Codebase Context Engineering for AI Agents: Repo Maps, AST Indexing, and Retrieval Architectures
Modern software repositories routinely contain hundreds of thousands or millions of lines of source code. A medium-sized production project with 500 files and 100,000 lines of code typically spans 3 million to 5 million tokens. While frontier models have expanded context windows to 200,000 tokens or more, stuffing an entire repository into a prompt remains fundamentally impractical. Beyond exponential inference costs and KV cache memory bloat, long-context attention suffers from severe retrieval


















