fix(sync-continuation): improve error handling and toast cleanup

- Add proper error handling in executeSyncContinuation with try-catch blocks
- Ensure toast cleanup happens in all error paths via finally block
- Add anchorMessageCount tracking for accurate result fetching after continuation
- Improve fetchSyncResult to filter messages after anchor point
- Add silent failure detection when no new response is generated

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

@@ -50,11 +50,13 @@ export async function executeSyncContinuation(
   let resumeAgent: string | undefined
   let resumeModel: { providerID: string; modelID: string } | undefined
   let resumeVariant: string | undefined
+  let anchorMessageCount: number | undefined
 
   try {
     try {
       const messagesResp = await client.session.messages({ path: { id: args.session_id! } })
       const messages = (messagesResp.data ?? []) as SessionMessage[]
+      anchorMessageCount = messages.length
       for (let i = messages.length - 1; i >= 0; i--) {
         const info = messages[i].info
         if (info?.agent || info?.model || (info?.modelID && info?.providerID)) {
@@ -91,39 +93,34 @@ export async function executeSyncContinuation(
         parts: [{ type: "text", text: args.prompt }],
       },
     })
-  } catch (promptError) {
-    if (toastManager) {
-      toastManager.removeTask(taskId)
-    }
-    const errorMessage = promptError instanceof Error ? promptError.message : String(promptError)
-    return `Failed to send continuation prompt: ${errorMessage}\n\nSession ID: ${args.session_id}`
-  }
+   } catch (promptError) {
+     if (toastManager) {
+       toastManager.removeTask(taskId)
+     }
+     const errorMessage = promptError instanceof Error ? promptError.message : String(promptError)
+     return `Failed to send continuation prompt: ${errorMessage}\n\nSession ID: ${args.session_id}`
+   }
 
-  const pollError = await pollSyncSession(ctx, client, {
-    sessionID: args.session_id!,
-    agentToUse: resumeAgent ?? "continue",
-    toastManager,
-    taskId,
-  })
-  if (pollError) {
-    return pollError
-  }
+    try {
+      const pollError = await pollSyncSession(ctx, client, {
+        sessionID: args.session_id!,
+        agentToUse: resumeAgent ?? "continue",
+        toastManager,
+        taskId,
+        anchorMessageCount,
+      })
+      if (pollError) {
+        return pollError
+      }
 
-  const result = await fetchSyncResult(client, args.session_id!)
-  if (!result.ok) {
-    if (toastManager) {
-      toastManager.removeTask(taskId)
-    }
-    return result.error
-  }
+      const result = await fetchSyncResult(client, args.session_id!, anchorMessageCount)
+     if (!result.ok) {
+       return result.error
+     }
 
-  if (toastManager) {
-    toastManager.removeTask(taskId)
-  }
+     const duration = formatDuration(startTime)
 
-  const duration = formatDuration(startTime)
-
-  return `Task continued and completed in ${duration}.
+     return `Task continued and completed in ${duration}.
 
 ---
 
@@ -132,4 +129,9 @@ ${result.textContent || "(No text output)"}
 <task_metadata>
 session_id: ${args.session_id}
 </task_metadata>`
+   } finally {
+     if (toastManager) {
+       toastManager.removeTask(taskId)
+     }
+   }
 }

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

@@ -3,7 +3,8 @@ import type { SessionMessage } from "./executor-types"
 
 export async function fetchSyncResult(
   client: OpencodeClient,
-  sessionID: string
+  sessionID: string,
+  anchorMessageCount?: number
 ): Promise<{ ok: true; textContent: string } | { ok: false; error: string }> {
   const messagesResult = await client.session.messages({
     path: { id: sessionID },
@@ -15,11 +16,27 @@ export async function fetchSyncResult(
 
   const messages = ((messagesResult as { data?: unknown }).data ?? messagesResult) as SessionMessage[]
 
-  const assistantMessages = messages
+  const messagesAfterAnchor = anchorMessageCount !== undefined ? messages.slice(anchorMessageCount) : messages
+
+  if (anchorMessageCount !== undefined && messagesAfterAnchor.length === 0) {
+    return {
+      ok: false,
+      error: `Session completed but no new response was generated. The model may have failed silently.\n\nSession ID: ${sessionID}`,
+    }
+  }
+
+  const assistantMessages = messagesAfterAnchor
     .filter((m) => m.info?.role === "assistant")
     .sort((a, b) => (b.info?.time?.created ?? 0) - (a.info?.time?.created ?? 0))
   const lastMessage = assistantMessages[0]
 
+  if (anchorMessageCount !== undefined && !lastMessage) {
+    return {
+      ok: false,
+      error: `Session completed but no new response was generated. The model may have failed silently.\n\nSession ID: ${sessionID}`,
+    }
+  }
+
   if (!lastMessage) {
     return { ok: false, error: `No assistant response found.\n\nSession ID: ${sessionID}` }
   }

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

@@ -30,6 +30,7 @@ export async function pollSyncSession(
     agentToUse: string
     toastManager: { removeTask: (id: string) => void } | null | undefined
     taskId: string | undefined
+    anchorMessageCount?: number
   }
 ): Promise<string | null> {
   const syncTiming = getTimingConfig()
@@ -48,7 +49,13 @@ export async function pollSyncSession(
     await new Promise(resolve => setTimeout(resolve, syncTiming.POLL_INTERVAL_MS))
     pollCount++
 
-    const statusResult = await client.session.status()
+    let statusResult: { data?: Record<string, { type: string }> }
+    try {
+      statusResult = await client.session.status()
+    } catch (error) {
+      log("[task] Poll status fetch failed, retrying", { sessionID: input.sessionID, error: String(error) })
+      continue
+    }
     const allStatuses = (statusResult.data ?? {}) as Record<string, { type: string }>
     const sessionStatus = allStatuses[input.sessionID]
 
@@ -65,8 +72,19 @@ export async function pollSyncSession(
       continue
     }
 
-    const messagesResult = await client.session.messages({ path: { id: input.sessionID } })
-    const msgs = ((messagesResult as { data?: unknown }).data ?? messagesResult) as SessionMessage[]
+    let messagesResult: { data?: unknown } | SessionMessage[]
+    try {
+      messagesResult = await client.session.messages({ path: { id: input.sessionID } })
+    } catch (error) {
+      log("[task] Poll messages fetch failed, retrying", { sessionID: input.sessionID, error: String(error) })
+      continue
+    }
+    const rawData = (messagesResult as { data?: unknown })?.data ?? messagesResult
+    const msgs = Array.isArray(rawData) ? (rawData as SessionMessage[]) : []
+
+    if (input.anchorMessageCount !== undefined && msgs.length <= input.anchorMessageCount) {
+      continue
+    }
 
     if (isSessionComplete(msgs)) {
       log("[task] Poll complete - terminal finish detected", { sessionID: input.sessionID, pollCount })