Semantic Search MCP Server

# Spec 003: Incremental Refresh **Status:** Planned **Target Version:** v0.3 ## Summary Instead of full re-indexing on changes, use git-diff to identify changed files and only re-embed those. Reduces refresh time from minutes to seconds on large repos. ## Acceptance Criteria - [ ] `git diff --name-only <last-indexed-commit>` identifies changed files - [ ] Only changed files are re-chunked and re-embedded - [ ] Deleted files have their vectors and FTS entries removed - [ ] Renamed files handled correctly (delete old, insert new) - [ ] `index(force_rebuild=True)` still triggers full rebuild - [ ] Staleness threshold: configurable via `SEMANTIC_SEARCH_STALE_MINUTES` (default: 60) ## API / Tool Surface No new tools. `status()` reports last-indexed commit hash. ## Edge Cases - Non-git repo: fall back to mtime-based staleness check - Merge commits: diff against merge base - Binary files changed: skip (already filtered) - Very large diff (>1000 files): full rebuild is cheaper ## Out of Scope - Tracking untracked files (outside git) — mtime fallback handles this - Submodule support ## Test Plan - `tests/test_incremental.py` — modify one file, verify only that file re-indexed - Verify deleted file vectors removed from LanceDB - Verify non-git repo falls back to mtime