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-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}` }
   }