How it works

1. Resolve. Every lockfile in the project directory, and in monorepo roots above it for ecosystems not found yet, becomes a list of exact (ecosystem, name, version) triples. Direct dependencies are marked.
2. Locate. Each package's files are found on disk (see Ecosystems). If the installed version differs from the lockfile, the answer says so and shows the installed one; with fetching enabled it reads the pinned version instead.
3. Extract. Markdown and reStructuredText are split into heading-scoped sections (long ones at paragraph boundaries, never inside code fences). Source files are parsed with tree-sitter (TypeScript, Python, Rust, Go) into symbols with a signature (the declaration without its body), a cleaned doc comment, a qualified path and a line number.
4. Index. Each entry becomes weighted terms: names and headings count most, doc prose next, signatures and code examples least. The tokenizer keeps identifiers whole and also splits camelCase, snake_case and digits; a light stemmer and a short programming synonym table (dict/dump, parse/validate, error/exception, ...) bridge wording. The index is cached on disk per package, version and source location, so a version is indexed once.
5. Rank. BM25 fused with embedding similarity (a static model2vec model: a text's vector is the mean of its WordPiece token vectors, so embedding every symbol of Next.js takes well under a second), each normalized to its best hit. Then signals that matter for docs: entries whose name or heading contains a query word, identifiers written in the question (model_dump, z.object), changelog sections only when the question is about changes, and lower weight for private modules, bundled tooling and legacy copies. Deprecation notes among the top results ("use model_validate instead") lift the API they point to.
6. Pack. Results are added in rank order until the token budget is spent (the last one trimmed at a line boundary), each with a package@version path:line citation.

api is exact rather than ranked: it finds entries whose name matches the last segment of the symbol, scores qualifiers (Router in axum::Router::route), follows re-exports, and adds overloads, members and other matches.