[Graphite MQ] Draft PR GROUP:spec_733614 (PRs 1412)

[graphite-app]

This draft PR was created by the Graphite merge queue.
Trunk will be fast forwarded to the HEAD of this PR when CI passes, and the original PRs will be closed.

The following PRs are included in this draft PR:

• #1412

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Project	Deployment	Preview	Comments	Updated (UTC)
rivetkit-next-js-max	Ready	Preview	Comment	Oct 20, 2025 3:24am
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[claude]

Code Review

This PR improves logging and error handling around the engine binary download process. Overall, the changes are solid and improve the user experience. Here's my detailed feedback:

✅ Strengths

1. Race Condition Fix: Using randomUUID() instead of process.pid for temp files is a good improvement that prevents conflicts when multiple processes download simultaneously.

2. Better User Experience: The 5-second timeout warning is helpful for users on slow connections.

3. Enhanced Debugging: Added structured logging with file size, download duration, and content-length makes troubleshooting easier.

4. Proper Error Cleanup: The try-catch block ensures temp files are cleaned up on download failure.

5. User-Friendly Error Messages: Including GitHub issues and Discord links in error messages helps users get support.

🔍 Suggestions & Concerns

1. Missing Import Validation

The randomUUID import is added but not used in the existing codebase pattern. This is fine, but consider:

• Node.js v14.17.0+ is required for randomUUID. Verify your package.json engines field supports this.

2. Potential Race Condition Still Exists

While the unique temp file prevents download conflicts, there's still a window between checking fileExists(binaryPath) (line 147) and starting the download where two processes could both decide to download. Consider using a lock file pattern or atomic operations:

// Check again after acquiring temp file
const binaryExists = await fileExists(binaryPath);
if (binaryExists) {
  await fs.unlink(tempPath);
  return;
}

3. Incomplete Download Detection

If the download is interrupted, the temp file is cleaned up, but there's no verification that the downloaded binary is complete and valid. Consider:

• Verify file size matches content-length header
• Add checksum verification if available
• Verify the binary is executable before renaming

Example:

const expectedSize = response.headers.get('content-length');
if (expectedSize && stats.size !== Number.parseInt(expectedSize)) {
  await fs.unlink(tempPath);
  throw new Error(`Download incomplete: expected ${expectedSize} bytes, got ${stats.size}`);
}

4. Hardcoded Timeout

The 5-second timeout is hardcoded. For large binaries or slow connections, this might be too aggressive. Consider:

• Making it configurable
• Basing it on content-length (e.g., warn if < 100KB/s)
• Showing download progress instead

5. Error Type Inconsistency

According to CLAUDE.md guidelines, errors should extend from ActorError, UserError, or InternalError from packages/core/src/actor/errors.ts. The thrown errors here are plain Error objects. Consider:

throw new InternalError('Engine binary download failed', { 
  version, 
  url: downloadUrl 
});

6. Test Coverage Missing

No tests exist for downloadEngineBinaryIfNeeded or ensureEngineProcess. Consider adding:

• Unit tests for download success/failure scenarios
• Tests for race conditions with parallel downloads
• Tests for slow download warnings
• Tests for cleanup on errors

7. Minor: Log Message Consistency

Line 107: "engine process exited, please report this error" - but an exit isn't always an error (could be graceful shutdown). Consider checking the exit code:

const isError = code !== 0 || signal !== null;
logger()[isError ? 'warn' : 'info']({
  msg: isError 
    ? 'engine process exited unexpectedly, please report this error'
    : 'engine process exited',
  code,
  signal,
  ...(isError && {
    issues: 'https://github.com/rivet-dev/rivetkit/issues',
    support: 'https://rivet.dev/discord',
  }),
});

🎯 Performance Considerations

• The changes are performant. No blocking operations added.
• The timeout warning runs asynchronously and doesn't block the download.

🔒 Security Considerations

• Temp File Security: Using UUID prevents predictable temp file names, which is good.
• File Permissions: Good that permissions are set before rename (line 202-204).
• Consider: Add validation that binaryPath is within expected directory to prevent path traversal.

📋 Action Items

High Priority:

1. Add download integrity verification (content-length check at minimum)
2. Add test coverage for download scenarios

Medium Priority:
3. Use proper error types from packages/core/src/actor/errors.ts
4. Improve exit code handling to distinguish errors from graceful shutdowns
5. Consider lock file pattern for preventing parallel downloads to same binary

Low Priority:
6. Make timeout configurable or show progress
7. Add path validation for binaryPath

Summary

This is a solid improvement to the codebase that enhances observability and handles edge cases better. The main concerns are around download integrity verification and test coverage. The changes follow most of the project's guidelines but could align better with the error handling patterns.

Recommendation: Approve with suggested improvements for future PRs, particularly around download verification and testing.