fix: coerce write_to_file content to string when model sends object

[roomote]

Related GitHub Issue

Closes: #11040

Description

This PR attempts to address Issue #11040 where some models (e.g., GLM 4.7 via OpenAI Compatible API) incorrectly pass the content parameter as a JSON object instead of a string when calling the write_to_file tool, causing processing to break silently.

Key implementation details:

• Added a new coerceContentToString() helper method in NativeToolCallParser.ts that handles type coercion gracefully
• Updated both parseToolCall() and createPartialToolUse() methods to use this helper for the write_to_file tool
• Added explicit warning logging when coercion occurs so users are not left in the dark about model misbehavior
• Follows the existing pattern for type coercion (e.g., coerceOptionalBoolean for booleans)

Feedback and guidance are welcome.

Test Procedure

1. Unit tests added: New test cases in NativeToolCallParser.spec.ts covering:

   • Normal string content (unchanged behavior)
   • Object content coerced to JSON string
   • Array content coerced to JSON string
   • Number content coerced to string
   • Streaming and finalization paths

2. Run tests:

   cd src && npx vitest run core/assistant-message/__tests__/NativeToolCallParser.spec.ts

3. Manual verification: With a model like GLM 4.7 that sends object content, the tool should now work instead of breaking silently, and a warning will be logged.

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue (see "Related GitHub Issue" above).
• Scope: My changes are focused on the linked issue (one major feature/fix per PR).
• Self-Review: I have performed a thorough self-review of my code.
• Testing: New and/or updated tests have been added to cover my changes (if applicable).
• Documentation Impact: I have considered if my changes require documentation updates (see "Documentation Updates" section below).
• Contribution Guidelines: I have read and agree to the Contributor Guidelines.

Documentation Updates

• No documentation updates are required.

Additional Notes

This is a defensive fix that gracefully handles model misbehavior without changing the expected interface. Models that correctly output strings are unaffected.

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Important

Adds content coercion to string for write_to_file tool in NativeToolCallParser.ts, with tests for various content types.

• Behavior:
  • Adds coerceContentToString() in NativeToolCallParser.ts to convert non-string content to JSON string for write_to_file tool.
  • Updates parseToolCall() and createPartialToolUse() in NativeToolCallParser.ts to use coerceContentToString().
  • Logs a warning when content coercion occurs.
• Tests:
  • Adds tests in NativeToolCallParser.spec.ts for write_to_file tool to verify content coercion from object, array, and number to string.
  • Tests cover normal, streaming, and finalization paths.

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Rooviewer   See task on Roo Cloud

Review completed. No issues found.

The implementation is clean and well-structured:

• Adds a coerceContentToString helper following the existing pattern of coerceOptionalBoolean
• Correctly handles string, object, array, and number content types
• Logs appropriate warnings when coercion occurs
• All 13 tests pass with comprehensive coverage

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