Map Codebase

Overview

A methodical exploration workflow that produces an evidence-cited map of a codebase area. Replaces ad-hoc grep with a disciplined four-step pass: scope, list, read, diagram. The output is a short artifact you can attach to a plan or design doc — file paths, line numbers, call directions, and the questions you couldn't answer from reading. The skill's value is enforcing that every claim about the code is backed by a specific file:line citation, not a memory or pattern-match. Senior ICs and tech leads use it to bound the blast radius of a change before they propose it.

When to Use

• Before writing a plan that touches more than one module
• When inheriting a codebase area you didn't author
• When a teammate asks "how does X work" and you don't have a confident answer with citations
• Before a refactor, to enumerate everything that calls the code you're about to change
• When debugging crosses a boundary you don't fully understand (auth, ORM, framework internals)