Bug: needsApproval tool approval-responded state never transitions to output-available (think@0.7.3 + agents@0.13.3) #1627

Bug: Tool approval continuation result not reaching frontend (think@0.7.3 + agents@0.13.3)

Environment

• @cloudflare/think@0.7.3
• agents@0.13.3
• @cloudflare/ai-chat@0.7.2

Description

After a user approves a needsApproval tool, the tool executes successfully on the server, but the tool part state never transitions from approval-responded to output-available on the frontend. The UI permanently shows "Executing..." with a spinning indicator.

Related Issues

• addToolOutput / client-tool auto-continuations don't attach to the response stream — delivered only as an end-of-turn replay #1586 — Fixed _scheduleAutoContinuation 50ms coalesce race condition. Our issue persists after upgrading to the versions that include this fix.
• Tool part state regresses during client tool round-trip; continuation starts but emits no output #1404 — Tool part state regression during client tool round-trip.

Steps to Reproduce

1. Define a tool with needsApproval: true
2. User sends a message that triggers the tool
3. Tool approval card appears, user clicks "Approve"
4. Tool executes successfully on the server (verified via database state)
5. Frontend tool part stays at approval-responded state indefinitely
6. UI shows spinning "Executing..." forever
7. Only when user sends a NEXT message does beforeTurn clean up the stale state

Expected Behavior

After approval, the continuation should:

1. Execute the tool
2. Update the tool part state to output-available with the tool output
3. Stream the result back to the frontend
4. UI transitions from "Executing..." to "Complete" with output

Actual Behavior

• Server-side: Tool executes correctly, state changes persist
• Frontend: Tool part stays at approval-responded, never receives output-available
• The continuation stream appears to not reach the frontend

WebSocket Evidence

After user approves the tool, the cf_agent_chat_messages broadcast shows the tool part stuck at:

{
  "toolName": "updateTrigger",
  "state": "approval-responded",
  "approval": { "id": "...", "approved": true }
}

No subsequent cf_agent_message_updated or stream chunk updates the state to output-available.

Workaround

In our beforeTurn override, we clean up stale approval-responded parts on the next non-continuation turn. This means the state only resolves when the user sends another message, not immediately after approval.