fix(delegate-task): recover sync results on abort race

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

@@ -186,6 +186,121 @@ describe("executeSyncContinuation - toast cleanup error paths", () => {
     expect(removeTaskCalls[0]).toBe("resume_sync_ses_test")
   })
 
+  test("recovers from pollSyncSession error when result already exists", async () => {
+    const mockClient = {
+      session: {
+        messages: async () => ({
+          data: [
+            { info: { id: "msg_001", role: "user", time: { created: 1000 } } },
+            {
+              info: { id: "msg_002", role: "assistant", time: { created: 2000 }, finish: "end_turn" },
+              parts: [{ type: "text", text: "Response" }],
+            },
+          ],
+        }),
+        promptAsync: async () => ({}),
+        status: async () => ({
+          data: { ses_test: { type: "idle" } },
+        }),
+      },
+    }
+
+    const { executeSyncContinuation } = require("./sync-continuation")
+
+    const deps = {
+      pollSyncSession: async () => "Task aborted.\n\nSession ID: ses_test_12345678",
+      fetchSyncResult: async () => ({ ok: true as const, textContent: "Recovered result" }),
+    }
+
+    const mockCtx = {
+      sessionID: "parent-session",
+      callID: "call-123",
+      metadata: () => {},
+    }
+
+    const mockExecutorCtx = {
+      client: mockClient,
+    }
+
+    const args = {
+      task_id: "ses_test_12345678",
+      prompt: "test prompt",
+      description: "test task",
+      category: "test",
+      load_skills: [],
+      run_in_background: false,
+    }
+
+    //#when
+    const result = await executeSyncContinuation(args, mockCtx, mockExecutorCtx, {
+      sessionID: "parent-session",
+      messageID: "parent-message",
+    }, deps)
+
+    //#then
+    expect(result).toContain("Task continued and completed in")
+    expect(result).toContain("Recovered result")
+    expect(removeTaskCalls.length).toBe(1)
+    expect(removeTaskCalls[0]).toBe("resume_sync_ses_test")
+  })
+
+  test("returns poll error when recovery fetch has no result", async () => {
+    const mockClient = {
+      session: {
+        messages: async () => ({
+          data: [
+            { info: { id: "msg_001", role: "user", time: { created: 1000 } } },
+            {
+              info: { id: "msg_002", role: "assistant", time: { created: 2000 }, finish: "end_turn" },
+              parts: [{ type: "text", text: "Response" }],
+            },
+          ],
+        }),
+        promptAsync: async () => ({}),
+        status: async () => ({
+          data: { ses_test: { type: "idle" } },
+        }),
+      },
+    }
+
+    const { executeSyncContinuation } = require("./sync-continuation")
+
+    const deps = {
+      pollSyncSession: async () => "Task aborted.\n\nSession ID: ses_test_12345678",
+      fetchSyncResult: async () => ({ ok: false as const, error: "No assistant response found" }),
+    }
+
+    const mockCtx = {
+      sessionID: "parent-session",
+      callID: "call-123",
+      metadata: () => {},
+    }
+
+    const mockExecutorCtx = {
+      client: mockClient,
+    }
+
+    const args = {
+      task_id: "ses_test_12345678",
+      prompt: "test prompt",
+      description: "test task",
+      category: "test",
+      load_skills: [],
+      run_in_background: false,
+    }
+
+    //#when
+    const result = await executeSyncContinuation(args, mockCtx, mockExecutorCtx, {
+      sessionID: "parent-session",
+      messageID: "parent-message",
+    }, deps)
+
+    //#then
+    expect(result).toBe("Task aborted.\n\nSession ID: ses_test_12345678")
+    expect(removeTaskCalls.length).toBe(1)
+    expect(removeTaskCalls[0]).toBe("resume_sync_ses_test")
+  })
+
   test("removes toast on successful completion", async () => {
     //#given - mock successful completion with messages growing after anchor
     const mockClient = {
@@ -306,7 +421,8 @@ 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 aborted")
+    expect(result).toContain("Task continued and completed in")
+    expect(result).toContain("Result")
   })
 
   test("no crash when toastManager is null", async () => {

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

@@ -162,7 +162,25 @@ export async function executeSyncContinuation(
         anchorMessageCount,
       }, syncPollTimeoutMs)
       if (pollError) {
-        return pollError
+        const recoveredResult = await deps.fetchSyncResult(client, continuationID, anchorMessageCount)
+        if (!recoveredResult.ok) {
+          return pollError
+        }
+
+        const duration = formatDuration(startTime)
+
+        return `Task continued and completed in ${duration}.
+
+---
+
+${recoveredResult.textContent || "(No text output)"}
+
+${buildTaskMetadataBlock({
+          sessionId: continuationID,
+          taskId: continuationID,
+          agent: resumeAgent,
+          category: args.category,
+        })}`
       }
 
       const result = await deps.fetchSyncResult(client, continuationID, anchorMessageCount)

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

@@ -421,6 +421,37 @@ describe("pollSyncSession", () => {
       expect(result).toContain("ses_abort")
       expect(abortCount).toBe(1)
     })
+
+    test("retries final message fetch on abort before returning aborted", async () => {
+      // given: abort signal set and message fetch keeps failing
+      const { pollSyncSession } = require("./sync-session-poller")
+      let abortCount = 0
+      let messageCallCount = 0
+      const mockClient = {
+        session: {
+          abort: async () => {
+            abortCount++
+          },
+          messages: async () => {
+            messageCallCount++
+            throw new Error("temporary fetch failure")
+          },
+          status: async () => ({ data: {} }),
+        },
+      }
+
+      const result = await pollSyncSession(createMockCtx(true), mockClient, {
+        sessionID: "ses_abort_retry",
+        agentToUse: "test-agent",
+        toastManager: { removeTask: () => {} },
+        taskId: "task_123",
+      })
+
+      // then
+      expect(result).toContain("Task aborted")
+      expect(messageCallCount).toBe(3)
+      expect(abortCount).toBe(1)
+    })
   })
 
   describe("timeout handling", () => {

src/tools/delegate-task/sync-session-poller.ts

@@ -105,19 +105,32 @@ export async function pollSyncSession(
     }
 
     if (ctx.abort?.aborted) {
-      try {
+      let finalMessages: SessionMessage[] | null = null
-        const messages = await fetchSessionMessages(client, input.sessionID)
+      const abortFetchAttempts = 3
+      for (let attempt = 1; attempt <= abortFetchAttempts; attempt++) {
+        try {
+          finalMessages = await fetchSessionMessages(client, input.sessionID)
+          break
+        } catch (error) {
+          log("[task] Final messages fetch failed after abort, retrying", {
+            sessionID: input.sessionID,
+            attempt,
+            maxAttempts: abortFetchAttempts,
+            error: String(error),
+          })
+          if (attempt < abortFetchAttempts) {
+            await wait(syncTiming.POLL_INTERVAL_MS)
+          }
+        }
+      }
+
+      if (finalMessages) {
         const hasNewMessages =
-          input.anchorMessageCount === undefined || messages.length > input.anchorMessageCount
+          input.anchorMessageCount === undefined || finalMessages.length > input.anchorMessageCount
-        if (hasNewMessages && isSessionComplete(messages)) {
+        if (hasNewMessages && isSessionComplete(finalMessages)) {
           log("[task] Abort detected after session already completed", { sessionID: input.sessionID })
           return null
         }
-      } catch (error) {
-        log("[task] Final messages fetch failed after abort, continuing with abort", {
-          sessionID: input.sessionID,
-          error: String(error),
-        })
       }
 
       log("[task] Aborted by user", { sessionID: input.sessionID })

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

@@ -173,7 +173,7 @@ describe("executeSyncTask - cleanup on error paths", () => {
     expect(rollback).toHaveBeenCalledTimes(1)
   })
 
-  test("cleans up toast and subagentSessions when pollSyncSession returns error", async () => {
+  test("recovers from pollSyncSession error when result already exists", async () => {
     const mockClient = {
       session: {
         create: async () => ({ data: { id: "ses_test_12345678" } }),
@@ -185,7 +185,7 @@ describe("executeSyncTask - cleanup on error paths", () => {
     const deps = {
       createSyncSession: async () => ({ ok: true, sessionID: "ses_test_12345678" }),
       sendSyncPrompt: async () => null,
-      pollSyncSession: async () => "Poll error",
+      pollSyncSession: async () => "Task aborted.\n\nSession ID: ses_test_12345678",
       fetchSyncResult: async () => ({ ok: true as const, textContent: "Result" }),
     }
 
@@ -215,14 +215,63 @@ describe("executeSyncTask - cleanup on error paths", () => {
       sessionID: "parent-session",
     }, "test-agent", undefined, undefined, undefined, undefined, deps)
 
-    //#then - should return error and cleanup resources
+    //#then - should recover via fetchSyncResult and cleanup resources
-    expect(result).toBe("Poll error")
+    expect(result).toContain("Task completed in")
+    expect(result).toContain("Result")
     expect(removeTaskCalls.length).toBe(1)
     expect(removeTaskCalls[0]).toBe("sync_ses_test")
     expect(deleteCalls.length).toBe(1)
     expect(deleteCalls[0]).toBe("ses_test_12345678")
   })
 
+  test("returns poll error when recovery fetch has no result", async () => {
+    const mockClient = {
+      session: {
+        create: async () => ({ data: { id: "ses_test_12345678" } }),
+      },
+    }
+
+    const { executeSyncTask } = require("./sync-task")
+
+    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" }),
+    }
+
+    const mockCtx = {
+      sessionID: "parent-session",
+      callID: "call-123",
+      metadata: () => {},
+    }
+
+    const mockExecutorCtx = {
+      client: mockClient,
+      directory: "/tmp",
+      onSyncSessionCreated: null,
+    }
+
+    const args = {
+      prompt: "test prompt",
+      description: "test task",
+      category: "test",
+      load_skills: [],
+      run_in_background: false,
+      command: null,
+    }
+
+    //#when
+    const result = await executeSyncTask(args, mockCtx, mockExecutorCtx, {
+      sessionID: "parent-session",
+    }, "test-agent", undefined, undefined, undefined, undefined, deps)
+
+    //#then
+    expect(result).toBe("Poll error")
+    expect(removeTaskCalls.length).toBe(1)
+    expect(deleteCalls.length).toBe(1)
+  })
+
   test("#given fallback chain set #when sendSyncPrompt fails #then retries with next model", async () => {
     //#given
     const mockClient = {

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

@@ -15,6 +15,11 @@ import { resolveMetadataModel } from "./resolve-metadata-model"
 import { shouldRetryError } from "../../shared/model-error-classifier"
 import type { ModelFallbackState } from "../../hooks/model-fallback/hook"
 
+function shouldAttemptPollErrorRecovery(pollError: string): boolean {
+  const normalized = pollError.toLowerCase()
+  return normalized.includes("aborted") || normalized.includes("abort")
+}
+
 export async function executeSyncTask(
   args: DelegateTaskArgs,
   ctx: ToolContextWithMetadata,
@@ -213,6 +218,31 @@ export async function executeSyncTask(
           taskId,
         }, syncPollTimeoutMs)
         if (pollError) {
+          if (shouldAttemptPollErrorRecovery(pollError)) {
+            const recoveredResult = await deps.fetchSyncResult(client, activeSessionID)
+            if (recoveredResult.ok) {
+              const duration = formatDuration(startTime)
+
+              const actualModelStr = effectiveCategoryModel
+                ? `${effectiveCategoryModel.providerID}/${effectiveCategoryModel.modelID}`
+                : undefined
+              const parentModelStr = parentContext.model
+                ? `${parentContext.model.providerID}/${parentContext.model.modelID}`
+                : undefined
+              let modelRoutingNote = ""
+              if (actualModelStr && parentModelStr && actualModelStr !== parentModelStr) {
+                modelRoutingNote = `\n⚠️  Model fallback used: requested ${parentModelStr}, executed ${actualModelStr}`
+              }
+
+              return `Task completed in ${duration}.\n\n---\n\n${recoveredResult.textContent || "(No text output)"}${modelRoutingNote}\n\n${buildTaskMetadataBlock({
+                sessionId: activeSessionID,
+                taskId: activeSessionID,
+                agent: agentToUse,
+                category: args.category,
+              })}`
+            }
+          }
+
           const nextFallbackModel = shouldRetryError({ message: pollError })
             ? getNextSyncFallbackModel(activeSessionID, fallbackState)
             : null