fix(chat): heal task bubble pending after completed run

web/src/api/taskRuns.ts

@@ -108,6 +108,7 @@ export async function readTaskRunSSEOnce(
 
 /**
  * 订阅任务 SSE：意外 EOF / 不完整 chunked 时按最后 seq 重订阅同一 run，禁止调用方据此 POST 新 run。
+ * 重连前可经 onGap 轮询 run 终态：若已 completed 等则停止订阅（避免 done 丢失后永久 pending）。
  */
 export async function subscribeTaskRunEvents(
   runId: string,
@@ -117,6 +118,8 @@ export async function subscribeTaskRunEvents(
     maxReconnects?: number;
     reconnectDelayMs?: number;
     sleep?: (ms: number) => Promise<void>;
+    /** Return true to stop reconnecting (caller already settled from GET /runs). */
+    onGap?: (ctx: { afterSeq: number; attempt: number }) => Promise<boolean>;
   },
   signal?: AbortSignal,
 ): Promise<void> {
@@ -131,12 +134,20 @@ export async function subscribeTaskRunEvents(
       const { terminal, lastSeq } = await readTaskRunSSEOnce(runId, afterSeq, handlers.onEvent, signal);
       afterSeq = Math.max(afterSeq, lastSeq);
       if (terminal) return;
-      // 意外 EOF：未见到 done/error，按 after_seq 重连
+      // 意外 EOF：未见到 done/error — 先问 onGap，再按 after_seq 重连
+      if (handlers.onGap) {
+        const stop = await handlers.onGap({ afterSeq, attempt });
+        if (stop) return;
+      }
     } catch (err) {
       if (signal?.aborted) return;
       if (err instanceof TaskRunHttpError && isNonRetryableStatus(err.status)) {
         throw err;
       }
+      if (handlers.onGap) {
+        const stop = await handlers.onGap({ afterSeq, attempt }).catch(() => false);
+        if (stop) return;
+      }
       if (attempt >= maxReconnects) throw err;
     }
     if (attempt >= maxReconnects) {