fix(billing): 过期规则 URL 不再让整个 profile 失效（降级应用 + 点名 URL）

生产现网发现（issue #1 排查）：billing.rules 里一条指向
https://opencode.ai/inference/v1 的规则，在该源 base_url 变成
.../inference/openai/v1 之后匹配不到任何源；严格编译因此让**整个** profile
不生效 —— 账单恒 0、unpriced_reqs 涨到 3.7 万，唯一痕迹是一行启动日志。

- 严格编译失败时降级为 lenient：应用能匹配的规则，其余按 profile default；
- 日志用 ERROR 点名**具体哪条 URL** 写错（新增 billing.UnmatchedRuleURLs），
  并说明未匹配流量的记账去向；
- 判据 TestBillingStaleRuleURLStillAppliesOtherRules：一条过期规则 + 一条有效
  规则 ⇒ 有效规则必须仍然生效。

internal/core/billing_apply_test.go

@@ -0,0 +1,60 @@
+package core
+
+import (
+	"path/filepath"
+	"testing"
+
+	"llmsproxy/internal/config"
+)
+
+// 一个过期的规则 URL 不得让**整个**计费 profile 失效。
+//
+// 真实事故（GitCode issue #1 排查中发现，生产现网）：config.yaml 里
+// `billing.rules[0].url` 是 `https://opencode.ai/inference/v1`，而该源的
+// base_url 已是 `.../inference/openai/v1`。严格编译因此返回
+// "rule url ... matches no configured source base_url"，applyBillingDSL 直接
+// return —— 于是**所有**计费规则都不生效：账单恒为 0、unpriced_reqs 涨到 3.7 万，
+// 而唯一的痕迹是一行启动日志。这正是「静默少报」最严重的一种。
+//
+// 修法：严格编译失败时降级为 lenient（用能匹配的规则），并打 ERROR 说明后果。
+// 一个 URL 写错不该把整个价目表一起葬送；但也不能装作成功。
+func TestBillingStaleRuleURLStillAppliesOtherRules(t *testing.T) {
+	cfg := newTestConfig(t)
+	dir := t.TempDir()
+	cfg.PluginDir = filepath.Join(dir, "plugins")
+	cfg.Sources = []config.Source{
+		{Name: "localzen", BaseURL: "https://opencode.ai/inference/openai/v1", Adapter: "openai",
+			Models: []config.Model{{ID: "m"}}},
+	}
+	cfg.BillingDSL = &config.BillingDSL{
+		Active: "p",
+		Profiles: []config.BillingProfile{{
+			ID: "p",
+			Rules: []config.BillingRule{
+				// 过期 URL：没有任何源的 base_url 与它相等
+				{URL: "https://opencode.ai/inference/v1", Mode: "free"},
+				// 有效规则：必须仍然生效
+				{URL: "https://opencode.ai/inference/openai/v1", Mode: "free"},
+			},
+		}},
+	}
+	c := newTestCore(t, cfg)
+	c.applyBillingDSL()
+
+	raw := c.plugins.Prices("billing")
+	if raw == nil {
+		t.Fatal("billing has no price table (profile never applied)")
+	}
+	prices, ok := raw.(map[string]interface{})
+	if !ok {
+		t.Fatalf("price table shape: %#v", raw)
+	}
+	sources, ok := prices["sources"].(map[string]interface{})
+	if !ok {
+		t.Fatalf("prices has no sources: %#v", prices)
+	}
+	if _, ok := sources["localzen"]; !ok {
+		t.Fatalf("一条过期规则 URL 把整个 profile 弄失效了：有效的 free 规则也没有生效，"+
+			"结果是账单恒为 0 且没有告警。prices=%#v", prices)
+	}
+}

internal/core/core.go

@@ -1057,8 +1057,37 @@ func (c *Core) applyBillingDSL() {
 	}
 	prices, err := billing.Compile(profile, c.cfg.Sources)
 	if err != nil {
-		log.Printf("[billing] profile %q not applied: %v", profile.ID, err)
-		return
+		// ONE stale rule URL must not take the whole price table down with it.
+		//
+		// The strict compiler rejects a profile whose rule matches no source,
+		// which is right for catching typos — but the runtime consequence used
+		// to be a bare `return`: every rule stopped applying, the bill came out
+		// at 0 and unpriced_reqs grew forever, with a single startup log line as
+		// the only trace. Found in production while fixing GitCode issue #1
+		// (a rule still pointed at .../inference/v1 after the source moved to
+		// .../inference/openai/v1; 37k requests had been recorded as unpriced).
+		//
+		// So: apply the rules that DO match, and say exactly what was dropped.
+		// The profile still fails loudly — it just no longer fails silently for
+		// everything else.
+		lenient, lerr := billing.CompileOpts(profile, c.cfg.Sources, true)
+		if lerr != nil {
+			log.Printf("[billing] profile %q not applied: %v (lenient retry also failed: %v)",
+				profile.ID, err, lerr)
+			return
+		}
+		def := profile.Default
+		if def == "" {
+			def = "unpriced"
+		}
+		log.Printf("[billing] ERROR profile %q has %d rule URL(s) matching no configured "+
+			"source: %v — applied the remaining %d rule(s); unmatched traffic falls through "+
+			"to default=%q and keeps counting in unpriced_reqs. FIX THE RULE URL: a stale URL "+
+			"used to zero out the entire price table.", profile.ID,
+			len(billing.UnmatchedRuleURLs(profile, c.cfg.Sources)),
+			billing.UnmatchedRuleURLs(profile, c.cfg.Sources),
+			len(profile.Rules)-len(billing.UnmatchedRuleURLs(profile, c.cfg.Sources)), def)
+		prices = lenient
 	}
 	if err := ps.SetState("billing", map[string]interface{}{"prices": prices}); err != nil {
 		log.Printf("[billing] applying profile %q: %v", profile.ID, err)