From 8b1696f5e57471455cf9fcfe7a995e3fff18e012 Mon Sep 17 00:00:00 2001
From: YeonGyu-Kim <code.yeon.gyu@gmail.com>
Date: Mon, 11 May 2026 09:20:14 +0900
Subject: [PATCH] fix(delegate-task): prevent stale-text abort recovery

---
 src/tools/delegate-task/sync-continuation.ts  |  4 +-
 .../delegate-task/sync-result-fetcher.test.ts | 61 +++++++++++++++++++
 .../delegate-task/sync-result-fetcher.ts      | 23 ++++++-
 src/tools/delegate-task/sync-task.ts          |  4 +-
 4 files changed, 89 insertions(+), 3 deletions(-)

diff --git a/src/tools/delegate-task/sync-continuation.ts b/src/tools/delegate-task/sync-continuation.ts
index 817a7e95d..d2dd3b678 100644
--- a/src/tools/delegate-task/sync-continuation.ts
+++ b/src/tools/delegate-task/sync-continuation.ts
@@ -191,7 +191,9 @@ export async function executeSyncContinuation(
         if (anchorMessageCount === undefined) {
           return pollError
         }
-        const recoveredResult = await deps.fetchSyncResult(client, continuationID, anchorMessageCount)
+        const recoveredResult = await deps.fetchSyncResult(client, continuationID, anchorMessageCount, {
+          strictAbortRecovery: true,
+        })
         if (!recoveredResult.ok) {
           return pollError
         }
diff --git a/src/tools/delegate-task/sync-result-fetcher.test.ts b/src/tools/delegate-task/sync-result-fetcher.test.ts
index 82a41f3f6..400c066ad 100644
--- a/src/tools/delegate-task/sync-result-fetcher.test.ts
+++ b/src/tools/delegate-task/sync-result-fetcher.test.ts
@@ -141,4 +141,65 @@ describe("fetchSyncResult", () => {
     expect(result.ok).toBe(false)
     expect(result.error).toContain("No assistant response found")
   })
+
+  test("strict abort recovery: does not fall back to older text when latest assistant is error", async () => {
+    //#given
+    const { fetchSyncResult } = require("./sync-result-fetcher")
+
+    const mockClient = {
+      session: {
+        messages: async () => ({
+          data: [
+            { info: { id: "msg_001", role: "user", time: { created: 1000 } } },
+            {
+              info: { id: "msg_002", role: "assistant", time: { created: 2000 } },
+              parts: [{ type: "text", text: "Older text" }],
+            },
+            {
+              info: {
+                id: "msg_003",
+                role: "assistant",
+                time: { created: 3000 },
+                error: { name: "MessageAbortedError", message: "The operation was aborted." },
+              },
+              parts: [],
+            },
+          ],
+        }),
+      },
+    }
+
+    //#when
+    const result = await fetchSyncResult(mockClient, "ses_test", 1, { strictAbortRecovery: true })
+
+    //#then
+    expect(result.ok).toBe(false)
+    expect(result.error).toContain("Latest assistant message is an error")
+  })
+
+  test("strict abort recovery: requires latest assistant text output", async () => {
+    //#given
+    const { fetchSyncResult } = require("./sync-result-fetcher")
+
+    const mockClient = {
+      session: {
+        messages: async () => ({
+          data: [
+            { info: { id: "msg_001", role: "user", time: { created: 1000 } } },
+            {
+              info: { id: "msg_002", role: "assistant", time: { created: 2000 } },
+              parts: [{ type: "tool", toolCallId: "t1", toolName: "x", state: "output-available", input: {}, output: {} }],
+            },
+          ],
+        }),
+      },
+    }
+
+    //#when
+    const result = await fetchSyncResult(mockClient, "ses_test", 0, { strictAbortRecovery: true })
+
+    //#then
+    expect(result.ok).toBe(false)
+    expect(result.error).toContain("No assistant text output found in latest response")
+  })
 })
diff --git a/src/tools/delegate-task/sync-result-fetcher.ts b/src/tools/delegate-task/sync-result-fetcher.ts
index 9631d3637..f236d6724 100644
--- a/src/tools/delegate-task/sync-result-fetcher.ts
+++ b/src/tools/delegate-task/sync-result-fetcher.ts
@@ -5,7 +5,8 @@ import { normalizeSDKResponse } from "../../shared"
 export async function fetchSyncResult(
   client: OpencodeClient,
   sessionID: string,
-  anchorMessageCount?: number
+  anchorMessageCount?: number,
+  options?: { strictAbortRecovery?: boolean }
 ): Promise<{ ok: true; textContent: string } | { ok: false; error: string }> {
   const messagesResult = await client.session.messages({
     path: { id: sessionID },
@@ -44,6 +45,26 @@ export async function fetchSyncResult(
     return { ok: false, error: `No assistant response found.\n\nSession ID: ${sessionID}` }
   }
 
+  if (options?.strictAbortRecovery) {
+    if (lastMessage.info && "error" in lastMessage.info) {
+      return {
+        ok: false,
+        error: `Latest assistant message is an error; refusing abort recovery.\n\nSession ID: ${sessionID}`,
+      }
+    }
+
+    const lastTextParts = lastMessage.parts?.filter((p) => p.type === "text" || p.type === "reasoning") ?? []
+    const lastContent = lastTextParts.map((p) => p.text ?? "").filter(Boolean).join("\n")
+    if (!lastContent) {
+      return {
+        ok: false,
+        error: `No assistant text output found in latest response.\n\nSession ID: ${sessionID}`,
+      }
+    }
+
+    return { ok: true, textContent: lastContent }
+  }
+
   // Search assistant messages (newest first) for one with text/reasoning content.
   // The last assistant message may only contain tool calls with no text.
   let textContent = ""
diff --git a/src/tools/delegate-task/sync-task.ts b/src/tools/delegate-task/sync-task.ts
index 556ca8225..dcc4b31e8 100644
--- a/src/tools/delegate-task/sync-task.ts
+++ b/src/tools/delegate-task/sync-task.ts
@@ -240,7 +240,9 @@ export async function executeSyncTask(
         }, syncPollTimeoutMs)
         if (pollError) {
           if (shouldAttemptPollErrorRecovery(pollError)) {
-            const recoveredResult = await deps.fetchSyncResult(client, activeSessionID)
+            const recoveredResult = await deps.fetchSyncResult(client, activeSessionID, undefined, {
+              strictAbortRecovery: true,
+            })
             if (recoveredResult.ok) {
               const duration = formatDuration(startTime)