Fix #5162: Enhanced VS Code Language Model content filtering error handling

[roomote]

Summary

This PR fixes issue #5162 where VS Code Language Model API responses were getting filtered with unhelpful error messages like "response got filtered FIX!!".

Problem

The VS Code Language Model API applies content filtering/safety mechanisms that can reject responses, but the current error handling in the VS Code LM provider only specifically handled vscode.CancellationError. When content filtering occurred, these errors were not properly detected and handled, leading to generic error messages instead of helpful guidance for users.

Solution

Enhanced the error handling in the VS Code Language Model provider (src/api/providers/vscode-lm.ts) by:

1. Added content filtering detection: Implemented two new helper methods:

   • isContentFilteringError() - Detects filtering patterns in Error objects
   • isContentFilteringErrorObject() - Detects filtering patterns in error-like objects

2. Pattern-based detection: Both methods check for keywords like:

   • 'filtered', 'content policy', 'inappropriate', 'safety', 'blocked', etc.
   • Case-insensitive matching for robust detection

3. Enhanced error messages: When content filtering is detected, provides clear, actionable error messages that:

   • Explain that the content was filtered by VS Code's safety mechanisms
   • Suggest trying to rephrase the request
   • Maintain user-friendly guidance

4. Comprehensive test coverage: Added extensive test suite (src/api/providers/__tests__/vscode-lm-content-filtering.test.ts) with 11 test cases covering:

   • Various content filtering error scenarios
   • Case-insensitive detection
   • Both Error objects and plain error objects
   • Proper error message formatting

Changes

• Modified: src/api/providers/vscode-lm.ts

  • Enhanced createMessage() method error handling (lines 456-504)
  • Added isContentFilteringError() helper method
  • Added isContentFilteringErrorObject() helper method

• Added: src/api/providers/__tests__/vscode-lm-content-filtering.test.ts

  • Comprehensive test suite for content filtering detection
  • 11 test cases covering various scenarios
  • Ensures robust error handling and user-friendly messages

Testing

All tests pass, including:

• ✅ Existing VS Code LM provider tests
• ✅ New content filtering detection tests
• ✅ Linting and type checking across all packages

Impact

• User Experience: Users will now receive clear, helpful error messages when content is filtered
• Debugging: Easier to identify and resolve content filtering issues
• Backward Compatibility: Maintains existing error handling for cancellation and other error types
• Robustness: Case-insensitive pattern matching ensures reliable detection

Fixes #5162

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Important

Enhanced error handling for content filtering in VS Code Language Model API with new detection methods and improved error messages.

• Error Handling:
  • Added isContentFilteringError() and isContentFilteringErrorObject() in vscode-lm.ts to detect content filtering errors.
  • Enhanced createMessage() in vscode-lm.ts to provide clear error messages for content filtering.
• Testing:
  • Added vscode-lm-content-filtering.test.ts with 11 test cases for content filtering detection and error message validation.
• Misc:
  • Improved error message clarity and user guidance when content is filtered.

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[delve-auditor]

✅ No security or compliance issues detected. Reviewed everything up to 186fe01.

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• 🔎 Scanned files: 2 changed file(s)

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