feat(safety-net): complete wave 1 atomicity (adr-038, adr-039, debounce, graceful degrade, xclaim)

apps/api/src/services/incident_service.py

@@ -430,6 +430,24 @@ class IncidentService:
             Incident | None: 成功返回 Incident，失敗返回 None
         """
         try:
+            # 0. 去抖動 (Debounce) - 防止告警風暴
+            fingerprint = signal_data.get("fingerprint")
+            if fingerprint:
+                try:
+                    redis_client = get_redis()
+                    debounce_key = f"debounce:{fingerprint}"
+                    # SETNX 若成功表示是新的，給予 3 分鐘 TTL (180s)
+                    is_new = await redis_client.set(debounce_key, "1", ex=180, nx=True)
+                    if not is_new:
+                        logger.info(
+                            "incident_debounced",
+                            fingerprint=fingerprint,
+                            reason="Duplicate signal within 3 minutes",
+                        )
+                        return None
+                except Exception as e:
+                    logger.warning("incident_debounce_redis_error", error=str(e))
+
             # 1. 解析 Signal
             signal = Signal(
                 alert_name=signal_data.get("alert_name", "unknown"),