Prevent duplicate messages when using addToolApprovalResponse

[Muhammad-Bin-Ali]

Resolves #790

Summary

Fixes duplicate assistant messages when using addToolApprovalResponse with tools that have needsApproval: true.

Problem

When a user approves a tool via addToolApprovalResponse and then calls sendMessage(), two assistant messages are persisted with the same toolCallId:

• Original message with server-generated ID (assistant_xxx) stuck in input-available state
• New message with client-generated ID in approval-responded state

Solution

Wrap addToolApprovalResponse in useAgentChat to notify the server via a new CF_AGENT_TOOL_APPROVAL message type. The server updates the message in place using the existing ID, preventing duplicates when sendMessage() is called.

Changes

• Add CF_AGENT_TOOL_APPROVAL message type in types.ts
• Add _applyToolApproval server method to update message in place in index.ts
• Wrap addToolApprovalResponse in useAgentChat to notify server first in react.tsx

Testing

To test this fix, use the reproduction example on branch reproduce/duplicate-message-needsApproval:

git checkout reproduce/duplicate-message-needsApproval
cd examples/approval-bug-repro
npm install
npm run dev

1. Click "Send Test Message" to trigger a tool call
2. Click "Approve" to call addToolApprovalResponse
3. Check the "Server Persisted Messages" panel - should show only one message per toolCallId

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commit: b359a7e

[claude]

Claude Code Review

Overall Assessment: Strong implementation with comprehensive test coverage. One race condition needs addressing.

Issues Found

Critical: Race Condition in _applyToolApproval (index.ts:2086-2095)

The synchronous SQL update followed by reload creates a race window. Between SQL execution and reload, another client could modify messages, causing lost updates or stale state.

Fix: Add await to the SQL query at line 2087.

Minor: Potential Stale Message in Broadcast (index.ts:2108-2114)

After reloading messages, you call _findMessageByToolCallId again. You could use the already-updated message from line 2079 instead.

Strengths

• Comprehensive test coverage (6 test cases covering edge cases)
• Handles streaming messages correctly by checking _streamingMessage first
• Proper retry logic with backoff for race conditions
• Good documentation and comments
• Follows existing patterns for message updates

Architecture Alignment

• Correctly uses MessageType enum pattern
• Follows existing _apply method conventions
• Properly sanitizes messages before persistence
• Uses _broadcastChatMessage for multi-client sync

PR resolves #790 effectively.

[threepointone]

add a changeset
add some tests
ask opencode if the claude code review feedback is valid, and if so, to address the valid ones

[changeset-bot]

🦋 Changeset detected

Latest commit: b359a7e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@cloudflare/ai-chat	Patch
agents	Patch

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