Live app: https://legacy-lens-production-aab7.up.railway.app/
Legacy Lens is a RAG-powered assistant for the original Doom (1993) C source code. Ask questions in natural language and get answers grounded in the codebase, with citations to specific files and line ranges.
- Natural language Q&A — Ask things like "Where is the rendering loop?" or "How does the player move?" and receive answers backed by retrieved source excerpts.
- Grounded answers — All answers cite
file_path:start_line-end_line; the model is instructed not to invent symbols or line numbers. - Hybrid search — Combines vector similarity (embeddings) with full-text search for better retrieval.
- Interactive & Deep modes — Interactive for fast queries; Deep expands the query and retrieves more context for complex questions.
Example eval report: eval-report.md
Submission docs: RAG Architecture · Pre-Search · AI Cost Analysis
- Vector DB: pgvector (Postgres)
- Embeddings: OpenAI text-embedding-3-small
- LLM: gpt-4.1-nano
- Chunking: tree-sitter (syntax-aware, function/struct/typedef boundaries)
- Deployment: Railway