fix(incidents): batch decision token lookup

apps/api/src/services/decision_manager.py

@@ -2953,6 +2953,52 @@ class DecisionManager:
 
         return None
 
+    async def _find_existing_tokens_for_incidents(
+        self,
+        incident_ids: list[str],
+    ) -> dict[str, DecisionToken]:
+        """
+        批次查找現有決策令牌。
+
+        2026-05-06 Codex: GET /api/v1/incidents 是前端輪詢路徑，不可對每個
+        incident 都掃描一次 decision:*。這裡只掃一次 Redis keyspace，避免
+        200+ incidents 時形成 O(N×M) 延遲與前端控制台卡死。
+        """
+        wanted = set(incident_ids)
+        if not wanted:
+            return {}
+
+        import json
+
+        redis_client = get_redis()
+        found: dict[str, DecisionToken] = {}
+        cursor = 0
+        while True:
+            cursor, keys = await redis_client.scan(
+                cursor=cursor,
+                match=f"{DECISION_TOKEN_PREFIX}*",
+                count=500,
+            )
+
+            for key in keys:
+                try:
+                    data = await redis_client.get(key)
+                    if not data:
+                        continue
+                    token_data = json.loads(data)
+                    incident_id = token_data.get("incident_id")
+                    if incident_id in wanted and incident_id not in found:
+                        found[incident_id] = DecisionToken.from_dict(token_data)
+                        if len(found) == len(wanted):
+                            return found
+                except Exception:
+                    continue
+
+            if cursor == 0:
+                break
+
+        return found
+
     async def _persist_decision_to_db(
         self, incident_id: str, proposal_data: dict
     ) -> None: