RepoLens is a local-first RAG engine for OSS contributors. It answers questions about any repository using only the checked-out code — every answer sentence cites a file:line-range span, every citation is re-verified against the file on disk, and a per-answer grounding score tells you how well the answer is supported. It also detects where documentation has drifted from the code.

Why RepoLens

• Grounded, not guessed. Answers cite verifiable file:line spans. If the code doesn't contain the answer, RepoLens says so instead of hallucinating from model memory.
• Code-native retrieval. Source is parsed with tree-sitter into semantic units, embedded with a code-aware model, and retrieved with hybrid dense + BM25 search, reranking, and caller/callee graph expansion.
• Doc-drift detection. A dedicated mode flags doc claims that the code contradicts or no longer supports — CI-compatible with a non-zero exit on new findings.

Quick install

pip install repolens-rag
export GROQ_API_KEY=gsk_...         # free key: https://console.groq.com/keys

Or run it fully containerised:

GROQ_API_KEY=gsk_... docker compose up   # then open http://localhost:8000

Quickstart

repolens index ./path/to/repo      # index a local repository
repolens ask "how does routing work?" --repo <id>
repolens drift --repo <id>         # find stale documentation
repolens serve                     # launch the web UI at http://localhost:8000

See the Quickstart guide for the full walkthrough.

Architecture

Browser (React)
    │  HTTP ↓   ↑ SSE
FastAPI server
    ├── Ingestion   git walker → tree-sitter → chunker → graph → embedder + BM25 → storage
    ├── Retrieval   storage → hybrid (dense + BM25) → RRF → reranker → graph expander
    ├── Generation  chunks → grounded prompt → LLM → citation validator → grounding scorer
    └── Drift       storage → claim extractor → NLI entailment → markdown report

Full details in docs/ARCHITECTURE.md.

Documentation

• Quickstart
• Configuration
• API reference
• Architecture
• Tech stack
• Contributing

License

MIT