fix(delegate-task): gate continuation recovery to canonical abort errors

src/tools/delegate-task/sync-continuation.test.ts

@@ -186,7 +186,7 @@ describe("executeSyncContinuation - toast cleanup error paths", () => {
     expect(removeTaskCalls[0]).toBe("resume_sync_ses_test")
   })
 
-  test("recovers from pollSyncSession error when result already exists", async () => {
+  test("recovers from MessageAbortedError poll error when result already exists", async () => {
     const mockClient = {
       session: {
         messages: async () => ({
@@ -208,7 +208,7 @@ describe("executeSyncContinuation - toast cleanup error paths", () => {
     const { executeSyncContinuation } = require("./sync-continuation")
 
     const deps = {
-      pollSyncSession: async () => "Task aborted.\n\nSession ID: ses_test_12345678",
+      pollSyncSession: async () => "MessageAbortedError: aborted by user",
       fetchSyncResult: async () => ({ ok: true as const, textContent: "Recovered result" }),
     }
 
@@ -244,7 +244,7 @@ describe("executeSyncContinuation - toast cleanup error paths", () => {
     expect(removeTaskCalls[0]).toBe("resume_sync_ses_test")
   })
 
-  test("returns poll error when recovery fetch has no result", async () => {
+  test("returns MessageAbortedError poll error when recovery fetch has no result", async () => {
     const mockClient = {
       session: {
         messages: async () => ({
@@ -266,7 +266,7 @@ describe("executeSyncContinuation - toast cleanup error paths", () => {
     const { executeSyncContinuation } = require("./sync-continuation")
 
     const deps = {
-      pollSyncSession: async () => "Task aborted.\n\nSession ID: ses_test_12345678",
+      pollSyncSession: async () => "MessageAbortedError: aborted by user",
       fetchSyncResult: async () => ({ ok: false as const, error: "No assistant response found" }),
     }
 
@@ -296,7 +296,7 @@ describe("executeSyncContinuation - toast cleanup error paths", () => {
     }, deps)
 
     //#then
-    expect(result).toBe("Task aborted.\n\nSession ID: ses_test_12345678")
+    expect(result).toBe("MessageAbortedError: aborted by user")
     expect(removeTaskCalls.length).toBe(1)
     expect(removeTaskCalls[0]).toBe("resume_sync_ses_test")
   })
@@ -421,8 +421,7 @@ describe("executeSyncContinuation - toast cleanup error paths", () => {
     //#then - removeTask should be called at least once (poller and finally may both call it)
     expect(removeTaskCalls.length).toBeGreaterThanOrEqual(1)
     expect(removeTaskCalls[0]).toBe("resume_sync_ses_test")
-    expect(result).toContain("Task continued and completed in")
-    expect(result).toContain("Result")
+    expect(result).toBe("Task aborted.\n\nSession ID: ses_test_12345678")
   })
 
   test("no crash when toastManager is null", async () => {

src/tools/delegate-task/sync-continuation.ts

@@ -24,6 +24,28 @@ type ResumeContext = {
   anchorMessageCount?: number
 }
 
+function shouldAttemptPollErrorRecovery(pollError: string): boolean {
+  const trimmed = pollError.trim()
+
+  if (trimmed.length === 0) {
+    return false
+  }
+
+  if (/\bMessageAbortedError\b/u.test(trimmed)) {
+    return true
+  }
+
+  if (/\bDOMException\b/u.test(trimmed) && /\bAbortError\b/u.test(trimmed)) {
+    return true
+  }
+
+  if (/\bAbortError\b/u.test(trimmed) && !/\bTask aborted\b/u.test(trimmed)) {
+    return true
+  }
+
+  return false
+}
+
 async function resolveResumeContext(
   client: ExecutorContext["client"],
   continuationID: string
@@ -161,7 +183,7 @@ export async function executeSyncContinuation(
         taskId,
         anchorMessageCount,
       }, syncPollTimeoutMs)
-      if (pollError) {
+      if (pollError && shouldAttemptPollErrorRecovery(pollError)) {
         const recoveredResult = await deps.fetchSyncResult(client, continuationID, anchorMessageCount)
         if (!recoveredResult.ok) {
           return pollError
@@ -181,6 +203,8 @@ ${buildTaskMetadataBlock({
           agent: resumeAgent,
           category: args.category,
         })}`
+      } else if (pollError) {
+        return pollError
       }
 
       const result = await deps.fetchSyncResult(client, continuationID, anchorMessageCount)

src/tools/delegate-task/sync-task.test.ts

@@ -275,7 +275,7 @@ describe("executeSyncTask - cleanup on error paths", () => {
     expect(fetchSyncResultCalled).toBe(false)
   })
 
-  test("returns poll error when recovery fetch has no result", async () => {
+  test("returns abort poll error when recovery fetch has no result", async () => {
     const mockClient = {
       session: {
         create: async () => ({ data: { id: "ses_test_12345678" } }),
@@ -284,11 +284,16 @@ describe("executeSyncTask - cleanup on error paths", () => {
 
     const { executeSyncTask } = require("./sync-task")
 
+    let fetchSyncResultCalled = false
+
     const deps = {
       createSyncSession: async () => ({ ok: true, sessionID: "ses_test_12345678" }),
       sendSyncPrompt: async () => null,
-      pollSyncSession: async () => "Poll error",
-      fetchSyncResult: async () => ({ ok: false as const, error: "No assistant response found" }),
+      pollSyncSession: async () => "MessageAbortedError: aborted by user",
+      fetchSyncResult: async () => {
+        fetchSyncResultCalled = true
+        return { ok: false as const, error: "No assistant response found" }
+      },
     }
 
     const mockCtx = {
@@ -318,7 +323,8 @@ describe("executeSyncTask - cleanup on error paths", () => {
     }, "test-agent", undefined, undefined, undefined, undefined, deps)
 
     //#then
-    expect(result).toBe("Poll error")
+    expect(result).toBe("MessageAbortedError: aborted by user")
+    expect(fetchSyncResultCalled).toBe(true)
     expect(removeTaskCalls.length).toBe(1)
     expect(deleteCalls.length).toBe(1)
   })