Codebase MCP Server

# Task 1.4 Completion Summary: Config File Discovery Implementation ## Task Overview Implemented config file discovery logic with upward directory traversal for automatic project switching in the codebase-mcp server. ## Files Created ### 1. `/Users/cliffclarke/Claude_Code/codebase-mcp/src/auto_switch/discovery.py` **Lines of Code**: 89 **Purpose**: Implements config file discovery with upward directory traversal **Key Features**: - Symlink resolution with error handling - Upward directory traversal (configurable max depth, default 20 levels) - Filesystem root detection (prevents infinite loops) - Permission error handling (continues search on access errors) - Comprehensive logging for debugging **Type Safety**: - Full type annotations with `from __future__ import annotations` - Returns `Optional[Path]` for clear None handling - mypy --strict compliant (zero type errors) **Constitutional Compliance**: - Principle 2 (Local-First): No network calls, filesystem-only - Principle 5 (Production Quality): Comprehensive error handling - Principle 8 (Type Safety): Complete type annotations ### 2. `/Users/cliffclarke/Claude_Code/codebase-mcp/scripts/validate_discovery.py` **Lines of Code**: 156 **Purpose**: Comprehensive validation test suite for discovery logic **Test Coverage**: 1. Config found in working directory 2. Config found in parent directory (upward traversal) 3. Config not found (returns None) 4. Max depth limit enforcement 5. Symlink resolution ## Implementation Details ### Algorithm ``` 1. Start from working_directory (with symlink resolution) 2. Check for .codebase-mcp/config.json in current directory 3. Move to parent directory if not found 4. Stop at: config found, filesystem root, or max_depth ``` ### Error Handling - **Symlink resolution failures**: Logs warning, continues with unresolved path - **Permission errors**: Logs warning, continues search in parent directories - **Filesystem root detection**: Prevents infinite loops by checking `parent == current` ### Performance - O(n) where n = min(max_depth, distance_to_root) - Single filesystem check per directory level - No recursive calls (iterative implementation) ## Validation Results ### Test Suite Execution ```bash uv run python scripts/validate_discovery.py ``` **Result**: ✓ ALL VALIDATION TESTS PASSED (5/5 tests) ### Test Details #### Test 1: Config in Working Directory - **Status**: ✓ PASSED - **Validation**: Config found at level 0 (immediate discovery) #### Test 2: Config in Parent Directory - **Status**: ✓ PASSED - **Validation**: Traversed 3 levels upward to find config #### Test 3: Config Not Found - **Status**: ✓ PASSED - **Validation**: Correctly returned None when no config exists #### Test 4: Max Depth Limit - **Status**: ✓ PASSED - **Validation**: - max_depth=3 correctly stops search (config at level 5) - max_depth=10 correctly finds config (config at level 5) #### Test 5: Symlink Resolution - **Status**: ✓ PASSED - **Validation**: Successfully resolved symlink and found config in real directory ### Type Safety Validation ```bash uv run mypy --strict src/auto_switch/discovery.py ``` **Result**: ✓ ZERO TYPE ERRORS **Type Coverage**: - Function signature: Complete with `Optional[Path]` return - Parameter types: `Path` and `int` with defaults - Variable types: All inferred correctly from annotations - Error handling: Proper exception type annotations ## Integration Notes ### Usage Example ```python from pathlib import Path from src.auto_switch.discovery import find_config_file # Basic usage config_path = find_config_file(Path("/path/to/project/subdir")) # Custom max depth config_path = find_config_file(Path("/path/to/project"), max_depth=10) # Handle not found if config_path is None: print("No config found") else: print(f"Config found at: {config_path}") ``` ### Logging Output ``` INFO: Found config at /path/to/project/.codebase-mcp/config.json (level 2) WARNING: Cannot access /restricted/.codebase-mcp/config.json: Permission denied DEBUG: Reached filesystem root without finding config ``` ## Dependencies ### Runtime Dependencies - Python 3.11+ - `pathlib` (stdlib) - `typing` (stdlib) - `logging` (stdlib) ### Development Dependencies - `mypy` (type checking) - `pytest` (future unit tests) ## Future Enhancements ### Potential Improvements 1. **Caching**: Cache discovered configs to avoid repeated filesystem traversals 2. **Watch mode**: File system watch for config changes 3. **Alternative names**: Support multiple config file names (config.yaml, etc.) 4. **Validation**: Validate config schema during discovery ### Performance Optimization - Current performance is optimal for typical project structures - Average case: 2-3 filesystem checks (config typically near project root) - Worst case: max_depth filesystem checks (configurable, default 20) ## Compliance Checklist ### Constitutional Principles - [x] Principle 2: Local-First Architecture (no cloud dependencies) - [x] Principle 5: Production Quality (comprehensive error handling) - [x] Principle 8: Type Safety (mypy --strict compliant) - [x] Principle 11: FastMCP Foundation (compatible with FastMCP context) ### Code Quality Standards - [x] Complete type annotations - [x] Comprehensive docstrings - [x] Error handling for edge cases - [x] Logging for observability - [x] Test coverage (5/5 scenarios) ### Documentation - [x] Function docstrings with examples - [x] Algorithm description - [x] Parameter documentation - [x] Return value documentation - [x] Validation test suite ## Conclusion **Status**: ✅ COMPLETE AND VALIDATED The config file discovery implementation is production-ready with: - Complete type safety (mypy --strict compliant) - Comprehensive error handling - 100% test coverage of specified scenarios - Constitutional compliance - Performance optimization (iterative algorithm) - Clear logging for debugging **Next Step**: Proceed to Task 1.5 (Implement config validation) --- **Implementation Date**: 2025-10-16 **Validation Date**: 2025-10-16 **Developer**: Claude Code (python-wizard subagent)