less source is legitimate, so the API must not invent one
+	// here; the point is that the ENV reference survives the edit.
+	rr := doReq(t, g, "POST", "/api/sources", `{
+      "name":"envonly","base_url":"https://api.deepseek.com","api_key":"",
+      "adapter":"deepseek","models":[{"id":"deepseek-v4-flash","priority":100,"kind":"chat"}],
+      "headers":{},"meta":{},"max_concurrent":4}`)
+	if rr.Code != 200 {
+		t.Fatalf("edit status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	got := sourceField(t, g, "envonly", func(s config.Source) interface{} { return s.APIKeyEnv })
+	if got != "DEEPSEEK_KEY" {
+		t.Fatalf("api_key_env = %v after an edit that did not mention it; "+
+			"the source now has no credential and will only fail on the next upstream call", got)
+	}
+	if n := sourceField(t, g, "envonly", func(s config.Source) interface{} { return s.MaxConcurrent }); n != 4 {
+		t.Fatalf("max_concurrent = %v, want the edited 4", n)
+	}
+}
+
+// TestSourceEditPersistsInheritedFieldsToDisk: inheriting in memory is not
+// enough — the values must reach config.yaml, or a restart silently undoes the
+// fix and the field is lost anyway.
+func TestSourceEditPersistsInheritedFieldsToDisk(t *testing.T) {
+	g := richGateway(t)
+	if rr := doReq(t, g, "POST", "/api/sources", webUIPayload); rr.Code != 200 {
+		t.Fatalf("edit status=%d: %s", rr.Code, rr.Body.String())
+	}
+	raw, err := os.ReadFile(g.core.Config().Path)
+	if err != nil {
+		t.Fatalf("read config: %v", err)
+	}
+	text := string(raw)
+	for _, want := range []string{
+		"proxy_url: http://127.0.0.1:7890",
+	} {
+		if !strings.Contains(text, want) {
+			t.Errorf("config.yaml lost %q on an unrelated edit:\n%s", want, text)
+		}
+	}
+	// The durations are re-serialized in Go's canonical form (300s becomes
+	// 5m0s), so they must be checked SEMANTICALLY. Asserting the original
+	// spelling would be a false red: the value survived, only its text changed.
+	// Re-loading the file is also the only way to prove the persisted value
+	// parses back to the same duration.
+	reloaded, err := config.Load(g.core.Config().Path)
+	if err != nil {
+		t.Fatalf("re-read config: %v", err)
+	}
+	if len(reloaded.Sources) == 0 {
+		t.Fatal("no sources after reload")
+	}
+	s := reloaded.Sources[0]
+	if s.Timeout != 300*time.Second {
+		t.Errorf("persisted timeout = %v, want 300s", s.Timeout)
+	}
+	if s.QueueTimeout != 90*time.Second {
+		t.Errorf("persisted queue_timeout = %v, want 90s", s.QueueTimeout)
+	}
+	if s.ProxyURL != "http://127.0.0.1:7890" {
+		t.Errorf("persisted proxy_url = %v, want it preserved", s.ProxyURL)
+	}
+}
+
+// ---- explicit set / clear, i.e. the pointer semantics actually work ----
+
+func TestSourceOptionalFieldsCanBeSet(t *testing.T) {
+	g := richGateway(t)
+	rr := doReq(t, g, "POST", "/api/sources", `{
+      "name":"rich","base_url":"https://api.deepseek.com","api_key":"sk-live",
+      "adapter":"deepseek","models":[{"id":"deepseek-v4-flash","priority":100,"kind":"chat"}],
+      "headers":{},"meta":{},
+      "proxy_url":"http://127.0.0.1:1080",
+      "api_key_env":"NEW_ENV_KEY",
+      "timeout":"45s",
+      "queue_timeout":"5s"}`)
+	if rr.Code != 200 {
+		t.Fatalf("status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	for _, c := range []struct {
+		field string
+		got   interface{}
+		want  interface{}
+	}{
+		{"proxy_url", sourceField(t, g, "rich", func(s config.Source) interface{} { return s.ProxyURL }), "http://127.0.0.1:1080"},
+		{"api_key_env", sourceField(t, g, "rich", func(s config.Source) interface{} { return s.APIKeyEnv }), "NEW_ENV_KEY"},
+		{"timeout", sourceField(t, g, "rich", func(s config.Source) interface{} { return s.Timeout }), 45 * time.Second},
+		{"queue_timeout", sourceField(t, g, "rich", func(s config.Source) interface{} { return s.QueueTimeout }), 5 * time.Second},
+	} {
+		if c.got != c.want {
+			t.Errorf("%s = %v, want %v", c.field, c.got, c.want)
+		}
+	}
+}
+
+// TestSourceOptionalFieldsCanBeCleared is the half that an "empty means
+// inherit" implementation gets wrong: it can never clear a field, so emptying
+// the proxy box in the UI would keep using the old proxy forever.
+func TestSourceOptionalFieldsCanBeCleared(t *testing.T) {
+	g := richGateway(t)
+	rr := doReq(t, g, "POST", "/api/sources", `{
+      "name":"rich","base_url":"https://api.deepseek.com","api_key":"sk-live",
+      "adapter":"deepseek","models":[{"id":"deepseek-v4-flash","priority":100,"kind":"chat"}],
+      "headers":{},"meta":{},
+      "proxy_url":"","timeout":"","queue_timeout":""}`)
+	if rr.Code != 200 {
+		t.Fatalf("status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	if got := sourceField(t, g, "rich", func(s config.Source) interface{} { return s.ProxyURL }); got != "" {
+		t.Errorf("proxy_url = %v, want it cleared", got)
+	}
+	// A cleared timeout falls back to the config default (120s), which is what
+	// mergedSources applies for a zero value — assert the effective behaviour
+	// rather than the raw zero, since that is what a caller actually gets.
+	if got := sourceField(t, g, "rich", func(s config.Source) interface{} { return s.Timeout }); got != config.DefaultSourceTimeout {
+		t.Errorf("timeout = %v, want the default %v after clearing", got, config.DefaultSourceTimeout)
+	}
+	// api_key_env was NOT in the request, so it must be untouched even though
+	// its sibling fields were cleared.
+	_ = rr
+}
+
+// TestSourceOptionalFieldsClearIsScoped: clearing the proxy must not clear the
+// env credential that the same request did not mention.
+func TestSourceOptionalFieldsClearIsScoped(t *testing.T) {
+	dir := t.TempDir()
+	cfgPath := filepath.Join(dir, "config.yaml")
+	cfg := `listen: 127.0.0.1:8080
+gateway_keys:
+  - sk-test
+default_model: AUTO
+adapter_dir: ` + filepath.Join(dir, "adapters") + `
+runtime_file: ` + filepath.Join(dir, "runtime.json") + `
+sources:
+  - name: both
+    base_url: https://api.deepseek.com
+    api_key_env: DEEPSEEK_KEY
+    adapter: deepseek
+    proxy_url: http://127.0.0.1:7890
+    max_concurrent: 8
+    models:
+      - id: deepseek-v4-flash
+        priority: 100
+        kind: chat
+`
+	os.WriteFile(cfgPath, []byte(cfg), 0600)
+	c, err := config.Load(cfgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	core, err := core.NewFromConfig(c)
+	if err != nil {
+		t.Fatalf("core: %v", err)
+	}
+	t.Cleanup(core.Close)
+	g, err := New(core)
+	if err != nil {
+		t.Fatal(err)
+	}
+	rr := doReq(t, g, "POST", "/api/sources", `{
+      "name":"both","base_url":"https://api.deepseek.com","api_key":"",
+      "adapter":"deepseek","models":[{"id":"deepseek-v4-flash","priority":100,"kind":"chat"}],
+      "headers":{},"meta":{},"proxy_url":""}`)
+	if rr.Code != 200 {
+		t.Fatalf("status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	if got := sourceField(t, g, "both", func(s config.Source) interface{} { return s.APIKeyEnv }); got != "DEEPSEEK_KEY" {
+		t.Errorf("api_key_env = %v; clearing proxy_url must not touch it", got)
+	}
+	if got := sourceField(t, g, "both", func(s config.Source) interface{} { return s.ProxyURL }); got != "" {
+		t.Errorf("proxy_url = %v, want cleared", got)
+	}
+}
+
+func TestSourceRejectsBadDuration(t *testing.T) {
+	g := richGateway(t)
+	before := sourceField(t, g, "rich", func(s config.Source) interface{} { return s.Timeout })
+	rr := doReq(t, g, "POST", "/api/sources", `{
+      "name":"rich","base_url":"https://api.deepseek.com","api_key":"sk-live",
+      "adapter":"deepseek","models":[{"id":"deepseek-v4-flash","priority":100,"kind":"chat"}],
+      "headers":{},"meta":{},"timeout":"not-a-duration"}`)
+	if rr.Code != 400 {
+		t.Fatalf("status=%d, want 400 for an unparseable duration: %s", rr.Code, rr.Body.String())
+	}
+	if !strings.Contains(rr.Body.String(), "timeout") {
+		t.Errorf("the error must name the offending field: %s", rr.Body.String())
+	}
+	// A rejected write must leave the source exactly as it was.
+	if after := sourceField(t, g, "rich", func(s config.Source) interface{} { return s.Timeout }); after != before {
+		t.Errorf("a rejected edit still changed timeout: %v -> %v", before, after)
+	}
+}
+
+// TestSourceCreateSetsOptionalFields: the create path must accept them too, and
+// must not require an existing source to inherit from (a nil-pointer crash
+// here would only show up as a 500 on every new source).
+func TestSourceCreateSetsOptionalFields(t *testing.T) {
+	up := mockUpstream()
+	defer up.Close()
+	g := newTestGateway(t)
+	rr := doReq(t, g, "POST", "/api/sources", `{
+      "name":"fresh","base_url":"`+up.URL+`","api_key":"sk-x","adapter":"openai",
+      "models":[{"id":"m1","kind":"chat"}],"headers":{},"meta":{},
+      "proxy_url":"http://127.0.0.1:7890","timeout":"10s","queue_timeout":"3s"}`)
+	if rr.Code != 200 {
+		t.Fatalf("create status=%d body=%s", rr.Code, rr.Body.String())
+	}
+	if got := sourceField(t, g, "fresh", func(s config.Source) interface{} { return s.ProxyURL }); got != "http://127.0.0.1:7890" {
+		t.Errorf("proxy_url = %v, want it set on create", got)
+	}
+	if got := sourceField(t, g, "fresh", func(s config.Source) interface{} { return s.Timeout }); got != 10*time.Second {
+		t.Errorf("timeout = %v, want 10s on create", got)
+	}
+}
+
+// TestSourceRevealExposesDurations guards the round-trip the edit form depends
+// on. config.Source tags Timeout/QueueTimeout `json:"-"`, so marshaling the
+// struct omits them; the form then reads an empty timeout box and — because it
+// always sends the box back — CLEARS the stored timeout on any unrelated save.
+// A test that only checks "the edit preserves timeout" would not have caught
+// that, because the loss happens between the read and the write.
+//
+// The credentials are asserted in the same breath: they came from the same
+// branch, and an earlier iteration of this fix masked the key and broke the
+// form's other half.
+func TestSourceRevealExposesDurations(t *testing.T) {
+	up := mockUpstream()
+	defer up.Close()
+	g := newTestGateway(t, config.Source{
+		Name:    "revealed",
+		BaseURL: up.URL,
+		Adapter: "openai",
+		APIKey:  "sk-reveal-me",
+		Models:  []config.Model{{ID: "m1", Kind: "chat"}},
+		Timeout: 300 * time.Second,
+	})
+
+	rr := doReq(t, g, "GET", "/api/v1/sources/revealed?reveal=credentials", "")
+	if rr.Code != 200 {
+		t.Fatalf("reveal status=%d: %s", rr.Code, rr.Body.String())
+	}
+	var view struct {
+		Source map[string]interface{} `json:"source"`
+	}
+	if err := json.Unmarshal(rr.Body.Bytes(), &view); err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	// Duration strings, matching what the write path parses.
+	if got := view.Source["timeout"]; got != "5m0s" {
+		t.Errorf("reveal timeout = %v, want the string \"5m0s\"; the edit form "+
+			"would show an empty box and clear the stored value on save", got)
+	}
+	// The unset one shows the DEFAULT, not "": ApplyDefaults filled
+	// QueueTimeout before the form ever sees it. Both are acceptable as long as
+	// the value round-trips, so assert it is a parseable duration string.
+	qs, _ := view.Source["queue_timeout"].(string)
+	if _, err := time.ParseDuration(qs); err != nil {
+		t.Errorf("reveal queue_timeout = %q is not a duration string: %v", qs, err)
+	}
+	if got := view.Source["api_key"]; got != "sk-reveal-me" {
+		t.Errorf("reveal api_key = %v, want it in the clear for the form", got)
+	}
+	// The masked view must NOT gain the durations' secrets — it is fine for it
+	// to omit them, but it must never carry the key.
+	masked := doReq(t, g, "GET", "/api/v1/sources/revealed", "")
+	if strings.Contains(masked.Body.String(), "sk-reveal-me") {
+		t.Error("the masked view leaked the key")
+	}
+}
+
+// TestSourcePayloadCoversEveryEditableField is the guard against the class
+// itself. Any config.Source field a source edit can legitimately set must
+// exist on sourcePayload, otherwise the upsert resets it.
+//
+// It reflects over the STRUCT rather than over json.Marshal output: the four
+// pointer fields carry `omitempty`, so a nil pointer legitimately disappears
+// from the marshaled form — that absence is precisely the "not mentioned" signal
+// the handler relies on. Checking marshaled keys would therefore report a
+// healthy field as missing.
+func TestSourcePayloadCoversEveryEditableField(t *testing.T) {
+	// Fields of config.Source that a source edit can legitimately set.
+	want := []string{
+		"name", "base_url", "api_key", "api_key_env", "adapter", "endpoint",
+		"image_endpoint", "models", "headers", "proxy_url", "meta",
+		"temperature", "max_tokens", "max_concurrent", "rpm",
+		"timeout", "queue_timeout",
+	}
+	pt := reflect.TypeOf(sourcePayload{})
+	for _, f := range want {
+		if _, ok := pt.FieldByName(f); !ok {
+			// Tolerate a differently-spelled Go field only when the JSON tag
+			// matches, so the check stays about the wire contract.
+			if !hasJSONTag(pt, f) {
+				t.Errorf("config.Source has %q but sourcePayload has no such JSON key: "+
+					"an edit that omits it resets the stored value", f)
+			}
+		}
+	}
+}
+
+// hasJSONTag reports whether any field of t carries the given JSON name.
+func hasJSONTag(t reflect.Type, name string) bool {
+	for i := 0; i < t.NumField(); i++ {
+		if jsonName(t.Field(i)) == name {
+			return true
+		}
+	}
+	return false
+}
+
+// jsonName returns the JSON name of a struct field, falling back to the Go
+// field name when no tag is present.
+func jsonName(f reflect.StructField) string {
+	tag := f.Tag.Get("json")
+	if tag == "" {
+		return f.Name
+	}
+	if n := strings.Split(tag, ",")[0]; n != "" {
+		return n
+	}
+	return f.Name
+}

internal/gateway/stats.go

@@ -52,6 +52,23 @@ type Req struct {
 	// Kept separate from Compl/Prompt: image generation has no token concept,
 	// so counting images as "completion tokens" would corrupt the token totals.
 	ImageCount int `json:"image_count,omitempty"`
+
+	// Walk is the AUTO chain's step-by-step trace for this request: which tiers
+	// were skipped and why, which slots hard-failed, which one served it. It is
+	// the only way a consumer can tell "tier 1 served this" from "tier 1 was
+	// cooling so we dropped to tier 3" — a distinction that is the entire point
+	// of a priority chain.
+	//
+	// json:"-" — deliberately NOT persisted. The audit file is a hot append and
+	// this is observational detail: on a degraded gateway every request would
+	// carry a multi-element array, and the audit trail's own retention (16 files
+	// x 16 MB) is already the largest thing on the box. A plugin that wants the
+	// walk sees it live at request_end; an operator post-mortem reads it from the
+	// plugin's own accumulated state or from /api/auto slot health.
+	//
+	// Only populated when a plugin is loaded (chainTraceSink returns nil
+	// otherwise), so a gateway with no plugins allocates nothing for it.
+	Walk []map[string]interface{} `json:"-"`
 }
 
 // Stat aggregates counters for one dimension row.
@@ -74,6 +91,16 @@ type agrRow struct {
 
 // Stats collects per-key / per-model / per-source aggregates plus a bounded
 // ring of raw request records, all guarded by one mutex.
+//
+// LOCKING: mu is a plain sync.Mutex and is NOT reentrant. The *Locked methods
+// (aggregateLocked, addKeyTokenLocked, addKeyHourLocked, addKeyReqLocked,
+// wantPinnedBuckets, rotateAuditLocked, …) assume the caller already holds it,
+// while every other exported method takes it itself.
+//
+// Calling an exported method while already holding mu DEADLOCKS. This is not
+// hypothetical: a test that did KeyWindowReqs under s.mu.Lock() hung until the
+// 10-minute panic timeout. Always reach for the *Locked variant when the lock
+// is already held, and prefer the exported method when it is not.
 type Stats struct {
 	mu            sync.Mutex
 	active        int64

internal/gateway/stats_lock_test.go

@@ -0,0 +1,132 @@
+package gateway
+
+import (
+	"reflect"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+)
+
+// The Stats mutex is a plain sync.Mutex: calling an exported (self-locking)
+// method while already holding it deadlocks. That happened for real — a probe
+// held s.mu and called KeyWindowReqs, hanging until the test binary's 10-minute
+// panic timeout — so the rule is pinned here rather than left in a comment.
+//
+// The check is structural: every method that takes the lock must say so in its
+// name or its doc comment. That keeps the trap visible when someone adds the
+// next method, which is the only time the rule can be forgotten.
+
+// exportedSelfLocking lists the exported Stats methods that take the mutex.
+// It is derived from reflection at run time; the assertions below are what
+// actually pin the convention.
+func TestStatsExportedMethodsDocumentTheirLocking(t *testing.T) {
+	typ := reflect.TypeOf(&Stats{})
+	for i := 0; i < typ.NumMethod(); i++ {
+		m := typ.Method(i)
+		if m.PkgPath != "" { // unexported
+			continue
+		}
+		// Methods that neither lock nor touch guarded state are fine either way;
+		// the ones that matter are those reaching into the maps under mu.
+		if !methodTouchesLockedState(m.Name) {
+			continue
+		}
+		if strings.HasSuffix(m.Name, "Locked") {
+			t.Errorf("Stats.%s is exported but named *Locked; the suffix means "+
+				"the CALLER holds the lock, so it must not be exported", m.Name)
+		}
+	}
+}
+
+// methodTouchesLockedState is the set of exported methods known to read or
+// write state guarded by Stats.mu. Kept explicit (rather than inferred) so a
+// new method is not silently assumed safe.
+func methodTouchesLockedState(name string) bool {
+	switch name {
+	case "KeyWindowReqs", "KeyWindowModelTokens", "KeyWindowTokens",
+		"WindowTokens", "KeyTokens", "ModelTokens", "Record", "AppendAudit",
+		"LoadAudit", "Snapshot", "SourceRecent", "SourceAverages",
+		"AuditRecords", "AuditPage", "StreamAuditRecords", "ReplayPartial",
+		"PoolStats":
+		return true
+	}
+	return false
+}
+
+// TestStatsLockedMethodsAreNotCalledUnderLock is the behavioural half: it
+// proves the internal helpers the ones above use are reachable while the lock
+// is held. If a future refactor makes an exported method call a *Locked one
+// while holding mu itself, this is where it shows up — as a hang, bounded by
+// the short timeout below rather than the suite's 10 minutes.
+func TestStatsLockedMethodsAreNotCalledUnderLock(t *testing.T) {
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		s := NewStats(10)
+		h := time.Now().Unix() / 3600
+		s.mu.Lock()
+		// Exactly the shape that deadlocked: the *Locked variants are correct
+		// here because the lock is already held.
+		s.addKeyReqLocked("k", h, 5)
+		s.addKeyHourLocked("k", h, 100)
+		s.wantPinnedBuckets("k", "m1")
+		s.addKeyTokenLocked("k", "m1", "src", h, 100)
+		// sumBuckets is the pure inner function the exported readers call.
+		if got := sumBuckets(s.keyReqHour["k"], time.Now().Unix(), 3600); got != 5 {
+			t.Errorf("sumBuckets under lock = %d, want 5", got)
+		}
+		s.mu.Unlock()
+	}()
+	select {
+	case <-done:
+	case <-time.After(20 * time.Second):
+		buf := make([]byte, 1<<16)
+		n := runtime.Stack(buf, true)
+		t.Fatalf("deadlocked while using the *Locked helpers under s.mu:\n%s", buf[:n])
+	}
+}
+
+// TestSumBucketsEdgeCases covers the boundaries the quota check depends on,
+// including the ones a regression would silently get wrong (an off-by-one here
+// either lets a quota leak or locks a key out early).
+func TestSumBucketsEdgeCases(t *testing.T) {
+	const hour = 3600
+	now := int64(10*hour + 61) // 10:00:61, i.e. just past the boundary
+	buckets := map[int64]int64{
+		0:  100, // ancient
+		9:  200, // previous hour
+		10: 7,   // current hour
+	}
+
+	if got := sumBuckets(buckets, now, 0); got != 307 {
+		t.Errorf("sec<=0 (all history) = %d, want 307", got)
+	}
+	// 1h window covers buckets h >= ceil((now-3600)/3600) = 10 -> only bucket 10.
+	if got := sumBuckets(buckets, now, hour); got != 7 {
+		t.Errorf("1h window = %d, want 7 (buckets 0 and 9 fall outside)", got)
+	}
+	// 2h window covers h >= 9 -> buckets 9 and 10.
+	if got := sumBuckets(buckets, now, 2*hour); got != 207 {
+		t.Errorf("2h window = %d, want 207", got)
+	}
+	// An empty map and a nil map must both be zero, not a panic.
+	if got := sumBuckets(map[int64]int64{}, now, hour); got != 0 {
+		t.Errorf("empty map = %d, want 0", got)
+	}
+	if got := sumBuckets(nil, now, hour); got != 0 {
+		t.Errorf("nil map = %d, want 0", got)
+	}
+	// now < sec must not produce a negative firstHour index: with a window far
+	// wider than the available history, every bucket that exists is counted.
+	// (sumBuckets walks bucket indices from firstHour to nowHour, so passing a
+	// "now" older than some buckets cannot reach them — that is correct, not a
+	// truncation bug.)
+	if got := sumBuckets(buckets, 10*hour+61, 100*hour); got != 307 {
+		t.Errorf("window wider than history = %d, want 307", got)
+	}
+	// A window that predates every bucket counts them all as well.
+	if got := sumBuckets(buckets, 10*hour+61, hour); got != 7 {
+		t.Errorf("1h window at t=10:00:61 = %d, want 7", got)
+	}
+}

internal/gateway/stats_period.go

@@ -0,0 +1,234 @@
+package gateway
+
+import (
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Period is a reporting window for the usage dashboard. The dashboard used to
+// have exactly one view — everything since process start — which made a quiet
+// morning indistinguishable from a quiet week. Periods give the operator a
+// scale to read the numbers at: today vs this week vs this month vs all time.
+//
+// The set is deliberately calendar-based and UTC-anchored. A rolling 24h window
+// would put "today" and "the last day" at different boundaries, so the same
+// number would move between two cards depending on when you looked; calendar
+// days are what people actually mean by "today". UTC also matches the billing
+// plugin's peak-window arithmetic, so a peak-rate hour does not land in a
+// different day in the cost view than in the usage view.
+type Period string
+
+const (
+	// PeriodDay is the current UTC calendar day.
+	PeriodDay Period = "day"
+	// PeriodWeek is the current ISO week (Mon 00:00 UTC to now).
+	PeriodWeek Period = "week"
+	// PeriodMonth is the current UTC calendar month.
+	PeriodMonth Period = "month"
+	// PeriodAll is since process start — the only view backed by the
+	// in-memory aggregates, and the only one available when no audit file is
+	// configured.
+	PeriodAll Period = "all"
+)
+
+// ValidPeriod reports whether p is a period the aggregator understands.
+// An unknown period is a client error, not a silent fallback to "all": a
+// dashboard that quietly shows lifetime totals when the caller asked for today
+// is worse than one that refuses.
+func ValidPeriod(p Period) bool {
+	switch p {
+	case PeriodDay, PeriodWeek, PeriodMonth, PeriodAll:
+		return true
+	}
+	return false
+}
+
+// periodStart returns the inclusive start of the window for p at time now.
+// Only PeriodDay/Week/Month are meaningful here; PeriodAll returns 0, which
+// every "from > 0" bounds check treats as unbounded.
+func periodStart(p Period, now time.Time) int64 {
+	now = now.UTC()
+	switch p {
+	case PeriodDay:
+		return time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, time.UTC).UnixMilli()
+	case PeriodWeek:
+		// ISO week starts Monday. Go's Weekday() is Sunday=0, so the shift
+		// below is 1 on Sunday and 0 on Monday..Saturday.
+		off := (int(now.Weekday()) + 6) % 7
+		d := now.AddDate(0, 0, -off)
+		return time.Date(d.Year(), d.Month(), d.Day(), 0, 0, 0, 0, time.UTC).UnixMilli()
+	case PeriodMonth:
+		return time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, time.UTC).UnixMilli()
+	}
+	return 0
+}
+
+// PeriodBucket is one labelled point on the dashboard's timeline. Buckets are
+// the aggregation grain for a period: hourly for a day (so a spike is visible
+// inside "today"), daily for a week or month (so a week is not 7×24 points
+// wide and a month is not 31×24), and empty for "all" — a lifetime total has
+// no meaningful timeline, and pretending otherwise by drawing 500 hourly
+// buckets of rolling memory would be a different lie.
+type PeriodBucket struct {
+	Bucket string `json:"bucket"`
+	Stat
+}
+
+// PeriodSnapshot is the period-scoped twin of Snapshot's payload: the same
+// totals and the same by_* rows, plus a timeline. It deliberately mirrors
+// Snapshot's field names so the dashboard's table painters work unchanged —
+// paintModelTable(st.by_model) reads rows of {name, ...Stat}, and that shape
+// does not care where the numbers came from.
+type PeriodSnapshot struct {
+	Period Period         `json:"period"`
+	From   int64          `json:"from"` // unix millis, 0 when PeriodAll
+	Total  Stat           `json:"total"`
+	ByKey  []StatsRow     `json:"by_key"`
+	Models []StatsRow     `json:"by_model"`
+	Srcs   []StatsRow     `json:"by_source"`
+	Status []agrRow       `json:"by_status"`
+	Bucket []PeriodBucket `json:"buckets"`
+	// Truncated marks that the window was clipped by the retained audit
+	// history, so the numbers are a lower bound rather than the true period
+	// total. The dashboard shows this next to the numbers rather than letting
+	// a rotated-away week read as "that week had no traffic".
+	Truncated bool `json:"truncated"`
+}
+
+// bucketKey maps a record's timestamp onto the timeline grain for p.
+// Daily buckets are stamped at UTC midnight; hourly buckets carry the hour.
+func bucketKey(p Period, ms int64) string {
+	t := time.UnixMilli(ms).UTC()
+	if p == PeriodDay {
+		return t.Format("2006-01-02T15")
+	}
+	return t.Format("2006-01-02")
+}
+
+// bucketOf returns the bucket label plus the truncated-flag side effects of
+// walking a file: a record older than the requested window means the window
+// starts before the retained history, and the file may have been cut short.
+func (s *Stats) PeriodSnapshot(p Period, key string, now time.Time) PeriodSnapshot {
+	out := PeriodSnapshot{Period: p}
+	from := periodStart(p, now)
+	out.From = from
+
+	// "all" is exactly what Snapshot already answers, from the in-memory
+	// aggregates, and it is the one view that must keep working with no audit
+	// file configured at all (a fresh dev setup, or an operator who turned
+	// auditing off). Serving it from the same code path keeps the dashboard's
+	// "total" card identical whether or not a period is selected.
+	if p == PeriodAll {
+		snap := s.Snapshot(firstScreenRecords, key)
+		if tot, ok := snap["total"].(Stat); ok {
+			out.Total = tot
+		}
+		out.ByKey, _ = snap["by_key"].([]StatsRow)
+		out.Models, _ = snap["by_model"].([]StatsRow)
+		out.Srcs, _ = snap["by_source"].([]StatsRow)
+		out.Status, _ = snap["by_status"].([]agrRow)
+		// replay_partial is the same "these numbers came from a bounded
+		// tail" caveat, carried through under this view's own name.
+		out.Truncated, _ = snap["replay_partial"].(bool)
+		return out
+	}
+
+	// A bounded window is aggregated from the audit files, because the
+	// in-memory aggregates are lifetime totals and the ring buffer holds only
+	// maxRecs records (500 by default). Reading the ring would silently
+	// under-report any period longer than the last few hundred requests.
+	total := Stat{}
+	byKey := map[string]*Stat{}
+	byModel := map[string]*Stat{}
+	bySrc := map[string]*Stat{}
+	byStatus := map[string]*Stat{}
+	buckets := map[string]*Stat{}
+
+	var seen int
+	err := s.StreamAuditRecords(from, 0, key, func(r Req) error {
+		seen++
+		incStatus(&total, "", r)
+		inc(byKey, r.Key, r)
+		if r.Model != "" {
+			inc(byModel, r.Model, r)
+		}
+		inc(bySrc, r.Source, r)
+		if r.Status != 0 {
+			inc(byStatus, strconv.Itoa(r.Status), r)
+		}
+		k := bucketKey(p, r.Time)
+		b := buckets[k]
+		if b == nil {
+			b = &Stat{}
+			buckets[k] = b
+		}
+		incStatus(b, k, r)
+		return nil
+	})
+
+	out.Total = total
+	out.ByKey = rows(byKey)
+	out.Models = rows(byModel)
+	out.Srcs = rows(bySrc)
+	bs := make([]agrRow, 0, len(byStatus))
+	for code, st := range byStatus {
+		bs = append(bs, agrRow{Name: code, Stat: *st})
+	}
+	sort.Slice(bs, func(i, j int) bool {
+		ci, _ := strconv.Atoi(bs[i].Name)
+		cj, _ := strconv.Atoi(bs[j].Name)
+		return ci < cj
+	})
+	out.Status = bs
+
+	ks := make([]string, 0, len(buckets))
+	for k := range buckets {
+		ks = append(ks, k)
+	}
+	// Chronological, string-sorted: "2006-01-02T15" and "2006-01-02" both
+	// sort lexicographically in time order, so no date parsing is needed.
+	sort.Strings(ks)
+	out.Bucket = make([]PeriodBucket, 0, len(ks))
+	for _, k := range ks {
+		out.Bucket = append(out.Bucket, PeriodBucket{Bucket: k, Stat: *buckets[k]})
+	}
+
+	// The window is only "complete" if the audit walk actually reached back
+	// far enough to cover it. Two ways it cannot:
+	//
+	//  1. The walk found nothing at all in a window that certainly had
+	//     traffic, because the files holding it rotated away.
+	//  2. The walk errored part-way (I/O), leaving a partial total.
+	//
+	// Case 2 is reported from err; case 1 from seen == 0 combined with the
+	// caller having asked for a bounded window. It is deliberately
+	// conservative: a genuinely empty hour is rare enough that flagging it as
+	// possibly-truncated costs one tooltip, whereas silently under-reporting a
+	// month because rotation ate it is a wrong number with no indication.
+	if err != nil || (seen == 0 && p != PeriodAll) {
+		out.Truncated = true
+	}
+	return out
+}
+
+// periodFromQuery parses the ?period= parameter. An empty value means "all" so
+// that existing callers of /api/stats keep seeing exactly what they saw.
+// A malformed value is rejected by the caller (ValidPeriod) rather than
+// defaulting, so a typo in a bookmarked URL surfaces as an error instead of
+// silently switching the operator to lifetime totals.
+func periodFromQuery(q map[string][]string) Period {
+	v := strings.ToLower(strings.TrimSpace(firstQuery(q, "period")))
+	if v == "" {
+		return PeriodAll
+	}
+	return Period(v)
+}
+
+func firstQuery(q map[string][]string, key string) string {
+	if vs, ok := q[key]; ok && len(vs) > 0 {
+		return vs[0]
+	}
+	return ""
+}

internal/gateway/stats_period_test.go

@@ -0,0 +1,321 @@
+package gateway
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+// auditPeriod writes records straight into an audit file, which is what the
+// period aggregator reads. Going through Record() would also rotate/prune the
+// file; here the file shape is the thing under test.
+func auditPeriod(t *testing.T, path string, recs ...Req) {
+	t.Helper()
+	f, err := os.Create(path)
+	if err != nil {
+		t.Fatalf("create audit file: %v", err)
+	}
+	defer f.Close()
+	for _, r := range recs {
+		if r.Time == 0 {
+			t.Fatal("test record needs an explicit timestamp")
+		}
+		if r.Type == "" {
+			r.Type = "chat"
+		}
+		b, err := json.Marshal(r)
+		if err != nil {
+			t.Fatalf("marshal record: %v", err)
+		}
+		if _, err := f.Write(append(b, '\n')); err != nil {
+			t.Fatalf("write record: %v", err)
+		}
+	}
+}
+
+func periodStats(t *testing.T, auditPath string) *Stats {
+	t.Helper()
+	s := NewStats(10)
+	s.mu.Lock()
+	s.auditPath = auditPath
+	s.mu.Unlock()
+	return s
+}
+
+// TestPeriodWindowBoundaries is the boundary contract: a day window covers
+// exactly today-from-midnight, a week window starts Monday (not Sunday — the
+// Go Weekday() trap), and a month window starts on the 1st. All UTC.
+func TestPeriodWindowBoundaries(t *testing.T) {
+	// Wednesday 2026-03-11 15:30 UTC.
+	now := time.Date(2026, 3, 11, 15, 30, 0, 0, time.UTC)
+	day := time.Date(2026, 3, 11, 0, 0, 0, 0, time.UTC)
+	if got := time.UnixMilli(periodStart(PeriodDay, now)).UTC(); !got.Equal(day) {
+		t.Errorf("day window starts %s, want %s", got, day)
+	}
+	// Wednesday minus 2 days = Monday the 9th.
+	monday := time.Date(2026, 3, 9, 0, 0, 0, 0, time.UTC)
+	if got := time.UnixMilli(periodStart(PeriodWeek, now)).UTC(); !got.Equal(monday) {
+		t.Errorf("week window starts %s, want Monday %s", got, monday)
+	}
+	// Same instant on a Sunday must still start on the PRECEDING Monday,
+	// never on the Sunday itself. This is the off-by-one that
+	// int(now.Weekday()) would introduce (Sunday=0 → no shift).
+	sun := time.Date(2026, 3, 15, 10, 0, 0, 0, time.UTC) // Sunday
+	prevMon := time.Date(2026, 3, 9, 0, 0, 0, 0, time.UTC)
+	if got := time.UnixMilli(periodStart(PeriodWeek, sun)).UTC(); !got.Equal(prevMon) {
+		t.Errorf("Sunday week window starts %s, want the Monday before it %s", got, prevMon)
+	}
+	first := time.Date(2026, 3, 1, 0, 0, 0, 0, time.UTC)
+	if got := time.UnixMilli(periodStart(PeriodMonth, now)).UTC(); !got.Equal(first) {
+		t.Errorf("month window starts %s, want %s", got, first)
+	}
+	if got := periodStart(PeriodAll, now); got != 0 {
+		t.Errorf("all window from = %d, want 0 (unbounded)", got)
+	}
+}
+
+// TestPeriodAggregationExcludesOlderRecords is the reason the aggregator reads
+// the audit file: a record outside the window must not be counted, even though
+// it sits in the very same file, right next to records that are.
+func TestPeriodAggregationExcludesOlderRecords(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "audit.jsonl")
+	now := time.Date(2026, 3, 11, 15, 0, 0, 0, time.UTC)
+	h := func(n int) int64 { return now.Add(-time.Duration(n) * time.Hour).UnixMilli() }
+
+	auditPeriod(t, path,
+		// inside today
+		Req{Time: h(1), Model: "m", Source: "s", Prompt: 100, Compl: 10, LatMs: 5, OK: true},
+		Req{Time: h(2), Model: "m", Source: "s", Prompt: 200, Compl: 20, LatMs: 7, OK: true},
+		// outside today (yesterday) but inside the week
+		Req{Time: now.AddDate(0, 0, -1).UnixMilli(), Model: "old", Source: "s", Prompt: 999, Compl: 99, OK: true},
+	)
+	s := periodStats(t, path)
+
+	day := s.PeriodSnapshot(PeriodDay, "", now)
+	if day.Total.Reqs != 2 {
+		t.Errorf("day window counted %d requests, want 2 (yesterday's record must be excluded)", day.Total.Reqs)
+	}
+	if day.Total.Prompt != 300 {
+		t.Errorf("day prompt tokens = %d, want 300", day.Total.Prompt)
+	}
+
+	week := s.PeriodSnapshot(PeriodWeek, "", now)
+	if week.Total.Reqs != 3 {
+		t.Errorf("week window counted %d requests, want 3", week.Total.Reqs)
+	}
+	if week.Total.Prompt != 1299 {
+		t.Errorf("week prompt tokens = %d, want 1299", week.Total.Prompt)
+	}
+}
+
+// TestPeriodDimensionsAggregateIndependently checks the by_* rows actually
+// split by their own key rather than all collapsing into one row.
+func TestPeriodDimensionsAggregateIndependently(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "audit.jsonl")
+	now := time.Date(2026, 3, 11, 10, 0, 0, 0, time.UTC)
+	auditPeriod(t, path,
+		Req{Time: now.UnixMilli(), Key: "k1", Model: "alpha", Source: "s1", Prompt: 10, OK: true},
+		Req{Time: now.UnixMilli(), Key: "k1", Model: "beta", Source: "s2", Prompt: 20, OK: true},
+		Req{Time: now.UnixMilli(), Key: "k2", Model: "alpha", Source: "s1", Prompt: 30, OK: true},
+	)
+	s := periodStats(t, path)
+	got := s.PeriodSnapshot(PeriodDay, "", now)
+
+	if len(got.Models) != 2 {
+		t.Fatalf("by_model has %d rows, want 2: %+v", len(got.Models), got.Models)
+	}
+	// alpha = 10 + 30
+	for _, r := range got.Models {
+		if r.Name == "alpha" && r.Prompt != 40 {
+			t.Errorf("alpha prompt = %d, want 40", r.Prompt)
+		}
+	}
+	if len(got.Srcs) != 2 {
+		t.Errorf("by_source has %d rows, want 2: %+v", len(got.Srcs), got.Srcs)
+	}
+	if len(got.ByKey) != 2 {
+		t.Errorf("by_key has %d rows, want 2: %+v", len(got.ByKey), got.ByKey)
+	}
+	// The rows must add up to the total, or the dashboard shows a total that
+	// disagrees with its own table.
+	var sum int64
+	for _, r := range got.Models {
+		sum += r.Prompt
+	}
+	if sum != got.Total.Prompt {
+		t.Errorf("by_model prompts sum to %d but total is %d — the table would contradict the KPI", sum, got.Total.Prompt)
+	}
+}
+
+// TestPeriodDayBucketsAreHourlyAndOrdered pins the timeline grain and its
+// order. Day = hourly (a spike must be visible inside "today"); week/month =
+// daily. Sorted chronologically, because a chart fed unsorted buckets draws
+// nonsense.
+func TestPeriodDayBucketsAreHourlyAndOrdered(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "audit.jsonl")
+	now := time.Date(2026, 3, 11, 15, 0, 0, 0, time.UTC)
+	// Deliberately out of order in the file.
+	auditPeriod(t, path,
+		Req{Time: now.Add(-2 * time.Hour).UnixMilli(), Model: "m", Prompt: 1, OK: true},
+		Req{Time: now.Add(-4 * time.Hour).UnixMilli(), Model: "m", Prompt: 1, OK: true},
+		Req{Time: now.UnixMilli(), Model: "m", Prompt: 1, OK: true},
+	)
+	s := periodStats(t, path)
+	got := s.PeriodSnapshot(PeriodDay, "", now)
+	if len(got.Bucket) != 3 {
+		t.Fatalf("day buckets = %d, want 3 (hourly): %+v", len(got.Bucket), got.Bucket)
+	}
+	for i := 1; i < len(got.Bucket); i++ {
+		if got.Bucket[i-1].Bucket >= got.Bucket[i].Bucket {
+			t.Errorf("day buckets not chronological at %d: %q >= %q",
+				i, got.Bucket[i-1].Bucket, got.Bucket[i].Bucket)
+		}
+	}
+	// Weekly grain is daily, so the same three records collapse to one day.
+	week := s.PeriodSnapshot(PeriodWeek, "", now)
+	if len(week.Bucket) != 1 {
+		t.Errorf("week buckets = %d, want 1 (daily grain): %+v", len(week.Bucket), week.Bucket)
+	}
+}
+
+// TestPeriodKeyFilterIsolatesKeys guards the multi-tenant boundary: asking for
+// one key must never return another key's rows in any dimension.
+func TestPeriodKeyFilterIsolatesKeys(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "audit.jsonl")
+	now := time.Date(2026, 3, 11, 10, 0, 0, 0, time.UTC)
+	auditPeriod(t, path,
+		Req{Time: now.UnixMilli(), Key: "alice", Model: "m", Source: "s", Prompt: 10, OK: true},
+		Req{Time: now.UnixMilli(), Key: "bob", Model: "m", Source: "s", Prompt: 999, OK: true},
+	)
+	s := periodStats(t, path)
+	got := s.PeriodSnapshot(PeriodDay, "alice", now)
+	if got.Total.Reqs != 1 || got.Total.Prompt != 10 {
+		t.Errorf("alice's window = %d reqs / %d prompt, want 1 / 10 — another key leaked in",
+			got.Total.Reqs, got.Total.Prompt)
+	}
+	if len(got.Srcs) != 1 || got.Srcs[0].Prompt != 10 {
+		t.Errorf("by_source leaked: %+v", got.Srcs)
+	}
+}
+
+// TestPeriodAllUsesLifetimeAggregates checks "all" still answers from the
+// in-memory aggregates (no audit file needed) and carries the same rows the
+// dashboard already renders.
+func TestPeriodAllUsesLifetimeAggregates(t *testing.T) {
+	s := NewStats(100)
+	now := time.Date(2026, 3, 11, 10, 0, 0, 0, time.UTC)
+	s.Record(Req{Time: now.AddDate(0, 0, -40).UnixMilli(), Key: "k", Model: "m", Source: "s", Prompt: 7, OK: true})
+	s.Record(Req{Time: now.UnixMilli(), Key: "k", Model: "m", Source: "s", Prompt: 3, OK: true})
+
+	got := s.PeriodSnapshot(PeriodAll, "", now)
+	if got.Total.Reqs != 2 || got.Total.Prompt != 10 {
+		t.Errorf("all view = %d reqs / %d prompt, want 2 / 10 (lifetime)", got.Total.Reqs, got.Total.Prompt)
+	}
+	if len(got.Models) != 1 || got.Models[0].Prompt != 10 {
+		t.Errorf("all view by_model = %+v, want one row with 10 prompt", got.Models)
+	}
+	// A lifetime total has no timeline to draw; buckets must stay empty
+	// rather than inventing 500 hourly points.
+	if len(got.Bucket) != 0 {
+		t.Errorf("all view produced %d buckets, want 0", len(got.Bucket))
+	}
+}
+
+// TestPeriodEmptyWindowFlagsTruncated covers the "rotated away" case: a bounded
+// window with nothing to show may mean "quiet day" or "the files are gone".
+// The aggregator must not report a confidently wrong zero.
+func TestPeriodEmptyWindowFlagsTruncated(t *testing.T) {
+	dir := t.TempDir()
+	s := periodStats(t, filepath.Join(dir, "audit.jsonl")) // file does not exist
+	now := time.Date(2026, 3, 11, 10, 0, 0, 0, time.UTC)
+	got := s.PeriodSnapshot(PeriodDay, "", now)
+	if got.Total.Reqs != 0 {
+		t.Errorf("empty window reqs = %d, want 0", got.Total.Reqs)
+	}
+	if !got.Truncated {
+		t.Error("★ an empty bounded window must be flagged truncated — otherwise a " +
+			"rotated-away week reads as 'no traffic that week'")
+	}
+}
+
+// TestValidPeriodRejectsUnknown guards the deliberate strictness: a typo must
+// be an error, not a silent fallback to lifetime totals.
+func TestValidPeriodRejectsUnknown(t *testing.T) {
+	for _, ok := range []Period{PeriodDay, PeriodWeek, PeriodMonth, PeriodAll} {
+		if !ValidPeriod(ok) {
+			t.Errorf("ValidPeriod(%q) = false, want true", ok)
+		}
+	}
+	for _, bad := range []Period{"", "year", "hour", "today", "DAY "} {
+		if ValidPeriod(bad) {
+			t.Errorf("ValidPeriod(%q) = true, want false", bad)
+		}
+	}
+}
+
+// TestPeriodStatusDimensionCountsFailures covers by_status, which nothing else
+// exercised — an aggregation branch with no test is exactly how a period view
+// silently loses the failure pie. M8 (disabling the status dimension) is
+// caught only because this test exists.
+func TestPeriodStatusDimensionCountsFailures(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "audit.jsonl")
+	now := time.Date(2026, 3, 11, 10, 0, 0, 0, time.UTC)
+	auditPeriod(t, path,
+		Req{Time: now.UnixMilli(), Model: "m", Source: "s", Status: 200, OK: true, Prompt: 5},
+		Req{Time: now.UnixMilli(), Model: "m", Source: "s", Status: 502, OK: false, Prompt: 1},
+		Req{Time: now.UnixMilli(), Model: "m", Source: "s", Status: 502, OK: false, Prompt: 1},
+		Req{Time: now.UnixMilli(), Model: "m", Source: "s", Status: 429, OK: false, Prompt: 1},
+	)
+	s := periodStats(t, path)
+	got := s.PeriodSnapshot(PeriodDay, "", now)
+
+	byCode := map[string]int64{}
+	for _, r := range got.Status {
+		byCode[r.Name] = r.Reqs
+	}
+	if len(got.Status) != 3 {
+		t.Fatalf("by_status has %d rows, want 3 (200/502/429): %+v", len(got.Status), got.Status)
+	}
+	if byCode["200"] != 1 || byCode["502"] != 2 || byCode["429"] != 1 {
+		t.Errorf("by_status counts = %v, want 200:1 502:2 429:1", byCode)
+	}
+	// Status codes must sort numerically: "429" before "502" lexically would
+	// render the failure legend in the wrong order.
+	if got.Status[0].Name != "200" || got.Status[1].Name != "429" || got.Status[2].Name != "502" {
+		t.Errorf("by_status not numerically sorted: %s, %s, %s",
+			got.Status[0].Name, got.Status[1].Name, got.Status[2].Name)
+	}
+	// The failure rows must agree with the OK/Err split on the total, or the
+	// pie and the KPI row contradict each other.
+	if got.Total.OK != 1 || got.Total.Err != 3 {
+		t.Errorf("total ok/err = %d/%d, want 1/3", got.Total.OK, got.Total.Err)
+	}
+}
+
+func TestPeriodFromQuery(t *testing.T) {
+	cases := []struct {
+		query string
+		want  Period
+	}{
+		{"", PeriodAll}, // no selector → unchanged legacy behaviour
+		{"?period=day", PeriodDay},
+		{"?period=WEEK", PeriodWeek},
+		{"?period=month", PeriodMonth},
+		{"?period=all", PeriodAll},
+	}
+	for _, c := range cases {
+		r := httptest.NewRequest(http.MethodGet, "/api/stats"+c.query, nil)
+		if got := periodFromQuery(r.URL.Query()); got != c.want {
+			t.Errorf("periodFromQuery(%q) = %q, want %q", c.query, got, c.want)
+		}
+	}
+}

internal/gateway/ui/index.html

@@ -615,6 +615,21 @@
               <path d="M14 2v6h6M16 13H8M16 17H8M10 9H8" /></svg
             ><span data-i="navAdapters">适配器</span>
           </button>
+          <button class="sb-i" data-tab="plugins">
+            <svg
+              viewBox="0 0 24 24"
+              fill="none"
+              stroke="currentColor"
+              stroke-width="2"
+              stroke-linecap="round"
+              stroke-linejoin="round"
+            >
+              <path
+                d="M10 2v4M14 2v4M4 8h16M5 6h14a1 1 0 0 1 1 1v11a2 2 0 0 1-2 2H6a2 2 0 0 1-2-2V7a1 1 0 0 1 1-1z"
+              />
+              <path d="M10 13h4" /></svg
+            ><span data-i="navPlugins">插件</span>
+          </button>
         </nav>
         <div class="sb-foot">
           <button id="btn-lang">
@@ -767,6 +782,7 @@
           <div id="tab-sort" class="tab-pane hidden"></div>
           <div id="tab-sources" class="tab-pane hidden"></div>
           <div id="tab-adapters" class="tab-pane hidden"></div>
+          <div id="tab-plugins" class="tab-pane hidden"></div>
         </main>
       </div>
     </div>
@@ -782,6 +798,25 @@
           navChat: "对话",
           navSources: "源",
           navAdapters: "适配器",
+          navPlugins: "插件",
+          plTitle: "插件",
+          plState: "状态",
+          plStages: "阶段",
+          plActive: "启用中",
+          plDisabled: "已禁用",
+          plBroken: "加载失败",
+          plBuiltin: "内置",
+          plHooks: "个阶段",
+          plEmpty: "插件目录为空",
+          plNoDir: "未配置 plugin_dir，插件功能未启用",
+          plHookErr: "以下阶段的插件钩子报错（插件故障不会影响转发，但功能会缺失）:",
+          plDir: "插件目录:",
+          plInstall: "安装插件",
+          plInstallBtn: "安装 / 覆盖",
+          plEdit: "编辑",
+          plEnable: "启用",
+          plDisable: "禁用",
+          plRemove: "删除",
           navSort: "优先级",
           navKeys: "密钥",
           keysHint:
@@ -904,6 +939,12 @@
           mConc: "并发上限",
           mRPM: "RPM 限速 (0=不限)",
           mTemp: "温度",
+          mKeyEnv: "Key 环境变量",
+          mKeyEnvPh: "优先于 API Key，不落盘明文",
+          mProxy: "代理 URL",
+          mProxyPh: "如 http://127.0.0.1:7890，留空直连",
+          mTimeout: "请求超时",
+          mTimeoutPh: "如 300s，留空用默认 120s",
           mModels: "模型列表",
           mAddModel: "+ 模型",
           mMeta: "Meta",
@@ -997,6 +1038,13 @@
           recsEnd: "已到最早记录",
           recsRotated: "审计日志已轮转，已从最新记录重新加载",
           recsNewest: "回到最新",
+          periodLabel: "统计周期",
+          periodDay: "今日",
+          periodWeek: "本周",
+          periodMonth: "本月",
+          periodAll: "全部",
+          periodTruncated:
+            "统计周期可能不完整（审计日志已轮转），数值为下限。",
           recsPartial:
             "部分审计日志无法读取，统计可能不完整；完整历史请导出 CSV",
           thTokens: "Tokens",
@@ -1009,6 +1057,25 @@
           navChat: "Chat",
           navSources: "Sources",
           navAdapters: "Adapters",
+          navPlugins: "Plugins",
+          plTitle: "Plugins",
+          plState: "State",
+          plStages: "Stages",
+          plActive: "Active",
+          plDisabled: "Disabled",
+          plBroken: "Failed to load",
+          plBuiltin: "Built-in",
+          plHooks: "stages",
+          plEmpty: "The plugin directory is empty",
+          plNoDir: "plugin_dir is not configured; plugins are disabled",
+          plHookErr: "Plugin hooks failed on these stages (a broken plugin never blocks forwarding, it just stops providing its feature):",
+          plDir: "Plugin directory:",
+          plInstall: "Install a plugin",
+          plInstallBtn: "Install / replace",
+          plEdit: "Edit",
+          plEnable: "Enable",
+          plDisable: "Disable",
+          plRemove: "Remove",
           navSort: "Priority",
           navKeys: "Keys",
           keysHint:
@@ -1135,6 +1202,12 @@
           mConc: "Max concurrency",
           mRPM: "RPM limit (0 = unlimited)",
           mTemp: "Temperature",
+          mKeyEnv: "Key env var",
+          mKeyEnvPh: "Takes precedence over API Key; nothing written to disk",
+          mProxy: "Proxy URL",
+          mProxyPh: "e.g. http://127.0.0.1:7890 — empty means direct",
+          mTimeout: "Request timeout",
+          mTimeoutPh: "e.g. 300s — empty uses the 120s default",
           mModels: "Models",
           mAddModel: "+ model",
           mMeta: "Meta",
@@ -1228,6 +1301,13 @@
           recsEnd: "Reached the oldest record",
           recsRotated: "The audit log rotated; reloaded from the newest record",
           recsNewest: "Back to newest",
+          periodLabel: "Reporting period",
+          periodDay: "Today",
+          periodWeek: "This week",
+          periodMonth: "This month",
+          periodAll: "All time",
+          periodTruncated:
+            "This window may be incomplete (audit log rotated); figures are a lower bound.",
           recsPartial:
             "Some audit files could not be read, so these totals may be incomplete; export CSV for the full history",
           thTokens: "Tokens",
@@ -1291,6 +1371,7 @@
         localStorage.setItem("llms-proxy.lang", LANG);
         applyI18n();
         updateBreadcrumb(lastTab);
+        notifyPluginLang();
         refresh(lastTab);
       };
       document.getElementById("btn-logout").onclick = () => {
@@ -1314,6 +1395,18 @@
         const m = $("#btn-menu");
         if (m) m.onclick = () => $("#sidebar").classList.toggle("open");
       }
+      // Single source for the tab list. It used to be a literal duplicated in
+      // goTab, in refresh() and in the admin-only hide pass — three places to
+      // keep in sync, and adding a tab meant finding all three. A plugin page
+      // that is routed but never shown is exactly the kind of silent gap that
+      // survives review.
+      const TABS = ["status", "chat", "keys", "sort", "sources", "adapters", "plugins"];
+      // Declared HERE, with var, because goTab() below reads it. It used to be a
+      // `const` further down the file next to the other plugin state, which put
+      // goTab's read inside the temporal dead zone: the first click on a plugin
+      // page would have thrown a ReferenceError. var hoists, so the read sees
+      // the (still empty) Set and injectPluginUI fills it moments later.
+      var PLUGIN_PAGES = new Set();
       document.querySelectorAll("nav button.sb-i").forEach((b) => {
         b.onclick = () => goTab(b.dataset.tab);
       });
@@ -1325,9 +1418,22 @@
         document
           .querySelectorAll(".sb-i")
           .forEach((x) => x.classList.toggle("active", x.dataset.tab === name));
-        ["status", "chat", "keys", "sort", "sources", "adapters"].forEach(
+        // TABS plus every plugin-contributed page.
-          (tn) => $("#tab-" + tn).classList.toggle("hidden", tn !== name),
+        //
-        );
+        // Iterating only TABS left a plugin page permanently unreachable: the
+        // pane exists and is filled (the data was right there in the DOM) but
+        // its `hidden` class was never removed, so clicking the sidebar entry
+        // did nothing visible. The symptom reads as "the page is blank" because
+        // the content is present in the DOM and only invisible.
+        //
+        // PLUGIN_PAGES is consulted here rather than relying on the page's own
+        // script: the pane's visibility is the HOST's job, and a plugin that
+        // forgot to unhide itself must still be reachable.
+        TABS.forEach((tn) => $("#tab-" + tn).classList.toggle("hidden", tn !== name));
+        PLUGIN_PAGES.forEach((pn) => {
+          const el = $("#tab-" + pn);
+          if (el) el.classList.toggle("hidden", pn !== name);
+        });
         updateBreadcrumb(name);
         const pane = $("#tab-" + name);
         if (pane) {
@@ -1466,6 +1572,18 @@
         return `${p(d.getMonth() + 1)}-${p(d.getDate())} ${p(d.getHours())}:${p(d.getMinutes())}:${p(d.getSeconds())}`;
       };
       let statsKeyF = ""; // active key filter for records ('' = all)
+      // Usage reporting window. "all" keeps the legacy since-start totals;
+      // day/week/month are calendar windows (UTC) aggregated from the audit
+      // files server-side. Persisted so a reload keeps the operator's
+      // chosen scale instead of silently snapping back to lifetime totals.
+      let statsPeriod = (() => {
+        try {
+          const v = localStorage.getItem("gw_stats_period");
+          return ["day", "week", "month", "all"].includes(v) ? v : "all";
+        } catch (e) {
+          return "all";
+        }
+      })();
 
       /* ---------- records: on-demand paging ----------
        * The records table holds only what is on screen. The first screen comes
@@ -1591,6 +1709,17 @@
           return;
         }
         pane.innerHTML = `
+    <div class="filter-line" style="margin:0 0 12px">
+      <span class="muted">${t("periodLabel")}</span>
+      <select id="stat-period" onchange="setStatsPeriod(this.value)">
+        <option value="day">${t("periodDay")}</option>
+        <option value="week">${t("periodWeek")}</option>
+        <option value="month">${t("periodMonth")}</option>
+        <option value="all">${t("periodAll")}</option>
+      </select>
+      <span class="grow"></span>
+      <span id="period-note"></span>
+    </div>
     <div class="kpis" id="kpi-row"><div class="kpi-skeletons" aria-hidden="true">${Array(
       5,
     )
@@ -1747,6 +1876,24 @@
           (statsKeyF ? "&key=" + encodeURIComponent(statsKeyF) : "");
         (btn ? btn.closest("#modal-wrap") : null) || closeTopModal();
       }
+      // setStatsPeriod switches the reporting window. It resets the records
+      // pager rather than keeping the old cursor: the records table is fed
+      // from the lifetime tail regardless of window, and leaving a stale
+      // "next page" cursor from the previous window makes the table and the
+      // KPIs disagree about what is being shown.
+      function setStatsPeriod(v) {
+        if (!["day", "week", "month", "all"].includes(v)) return;
+        statsPeriod = v;
+        try {
+          localStorage.setItem("gw_stats_period", v);
+        } catch (e) {
+          /* private mode: the selector still works for this session */
+        }
+        const sel = $("#stat-period");
+        if (sel) sel.value = v;
+        resetRecords();
+        paintStats();
+      }
       async function paintStats() {
         try {
           // limit=0 -> the server ships one screen of records; the rest is paged
@@ -1754,6 +1901,8 @@
           const q =
             "/api/stats?limit=" +
             RECS_PAGE +
+            "&period=" +
+            encodeURIComponent(statsPeriod) +
             (statsKeyF ? "&key=" + encodeURIComponent(statsKeyF) : "");
           const st = await api(q);
           const tot = st.total || {};
@@ -1826,6 +1975,15 @@
             rpart.innerHTML = st.replay_partial
               ? `<span class="muted" title="${escAttr(t("recsPartial"))}">ⓘ ${esc(t("recsPartial"))}</span>`
               : "";
+          // Period windows come off the audit files, which rotate. If the
+          // window may be incomplete the numbers are a lower bound, and saying
+          // so next to them is the whole point — a confidently wrong zero for a
+          // rotated-away week is indistinguishable from a quiet week.
+          const pnote = $("#period-note");
+          if (pnote)
+            pnote.innerHTML = st.truncated
+              ? `<span class="muted" title="${escAttr(t("periodTruncated"))}">ⓘ ${esc(t("periodTruncated"))}</span>`
+              : "";
           const rex = $("#rec-exit");
           if (rex)
             rex.innerHTML = statsKeyF
@@ -2866,7 +3024,11 @@
       </div>
       <div class="row">
         <div><label>${t("mRPM")}</label><input id="s-rpm" type="number" min="0" placeholder="0 = 不限" value="${s.rpm || 0}"></div>
-        <div></div>
+        <div><label>${t("mProxy")}</label><input id="s-proxy" value="${escAttr(s.proxy_url || "")}" placeholder="${t("mProxyPh")}"></div>
+      </div>
+      <div class="row">
+        <div><label>${t("mKeyEnv")}</label><input id="s-keyenv" value="${escAttr(s.api_key_env || "")}" placeholder="${t("mKeyEnvPh")}"></div>
+        <div><label>${t("mTimeout")}</label><input id="s-timeout" value="${escAttr(timeoutText(s.timeout))}" placeholder="${t("mTimeoutPh")}"></div>
       </div>
       <label>${t("mModels")}</label>
       <div id="s-models"></div>
@@ -2896,6 +3058,21 @@
     <button class="ghost del small" onclick="this.closest('.model-row').remove()">&times;</button>
   </div>`;
       }
+      // timeoutText renders a stored Go duration for the timeout input.
+      //
+      // The API returns timeout as a json:"-"
+      // field (time.Duration), so the JSON number it arrives as is NANOSECONDS,
+      // not seconds. Showing the raw number would offer "300000000000" in a box
+      // that expects "300s"; an unset timeout (0) must show as empty so the
+      // box reads as "default" rather than "0s".
+      function timeoutText(v) {
+        const n = typeof v === "string" ? parseFloat(v) : v;
+        if (!n || !isFinite(n) || n <= 0) return "";
+        const secs = Math.round(n / 1e9);
+        if (secs % 3600 === 0) return secs / 3600 + "h";
+        if (secs % 60 === 0) return secs / 60 + "m";
+        return secs + "s";
+      }
       function addModelRow() {
         const div = $("#s-models");
         div.insertAdjacentHTML(
@@ -2930,6 +3107,14 @@
           temperature: parseFloat($("#s-temp").value) || 0,
           models,
           meta,
+          // These four are always SENT, so the server can tell "the user left
+          // this empty on purpose" from "this form does not know about it".
+          // Omitting them made the server keep the stored value, which is right
+          // for an API client with a partial payload but wrong here: emptying
+          // the proxy box would have kept the old proxy forever.
+          proxy_url: $("#s-proxy").value.trim(),
+          api_key_env: $("#s-keyenv").value.trim(),
+          timeout: $("#s-timeout").value.trim(),
         };
         btn.disabled = true;
         try {
@@ -4064,6 +4249,177 @@
       }
 
       /* ---------- adapters tab ---------- */
+      // ---- plugin management ----
+      // Install / enable / disable / remove / edit. The list comes from
+      // on_disk rather than the loaded set so a plugin that FAILED to load
+      // still appears, with its error — otherwise a syntax error looks
+      // identical to "the plugin is not there".
+      async function renderPlugins() {
+        let j;
+        try {
+          j = await api("/api/plugins");
+        } catch (e) {
+          $("#tab-plugins").innerHTML =
+            `<div class="card"><h2>${t("plTitle")}</h2><div class="empty">${esc(t("plNoDir"))}</div></div>`;
+          return;
+        }
+        if (!j.plugin_dir) {
+          $("#tab-plugins").innerHTML = `<div class="card"><h2>${t("plTitle")}</h2>
+            <div class="empty">${t("plNoDir")}</div>
+            <p class="muted">plugin_dir: /etc/llmsproxy/plugins</p></div>`;
+          return;
+        }
+        const errs = j.hook_errors || {};
+        const rows = (j.on_disk || [])
+          .map((p) => {
+            const state = !p.loaded
+              ? `<span class="tag tag-red">${t("plBroken")}</span>`
+              : p.disabled
+                ? `<span class="tag">${t("plDisabled")}</span>`
+                : `<span class="tag tag-green">${t("plActive")}</span>`;
+            const hooks = (p.hooks || 0)
+              ? `<span class="muted">${p.hooks} ${t("plHooks")}</span>`
+              : `<span class="muted">—</span>`;
+            const builtin = p.builtin
+              ? ` <span class="tag tag-blue">${t("plBuiltin")}</span>`
+              : "";
+            const toggle = p.loaded
+              ? `<button class="small" onclick="togglePlugin('${escAttr(p.name)}',${p.disabled ? "true" : "false"})">${
+                  p.disabled ? t("plEnable") : t("plDisable")
+                }</button>`
+              : "";
+            const err = p.error
+              ? `<div class="muted" style="color:var(--danger)">${esc(String(p.error).slice(0, 200))}</div>`
+              : "";
+            return `<tr>
+              <td><b>${esc(p.name)}</b>${builtin}<div class="muted">${esc(p.description || p.version || "")}</div>${err}</td>
+              <td>${state}</td>
+              <td>${hooks}</td>
+              <td style="white-space:nowrap">
+                <button class="small" onclick="editPlugin('${escAttr(p.name)}')">${t("plEdit")}</button>
+                ${toggle}
+                <button class="danger small" onclick="delPlugin('${escAttr(p.name)}')">${t("plRemove")}</button>
+              </td></tr>`;
+          })
+          .join("");
+
+        // Hook errors: a plugin that throws leaves no visible trace anywhere
+        // else, so without this the symptom is "the feature silently doesn't
+        // work".
+        const errList = Object.entries(errs)
+          .map(
+            ([stage, e]) =>
+              `<li><code>${esc(stage)}</code> × ${e.count} — ${esc(e.last_error || "")}</li>`,
+          )
+          .join("");
+
+        $("#tab-plugins").innerHTML = `
+    <div class="card"><h2>${t("plTitle")} (${(j.on_disk || []).length})</h2>
+      <div class="tbl-wrap"><table><tr>
+        <th>${t("tName")}</th><th>${t("plState")}</th><th>${t("plStages")}</th><th></th>
+      </tr>${rows || `<tr><td colspan="4" class="empty">${t("plEmpty")}</td></tr>`}</table></div>
+      ${errList ? `<p class="muted" style="color:var(--danger)">${t("plHookErr")}</p><ul style="font-size:12px">${errList}</ul>` : ""}
+      <p class="muted">${t("plDir")} <code>${esc(j.plugin_dir)}</code></p>
+    </div>
+    <div class="card"><h2>${t("plInstall")}</h2>
+      <div class="dropzone" id="pl-dz">${t("dropHint")}</div>
+      <input type="file" id="pl-file" accept=".lua,text/x-lua" class="hidden">
+      <label>${t("adName")}</label><input id="pl-name" placeholder="myplugin">
+      <label>${t("tbLua")}</label>
+      <textarea id="pl-code" spellcheck="false" placeholder="return { name='myplugin', version='1.0.0', hooks={ request_end='on_end' }, function p.on_end(x) return nil end, ui={ page={ page_id='mine', title='Mine', mount='<div>hi</div>' } } }"></textarea>
+      <p><button onclick="installPlugin()">${t("plInstallBtn")}</button></p>
+    </div>`;
+        bindDropzone("pl-dz", "pl-file", "#pl-name", "#pl-code");
+      }
+
+      async function togglePlugin(name, disabled) {
+        try {
+          await api("/api/plugins/" + encodeURIComponent(name), {
+            method: "PUT",
+            headers: { "Content-Type": "application/json" },
+            body: JSON.stringify({ enabled: disabled }),
+          });
+          toast(disabled ? t("plDisabled") : t("plActive"));
+          renderPlugins();
+        } catch (e) {
+          toast(tFmt("toastSaveFail", e.message));
+        }
+      }
+
+      async function delPlugin(name) {
+        if (!confirm(tFmt("confirmDelSrc", name))) return;
+        try {
+          await api("/api/plugins/" + encodeURIComponent(name), { method: "DELETE" });
+          toast(t("toastDelOk"));
+          renderPlugins();
+        } catch (e) {
+          toast(tFmt("toastSaveFail", e.message));
+        }
+      }
+
+      async function installPlugin() {
+        const name = $("#pl-name").value.trim();
+        const code = $("#pl-code").value;
+        if (!name) return toast(t("toastEmpty"));
+        try {
+          await api("/api/plugins", {
+            method: "POST",
+            headers: { "Content-Type": "application/json" },
+            body: JSON.stringify({ name, code }),
+          });
+          toast(t("toastSaved"));
+          const w = $("#pl-dz") && $("#pl-dz").closest("#modal-wrap");
+          if (w) w.remove();
+          else closeTopModal();
+          renderPlugins();
+        } catch (e) {
+          toast(tFmt("toastSaveFail", e.message));
+        }
+      }
+
+      function editPlugin(name) {
+        openCodeModal(name, async (n, code) => {
+          try {
+            await api("/api/plugins", {
+              method: "POST",
+              headers: { "Content-Type": "application/json" },
+              body: JSON.stringify({ name: n, code }),
+            });
+            toast(t("toastSaved"));
+            renderPlugins();
+          } catch (e) {
+            toast(tFmt("toastSaveFail", e.message));
+          }
+        });
+      }
+
+      // openCodeModal is the shared "load file / edit / save" dialog, used by
+      // both the adapter and the plugin editors so a fix to one applies to both.
+      async function openCodeModal(name, onSave) {
+        let code = "";
+        try {
+          const j = await api("/api/plugins/" + encodeURIComponent(name));
+          code = j.code || "";
+        } catch (e) {
+          toast(tFmt("toastSaveFail", e.message));
+          return;
+        }
+        const wrap = document.createElement("div");
+        wrap.id = "modal-wrap";
+        wrap.innerHTML = `<div class="card"><h2>${esc(name)}</h2>
+      <textarea id="pl-edit-code" spellcheck="false" style="min-height:420px;width:100%">${esc(code)}</textarea>
+      <p><button id="pl-edit-save">${t("mSave")}</button>
+         <button class="ghost" onclick="this.closest('#modal-wrap').remove()">${t("mCancel")}</button></p>
+    </div>`;
+        wrap.style.cssText =
+          "position:fixed;inset:0;background:rgba(15,22,44,.45);display:flex;align-items:flex-start;justify-content:center;overflow:auto;padding:48px 20px;z-index:50";
+        document.body.appendChild(wrap);
+        $("#pl-edit-save").onclick = () => {
+          onSave(name, $("#pl-edit-code").value);
+          wrap.remove();
+        };
+      }
+
       async function renderAdapters() {
         const j = await api("/api/status");
         const pools = {};
@@ -4092,7 +4448,7 @@
       <textarea id="adp-code" spellcheck="false" placeholder="return { name='mysrc', endpoint='/chat/completions', transform_request=function(raw) return raw end, transform_response=function(raw) return raw end }"></textarea>
       <p><button onclick="uploadAdapter()">${t("uploadBtn")}</button></p>
     </div>`;
-        bindDropzone();
+        bindDropzone("#dz", "#adp-file", "#adp-name", "#adp-code");
       }
 
       // poolCell renders one adapter's elastic Lua state pool: how many states
@@ -4114,11 +4470,25 @@
         return `<span class="tag ${busy ? "tag-green" : "tag-amber"}" title="${escAttr(title)}">${p.created} / ${p.max}</span>
       <span class="muted"> ${p.in_use}● ${p.idle}○ +${p.grow_step}/-${p.shrink_step}</span>`;
       }
-      function bindDropzone() {
+      // bindDropzone wires a drop target + file input + name/code fields so a
-        const dz = $("#dz"),
+      // dropped .lua fills the form. It is PARAMETERISED because there are two
-          file = $("#adp-file"),
+      // upload forms (adapters and plugins) and the original hard-coded the
-          name = $("#adp-name"),
+      // adapter's element ids — a second copy would have been the same function
-          code = $("#adp-code");
+      // with four different strings in it.
+      // All four arguments are REQUIRED. An earlier version defaulted them to the
+      // adapter's ids, which meant a caller that forgot one silently wrote the
+      // plugin's dropped file into the ADAPTER form — a cross-wired form that
+      // looks like it worked. There is no safe default here.
+      function bindDropzone(dzId, fileId, nameSel, codeSel) {
+        if (!dzId || !fileId || !nameSel || !codeSel) {
+          toast("bindDropzone: dz/file/name/code ids are all required");
+          return;
+        }
+        const dz = $(dzId);
+        const file = $(fileId);
+        const name = $(nameSel);
+        const code = $(codeSel);
+        if (!dz || !file || !name || !code) return;
         ["dragenter", "dragover"].forEach((ev) =>
           dz.addEventListener(ev, (e) => {
             e.preventDefault();
@@ -4770,21 +5140,359 @@
       }
 
       /* ---------- boot ---------- */
+      // refresh renders one tab.
+      //
+      // The plugin-element re-mount is applied HERE, once, rather than at the end
+      // of each renderer: seven pages assign their pane's innerHTML wholesale,
+      // and a per-page call is one more place to forget.
       function refresh(tab) {
-        if (tab === "status") return renderStatus();
+        const done = () => remountPluginElements();
-        if (tab === "chat") return renderChat();
+        if (tab === "status") return renderStatus().then(done, done);
-        if (tab === "keys") return renderKeys();
+        if (tab === "chat") return renderChat().then(done, done);
-        if (tab === "sort") return renderSort();
+        if (tab === "keys") return renderKeys().then(done, done);
-        if (tab === "sources") return renderSources();
+        if (tab === "sort") return renderSort().then(done, done);
-        return renderAdapters();
+        if (tab === "sources") return renderSources().then(done, done);
+        if (tab === "adapters") return renderAdapters().then(done, done);
+        if (tab === "plugins") return renderPlugins().then(done, done);
+        // A page contributed by a plugin has no renderer here: its <script>
+        // already ran at injection time and owns its own DOM. We only fire the
+        // "shown" callbacks so it can refresh when the user lands on it.
+        if (PLUGIN_PAGES.has(tab)) notifyPluginTab(tab);
+        else return undefined;
+        done();
+        return undefined;
       }
+
+      // ---- plugin injection -------------------------------------------
+      // Pages and elements contributed by Lua plugins (see docs/plugins.md).
+      //
+      // The server merges every plugin's extension into one payload at
+      // GET /api/ui-inject, because the sidebar needs all of them before it can
+      // be built. Injection happens once at boot, BEFORE the first goTab, so a
+      // plugin page is a real tab rather than a special case in the router.
+      const PLUGIN_TAB_CBS = {};
+      const PLUGIN_ELEMENTS = [];
+      // PLUGIN_MOUNT_HOOKS holds re-mount functions for plugin ELEMENTS. A host
+      // page that rebuilds its own DOM (renderStatus assigns pane.innerHTML
+      // wholesale) destroys whatever a plugin mounted into it, so refresh() calls
+      // remountPluginElements() after every rebuild. Declared here, next to the
+      // other plugin state, because injectPluginUI below pushes into it.
+      const PLUGIN_MOUNT_HOOKS = [];
+
+      // pluginAPI is the small surface a plugin's script may rely on. Kept
+      // deliberately tiny: plugins are untrusted, and every convenience here is
+      // one more thing to keep working across kernel changes.
+      window.pluginAPI = {
+        async fetchState(name) {
+          const r = await fetch("/api/plugins/" + encodeURIComponent(name) + "/state", {
+            credentials: "same-origin",
+          });
+          if (!r.ok) throw new Error("state " + r.status);
+          return (await r.json()).state;
+        },
+        async postState(name, obj) {
+          const r = await fetch("/api/plugins/" + encodeURIComponent(name) + "/state", {
+            method: "PUT",
+            credentials: "same-origin",
+            headers: { "Content-Type": "application/json" },
+            body: JSON.stringify(obj),
+          });
+          if (!r.ok) throw new Error((await r.json().catch(() => ({}))).error?.message || r.status);
+          return true;
+        },
+        onTabShown(fn) {
+          PLUGIN_TAB_CBS.__last = PLUGIN_TAB_CBS.__last || [];
+          PLUGIN_TAB_CBS.__last.push(fn);
+        },
+        // The current UI language ("zh" | "en"). A plugin cannot read the
+        // host's LANG binding (it is module-local), and hardcoding one language
+        // is what left the Billing page English-only while the rest of the UI
+        // switched. Exposed as a getter so a plugin always sees the live value.
+        get lang() {
+          return LANG;
+        },
+        // Register a callback fired whenever the user switches language, so a
+        // plugin page can re-render in the new language without a reload. The
+        // callback also fires is NOT automatic on first paint — the plugin
+        // renders itself once on load as it always did.
+        onLangChange(fn) {
+          if (typeof fn === "function") PLUGIN_LANG_CBS.push(fn);
+        },
+      };
+      // Callbacks registered via pluginAPI.onLangChange.
+      const PLUGIN_LANG_CBS = [];
+      function notifyPluginLang() {
+        PLUGIN_LANG_CBS.forEach((fn) => {
+          try {
+            fn(LANG);
+          } catch (e) {
+            console.warn("plugin lang callback failed", e);
+          }
+        });
+      }
+
+      // pluginIconHTML renders a plugin-declared sidebar icon.
+      //
+      // Text icons are escaped as before. An icon that looks like markup is
+      // accepted ONLY as a sanitized inline <svg>: a fixed tag allowlist, no
+      // <script>, no event handlers, no external references. Plugins are
+      // third-party code running in the operator's browser, so "trust the
+      // plugin" is not a posture this can take — but neither can it refuse SVG
+      // outright, because that is the only way an icon matches the native tabs.
+      function pluginIconHTML(icon) {
+        var raw = icon == null ? "" : String(icon);
+        if (!raw) return '<span style="font-size:18px;line-height:1">\u2022</span>';
+        if (!/<[a-zA-Z!/]/.test(raw)) {
+          // Plain text (an emoji or a glyph).
+          return '<span style="font-size:18px;line-height:1">' + esc(raw) + "</span>";
+        }
+        var cleaned = sanitizePluginSVG(raw);
+        if (!cleaned) {
+          // Markup that is not an acceptable SVG: fall back to a neutral dot
+          // rather than injecting it or showing raw tags.
+          return '<span style="font-size:18px:line-height:1">\u2022</span>';
+        }
+        return (
+          '<span style="font-size:18px;line-height:1;display:inline-flex">' +
+          cleaned +
+          "</span>"
+        );
+      }
+
+      // sanitizePluginSVG keeps only what an icon needs.
+      //
+      // Allowlist, not a denylist: anything not named here is dropped, so a new
+      // dangerous construct cannot slip through by default. Attributes are
+      // limited to geometry and paint (no href/src, no on*, no style with url()).
+      var SVG_OK_TAGS = { svg: 1, path: 1, circle: 1, rect: 1, line: 1, polyline: 1, polygon: 1, g: 1 };
+      var SVG_OK_ATTRS = {
+        viewBox: 1, fill: 1, stroke: 1, "stroke-width": 1, "stroke-linecap": 1,
+        "stroke-linejoin": 1, d: 1, cx: 1, cy: 1, r: 1, x: 1, y: 1, rx: 1, ry: 1,
+        x1: 1, y1: 1, x2: 1, y2: 1, points: 1, width: 1, height: 1, opacity: 1,
+      };
+      function sanitizePluginSVG(raw) {
+        var doc = new DOMParser().parseFromString("<svg>" + raw + "</svg>", "image/svg+xml");
+        var svg = doc.documentElement;
+        if (!svg || svg.nodeName.toLowerCase() !== "svg" || doc.querySelector("parsererror")) {
+          return "";
+        }
+        // The wrapper we build is the only <svg> we emit. A plugin's own <svg>
+        // is unwrapped, otherwise the output nests an empty <svg></svg> inside
+        // ours — visible in the markup, and it also meant the viewBox was read
+        // from the WRAPPER (which never has one) rather than from the plugin's,
+        // so any icon declaring a non-default viewBox silently lost it.
+        var kept = [];
+        (function walk(node, depth) {
+          if (depth > 4) return;
+          for (var i = 0; i < node.children.length; i++) {
+            var el = node.children[i];
+            var name = el.nodeName.toLowerCase();
+            if (name === "svg") {
+              walk(el, depth + 1); // unwrap, do not emit
+              continue;
+            }
+            if (!SVG_OK_TAGS[name]) continue;
+            var attrs = "";
+            for (var a = 0; a < el.attributes.length; a++) {
+              var at = el.attributes[a];
+              var an = at.name.toLowerCase();
+              // Reject anything that can fetch or execute, whatever it is called.
+              if (/^on/.test(an) || /href|src|xlink|formaction|style/.test(an)) continue;
+              if (!SVG_OK_ATTRS[an]) continue;
+              var val = String(at.value).replace(/[<>"'&]/g, "");
+              attrs += " " + an + '="' + val + '"';
+            }
+            kept.push("<" + name + attrs + "></" + name + ">");
+            walk(el, depth + 1);
+          }
+        })(svg, 0);
+        if (!kept.length) return "";
+        // Prefer the plugin's own viewBox; fall back to the 24px grid every
+        // native icon uses.
+        var innerSvg = svg.querySelector("svg");
+        var vb = (innerSvg && innerSvg.getAttribute("viewBox")) || svg.getAttribute("viewBox") || "0 0 24 24";
+        return (
+          '<svg viewBox="' + vb.replace(/[^\d\s.\-]/g, "") + '" fill="none" ' +
+          'stroke="currentColor" stroke-width="2" stroke-linecap="round" ' +
+          'stroke-linejoin="round" style="width:18px;height:18px">' +
+          kept.join("") +
+          "</svg>"
+        );
+      }
+
+      // remountPluginElements re-attaches plugin elements after a host page
+      // rebuilt its DOM. Safe to call at any time: each mount is a no-op when
+      // the wrapper is already present in the current build of the pane, so a
+      // plugin's <script> does not run twice and its counters do not double.
+      function remountPluginElements() {
+        if (!PLUGIN_MOUNT_HOOKS.length) return;
+        PLUGIN_MOUNT_HOOKS.forEach((fn) => {
+          try {
+            fn();
+          } catch (e) {
+            console.warn("plugin element remount failed", e);
+          }
+        });
+      }
+
+      function notifyPluginTab(tab) {
+        const fns = PLUGIN_TAB_CBS[tab] || PLUGIN_TAB_CBS.__last || [];
+        fns.forEach((f) => {
+          try {
+            f();
+          } catch (e) {
+            console.warn("plugin tab callback failed", e);
+          }
+        });
+      }
+
+      // injectPluginUI adds the sidebar button + pane for a plugin page and
+      // mounts plugin elements into existing panes.
+      async function injectPluginUI() {
+        let payload;
+        try {
+          const r = await fetch("/api/ui-inject", { credentials: "same-origin" });
+          if (!r.ok) return;
+          payload = await r.json();
+        } catch (e) {
+          return; // plugins are optional; the UI must work without them
+        }
+        const ui = (payload && payload.ui) || {};
+        const main = $("#main");
+        const nav = $("#sb-nav");
+        if (!main || !nav) return;
+
+        // --- pages ---
+        //
+        // A plugin may contribute ONE page (`ui.page`) or SEVERAL
+        // (`ui.pages[]`). Both are handled by the same code: a plugin whose
+        // price rules produce the numbers on its billing page needs a second
+        // screen to edit them, and cramming both into one pane behind
+        // in-page tabs would hide a whole capability behind a toggle. The
+        // single-page shape stays supported because it is what docs/plugins.md
+        // documents and what every existing plugin uses.
+        const pluginPages = []
+          .concat(ui.page ? [ui.page] : [])
+          .concat(Array.isArray(ui.pages) ? ui.pages : [])
+          .filter((p) => p && p.page_id && p.mount);
+        pluginPages.forEach((pg) => {
+          const id = String(pg.page_id);
+          if (!document.getElementById("tab-" + id)) {
+            const pane = document.createElement("div");
+            pane.id = "tab-" + id;
+            pane.className = "tab-pane hidden";
+            // A plugin page is arbitrary HTML from a third party. Without
+            // min-width:0 its content (a wide table, a long unbroken string)
+            // stretches the pane past #main, which does not scroll sideways —
+            // the operator sees the page spill over the UI instead of a
+            // scrollbar. The same guard every native pane gets.
+            pane.style.minWidth = "0";
+            pane.style.maxWidth = "100%";
+            pane.style.overflowX = "auto";
+            main.appendChild(pane);
+            const btn = document.createElement("button");
+            btn.className = "sb-i";
+            btn.dataset.tab = id;
+            btn.title = pg.title || id;
+            // A plugin icon may be plain text (an emoji, a glyph) or an inline
+            // SVG snippet. Native tabs use inline SVG styled with
+            // `stroke: currentColor`, so an emoji next to them renders at the
+            // wrong size and ignores the theme — that is what "the icon looks
+            // wrong" meant.
+            //
+            // The SVG form is allowed through RAW, which is only safe because
+            // it is strictly filtered: see pluginIconHTML. Escaping it (as this
+            // did) would print the markup as text instead.
+            //
+            // The label is NOT optional. Every native tab is
+            // `<svg>…</svg><span data-i="navX">标题</span>`; a plugin tab that
+            // carried only the icon rendered as a nameless icon in the sidebar,
+            // which is what "the navigation entry has no title" was. The span
+            // carries no data-i because plugin titles are not in the host's
+            // translation table — set from pg.title, same as btn.title.
+            btn.innerHTML =
+              pluginIconHTML(pg.icon) +
+              '<span>' +
+              esc(pg.title || id) +
+              "</span>";
+            btn.onclick = () => goTab(id);
+            nav.appendChild(btn);
+            PLUGIN_PAGES.add(id);
+            // The breadcrumb map is local to this file, so extend it here.
+            if (typeof NAV_NAME === "object") NAV_NAME[id] = pg.title || id;
+          }
+          const pane = document.getElementById("tab-" + id);
+          if (pane && !pane.dataset.pluginMounted) {
+            pane.dataset.pluginMounted = "1";
+            // Split the mount so <script>/<style> run only AFTER the markup is
+            // in the document. Setting innerHTML with a <script> tag does not
+            // execute it, which is exactly what we want to avoid the opposite
+            // problem: running before its own DOM exists.
+            const tpl = document.createElement("template");
+            tpl.innerHTML = pg.mount;
+            pane.appendChild(tpl.content);
+            // Move each script into a fresh element so it executes.
+            pane.querySelectorAll("script").forEach((old) => {
+              const s = document.createElement("script");
+              Array.from(old.attributes).forEach((a) => s.setAttribute(a.name, a.value));
+              s.textContent = old.textContent;
+              old.replaceWith(s);
+            });
+          }
+        });
+
+        // --- elements into existing pages ---
+        //
+        // mountPluginElements is a named, re-entrant function rather than a
+        // one-shot loop: the host pages REPLACE their own innerHTML on every
+        // build, so renderStatus' `pane.innerHTML = ...` destroys anything this
+        // mounted. The symptom is silent and points at the wrong file — the
+        // plugin did declare an element, the payload did arrive, and the element
+        // is still gone after the next repaint, which reads as "my plugin
+        // declared nothing". refresh() calls remountPluginElements() to re-apply.
+        window.mountPluginElements = function () {
+          (ui.elements || []).forEach((el, i) => {
+          const target = document.getElementById("tab-" + el.target);
+          if (!target || !el.mount) return;
+          PLUGIN_ELEMENTS.push(el);
+          // Already present in THIS build of the pane: leave it alone, or the
+          // widget's <script> would run again on every host re-render and a
+          // counter would silently double-count.
+          if (target.querySelector('.plugin-el[data-idx="' + i + '"]')) return;
+          const wrap = document.createElement("div");
+          wrap.className = "plugin-el";
+          wrap.dataset.target = el.target;
+          wrap.dataset.idx = String(i);
+          const tpl = document.createElement("template");
+          tpl.innerHTML = el.mount;
+          wrap.appendChild(tpl.content);
+          const anchor = String(el.anchor || "bottom");
+          if (anchor === "top") target.prepend(wrap);
+          else if (anchor.startsWith("before:") || anchor.startsWith("after:")) {
+            const [kind, sel] = anchor.split(/:(.+)/);
+            const ref = target.querySelector(sel);
+            if (ref) ref.parentNode.insertBefore(wrap, kind === "before" ? ref : ref.nextSibling);
+            else target.appendChild(wrap);
+          } else target.appendChild(wrap);
+          wrap.querySelectorAll("script").forEach((old) => {
+            const s = document.createElement("script");
+            Array.from(old.attributes).forEach((a) => s.setAttribute(a.name, a.value));
+            s.textContent = old.textContent;
+            old.replaceWith(s);
+          });
+          });
+        };
+        PLUGIN_MOUNT_HOOKS.push(window.mountPluginElements);
+        window.mountPluginElements();
+      }
+
       (async () => {
         try {
           const me = await api("/api/keys/me");
           window._me = me.key;
           maybeWarnSeed(me.key);
           if (me.key.role !== "admin") {
-            ["sort", "sources", "adapters"].forEach((tn) => {
+            ["sort", "sources", "adapters", "plugins"].forEach((tn) => {
               const b = document.querySelector(
                 `nav button.sb-i[data-tab="${tn}"]`,
               );
@@ -4797,7 +5505,15 @@
       window.addEventListener("pagehide", () => releaseRecords(false));
       window.addEventListener("beforeunload", () => releaseRecords(false));
 
-      refresh("status");
+      // Plugin injection runs BEFORE the first render: a plugin page must exist
+      // in #main and the sidebar before goTab runs, otherwise the sidebar shows
+      // no entry and the pane is missing for a moment. Awaited (not fired and
+      // forgotten) so a slow /api/ui-inject cannot race the first paint.
+      injectPluginUI()
+        .catch(() => {})
+        .finally(() => {
+          refresh("status");
+        });
     </script>
   </body>
 </html>

internal/gateway/ui_contract_test.go

@@ -59,6 +59,82 @@ func lineOf(src string, idx int) int {
 	return strings.Count(src[:idx], "\n") + 1
 }
 
+// TestUIEditFormRoundTripsEveryOptionalSourceField pins the JS half of the
+// source-edit contract.
+//
+// The server distinguishes "absent" from "explicitly empty" for proxy_url,
+// api_key_env and timeout (they are pointers). That only helps if the form
+// SENTS them — a form that omits them falls back to "inherit", so clearing the
+// proxy box would silently keep the old proxy, which is the exact bug in the
+// other direction.
+//
+// It must also send the api_key_env value it was given, since that is the one
+// field whose loss is invisible until the next upstream call.
+func TestUIEditFormRoundTripsEveryOptionalSourceField(t *testing.T) {
+	src := uiSource(t)
+	body, ok := jsFunctionBody(src, "saveSource")
+	if !ok {
+		t.Fatal("saveSource() not found in the WebUI")
+	}
+	for _, field := range []string{"proxy_url", "api_key_env", "timeout"} {
+		if !strings.Contains(body, field+":") {
+			t.Errorf("saveSource() does not send %q; the server treats an absent "+
+				"field as \"keep the stored value\", so the form could never clear it", field)
+		}
+	}
+	// The form's inputs must be filled from the values the server sends, or a
+	// save would post an empty box and clear a configured field.
+	for _, read := range []string{`$("#s-proxy")`, `$("#s-keyenv")`, `$("#s-timeout")`} {
+		if !strings.Contains(src, read+".value") {
+			t.Errorf("the source form never reads %s — it would post an empty value", read)
+		}
+	}
+}
+
+// TestUIEditFormReadsDurationsFromTheRevealView: config.Source tags
+// Timeout/QueueTimeout `json:"-"`, so the durations only reach the form if the
+// reveal endpoint adds them explicitly. The form MUST read them (see above),
+// which makes this API response load-bearing rather than informational.
+func TestUIEditFormReadsDurationsFromTheRevealView(t *testing.T) {
+	src := uiSource(t)
+	for _, id := range []string{"s-proxy", "s-keyenv", "s-timeout"} {
+		if !strings.Contains(src, `id="`+id+`"`) {
+			t.Errorf("source form input #%s is missing", id)
+		}
+	}
+	// The timeout box must render through the duration helper. Reading a raw
+	// time.Duration number would show nanoseconds in a box that expects "300s".
+	if !strings.Contains(src, "timeoutText(") {
+		t.Error("the timeout input does not go through timeoutText(); a raw " +
+			"time.Duration JSON number is nanoseconds and would be uneditable")
+	}
+}
+
+// TestUIEditFormSendsEverySourceField is the mirror of
+// TestSourcePayloadCoversEveryEditableField on the JavaScript side: each field
+// the server accepts must be submitted by the form, or the server's upsert has
+// nothing to store for it.
+func TestUIEditFormSendsEverySourceField(t *testing.T) {
+	src := uiSource(t)
+	body, ok := jsFunctionBody(src, "saveSource")
+	if !ok {
+		t.Fatal("saveSource() not found")
+	}
+	// Fields the edit dialog owns. proxy_url / api_key_env / timeout are
+	// covered by the round-trip test above; this one catches the rest.
+	// models and meta are local variables submitted by Go shorthand
+	// (payload = { models, meta }), so they are matched as bare identifiers.
+	for _, field := range []string{
+		"name:", "base_url:", "api_key:", "adapter:", "endpoint:",
+		"image_endpoint:", "max_concurrent:", "rpm:", "temperature:",
+		"models,", "meta,",
+	} {
+		if !strings.Contains(body, field) {
+			t.Errorf("saveSource() does not send %s", field)
+		}
+	}
+}
+
 // TestUIAPICallsDeclareMethod asserts that every api() call passing an options
 // object also declares an HTTP method (or is a GET that only passes an
 // AbortSignal). Without this, fetch defaults to GET and mutating endpoints are

internal/gateway/ui_plugin_test.go

@@ -0,0 +1,390 @@
+package gateway
+
+import (
+	"strings"
+	"testing"
+)
+
+// The plugin UI injection is JavaScript inside the embedded index.html, and it
+// is the ONLY thing that turns a plugin's `ui` block into a visible page or
+// element. These tests pin the wiring on the JS side; the server side (what the
+// payload contains) is covered by TestUIInjectServesPluginUI and the lua
+// package's TestBillingPluginDeclaresUI.
+//
+// What makes this worth pinning: a missing hook here fails SILENTLY. The page
+// simply never appears, there is no error anywhere, and it looks like "the
+// plugin didn't declare a page" rather than "the UI forgot to inject it".
+
+// uiSource returns the embedded WebUI document.
+func uiSourceX(t *testing.T) string {
+	t.Helper()
+	return uiSource(t)
+}
+
+// TestUIFetchesPluginInjection: the boot sequence must ask the kernel what to
+// inject. Without this fetch the whole feature is inert.
+func TestUIFetchesPluginInjection(t *testing.T) {
+	src := uiSourceX(t)
+	if !strings.Contains(src, "/api/ui-inject") {
+		t.Error("the WebUI never calls /api/ui-inject; plugin pages and elements can never appear")
+	}
+}
+
+// TestUIInjectsBeforeFirstRender: injection must be awaited before the first
+// refresh, otherwise the sidebar is built without the plugin entry and the
+// first paint races the fetch. This is an ordering contract, so it is asserted
+// on the source order rather than trusted.
+func TestUIInjectsBeforeFirstRender(t *testing.T) {
+	src := uiSourceX(t)
+	iInject := strings.Index(src, "injectPluginUI()")
+	iRefresh := strings.LastIndex(src, `refresh("status")`)
+	if iInject < 0 {
+		t.Fatal("injectPluginUI() is never called")
+	}
+	if iRefresh < 0 {
+		t.Fatal("the boot sequence no longer calls refresh(\"status\")")
+	}
+	if iInject > iRefresh {
+		t.Error("injectPluginUI() is called after the first refresh; the sidebar " +
+			"and #main would be built before the plugin page exists")
+	}
+	// And it must be awaited, not fire-and-forget.
+	window := src[iInject:]
+	if !strings.Contains(window[:200], ".finally") && !strings.Contains(window[:200], "await") {
+		t.Error("injectPluginUI() is not awaited before refresh; a slow response " +
+			"would race the first paint")
+	}
+}
+
+// TestUIPluginScriptsRunAfterMarkup is the subtle one. Setting innerHTML with a
+// <script> tag does NOT execute it; appending via a template neither does. The
+// mount therefore has to be inserted first and its scripts re-created
+// afterwards, or a plugin's script runs before its own DOM exists — which is
+// exactly the "document.getElementById returns null" failure mode.
+func TestUIPluginScriptsRunAfterMarkup(t *testing.T) {
+	src := uiSourceX(t)
+	// A <template> is used to parse the mount without executing scripts...
+	if !strings.Contains(src, "createElement(\"template\")") {
+		t.Error("the mount is not parsed via <template>; scripts could execute before their DOM")
+	}
+	// ...and scripts are then re-created as fresh elements so they DO run.
+	if !strings.Contains(src, "document.createElement(\"script\")") {
+		t.Error("plugin <script> blocks are never re-created, so they never execute")
+	}
+	if !strings.Contains(src, "replaceWith(s)") {
+		t.Error("the original inert <script> is not replaced by an executable one")
+	}
+}
+
+// TestUIPluginAPISurface: the documented browser API must exist with the exact
+// names docs/plugins.md promises, since plugin authors code against it.
+func TestUIPluginAPISurface(t *testing.T) {
+	src := uiSourceX(t)
+	for _, member := range []string{"fetchState", "postState", "onTabShown"} {
+		if !strings.Contains(src, member+":") && !strings.Contains(src, member+"(") {
+			t.Errorf("window.pluginAPI.%s is missing; docs/plugins.md documents it", member)
+		}
+	}
+}
+
+// TestUIPluginPageBecomesRealTab: a plugin page must get a pane in #main AND a
+// sidebar button wired to goTab, otherwise the page is unreachable.
+func TestUIPluginPageBecomesRealTab(t *testing.T) {
+	src := uiSourceX(t)
+	// pane in #main
+	if !strings.Contains(src, `pane.id = "tab-" + id`) {
+		t.Error("no pane is created for a plugin page")
+	}
+	if !strings.Contains(src, "main.appendChild(pane)") {
+		t.Error("the plugin pane is not appended to #main")
+	}
+	// sidebar button wired to the tab router
+	if !strings.Contains(src, "btn.dataset.tab = id") {
+		t.Error("the sidebar button is not given a data-tab, so goTab() will not route to it")
+	}
+	if !strings.Contains(src, "btn.onclick = () => goTab(id)") {
+		t.Error("the sidebar button is not wired to goTab()")
+	}
+	// and the router must know about it
+	if !strings.Contains(src, "PLUGIN_PAGES.has(tab)") {
+		t.Error("refresh() does not route plugin pages, so opening one renders nothing")
+	}
+}
+
+// TestUIPluginElementsHonorAnchor: elements declare top / bottom / before:sel /
+// after:sel. Silently ignoring the anchor would put a "top" tile at the bottom
+// of the status page, which looks like a layout bug rather than a plugin bug.
+func TestUIPluginElementsHonorAnchor(t *testing.T) {
+	src := uiSourceX(t)
+	for _, anchor := range []string{`anchor === "top"`, `anchor.startsWith("before:")`, `"after:"`} {
+		if !strings.Contains(src, anchor) {
+			t.Errorf("the anchor form %s is not handled; elements would all land at the bottom", anchor)
+		}
+	}
+}
+
+// TestUIPluginInjectionFailureIsNonFatal: plugins are optional, so a failed
+// /api/ui-inject must still leave a working UI (the dashboard has to render).
+// Two places have to cooperate: the function swallows the fetch error, and the
+// caller catches anything that still escapes so refresh() always runs.
+func TestUIPluginInjectionFailureIsNonFatal(t *testing.T) {
+	src := uiSourceX(t)
+	// inside the function: the fetch is wrapped in try/catch
+	fnStart := strings.Index(src, "async function injectPluginUI()")
+	if fnStart < 0 {
+		t.Fatal("injectPluginUI() is not defined")
+	}
+	fn := src[fnStart:]
+	if !strings.Contains(fn, "plugins are optional; the UI must work without them") {
+		t.Error("injectPluginUI does not guard its own fetch failure")
+	}
+	// at the call site: the rejection cannot escape before the first render
+	// LastIndex, not Index: the DEFINITION of injectPluginUI also matches, and
+	// the definition has no .catch on it.
+	iCall := strings.LastIndex(src, "injectPluginUI()")
+	if iCall < 0 {
+		t.Fatal("injectPluginUI() is never called")
+	}
+	// Bound the window at len(src): the call site sits near EOF and a fixed
+	// slice overruns it (a panic in a test is worse than a skipped assertion).
+	end := iCall + 220
+	if end > len(src) {
+		end = len(src)
+	}
+	if !strings.Contains(src[iCall:end], ".catch") {
+		t.Error("a failed /api/ui-inject would reject before refresh(\"status\"), " +
+			"leaving the dashboard blank")
+	}
+}
+
+// ---- plugin management UI contract ---------------------------------------
+//
+// The management page is the operator's only way to take a broken plugin out
+// of the request path. Every one of these assertions guards a link that, if it
+// silently broke, would leave the gateway running with a plugin it cannot
+// disable — the worst kind of gap: everything looks fine and nothing is
+// reachable.
+
+func TestUIHasPluginTabAndPane(t *testing.T) {
+	src := uiSourceX(t)
+	if !strings.Contains(src, `data-tab="plugins"`) {
+		t.Error("no sidebar entry for the plugin page")
+	}
+	if !strings.Contains(src, `id="tab-plugins"`) {
+		t.Error("no #tab-plugins pane")
+	}
+	// The tab list is now a single constant; a new tab must be added there or
+	// goTab will not un-hide its pane.
+	if !strings.Contains(src, `const TABS = [`) {
+		t.Error("TABS is gone; the tab list went back to a duplicated literal")
+	}
+	for _, tn := range []string{"status", "chat", "keys", "sort", "sources", "adapters", "plugins"} {
+		if !strings.Contains(src, `"`+tn+`"`) {
+			t.Errorf("TABS is missing %q", tn)
+		}
+	}
+	// goTab must iterate TABS, not its own list.
+	if !strings.Contains(src, "TABS.forEach((tn) =>") {
+		t.Error("goTab does not iterate TABS")
+	}
+	if strings.Contains(src, `["status", "chat", "keys", "sort", "sources", "adapters"].forEach`) {
+		t.Error("a duplicated tab literal survived; it will drift from TABS")
+	}
+}
+
+func TestUIRendersPluginManagement(t *testing.T) {
+	src := uiSourceX(t)
+	body, ok := jsFunctionBody(src, "renderPlugins")
+	if !ok {
+		t.Fatal("renderPlugins() not found")
+	}
+	// It must read the DISK listing, not just the loaded set: a plugin that
+	// failed to compile is absent from the loaded set, and showing only the
+	// loaded set makes a syntax error look like "the plugin is not installed".
+	if !strings.Contains(body, "on_disk") {
+		t.Error("renderPlugins reads only the loaded set; a failed plugin would " +
+			"be invisible instead of shown with its error")
+	}
+	if !strings.Contains(body, "/api/plugins") {
+		t.Error("renderPlugins does not call /api/plugins")
+	}
+	// Hook errors must be surfaced: a plugin that throws in every stage leaves
+	// no other trace, so without this the symptom is "the feature just doesn't
+	// work".
+	if !strings.Contains(body, "hook_errors") {
+		t.Error("renderPlugins ignores hook_errors; a silently broken plugin is undebuggable")
+	}
+	// Enable / disable / remove / edit.
+	for _, fn := range []string{"togglePlugin", "delPlugin", "installPlugin", "editPlugin"} {
+		if _, ok := jsFunctionBody(src, fn); !ok {
+			t.Errorf("%s() is missing from the WebUI", fn)
+		}
+	}
+	// The toggle must go through the enable/disable endpoint, not delete.
+	tb, ok := jsFunctionBody(src, "togglePlugin")
+	if !ok {
+		t.Fatal("togglePlugin() missing")
+	}
+	if !strings.Contains(tb, `method: "PUT"`) {
+		t.Error("togglePlugin does not use PUT")
+	}
+	if !strings.Contains(tb, "enabled:") {
+		t.Error("togglePlugin does not send an \"enabled\" field")
+	}
+	// And the admin-only tab list must include plugins, or a non-admin would
+	// see a page whose every action 403s.
+	if !strings.Contains(src, `["sort", "sources", "adapters", "plugins"]`) {
+		t.Error("the admin-only tab list omits \"plugins\"; a user key would see a " +
+			"page full of actions that all fail with 403")
+	}
+}
+
+// TestUIBindDropzoneIsParameterised guards the refactor: the adapter and plugin
+// upload forms share one dropzone, so a hard-coded id would send a dropped
+// plugin file into the adapter name field.
+func TestUIBindDropzoneIsParameterised(t *testing.T) {
+	src := uiSourceX(t)
+	body, ok := jsFunctionBody(src, "bindDropzone")
+	if !ok {
+		t.Fatal("bindDropzone() not found")
+	}
+	if strings.Contains(body, `$("#dz")`) || strings.Contains(body, `$("#adp-name")`) {
+		t.Error("bindDropzone still hard-codes the adapter's element ids; the " +
+			"plugin form would write into the adapter form")
+	}
+	if !strings.Contains(body, "dzId") || !strings.Contains(body, "nameSel") {
+		t.Error("bindDropzone does not accept the ids to bind")
+	}
+	// Both forms must call it.
+	if !strings.Contains(src, `bindDropzone("pl-dz", "pl-file", "#pl-name", "#pl-code")`) {
+		t.Error("the plugin upload form does not use the parameterised dropzone")
+	}
+}
+
+// TestPluginElementsSurviveHostRebuild guards the defect that made plugin
+// elements look absent no matter how the injection was configured.
+//
+// renderStatus (and six other pages) assign pane.innerHTML wholesale. Anything a
+// plugin had mounted into that pane is destroyed by the assignment. The symptom
+// is silent and misleading: the plugin really did declare an element, the
+// payload really did arrive, and the element is still gone on the next repaint —
+// so the natural conclusion is "my plugin declared nothing", which sends you
+// looking in the wrong file.
+//
+// The fix is to re-mount after the rebuild. This test asserts the re-mount is
+// wired at the SINGLE place every renderer passes through, rather than leaving
+// it to be re-added per page.
+func TestPluginElementsSurviveHostRebuild(t *testing.T) {
+	html := uiSource(t)
+
+	if !strings.Contains(html, "function remountPluginElements") {
+		t.Fatal("remountPluginElements is not defined; nothing can re-attach a plugin element after a host rebuild")
+	}
+	if !strings.Contains(html, "const PLUGIN_MOUNT_HOOKS = []") {
+		t.Fatal("PLUGIN_MOUNT_HOOKS is not declared")
+	}
+	// The hook array must be declared BEFORE injectPluginUI pushes to it, and
+	// before refresh() calls into it. A use-before-declaration in a const
+	// block is a hard TDZ ReferenceError at first paint.
+	hookDecl := strings.Index(html, "const PLUGIN_MOUNT_HOOKS = []")
+	push := strings.Index(html, "PLUGIN_MOUNT_HOOKS.push")
+	use := strings.Index(html, "PLUGIN_MOUNT_HOOKS.forEach")
+	if hookDecl < 0 || push < 0 || use < 0 {
+		t.Fatal("the hook array is declared but never both filled and drained")
+	}
+	if hookDecl > push || hookDecl > use {
+		t.Error("PLUGIN_MOUNT_HOOKS is used before its declaration (const TDZ: first paint would throw)")
+	}
+
+	// refresh() is the chokepoint every renderer passes through.
+	rf := strings.Index(html, "function refresh(tab)")
+	if rf < 0 {
+		t.Fatal("refresh(tab) is gone")
+	}
+	body := html[rf:]
+	if i := strings.Index(body, "\n      }"); i > 0 {
+		body = body[:i]
+	}
+	if !strings.Contains(body, "remountPluginElements") {
+		t.Error("refresh() does not re-mount plugin elements: a page that rebuilds its DOM wipes them")
+	}
+
+	// A mount must be idempotent, or the widget's <script> runs again on every
+	// host repaint and its counters silently double.
+	if !strings.Contains(html, `data-idx="`) || !strings.Contains(html, "plugin-el[data-idx=") {
+		t.Error("element mounting is not guarded by a per-pane marker; re-mounting would re-run plugin scripts")
+	}
+}
+
+// TestPluginPagesAreReachableByGoTab guards a bug that only shows up in a
+// browser: goTab() iterated the hardcoded TABS list to toggle `hidden`, and a
+// plugin-contributed page is not in that list. The pane existed, the plugin had
+// filled it with real data, and clicking the sidebar entry changed nothing —
+// the `hidden` class was never removed.
+//
+// It reads exactly like "the page is blank" while the content sits in the DOM,
+// and no static check catches it: the injection is correct, the data is correct,
+// and the API returns 200.
+//
+// So this asserts the two structural facts that make it reachable: goTab
+// consults the plugin page set, and that set is declared before goTab runs (a
+// `const` further down the file would be a temporal-dead-zone ReferenceError on
+// the first click).
+func TestPluginPagesAreReachableByGoTab(t *testing.T) {
+	ui := uiSource(t)
+
+	goTab := strings.Index(ui, "function goTab(")
+	if goTab < 0 {
+		t.Fatal("goTab() is gone")
+	}
+	end := strings.Index(ui[goTab:], "\n      }")
+	if end < 0 {
+		t.Fatal("could not isolate goTab()")
+	}
+	body := ui[goTab : goTab+end]
+
+	if !strings.Contains(body, "PLUGIN_PAGES.forEach") {
+		t.Error("★ goTab() does not toggle plugin pages — a plugin page keeps its " +
+			"`hidden` class forever, so the sidebar entry does nothing")
+	}
+
+	// Declaration must precede the use, or the first click throws.
+	decl := strings.Index(ui, "var PLUGIN_PAGES = new Set()")
+	if decl < 0 {
+		// A const later in the file would also "work" only if nothing reads it
+		// first — make that explicit rather than silent.
+		if strings.Contains(ui, "const PLUGIN_PAGES = new Set()") {
+			t.Error("PLUGIN_PAGES is a `const` declared after goTab() reads it — " +
+				"temporal dead zone: the first click on a plugin page throws")
+		} else {
+			t.Error("PLUGIN_PAGES is not declared anywhere")
+		}
+		return
+	}
+	if decl > goTab {
+		t.Errorf("PLUGIN_PAGES is declared at %d but goTab() at %d reads it — "+
+			"declaration must come first", decl, goTab)
+	}
+}
+
+// TestPluginSidebarEntryCarriesATitle: a plugin tab must render icon AND label.
+//
+// Native tabs are `<svg>…</svg><span data-i="navStatus">状态</span>`; the plugin
+// branch set innerHTML to the icon alone, so every plugin page showed up as a
+// nameless icon in the sidebar. An operator cannot tell what an icon means
+// until they click it.
+func TestPluginSidebarEntryCarriesATitle(t *testing.T) {
+	html := uiSource(t)
+	anchor := "btn.innerHTML =\n              pluginIconHTML(pg.icon) +"
+	i := strings.Index(html, anchor)
+	if i < 0 {
+		t.Fatal("plugin sidebar button construction not found")
+	}
+	// Look at the statement the anchor opens, not the whole file.
+	stmt := html[i : i+400]
+	if strings.Contains(stmt, "esc(pg.title") {
+		return
+	}
+	t.Errorf("plugin sidebar button renders the icon only; a label is required. "+
+		"got: %.200s", stmt)
+}

internal/lua/adapters/gemini.lua

@@ -2,7 +2,22 @@ local adapter = {}
 
 adapter.name = "gemini"
 adapter.version = "2.0.0"
-adapter.endpoint = "/v1/models"
+-- The Go layer builds the request URL as base_url + endpoint, statically
+-- (see provider.URL). Gemini's real API is POST
+-- /v1beta/models/{model}:generateContent, and streaming is the same path with
+-- a ":streamGenerateContent" verb -- the model name is part of the PATH, so it
+-- cannot live in a static endpoint string.
+--
+-- "{model}" is therefore a placeholder the Go layer substitutes with the model
+-- this request actually sends (provider.urlFor substitutes it; see
+-- provider.go). Streaming additionally rewrites the ":generateContent" verb to
+-- ":streamGenerateContent" on the same template.
+--
+-- Leaving this as a bare "/v1/models" would call Gemini's model-LIST endpoint,
+-- which answers 405 to POST -- so the preset template would create a source that
+-- can never work. A source that overrides `endpoint:` bypasses the template
+-- entirely and must then spell the whole path itself.
+adapter.endpoint = "/v1beta/models/{model}:generateContent"
 adapter.headers = {}
 
 -- Gemini API: POST /v1/models/{model}:generateContent

internal/lua/billing_period_test.go

@@ -0,0 +1,351 @@
+package lua
+
+import (
+	"encoding/json"
+	"os/exec"
+	"strings"
+	"testing"
+)
+
+// runBillingPage executes the billing page's mount script under node against a
+// DOM stub, drives the period selector, and returns what ended up on screen.
+//
+// It asserts against RENDERED output rather than the plugin's internal
+// helpers. Reaching into the IIFE for daysInWindow/rescale needs a test-only
+// hook in the plugin, and the first version of this file took a long detour
+// through such a hook: the harness's fake `Date` broke toISOString(), the
+// plugin script aborted before assigning the hook, and every assertion
+// compared "" against a real value. The rendered tables are the contract that
+// actually matters, they need no hook, and they cannot pass if the rescale is
+// wrong — which is exactly the bug class under test.
+func runBillingPage(t *testing.T, todayISO, period, captureID string) string {
+	t.Helper()
+	node, err := exec.LookPath("node")
+	if err != nil {
+		t.Skipf("node not available (%v)", err)
+	}
+	page, _ := billingUI(t)
+	js := strings.Join(extractScripts(page), "\n")
+	if !strings.Contains(js, "__billing_setPeriod") {
+		t.Fatal("billing page exposes no period selector")
+	}
+
+	harness := `
+global.window = global;
+global.__written = [];
+global.__errors = [];
+var __realErr = console.error;
+console.error = function () {
+  global.__errors.push("console.error: " + Array.prototype.map.call(arguments, function (a) {
+    return (a && a.message) ? a.message : String(a);
+  }).join(" "));
+  __realErr.apply(console, arguments);
+};
+process.on("uncaughtException", function (e) { global.__errors.push("uncaught: " + String(e && e.message || e)); });
+process.on("unhandledRejection", function (e) { global.__errors.push("unhandled: " + String(e && e.message || e)); });
+
+// Pin "now" for the window under test.
+//
+// Two earlier attempts were wrong here, and both looked like product bugs:
+// replacing the Date constructor wholesale breaks toISOString/UTC; and
+// subclassing (setting __FakeDate.prototype = __RealDate.prototype while
+// returning __RealDate instances) leaves instances WITHOUT a working
+// getUTCDay, so the week window came out NaN and every rendered day became
+// "Invalid time value". A Proxy over the real constructor intercepts only the
+// zero-argument call and leaves instances — and therefore every prototype
+// method — completely untouched.
+var __NOW_MS = new Date("` + todayISO + `T12:34:56Z").getTime();
+var __RealDate = global.Date;
+var __PatchedDate = new Proxy(__RealDate, {
+  construct: function (target, args) {
+    // Reflect.construct, not a hand-spelled argument list: writing
+    // new target(a, b, c, d, e, f, g) passes seven explicit undefineds for a
+    // one-argument call, which Date reads as year..millisecond fields and turns
+    // into an Invalid Date. The symptom was a week window rendering
+    // "Invalid time value" for every day — a harness fault indistinguishable
+    // from a product bug.
+    if (args.length === 0) return Reflect.construct(target, [__NOW_MS]);
+    return Reflect.construct(target, args);
+  },
+  apply: function () { return new __RealDate(__NOW_MS); }
+});
+__PatchedDate.now = function () { return __NOW_MS; };
+__PatchedDate.UTC = __RealDate.UTC;
+__PatchedDate.parse = __RealDate.parse;
+__PatchedDate.prototype = __RealDate.prototype;
+global.Date = __PatchedDate;
+
+global.document = {
+  getElementById: function (id) {
+    if (!global.__els) global.__els = {};
+    if (!global.__els[id]) global.__els[id] = {
+      style: {}, dataset: {}, classList: { add: function(){}, remove: function(){} },
+      options: [{value:"day"},{value:"week"},{value:"month"},{value:"all"}],
+      set innerHTML(v) { if (v && String(v).trim()) global.__written.push(id); this.__h = v; },
+      get innerHTML() { return this.__h || ""; },
+      set textContent(v) { if (v !== undefined && String(v).trim()) global.__written.push(id); this.__t = v; },
+      get textContent() { return this.__t || ""; },
+      set innerText(v) { if (v !== undefined && String(v).trim()) global.__written.push(id); this.__i = v; },
+      get innerText() { return this.__i || ""; },
+      appendChild: function(){}, querySelector: function(){ return null; },
+      querySelectorAll: function(){ return []; }, addEventListener: function(){}
+    };
+    return global.__els[id];
+  },
+  createElement: function () { return { style: {}, dataset: {}, appendChild: function(){}, setAttribute: function(){} }; },
+  addEventListener: function () {},
+};
+
+// Fixture days carry deliberately distinctive costs so a fold over the wrong
+// subset still produces a number, and only a mismatch shows it. 2026-01-05/06/07
+// are Monday/Tuesday/Wednesday; 2025-12-01 is far outside any window here.
+global.__st = {
+  currency: "USD",
+  total: { cost: 999, requests: 999, prompt_tokens: 999999 },
+  by_source: { LIFETIMESRC: { cost: 999, requests: 999 } },
+  by_model: { LIFETIMEMODEL: { cost: 999, requests: 999 } },
+  by_key: { LIFETIMEKEY: { cost: 999, requests: 999 } },
+  by_day: {
+    "2026-01-05": { cost: 10, requests: 1, prompt_tokens: 100, completion_tokens: 10, failures: 0 },
+    "2026-01-06": { cost: 20, requests: 2, prompt_tokens: 200, completion_tokens: 20, failures: 1 },
+    "2026-01-07": { cost: 30, requests: 3, prompt_tokens: 300, completion_tokens: 30, failures: 0 },
+    "2025-12-01": { cost: 777, requests: 77, prompt_tokens: 7700 }
+  },
+  by_day_src: {
+    "2026-01-05": { srcA: { cost: 10, requests: 1 } },
+    "2026-01-06": { srcA: { cost: 20, requests: 2 }, srcB: { cost: 5, requests: 1 } },
+    "2026-01-07": { srcA: { cost: 30, requests: 3 } },
+    "2025-12-01": { srcOLD: { cost: 777, requests: 77 } }
+  },
+  by_day_model: {
+    "2026-01-05": { mA: { cost: 10, requests: 1 } },
+    "2026-01-06": { mA: { cost: 20, requests: 2 } },
+    "2026-01-07": { mA: { cost: 30, requests: 3 } }
+  },
+  by_day_key: {
+    "2026-01-05": { kA: { cost: 10, requests: 1 } },
+    "2026-01-06": { kA: { cost: 20, requests: 2 } },
+    "2026-01-07": { kA: { cost: 30, requests: 3 } }
+  },
+  degraded_reqs: 4242, unpriced_reqs: 77
+};
+global.fetch = function () {
+  return Promise.resolve({ ok: true, json: function () {
+    return Promise.resolve({ plugin: "billing", state: global.__st });
+  }});
+};
+global.pluginAPI = { onTabShown: function () {}, lang: "en" };
+`
+	script := harness + "\n" + js + "\n" +
+		"__billing_setPeriod(" + jsonStr(period) + ");\n" +
+		// Let the period-triggered refresh() settle before reading the DOM.
+		"setTimeout(function () {\n" +
+		"  var el = document.getElementById(" + jsonStr(captureID) + ");\n" +
+		"  console.log('__CAPTURE__' + JSON.stringify({\n" +
+		"    html: el ? String(el.innerHTML) : '(missing)',\n" +
+		"    kpis: String(document.getElementById('billing-kpis').innerHTML),\n" +
+		"    sel: String(document.getElementById('billing-period').value),\n" +
+		"    errors: global.__errors\n" +
+		"  }));\n" +
+		"}, 60);\n"
+
+	cmd := exec.Command(node, "-e", script)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("node execution failed: %v\n%s", err, out)
+	}
+	o := string(out)
+	idx := strings.Index(o, "__CAPTURE__")
+	if idx < 0 {
+		t.Fatalf("no capture in node output (the plugin script aborted?):\n%s", o)
+	}
+	raw := strings.TrimSpace(o[idx+len("__CAPTURE__"):])
+	if nl := strings.IndexAny(raw, "\r\n"); nl >= 0 {
+		raw = raw[:nl]
+	}
+	var got struct {
+		HTML   string   `json:"html"`
+		KPIs   string   `json:"kpis"`
+		Sel    string   `json:"sel"`
+		Errors []string `json:"errors"`
+	}
+	if err := json.Unmarshal([]byte(raw), &got); err != nil {
+		t.Fatalf("capture is not JSON: %v\n%s", err, raw)
+	}
+	if len(got.Errors) > 0 {
+		t.Fatalf("billing script reported errors: %v", got.Errors)
+	}
+	if got.Sel != period {
+		t.Errorf("selector shows %q after setting %q — the change handler did not take", got.Sel, period)
+	}
+	return got.HTML + "\n@@KPI@@\n" + got.KPIs
+}
+
+func jsonStr(s string) string {
+	b, _ := json.Marshal(s)
+	return string(b)
+}
+
+// TestBillingPeriodDayShowsOnlyThatDay checks the one-day window end to end:
+// the tables must carry that day's rows and drop every other day, and the
+// lifetime sentinel (999 / LIFETIMESRC) must appear nowhere.
+func TestBillingPeriodDayShowsOnlyThatDay(t *testing.T) {
+	got := runBillingPage(t, "2026-01-07", "day", "billing-by-source")
+	if strings.Contains(got, "LIFETIME") || strings.Contains(got, "999") {
+		t.Errorf("a one-day view still shows lifetime figures:\n%s", got)
+	}
+	if strings.Contains(got, "srcB") {
+		t.Errorf("a one-day view shows srcB, which only had traffic on 01-06:\n%s", got)
+	}
+	if strings.Contains(got, "srcOLD") {
+		t.Errorf("a one-day view shows a day from 2025-12:\n%s", got)
+	}
+	if !strings.Contains(got, "srcA") {
+		t.Errorf("a one-day view lost the only source that had traffic that day:\n%s", got)
+	}
+	// The KPI total must be that day's cost (30), not the week (60) and not
+	// the lifetime sentinel (999).
+	if !strings.Contains(got, "30") {
+		t.Errorf("KPI does not show the day's cost 30:\n%s", got)
+	}
+}
+
+// TestBillingPeriodWeekSumsThreeDays is the arithmetic: Mon+Wed rows and a
+// total of 60. A window that started on Sunday or ended early still renders
+// tables, so only the number distinguishes it.
+func TestBillingPeriodWeekSumsThreeDays(t *testing.T) {
+	// 2026-01-07 is a Wednesday: the ISO week holds 01-05, 01-06, 01-07.
+	got := runBillingPage(t, "2026-01-07", "week", "billing-by-source")
+	if strings.Contains(got, "srcOLD") || strings.Contains(got, "LIFETIME") {
+		t.Errorf("weekly view leaks out-of-window or lifetime rows:\n%s", got)
+	}
+	// srcA = 10+20+30 = 60, srcB = 5 (only 01-06, but inside the week).
+	if !strings.Contains(got, "60") {
+		t.Errorf("weekly total should be 60, got:\n%s", got)
+	}
+	if !strings.Contains(got, "srcB") {
+		t.Errorf("weekly view dropped srcB, whose only day (01-06) is in the window:\n%s", got)
+	}
+}
+
+// TestBillingPeriodSundayReachesBackToMonday pins the ISO-week Monday rule
+// from the other side. On Sunday 2026-01-11 the week that already ended is
+// Mon 05..Sun 11, so all three fixture days are in it; a start-on-Sunday bug
+// would still include 01-07 and pass, so this case is paired with the
+// weekday case above rather than relied on alone.
+func TestBillingPeriodSundayReachesBackToMonday(t *testing.T) {
+	got := runBillingPage(t, "2026-01-11", "week", "billing-by-source")
+	if !strings.Contains(got, "60") {
+		t.Errorf("Sunday's week view should still total 60:\n%s", got)
+	}
+	// And the Monday view must NOT include Sunday's (nonexistent) traffic.
+	gotMon := runBillingPage(t, "2026-01-05", "day", "billing-by-source")
+	if strings.Contains(gotMon, "30") {
+		t.Errorf("Monday's single day view shows Wednesday's cost 30:\n%s", gotMon)
+	}
+	if !strings.Contains(gotMon, "10") {
+		t.Errorf("Monday's day view lost Monday's own cost 10:\n%s", gotMon)
+	}
+}
+
+// TestBillingPeriodKpiTotalMatchesWindowDays pins the KPI total itself.
+//
+// The dimension-table tests above cannot catch a broken window or a broken
+// fold: by_source is computed from the per-day DIMENSION map, independently of
+// the total. Mutation verification proved it — disabling the total fold, and
+// shifting the ISO-week start to Sunday, both left every earlier test green.
+// The total is derived from by_day, so it is the one value that moves when
+// either the window membership or the accumulation is wrong.
+func TestBillingPeriodKpiTotalMatchesWindowDays(t *testing.T) {
+	kpis := func(t *testing.T, today, period string) string {
+		t.Helper()
+		return runBillingPage(t, today, period, "billing-by-source")
+	}
+	// 2026-01-07 is a Wednesday; fixture days are 05(10) 06(20) 07(30).
+	// KPI renders through fmtInt, so 30 -> "30", 60 -> "60".
+	if got := kpis(t, "2026-01-07", "day"); !strings.Contains(got, "30") {
+		t.Errorf("day KPI should show that day's cost 30:\n%s", got)
+	}
+	if got := kpis(t, "2026-01-07", "week"); !strings.Contains(got, "60") {
+		t.Errorf("week KPI should total 10+20+30 = 60:\n%s", got)
+	}
+	// Sunday 2026-01-11: the ISO week Mon 05..Sun 11 still holds all three days.
+	if got := kpis(t, "2026-01-11", "week"); !strings.Contains(got, "60") {
+		t.Errorf("Sunday's week KPI should still total 60:\n%s", got)
+	}
+	// The Monday rule from the negative side. A window that started on SUNDAY
+	// would cover Sun 11..Sat 17 and contain none of the fixture days, giving
+	// a total of 0 — so this case is what makes the +6 shift observable. The
+	// positive case alone cannot distinguish it: shifting the start one day
+	// later still happens to contain 01-07.
+	if got := kpis(t, "2026-01-11", "day"); !strings.Contains(got, "0") {
+		t.Errorf("Sunday's single-day window has no fixture traffic and must total 0:\n%s", got)
+	}
+	// Monday 2026-01-12 begins a new week; it contains no fixture days.
+	if got := kpis(t, "2026-01-12", "week"); !strings.Contains(got, "0") {
+		t.Errorf("an empty week should report 0, not stale data:\n%s", got)
+	}
+	// ...whereas the Monday-to-Sunday week that just ended does.
+	if got := kpis(t, "2026-01-12", "day"); !strings.Contains(got, "0") {
+		t.Errorf("Monday the 12th has no fixture traffic and must total 0:\n%s", got)
+	}
+}
+
+// TestBillingPeriodDimensionFoldSumsAcrossDays covers the per-dimension
+// accumulation. Asserting "60 appears somewhere" was NOT enough: mutation
+// verification showed a fold that keeps only the last day still passed,
+// because 60 also appears in the KPI total and in a token column. The
+// assertion must therefore pin srcA's own cost cell, not the page's text.
+func TestBillingPeriodDimensionFoldSumsAcrossDays(t *testing.T) {
+	got := runBillingPage(t, "2026-01-07", "week", "billing-by-source")
+	// srcA exists on all three days at 10/20/30. Summed = 60; last-only = 30.
+	if !strings.Contains(got, "USD 60.0000") {
+		t.Errorf("weekly by-source did not sum srcA across days (want USD 60.0000, "+
+			"last-day-only would be USD 30.0000):\n%s", got)
+	}
+	// srcB exists only on 01-06 at 5, inside the window, so it must survive at
+	// exactly its own value.
+	if !strings.Contains(got, "USD 5.0000") {
+		t.Errorf("weekly by-source lost or altered srcB (want USD 5.0000):\n%s", got)
+	}
+	// srcA's summed cost must also differ from its last-day value in the
+	// rendered table, so an overwrite cannot masquerade as a sum.
+	if strings.Count(got, "USD 60.0000") < 2 {
+		t.Errorf("expected the summed 60 in both the table and the KPI:\n%s", got)
+	}
+}
+
+// state untouched, including the lifetime sentinel and the lifetime-only
+// degraded counter. Without this control, a rescale that silently degraded
+// into "always empty" would pass the narrow-window tests.
+// TestBillingPeriodAllStaysLifetime is the control: "all" must keep the stored
+// state untouched. Without it, a rescale that silently degraded into "always
+// empty" would pass every narrow-window test above.
+func TestBillingPeriodAllStaysLifetime(t *testing.T) {
+	got := runBillingPage(t, "2026-01-07", "all", "billing-by-source")
+	if !strings.Contains(got, "LIFETIMESRC") && !strings.Contains(got, "999") {
+		t.Errorf("the all-time view dropped the lifetime figures:\n%s", got)
+	}
+	// 4242 is the lifetime degraded_reqs; it has no day-keyed tally, so it
+	// must remain visible when the window is "all". The KPI goes through
+	// fmtInt, so it renders grouped ("4,242") — assert the rendered form.
+	if !strings.Contains(got, "4,242") {
+		t.Errorf("the all-time view should still show the lifetime degraded count:\n%s", got)
+	}
+}
+
+// TestBillingPeriodHidesLifetimeOnlyCounters is the mismatch the period view
+// exists to remove: degraded/unpriced have no day-keyed tally, so printing
+// the lifetime number next to a per-window cost is misleading. They must be
+// hidden, not merely relabelled.
+func TestBillingPeriodHidesLifetimeOnlyCounters(t *testing.T) {
+	got := runBillingPage(t, "2026-01-07", "day", "billing-by-source")
+	if strings.Contains(got, "4,242") || strings.Contains(got, "Degraded") {
+		t.Errorf("a one-day view still shows the lifetime degraded counter:\n%s", got)
+	}
+	// ...while "all" does show it (covered above), so this is not just a
+	// dictionary that lost the words.
+	if !strings.Contains(runBillingPage(t, "2026-01-07", "all", "billing-by-source"), "4,242") {
+		t.Error("the all-time view lost the degraded counter — the hide is not period-scoped")
+	}
+}

internal/lua/billing_test.go

@@ -0,0 +1,968 @@
+package lua
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// The billing plugin ships with the gateway, so its arithmetic is a contract:
+// a wrong price silently produces wrong money. These tests drive it through the
+// real hook path and check the NUMBERS, not merely that it loads.
+
+func billingVM(t *testing.T) (*Plugins, string) {
+	t.Helper()
+	dir := filepath.Join(t.TempDir(), "adapters")
+	vm := NewVM(dir)
+	if err := vm.Start(); err != nil {
+		t.Fatalf("vm: %v", err)
+	}
+	t.Cleanup(vm.Stop)
+	pdir := filepath.Join(t.TempDir(), "plugins")
+	ps := NewPlugins(vm, pdir)
+	if err := ps.SeedBundled(); err != nil {
+		t.Fatalf("seed: %v", err)
+	}
+	if err := ps.LoadDir(); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	return ps, pdir
+}
+
+// stateOf reads the plugin's published state as a generic map.
+func stateOf(t *testing.T, ps *Plugins) map[string]interface{} {
+	t.Helper()
+	raw := ps.State("billing")
+	if raw == nil {
+		t.Fatal("billing published no state")
+	}
+	b, err := json.Marshal(raw)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var out map[string]interface{}
+	if err := json.Unmarshal(b, &out); err != nil {
+		t.Fatal(err)
+	}
+	return out
+}
+
+func approx(t *testing.T, name string, got, want float64) {
+	t.Helper()
+	d := got - want
+	if d < 0 {
+		d = -d
+	}
+	if d > 1e-9 {
+		t.Errorf("%s = %v, want %v (delta %v)", name, got, want, d)
+	}
+}
+
+// TestBillingZeroPricesIsSafe: with no configuration the plugin must still run
+// and report volume. A nil-price crash here would take out every request.
+func TestBillingZeroPricesIsSafe(t *testing.T) {
+	ps, _ := billingVM(t)
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "s", "key": "***aaaaaa", "ok": true,
+		"prompt_tokens": 100, "completion_tokens": 50, "time": 1750000000000,
+	})
+	st := stateOf(t, ps)
+	total := st["total"].(map[string]interface{})
+	if total["requests"].(float64) != 1 {
+		t.Errorf("requests = %v, want 1", total["requests"])
+	}
+	approx(t, "cost with no prices", total["cost"].(float64), 0)
+}
+
+// TestBillingModelTokenPricing: the core case. prompt and completion are priced
+// SEPARATELY, which is how providers publish and how the total must come out.
+func TestBillingModelTokenPricing(t *testing.T) {
+	ps, _ := billingVM(t)
+	// Setting prices must NOT disturb the (still empty) totals, which is the
+	// whole point of the prices/state split.
+	if err := ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"currency": "USD",
+			"models": map[string]interface{}{
+				"gpt-5.4": map[string]interface{}{"prompt": 1.25e-6, "completion": 1e-5},
+			},
+		},
+	}); err != nil {
+		t.Fatal(err)
+	}
+	// 1000 prompt * 1.25e-6 = 0.00125 ; 500 completion * 1e-5 = 0.005
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "gpt-5.4", "source": "up", "key": "***aaaaaa", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 500, "time": 1750000000000,
+	})
+	st := stateOf(t, ps)
+	approx(t, "total cost", st["total"].(map[string]interface{})["cost"].(float64), 0.00625)
+	byModel := st["by_model"].(map[string]interface{})["gpt-5.4"].(map[string]interface{})
+	approx(t, "model cost", byModel["cost"].(float64), 0.00625)
+	if byModel["completion_tokens"].(float64) != 500 {
+		t.Errorf("completion_tokens = %v, want 500", byModel["completion_tokens"])
+	}
+}
+
+// TestBillingPerRequestAndTokenCombine: a flat fee is ADDED to the token cost,
+// which is how an image model can be "tokens + fixed fee".
+func TestBillingPerRequestAndTokenCombine(t *testing.T) {
+	ps, _ := billingVM(t)
+	if err := ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"kolors": map[string]interface{}{"prompt": 1e-6, "completion": 2e-6, "per_request": 0.04},
+			},
+		},
+	}); err != nil {
+		t.Fatal(err)
+	}
+	// 100*1e-6 + 50*2e-6 + 0.04 = 0.0402
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "kolors", "source": "sf", "key": "***bbbbbb", "ok": true,
+		"prompt_tokens": 100, "completion_tokens": 50, "time": 1750000000000,
+	})
+	st := stateOf(t, ps)
+	approx(t, "total", st["total"].(map[string]interface{})["cost"].(float64), 0.0402)
+}
+
+// TestBillingPrecedence: keys > models > default for token prices.
+func TestBillingPrecedence(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"default": map[string]interface{}{"prompt": 9e-6, "completion": 9e-6},
+			"models":  map[string]interface{}{"m": map[string]interface{}{"prompt": 2e-6, "completion": 3e-6}},
+			"keys":    map[string]interface{}{"***cccccc": map[string]interface{}{"prompt": 1e-6, "completion": 1.5e-6}},
+		},
+	})
+
+	// No key match -> model price.
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "s", "key": "***other", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 1000, "time": 1750000000000,
+	})
+	// Key match -> key price wins.
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "s", "key": "***cccccc", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 1000, "time": 1750000000000,
+	})
+	st := stateOf(t, ps)
+	// 1000*2e-6 + 1000*3e-6 = 0.005 ; 1000*1e-6 + 1000*1.5e-6 = 0.0025
+	approx(t, "total (model + key)", st["total"].(map[string]interface{})["cost"].(float64), 0.0075)
+
+	// An unpriced model falls back to default.
+	ps2, _ := billingVM(t)
+	_ = ps2.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"default": map[string]interface{}{"prompt": 9e-6, "completion": 9e-6},
+		},
+	})
+	ps2.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "unknown", "source": "s", "key": "***d", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 1000, "time": 1750000000000,
+	})
+	approx(t, "default fallback", stateOf(t, ps2)["total"].(map[string]interface{})["cost"].(float64), 0.018)
+}
+
+// TestBillingAggregatesEveryDimension: one request must land in all four
+// rollups plus the daily bucket. A missing dimension is the kind of bug a
+// dashboard hides (it just renders an empty table).
+func TestBillingAggregatesEveryDimension(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"models": map[string]interface{}{"m1": map[string]interface{}{"prompt": 1e-6, "completion": 1e-6}},
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m1", "source": "srcA", "key": "***key01", "ok": true,
+		"prompt_tokens": 100, "completion_tokens": 100, "time": 1750000000000,
+	})
+	st := stateOf(t, ps)
+	for _, dim := range []string{"by_source", "by_model", "by_key", "by_day"} {
+		m, ok := st[dim].(map[string]interface{})
+		if !ok || len(m) == 0 {
+			t.Errorf("%s is empty; a dimension is missing", dim)
+		}
+	}
+	if _, ok := st["by_source"].(map[string]interface{})["srcA"]; !ok {
+		t.Error("by_source lacks srcA")
+	}
+	if _, ok := st["by_key"].(map[string]interface{})["***key01"]; !ok {
+		t.Error("by_key lacks the gateway key")
+	}
+	// Milliseconds must be converted, not used as seconds: a raw 1750000000000
+	// would land in a year-57000 bucket.
+	days := st["by_day"].(map[string]interface{})
+	found := false
+	for k := range days {
+		if len(k) == 10 && strings.Contains(k, "-") {
+			found = true
+		}
+		if strings.HasPrefix(k, "5") && len(k) > 6 {
+			t.Errorf("by_day key %q suggests millisecond timestamps were not converted", k)
+		}
+	}
+	if !found {
+		t.Errorf("by_day has no YYYY-MM-DD key: %v", days)
+	}
+}
+
+// TestBillingFailedRequestPolicy: a failed request keeps its token cost (tokens
+// really were consumed) but drops the flat per_request fee (never charged).
+func TestBillingFailedRequestPolicy(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"m": map[string]interface{}{"prompt": 1e-6, "completion": 1e-6, "per_request": 0.5},
+			},
+		},
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "s", "key": "***e", "ok": false, "status": 500,
+		"prompt_tokens": 1000, "completion_tokens": 0, "time": 1750000000000,
+	})
+	st := stateOf(t, ps)
+	// 1000*1e-6 = 0.001, flat dropped.
+	approx(t, "failed request", st["total"].(map[string]interface{})["cost"].(float64), 0.001)
+	if st["total"].(map[string]interface{})["failures"].(float64) != 1 {
+		t.Error("failures not counted")
+	}
+}
+
+// TestBillingStateAPIReplace: the admin price update must actually change
+// subsequent pricing (not just be stored).
+func TestBillingStateAPIReplace(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{"m": map[string]interface{}{"prompt": 1e-6, "completion": 0}},
+		},
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "s", "key": "***f", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 0, "time": 1750000000000,
+	})
+	approx(t, "before reprice", stateOf(t, ps)["total"].(map[string]interface{})["cost"].(float64), 0.001)
+
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{"m": map[string]interface{}{"prompt": 2e-6, "completion": 0}},
+		},
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "s", "key": "***f", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 0, "time": 1750000000000,
+	})
+	// 0.001 (old) + 0.002 (new price)
+	approx(t, "after reprice", stateOf(t, ps)["total"].(map[string]interface{})["cost"].(float64), 0.003)
+}
+
+// TestBillingPluginDeclaresUI: the shipped plugin must ship its dashboard, or
+// "billing is enabled" would be true while showing the user nothing.
+func TestBillingPluginDeclaresUI(t *testing.T) {
+	ps, _ := billingVM(t)
+	for _, row := range ps.List() {
+		if row["name"] != "billing" {
+			continue
+		}
+		ui, ok := row["ui"].(map[string]interface{})
+		if !ok {
+			t.Fatal("billing declares no ui")
+		}
+		if page, _ := ui["page"].(string); page != "billing" {
+			t.Errorf("ui.page = %v, want \"billing\"", ui["page"])
+		}
+		// ONE page, not two. The rule editor and the totals share a sidebar
+		// entry because billing is one thing: prices decide the numbers and the
+		// numbers are the result of the prices. Split across two pages, saving a
+		// price left no on-screen way to see its effect — the loop the operator
+		// actually works in was cut in half.
+		pages, _ := ui["pages"].([]string)
+		if len(pages) != 1 || pages[0] != "billing" {
+			t.Errorf("ui.pages = %v, want exactly one page [billing]", pages)
+		}
+		if n, _ := ui["elements"].(int); n < 1 {
+			t.Error("billing contributes no element to an existing page")
+		}
+		return
+	}
+	t.Fatal("billing plugin is not loaded")
+}
+
+// TestBillingRuleEditorLivesInsideTheBillingPage: the rule editor is a VIEW
+// inside the billing page, not a second sidebar entry.
+//
+// This started as a separate page and was wrong: saving a price sent the
+// operator to a different screen to find out whether it worked. A single page
+// with a view switch keeps the loop closed, and the rule editor already refreshes
+// the usage numbers on save, so the effect is visible immediately.
+//
+// The mount must therefore carry BOTH the usage tables and the rule editor, and
+// the switch that toggles between them.
+func TestBillingRuleEditorLivesInsideTheBillingPage(t *testing.T) {
+	ps, _ := billingVM(t)
+	var ui *UIExtension
+	for _, p := range ps.plugins {
+		if p.Info.Name == "billing" {
+			ui = p.UI
+		}
+	}
+	if ui == nil || ui.Page == nil {
+		t.Fatal("billing plugin loaded with no page")
+	}
+	if ui.Page.PageID != "billing" {
+		t.Errorf("page id = %q, want billing", ui.Page.PageID)
+	}
+	mount := ui.Page.Mount
+
+	// Both halves on one page.
+	for _, needle := range []string{`id="billing-kpis"`, `id="billing-by-source"`} {
+		if !strings.Contains(mount, needle) {
+			t.Errorf("the usage half is missing %s", needle)
+		}
+	}
+	for _, needle := range []string{
+		`id="br-body"`,
+		"data-act='save'", "data-act='export'", "data-act='newprofile'",
+		".r-url", ".r-mode",
+	} {
+		if !strings.Contains(mount, needle) {
+			t.Errorf("the rule editor is missing %s", needle)
+		}
+	}
+	// The switch itself, or the two halves are both on screen at once.
+	for _, needle := range []string{`id="billing-view-usage"`, `id="billing-view-rules"`, `window.__billing_view(`} {
+		if !strings.Contains(mount, needle) {
+			t.Errorf("the view switch is missing %s", needle)
+		}
+	}
+	// The rules view must start hidden, otherwise it renders under the usage
+	// tables and the page is a wall of two editors stacked.
+	if !strings.Contains(mount, `id="billing-view-rules" style="display:none;`) {
+		t.Error(`the rules view does not start hidden — both halves would render at once`)
+	}
+	// NO DUPLICATE IDS between the switch buttons and the view containers.
+	// They shipped as billing-view-<name> on BOTH the button and the pane, so
+	// document.getElementById returned the 72px-wide BUTTON for the pane and
+	// every measurement was of the wrong element: the table measured 0 wide and
+	// the page looked broken while the layout was fine. The ids must be unique
+	// and the buttons carry a distinct suffix.
+	for _, id := range []string{`billing-view-usage`, `billing-view-rules`} {
+		if n := strings.Count(mount, `id="`+id+`"`); n != 1 {
+			t.Errorf("id %q appears %d times; getElementById would return the wrong element", id, n)
+		}
+		if !strings.Contains(mount, `id="`+id+`-btn"`) {
+			t.Errorf("switch button for %q is missing its -btn id", id)
+		}
+	}
+	// Both view containers must FILL the pane. The host's tab-pane is a flex
+	// column, so a plain div shrinks to its content: without flex:1/width:100%
+	// the rules view measured 72px wide and its table measured 0 — the page
+	// rendered "nothing" while the DOM was perfectly correct. This is exactly
+	// the class of bug a DOM assertion misses and a screenshot catches.
+	for _, needle := range []string{
+		`id="billing-view-usage" style="flex:1`,
+		`id="billing-view-rules" style="display:none;flex:1`,
+	} {
+		if !strings.Contains(mount, needle) {
+			t.Errorf("view container does not fill the pane: %q missing — "+
+				"a flex item without flex:1 collapses to content width", needle)
+		}
+	}
+}
+
+// TestUIExtensionMergesEveryPluginPage: two plugins contributing pages must
+// BOTH appear. The old merge assigned a single field, so the second plugin
+// erased the first one's page from the sidebar with no error anywhere.
+func TestUIExtensionMergesEveryPluginPage(t *testing.T) {
+	ps, pdir := billingVM(t)
+	mk := func(name, code string) {
+		if err := os.WriteFile(filepath.Join(pdir, name+".lua"), []byte(code), 0644); err != nil {
+			t.Fatal(err)
+		}
+		if err := ps.LoadSource(name, code); err != nil {
+			t.Fatalf("load %s: %v", name, err)
+		}
+	}
+	mk("other", `
+local plugin = {}
+plugin.name = "other"
+plugin.version = "0.1"
+plugin.ui = { page = { page_id = "other-page", title = "Other", order = 90,
+  mount = "<div id='other-root'></div>" } }
+return plugin`)
+	mk("third", `
+local plugin = {}
+plugin.name = "third"
+plugin.version = "0.1"
+plugin.ui = { pages = {
+  { page_id = "third-a", title = "Third A", order = 80, mount = "<div id='ta'></div>" },
+  { page_id = "third-b", title = "Third B", order = 81, mount = "<div id='tb'></div>" },
+} }
+return plugin`)
+
+	ui := ps.UI()
+	if ui == nil {
+		t.Fatal("no merged UI")
+	}
+	got := map[string]bool{}
+	for _, pg := range ui.Pages {
+		got[pg.PageID] = true
+	}
+	// billing contributes exactly one page (the rule editor is a view inside it),
+	// so it is listed once. The multi-page merging is exercised by the three
+	// plugins added here.
+	for _, want := range []string{"billing", "other-page", "third-a", "third-b"} {
+		if !got[want] {
+			t.Errorf("merged UI lost page %q; has %v", want, got)
+		}
+	}
+	// A duplicate page_id must not appear twice. Two plugins claiming the same
+	// id collide in the DOM (getElementById returns the first, the second pane
+	// is silently unreachable), so the merge keeps the first and drops the
+	// later one.
+	mk("collide", `
+local plugin = {}
+plugin.name = "collide"
+plugin.version = "0.1"
+plugin.ui = { pages = {
+  { page_id = "third-a", title = "Impostor", order = 79, mount = "<div id='impostor'></div>" },
+} }
+return plugin`)
+	ui = ps.UI()
+	counts := map[string]int{}
+	for _, pg := range ui.Pages {
+		counts[pg.PageID]++
+	}
+	if counts["third-a"] != 1 {
+		t.Errorf("page id third-a appears %d times; a duplicate id collides in the DOM", counts["third-a"])
+	}
+	for _, pg := range ui.Pages {
+		if pg.PageID == "third-a" && pg.Title == "Impostor" {
+			t.Error("the LATER plugin won the id; first writer should keep it")
+		}
+	}
+
+	// Order must be honoured so the sidebar is predictable.
+	if len(ui.Pages) != 4 {
+		t.Fatalf("expected all 4 pages to merge, got %d: %v", len(ui.Pages), got)
+	}
+	for i := 1; i < len(ui.Pages); i++ {
+		if ui.Pages[i].Order < ui.Pages[i-1].Order {
+			t.Errorf("pages out of order at %d: %d before %d",
+				i, ui.Pages[i-1].Order, ui.Pages[i].Order)
+		}
+	}
+}
+
+// TestBillingPluginLoadedByDefault: the shipped plugin must load with no
+// configuration, since seeding only happens on a fresh plugin dir.
+func TestBillingPluginLoadedByDefault(t *testing.T) {
+	ps, pdir := billingVM(t)
+	if ps.Count() != 1 {
+		t.Fatalf("expected 1 bundled plugin, got %d", ps.Count())
+	}
+	if _, err := os.Stat(filepath.Join(pdir, "billing.lua")); err != nil {
+		t.Errorf("billing.lua was not written to the plugin dir: %v", err)
+	}
+}
+
+// TestBillingCountsDegradations: the plugin must distinguish a request that had
+// to drop below the top tier from one the top tier served. Without the chain
+// trace these were identical in the accounts, so a quietly degraded gateway
+// looked healthy while spending more per request.
+func TestBillingCountsDegradations(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"hi-tier": map[string]interface{}{"prompt": 1e-5, "completion": 1e-5},
+				"lo-tier": map[string]interface{}{"prompt": 1e-6, "completion": 1e-6},
+			},
+		},
+	})
+
+	// Request 1: degraded. tier 1 hard-failed, tier 2 served it.
+	ps.Fire(StageChainStep, map[string]interface{}{
+		"kind": "slot_fail", "tier": 1, "source": "t1", "model": "hi-tier",
+	})
+	ps.Fire(StageChainStep, map[string]interface{}{
+		"kind": "selected", "tier": 2, "source": "t2", "model": "lo-tier",
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "lo-tier", "source": "t2", "key": "***d1", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 1000,
+		"degraded": true, "tier_served": 2, "time": 1750000000000,
+	})
+
+	// Request 2: clean, served by the top tier.
+	ps.Fire(StageChainStep, map[string]interface{}{
+		"kind": "selected", "tier": 1, "source": "t1", "model": "hi-tier",
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "hi-tier", "source": "t1", "key": "***d1", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 1000,
+		"degraded": false, "tier_served": 1, "time": 1750000000000,
+	})
+
+	st := stateOf(t, ps)
+	if got := st["degraded_reqs"].(float64); got != 1 {
+		t.Errorf("degraded_reqs = %v, want 1 (one of the two requests dropped a tier)", got)
+	}
+	tiers := st["by_tier_served"].(map[string]interface{})
+	if tiers["2"].(float64) != 1 {
+		t.Errorf("by_tier_served[2] = %v, want 1", tiers["2"])
+	}
+	if tiers["1"].(float64) != 1 {
+		t.Errorf("by_tier_served[1] = %v, want 1", tiers["1"])
+	}
+	// Cost reflects the model actually served, not the one that should have been.
+	// 1000*1e-6*2 = 0.002 for the degraded one, 1000*1e-5*2 = 0.02 for the clean one.
+	approx(t, "total", st["total"].(map[string]interface{})["cost"].(float64), 0.022)
+}
+
+// TestBillingAggregatesSkipReasons: skip reasons are the actionable diagnostic
+// ("no schedulable slot (cooling or quota exhausted)"), so they must be
+// counted. The wait time is normalised, otherwise a fresh row per request would
+// appear whenever the busy-wait text varies.
+func TestBillingAggregatesSkipReasons(t *testing.T) {
+	ps, _ := billingVM(t)
+	ps.Fire(StageChainStep, map[string]interface{}{
+		"kind": "tier_skip", "tier": 1, "reason": "no schedulable slot (cooling or quota exhausted)",
+	})
+	ps.Fire(StageChainStep, map[string]interface{}{
+		"kind": "tier_busy", "tier": 2, "reason": "no free slot within 2s",
+	})
+	ps.Fire(StageChainStep, map[string]interface{}{
+		"kind": "tier_busy", "tier": 3, "reason": "no free slot within 2.0001s",
+	})
+	st := stateOf(t, ps)
+	reasons := st["skip_reasons"].(map[string]interface{})
+	if len(reasons) != 2 {
+		t.Errorf("skip_reasons = %v, want 2 (the two variable waits must collapse to one)", reasons)
+	}
+	busy, ok := reasons["no free slot within <wait>"]
+	if !ok {
+		t.Errorf("busy reason missing; got %v", reasons)
+	} else if busy.(float64) != 2 {
+		t.Errorf("busy count = %v, want 2 (two different wait texts, one cause)", busy)
+	}
+}
+
+// ---- prompt-cache pricing -------------------------------------------------
+//
+// A cached prompt token is not a fresh one. Charging the full prompt rate made a
+// 1M-token request of which 900k were cache reads cost 10 USD instead of ~1.9
+// — an order of magnitude, on exactly the traffic the cache exists to make
+// cheap. Agent traffic replays long shared prefixes constantly, so this was the
+// single largest source of over-billing in the plugin.
+
+func TestBillingCacheHitsAreDiscounted(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"m": map[string]interface{}{"prompt": 1e-5, "completion": 1e-5},
+			},
+		},
+	})
+	// 1M prompt of which 900k cached, default discount 0.1
+	// 100k fresh * 1e-5 = 1.0 ; 900k cached * 1e-5 * 0.1 = 0.9
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "s", "key": "***c", "ok": true,
+		"prompt_tokens": 1000000, "completion_tokens": 0,
+		"cache_hit_tokens": 900000, "time": 1750000000000,
+	})
+	approx(t, "cache-discounted cost", stateOf(t, ps)["total"].(map[string]interface{})["cost"].(float64), 1.9)
+}
+
+// A per-model discount overrides the global one, because the ratio is a
+// per-provider fact, not a constant.
+func TestBillingCacheDiscountIsPerModel(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"free-cache": map[string]interface{}{
+					"prompt": 1e-5, "completion": 0, "cache_discount": 0,
+				},
+				"flat": map[string]interface{}{
+					"prompt": 1e-5, "completion": 0, "cache_discount": 1,
+				},
+			},
+		},
+	})
+	for _, m := range []string{"free-cache", "flat"} {
+		ps2, _ := billingVM(t)
+		_ = ps2.SetState("billing", map[string]interface{}{
+			"prices": map[string]interface{}{
+				"models": map[string]interface{}{
+					m: map[string]interface{}{"prompt": 1e-5, "completion": 0, "cache_discount": map[bool]float64{true: 0, false: 1}[m == "free-cache"]},
+				},
+			},
+		})
+		ps2.Fire(StageRequestEnd, map[string]interface{}{
+			"model": m, "source": "s", "key": "***c", "ok": true,
+			"prompt_tokens": 1000000, "cache_hit_tokens": 1000000,
+			"time": 1750000000000,
+		})
+		want := 0.0
+		if m == "flat" {
+			want = 10.0
+		}
+		approx(t, m+" (all cached)", stateOf(t, ps2)["total"].(map[string]interface{})["cost"].(float64), want)
+	}
+}
+
+// A misbehaving adapter reporting more cache hits than prompt tokens must not
+// produce negative fresh tokens.
+func TestBillingCacheHitClampedToPrompt(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{"m": map[string]interface{}{"prompt": 1e-5, "completion": 0}},
+		},
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "s", "key": "***c", "ok": true,
+		"prompt_tokens": 100, "completion_tokens": 0,
+		"cache_hit_tokens": 999999, // nonsense from a broken adapter
+		"time":             1750000000000,
+	})
+	// Clamped to 100 cached, 0 fresh => 100 * 1e-5 * 0.1
+	got := stateOf(t, ps)["total"].(map[string]interface{})["cost"].(float64)
+	if got < 0 {
+		t.Errorf("cost = %v, must never be negative", got)
+	}
+	approx(t, "clamped cost", got, 0.0001)
+}
+
+// ---- unpriced traffic -----------------------------------------------------
+
+// An unpriced model silently costing 0 is the most dangerous failure a cost
+// plugin has: the bill still adds up, it just quietly under-reports, and
+// nothing looks broken. It must be counted and named.
+func TestBillingCountsUnpricedTraffic(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"priced": map[string]interface{}{"prompt": 1e-5},
+			},
+		},
+	})
+	// 100k+100k tokens on a model with no price entry.
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "MYSTERY-MODEL", "source": "s", "key": "***u", "ok": true,
+		"prompt_tokens": 100000, "completion_tokens": 100000, "time": 1750000000000,
+	})
+	// A priced one, to prove the counter is selective.
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "priced", "source": "s", "key": "***u", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 0, "time": 1750000000000,
+	})
+	st := stateOf(t, ps)
+	if got := st["unpriced_reqs"].(float64); got != 1 {
+		t.Errorf("unpriced_reqs = %v, want 1 (only the mystery model)", got)
+	}
+	models := st["unpriced_models"].(map[string]interface{})
+	if models["MYSTERY-MODEL"].(float64) != 1 {
+		t.Errorf("unpriced_models = %v, want MYSTERY-MODEL counted", models)
+	}
+	if _, present := models["priced"]; present {
+		t.Error("a priced model was counted as unpriced")
+	}
+	// The traffic is still recorded: "unpriced" must not mean "invisible".
+	if got := st["total"].(map[string]interface{})["requests"].(float64); got != 2 {
+		t.Errorf("total requests = %v, want 2 (unpriced traffic is still traffic)", got)
+	}
+}
+
+// A source-only or key-only price counts as priced: any dimension covering the
+// request is enough.
+func TestBillingAnyDimensionCountsAsPriced(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"sources": map[string]interface{}{"flat-fee": map[string]interface{}{"per_request": 0.02}},
+		},
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "any-model", "source": "flat-fee", "key": "***p", "ok": true,
+		"prompt_tokens": 10, "completion_tokens": 0, "time": 1750000000000,
+	})
+	st := stateOf(t, ps)
+	if got := st["unpriced_reqs"].(float64); got != 0 {
+		t.Errorf("unpriced_reqs = %v, want 0 (the source price covers it)", got)
+	}
+	approx(t, "flat fee", st["total"].(map[string]interface{})["cost"].(float64), 0.02)
+}
+
+// ---- 峰谷 / 时段定价 ---------------------------------------------------
+//
+// commandcode 的 DeepSeek V4 系列就是这么定价的：非高峰 17h/天，高峰 01-04 &
+// 06-10 UTC 工作日，价格恰好 2 倍。这类规则用静态价目无法表达，而算错方向是
+// 静默的——不会报错，只会一直算错。
+//
+// 时间判据的可测性：os.date("!%H") 取 UTC 小时。测试通过选择"确定落在窗口内"
+// 与"确定落在窗口外"的时段来判定，不去伪造时钟（Lua 侧没有可注入的时钟，
+// 伪造反而会让测试与真实行为脱节）。
+
+func TestBillingPeakWindowDoublesOutsidePeak(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"dsv41": map[string]interface{}{
+					"prompt": 1.5e-7, "completion": 6e-7,
+					"peak": map[string]interface{}{
+						"multiplier": 2,
+						// 全部 7 天全部 24 小时 ⇒ 永远命中
+						"windows": []interface{}{
+							map[string]interface{}{
+								"days":  []interface{}{0, 1, 2, 3, 4, 5, 6},
+								"hours": []interface{}{[]interface{}{0, 23}},
+							},
+						},
+					},
+				},
+			},
+		},
+	})
+	// 1000 prompt + 1000 completion，非高峰 0.00075 → 命中峰谷 ×2 = 0.0015
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "dsv41", "source": "commandcode", "key": "***pk", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 1000, "time": 1750000000000,
+	})
+	got := stateOf(t, ps)["total"].(map[string]interface{})["cost"].(float64)
+	want := (1000*1.5e-7 + 1000*6e-7) * 2
+	approx(t, "always-peak cost", got, want)
+}
+
+// 一个不存在的窗口（UTC 25 点不存在）⇒ 永不命中 ⇒ 静态价。
+func TestBillingPeakWindowNotHit(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"dsv41": map[string]interface{}{
+					"prompt": 1.5e-7, "completion": 6e-7,
+					"peak": map[string]interface{}{
+						"multiplier": 2,
+						// 星期 = {0..6} 但小时窗写成 [99,100]：永远不可能命中
+						"windows": []interface{}{
+							map[string]interface{}{
+								"days":  []interface{}{0, 1, 2, 3, 4, 5, 6},
+								"hours": []interface{}{[]interface{}{99, 100}},
+							},
+						},
+					},
+				},
+			},
+		},
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "dsv41", "source": "commandcode", "key": "***pk", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 1000, "time": 1750000000000,
+	})
+	got := stateOf(t, ps)["total"].(map[string]interface{})["cost"].(float64)
+	approx(t, "never-peak cost", got, 1000*1.5e-7+1000*6e-7)
+}
+
+// 星期不匹配 ⇒ 不命中。这一条正是"用本地时区算会整体偏移"要防的东西：
+// 周日按 UTC 算，用本地时区可能算成周六而错误地命中工作日窗口。
+func TestBillingPeakWindowDayMismatch(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"dsv41": map[string]interface{}{
+					"prompt": 1.5e-7, "completion": 6e-7,
+					"peak": map[string]interface{}{
+						"multiplier": 2,
+						// 只在"不存在的星期 7"上开窗（os.date %w 只到 0..6）
+						"windows": []interface{}{
+							map[string]interface{}{
+								"days":  []interface{}{7},
+								"hours": []interface{}{[]interface{}{0, 23}},
+							},
+						},
+					},
+				},
+			},
+		},
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "dsv41", "source": "commandcode", "key": "***pk", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 1000, "time": 1750000000000,
+	})
+	got := stateOf(t, ps)["total"].(map[string]interface{})["cost"].(float64)
+	if got > (1000*1.5e-7+1000*6e-7)*1.5 {
+		t.Errorf("cost = %v: a non-matching weekday must not trigger the peak multiplier", got)
+	}
+}
+
+// 没有 peak 规则的条目完全不受影响（向后兼容）。
+func TestBillingNoPeakRuleIsUnaffected(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"plain": map[string]interface{}{"prompt": 1e-6, "completion": 2e-6},
+			},
+		},
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "plain", "source": "s", "key": "***n", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 1000, "time": 1750000000000,
+	})
+	approx(t, "no-peak cost", stateOf(t, ps)["total"].(map[string]interface{})["cost"].(float64), 1000*1e-6+1000*2e-6)
+}
+
+// 缓存读价【不】跟着峰谷翻倍：它是另一条上游费率，观测到的非峰谷价里已经含了
+// 自己的折扣，跟着翻倍会把两个折扣叠在一起。
+func TestBillingPeakDoesNotDoubleCacheRead(t *testing.T) {
+	ps, _ := billingVM(t)
+	_ = ps.SetState("billing", map[string]interface{}{
+		"prices": map[string]interface{}{
+			"models": map[string]interface{}{
+				"dsv41": map[string]interface{}{
+					"prompt": 1.5e-7, "completion": 6e-7, "cache_discount": 0.02,
+					"peak": map[string]interface{}{
+						"multiplier": 2,
+						"windows": []interface{}{map[string]interface{}{
+							"days":  []interface{}{0, 1, 2, 3, 4, 5, 6},
+							"hours": []interface{}{[]interface{}{0, 23}},
+						}},
+					},
+				},
+			},
+		},
+	})
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "dsv41", "source": "commandcode", "key": "***c", "ok": true,
+		"prompt_tokens": 1000000, "completion_tokens": 0,
+		"cache_hit_tokens": 1000000, "time": 1750000000000,
+	})
+	// 全部缓存命中 ⇒ 只按 cache 价 = prompt * 0.02，且不翻倍
+	got := stateOf(t, ps)["total"].(map[string]interface{})["cost"].(float64)
+	approx(t, "cache-only cost (not doubled)", got, 1e6*1.5e-7*0.02)
+}
+
+// TestBillingTracksCacheUsage is the guard for the gap production exposed: the
+// gateway had prompt_cache_hit_tokens and costFor() priced the cache leg, but no
+// bucket recorded the number. On a gateway where 99.88% of prompt tokens were
+// cache reads, the report showed a prompt_tokens figure with no way to tell that
+// most of it was cached.
+func TestBillingTracksCacheUsage(t *testing.T) {
+	ps, _ := billingVM(t)
+
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "s", "key": "k", "ok": true,
+		"prompt_tokens": 1000, "completion_tokens": 50,
+		"cache_hit_tokens": 900, "cache_reported": true,
+	})
+	// A second request from a source that does not report caching at all.
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m2", "source": "s2", "ok": true,
+		"prompt_tokens": 100, "completion_tokens": 10,
+	})
+
+	st := ps.State("billing").(map[string]interface{})
+	total := st["total"].(map[string]interface{})
+	if total["cache_hit_tokens"] != float64(900) {
+		t.Errorf("total.cache_hit_tokens = %v, want 900", total["cache_hit_tokens"])
+	}
+	if total["cache_fresh_tokens"] != float64(200) {
+		t.Errorf("total.cache_fresh_tokens = %v, want 200 (1000-900 + 100)", total["cache_fresh_tokens"])
+	}
+	// Only the first request reported a cache number.
+	if total["cache_reported_reqs"] != float64(1) {
+		t.Errorf("★ total.cache_reported_reqs = %v, want 1 — a source that never "+
+			"reports cache usage must be distinguishable from one reporting zero hits",
+			total["cache_reported_reqs"])
+	}
+
+	// Per-source separation.
+	bySrc := st["by_source"].(map[string]interface{})
+	s1 := bySrc["s"].(map[string]interface{})
+	if s1["cache_hit_tokens"] != float64(900) {
+		t.Errorf("by_source[s].cache_hit_tokens = %v, want 900", s1["cache_hit_tokens"])
+	}
+	s2 := bySrc["s2"].(map[string]interface{})
+	if s2["cache_reported_reqs"] != float64(0) {
+		t.Errorf("by_source[s2].cache_reported_reqs = %v, want 0", s2["cache_reported_reqs"])
+	}
+	if s2["cache_fresh_tokens"] != float64(100) {
+		t.Errorf("by_source[s2].cache_fresh_tokens = %v, want 100", s2["cache_fresh_tokens"])
+	}
+}
+
+// TestBillingCacheBucketsSurviveOlderStateFiles: a state file written before these
+// fields existed must not crash the hook. `nil + number` is an error in Lua, and
+// a hook that throws stops accounting for that request entirely — which is how a
+// billing gap turns into a silent one.
+func TestBillingCacheBucketsSurviveOlderStateFiles(t *testing.T) {
+	ps, _ := billingVM(t)
+	// Simulate a state restored from an older build: buckets without the new keys.
+	legacy := map[string]interface{}{
+		"total": map[string]interface{}{
+			"cost": 1.0, "requests": float64(5), "prompt_tokens": float64(500),
+			"completion_tokens": float64(50), "failures": float64(0),
+		},
+		"by_source": map[string]interface{}{
+			"legacy": map[string]interface{}{"cost": float64(0), "requests": float64(5),
+				"prompt_tokens": float64(500), "completion_tokens": float64(50), "failures": float64(0)},
+		},
+		"by_model": map[string]interface{}{}, "by_key": map[string]interface{}{},
+		"by_day": map[string]interface{}{}, "started": float64(0),
+	}
+	if err := ps.SetState("billing", legacy); err != nil {
+		t.Fatalf("SetState: %v", err)
+	}
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "legacy", "ok": true,
+		"prompt_tokens": 100, "completion_tokens": 10,
+		"cache_hit_tokens": 60, "cache_reported": true,
+	})
+	if len(ps.HookErrors()) != 0 {
+		t.Fatalf("hook error on a legacy state: %v", ps.HookErrors())
+	}
+	st := ps.State("billing").(map[string]interface{})
+	tot := st["total"].(map[string]interface{})
+	if tot["requests"] != float64(6) {
+		t.Errorf("requests = %v, want 6 (5 legacy + 1 new)", tot["requests"])
+	}
+	if tot["cache_hit_tokens"] != float64(60) {
+		t.Errorf("cache_hit_tokens = %v, want 60", tot["cache_hit_tokens"])
+	}
+	lg := st["by_source"].(map[string]interface{})["legacy"].(map[string]interface{})
+	if lg["cache_hit_tokens"] != float64(60) {
+		t.Errorf("legacy bucket cache_hit_tokens = %v, want 60", lg["cache_hit_tokens"])
+	}
+}
+
+// TestBillingCacheHitClampedInStats: costFor clamps the cache leg, so the
+// recorded numbers must be clamped the same way. A provider that reports more
+// cache hits than prompt tokens must not produce negative fresh tokens.
+func TestBillingCacheHitClampedInStats(t *testing.T) {
+	ps, _ := billingVM(t)
+	ps.Fire(StageRequestEnd, map[string]interface{}{
+		"model": "m", "source": "s", "ok": true,
+		"prompt_tokens": 100, "completion_tokens": 5,
+		"cache_hit_tokens": 5000, "cache_reported": true,
+	})
+	st := ps.State("billing").(map[string]interface{})
+	tot := st["total"].(map[string]interface{})
+	if tot["cache_hit_tokens"] != float64(100) {
+		t.Errorf("★ cache_hit_tokens = %v, want 100 (clamped to prompt_tokens)",
+			tot["cache_hit_tokens"])
+	}
+	if tot["cache_fresh_tokens"] != float64(0) {
+		t.Errorf("★ cache_fresh_tokens = %v, want 0, never negative",
+			tot["cache_fresh_tokens"])
+	}
+}

internal/lua/billing_ui_test.go

@@ -0,0 +1,416 @@
+package lua
+
+import (
+	"encoding/json"
+	"os"
+	"os/exec"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// The billing page rendered EMPTY in production while its data endpoint returned
+// 200 with real numbers. The cause was one line: render(st) referenced an
+// undefined `s` for two KPI cells, so the ReferenceError aborted the whole
+// render and every table stayed at its initial empty innerHTML.
+//
+// Nothing in the build, the tests or the API surfaced it. This file is the guard
+// for the whole class: a plugin's injected UI that references an undefined name,
+// or that depends on a container the page does not provide, fails silently.
+
+// billingUI returns the injected markup for the billing plugin: the full page
+// mount and the status-page element mount.
+func billingUI(t *testing.T) (page string, statusElement string) {
+	t.Helper()
+	src, err := os.ReadFile("plugins/billing.lua")
+	if err != nil {
+		t.Fatalf("read billing.lua: %v", err)
+	}
+	// Located BY CONTENT, not by index. The plugin also uses a long string for
+	// its inline SVG icon, so "the first long string" is the icon and "the
+	// second" is the page — which is exactly the kind of positional assumption
+	// that breaks the next time an icon or a description is added.
+	page = longStringContaining(t, string(src), "billing-root")
+	statusElement = longStringContaining(t, string(src), "billing-status-tile")
+	return page, statusElement
+}
+
+// longStringContaining returns the [==[ ... ]==] body that contains marker.
+func longStringContaining(t *testing.T, src, marker string) string {
+	t.Helper()
+	re := regexp.MustCompile(`(?s)\[==\[(.*?)\]==\]`)
+	for _, m := range re.FindAllStringSubmatch(src, -1) {
+		if strings.Contains(m[1], marker) {
+			return m[1]
+		}
+	}
+	t.Fatalf("no long string contains %q", marker)
+	return ""
+}
+
+// TestBillingMountScriptExecutes is the guard for the production bug.
+//
+// The Billing page rendered empty while its data endpoint returned 200 with real
+// numbers. Cause: render(st) referenced an undefined `s` for two KPI cells, the
+// ReferenceError aborted the render, and every table kept its initial empty
+// innerHTML. Nothing in the build or the API surfaced it.
+//
+// Two earlier attempts at a static check were both wrong: a "declared names"
+// scan flagged every CSS class inside the inline HTML strings (class, div, td),
+// and a CSS-selector parse of the stylesheet reported the stylesheet itself as
+// broken. Static analysis of JS embedded in HTML strings is the wrong tool.
+//
+// So this actually RUNS the script, in node, against a minimal DOM stub, and
+// fails on any thrown error. Skipped when node is unavailable, with the reason
+// printed — never silently passing as if it had checked.
+func TestBillingMountScriptExecutes(t *testing.T) {
+	page, el := billingUI(t)
+	scripts := extractScripts(page)
+	if len(scripts) == 0 {
+		t.Fatal("no <script> found in the billing page mount")
+	}
+	for i, js := range scripts {
+		assertRendersAndDoesNotThrow(t, i, js)
+	}
+	for i, js := range extractScripts(el) {
+		assertRendersAndDoesNotThrow(t, i, js)
+	}
+}
+
+// assertRendersAndDoesNotThrow executes a mount script under node against a DOM
+// stub and fails on EITHER a thrown/reported error OR an empty render.
+//
+// Checking only for exceptions is not enough, and that is the third wrong
+// attempt at this guard. The plugin's render() opens with `if (!st) return;`,
+// so passing the wrong field (`render(j.stateX)`) is a SILENT no-op: no throw,
+// no console.error, no rejection — just an empty page. Only looking at the
+// produced DOM catches that class.
+func assertRendersAndDoesNotThrow(t *testing.T, idx int, js string) {
+	t.Helper()
+	node, err := exec.LookPath("node")
+	if err != nil {
+		t.Skipf("node not available (%v): cannot execute the injected script", err)
+	}
+
+	stub := `
+global.window = global;
+global.document = {
+  getElementById: function (id) {
+    if (!global.__els) global.__els = {};
+    if (!global.__els[id]) global.__els[id] = {
+      style: {}, dataset: {}, classList: { add: function(){}, remove: function(){} },
+      // Both writes count: the Billing page fills innerHTML, the status-page
+      // tile assigns textContent. Watching only one of them flagged the tile as
+      // "renders nothing" — a false positive that would have taught everyone to
+      // ignore this test.
+      set innerHTML(v) { if (v && String(v).trim()) global.__written.push(id); this.__h = v; },
+      get innerHTML() { return this.__h || ""; },
+      set textContent(v) { if (v !== undefined && String(v).trim()) global.__written.push(id); this.__t = v; },
+      get textContent() { return this.__t || ""; },
+      set innerText(v) { if (v !== undefined && String(v).trim()) global.__written.push(id); this.__i = v; },
+      get innerText() { return this.__i || ""; },
+      appendChild: function(){}, querySelector: function(){ return null; },
+      querySelectorAll: function(){ return []; }, addEventListener: function(){} };
+    return global.__els[id];
+  },
+  createElement: function () { return { style: {}, dataset: {}, appendChild: function(){}, setAttribute: function(){} }; },
+  addEventListener: function () {},
+};
+global.pluginAPI = { onTabShown: function () {} };
+global.fetch = function () {
+  // A payload with real numbers, so a working render produces visible output.
+  return Promise.resolve({ ok: true, json: function () {
+    return Promise.resolve({ plugin: "billing", state: {
+      currency: "USD",
+      total: { cost: 1.25, requests: 7, prompt_tokens: 100, completion_tokens: 20, failures: 0 },
+      by_source: { localzen: { cost: 1.25, requests: 7, prompt_tokens: 100, completion_tokens: 20, failures: 0 } },
+      by_model: { m1: { cost: 1.25, requests: 7, prompt_tokens: 100, completion_tokens: 20, failures: 0 } },
+      by_key: { k1: { cost: 1.25, requests: 7, prompt_tokens: 100, completion_tokens: 20, failures: 0 } },
+      by_day: { "2026-01-01": { cost: 1.25, requests: 7, prompt_tokens: 100, completion_tokens: 20, failures: 0 } },
+      degraded_reqs: 1, unpriced_reqs: 2,
+    }});
+  }});
+};
+global.__written = [];
+global.__errors = [];
+// The plugin's refresh() swallows its own errors so decoration can never break
+// the host page — which is right, and is exactly why the production ReferenceError
+// was invisible. So the trace has to come from console.error, which the plugin now
+// emits. Hooking process events alone made this test pass against the very bug it
+// was written for (verified by re-introducing the typo and watching it stay green).
+var __realErr = console.error;
+console.error = function () {
+  global.__errors.push("console.error: " + Array.prototype.map.call(arguments, function (a) {
+    return (a && a.message) ? a.message : String(a);
+  }).join(" "));
+  __realErr.apply(console, arguments);
+};
+process.on("uncaughtException", function (e) { global.__errors.push("uncaught: " + String(e && e.message || e)); });
+process.on("unhandledRejection", function (e) { global.__errors.push("unhandled: " + String(e && e.message || e)); });
+`
+	// 50ms is not a guess: the plugin's IIFE kicks off refresh() which awaits a
+	// fetch; a rejection lands on the microtask queue almost immediately.
+	script := strings.Join([]string{
+		stub, js,
+		`setTimeout(function(){
+   console.log("__ERRS__" + JSON.stringify({errors: global.__errors, written: global.__written}));
+ }, 300);`,
+	}, "\n")
+	cmd := exec.Command(node, "-e", script)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Errorf("mount script %d crashed under node: %v\n%s", idx, err, out)
+		return
+	}
+	// The script may print other things; find the JSON we appended.
+	line := ""
+	for _, l := range strings.Split(string(out), "\n") {
+		if i := strings.Index(l, "__ERRS__"); i >= 0 {
+			line = strings.TrimSpace(l[i+len("__ERRS__"):])
+		}
+	}
+	if line == "" {
+		t.Errorf("mount script %d produced no error report — the harness did not "+
+			"run to completion, so it cannot be trusted to have checked anything", idx)
+		return
+	}
+	var report struct {
+		Errors  []string `json:"errors"`
+		Written []string `json:"written"`
+	}
+	if err := json.Unmarshal([]byte(line), &report); err != nil {
+		t.Errorf("could not parse the error report %q: %v", line, err)
+		return
+	}
+	for _, e := range report.Errors {
+		t.Errorf("mount script %d reported %q — this is the failure that leaves "+
+			"the Billing page blank while the API still returns data", idx, e)
+	}
+	if len(report.Written) == 0 {
+		t.Errorf("mount script %d wrote NOTHING into any container — the page "+
+			"renders empty. render() guards with `if (!st) return`, so a wrong "+
+			"field name is a silent no-op: no throw, no console output, no error "+
+			"anywhere. This is what the production page looked like.", idx)
+	}
+}
+
+func extractScripts(html string) []string {
+	re := regexp.MustCompile(`(?s)<script[^>]*>(.*?)</script>`)
+	var out []string
+	for _, m := range re.FindAllStringSubmatch(html, -1) {
+		out = append(out, m[1])
+	}
+	return out
+}
+
+// TestBillingPageCoversItsData is the other half: the page declares tables for
+// per-source / per-model / per-key / per-day and must actually render into them.
+// A table id that is never written to is exactly how "the page loads and shows
+// nothing" happens without an error.
+func TestBillingPageCoversItsData(t *testing.T) {
+	page, _ := billingUI(t)
+	for _, id := range []string{
+		"billing-kpis", "billing-by-source", "billing-by-model",
+		"billing-by-key", "billing-by-day",
+	} {
+		if !strings.Contains(page, `id="`+id+`"`) {
+			t.Errorf("the page has no container #%s", id)
+		}
+	}
+	// Every container must be written to by the script, not just declared.
+	scripts := extractScripts(page)
+	all := strings.Join(scripts, "\n")
+	for _, id := range []string{"billing-kpis", "billing-by-source", "billing-by-model", "billing-by-key", "billing-by-day"} {
+		if !strings.Contains(all, `getElementById("`+id+`")`) {
+			t.Errorf("#%s is declared but never read by the script — it stays empty forever", id)
+		}
+	}
+}
+
+// TestPluginIconIsNotARawEmoji guards the sidebar icon. The billing plugin
+// declared icon = "💰" and the WebUI drops that verbatim into the button, while
+// every native tab uses an inline SVG styled with `stroke: currentColor`. An
+// emoji there renders at the wrong size and ignores the theme, so it does not
+// match its neighbours — which is what the operator reported.
+func TestPluginIconIsNotARawEmoji(t *testing.T) {
+	icon := billingIcon(mustBillingSource(t))
+	if icon == "" {
+		t.Fatal("billing declares no icon; the sidebar entry would be blank")
+	}
+	if isEmojiIcon(icon) {
+		t.Errorf("page icon is the raw emoji %q — the WebUI sidebar renders "+
+			"native tabs as inline SVG (stroke: currentColor), so an emoji is the "+
+			"wrong size and ignores the theme. Use an inline SVG path instead.", icon)
+	}
+}
+
+// isEmojiIcon reports whether s is a pictographic emoji rather than markup or a
+// text glyph. Codepoints in the pictographic blocks, plus the regional-indicator
+// pair used by flags.
+func isEmojiIcon(s string) bool {
+	r := []rune(s)
+	if len(r) == 0 {
+		return false
+	}
+	// Anything containing '<' is markup (an inline <svg>), which is the fix.
+	if strings.ContainsRune(s, '<') {
+		return false
+	}
+	for _, c := range r {
+		switch {
+		case c >= 0x1F300 && c <= 0x1FAFF, // pictographs, symbols, supplemental
+			c >= 0x1F000 && c <= 0x1F2FF, // mahjong/domino/cards
+			c >= 0x2600 && c <= 0x27BF,   // misc symbols + dingbats
+			c >= 0x2B00 && c <= 0x2BFF,   // arrows/misc symbols
+			c == 0xFE0F,                  // variation selector-16
+			c >= 0x1F1E6 && c <= 0x1F1FF: // regional indicators (flags)
+			return true
+		}
+	}
+	return false
+}
+
+func mustBillingSource(t *testing.T) string {
+	t.Helper()
+	b, err := os.ReadFile("plugins/billing.lua")
+	if err != nil {
+		t.Fatal(err)
+	}
+	return string(b)
+}
+
+// billingIcon extracts the declared page icon. It accepts BOTH a quoted string
+// and a [==[ ... ]==] long string, because an inline SVG cannot be written as a
+// Lua short string without escaping every quote in it.
+func billingIcon(src string) string {
+	if m := regexp.MustCompile(`(?m)^\s*icon\s*=\s*"([^"]*)"`).FindStringSubmatch(src); m != nil {
+		return m[1]
+	}
+	if m := regexp.MustCompile(`(?s)\bicon\s*=\s*\[==\[(.*?)\]==\]`).FindStringSubmatch(src); m != nil {
+		return m[1]
+	}
+	return ""
+}
+
+// TestBillingTableHeaderMatchesRowColumns catches column drift.
+//
+// row() gained cache columns (fresh / cache / cache%) while the header row did
+// not, in the same edit. The result is a table whose cells are shifted one
+// column left from "fresh" onward — so "cache%" sits under "completion" and the
+// last cell has no label. It renders, it has data, and it is wrong in a way that
+// takes a careful read to notice.
+func TestBillingTableHeaderMatchesRowColumns(t *testing.T) {
+	page, _ := billingUI(t)
+	js := strings.Join(extractScripts(page), "\n")
+	if !strings.Contains(js, "<th>") {
+		t.Fatal("no table header found in the billing page script")
+	}
+	hStart := strings.Index(js, "function tableFor")
+	if hStart < 0 {
+		t.Fatal("no tableFor in the billing page script")
+	}
+	// Count the usage table's headers ONLY. The count is taken from tableFor to
+	// the end of the script, which used to be fine when the rule editor lived on
+	// its own page; now that both halves share one script, the rule table's nine
+	// headers were counted too and the check reported 17 vs 8 — a failure about
+	// two unrelated tables. Stop at the rule editor's script.
+	header := js[hStart:]
+	if cut := strings.Index(header, "/api/plugins/billing/rules"); cut > 0 {
+		header = header[:cut]
+	}
+	// Count <th> with OR without attributes: the name column now carries
+	// style='width:22%' so the header and its data cell can be given the same
+	// width, and a bare "<th>" count silently reported 7 vs 8 — the check
+	// failing on the very column it had just been taught to size.
+	th := strings.Count(header, "<th>") + strings.Count(header, "<th ")
+
+	rStart := strings.Index(js, "function row")
+	rEnd := strings.Index(js, "function tableFor")
+	if rStart < 0 || rEnd < 0 || rEnd <= rStart {
+		t.Fatal("could not isolate row()")
+	}
+	row := js[rStart:rEnd]
+	// Each cell closes with </td>; the first cell uses <td><b>..</b></td> so
+	// counting </td> is exact.
+	td := strings.Count(row, "</td>")
+
+	if th != td {
+		t.Errorf("★ header declares %d columns but row() emits %d cells — the "+
+			"table is misaligned from the first differing column on", th, td)
+	}
+}
+
+// TestRuleTableLocksColumnWidthsInAColgroup guards the layout class of bug that
+// only a screenshot caught: two adjacent headers rendered on top of each other,
+// the URL input squeezed to "https:", and the per-model × button landing 78px
+// past its cell onto the neighbouring Delete button.
+//
+// The measurement that found each one:
+//   - table-layout:fixed with widths on <td> → 954px divided into 9 equal
+//     106px columns, every declared width discarded.
+//   - widths on <th> WITHOUT fixed → browser sizes from content and ignores
+//     them; the 70px currency column still collapsed to 48px (24px of input).
+//   - fixed + <th> widths → they take effect, but the model-price cell's width
+//     then depended on WHICH RULE was widest (352px vs 206px).
+//
+// The fix is all three together: fixed layout, a colgroup, and flex children
+// that may shrink.
+func TestRuleTableLocksColumnWidthsInAColgroup(t *testing.T) {
+	page, _ := billingUI(t)
+	js := strings.Join(extractScripts(page), "\n")
+	// Match the ATTRIBUTE, not the bare string: a substring check on
+	// "table-layout:fixed" is satisfied by the explanatory comment that sits
+	// three lines above the tag, so removing the attribute from the table still
+	// passed (mutation-verified). Require it inside a style='...' literal.
+	if !strings.Contains(js, `font-size:12px;table-layout:fixed'`) {
+		t.Error("the rule table must stay table-layout:fixed — with auto layout " +
+			"the <colgroup> widths below are ignored and columns size from content")
+	}
+	colStart := strings.Index(js, "<colgroup>")
+	if colStart < 0 {
+		t.Fatal("the rule table declares no <colgroup>; per-column widths on " +
+			"<th> or <td> are advisory and get recomputed from content")
+	}
+	// The colgroup is built from a JS array of pixel widths, so assert on the
+	// array, not on literal "<col " occurrences — counting the literal found
+	// exactly one and reported "1 columns, want 9" against correct code.
+	if !strings.Contains(js, "[214, 80, 62, 70, 66, 74, 62, 262, 74]") {
+		t.Error("the rule table's colgroup widths changed or vanished; measured " +
+			"values were [214 80 62 70 66 74 62 262 74] for a 954px pane — the " +
+			"delete column needs 74px or the button wraps to two lines")
+	}
+	if !strings.Contains(js, `"<col style='width:" + w + "px'>"`) {
+		t.Error("colgroup entries are no longer emitted as <col style='width:Npx'>")
+	}
+	// Every price-row INPUT must be allowed to shrink, or the row's fixed widths
+	// sum past the cell and the × button lands on the next column. The × button
+	// is the opposite: it must NOT shrink (flex:0 0 auto), because a squashed
+	// delete button is unclickable.
+	for _, needle := range []string{"m-name", "m-p", "m-c"} {
+		i := strings.Index(js, "class='"+needle+"'")
+		if i < 0 {
+			i = strings.Index(js, "class='ghost small "+needle+"'")
+		}
+		if i < 0 {
+			t.Errorf("price row lost the %s input/button", needle)
+			continue
+		}
+		window := js[i : i+220]
+		if !strings.Contains(window, "flex:") {
+			t.Errorf("%s has no flex sizing; the row is 80+96+96+38 ≈ 330px wide "+
+				"against a 262px cell and overflows onto the next column", needle)
+		}
+		if !strings.Contains(window, "min-width:0") {
+			t.Errorf("%s lacks min-width:0; a flex item will not shrink below its "+
+				"content width, which is how the × button ended up 78px past its cell", needle)
+		}
+	}
+	i := strings.Index(js, "class='ghost small m-del'")
+	if i < 0 {
+		t.Fatal("the per-model delete button is gone")
+	}
+	if !strings.Contains(js[i:i+120], "flex:0 0 auto") {
+		t.Error("the per-model × button must be flex:0 0 auto — it is a fixed-size " +
+			"control and must never be squeezed by the flexible inputs")
+	}
+}

internal/lua/fastvalue.go

@@ -0,0 +1,139 @@
+package lua
+
+import (
+	"encoding/json"
+	"strconv"
+)
+
+// This file exists to remove the JSON round-trip from the plugin hook path.
+//
+// Measured before this change: one Fire() call cost 14.6us, of which
+// json.Marshal(payload) was 4.0us and json.Unmarshal back into interface{} was
+// 5.6us — 67% of the whole hook, spent re-deriving a tree that the very next
+// line (pushGoValue) already knows how to walk natively.
+//
+// The round-trip existed because payload arrives as map[string]interface{} and
+// pushGoValue wanted a plain interface{} tree. pushGoValue already handles
+// map[string]interface{} and []interface{} directly, so the fix is a converter
+// that flattens the concrete Go types the gateway actually produces, instead of
+// a generic serialize/parse.
+//
+// The JSON path is kept as the fallback for types the fast path does not know,
+// so a plugin payload carrying something exotic still arrives rather than being
+// silently dropped.
+
+// jsonNumberType is the type json.Unmarshal produces for every JSON number.
+// The fast path recognizes it so numbers survive as numbers rather than being
+// stringified into a different Lua type.
+type jsonNumberType = float64
+
+// fastToPlain converts the concrete Go values the gateway puts in a hook
+// payload into the interface{} tree pushGoValue consumes, without JSON.
+//
+// The interesting cases are the ones json.Unmarshal would have normalized:
+//   - json.Number-ish types (all float64 in practice)
+//   - int / int64 / uint variants, which must land as Lua numbers, not as the
+//     strings a naive "only handle float64" switch would produce
+//   - []string and map[string]string, extremely common in payloads and NOT
+//     handled by a switch that only knows []interface{}
+//
+// Anything unrecognized returns (value, false) so the caller can fall back to
+// the JSON path, which is slower but total.
+func fastToPlain(v interface{}) (interface{}, bool) {
+	switch x := v.(type) {
+	case nil, bool, string, jsonNumberType:
+		return v, true
+	case int:
+		return float64(x), true
+	case int8:
+		return float64(x), true
+	case int16:
+		return float64(x), true
+	case int32:
+		return float64(x), true
+	case int64:
+		return float64(x), true
+	case uint:
+		return float64(x), true
+	case uint8:
+		return float64(x), true
+	case uint16:
+		return float64(x), true
+	case uint32:
+		return float64(x), true
+	case uint64:
+		return float64(x), true
+	case float32:
+		return float64(x), true
+	case []string:
+		out := make([]interface{}, len(x))
+		for i, s := range x {
+			out[i] = s
+		}
+		return out, true
+	case map[string]string:
+		out := make(map[string]interface{}, len(x))
+		for k, s := range x {
+			out[k] = s
+		}
+		return out, true
+	case map[string]interface{}:
+		// The overwhelmingly common case, and the one the hook path always
+		// takes at the top level.
+		out := make(map[string]interface{}, len(x))
+		for k, it := range x {
+			c, ok := fastToPlain(it)
+			if !ok {
+				return nil, false
+			}
+			out[k] = c
+		}
+		return out, true
+	case []interface{}:
+		out := make([]interface{}, len(x))
+		for i, it := range x {
+			c, ok := fastToPlain(it)
+			if !ok {
+				return nil, false
+			}
+			out[i] = c
+		}
+		return out, true
+	default:
+		return nil, false
+	}
+}
+
+// plainForLua returns the interface{} tree to hand to pushGoValue, using the
+// fast path when it can and JSON only when it must.
+func plainForLua(payload map[string]interface{}) interface{} {
+	if fast, ok := fastToPlain(payload); ok {
+		return fast
+	}
+	// Rare: some type the fast path does not model. Serialize and let the
+	// generic decoder normalize it, so the hook still sees the field.
+	b, err := json.Marshal(payload)
+	if err != nil {
+		return payload
+	}
+	var decoded interface{}
+	if err := json.Unmarshal(b, &decoded); err != nil {
+		return payload
+	}
+	return decoded
+}
+
+// toPlainSlice is the []interface{} entry point of fastToPlain, exposed so the
+// Fire path can flatten a pre-built slice without re-walking the map header.
+func toPlainSlice(v []interface{}) []interface{} {
+	if fast, ok := fastToPlain(v); ok {
+		return fast.([]interface{})
+	}
+	return v
+}
+
+// luaNumberString renders a float the way Lua would print it, for the rare case
+// a hook wants the textual form. Kept out of the hot path.
+func luaNumberString(f float64) string {
+	return strconv.FormatFloat(f, 'g', -1, 64)
+}

internal/lua/fastvalue_test.go

@@ -0,0 +1,132 @@
+package lua
+
+import (
+	"encoding/json"
+	"reflect"
+	"testing"
+)
+
+// The hook payload used to be JSON round-tripped on every call. It no longer is,
+// so the fast path and the old JSON path must be indistinguishable — otherwise
+// a plugin silently sees a different payload than before, which is the worst
+// kind of change: it compiles, passes a smoke test, and misprices traffic.
+//
+// These tests therefore compare the two paths on the SAME inputs rather than
+// asserting the fast path's output in isolation.
+
+func viaJSON(t *testing.T, payload map[string]interface{}) interface{} {
+	t.Helper()
+	b, err := json.Marshal(payload)
+	if err != nil {
+		t.Fatalf("marshal: %v", err)
+	}
+	var decoded interface{}
+	if err := json.Unmarshal(b, &decoded); err != nil {
+		t.Fatalf("unmarshal: %v", err)
+	}
+	return decoded
+}
+
+// payloads that exercise every branch of the fast converter.
+func payloadCases() []map[string]interface{} {
+	return []map[string]interface{}{
+		{"model": "deepseek-v4.1-flash", "source": "commandcode", "ok": true},
+		// Numbers of every width: a converter that only knows float64 turns
+		// ints into something else, and a token count that arrives as a string
+		// makes a Lua hook do arithmetic on nil.
+		{"i": 42, "i8": int8(8), "i16": int16(16), "i32": int32(32), "i64": int64(1 << 40),
+			"u": uint(7), "u64": uint64(1 << 50), "f32": float32(1.5), "f64": 2.25},
+		// Zero, negative, and very large values must stay numbers.
+		{"zero": 0, "neg": -17, "huge": 1e308, "tiny": 1e-308},
+		// Slices and string maps: common in payloads and absent from a switch
+		// that only knows []interface{} / map[string]interface{}.
+		{"msgs": []interface{}{"a", "b"}, "tags": []string{"x", "y"}},
+		{"kv": map[string]string{"a": "1", "b": "2"}},
+		// Nesting, which is where a shallow converter silently drops a level.
+		{"usage": map[string]interface{}{
+			"prompt_tokens": 2048, "cache_hit_tokens": 1024,
+			"nested": map[string]interface{}{"deep": []interface{}{1, "two", true, nil}},
+		}},
+		{"nil_field": nil, "empty_map": map[string]interface{}{}, "empty_slice": []interface{}{}},
+		// A value the fast path does NOT model: it must fall back to JSON and
+		// still arrive, not disappear.
+		{"weird": struct {
+			A int    `json:"a"`
+			B string `json:"b"`
+		}{1, "x"}},
+	}
+}
+
+func TestFastPathMatchesJSONPath(t *testing.T) {
+	for i, p := range payloadCases() {
+		want := viaJSON(t, p)
+		got := plainForLua(p)
+		if !reflect.DeepEqual(want, got) {
+			t.Errorf("case %d: fast path differs from JSON path\n payload: %#v\n  json: %#v\n  fast: %#v",
+				i, p, want, got)
+		}
+	}
+}
+
+// TestFastPathIsActuallyUsed guards against the fast path silently degrading to
+// JSON for the payload the gateway really sends. If a future payload gains a
+// type the converter does not model, this still works (it falls back) but the
+// optimization is gone — and the next person measuring the hook would be
+// measuring the old cost without knowing why.
+func TestFastPathIsActuallyUsed(t *testing.T) {
+	// This mirrors the real request_end payload shape from the gateway.
+	realistic := map[string]interface{}{
+		"stage": "request_end", "kind": "end", "model": "deepseek-v4.1-flash",
+		"source": "commandcode", "key": "stress-key", "ok": true,
+		"status": 200, "duration_ms": 1234,
+		"usage": map[string]interface{}{
+			"prompt_tokens": float64(2048), "completion_tokens": float64(512),
+			"cache_hit_tokens": float64(1024), "total_tokens": float64(3584),
+		},
+		"walk": []interface{}{
+			map[string]interface{}{"kind": "tier_skip", "tier": 1, "source": "", "model": "", "reason": "cooldown"},
+			map[string]interface{}{"kind": "selected", "tier": 2, "source": "commandcode", "model": "m", "reason": ""},
+		},
+		"ts": float64(1700000000),
+	}
+	if _, ok := fastToPlain(realistic); !ok {
+		t.Errorf("★ the realistic request payload does NOT take the fast path — " +
+			"the JSON round-trip is still on the hot path for real traffic")
+	}
+}
+
+// TestFastPathDoesNotAliasInput: the converter builds a new tree. If it ever
+// returned the caller's map directly, a Lua hook's writes could not reach Go —
+// but worse, a later mutation of the payload would race with the snapshot the
+// persistence saver is holding.
+func TestFastPathDoesNotAliasInput(t *testing.T) {
+	src := map[string]interface{}{
+		"usage": map[string]interface{}{"prompt_tokens": float64(1)},
+		"list":  []interface{}{"a"},
+	}
+	out, ok := fastToPlain(src)
+	if !ok {
+		t.Fatal("fast path declined a plain payload")
+	}
+	m := out.(map[string]interface{})
+	m["new"] = "added"
+	src["also_new"] = "must not appear"
+
+	if _, leaked := m["also_new"]; leaked {
+		t.Error("output map aliases the input map")
+	}
+	if _, leaked := src["new"]; leaked {
+		t.Error("writing to the output mutated the input")
+	}
+	// And the nested maps must be copies too.
+	inner := m["usage"].(map[string]interface{})
+	inner["prompt_tokens"] = float64(999)
+	if src["usage"].(map[string]interface{})["prompt_tokens"] != float64(1) {
+		t.Error("nested map is shared, not copied — a hook could mutate the payload")
+	}
+	list := m["list"].([]interface{})
+	list[0] = "changed"
+	if src["list"].([]interface{})[0] != "a" {
+		t.Error("nested slice is shared, not copied")
+	}
+}

internal/lua/fire_parallel_test.go

@@ -0,0 +1,334 @@
+package lua
+
+import (
+	"os"
+	"path/filepath"
+	"sync"
+	"testing"
+	"time"
+)
+
+// Fire runs same-stage hooks in parallel across plugins. These tests pin the
+// three things that make that safe, each of which failed at least once while
+// the change was being written.
+
+// twoHookPlugins loads two plugins that both hook request_end.
+func twoHookPlugins(t *testing.T, codeA, codeB string) *Plugins {
+	t.Helper()
+	vm := NewVM(filepath.Join(t.TempDir(), "adapters"))
+	if err := vm.Start(); err != nil {
+		t.Fatalf("vm start: %v", err)
+	}
+	t.Cleanup(vm.Stop)
+	ps := NewPlugins(vm, filepath.Join(t.TempDir(), "plugins"))
+	ps.save.setWakeDelayForTest(time.Millisecond)
+	t.Cleanup(ps.Close)
+	ps.DisableStatePersistence()
+	if err := ps.LoadSource("aaa", codeA); err != nil {
+		t.Fatalf("load aaa: %v", err)
+	}
+	if err := ps.LoadSource("bbb", codeB); err != nil {
+		t.Fatalf("load bbb: %v", err)
+	}
+	return ps
+}
+
+func counterPlugin(name string, key string) string {
+	// Built by concatenation rather than fmt: %q is not a Go verb, and the first
+	// attempt produced Lua source with a stray '=' that only failed at compile
+	// time inside three different tests.
+	return `
+local p = { name = "` + name + `" }
+p.state = { n = 0 }
+p.hooks = { request_end = "bump" }
+function p.bump(payload)
+  p.state.n = p.state.n + 1
+  if "` + key + `" ~= "" then return { who = "from-` + name + `" } end
+  return nil
+end
+return p
+`
+}
+
+// TestSingleAndParallelPathsMergeIdentically: the single-plugin fast path and
+// the multi-plugin parallel path must produce the same payload.
+//
+// This is not theoretical. The parallel path was written first and the
+// single-plugin path kept its old shape; the merge loop was left off the fast
+// path, so a lone plugin returning a table had its return value DISCARDED. The
+// existing stage-order test caught it — but only because it happened to check
+// the payload after Fire. A plugin that returned fields nobody read would have
+// broken silently.
+func TestSingleAndParallelPathsMergeIdentically(t *testing.T) {
+	single := twoHookPlugins(t, counterPlugin("aaa", "who"), `
+local p = { name = "zzz" }
+p.state = { n = 0 }
+p.hooks = { request_end = "bump" }
+function p.bump(payload) p.state.n = p.state.n + 1 return nil end
+return p
+`)
+	// remove the second so exactly one plugin hooks this stage
+	single.mu.Lock()
+	single.plugins = single.plugins[:1]
+	single.mu.Unlock()
+	single.rebuild()
+
+	ps := twoHookPlugins(t, counterPlugin("aaa", "who"), counterPlugin("bbb", "who"))
+
+	singleOut := single.Fire(StageRequestEnd, map[string]interface{}{"model": "m"})
+	psOut := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m"})
+
+	if singleOut["who"] != "from-aaa" {
+		t.Errorf("★ single-plugin path dropped the return value: %v", singleOut)
+	}
+	// Two plugins both return `who`; the merge order decides the winner, and it
+	// must be deterministic (load order), not scheduler-dependent.
+	if psOut["who"] != "from-bbb" {
+		t.Errorf("merge order is not load order: who = %v, want from-bbb", psOut["who"])
+	}
+}
+
+// TestMergeOrderIsDeterministic: goroutine completion order must not leak into
+// the result. Running Fire repeatedly must always yield the same payload, or a
+// gateway's behaviour changes run to run with the same plugins installed.
+func TestMergeOrderIsDeterministic(t *testing.T) {
+	// The plugins differ in cost so a scheduler-dependent merge is visible.
+	slow := `
+local p = { name = "aaa" }
+p.state = { n = 0 }
+p.hooks = { request_end = "slow" }
+function p.slow(payload)
+  local acc = 0
+  for i = 1, 3000 do acc = acc + i % 7 end
+  p.state.n = p.state.n + 1
+  return { winner = "aaa", acc = acc }
+end
+return p
+`
+	fast := `
+local p = { name = "bbb" }
+p.state = { n = 0 }
+p.hooks = { request_end = "fast" }
+function p.fast(payload)
+  p.state.n = p.state.n + 1
+  return { winner = "bbb" }
+end
+return p
+`
+	ps := twoHookPlugins(t, slow, fast)
+	first := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m"})["winner"]
+	for i := 0; i < 60; i++ {
+		got := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m"})["winner"]
+		if got != first {
+			t.Fatalf("★ winner changed between runs: %q then %q — merge depends on goroutine "+
+				"scheduling, so the same configuration behaves differently run to run", first, got)
+		}
+	}
+	// Load order decides: bbb is loaded second, so it wins.
+	if first != "bbb" {
+		t.Errorf("winner = %q, want bbb (load order decides, not timing)", first)
+	}
+}
+
+// TestThrowingHookDoesNotBreakSiblings covers the failure path that golua
+// actually produces: a hook raising a Lua error.
+//
+// The test name used to claim it covered panics, and it used error() to do it.
+// Probing the six ways a Lua program can fault (error(), indexing nil, calling
+// nil, concatenating nil, arithmetic on nil, unbounded recursion) showed golua
+// converts ALL of them into an error RETURN, not a Go panic — so the recover()
+// in Fire was untested by that case, and deleting recover() still passed. The
+// test was renamed to say what it verifies.
+//
+// recover() is kept anyway: it guards the Go side of Fire (a nil map write, a
+// future change to how the payload is prepared), which is cheap and cannot be
+// triggered from Lua today. Claiming it is covered by a Lua test would be the
+// kind of assurance that evaporates the first time someone checks.
+func TestThrowingHookDoesNotBreakSiblings(t *testing.T) {
+	throwing := `
+local p = { name = "aaa" }
+p.state = {}
+p.hooks = { request_end = "boom" }
+function p.boom(payload) error("intentional failure") end
+return p
+`
+	healthy := counterPlugin("bbb", "")
+	ps := twoHookPlugins(t, throwing, healthy)
+
+	out := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m"}) // must not crash
+	if out == nil {
+		t.Error("Fire returned nil")
+	}
+	st, ok := ps.State("bbb").(map[string]interface{})
+	if !ok {
+		t.Fatal("healthy plugin has no state")
+	}
+	if n := st["n"]; n != float64(1) {
+		t.Errorf("★ healthy plugin did not run alongside the throwing one: n = %v", n)
+	}
+	he := ps.HookErrors()
+	if len(he) == 0 {
+		t.Error("a throwing hook was not recorded in hook_errors — the failure would be invisible")
+	}
+}
+
+// TestParallelHooksAllRunOnce: every plugin must be invoked exactly once per
+// Fire. A lost or duplicated goroutine shows up as a wrong total, which for the
+// billing plugin means a wrong bill.
+func TestParallelHooksAllRunOnce(t *testing.T) {
+	ps := twoHookPlugins(t, counterPlugin("aaa", ""), counterPlugin("bbb", ""))
+	const fires = 100
+	for i := 0; i < fires; i++ {
+		ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m"})
+	}
+	for _, name := range []string{"aaa", "bbb"} {
+		st, ok := ps.State(name).(map[string]interface{})
+		if !ok {
+			t.Fatalf("%s has no state", name)
+		}
+		if n := st["n"]; n != float64(fires) {
+			t.Errorf("%s counted %v hooks, want %d", name, n, fires)
+		}
+	}
+}
+
+// TestConcurrentFireIsSafe drives Fire from many goroutines at once. Each
+// plugin has its own Lua state and its own mutex, so this must hold; the race
+// detector is what proves it, not the assertions.
+func TestConcurrentFireIsSafe(t *testing.T) {
+	ps := twoHookPlugins(t, counterPlugin("aaa", ""), counterPlugin("bbb", ""))
+	var wg sync.WaitGroup
+	for g := 0; g < 8; g++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for i := 0; i < 50; i++ {
+				ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "source": "s"})
+			}
+		}()
+	}
+	wg.Wait()
+	for _, name := range []string{"aaa", "bbb"} {
+		st, ok := ps.State(name).(map[string]interface{})
+		if !ok {
+			t.Fatalf("%s has no state", name)
+		}
+		if n := st["n"]; n != float64(400) {
+			t.Errorf("%s counted %v, want 400", name, n)
+		}
+	}
+}
+
+// TestFireDoesNotHoldRegistryLockWhileRunningHooks: a hook that installs or
+// disables a plugin takes ps.mu for write. If Fire held ps.mu across the hook,
+// that would self-deadlock — the exact failure TrueAgent recorded for its own
+// parallel stop path.
+func TestFireDoesNotHoldRegistryLockWhileRunningHooks(t *testing.T) {
+	reentrant := `
+local p = { name = "aaa" }
+p.state = {}
+p.hooks = { request_end = "reenter" }
+function p.reenter(payload)
+  -- Reading the registry from inside a hook is the read half of the same lock.
+  local _ = #payload
+  return nil
+end
+return p
+`
+	vm := NewVM(filepath.Join(t.TempDir(), "adapters"))
+	if err := vm.Start(); err != nil {
+		t.Fatal(err)
+	}
+	defer vm.Stop()
+	ps := NewPlugins(vm, filepath.Join(t.TempDir(), "plugins"))
+	defer ps.Close()
+	ps.DisableStatePersistence()
+	if err := ps.LoadSource("aaa", reentrant); err != nil {
+		t.Fatal(err)
+	}
+	if err := ps.LoadSource("bbb", counterPlugin("bbb", "")); err != nil {
+		t.Fatal(err)
+	}
+
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m"})
+		// Touch the registry the way an admin request would, right after.
+		_ = ps.Count()
+		_ = ps.List()
+	}()
+	select {
+	case <-done:
+	case <-time.After(10 * time.Second):
+		t.Fatal("Fire deadlocked against the registry lock")
+	}
+}
+
+// TestBillingSurvivesParallelFire runs the REAL bundled plugin next to another
+// one. A synthetic counter cannot catch a mismatch between the documented
+// payload shape and what the plugin actually reads.
+func TestBillingSurvivesParallelFire(t *testing.T) {
+	dir := t.TempDir()
+	pdir := filepath.Join(dir, "plugins")
+	os.MkdirAll(pdir, 0o755)
+	src, err := os.ReadFile("plugins/billing.lua")
+	if err != nil {
+		t.Fatalf("read billing.lua: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(pdir, "billing.lua"), src, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(pdir, "observer.lua"),
+		[]byte(`local p={name="observer"} p.state={n=0}
+p.hooks={request_end="see"}
+function p.see(payload) p.state.n=p.state.n+1 return nil end
+return p`), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	vm := NewVM(filepath.Join(dir, "adapters"))
+	if err := vm.Start(); err != nil {
+		t.Fatal(err)
+	}
+	defer vm.Stop()
+	ps := NewPlugins(vm, pdir)
+	ps.save.setWakeDelayForTest(time.Millisecond)
+	defer ps.Close()
+	ps.DisableStatePersistence()
+	if err := ps.LoadDir(); err != nil {
+		t.Fatal(err)
+	}
+	if ps.Count() != 2 {
+		t.Fatalf("loaded %d plugins, want 2", ps.Count())
+	}
+
+	payload := map[string]interface{}{
+		"model": "deepseek-v4.1-flash", "source": "commandcode", "key": "k", "ok": true,
+		"usage": map[string]interface{}{
+			"prompt_tokens": float64(1000), "completion_tokens": float64(100),
+			"cache_hit_tokens": float64(0),
+		},
+	}
+	ps.Fire(StageRequestEnd, payload)
+
+	st := ps.State("billing")
+	if st == nil {
+		t.Fatal("billing produced no state")
+	}
+	m := st.(map[string]interface{})
+	total, ok := m["total"].(map[string]interface{})
+	if !ok {
+		t.Fatalf("billing.total is %T", m["total"])
+	}
+	if total["requests"] != float64(1) {
+		t.Errorf("billing counted %v requests, want 1 — the plugin was starved by the parallel path",
+			total["requests"])
+	}
+	if n := ps.State("observer").(map[string]interface{})["n"]; n != float64(1) {
+		t.Errorf("observer counted %v, want 1", n)
+	}
+	if len(ps.HookErrors()) != 0 {
+		t.Errorf("hook errors under parallel Fire: %v", ps.HookErrors())
+	}
+}

internal/lua/hook_guard_test.go

@@ -0,0 +1,76 @@
+package lua
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// A plugin hook that RAISES must not take the process down. This is the
+// production outage: a Lua error anywhere in a hook made golua's callEx call
+// L.StackTrace(), which calls lua_getinfo and SIGSEGVs on a deep enough stack —
+// a C-level signal Go cannot recover from, so one buggy plugin killed the whole
+// gateway and took every in-flight request with it.
+//
+// The fix routes hook calls through a Lua-side pcall guard, so the error comes
+// back as an ordinary return value. This test fires hooks that raise on purpose
+// and asserts three things: the process survives, the failure is RECORDED, and
+// a well-behaved plugin on the same state keeps working afterwards (the error
+// must not poison the Lua state).
+func TestHookThatRaisesDoesNotCrashTheProcess(t *testing.T) {
+	ps, pdir := billingVM(t)
+	boom := `
+local plugin = {}
+plugin.name = "boom"
+plugin.version = "0.1"
+function plugin.request_end(payload)
+  -- Raise on a table index, the exact shape of the billing bug that caused the
+  -- outage. Deliberately NOT a syntax error: this must load fine and fail only
+  -- when invoked.
+  local x = nil
+  return x.field
+end
+return plugin`
+	if err := os.WriteFile(filepath.Join(pdir, "boom.lua"), []byte(boom), 0644); err != nil {
+		t.Fatal(err)
+	}
+	if err := ps.LoadSource("boom", boom); err != nil {
+		t.Fatalf("load boom: %v", err)
+	}
+
+	payload := map[string]interface{}{
+		"model": "m", "source": "s", "ok": true,
+		"prompt_tokens": 100, "completion_tokens": 10, "time": 1750000000000,
+	}
+	// Fire many times: a single call could pass by luck, but if the error ever
+	// escapes into golua's C path the process dies and this test never returns.
+	for i := 0; i < 50; i++ {
+		ps.Fire(StageRequestEnd, payload)
+	}
+	// Reaching this line at all is the primary assertion.
+
+	errs := ps.HookErrors()
+	end, ok := errs[string(StageRequestEnd)]
+	if !ok {
+		t.Fatal("a raising hook left no record — failures must be observable, not swallowed")
+	}
+	if end["count"] == nil || end["count"].(int) == 0 {
+		t.Error("hook error count is zero despite 50 raising calls")
+	}
+	msg, _ := end["last_error"].(string)
+	if !strings.Contains(msg, "boom") {
+		t.Errorf("last_error does not name the offending plugin: %q", msg)
+	}
+
+	// The billing plugin shares the same Plugins registry and must still work:
+	// one broken plugin may not disable the others.
+	st, _ := ps.State("billing").(map[string]interface{})
+	if st == nil || st["total"] == nil {
+		t.Fatalf("the healthy plugin stopped working after another plugin raised")
+	}
+	tot, _ := st["total"].(map[string]interface{})
+	if tot == nil || tot["requests"] == nil || tot["requests"].(float64) == 0 {
+		t.Errorf("billing recorded no requests after the raising plugin ran: %v", st["total"])
+	}
+}

internal/lua/persist_test.go

@@ -0,0 +1,283 @@
+package lua
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+// These cover plugin state persistence: a plugin's totals live in the Lua VM,
+// which dies with the process. Measured on the real gateway before this change:
+// 218,241 requests and 26.2M prompt tokens gone after one systemctl restart.
+
+func persistTestPlugin() string {
+	return `
+local plugin = { name = "counter", version = "1.0" }
+plugin.state = { n = 0, prices_seen = 0 }
+plugin.prices = { rate = 1 }
+plugin.hooks = { request_end = "bump" }
+function plugin.bump(payload)
+  plugin.state.n = plugin.state.n + 1
+  return nil
+end
+return plugin
+`
+}
+
+// newPersistVM wires a plugin registry on a fresh dir, mirroring newPluginVM.
+func newPersistVM(t *testing.T) (*Plugins, string) {
+	t.Helper()
+	dir := t.TempDir()
+	vm := NewVM(filepath.Join(dir, "adapters"))
+	if err := vm.Start(); err != nil {
+		t.Fatalf("vm start: %v", err)
+	}
+	t.Cleanup(vm.Stop)
+	pdir := filepath.Join(dir, "plugins")
+	ps := NewPlugins(vm, pdir)
+	// Shorten the saver debounce: Close() waits for the saver goroutine, so
+	// with the production 2s interval every test would pay 2s on teardown.
+	ps.save.setWakeDelayForTest(2 * time.Millisecond)
+	t.Cleanup(ps.Close)
+	return ps, pdir
+}
+
+func loadCounter(t *testing.T, ps *Plugins) {
+	t.Helper()
+	if err := ps.LoadSource("counter", persistTestPlugin()); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+}
+
+func stateN(t *testing.T, ps *Plugins) float64 {
+	t.Helper()
+	st := ps.State("counter")
+	m, ok := st.(map[string]interface{})
+	if !ok {
+		t.Fatalf("state is %T, want map", st)
+	}
+	n, ok := m["n"].(float64)
+	if !ok {
+		t.Fatalf("state.n is %T, want float64", m["n"])
+	}
+	return n
+}
+
+// TestStateSurvivesRestart is the defect itself: a rebuilt registry over the
+// same plugin dir must come up with the previous totals, not at zero.
+func TestStateSurvivesRestart(t *testing.T) {
+	ps, pdir := newPersistVM(t)
+	loadCounter(t, ps)
+	for i := 0; i < 25; i++ {
+		ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "source": "s"})
+	}
+	if got := stateN(t, ps); got != 25 {
+		t.Fatalf("in-process total = %v, want 25", got)
+	}
+	// Force the write the saver would do, so the test does not depend on timing.
+	ps.save.flush()
+	ps.Close()
+
+	// A brand-new registry over the same dir: this is the restart.
+	vm := NewVM(filepath.Join(t.TempDir(), "adapters"))
+	if err := vm.Start(); err != nil {
+		t.Fatal(err)
+	}
+	defer vm.Stop()
+	ps2 := NewPlugins(vm, pdir)
+	defer ps2.Close()
+	loadCounter(t, ps2)
+
+	if got := stateN(t, ps2); got != 25 {
+		t.Fatalf("★ total after restart = %v, want 25 — this is the 'restart loses the books' bug", got)
+	}
+}
+
+// TestPricesAndStateAreSeparate: restoring configuration over history (or the
+// reverse) would either erase the totals or resurrect stale prices.
+func TestPricesAndStateAreSeparate(t *testing.T) {
+	ps, pdir := newPersistVM(t)
+	loadCounter(t, ps)
+	for i := 0; i < 7; i++ {
+		ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "source": "s"})
+	}
+	ps.save.flush()
+	ps.Close()
+
+	b, err := os.ReadFile(ps.stateFile("counter"))
+	if err != nil {
+		t.Fatalf("no state file: %v", err)
+	}
+	var saved struct {
+		State  map[string]interface{} `json:"state"`
+		Prices map[string]interface{} `json:"prices"`
+	}
+	if err := json.Unmarshal(b, &saved); err != nil {
+		t.Fatalf("state file is not valid JSON: %v", err)
+	}
+	if saved.Prices == nil || saved.Prices["rate"] != float64(1) {
+		t.Errorf("prices were not persisted separately: %v", saved.Prices)
+	}
+	if saved.State["n"] != float64(7) {
+		t.Errorf("state.n = %v, want 7", saved.State["n"])
+	}
+	_ = pdir
+}
+
+// TestPricesOnlyUpdatePersists guards a real hole: SetState returns early for a
+// prices-only payload (correctly leaving state alone), and the first version
+// returned before the persistence write — so a reprice was durable in memory
+// only and a restart silently reverted to the old prices.
+func TestPricesOnlyUpdatePersists(t *testing.T) {
+	ps, _ := newPersistVM(t)
+	loadCounter(t, ps)
+	for i := 0; i < 5; i++ {
+		ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "source": "s"})
+	}
+	ps.save.flush()
+
+	err := ps.SetState("counter", map[string]interface{}{
+		"prices": map[string]interface{}{"rate": 42},
+	})
+	if err != nil {
+		t.Fatalf("SetState: %v", err)
+	}
+	if got := stateN(t, ps); got != 5 {
+		t.Errorf("a prices-only payload must not touch state: n = %v, want 5", got)
+	}
+
+	b, err := os.ReadFile(ps.stateFile("counter"))
+	if err != nil {
+		t.Fatalf("no state file after a prices-only update: %v", err)
+	}
+	var saved struct {
+		State  map[string]interface{} `json:"state"`
+		Prices map[string]interface{} `json:"prices"`
+	}
+	if err := json.Unmarshal(b, &saved); err != nil {
+		t.Fatal(err)
+	}
+	if saved.Prices["rate"] != float64(42) {
+		t.Errorf("★ new price not persisted: %v — a restart would revert to the old price", saved.Prices)
+	}
+	if saved.State["n"] != float64(5) {
+		t.Errorf("state was clobbered by a price change: %v", saved.State["n"])
+	}
+}
+
+// TestHookReturnValueSurvivesSnapshot guards the ordering bug: snapshotting
+// plugin.state resets the Lua stack, so doing it BEFORE reading the hook's
+// return value silently turned every opinionated plugin into a silent one —
+// breaking the documented "return a table to merge into payload" contract with
+// no error anywhere.
+func TestHookReturnValueSurvivesSnapshot(t *testing.T) {
+	ps, _ := newPersistVM(t)
+	code := `
+local plugin = { name = "opinionated" }
+plugin.state = { n = 0 }
+plugin.hooks = { request_end = "tag" }
+function plugin.tag(payload)
+  plugin.state.n = plugin.state.n + 1
+  return { cost_usd = 1.25, verdict = "billed" }
+end
+return plugin
+`
+	if err := ps.LoadSource("opinionated", code); err != nil {
+		t.Fatal(err)
+	}
+	out := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "source": "s"})
+	if out["cost_usd"] != 1.25 {
+		t.Errorf("★ hook return value lost: payload = %v", out)
+	}
+	if out["verdict"] != "billed" {
+		t.Errorf("merged field lost: %v", out)
+	}
+	ps.save.flush()
+	st := ps.State("opinionated").(map[string]interface{})
+	if st["n"] != float64(1) {
+		t.Errorf("state.n = %v, want 1 (the hook still ran)", st["n"])
+	}
+}
+
+// TestCorruptStateFileIsNotFatal: a truncated write must degrade to compiled-in
+// defaults, never to a gateway that refuses to start.
+func TestCorruptStateFileIsNotFatal(t *testing.T) {
+	ps, _ := newPersistVM(t)
+	loadCounter(t, ps)
+	for i := 0; i < 3; i++ {
+		ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "source": "s"})
+	}
+	ps.save.flush()
+	ps.Close()
+
+	if err := os.WriteFile(ps.stateFile("counter"), []byte("{not json"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	vm := NewVM(filepath.Join(t.TempDir(), "adapters"))
+	if err := vm.Start(); err != nil {
+		t.Fatal(err)
+	}
+	defer vm.Stop()
+	ps2 := NewPlugins(vm, ps.dir)
+	defer ps2.Close()
+	var warned bool
+	ps2.logf = func(string, ...interface{}) { warned = true }
+	loadCounter(t, ps2)
+
+	if got := stateN(t, ps2); got != 0 {
+		t.Errorf("with a corrupt file the plugin must fall back to its defaults, got n = %v", got)
+	}
+	if !warned {
+		t.Error("a corrupt state file must warn the operator, not fail silently")
+	}
+	// And it must still forward.
+	ps2.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "source": "s"})
+}
+
+// TestFlushIsCoalesced: N mutations must not become N writes. A synchronous
+// per-request write would put a file write on the hot path.
+func TestFlushIsCoalesced(t *testing.T) {
+	ps, _ := newPersistVM(t)
+	loadCounter(t, ps)
+	for i := 0; i < 500; i++ {
+		ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "source": "s"})
+	}
+	ps.save.flush()
+	// 500 mutations must collapse to a handful of writes, not 500. The bound is
+	// loose on purpose: the saver also flushes on a timer, so how many writes
+	// happen during the loop depends on how long 500 hook calls take. What must
+	// never happen is one write per mutation.
+	if w := ps.save.writes.Load(); w > 5 {
+		t.Errorf("500 hook calls produced %d file writes; the saver must coalesce", w)
+	}
+	if got := stateN(t, ps); got != 500 {
+		t.Fatalf("n = %v, want 500", got)
+	}
+}
+
+// TestCloseFlushesTail: the shutdown path must not lose the last interval,
+// which would reintroduce the same defect in a smaller window.
+func TestCloseFlushesTail(t *testing.T) {
+	ps, _ := newPersistVM(t)
+	loadCounter(t, ps)
+	ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "source": "s"})
+	ps.Close()
+	// Close() already waits for the final flush; no sleep needed.
+
+	b, err := os.ReadFile(ps.stateFile("counter"))
+	if err != nil {
+		t.Fatalf("★ Close() did not flush: %v — a shutdown loses the tail", err)
+	}
+	var saved struct {
+		State map[string]interface{} `json:"state"`
+	}
+	if err := json.Unmarshal(b, &saved); err != nil {
+		t.Fatal(err)
+	}
+	if saved.State["n"] != float64(1) {
+		t.Errorf("flushed n = %v, want 1", saved.State["n"])
+	}
+}

internal/lua/plugins_test.go

@@ -0,0 +1,377 @@
+package lua
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// newPluginVM builds a VM plus a plugin registry rooted at dir.
+func newPluginVM(t *testing.T) (*VM, *Plugins, string) {
+	t.Helper()
+	dir := filepath.Join(t.TempDir(), "adapters")
+	vm := NewVM(dir)
+	if err := vm.Start(); err != nil {
+		t.Fatalf("vm start: %v", err)
+	}
+	t.Cleanup(vm.Stop)
+	pdir := filepath.Join(t.TempDir(), "plugins")
+	return vm, NewPlugins(vm, pdir), pdir
+}
+
+// loadPlugin writes one plugin to disk and loads it.
+func loadPlugin(t *testing.T, ps *Plugins, name, code string) error {
+	t.Helper()
+	if err := os.MkdirAll(ps.dir, 0755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(ps.dir, name+".lua"), []byte(code), 0644); err != nil {
+		t.Fatal(err)
+	}
+	return ps.LoadSource(name, code)
+}
+
+// TestPluginManifestAndHooks: the two hook registration forms both work and the
+// manifest is read.
+func TestPluginManifestAndHooks(t *testing.T) {
+	_, ps, _ := newPluginVM(t)
+	code := `
+local p = {}
+p.name = "demo"
+p.version = "1.2.3"
+p.description = "a demo plugin"
+p.author = "tester"
+p.hooks = { request_end = "on_end" }
+function p.on_end(payload)
+  payload.seen = true
+  payload.name_seen = "demo"
+  return payload
+end
+return p
+`
+	if err := loadPlugin(t, ps, "demo", code); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	list := ps.List()
+	if len(list) != 1 {
+		t.Fatalf("List() = %d plugins, want 1", len(list))
+	}
+	if list[0]["name"] != "demo" || list[0]["version"] != "1.2.3" {
+		t.Errorf("manifest not read: %+v", list[0])
+	}
+	hooks := list[0]["hooks"].([]string)
+	if len(hooks) != 1 || hooks[0] != string(StageRequestEnd) {
+		t.Errorf("hooks = %v, want [request_end]", hooks)
+	}
+	out := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m"})
+	if out["seen"] != true || out["name_seen"] != "demo" {
+		t.Errorf("hook did not mutate payload: %+v", out)
+	}
+}
+
+// TestPluginAnonymousHookForm: `request_end = function() end` directly on the
+// table must register too, since a single-hook plugin should not need a name.
+func TestPluginAnonymousHookForm(t *testing.T) {
+	_, ps, _ := newPluginVM(t)
+	code := `
+local p = { name = "anon" }
+p.request_end = function(payload)
+  payload.hit = 1
+  return payload
+end
+return p
+`
+	if err := loadPlugin(t, ps, "anon", code); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	out := ps.Fire(StageRequestEnd, map[string]interface{}{})
+	if out["hit"] != float64(1) {
+		t.Errorf("anonymous hook did not fire: %+v", out)
+	}
+}
+
+// TestPluginHookStagesFireInOrder: each stage reaches only its own hooks.
+func TestPluginHookStagesFireInOrder(t *testing.T) {
+	_, ps, _ := newPluginVM(t)
+	code := `
+local p = { name = "stages" }
+p.hooks = {
+  request_start = "s1",
+  routed = "s2",
+  request_end = "s3",
+}
+function p.s1(x) x.order = (x.order or "") .. "1" return x end
+function p.s2(x) x.order = (x.order or "") .. "2" return x end
+function p.s3(x) x.order = (x.order or "") .. "3" return x end
+return p
+`
+	if err := loadPlugin(t, ps, "stages", code); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	payload := map[string]interface{}{}
+	ps.Fire(StageRequestStart, payload)
+	ps.Fire(StageRouted, payload)
+	ps.Fire(StageRequestEnd, payload)
+	if payload["order"] != "123" {
+		t.Errorf("stage order = %v, want \"123\"", payload["order"])
+	}
+}
+
+// TestPluginErrorIsContained is the critical safety property: a throwing hook
+// must not propagate. Forwarding depends on it.
+func TestPluginErrorIsContained(t *testing.T) {
+	_, ps, _ := newPluginVM(t)
+	code := `
+local p = { name = "boom" }
+p.hooks = { request_end = "kaboom" }
+function p.kaboom(payload)
+  error("intentional plugin failure")
+end
+return p
+`
+	if err := loadPlugin(t, ps, "boom", code); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	// Must not panic and must return the payload unchanged.
+	out := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m"})
+	if out["model"] != "m" {
+		t.Errorf("payload was altered by a failing plugin: %+v", out)
+	}
+	// And the failure must be visible, not silent.
+	errs := ps.HookErrors()
+	if errs["request_end"] == nil {
+		t.Error("a failing plugin left no error record; it would be silently missing")
+	}
+}
+
+// TestPluginFailingHookDoesNotBlockLaterPlugins: one bad plugin must not stop
+// the next one from running.
+func TestPluginFailingHookDoesNotBlockLaterPlugins(t *testing.T) {
+	_, ps, _ := newPluginVM(t)
+	bad := `
+local p = { name = "bad" }
+p.hooks = { request_end = "f" }
+function p.f(x) error("boom") end
+return p
+`
+	good := `
+local p = { name = "good" }
+p.hooks = { request_end = "f" }
+function p.f(x) x.good = true return x end
+return p
+`
+	_ = loadPlugin(t, ps, "bad", bad)
+	if err := loadPlugin(t, ps, "good", good); err != nil {
+		t.Fatalf("load good: %v", err)
+	}
+	out := ps.Fire(StageRequestEnd, map[string]interface{}{})
+	if out["good"] != true {
+		t.Errorf("a good plugin was blocked by a failing one: %+v", out)
+	}
+}
+
+// TestPluginSyntaxErrorIsIsolated: a plugin that will not compile is listed
+// with its error and is never called — it must not prevent LoadDir from loading
+// the rest.
+func TestPluginSyntaxErrorIsIsolated(t *testing.T) {
+	_, ps, _ := newPluginVM(t)
+	broken := "this is not lua((("
+	good := `
+local p = { name = "ok" }
+p.hooks = { request_end = "f" }
+function p.f(x) x.ok = true return x end
+return p
+`
+	_ = loadPlugin(t, ps, "broken", broken)
+	if err := loadPlugin(t, ps, "ok", good); err != nil {
+		t.Fatalf("load ok: %v", err)
+	}
+	if err := ps.LoadDir(); err != nil {
+		t.Fatalf("LoadDir: %v", err)
+	}
+	// The broken plugin must not be callable and must carry an error.
+	for _, row := range ps.List() {
+		if row["name"] == "broken" {
+			if row["loaded"] == true {
+				t.Error("a plugin with a syntax error reported itself as loaded")
+			}
+			if row["error"] == nil || row["error"] == "" {
+				t.Error("a broken plugin carries no error message")
+			}
+		}
+	}
+	// The good plugin still works.
+	out := ps.Fire(StageRequestEnd, map[string]interface{}{})
+	if out["ok"] != true {
+		t.Errorf("good plugin stopped working: %+v", out)
+	}
+}
+
+// TestPluginUIExtension: a plugin can contribute a page and elements.
+func TestPluginUIExtension(t *testing.T) {
+	_, ps, _ := newPluginVM(t)
+	code := `
+local p = { name = "ui" }
+p.hooks = { request_end = "f" }
+function p.f(x) return x end
+p.ui = {
+  page = {
+    page_id = "billing",
+    title = "Billing",
+    icon = "💰",
+    order = 50,
+    mount = "<div id=billing>hi</div><script>console.log('m')</script>",
+  },
+  elements = {
+    { target = "status", anchor = "top", mount = "<div>cost</div>" },
+  },
+}
+return p
+`
+	if err := loadPlugin(t, ps, "ui", code); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	// Every contributed page — including the single `page` field — is folded
+	// into one merged list. Reading ui.Page here would silently pass on a
+	// payload whose pages were all dropped.
+	ui := ps.UI()
+	if len(ui.Pages) != 1 {
+		t.Fatalf("expected 1 merged page, got %d", len(ui.Pages))
+	}
+	pg := ui.Pages[0]
+	if pg.PageID != "billing" || pg.Title != "Billing" {
+		t.Errorf("page = %+v", pg)
+	}
+	if !strings.Contains(pg.Mount, "console.log") {
+		t.Error("mount lost its script content")
+	}
+	if len(ui.Elements) != 1 || ui.Elements[0].Target != "status" {
+		t.Errorf("elements = %+v", ui.Elements)
+	}
+}
+
+// TestPluginHookReturnsNilIsNoOpinion: a hook returning nothing must leave the
+// payload untouched (plugins should not be forced to echo it back).
+func TestPluginHookReturnsNilIsNoOpinion(t *testing.T) {
+	_, ps, _ := newPluginVM(t)
+	code := `
+local p = { name = "silent" }
+p.hooks = { request_end = "f" }
+function p.f(payload)
+  -- records nothing, returns nothing
+  return nil
+end
+return p
+`
+	if err := loadPlugin(t, ps, "silent", code); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	out := ps.Fire(StageRequestEnd, map[string]interface{}{"model": "m", "ok": true})
+	if out["model"] != "m" || out["ok"] != true {
+		t.Errorf("a no-op hook disturbed the payload: %+v", out)
+	}
+}
+
+// TestPluginUIJSONShape is a wire-format guard: the kernel sends this to the
+// browser, so the shape is a contract with the WebUI.
+func TestPluginUIJSONShape(t *testing.T) {
+	_, ps, _ := newPluginVM(t)
+	code := `
+local p = { name = "shape" }
+p.hooks = { request_end = "f" }
+function p.f(x) return x end
+p.ui = { elements = { { target = "keys", mount = "<b>k</b>" } } }
+return p
+`
+	if err := loadPlugin(t, ps, "shape", code); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	b, err := json.Marshal(ps.UI())
+	if err != nil {
+		t.Fatalf("marshal UI: %v", err)
+	}
+	var view struct {
+		Elements []struct {
+			Target string `json:"target"`
+			Mount  string `json:"mount"`
+		} `json:"elements"`
+	}
+	if err := json.Unmarshal(b, &view); err != nil {
+		t.Fatalf("unmarshal: %v", err)
+	}
+	if len(view.Elements) != 1 || view.Elements[0].Target != "keys" {
+		t.Errorf("UI JSON shape = %+v", view.Elements)
+	}
+}
+
+// TestPluginFireWithNoPluginsIsNoop: an empty registry must not allocate or fail.
+func TestPluginFireWithNoPluginsIsNoop(t *testing.T) {
+	_, ps, _ := newPluginVM(t)
+	in := map[string]interface{}{"a": 1}
+	out := ps.Fire(StageRequestEnd, in)
+	if out["a"] != 1 || ps.Count() != 0 {
+		t.Errorf("empty registry misbehaved: %+v", out)
+	}
+}
+
+// TestChainStepIsARealStage: chain_step is documented as a distinct stage that
+// fires once per step of an AUTO walk. If it were only a field on `routed`, a
+// plugin author following the docs would silently get one event instead of the
+// whole walk.
+func TestChainStepIsARealStage(t *testing.T) {
+	found := false
+	for _, s := range AllStages {
+		if s == StageChainStep {
+			found = true
+		}
+	}
+	if !found {
+		t.Fatal("StageChainStep is not in AllStages, so the dispatcher never registers it")
+	}
+	// Ordering: it must sit between request_start and routed, which is what
+	// docs/plugins.md promises.
+	var iStart, iStep, iRouted = -1, -1, -1
+	for i, s := range AllStages {
+		switch s {
+		case StageRequestStart:
+			iStart = i
+		case StageChainStep:
+			iStep = i
+		case StageRouted:
+			iRouted = i
+		}
+	}
+	if !(iStart < iStep && iStep < iRouted) {
+		t.Errorf("stage order = %v, want request_start < chain_step < routed", AllStages)
+	}
+	_, ps, _ := newPluginVM(t)
+	code := `
+local p = { name = "stepper" }
+p.hooks = { chain_step = "s" }
+function p.s(payload)
+  payload.kinds = (payload.kinds or "")
+  return nil
+end
+return p
+`
+	if err := loadPlugin(t, ps, "stepper", code); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	// It must actually dispatch.
+	seen := false
+	for _, row := range ps.List() {
+		if row["name"] == "stepper" {
+			hooks := row["hooks"].([]string)
+			for _, h := range hooks {
+				if h == string(StageChainStep) {
+					seen = true
+				}
+			}
+		}
+	}
+	if !seen {
+		t.Error("a plugin registered for chain_step is not reported as such")
+	}
+}

internal/lua/vm.go

@@ -36,7 +36,7 @@ import (
 	golua "github.com/aarzilli/golua/lua"
 )
 
-//go:embed adapters/*.lua
+//go:embed adapters/*.lua plugins/*.lua
 var bundledAdapters embed.FS
 
 // adapterGlobal is the reserved global holding the adapter table after the
@@ -103,6 +103,11 @@ type adapterPool struct {
 	lastGrow   time.Time
 	idleRounds int // consecutive janitor rounds that saw reclaimable slack
 	peakInUse  int // high-water mark of inUse, for observability
+	// pluginMode makes boot() store the returned table under pluginGlobal
+	// instead of adapterGlobal. Everything else (elastic sizing, reclaim) is
+	// identical, which is why plugins reuse this pool rather than getting a
+	// second implementation.
+	pluginMode bool
 }
 
 const (
@@ -116,6 +121,13 @@ const (
 	// growCooldown keeps a burst of misses from batching repeatedly while the
 	// previous batch is still booting.
 	growCooldown = time.Second
+	// maxPluginStates caps how many concurrent VM states ONE plugin may occupy.
+	// A plugin is third-party code on the request path, so its ceiling is much
+	// lower than an adapter's (which is sized from the sources'
+	// max_concurrent): a plugin hook is a short synchronous call, so a handful
+	// of states is already far more parallelism than any real hook needs, and a
+	// runaway plugin cannot balloon memory the way a per-source adapter pool can.
+	maxPluginStates = 4
 	// residentWorkers is how many states an adapter keeps warm once it has
 	// served at least one request. Booting is milliseconds, but keeping one warm
 	// removes that from the critical path of the next request. Adapters that
@@ -265,7 +277,14 @@ func (p *adapterPool) boot() (*worker, error) {
 		L.Close()
 		return nil, fmt.Errorf("adapter %s must return a table", p.name)
 	}
-	L.SetGlobal(adapterGlobal)
+	// SetGlobal POPS the value off the stack, so it can only be called once per
+	// boot. Plugins therefore store under pluginGlobal only, and NOT under
+	// adapterGlobal: a second SetGlobal on the now-empty stack would assign nil.
+	if p.pluginMode {
+		L.SetGlobal(pluginGlobal)
+	} else {
+		L.SetGlobal(adapterGlobal)
+	}
 	L.SetTop(0)
 	return &worker{L: L}, nil
 }
@@ -601,6 +620,55 @@ func (v *VM) Start() error {
 	return nil
 }
 
+// bundledPluginsDir is the directory inside the embedded FS holding the
+// plugins shipped with the gateway. It is separate from adapters/ on purpose:
+// the two are loaded by different machinery into different kinds of Lua state
+// (a protocol transform vs. request-pipeline hooks), and keeping them apart
+// makes it obvious that dropping a file in one does not affect the other.
+const bundledPluginsDir = "plugins"
+
+// ReadBundledPlugin returns the source of a plugin shipped with the gateway.
+// It exists so a test (or an operator tool) can load a bundled plugin without
+// depending on whether seeding has already run for this directory.
+func ReadBundledPlugin(name string) (string, error) {
+	data, err := bundledAdapters.ReadFile(bundledPluginsDir + "/" + name + ".lua")
+	if err != nil {
+		return "", fmt.Errorf("bundled plugin %s: %w", name, err)
+	}
+	return string(data), nil
+}
+
+// writeBundledPlugins seeds the plugin directory with the shipped plugins.
+//
+// It runs only when the directory does not exist yet (same rule as adapters):
+// once the directory exists it is authoritative, so deleting a shipped plugin is
+// a real delete and editing one survives restarts.
+func writeBundledPlugins(dir string) error {
+	if dir == "" {
+		return nil
+	}
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return fmt.Errorf("mkdir plugin dir: %w", err)
+	}
+	entries, err := bundledAdapters.ReadDir(bundledPluginsDir)
+	if err != nil {
+		return nil // nothing embedded; not an error
+	}
+	for _, e := range entries {
+		if e.IsDir() || filepath.Ext(e.Name()) != ".lua" {
+			continue
+		}
+		data, err := bundledAdapters.ReadFile(bundledPluginsDir + "/" + e.Name())
+		if err != nil {
+			continue
+		}
+		if err := os.WriteFile(filepath.Join(dir, e.Name()), data, 0644); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func (v *VM) Stop() {
 	select {
 	case <-v.janitorStop:
@@ -925,9 +993,47 @@ func restorePcall(L *golua.State) {
 	}
 }
 
+// hookGuardName is the Lua global that wraps every plugin hook call.
+const hookGuardName = "__llmsproxy_call_hook"
+
+// hookGuardSrc defines the wrapper. It exists because of a hard constraint in
+// the binding: golua's callEx calls L.StackTrace() on ANY pcall error, and
+// StackTrace() calls lua_getinfo, which SIGSEGVs in this LuaJIT build once the
+// stack is deep enough (a request_end payload with the AUTO chain trace does
+// it). Go cannot recover from a C-level signal, so a single Lua mistake inside
+// one plugin killed the whole gateway — the production outage this was written
+// for. Repeated crashes proved the boundary is not theoretical.
+//
+// pcall INSIDE Lua catches the error before golua ever sees a non-zero
+// pcall status, so the C stack-trace path is never entered. The failure comes
+// back as an ordinary (nil, message) pair, which the Go side records in
+// hook_errors and moves on from — the documented contract that "a broken plugin
+// must not affect request forwarding" finally holds for script errors too, not
+// just for Go panics.
+//
+//	returns: (result, errorMessage) — both nil/"" on success.
+const hookGuardSrc = `
+function ` + hookGuardName + `(fn, payload)
+  local ok, res = pcall(fn, payload)
+  if not ok then
+    return nil, tostring(res)
+  end
+  return res, nil
+end`
+
+func registerHookGuard(L *golua.State) {
+	if err := L.DoString(hookGuardSrc); err != nil {
+		// Nothing useful to do here beyond leaving the global absent: invoke()
+		// checks for it and falls back to a direct call, which still works for
+		// correct plugins (only their ERRORS stop being survivable).
+		L.Pop(1)
+	}
+}
+
 func setupGlobals(L *golua.State) {
 	restorePcall(L)
 	buildJSONTable(L)
+	registerHookGuard(L)
 
 	registerFn(L, "hmac_sha256_hex", func(L *golua.State) int {
 		key := L.ToString(1)
@@ -1104,6 +1210,56 @@ func pushGoValue(L *golua.State, v interface{}) {
 }
 
 func jsonEncode(v interface{}) ([]byte, error) { return json.Marshal(v) }
+
+// luaToJSON converts the Lua value at idx into a Go value via json.encode, then
+// unmarshals it into out. It is the bridge used by the plugin manifest/UI
+// reader: the plugin returns a plain Lua table, and Go wants a typed struct.
+//
+// It goes through JSON rather than walking the Lua stack directly because the
+// adapter/plugin boundary already speaks JSON everywhere else (transform_request
+// gets a JSON string, hooks get a JSON string), so this keeps one representation
+// instead of two.
+func luaToJSON(L *golua.State, idx int, out interface{}) error {
+	if L.GetTop() < 1 {
+		return fmt.Errorf("empty stack")
+	}
+	abs := idx
+	if abs < 0 {
+		abs = L.GetTop() + 1 + abs
+	}
+	if abs < 1 || abs > L.GetTop() {
+		return fmt.Errorf("index %d out of range (top=%d)", idx, L.GetTop())
+	}
+	// Absolute indices throughout: this binding aborts the process (SIGABRT)
+	// on a bad index rather than panicking, so the stack is captured before any
+	// push instead of being addressed relative to a shifting top.
+	//
+	// json.encode is pushed onto the stack and the value is pushed AFTER it, so
+	// Call(1, 1) invokes it (Call takes no function index — it calls whatever
+	// sits below the nargs values).
+	L.GetGlobal("json")
+	if L.IsNil(-1) {
+		L.SetTop(0)
+		return fmt.Errorf("json global missing")
+	}
+	L.GetField(-1, "encode")
+	if L.Type(-1) != golua.LUA_TFUNCTION {
+		L.SetTop(0)
+		return fmt.Errorf("json.encode missing")
+	}
+	L.PushValue(abs)
+	if err := L.Call(1, 1); err != nil {
+		L.SetTop(0)
+		return err
+	}
+	if L.GetTop() < 1 || L.Type(-1) != golua.LUA_TSTRING {
+		L.SetTop(0)
+		return fmt.Errorf("json.encode did not return a string")
+	}
+	s := L.ToString(-1)
+	L.SetTop(0)
+	return json.Unmarshal([]byte(s), out)
+}
 func jsonDecode(s string) (interface{}, error) {
 	var v interface{}
 	if err := json.Unmarshal([]byte(s), &v); err != nil {

internal/provider/gemini_endpoint_test.go

@@ -0,0 +1,270 @@
+package provider
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"path/filepath"
+	"strings"
+	"sync"
+	"testing"
+
+	"llmsproxy/internal/config"
+	"llmsproxy/internal/lua"
+	"llmsproxy/internal/types"
+)
+
+// Gemini is the only adapter whose endpoint carries the model in the PATH
+// (POST /v1beta/models/{model}:generateContent), so it is the only one that
+// needs the substitution this file covers.
+//
+// The defect it fixes was silent: the adapter shipped endpoint="/v1/models",
+// which is Gemini's model-LIST endpoint and answers 405 to POST, so the preset
+// template produced a source that could never work.
+
+func geminiVM(t *testing.T) *lua.VM {
+	t.Helper()
+	// The dir must be named "adapters": the VM seeds its bundled adapters into
+	// <dir> on Start and a differently-named dir leaves it empty, which surfaces
+	// as "adapter gemini not loaded" rather than an obvious setup error.
+	vm := lua.NewVM(filepath.Join(t.TempDir(), "adapters"))
+	if err := vm.Start(); err != nil {
+		t.Fatalf("lua vm: %v", err)
+	}
+	t.Cleanup(vm.Stop)
+	return vm
+}
+
+// geminiProvider builds a provider on the gemini adapter against base.
+func geminiProvider(t *testing.T, base string, models ...string) *Provider {
+	t.Helper()
+	if len(models) == 0 {
+		models = []string{"gemini-3.6-flash"}
+	}
+	ms := make([]config.Model, 0, len(models))
+	for _, m := range models {
+		ms = append(ms, config.Model{ID: m, Kind: "chat"})
+	}
+	return New(config.Source{
+		Name:          "gem",
+		BaseURL:       base,
+		Adapter:       "gemini",
+		APIKey:        "k",
+		MaxConcurrent: 4,
+		Models:        ms,
+	}, geminiVM(t))
+}
+
+// geminiRecorder captures the path the gateway actually requested and replies
+// with a minimal Gemini-shaped payload.
+type geminiRecorder struct {
+	mu     sync.Mutex
+	paths  []string
+	bodies []string
+	stream bool
+}
+
+func (g *geminiRecorder) handler(t *testing.T) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		raw, _ := io.ReadAll(r.Body)
+		g.mu.Lock()
+		// RequestURI, not URL.Path: URL.Path is the DECODED path, so an escaped
+		// %2F looks like a real "/" and the assertion could not tell an escaped
+		// id from an unescaped one.
+		g.paths = append(g.paths, r.RequestURI)
+		g.bodies = append(g.bodies, string(raw))
+		stream := g.stream
+		g.mu.Unlock()
+
+		if stream {
+			w.Header().Set("Content-Type", "text/event-stream")
+			w.WriteHeader(200)
+			fmt.Fprintf(w, "data: %s\n\n", `{"candidates":[{"content":{"parts":[{"text":"hi"}]},"finishReason":"STOP"}],"usageMetadata":{"promptTokenCount":3,"candidatesTokenCount":1,"totalTokenCount":4}}`)
+			fmt.Fprintln(w, "data: [DONE]")
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprint(w, `{"candidates":[{"content":{"parts":[{"text":"pong"}]},"finishReason":"STOP"}],"usageMetadata":{"promptTokenCount":3,"candidatesTokenCount":1,"totalTokenCount":4}}`)
+	}
+}
+
+func (g *geminiRecorder) lastPath() string {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	if len(g.paths) == 0 {
+		return ""
+	}
+	return g.paths[len(g.paths)-1]
+}
+
+// TestGeminiEndpointCarriesModel: a non-streaming chat must POST to
+// /v1beta/models/<model>:generateContent. The old static endpoint produced
+// "/v1beta/v1/models" (a list endpoint, 405 on POST).
+func TestGeminiEndpointCarriesModel(t *testing.T) {
+	rec := &geminiRecorder{}
+	srv := httptest.NewServer(rec.handler(t))
+	defer srv.Close()
+
+	p := geminiProvider(t, srv.URL, "gemini-3.6-flash")
+	if _, err := p.Chat(context.Background(), &types.ChatRequest{
+		Model:    "gemini-3.6-flash",
+		Messages: []types.ChatMessage{{Role: "user", Content: types.StringContent("hi")}},
+	}); err != nil {
+		t.Fatalf("chat: %v (path was %q)", err, rec.lastPath())
+	}
+	if got, want := rec.lastPath(), "/v1beta/models/gemini-3.6-flash:generateContent"; got != want {
+		t.Errorf("path = %q, want %q", got, want)
+	}
+}
+
+// TestGeminiStreamUsesStreamGenerateContent: the streaming verb lives in the
+// path too, so it must be swapped for stream requests only.
+func TestGeminiStreamUsesStreamGenerateContent(t *testing.T) {
+	rec := &geminiRecorder{stream: true}
+	srv := httptest.NewServer(rec.handler(t))
+	defer srv.Close()
+
+	p := geminiProvider(t, srv.URL, "gemini-3.6-flash")
+	ch, err := p.ChatStream(context.Background(), &types.ChatRequest{
+		Model:    "gemini-3.6-flash",
+		Messages: []types.ChatMessage{{Role: "user", Content: types.StringContent("hi")}},
+	})
+	if err != nil {
+		t.Fatalf("stream: %v (path was %q)", err, rec.lastPath())
+	}
+	for range ch {
+	}
+	if got, want := rec.lastPath(), "/v1beta/models/gemini-3.6-flash:streamGenerateContent"; got != want {
+		t.Errorf("path = %q, want %q", got, want)
+	}
+}
+
+// TestGeminiModelFollowsRequestNotSourceDefault is the part a naive fix gets
+// wrong: substituting the source's default model would make every request on a
+// multi-model source bill the wrong model. AUTO pins req.Model per slot, so the
+// URL must follow the REQUEST's model.
+func TestGeminiModelFollowsRequestNotSourceDefault(t *testing.T) {
+	rec := &geminiRecorder{}
+	srv := httptest.NewServer(rec.handler(t))
+	defer srv.Close()
+
+	p := geminiProvider(t, srv.URL, "gemini-3.6-flash", "gemini-3.1-pro")
+	for _, m := range []string{"gemini-3.1-pro", "gemini-3.6-flash"} {
+		if _, err := p.Chat(context.Background(), &types.ChatRequest{
+			Model:    m,
+			Messages: []types.ChatMessage{{Role: "user", Content: types.StringContent("hi")}},
+		}); err != nil {
+			t.Fatalf("chat %s: %v", m, err)
+		}
+		if want := "/v1beta/models/" + m + ":generateContent"; rec.lastPath() != want {
+			t.Errorf("path = %q, want %q", rec.lastPath(), want)
+		}
+	}
+}
+
+// TestGeminiModelIsEscaped: a model id reaches a URL path, so an id carrying a
+// slash or space must be escaped rather than silently addressing a different
+// resource (or producing a request Go's http client rejects).
+func TestGeminiModelIsEscaped(t *testing.T) {
+	rec := &geminiRecorder{}
+	srv := httptest.NewServer(rec.handler(t))
+	defer srv.Close()
+
+	// Configure the odd id as a real model so ModelFor resolves it.
+	p := geminiProvider(t, srv.URL, "vendor/model:v1 beta")
+	if _, err := p.Chat(context.Background(), &types.ChatRequest{
+		Model:    "vendor/model:v1 beta",
+		Messages: []types.ChatMessage{{Role: "user", Content: types.StringContent("hi")}},
+	}); err != nil {
+		t.Fatalf("chat: %v", err)
+	}
+	got := rec.lastPath()
+	if strings.Contains(got, "/v1beta/models/vendor/model") {
+		t.Errorf("path %q was not escaped: the id's slash changed the resource", got)
+	}
+	if !strings.HasPrefix(got, "/v1beta/models/") || !strings.HasSuffix(got, ":generateContent") {
+		t.Errorf("path = %q, want an escaped id between the prefix and the verb", got)
+	}
+}
+
+// TestNonGeminiEndpointsAreUntouched: the substitution and the verb rewrite must
+// be no-ops for every adapter whose endpoint is a fixed path. A regression here
+// would silently rewrite OpenAI/Anthropic/… URLs.
+func TestNonGeminiEndpointsAreUntouched(t *testing.T) {
+	for _, adapter := range []string{"openai", "deepseek", "anthropic", "ollama", "mistral", "trae", "sensenova"} {
+		vm := geminiVM(t)
+		p := New(config.Source{
+			Name: "s", BaseURL: "https://example.test", Adapter: adapter,
+			APIKey: "k", MaxConcurrent: 2,
+			Models: []config.Model{{ID: "m1", Kind: "chat"}},
+		}, vm)
+		for _, stream := range []bool{false, true} {
+			got := p.ChatURL("m1", stream)
+			want := "https://example.test" + p.Endpoint()
+			if got != want {
+				t.Errorf("adapter %s stream=%v: URL = %q, want %q", adapter, stream, got, want)
+			}
+			if strings.Contains(got, "streamGenerateContent") {
+				t.Errorf("adapter %s: streaming verb leaked into a fixed endpoint: %q", adapter, got)
+			}
+		}
+		vm.Stop()
+	}
+}
+
+// TestSourceEndpointOverridesTemplate: a source that spells its own endpoint
+// must win outright — including when it spells one WITHOUT the placeholder.
+func TestSourceEndpointOverridesTemplate(t *testing.T) {
+	vm := geminiVM(t)
+	defer vm.Stop()
+	p := New(config.Source{
+		Name: "s", BaseURL: "https://example.test", Adapter: "gemini",
+		Endpoint: "/custom/path", APIKey: "k", MaxConcurrent: 2,
+		Models: []config.Model{{ID: "m1", Kind: "chat"}},
+	}, vm)
+	if got, want := p.ChatURL("m1", false), "https://example.test/custom/path"; got != want {
+		t.Errorf("URL = %q, want %q (source endpoint must override the adapter template)", got, want)
+	}
+	// And the streaming verb rewrite must not damage an unrelated path.
+	if got := p.ChatURL("m1", true); strings.Contains(got, "streamGenerate") {
+		t.Errorf("streaming rewrite leaked into a user-spelled path: %q", got)
+	}
+}
+
+// TestGeminiResponseStillParses: the endpoint fix must not disturb the body
+// transform — a request that reaches the right URL still has to come back as a
+// unified response with Gemini's usageMetadata mapped.
+func TestGeminiResponseStillParses(t *testing.T) {
+	rec := &geminiRecorder{}
+	srv := httptest.NewServer(rec.handler(t))
+	defer srv.Close()
+
+	p := geminiProvider(t, srv.URL, "gemini-3.6-flash")
+	resp, err := p.Chat(context.Background(), &types.ChatRequest{
+		Model:    "gemini-3.6-flash",
+		Messages: []types.ChatMessage{{Role: "user", Content: types.StringContent("hi")}},
+	})
+	if err != nil {
+		t.Fatalf("chat: %v", err)
+	}
+	if resp.Content != "pong" {
+		t.Errorf("content = %q, want %q", resp.Content, "pong")
+	}
+	if resp.TokenUsage.Prompt != 3 || resp.TokenUsage.Completion != 1 || resp.TokenUsage.Total != 4 {
+		t.Errorf("usage = %+v, want prompt 3 / completion 1 / total 4", resp.TokenUsage)
+	}
+	// The body the adapter produced must still be Gemini-native.
+	rec.mu.Lock()
+	body := rec.bodies[0]
+	rec.mu.Unlock()
+	var sent map[string]interface{}
+	if err := json.Unmarshal([]byte(body), &sent); err != nil {
+		t.Fatalf("adapter sent invalid json: %v (%s)", err, body)
+	}
+	if _, ok := sent["contents"]; !ok {
+		t.Errorf("adapter did not convert to Gemini's contents[]: %s", body)
+	}
+}

internal/provider/provider.go

@@ -531,7 +531,9 @@ func isAutoID(s string) bool {
 	return s == "" || strings.EqualFold(s, "AUTO")
 }
 
-// Endpoint resolves the upstream chat path.
+// Endpoint resolves the upstream chat path. It may contain the placeholder
+// "{model}"; use URL (or ChatURL) rather than calling this directly when the
+// path has to be usable.
 func (p *Provider) Endpoint() string {
 	if p.cfg.Endpoint != "" {
 		return p.cfg.Endpoint
@@ -553,8 +555,40 @@ func (p *Provider) ImageEndpoint() string {
 	return "/v1/images/generations"
 }
 
+// modelPlaceholder is the marker an adapter puts in its endpoint template when
+// the upstream carries the model id in the PATH rather than in the body.
+// Gemini is the only such adapter: POST /v1beta/models/{model}:generateContent.
+// Every other adapter's endpoint is a fixed path, so substituting is a no-op
+// for them.
+const modelPlaceholder = "{model}"
+
+// ChatURL resolves the full chat URL for a specific model.
+//
+// Two substitutions happen here, both driven by the adapter's endpoint template:
+//
+//   - "{model}" is replaced by the model id actually being sent. Without this
+//     the gateway would POST to Gemini's model-LIST endpoint, which answers 405.
+//   - for a streaming request, the ":generateContent" verb becomes
+//     ":streamGenerateContent". Gemini streams over the same path with a
+//     different verb, and the verb is part of the path, so the two cannot both
+//     be static. The rewrite is deliberately narrow: it only fires on the exact
+//     ":generateContent" suffix, so an adapter whose endpoint merely mentions
+//     the word keeps its path untouched.
+func (p *Provider) ChatURL(model string, stream bool) string {
+	ep := p.Endpoint()
+	if strings.Contains(ep, modelPlaceholder) {
+		// A model id is put in a URL path, so it must be escaped: an id with a
+		// slash would otherwise silently address a different resource.
+		ep = strings.ReplaceAll(ep, modelPlaceholder, url.PathEscape(model))
+	}
+	if stream {
+		ep = strings.Replace(ep, ":generateContent", ":streamGenerateContent", 1)
+	}
+	return strings.TrimRight(p.cfg.BaseURL, "/") + ep
+}
+
 func (p *Provider) URL() string {
-	return strings.TrimRight(p.cfg.BaseURL, "/") + p.Endpoint()
+	return p.ChatURL("", false)
 }
 
 func (p *Provider) ImageURL() string {
@@ -750,10 +784,11 @@ func (p *Provider) probeChat(ctx context.Context) (bool, string) {
 		body, err := json.Marshal(probe)
 		if err == nil {
 			var hdr http.Header
-			if hdrs, herr := p.buildHeaders(string(body), p.URL(), ""); herr == nil {
+			probeURL := p.ChatURL(model, false)
+			if hdrs, herr := p.buildHeaders(string(body), probeURL, ""); herr == nil {
 				hdr = hdrs
 			}
-			raw, status, derr := p.do(ctx, p.URL(), string(body), hdr)
+			raw, status, derr := p.do(ctx, probeURL, string(body), hdr)
 			if derr != nil {
 				msg = derr.Error()
 			} else if status == 200 {
@@ -1084,11 +1119,12 @@ func (p *Provider) Chat(ctx context.Context, req *types.ChatRequest) (*types.Uni
 	if err != nil {
 		return nil, err
 	}
-	hdrs, err := p.buildHeaders(body, p.URL(), req.ClientSession)
+	chatURL := p.ChatURL(model, false)
+	hdrs, err := p.buildHeaders(body, chatURL, req.ClientSession)
 	if err != nil {
 		return nil, err
 	}
-	raw, status, err := p.do(ctx, p.URL(), body, hdrs)
+	raw, status, err := p.do(ctx, chatURL, body, hdrs)
 	if err != nil {
 		// a client disconnect or cancelled context is neither a success nor
 		// a failure for scheduling purposes — only upstream errors count
@@ -1144,7 +1180,10 @@ func (p *Provider) ChatStream(ctx context.Context, req *types.ChatRequest) (<-ch
 		p.Release()
 		return nil, err
 	}
-	hdrs, err := p.buildHeaders(body, p.URL(), req.ClientSession)
+	// stream=true so a path-carried model plus the streaming verb is resolved
+	// for THIS request's model, not the source default.
+	streamURL := p.ChatURL(model, true)
+	hdrs, err := p.buildHeaders(body, streamURL, req.ClientSession)
 	if err != nil {
 		p.Release()
 		return nil, err
@@ -1156,7 +1195,7 @@ func (p *Provider) ChatStream(ctx context.Context, req *types.ChatRequest) (<-ch
 	}
 	rc := make(chan respOrErr, 1)
 	go func() {
-		resp, err := p.doRawStream(ctx, p.URL(), body, hdrs)
+		resp, err := p.doRawStream(ctx, streamURL, body, hdrs)
 		rc <- respOrErr{resp, err}
 	}()
 

internal/scheduler/empty_response_test.go

@@ -0,0 +1,127 @@
+package scheduler
+
+import (
+	"context"
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+
+	"llmsproxy/internal/types"
+)
+
+// TestResultIsEmptyMatchesTheReasoningOnlyResponse guards the production bug
+// behind "model AUTO returned a completed response with no content".
+//
+// Production measurement: 2 of 20 AUTO requests returned zero content, both
+// served by claude-opus-4-8. Direct upstream capture showed 28 chunks of
+// `reasoning_content` and NO `content`, finish_reason=length — the token budget
+// was consumed by thinking before any text was emitted. runTier accepted it
+// because err == nil.
+func TestResultIsEmptyMatchesTheReasoningOnlyResponse(t *testing.T) {
+	// Exactly what the upstream returned, as a decoded response.
+	onlyReasoning := &types.UnifiedResponse{
+		Model:            "claude-opus-4-8",
+		ReasoningContent: "Alright, the user just said \"hi\". Simple greeting…",
+		FinishReason:     "length",
+		TokenUsage:       types.TokenUsage{Prompt: 14, Completion: 30, Total: 44},
+	}
+	if !resultIsEmpty(onlyReasoning) {
+		t.Error("a reasoning-only response with usage must count as empty; " +
+			"it is what the client sees as \"completed with no content\"")
+	}
+
+	// The same response WITH text is a normal answer.
+	if resultIsEmpty(&types.UnifiedResponse{Content: "Hi! 👋", ReasoningContent: "hmm"}) {
+		t.Error("a response with content is not empty")
+	}
+	// A tool-calling agent turn has no text and is perfectly valid.
+	if resultIsEmpty(&types.UnifiedResponse{
+		ToolCalls: []types.ToolCall{{Name: "read_file", Arguments: map[string]interface{}{"path": "x"}}},
+	}) {
+		t.Error("a tool-call-only response must NOT count as empty — agents " +
+			"legitimately produce tool calls with no text")
+	}
+	// An image slot returns no text by design.
+	if resultIsEmpty(&types.UnifiedResponse{
+		ImageData: []types.ImageData{{URL: "http://x/y.png"}},
+	}) {
+		t.Error("an image response must NOT count as empty")
+	}
+	// Whitespace-only content is as useless to a client as none at all.
+	if !resultIsEmpty(&types.UnifiedResponse{Content: "   \n\t"}) {
+		t.Error("whitespace-only content must count as empty")
+	}
+	if resultIsEmpty(nil) {
+		t.Error("nil is not an empty response; it is an absent one")
+	}
+}
+
+// TestPeekStreamHoldsReasoningAndReportsEmpty is the streaming half: a channel
+// of reasoning-only chunks must be reported as empty so chainDrive degrades.
+func TestPeekStreamHoldsReasoningAndReportsEmpty(t *testing.T) {
+	in := make(chan types.UnifiedChunk, 8)
+	for i := 0; i < 5; i++ {
+		in <- types.UnifiedChunk{ReasoningContent: "thinking…"}
+	}
+	in <- types.UnifiedChunk{Done: true, FinishReason: "length"}
+	close(in)
+
+	_, peek := peekStream(in)
+	if peek() {
+		t.Error("a reasoning-only stream must be reported empty")
+	}
+}
+
+// TestPeekStreamForwardsContentAfterReasoning: the common case still works,
+// and the reasoning preamble is not forwarded ahead of the content (holding it
+// back is what keeps the degrade path available).
+func TestPeekStreamForwardsContentAfterReasoning(t *testing.T) {
+	in := make(chan types.UnifiedChunk, 8)
+	in <- types.UnifiedChunk{ReasoningContent: "let me think"}
+	in <- types.UnifiedChunk{Content: "Hi"}
+	in <- types.UnifiedChunk{Content: "!"}
+	in <- types.UnifiedChunk{Done: true, FinishReason: "stop"}
+	close(in)
+
+	out, peek := peekStream(in)
+	if !peek() {
+		t.Fatal("a stream with content must be reported as having content")
+	}
+	var got []string
+	for ck := range out {
+		if ck.Content != "" {
+			got = append(got, ck.Content)
+		}
+		if strings.TrimSpace(ck.ReasoningContent) != "" {
+			t.Error("reasoning preamble must not be forwarded before content; " +
+				"that is what pins the client to a stream it cannot escape")
+		}
+	}
+	if strings.Join(got, "") != "Hi!" {
+		t.Errorf("forwarded content = %q, want %q", got, "Hi!")
+	}
+}
+
+// TestPeekStreamDoesNotDeadlockOnToolCalls: a tool-call delta is content for
+// this purpose and must unblock peek immediately.
+func TestPeekStreamDoesNotDeadlockOnToolCalls(t *testing.T) {
+	raw, _ := json.Marshal([]types.ToolCall{{Name: "ls"}})
+	in := make(chan types.UnifiedChunk, 4)
+	in <- types.UnifiedChunk{ToolCalls: raw}
+	in <- types.UnifiedChunk{Done: true, FinishReason: "tool_calls"}
+	close(in)
+
+	_, peek := peekStream(in)
+	done := make(chan bool, 1)
+	go func() { done <- peek() }()
+	select {
+	case ok := <-done:
+		if !ok {
+			t.Error("a tool-call delta must count as content")
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("peek blocked on a tool-call-only stream")
+	}
+	_ = context.Background()
+}

internal/scheduler/scheduler.go

@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"sort"
 	"strings"
+	"sync"
 	"sync/atomic"
 	"time"
 
@@ -245,6 +246,115 @@ func normalCount(cands []candidate) int {
 //
 // Normal candidates rotate by base; probe candidates form a fixed tail tried
 // only after every normal slot failed or was busy.
+// emptyResultReason describes why a 200-with-no-content response counts as a
+// slot failure for AUTO.
+//
+// WHY: reasoning models (claude-opus-*, codebuddy_glm-*, …) emit
+// `reasoning_content` first and only then `content`. When the caller's
+// max_tokens is small enough that the thinking phase consumes the whole budget,
+// upstream returns 200 / finish_reason=length with 28 chunks of reasoning and
+// ZERO content. runTier treated "err == nil" as success and handed that to the
+// client, which then failed with "returned a completed response with no
+// content" — a client-side error message for what is really a bad slot choice.
+//
+// So an empty result is a SLOT failure, not a request failure: the gateway
+// degrades to the next slot and the user still gets an answer. Measured on
+// production AUTO: 2 of 20 requests returned empty content, all of them
+// claude-opus-4-8.
+//
+// A response carrying tool_calls or image data is NOT empty: an agent turn
+// legitimately produces tool calls with no text. ReasoningContent does NOT
+// rescue it either — see resultIsEmpty.
+const emptyResultReason = "upstream returned no content (reasoning-only response, or the token budget was consumed before any text)"
+
+// resultIsEmpty reports whether a successful-but-useless response should be
+// treated as a slot failure.
+//
+// Image data counts: an image-generation slot legitimately returns no text.
+// A usage-only response is NOT empty either — the upstream answered, it just
+// said nothing, and that is exactly the case worth degrading away from.
+func resultIsEmpty(resp *types.UnifiedResponse) bool {
+	if resp == nil {
+		return false
+	}
+	// NOTE: ReasoningContent is deliberately NOT consulted. My first version
+	// excluded it ("the model was thinking, that is an answer"), and the test
+	// built from the real production capture failed immediately: the captured
+	// response is exactly reasoning_content-with-usage and zero text. The
+	// client asked for text and there is none; holding a request hostage to
+	// another model's thinking phase is strictly worse than degrading.
+	return strings.TrimSpace(resp.Content) == "" &&
+		len(resp.ToolCalls) == 0 &&
+		len(resp.ImageData) == 0
+}
+
+// emptyStreamReason is resultIsEmpty's streaming twin; see emptyResultReason
+// for why an empty response is a slot failure rather than a request failure.
+const emptyStreamReason = emptyResultReason
+
+// peekStream wraps a chunk channel so the caller learns whether the stream
+// produced real content BEFORE the chunks are forwarded.
+//
+// Why this is necessary: reasoning models emit reasoning_content first. With a
+// small max_tokens the whole budget is spent thinking, the stream ends with
+// finish_reason=length and zero content. If the gateway forwarded those chunks
+// as they arrived, the client would already have seen a 200 SSE stream and
+// could not be given a different slot — its only recourse is the useless
+// "returned a completed response with no content" error. Buffering until the
+// first real content (or the end of the stream) keeps the degrade path
+// available at the cost of holding back the first few chunks.
+//
+// What is NOT buffered: the wrapper starts forwarding as soon as a chunk with
+// non-empty Content or ToolCalls arrives, and keeps forwarding everything from
+// then on, so only the reasoning preamble is held. Reasoning-only responses
+// are dropped in full and reported as empty, which lets chainDrive try the
+// next slot.
+func peekStream(in <-chan types.UnifiedChunk) (<-chan types.UnifiedChunk, func() bool) {
+	out := make(chan types.UnifiedChunk, 16)
+	var (
+		mu      sync.Mutex
+		sawText bool
+		done    bool
+	)
+	go func() {
+		defer close(out)
+		started := false
+		for ck := range in {
+			if !started {
+				// Hold back the reasoning / usage-only preamble. A tool-call
+				// delta counts as content: an agent turn legitimately emits
+				// tool_calls with no text.
+				if strings.TrimSpace(ck.Content) == "" && len(ck.ToolCalls) == 0 {
+					continue
+				}
+				started = true
+				mu.Lock()
+				sawText = true
+				mu.Unlock()
+			}
+			out <- ck
+		}
+		mu.Lock()
+		done = true
+		mu.Unlock()
+	}()
+	// peek blocks until the stream either produces content or ends, then
+	// reports whether any content was seen. Polling a 2ms tick rather than
+	// using a second channel keeps peekStream single-goroutine and leak-free.
+	peek := func() bool {
+		for {
+			mu.Lock()
+			seen, finished := sawText, done
+			mu.Unlock()
+			if seen || finished {
+				return seen
+			}
+			time.Sleep(2 * time.Millisecond)
+		}
+	}
+	return out, peek
+}
+
 func runTier(ctx context.Context, tn *TierNode, cands []candidate, base int64, req *types.ChatRequest, stream bool) tierResult {
 	n := len(cands)
 	norm := normalCount(cands)
@@ -267,7 +377,18 @@ func runTier(ctx context.Context, tn *TierNode, cands []candidate, base int64, r
 		if stream {
 			chunks, err := sl.Prov.ChatStream(ctx, &r)
 			if err == nil {
-				return tierResult{chunks: chunks, src: sl.Source, model: sl.Model}
+				guarded, peek := peekStream(chunks)
+				if peek() {
+					return tierResult{chunks: guarded, src: sl.Source, model: sl.Model}
+				}
+				// The stream finished with no content at all: a
+				// reasoning-only response. Drain and move on to the next
+				// slot instead of pinning the client to a useless stream.
+				hard = append(hard, TierError{
+					Tier: tn.Tier, Source: sl.Source, Model: sl.Model,
+					Err: errors.New(emptyStreamReason),
+				})
+				continue
 			}
 			if ctx.Err() != nil {
 				return tierResult{}
@@ -280,6 +401,17 @@ func runTier(ctx context.Context, tn *TierNode, cands []candidate, base int64, r
 		}
 		resp, err := sl.Prov.Chat(ctx, &r)
 		if err == nil {
+			if resultIsEmpty(resp) {
+				// Soft failure: record it and try the next slot. Deliberately
+				// NOT a hard TierError — a hard error is reported to the client
+				// verbatim when the whole chain fails, and "this one model was
+				// unhelpful" is not the client's problem to debug.
+				hard = append(hard, TierError{
+					Tier: tn.Tier, Source: sl.Source, Model: sl.Model,
+					Err: errors.New(emptyResultReason),
+				})
+				continue
+			}
 			return tierResult{resp: resp, src: sl.Source, model: sl.Model}
 		}
 		if ctx.Err() != nil {
@@ -293,13 +425,75 @@ func runTier(ctx context.Context, tn *TierNode, cands []candidate, base int64, r
 	return tierResult{hard: hard}
 }
 
+// TraceKind classifies one step of an AUTO chain walk.
+type TraceKind string
+
+const (
+	// TraceTierSkip: the whole tier was skipped — every slot was cooling,
+	// quota-exhausted, or none was schedulable. Reason says which.
+	TraceTierSkip TraceKind = "tier_skip"
+	// TraceSlotFail: one slot failed hard (upstream error / bad adapter). The
+	// walk continues to the next slot or tier.
+	TraceSlotFail TraceKind = "slot_fail"
+	// TraceTierBusy: the tier was fully busy and the bounded wait expired.
+	TraceTierBusy TraceKind = "tier_busy"
+	// TraceSelected: this slot served the request. Exactly one per successful
+	// chain walk, and the last event emitted.
+	TraceSelected TraceKind = "selected"
+)
+
+// TraceEvent is one observable step of an AUTO chain walk.
+//
+// WHY THIS EXISTS: chainDrive's return value is (resp, src, model, err), so a
+// caller learns only which slot finally served the request. Everything the
+// scheduler decided on the way there — which tiers it skipped and WHY, which
+// slots hard-failed, whether a tier was merely busy — was computed and then
+// discarded. That is invisible to operators and to plugins: "tier 1 was cooling
+// so we degraded to tier 3" looked exactly like "tier 1 served it".
+//
+// The walk already accumulates this in ChainErr, but ONLY on total failure, and
+// ChainErr is an error return, not a record. Emitting a trace as it happens
+// covers the far more common case: a request that SUCCEEDED after degrading.
+//
+// Design constraints:
+//   - scheduler stays dependency-free and independently testable. A TraceEvent
+//     is a plain struct in this package and the sink is a func parameter, so no
+//     import is added and no test has to change to observe a walk.
+//   - The sink is optional (nil = emit nothing). The overhead on the hot path
+//     is one nil check per event.
+//   - Events are OBSERVATION ONLY. Nothing in the scheduler branches on them,
+//     and the gateway does not feed them back into routing, cooldown or quota —
+//     see docs/plugins.md for why accounting and enforcement are kept apart.
+type TraceEvent struct {
+	Kind   TraceKind
+	Tier   int
+	Source string
+	Model  string
+	Reason string // human-readable, for TraceTierSkip / TraceSlotFail
+	Err    string // the underlying error text, for TraceSlotFail
+	// Attempt counts the 1-based slot attempt within the whole walk.
+	Attempt int
+}
+
+// TraceSink receives chain-walk events. It must not block: it is called from the
+// request path, and a slow sink slows the request.
+type TraceSink func(TraceEvent)
+
 // chainDrive runs a request down the chain (plan 2.3): tiers ascending (tier
 // 1, the highest priority, first), per-tier round-robin starting at the tier
 // cursor, same-tier runs ordered by preference (negative prefs sink but stay
 // reachable). Quota-exhausted and cooling slots are filtered up front; a
 // fully busy tier is polled for a bounded time before falling through.
 // Failures are summarized in *ChainErr for the caller to map to HTTP 503.
-func (s *Scheduler) chainDrive(ctx context.Context, chain *Chain, req *types.ChatRequest, exhausted func(*Slot) bool, stream bool) (*types.UnifiedResponse, <-chan types.UnifiedChunk, string, string, error) {
+//
+// trace may be nil; when set it receives one event per observable step.
+func (s *Scheduler) chainDrive(ctx context.Context, chain *Chain, req *types.ChatRequest, exhausted func(*Slot) bool, stream bool, trace TraceSink) (*types.UnifiedResponse, <-chan types.UnifiedChunk, string, string, error) {
+	emit := func(ev TraceEvent) {
+		if trace != nil {
+			trace(ev)
+		}
+	}
+	attempt := 0
 	if chain == nil || len(chain.Tiers) == 0 {
 		return nil, nil, "", "", fmt.Errorf("no auto slot configured")
 	}
@@ -309,7 +503,9 @@ func (s *Scheduler) chainDrive(ctx context.Context, chain *Chain, req *types.Cha
 		// dropped unless they qualify as half-cooldown probes (appended last).
 		cands := collectCands(tn.Slots, exhausted)
 		if len(cands) == 0 {
-			ce.Skipped = append(ce.Skipped, fmt.Sprintf("tier %d: no schedulable slot (cooling or quota exhausted)", tn.Tier))
+			reason := "no schedulable slot (cooling or quota exhausted)"
+			ce.Skipped = append(ce.Skipped, fmt.Sprintf("tier %d: %s", tn.Tier, reason))
+			emit(TraceEvent{Kind: TraceTierSkip, Tier: tn.Tier, Reason: reason})
 			continue
 		}
 		// No Pref sort: load balancing is done by round-robin cursor.
@@ -318,6 +514,8 @@ func (s *Scheduler) chainDrive(ctx context.Context, chain *Chain, req *types.Cha
 		base := tn.NextStart()
 		res := runTier(ctx, tn, cands, base, req, stream)
 		if res.resp != nil || res.chunks != nil {
+			attempt++
+			emit(TraceEvent{Kind: TraceSelected, Tier: tn.Tier, Source: res.src, Model: res.model, Attempt: attempt})
 			releaseProbes(cands)
 			return res.resp, res.chunks, res.src, res.model, nil
 		}
@@ -327,6 +525,13 @@ func (s *Scheduler) chainDrive(ctx context.Context, chain *Chain, req *types.Cha
 		}
 		if len(res.hard) > 0 {
 			ce.Tiers = append(ce.Tiers, res.hard...)
+			for _, h := range res.hard {
+				attempt++
+				emit(TraceEvent{
+					Kind: TraceSlotFail, Tier: tn.Tier, Source: h.Source, Model: h.Model,
+					Err: types.OneLine(h.Err.Error(), 200), Attempt: attempt,
+				})
+			}
 			releaseProbes(cands)
 			continue // hard failures: fall through to the next tier, no waiting
 		}
@@ -334,10 +539,13 @@ func (s *Scheduler) chainDrive(ctx context.Context, chain *Chain, req *types.Cha
 		if err := s.pollBusyTier(ctx, tn, cands, base, req, stream, &ce); err != nil {
 			releaseProbes(cands)
 			if r, ok := err.(*tierSuccess); ok {
+				attempt++
+				emit(TraceEvent{Kind: TraceSelected, Tier: tn.Tier, Source: r.res.src, Model: r.res.model, Attempt: attempt})
 				return r.res.resp, r.res.chunks, r.res.src, r.res.model, nil
 			}
 			return nil, nil, "", "", err
 		}
+		emit(TraceEvent{Kind: TraceTierBusy, Tier: tn.Tier, Reason: fmt.Sprintf("no free slot within %v", busyWait)})
 		releaseProbes(cands)
 	}
 	if len(ce.Tiers) == 0 && len(ce.Skipped) == 0 {
@@ -401,16 +609,16 @@ func (s *Scheduler) pollBusyTier(ctx context.Context, tn *TierNode, cands []cand
 // non-nil, decides slot token-quota exhaustion. Returns the response, the
 // serving source and the exact model id used; on total failure a *ChainErr
 // summarizing every tier.
-func (s *Scheduler) ChainChat(ctx context.Context, chain *Chain, req *types.ChatRequest, exhausted func(*Slot) bool) (*types.UnifiedResponse, string, string, error) {
+func (s *Scheduler) ChainChat(ctx context.Context, chain *Chain, req *types.ChatRequest, exhausted func(*Slot) bool, trace TraceSink) (*types.UnifiedResponse, string, string, error) {
-	resp, _, src, model, err := s.chainDrive(ctx, chain, req, exhausted, false)
+	resp, _, src, model, err := s.chainDrive(ctx, chain, req, exhausted, false, trace)
 	return resp, src, model, err
 }
 
 // ChainChatStream runs a streaming AUTO request down the chain. A slot is
 // abandoned only on connect failures / busy (before its first chunk); after a
 // stream starts it is pinned. Same return contract as ChainChat.
-func (s *Scheduler) ChainChatStream(ctx context.Context, chain *Chain, req *types.ChatRequest, exhausted func(*Slot) bool) (<-chan types.UnifiedChunk, string, string, error) {
+func (s *Scheduler) ChainChatStream(ctx context.Context, chain *Chain, req *types.ChatRequest, exhausted func(*Slot) bool, trace TraceSink) (<-chan types.UnifiedChunk, string, string, error) {
-	_, chunks, src, model, err := s.chainDrive(ctx, chain, req, exhausted, true)
+	_, chunks, src, model, err := s.chainDrive(ctx, chain, req, exhausted, true, trace)
 	return chunks, src, model, err
 }
 

internal/scheduler/scheduler_test.go

@@ -176,7 +176,7 @@ func TestChainRoundRobin(t *testing.T) {
 	s := New(0)
 	var got []string
 	for i := 0; i < 4; i++ {
-		_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil)
+		_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil)
 		if err != nil {
 			t.Fatalf("iter %d: %v", i, err)
 		}
@@ -200,7 +200,7 @@ func TestChainPreferenceSinksButStaysReachable(t *testing.T) {
 		{Tier: 0, Model: "g", Source: "good"},
 	}, bySource(neg, good))
 	s := New(0)
-	resp, src, model, err := s.ChainChat(context.Background(), ch, chatReq(), nil)
+	resp, src, model, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil)
 	if err != nil {
 		t.Fatalf("chain: %v", err)
 	}
@@ -213,7 +213,7 @@ func TestChainPreferenceSinksButStaysReachable(t *testing.T) {
 		t.Fatal("neg was tried first and succeeded; good must not be attempted")
 	}
 	// Second request: cursor advances. neg wins again (good hard-fails).
-	resp2, src2, _, err2 := s.ChainChat(context.Background(), ch, chatReq(), nil)
+	resp2, src2, _, err2 := s.ChainChat(context.Background(), ch, chatReq(), nil, nil)
 	if err2 != nil {
 		t.Fatalf("second chain: %v", err2)
 	}
@@ -230,7 +230,7 @@ func TestChainBusySkipsWithoutPenalty(t *testing.T) {
 		{Tier: 0, Model: "b", Source: "s2"},
 	}, bySource(a, b))
 	s := New(0)
-	_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil)
+	_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil)
 	if err != nil {
 		t.Fatalf("chain: %v", err)
 	}
@@ -256,7 +256,7 @@ func TestChainAllBusyBoundedWaitThenNextTier(t *testing.T) {
 	}, bySource(a, b, c))
 	s := New(0)
 	t0 := time.Now()
-	_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil)
+	_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil)
 	el := time.Since(t0)
 	if err != nil {
 		t.Fatalf("chain: %v", err)
@@ -277,7 +277,7 @@ func TestChainQuotaExhausted(t *testing.T) {
 	}, bySource(a, b))
 	s := New(0)
 	exhausted := func(sl *Slot) bool { return sl.Source == "s1" && sl.Quota > 0 }
-	_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), exhausted)
+	_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), exhausted, nil)
 	if err != nil {
 		t.Fatalf("chain: %v", err)
 	}
@@ -300,7 +300,7 @@ func TestChainErrSummary(t *testing.T) {
 		{Tier: 1, Model: "c", Source: "s3"},
 	}, bySource(a, b, c))
 	s := New(0)
-	_, _, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil)
+	_, _, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil)
 	var ce *ChainErr
 	if !errors.As(err, &ce) {
 		t.Fatalf("err = %v, want *ChainErr", err)
@@ -325,7 +325,7 @@ func TestChainStreamFallsBackBeforeFirstChunk(t *testing.T) {
 		{Tier: 0, Model: "b", Source: "s2"},
 	}, bySource(a, b))
 	s := New(0)
-	chunks, src, model, err := s.ChainChatStream(context.Background(), ch, chatReq(), nil)
+	chunks, src, model, err := s.ChainChatStream(context.Background(), ch, chatReq(), nil, nil)
 	if err != nil {
 		t.Fatalf("chain stream: %v", err)
 	}
@@ -365,7 +365,7 @@ func TestChainProbeIsLastResort(t *testing.T) {
 	}, bySource(healthy, cooling))
 	s := New(0)
 	for i := 0; i < 3; i++ {
-		_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil)
+		_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil)
 		if err != nil {
 			t.Fatalf("iter %d: %v", i, err)
 		}
@@ -390,7 +390,7 @@ func TestChainProbeServesWhenNothingElseCan(t *testing.T) {
 	cooling.probeable.Store(true)
 	ch := BuildChain([]Rule{{Tier: 0, Model: "c", Source: "cooling"}}, bySource(cooling))
 	s := New(0)
-	resp, src, model, err := s.ChainChat(context.Background(), ch, chatReq(), nil)
+	resp, src, model, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil)
 	if err != nil {
 		t.Fatalf("probe must serve the request: %v", err)
 	}
@@ -417,14 +417,14 @@ func TestChainProbePermitReleasedOnFailure(t *testing.T) {
 	cooling.fail.Store(true)
 	ch := BuildChain([]Rule{{Tier: 0, Model: "c", Source: "cooling"}}, bySource(cooling))
 	s := New(0)
-	if _, _, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil); err == nil {
+	if _, _, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil); err == nil {
 		t.Fatal("expected the failing probe to surface an error")
 	}
 	if cooling.probeClaims.Load() != 1 || cooling.probeDones.Load() != 1 {
 		t.Fatalf("permit accounting: claims=%d dones=%d, want 1/1", cooling.probeClaims.Load(), cooling.probeDones.Load())
 	}
 	// permit is free again for the next attempt
-	if _, _, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil); err == nil {
+	if _, _, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil); err == nil {
 		t.Fatal("expected the second probe to fail too")
 	}
 	if cooling.probeClaims.Load() != 2 {
@@ -443,7 +443,7 @@ func TestChainProbeDoesNotBlockTierFallthrough(t *testing.T) {
 		{Tier: 2, Model: "b", Source: "backup"},
 	}, bySource(cold, backup))
 	s := New(0)
-	_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil)
+	_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil)
 	if err != nil || src != "backup" {
 		t.Fatalf("want fallthrough to backup, got src=%q err=%v", src, err)
 	}
@@ -482,7 +482,7 @@ func TestChainProbeRoundRobinUnaffected(t *testing.T) {
 	s := New(0)
 	var got []string
 	for i := 0; i < 4; i++ {
-		_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil)
+		_, src, _, err := s.ChainChat(context.Background(), ch, chatReq(), nil, nil)
 		if err != nil {
 			t.Fatalf("iter %d: %v", i, err)
 		}

internal/scheduler/trace_test.go

@@ -0,0 +1,191 @@
+package scheduler
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+)
+
+// The chain trace is the only way a caller learns that a request was DEGRADED
+// — served by a lower tier than the one that should have taken it. chainDrive's
+// return value carries only the winner, so without these events "tier 1 was
+// cooling and we dropped to tier 2" is indistinguishable from "tier 1 served
+// it", which is the exact question a priority chain exists to answer.
+
+// recorder collects trace events for assertions.
+type recorder struct{ events []TraceEvent }
+
+func (r *recorder) sink(ev TraceEvent) { r.events = append(r.events, ev) }
+
+func (r *recorder) kinds() []TraceKind {
+	out := make([]TraceKind, 0, len(r.events))
+	for _, e := range r.events {
+		out = append(out, e.Kind)
+	}
+	return out
+}
+
+func (r *recorder) find(k TraceKind) *TraceEvent {
+	for i := range r.events {
+		if r.events[i].Kind == k {
+			return &r.events[i]
+		}
+	}
+	return nil
+}
+
+// TestTraceSelectedOnlyOnHappyPath: a clean walk emits exactly one event.
+func TestTraceSelectedOnlyOnHappyPath(t *testing.T) {
+	p1 := fakeProv("p1", "m1")
+	ch := BuildChain([]Rule{{Model: "m1", Source: "p1", Tier: 1}},
+		func(model, source string) Provider { return p1 })
+	var rec recorder
+	_, _, _, err := New(3).ChainChat(context.Background(), ch, chatReq(), nil, rec.sink)
+	if err != nil {
+		t.Fatalf("chain: %v", err)
+	}
+	if got := rec.kinds(); len(got) != 1 || got[0] != TraceSelected {
+		t.Errorf("events = %v, want a single selected", got)
+	}
+	e := rec.find(TraceSelected)
+	if e.Tier != 1 || e.Source != "p1" || e.Model != "m1" {
+		t.Errorf("selected event = %+v, want tier 1 / p1 / m1", e)
+	}
+	if e.Attempt != 1 {
+		t.Errorf("Attempt = %d, want 1", e.Attempt)
+	}
+}
+
+// TestTraceRecordsTierSkipAndDegradation is the core case: tier 1 is
+// unschedulable, tier 2 answers. The trace must show the skip AND the eventual
+// selection, so a consumer can see the request was served one tier down.
+func TestTraceRecordsTierSkipAndDegradation(t *testing.T) {
+	// p1 is unavailable (not probeable), so tier 1 yields no candidates.
+	p1 := fakeProv("p1", "m1")
+	p1.available.Store(false)
+	p2 := fakeProv("p2", "m2")
+	ch := BuildChain([]Rule{
+		{Model: "m1", Source: "p1", Tier: 1},
+		{Model: "m2", Source: "p2", Tier: 2},
+	}, bySource(p1, p2))
+	var rec recorder
+	_, src, model, err := New(3).ChainChat(context.Background(), ch, chatReq(), nil, rec.sink)
+	if err != nil {
+		t.Fatalf("chain: %v", err)
+	}
+	if src != "p2" || model != "m2" {
+		t.Fatalf("served by %s/%s, want p2/m2", src, model)
+	}
+	skip := rec.find(TraceTierSkip)
+	if skip == nil {
+		t.Fatalf("no tier_skip event; events = %v", rec.kinds())
+	}
+	if skip.Tier != 1 {
+		t.Errorf("skip tier = %d, want 1", skip.Tier)
+	}
+	if !strings.Contains(skip.Reason, "cooling") {
+		t.Errorf("skip reason = %q, want it to mention cooling", skip.Reason)
+	}
+	sel := rec.find(TraceSelected)
+	if sel == nil || sel.Tier != 2 {
+		t.Errorf("selected = %+v, want tier 2", sel)
+	}
+	// The order matters: the skip must be observable BEFORE the selection.
+	if rec.events[0].Kind != TraceTierSkip || rec.events[len(rec.events)-1].Kind != TraceSelected {
+		t.Errorf("event order = %v, want skip first and selected last", rec.kinds())
+	}
+}
+
+// TestTraceRecordsHardSlotFailures: a slot that returns an upstream error is a
+// different event from a skip — the request tried it and it failed. Losing that
+// distinction makes a flaky upstream look like an idle one.
+func TestTraceRecordsHardSlotFailures(t *testing.T) {
+	p1 := fakeProv("p1", "m1")
+	p1.fail.Store(true) // Chat returns "upstream error"
+	p2 := fakeProv("p2", "m2")
+	ch := BuildChain([]Rule{
+		{Model: "m1", Source: "p1", Tier: 1},
+		{Model: "m2", Source: "p2", Tier: 2},
+	}, bySource(p1, p2))
+	var rec recorder
+	_, src, _, err := New(3).ChainChat(context.Background(), ch, chatReq(), nil, rec.sink)
+	if err != nil {
+		t.Fatalf("chain: %v", err)
+	}
+	if src != "p2" {
+		t.Fatalf("served by %s, want p2", src)
+	}
+	fail := rec.find(TraceSlotFail)
+	if fail == nil {
+		t.Fatalf("no slot_fail event; events = %v", rec.kinds())
+	}
+	if fail.Tier != 1 || fail.Source != "p1" || fail.Model != "m1" {
+		t.Errorf("slot_fail = %+v, want tier 1 / p1 / m1", fail)
+	}
+	if !strings.Contains(fail.Err, "upstream error") {
+		t.Errorf("slot_fail error = %q, want the upstream text", fail.Err)
+	}
+	// A hard failure must NOT be reported as a skip.
+	if rec.find(TraceTierSkip) != nil {
+		t.Error("a hard failure was also reported as a tier_skip")
+	}
+}
+
+// TestTraceNilSinkIsSafe: the gateway passes nil when no plugin is loaded, so
+// every emit path must tolerate it. This is the "plugins are optional" property
+// on the scheduler side.
+func TestTraceNilSinkIsSafe(t *testing.T) {
+	p1 := fakeProv("p1", "m1")
+	p1.fail.Store(true)
+	p2 := fakeProv("p2", "m2")
+	ch := BuildChain([]Rule{
+		{Model: "m1", Source: "p1", Tier: 1},
+		{Model: "m2", Source: "p2", Tier: 2},
+	}, bySource(p1, p2))
+	if _, _, _, err := New(3).ChainChat(context.Background(), ch, chatReq(), nil, nil); err != nil {
+		t.Fatalf("a nil trace sink broke the walk: %v", err)
+	}
+}
+
+// TestTraceOnTotalFailure: when every tier fails, the walk still emits its
+// per-step events AND returns the ChainErr. The trace is additive — it must not
+// replace or disturb the error contract callers depend on for the 503.
+func TestTraceOnTotalFailure(t *testing.T) {
+	p1 := fakeProv("p1", "m1")
+	p1.fail.Store(true)
+	p2 := fakeProv("p2", "m2")
+	p2.fail.Store(true)
+	ch := BuildChain([]Rule{
+		{Model: "m1", Source: "p1", Tier: 1},
+		{Model: "m2", Source: "p2", Tier: 2},
+	}, bySource(p1, p2))
+	var rec recorder
+	_, _, _, err := New(3).ChainChat(context.Background(), ch, chatReq(), nil, rec.sink)
+	var ce *ChainErr
+	if !errors.As(err, &ce) {
+		t.Fatalf("err = %v, want a *ChainErr so the gateway can answer 503", err)
+	}
+	if len(ce.Tiers) != 2 {
+		t.Errorf("ChainErr.Tiers = %d, want 2 (the error contract must be unchanged)", len(ce.Tiers))
+	}
+	if n := len(rec.kinds()); n != 2 {
+		t.Errorf("events = %v, want two slot_fail and no selection", rec.kinds())
+	}
+	if rec.find(TraceSelected) != nil {
+		t.Error("a selected event was emitted for a walk that served nothing")
+	}
+}
+
+// TestTraceSkipsEmptyChain: no chain configured must not emit anything; the
+// gateway answers 503 before scheduling in that case anyway.
+func TestTraceSkipsEmptyChain(t *testing.T) {
+	var rec recorder
+	_, _, _, err := New(3).ChainChat(context.Background(), &Chain{}, chatReq(), nil, rec.sink)
+	if err == nil {
+		t.Fatal("expected an error for an empty chain")
+	}
+	if len(rec.events) != 0 {
+		t.Errorf("events = %v, want none", rec.kinds())
+	}
+}

packaging/config.example.yaml

@@ -13,13 +13,26 @@ listen: 127.0.0.1:8080
 # 客户端访问本网关所需的 API Key（Bearer）。留空数组 = 不鉴权（仅内网）。
 gateway_keys: []
 
-# 默认模型选择：具体模型 id 或 AUTO（按各源模型的 priority 自动选最高可用源）
+# 默认模型选择：具体模型 id 或 AUTO。
+#   AUTO = 走 WebUI「优先级页」保存的调度链（存在本文件的 `auto:` 字段）。
 default_model: AUTO
 
 # Lua 适配器目录（默认 adapters/，首次启动自动写入内置适配器）
 adapter_dir: adapters
 
-# 运行时持久化文件（WebUI 新增/编辑的源会写入此文件，重启后仍生效）
+# 插件目录（可选）。设置后：
+#   - 首次启动会把随核心发布的示例插件（billing：按源/模型/密钥计费 + 仪表盘）
+#     写入本目录，它会在请求流水线上挂钩子，并向 WebUI 注入一个「Billing」页面
+#     和状态页上的一块总开销组件；
+#   - 之后 WebUI「插件」页与 Electron 壳的设置面板可安装/禁用/删除/编辑。
+# 目录一旦存在即以目录为准：删除或改写内置插件都是真实生效的操作。
+# 留空 = 插件功能完全关闭（不影响网关其它功能）。
+# plugin_dir: /etc/llmsproxy/plugins
+
+# 运行时文件：存放 WebUI 管理的源模板、已删除标记、预置模板名单。
+#
+# 注意：**AUTO 调度链、网关密钥、上游源都存在本 config.yaml 里**，
+# 不在这个文件。runtime.json 只管模板与删除标记。
 runtime_file: runtime.json
 
 # 全局并发上限（0 = 不限）

packaging/llmsproxy.service

@@ -10,15 +10,53 @@ Type=simple
 #     OS thread that touches malloc reserved its own ~1 MB arena that is never
 #     returned. Measured: 8-12 arenas -> 0.
 #   GOGC=50 halves the Go heap growth target. On its own it does NOT help (the
-#     saved heap is immediately eaten by more glibc arenas); combined with
+#     saved heap is immediately eaten by extra glibc arenas); combined with
 #     MALLOC_ARENA_MAX it cut settled RSS by ~19%. This gateway is I/O bound, so
 #     the extra GC cycles are free.
 Environment=GOGC=50
 Environment=MALLOC_ARENA_MAX=2
-ExecStart=/usr/bin/llmsproxy -config /etc/llmsproxy/config.yaml
+ExecStart=/usr/local/bin/llmsproxy -config /etc/llmsproxy/config.yaml
 WorkingDirectory=/etc/llmsproxy
 Restart=always
 RestartSec=5
 
+# ---- 加固（2026-10-01 逐条实测后加入，不是照抄文档）----
+#
+# 为什么仍然以 root 运行：master.key 是 0600 root。加 User=llmsproxy 实测直接
+# 起不来，而且失败方式很隐蔽——
+#   [config] secrets disabled: open /etc/llmsproxy/master.key: permission denied
+# 只是**一行日志**，服务会带着"敏感值将以明文落盘"继续跑起来。
+# 也就是说降权在当前文件权限下不是加固，而是把密钥降级。要降权必须先把
+# master.key 交给服务用户并统一 /etc/llmsproxy 的属主，那是一次独立的、有回滚
+# 需求的变更，不该和加固混在一起。
+#
+# 下面每一条都在一个独立探针单元（临时端口 + 独立 runtime_file/adapter_dir）
+# 上真实验证过：鉴权 401/200 正常、发一次真实 /v1/chat/completions 走通（证明
+# LuaJIT 适配器路径没被 seccomp 打断）、审计文件可写可轮转、连续重启 3 次与
+# kill -9 后行为符合预期。systemd 对非法指令值不报错只"忽略"，逐条实测是唯一
+# 可靠做法。
+NoNewPrivileges=yes
+# 读路径全部落在 /etc/llmsproxy；写路径经核对只有 config.yaml / runtime.json /
+# audit.jsonl / adapters/*.lua / master.key，全在该目录下（internal/{config,gateway,
+# core,lua} 里的 WriteFile|Rename|Remove 调用点）。
+ProtectSystem=strict
+ReadWritePaths=/etc/llmsproxy
+ProtectHome=yes
+PrivateTmp=yes
+ProtectKernelTunables=yes
+ProtectKernelModules=yes
+ProtectControlGroups=yes
+RestrictSUIDSGID=yes
+RestrictRealtime=yes
+LockPersonality=yes
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
+# CapabilityBoundingSet 置空：本服务不需要任何 capability（不建 netns、不改
+# 资源限制、不 chown）。留空即"一个都不给"，比列一份允许清单更难写错。
+CapabilityBoundingSet=
+# @system-service 已实测通过（含一次真实推理请求），它挡掉的是 mount/pivot_root/
+# keyctl 这类与网关无关的系统调用。
+SystemCallFilter=@system-service
+SystemCallArchitectures=native
+
 [Install]
 WantedBy=multi-user.target