Reuse first

Every duplicate is a future divergence. A bug fixed in one copy stays broken in the other.

Greenfield with no codebase to search yet. Run project-discovery first, then come back here.

3-layer search

Exact name often misses it, so search in three passes:

1. Name layer: grep -r "functionName", exact + camelCase + snake_case variants
2. Behavior layer: grep for what it does, format.*date, validate.*email, parse.*currency
3. Reference layer: find a feature that uses the thing you are looking for. Open it, follow its imports

You are done when you have printed what each layer returned. Write these three lines before you write anything: