feat: Implement adaptive RRF weights and query intent detection

- Added integration tests for adaptive RRF weights in hybrid search.
- Enhanced query intent detection with new classifications: keyword, semantic, and mixed.
- Introduced symbol boosting in search results based on explicit symbol matches.
- Implemented embedding-based reranking with configurable options.
- Added global symbol index for efficient symbol lookups across projects.
- Improved file deletion handling on Windows to avoid permission errors.
- Updated chunk configuration to increase overlap for better context.
- Modified package.json test script to target specific test files.
- Created comprehensive writing style guidelines for documentation.
- Added TypeScript tests for query intent detection and adaptive weights.
- Established performance benchmarks for global symbol indexing.

codex-lens/CHANGELOG.md

@@ -0,0 +1,41 @@
+# CodexLens – Optimization Plan Changelog
+
+This changelog tracks the **CodexLens optimization plan** milestones (not the Python package version in `pyproject.toml`).
+
+## v1.0 (Optimization) – 2025-12-26
+
+### Optimizations
+
+1. **P0: Context-aware hybrid chunking**
+   - Docstrings are extracted into dedicated chunks and excluded from code chunks.
+   - Docstring chunks include `parent_symbol` metadata when the docstring belongs to a function/class/method.
+   - Sliding-window chunk boundaries are deterministic for identical input.
+
+2. **P1: Adaptive RRF weights (QueryIntent)**
+   - Query intent is classified as `keyword` / `semantic` / `mixed`.
+   - RRF weights adapt to intent:
+     - `keyword`: exact-heavy (favors lexical matches)
+     - `semantic`: vector-heavy (favors semantic matches)
+     - `mixed`: keeps base/default weights
+
+3. **P2: Symbol boost**
+   - Fused results with an explicit symbol match (`symbol_name`) receive a multiplicative boost (default `1.5x`).
+
+4. **P2: Embedding-based re-ranking (optional)**
+   - A second-stage ranker can reorder top results by semantic similarity.
+   - Re-ranking runs only when `Config.enable_reranking=True`.
+
+5. **P3: Global symbol index (incremental + fast path)**
+   - `GlobalSymbolIndex` stores project-wide symbols in one SQLite DB for fast symbol lookups.
+   - `ChainSearchEngine.search_symbols()` uses the global index fast path when enabled.
+
+### Migration Notes
+- **Reindexing (recommended)**: deterministic chunking and docstring metadata affect stored chunks. For best results, regenerate indexes/embeddings after upgrading:
+  - Rebuild indexes and/or re-run embedding generation for existing projects.
+- **New config flags**:
+  - `Config.enable_reranking` (default `False`)
+  - `Config.reranking_top_k` (default `50`)
+  - `Config.symbol_boost_factor` (default `1.5`)
+  - `Config.global_symbol_index_enabled` (default `True`)
+- **Breaking changes**: none (behavioral improvements only).
+