Make collect context tool production-ready

[Christian-Devora]

Pull Request

Description

This Pull Request introduces a comprehensive overhaul of the collect_context tool, making it fully production-ready, highly debuggable, and functionally robust. The changes address critical bugs related to Git awareness, globbing, .gitignore support, truncation, binary file handling, path limits, and caching correctness. Additionally, the PR includes extensive unit and integration tests, updated documentation for MCP Inspector usage, and a detailed debug report.

The primary motivation is to enhance the reliability, security, and diagnostic capabilities of the collect_context tool, ensuring it provides accurate and relevant context to the AI assistant while being easy to troubleshoot in production environments.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring
• Test improvements

Related Issues

Fixes # (issue number)
Closes # (issue number)
Related to # (issue number)

Changes Made

• MCP Inspector Setup: Created examples/inspector-stdio.json and examples/inspector-stdio-local.json for easy debugging with MCP Inspector. Added inspect:stdio script to package.json.
• Diagnostic Logging & Flags: Implemented verbose internal diagnostics behind CONTEXT_DEBUG=1 environment flag. Each request now emits a unique traceId included in all logs and the response's meta object.
• Structured Result Summary: The collect_context tool now returns a structured result including files, bytes, truncated, cacheKey, and a meta object with traceId, strategy, usedGit, elapsedMs, and notes.
• Git Awareness: Enhanced strategy="changed" to use git diff --name-only HEAD, with robust error handling for non-git repositories or empty changes. Detects current HEAD SHA for cache key generation.
• Glob & .gitignore: Integrated the ignore library to respect .gitignore rules. Added default excludes for node_modules, .git, and common binary files. Supports include[] and exclude[] glob patterns with POSIX path normalization.
• Limits & Truncation: Strictly enforces maxKB and maxFiles. Implemented a per-file hard cap (256KB) and sets truncated=true with notes in the response when limits are hit.
• Binary & Encoding Safety: Detects and skips binary files (heuristic/extension-based). Assumes UTF-8 encoding and skips files if decoding fails.
• Caching: Implemented an in-memory LRU cache keyed by {cwd, headShaOrNone, argsHash} with a 10-minute TTL. Cache hits are surfaced in meta.
• Security: Added path traversal guards to restrict operations to the cwd subtree and reject absolute paths outside cwd. Redacts secrets in error messages and never emits file contents in logs.
• Testing: Created comprehensive unit tests (test/tools/collectContext.test.ts) covering all new features and edge cases. Developed integration tests (test/integration/collectContext.git.test.ts) using a temporary git repository and fixtures (test/fixtures/mini-repo/) for realistic scenarios. Added test:context and test:context:git npm scripts.
• Documentation: Created docs/inspector-playbook.md with step-by-step instructions for using MCP Inspector. Updated README.md with an "Inspector (stdio) Quick Start" and a "Troubleshooting (Context Tool)" section.
• Debug Report: Delivered docs/context-debug-report.md summarizing findings, fixes, and any remaining edge cases.
• Error Handling: Standardized user-facing error messages for common scenarios like "No git history detected" or "Requested path is outside workspace". Improved handleError and redactSecrets for robustness.

Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed (via running all tests and verifying outputs)

Test Results

pnpm test
> devora-prompt-assistant-mcp@1.0.0 test /workspace
> vitest run

 RUN  v0.34.6 /workspace/test/tools/collectContext.test.ts (15)
 RUN  v0.34.6 /workspace/test/integration/collectContext.git.test.ts (8)


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Documentation

• README.md updated
• CHANGELOG.md updated (Not applicable for this initial PR)
• JSDoc comments added/updated (Code comments were added/updated)
• Code comments added/updated

Breaking Changes

None. The public contract of the collect_context tool remains compatible, with added fields in the response for enhanced diagnostics.

Checklist

Code Quality

• Code follows project style guidelines
• Self-review completed
• Code is properly commented
• No console.log statements left in code (Debug logs are behind CONTEXT_DEBUG env flag)
• Error handling is appropriate

Testing

• All tests pass
• New tests cover new functionality
• Edge cases are tested
• Error conditions are tested

Documentation

• Public APIs are documented (via JSDoc and README)
• README examples are updated
• Breaking changes are documented (N/A)
• Migration guide provided (N/A)

Security

• No sensitive data exposed (secrets redacted in logs/errors)
• Input validation is appropriate
• Error messages don't leak sensitive information
• Dependencies are secure (only ignore added, which is tiny and widely used)

Additional Notes

This PR represents a significant step towards making the collect_context tool robust and production-ready. The focus has been on comprehensive debugging capabilities, reliable file collection logic, and strong security measures. The new CONTEXT_DEBUG=1 flag, combined with the traceId in responses and logs, provides an unparalleled ability to diagnose and troubleshoot issues in real-time.

Reviewer Notes

Please pay close attention to:

1. Diagnostic Logging: Verify the clarity and completeness of logs when CONTEXT_DEBUG=1 is enabled.
2. Git Integration: Review the logic for strategy="changed" and error handling for non-git scenarios.
3. .gitignore and Filtering: Ensure .gitignore rules are correctly applied and default binary/large file exclusions work as expected.
4. Security Guards: Check the path traversal and absolute path rejection logic.
5. Test Coverage: Review the new unit and integration tests for thoroughness and correctness.
6. Documentation: Confirm the README.md and docs/inspector-playbook.md are clear and accurate.

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[cursor]

Bug: Git History Present But No Modified Files

Using strategy='changed' in collectContext throws a ValidationError when no files are modified in a git repository. The error message "No git history detected" is misleading, as git history is present, but no files are currently changed. This should return an empty context instead of an error, as having no modified files is a valid state.

 

[cursor]

Bug: Redundant Path Traversal Check

The path traversal check using normalizedPath.includes('..') is overly broad, incorrectly blocking legitimate filenames that contain '..'. A more robust security check using relative() already handles actual path traversal, making this initial check redundant.