WarpGrep might nail basic string matches, but if your auth logic is spread across modules with no obvious keywords, it willl choke hard...I dont think their mcp still supports semantic search ..they promised they might add in future ig.. . For big repos (think 100k+ LOC), you'd need hybrid retrieval with BM25 + dense vectors, maybe FAISS/HNSW indexing, AST chunking... Without it, refactoring auth means manual hunts or praying the agents don't hallucinate paths..this is the secret sauce to one shot features or refactor.. otherwise u have to spend hours of debugging..