Cheap whole-project overview: file/language counts and the most important modules ranked by dependency centrality (PageRank). Call this FIRST in a new session instead of exploring folders.

Everything Cerebro knows about a file WITHOUT reading it: cached summary (with staleness flag), defined symbols, and dependency edges.

Find relevant files. When the semantic index is built it ranks by meaning (intent), so phrase queries naturally ("where do we validate stock at checkout?"); it also includes keyword/symbol matches. Returns paths to cerebro_get().

Leave a trace: store your English understanding of a file so future sessions reuse it instead of re-analyzing. Write 1-3 dense sentences in English describing what the file does and its role.

What the index no longer trusts: files changed/added/deleted on disk since the last reindex, plus summaries whose source file has changed.

Catch changes made outside Claude Code (branch switch, git pull, edits in the raw editor) and reindex only the affected files. Works across nested repos.

Refresh the static index (symbols, dependency edges, hashes). Only changed/new/deleted files are reprocessed. Pass paths to limit scope.

Record a decision, domain rule, or gotcha — the why that reading code can never recover (e.g. 'QR_MANUAL = merchant confirms payment by hand', 'Seller was refactored to Organization'). Future sessions retrieve it with cerebro_recall. Keep content to 1-3 sentences; topic is an optional short tag.

Recall decisions/rules/gotchas recorded by past sessions BEFORE re-deriving them. Pass a query to search by meaning of topic/content, or leave empty for the most recent notes.

Transitive blast radius: every file that directly OR indirectly imports path. Use before changing a widely-used file to see what could break.

Find circular import groups (files that mutually depend on each other) — an architecture smell worth breaking. Returns each cycle's members.

Find every call site of a function / method / class by NAME across the repo (symbol-level call graph; name-resolved, so it may include same-named symbols). Use to see who actually uses a symbol before you change it.

List the internal functions/methods a file calls — its outgoing call edges (name-resolved). External library calls are omitted.

List code files that nothing imports — dead-code candidates. Framework entrypoints (modules, controllers, pages, configs, tests) are listed separately since they're loaded by convention, not by import.

List unused-export candidates: functions/classes/methods whose name is referenced nowhere in the indexed code, inside files that ARE imported (the symbol-level dead code that cerebro_orphans, which works per-file, can't see). Heuristic — confirm before deleting: dynamic access (obj['x'], string-based DI) and reflection can make a used symbol look dead.

Backend HTTP endpoints (NestJS routes) the project exposes — the front↔back boundary that import edges miss. Search by path / method / handler (e.g. 'POST carts', 'promotions', 'findActive') to answer 'where is this endpoint handled?' without grepping decorators.