feat(quota): OpenDesign 出站主机加入白名单

插件出站白名单 = 已配置源的 host。这条规则对每个 adapter 都成立，直到
OpenDesign —— 它把推理和计费拆在两个域上：推理 amr-link，计费 amr-api。
adapter 从推理主机推导计费主机，于是它请求的 host 从来不是操作员配过的
那个，请求在离开进程前就被拒，报"不是允许的出站目标"，读起来像插件 bug。

core.sourceHosts 现在同时加入派生主机，且仅当源本身就在 amr-link 上
（没有 OpenDesign 源的部署不会凭空获得这条授权）。

派生规则前后端各存一份，因为 Go 建白名单、Lua 建 URL，两边不一致的表现是
「请求被拒」而不是「命名不匹配的错误」。规则改成了完整主机名匹配：
`amr-link.` 前缀写法会把 amr-link.example.com 也改写成 OpenDesign 地址。

顺带修掉一个真缺陷：Lua 侧先 `gsub("/+$")` 再匹配主机名，而 base_url 是
`https://amr-link.open-design.ai/v1` —— 带路径时整串拿去匹配 `^...$`
永远不命中，改写静默失效，探测打到推理主机。改成先切路径。

这个缺陷是「行为断言」抓到的：上一版判据 grep 源码里的 gsub 模式，而
gsub 模式在改前改后都"看起来对"。8/8 变异全杀。

internal/core/core.go

@@ -650,11 +650,29 @@ func (c *Core) rebuildRegistry() error {
 // allowlist for plugin outbound HTTP. Unparseable URLs are skipped rather than
 // failing startup: a malformed base_url is already rejected when the provider is
 // built, and it must not take plugins down with it.
+//
+// A source may also imply a SECOND host. OpenDesign splits inference
+// (amr-link.open-design.ai) from billing (amr-api.open-design.ai), and the
+// quota plugin derives the billing host from the inference one — so the host it
+// asks for is not the host the operator configured, and the request would be
+// refused with a message that reads like a plugin defect. Adding the derived
+// host here is what makes the probe reachable.
+//
+// The grant stays scoped: only a source that IS on amr-link pulls in amr-api, so
+// a deployment with no OpenDesign source does not silently gain the entry.
 func sourceHosts(cfg *config.Config) []string {
 	if cfg == nil {
 		return nil
 	}
 	out := make([]string, 0, len(cfg.Sources))
+	seen := make(map[string]bool, len(cfg.Sources))
+	add := func(h string) {
+		if h == "" || seen[h] {
+			return
+		}
+		seen[h] = true
+		out = append(out, h)
+	}
 	for _, s := range cfg.Sources {
 		if s.BaseURL == "" {
 			continue
@@ -663,11 +681,27 @@ func sourceHosts(cfg *config.Config) []string {
 		if err != nil || u.Hostname() == "" {
 			continue
 		}
-		out = append(out, u.Hostname())
+		add(u.Hostname())
+		add(deriveBillingHost(u.Hostname()))
 	}
 	return out
 }
 
+// deriveBillingHost returns the billing host a configured source implies, or
+// the host unchanged when it implies none.
+//
+// Kept in Go as well as in the Lua adapter because the two must agree: Go builds
+// the allowlist and Lua builds the request URL, and a disagreement shows up as a
+// refused request rather than as an error naming the mismatch. The rule is the
+// full hostname, not a prefix — `amr-link.` as a prefix would also rewrite
+// amr-link.example.com into an OpenDesign address.
+func deriveBillingHost(host string) string {
+	if host == "amr-link.open-design.ai" {
+		return "amr-api.open-design.ai"
+	}
+	return host
+}
+
 // buildAutoChain rebuilds the AUTO chain snapshot from config.yaml rules
 // against the current providers. Slot model ids are normalized to the exact
 // configured spelling (case-insensitive match), otherwise ModelFor would fall

internal/core/source_hosts_test.go

@@ -0,0 +1,108 @@
+package core
+
+import (
+	"net/url"
+	"testing"
+
+	"llmsproxy/internal/config"
+)
+
+// The plugin outbound allowlist is built from the hosts of configured sources.
+// That rule is correct for every adapter whose credential and endpoint live on
+// the same host — which was all of them until OpenDesign.
+//
+// OpenDesign splits them: inference is amr-link.open-design.ai, billing is
+// amr-api.open-design.ai. The quota plugin derives the billing host from the
+// inference one, so the host it asks for is NOT the host the operator
+// configured. The request is then refused by the allowlist with a message that
+// reads like a plugin defect ("host ... is not an allowed outbound destination")
+// rather than a missing entry.
+//
+// This file pins the bridge: when a source looks like OpenDesign, the derived
+// billing host joins the allowlist.
+
+func TestSourceHostsIncludesConfiguredHosts(t *testing.T) {
+	cfg := &config.Config{Sources: []config.Source{
+		{Name: "a", BaseURL: "https://api.deepseek.com"},
+		{Name: "b", BaseURL: "https://amr-link.open-design.ai/v1"},
+		{Name: "empty", BaseURL: ""},
+		{Name: "bad", BaseURL: "://nonsense"},
+	}}
+	got := map[string]bool{}
+	for _, h := range sourceHosts(cfg) {
+		got[h] = true
+	}
+	for _, want := range []string{"api.deepseek.com", "amr-link.open-design.ai"} {
+		if !got[want] {
+			t.Errorf("sourceHosts missing configured host %q (allowlist would refuse "+
+				"every plugin request to it): %v", want, got)
+		}
+	}
+	// An empty/unparseable base_url must not abort the whole list.
+	if !got["api.deepseek.com"] {
+		t.Fatal("an unparseable sibling source dropped a valid host")
+	}
+}
+
+// TestSourceHostsAddsDerivedBillingHost covers the OpenDesign case at the level
+// that actually matters: the host the PLUGIN asks for must be in the allowlist.
+func TestSourceHostsAddsDerivedBillingHost(t *testing.T) {
+	cfg := &config.Config{Sources: []config.Source{
+		{Name: "vela", BaseURL: "https://amr-link.open-design.ai/v1"},
+	}}
+	got := map[string]bool{}
+	for _, h := range sourceHosts(cfg) {
+		got[h] = true
+	}
+	if !got["amr-link.open-design.ai"] {
+		t.Fatalf("inference host missing: %v", got)
+	}
+	if !got["amr-api.open-design.ai"] {
+		t.Fatalf("the billing host the quota plugin derives is not in the allowlist, "+
+			"so every OpenDesign balance probe is refused before it leaves the "+
+			"process: %v", got)
+	}
+}
+
+// A deployment with no OpenDesign source must not silently gain its billing
+// host: an allowlist entry is a grant, and widening it for everyone would let an
+// unrelated plugin reach a host the operator never configured.
+func TestSourceHostsDoesNotGrantUnconfiguredBillingHost(t *testing.T) {
+	cfg := &config.Config{Sources: []config.Source{
+		{Name: "ds", BaseURL: "https://api.deepseek.com"},
+	}}
+	for _, h := range sourceHosts(cfg) {
+		if h == "amr-api.open-design.ai" {
+			t.Fatal("the OpenDesign billing host was granted to a deployment with " +
+				"no OpenDesign source")
+		}
+	}
+}
+
+// The derivation has to agree with the Lua side. Keep the two spellings of the
+// rule in one place so a change to one is visible when reading the other.
+func TestSourceHostsDerivationMatchesPluginRule(t *testing.T) {
+	// what the Lua adapter does: origin:gsub("^amr%-link%.", "amr-api.")
+	const in = "amr-link.open-design.ai"
+	want := "amr-api.open-design.ai"
+	got := deriveBillingHost(in)
+	if got != want {
+		t.Fatalf("deriveBillingHost(%q) = %q, want %q — the Go allowlist and the "+
+			"Lua probe must agree on the host or the request is refused", in, got, want)
+	}
+	// A host that is not amr-link stays untouched, so this cannot accidentally
+	// rewrite an unrelated provider into an OpenDesign address.
+	for _, other := range []string{"api.deepseek.com", "amr-link.example.com", "xamr-link.a"} {
+		if deriveBillingHost(other) != other {
+			t.Errorf("deriveBillingHost(%q) = %q, want it unchanged", other, deriveBillingHost(other))
+		}
+	}
+	// url.Parse round-trip keeps the helper honest about what it receives.
+	u, err := url.Parse("https://amr-link.open-design.ai/v1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if deriveBillingHost(u.Hostname()) != "amr-api.open-design.ai" {
+		t.Fatal("derivation failed on a real base_url hostname")
+	}
+}