Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/internal/service/openai_ws_v2/metrics.go

@@ -0,0 +1,29 @@
+package openai_ws_v2
+
+import (
+	"sync/atomic"
+)
+
+// MetricsSnapshot 是 OpenAI WS v2 passthrough 路径的轻量运行时指标快照。
+type MetricsSnapshot struct {
+	SemanticMutationTotal  int64 `json:"semantic_mutation_total"`
+	UsageParseFailureTotal int64 `json:"usage_parse_failure_total"`
+}
+
+var (
+	// passthrough 路径默认不会做语义改写，该计数通常应保持为 0（保留用于未来防御性校验）。
+	passthroughSemanticMutationTotal  atomic.Int64
+	passthroughUsageParseFailureTotal atomic.Int64
+)
+
+func recordUsageParseFailure() {
+	passthroughUsageParseFailureTotal.Add(1)
+}
+
+// SnapshotMetrics 返回当前 passthrough 指标快照。
+func SnapshotMetrics() MetricsSnapshot {
+	return MetricsSnapshot{
+		SemanticMutationTotal:  passthroughSemanticMutationTotal.Load(),
+		UsageParseFailureTotal: passthroughUsageParseFailureTotal.Load(),
+	}
+}