feat(channels): credits_pool_reason —— 区分「真的用尽」与「查不到」

## 为什么需要（参考同款修复，用户报障 2026-09-29）
把两者混成一句"额度都已用尽"会让**一次网络抖动伪装成钱花完了** —— 用户于是
去解锁永久积分、或白等到明天，而号里其实有钱。两者的**正确动作完全相反**：
  exhausted → 等额度重置
  unknown   → 稍后重试 / 查网络与凭据（**不要**动永久积分锁定）
  locked    → 可解锁永久积分（同样不是"用尽"）

我们此前**没有**这个出口：`credits_balances` 只报逐账号错误，调用方拿不到
"为什么整池不可用"的结论，只能自己猜。

## 实现
新增 `channels/credits/pool_reason`，返回 `reason` ∈
`no_accounts | unknown | usable | locked | exhausted` + 可读 detail。
判定优先级（顺序即语义）：
  no_accounts（无启用账号）
  → unknown（平台未声明余额端点 —— **无法判定 ≠ 用尽**）
  → usable（有可用账号）
  → unknown（**有查询失败** —— 不能当成用尽）
  → locked（锁定且只剩永久积分）
  → exhausted（都查到了且确为 0）

## 判据（6 条 + 变异 2/2）
internal/core/channels_pool_reason_test.go
- 余额确为 0 → exhausted
- 查询失败 → unknown（且说明必须点明"查询失败"）
- 无启用账号 → no_accounts
- 有钱 → usable
- 无余额端点 → unknown（不编造用尽）
- 锁定且只剩永久积分 → locked，且**解锁后同一份余额变 usable**
  （证明 locked ≠ exhausted）
变异：查询失败也报 exhausted → 报红；locked 混同 exhausted → 报红。

## 踩到的坑（都是我的判据/夹具问题，非实现）
① 夹具用扁平 `{"total":100}`，而 buddy 的余额是**深层嵌套**
   `data.Response.Data.Accounts[]`（每包含 Status/CycleCapacityRemain/
   DeductionEndTime）—— 夹具形状不对导致全部走 unknown。
② `addAccount` 写死 platform="buddy"，于是"无余额端点"那条用例在 minimax 上
   其实没有账号，命中优先级更高的 no_accounts（**正确**行为）却被判成错。
   加 `addAccountOn(platform, id)` 修正。
③ Lua 里嵌套引号：`"（...不是"额度用尽"）"` 语法错 ⇒ 改用中文引号「」。

internal/core/channels_pool_reason_test.go

@@ -0,0 +1,225 @@
+package core
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"llmsproxy/internal/lua"
+)
+
+// ★ 「为什么没有可用账号」必须区分**真的用尽**与**查不到**。
+//
+// 参考的同款修复（用户报障 2026-09-29）：混成一句"额度都已用尽"会让
+// **一次网络抖动伪装成钱花完了** —— 用户于是去解锁永久积分、或白等到明天，
+// 而号里其实有钱。两者的**正确动作完全相反**：
+//
+//	exhausted → 等额度重置
+//	unknown   → 稍后重试 / 查网络与凭据（**不要**动永久积分锁定）
+//
+// 判据看的是**报出的 reason**（用户据此决定做什么），不是内部计数。
+func TestCreditsPoolReasonDistinguishesExhaustedFromUnknown(t *testing.T) {
+	t.Run("账号都查到了余额但为 0 → exhausted", func(t *testing.T) {
+		h := newPoolReasonHarness(t)
+		h.addAccount("a1")
+		h.serveBalance(0, 0)
+		got := h.reason()
+		if got["reason"] != "exhausted" {
+			t.Fatalf("余额确为 0 时应报 exhausted（用户该等重置），实得 %v：%v",
+				got["reason"], got["detail"])
+		}
+	})
+
+	t.Run("余额查询失败 → unknown（不能伪装成用尽）", func(t *testing.T) {
+		h := newPoolReasonHarness(t)
+		h.addAccount("a1")
+		h.serveBalanceError(500)
+		got := h.reason()
+		if got["reason"] != "unknown" {
+			t.Fatalf("查询失败必须报 unknown —— 报 exhausted 会让网络抖动伪装成钱花完了"+
+				"（用户会去解锁永久积分或白等），实得 %v：%v", got["reason"], got["detail"])
+		}
+		if d, _ := got["detail"].(string); !strings.Contains(d, "查询失败") {
+			t.Fatalf("说明必须点明是查询失败，实得 %q", d)
+		}
+	})
+
+	t.Run("没有启用的账号 → no_accounts", func(t *testing.T) {
+		h := newPoolReasonHarness(t)
+		got := h.reason()
+		if got["reason"] != "no_accounts" {
+			t.Fatalf("无账号时应报 no_accounts，实得 %v", got["reason"])
+		}
+	})
+
+	t.Run("有可用账号 → usable", func(t *testing.T) {
+		h := newPoolReasonHarness(t)
+		h.addAccount("a1")
+		h.serveBalance(100, 0)
+		got := h.reason()
+		if got["reason"] != "usable" {
+			t.Fatalf("有钱时应报 usable，实得 %v", got["reason"])
+		}
+		if u, _ := got["usable"].(float64); int(u) != 1 {
+			t.Fatalf("usable 应为 1，实得 %v", got["usable"])
+		}
+	})
+
+	t.Run("平台无余额端点 → unknown（不编造用尽）", func(t *testing.T) {
+		h := newPoolReasonHarness(t)
+		// ⚠ 必须有**启用的账号**：判定的优先级是
+		//   no_accounts → 无余额端点 → usable → unknown/exhausted
+		// 我第一版在这条用例里忘了加账号，于是命中 no_accounts（优先级更高，
+		// 那是**正确**行为），把正确的实现判成了错。
+		h.addAccountOn("minimax", "m1")
+		// minimax 未声明 balance 端点
+		got := h.reasonOn("minimax")
+		if got["reason"] != "unknown" {
+			t.Fatalf("无余额端点时应报 unknown（无法判定 ≠ 用尽），实得 %v：%v",
+				got["reason"], got["detail"])
+		}
+		if d, _ := got["detail"].(string); !strings.Contains(d, "无法判定") {
+			t.Fatalf("说明必须点明无法判定，实得 %q", d)
+		}
+	})
+}
+
+// 锁定永久积分时，只剩永久积分的账号不可用，且必须报 **locked** 而不是 exhausted
+// （用户动作不同：解锁 vs 等重置）。
+func TestCreditsPoolReasonReportsLockedNotExhausted(t *testing.T) {
+	h := newPoolReasonHarness(t)
+	h.addAccount("a1")
+	// total_fn 取包列表：只有永久积分（到期未知）
+	h.serveBalance(0, 50)
+	if _, err := h.ps.Call("channels", "__set_lock_permanent_probe",
+		map[string]interface{}{"lock": true}); err != nil {
+		t.Fatal(err)
+	}
+	got := h.reason()
+	if got["reason"] != "locked" {
+		t.Fatalf("锁定且只剩永久积分时应报 locked（用户可解锁），实得 %v：%v",
+			got["reason"], got["detail"])
+	}
+	// 解锁后同一份余额应为 usable（证明 locked 不是"用尽"）
+	if _, err := h.ps.Call("channels", "__set_lock_permanent_probe",
+		map[string]interface{}{"lock": false}); err != nil {
+		t.Fatal(err)
+	}
+	h.serveBalance(0, 50)
+	if got2 := h.reason(); got2["reason"] != "usable" {
+		t.Fatalf("解锁后同一份余额应可用（证明 locked ≠ exhausted），实得 %v", got2["reason"])
+	}
+}
+
+// ── harness ──
+
+type poolReasonHarness struct {
+	t       *testing.T
+	ps      *lua.Plugins
+	ts      *httptest.Server
+	body    atomic.Value
+	fail    atomic.Bool
+	hasAcct atomic.Bool
+}
+
+func newPoolReasonHarness(t *testing.T) *poolReasonHarness {
+	t.Helper()
+	h := &poolReasonHarness{t: t}
+	// buddy 的真实形态：包列表嵌在 data.Response.Data.Accounts
+	h.body.Store(buddyPkgBody(0, 0))
+	h.ts = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if h.fail.Load() {
+			w.WriteHeader(500)
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprint(w, h.body.Load().(string))
+	}))
+	t.Cleanup(h.ts.Close)
+
+	c := kernelTestCore(t)
+	ps := c.Plugins()
+	src, err := readBundledChannels(t)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := ps.LoadSource("channels", src); err != nil {
+		t.Fatal(err)
+	}
+	h.ps = ps
+	// buddy 的余额端点指到假上游，并让 total_fn 走包列表分桶
+	if _, err := ps.Call("channels", "set_endpoints", map[string]interface{}{
+		"platform": "buddy",
+		"balance":  map[string]interface{}{"url": h.ts.URL},
+	}); err != nil {
+		t.Logf("set_endpoints(balance) 未支持: %v", err)
+	}
+	return h
+}
+
+func (h *poolReasonHarness) addAccount(id string) {
+	h.t.Helper()
+	h.addAccountOn("buddy", id)
+}
+
+// addAccountOn：往指定平台加账号（我第一版把它写死成 buddy，导致
+// "平台无余额端点"那条用例其实没有该平台的账号，命中了优先级更高的
+// no_accounts —— 判据写错而非实现错）。
+func (h *poolReasonHarness) addAccountOn(platform, id string) {
+	h.t.Helper()
+	if _, err := h.ps.Call("channels", "account_add", map[string]interface{}{
+		"platform": platform, "account_id": id,
+		"credential": `{"access_token":"AT","uid":"u1"}`,
+	}); err != nil {
+		h.t.Fatalf("account_add(%s): %v", platform, err)
+	}
+	h.hasAcct.Store(true)
+}
+
+// serveBalance 直接给"临时/永久"两个桶的金额（内部拼成 buddy 的真实包列表）。
+func (h *poolReasonHarness) serveBalance(expiring, permanent int) {
+	h.fail.Store(false)
+	h.body.Store(buddyPkgBody(expiring, permanent))
+}
+
+// buddyPkgBody 拼一份 buddy 真实形态的余额响应：
+// 包列表在 data.Response.Data.Accounts，每包有 Status / CycleCapacityRemain /
+// DeductionEndTime（毫秒）。到期时间落在窗口内 → 临时桶；未知（0）→ 永久桶。
+func buddyPkgBody(expiring, permanent int) string {
+	pkgs := []string{}
+	if expiring > 0 {
+		// 3 天到期（< 15 天窗口）
+		endMs := (time.Now().Unix() + 3*86400) * 1000
+		pkgs = append(pkgs, fmt.Sprintf(
+			`{"Status":1,"CycleCapacityRemain":%d,"DeductionEndTime":%d}`, expiring, endMs))
+	}
+	if permanent > 0 {
+		// DeductionEndTime=0（未知）⇒ 永久桶
+		pkgs = append(pkgs, fmt.Sprintf(
+			`{"Status":1,"CycleCapacityRemain":%d,"DeductionEndTime":0}`, permanent))
+	}
+	return `{"data":{"Response":{"Data":{"Accounts":[` + strings.Join(pkgs, ",") + `]}}}}`
+}
+
+func (h *poolReasonHarness) serveBalanceError(code int) {
+	h.fail.Store(true)
+}
+
+func (h *poolReasonHarness) reason() map[string]interface{} {
+	h.t.Helper()
+	return h.reasonOn("buddy")
+}
+
+func (h *poolReasonHarness) reasonOn(platform string) map[string]interface{} {
+	h.t.Helper()
+	res, err := h.ps.Call("channels", "credits_pool_reason",
+		map[string]interface{}{"platform": platform})
+	if err != nil {
+		h.t.Fatalf("credits_pool_reason: %v", err)
+	}
+	return jsonOf(h.t, res)
+}

internal/lua/plugins/channels.lua

@@ -52,7 +52,7 @@ plugin.kernel = { "add_source", "list_sources", "probe_all", "reset_health", "st
 
 -- WebUI 可调用的导出函数（POST /api/plugins/channels/call/{fn}）。
 -- set_endpoints 让运维把渠道端点指向自建代理/镜像；测试用它打假上游。
-plugin.exports = { "set_endpoints", "account_add", "account_list", "account_update", "account_clear_credentialless", "account_delete", "account_test", "account_refresh", "account_reorder", "account_reset", "account_retest", "account_adopt", "model_list", "model_refresh", "model_set_disabled", "model_set_disabled_many", "model_set_all_disabled", "model_clear_dead", "provider_status", "provider_set_enabled", "provider_get_order", "provider_set_order", "credits_claim_all", "credits_status", "credits_balances", "credits_permanent_lock", "backup_export", "backup_import", "backup_status", "auto_checkin", "gateway_get_enabled", "gateway_set_enabled", "usage_token_ledger", "usage_badge", "usage_badge_preference", "onboarding_status", "onboarding_claim", "__trae_derive_probe", "__codearts_sign_probe", "__qoder_machine_probe", "__qoder_refresh_probe", "__codearts_dpop_probe", "__codearts_cred_probe", "__codearts_adapter_sign_probe", "__sync_source_probe", "__trae_solo_probe", "__adapter_install_probe", "__store_dir_probe", "__set_loopback_probe", "reap_loopbacks", "__zcode_diag_probe", "__trae_entry_probe", "__is_model_gone_probe", "__rank_accounts_probe", "__inject_refresh_platform_probe", "__clear_capabilities_probe", "__qoder_claim_outcome_probe", "__is_free_probe", "__claim_covers_probe", "__schedule_probe", "__parse_capability_probe", "__inject_capability_probe", "__ttl_reset_probe", "__ttl_probe", "__ttl_invalidate_probe", "__serial_probe", "__serial_release_probe", "__set_legacy_cred_probe", "__read_cred_probe", "__clear_all_creds_probe", "credits_tier_probe", "__set_lock_permanent_probe", "__set_expiring_window_probe", "__expiring_window_probe", "__record_dead_probe", "__catalog_gate_probe", "__catalog_gate_fail_probe", "credits_capability", "claims_capable" }
+plugin.exports = { "set_endpoints", "account_add", "account_list", "account_update", "account_clear_credentialless", "account_delete", "account_test", "account_refresh", "account_reorder", "account_reset", "account_retest", "account_adopt", "model_list", "model_refresh", "model_set_disabled", "model_set_disabled_many", "model_set_all_disabled", "model_clear_dead", "provider_status", "provider_set_enabled", "provider_get_order", "provider_set_order", "credits_claim_all", "credits_status", "credits_balances", "credits_pool_reason", "credits_permanent_lock", "backup_export", "backup_import", "backup_status", "auto_checkin", "gateway_get_enabled", "gateway_set_enabled", "usage_token_ledger", "usage_badge", "usage_badge_preference", "onboarding_status", "onboarding_claim", "__trae_derive_probe", "__codearts_sign_probe", "__qoder_machine_probe", "__qoder_refresh_probe", "__codearts_dpop_probe", "__codearts_cred_probe", "__codearts_adapter_sign_probe", "__sync_source_probe", "__trae_solo_probe", "__adapter_install_probe", "__store_dir_probe", "__set_loopback_probe", "reap_loopbacks", "__zcode_diag_probe", "__trae_entry_probe", "__is_model_gone_probe", "__rank_accounts_probe", "__inject_refresh_platform_probe", "__clear_capabilities_probe", "__qoder_claim_outcome_probe", "__is_free_probe", "__claim_covers_probe", "__schedule_probe", "__parse_capability_probe", "__inject_capability_probe", "__ttl_reset_probe", "__ttl_probe", "__ttl_invalidate_probe", "__serial_probe", "__serial_release_probe", "__set_legacy_cred_probe", "__read_cred_probe", "__clear_all_creds_probe", "credits_tier_probe", "__set_lock_permanent_probe", "__set_expiring_window_probe", "__expiring_window_probe", "__record_dead_probe", "__catalog_gate_probe", "__catalog_gate_fail_probe", "credits_capability", "claims_capable" }
 
 
 
@@ -6605,6 +6605,8 @@ plugin.http = {
     roles = { "admin" }, description = "自动签到开关读写" },
   { path = "channels/credits/status", method = "POST", handler = "credits_status",
     roles = { "admin" }, description = "逐账号签到状态" },
+  { path = "channels/credits/pool_reason", method = "POST", handler = "credits_pool_reason",
+    roles = { "admin" }, description = "为什么没有可用账号（区分用尽/查不到）" },
   { path = "channels/credits/balances", method = "POST", handler = "credits_balances",
     roles = { "admin" }, description = "逐账号余额" },
   { path = "channels/credits/permanent_lock", method = "POST", handler = "credits_permanent_lock",
@@ -7429,6 +7431,96 @@ function plugin.credits_status(req)
   return { status = 200, json = { ok = true, accounts = out } }
 end
 
+-- credits_pool_reason：为什么这个平台**没有可用账号**。
+--
+-- ## 为什么必须单独有这个出口（参考的同款修复，用户报障 2026-09-29）
+-- 把「真的用尽」与「查不到」混成一句"额度都已用尽"会让**一次网络抖动伪装成
+-- 钱花完了** —— 用户于是去解锁永久积分、或白等到明天，而号里其实有钱。
+-- 两者的**正确动作完全相反**：
+--   * exhausted（所有账号都查到了余额，且可用那类积分确实为 0）→ 等额度重置；
+--   * unknown（至少一个账号查询失败，无法判定它是否真没额度）→ 稍后重试、
+--     或检查网络/凭据，**不要**去动永久积分锁定。
+--
+-- 返回 { reason = "exhausted"|"unknown"|"locked"|"no_accounts",
+--        detail = 可读说明, errors = {...}, counts = {...} }。
+function plugin.credits_pool_reason(req)
+  local args = bodyOf(req)
+  if args.platform == nil then args = req end
+  local plat = platformById(args and args.platform)
+  if not plat then return { status = 400, json = { error = "未知平台" } } end
+
+  local accounts = poolList(plat.id)
+  local enabled = 0
+  for _, a in ipairs(accounts) do
+    if a.enabled ~= false then enabled = enabled + 1 end
+  end
+  if enabled == 0 then
+    return { status = 200, json = {
+      ok = true, reason = "no_accounts",
+      detail = "该平台没有启用的账号" .. (#accounts > 0 and ("（有 " .. #accounts .. " 个被停用）") or ""),
+      counts = { total = #accounts, enabled = 0 } } }
+  end
+
+  -- 平台没有余额端点 ⇒ 无法判定，如实说"查不到"而不是"用尽"
+  if not plat.balance then
+    return { status = 200, json = {
+      ok = true, reason = "unknown",
+      detail = "该平台未声明余额端点，无法判定是否用尽（不要当成额度已用尽）",
+      counts = { total = #accounts, enabled = enabled } } }
+  end
+
+  local lockPermanent = plugin.state.settings and plugin.state.settings.lock_permanent_credits
+  local allowPermanent = not lockPermanent
+  local r = rankAccounts(plat.id)
+  local errors = {}
+  -- 逐账号收集查询失败原因（rankAccounts 只给档位，诊断要原因）
+  for _, a in ipairs(accounts) do
+    if a.enabled ~= false then
+      local raw = accountBalanceRaw(plat.id, a.id)
+      if raw == nil then errors[#errors + 1] = a.id end
+    end
+  end
+
+  if #r.usable > 0 then
+    return { status = 200, json = {
+      ok = true, reason = "usable", usable = #r.usable,
+      detail = "有 " .. #r.usable .. " 个可用账号",
+      counts = { total = #accounts, enabled = enabled,
+                 expiring = r.expiring, permanent = r.permanent, none = r.none },
+      locked = lockPermanent and true or false } }
+  end
+
+  -- ★ 无可用：区分「查不到」与「真的用尽」
+  if #errors > 0 then
+    return { status = 200, json = {
+      ok = true, reason = "unknown",
+      detail = "有 " .. #errors .. " 个账号的余额**查询失败**，无法判定它们是否真的没额度"
+        .. "（不要当成额度已用尽：可能是网络抖动；也不要去解锁永久积分）",
+      error_accounts = errors,
+      counts = { total = #accounts, enabled = enabled,
+                 expiring = r.expiring, permanent = r.permanent, none = r.none },
+      locked = lockPermanent and true or false } }
+  end
+
+  if lockPermanent then
+    -- 锁定时只剩永久积分的账号视为不可用（照参考 tier=none 语义）
+    return { status = 200, json = {
+      ok = true, reason = "locked",
+      detail = "永久积分已锁定，" .. tostring(r.permanent) .. " 个只剩永久积分的账号不可用"
+        .. "（如需使用可解锁；这不是「额度用尽」）",
+      counts = { total = #accounts, enabled = enabled,
+                 expiring = r.expiring, permanent = r.permanent, none = r.none },
+      locked = true } }
+  end
+
+  return { status = 200, json = {
+    ok = true, reason = "exhausted",
+    detail = "所有账号都查到了余额，且可用积分确实为 0（等额度重置）",
+    counts = { total = #accounts, enabled = enabled,
+               expiring = r.expiring, permanent = r.permanent, none = r.none },
+    locked = false } }
+end
+
 -- credits_balances：逐账号查余额（对齐参考 credits.balances；
 -- 无 balance 端点的平台返回 {balance=null, error="平台未声明余额端点"}，
 -- 不编造数字 —— 与参考注释「不伪装成余额」同语义）