Install any skill in seconds. Free to start, no credit card required.
Get Started Free →Systematically map an unfamiliar codebase before changing it — entry points, build/test loop, conventions, data flow. Use when starting work in a repo you haven't seen, or asked "how does this codebase work?".
| Test case | Without → With | Effect | Δ tokens | Δ turns |
|---|---|---|---|---|
| case-04 | ✗→✓ | ▲ Improved | -14% | 0% |
| case-06 | ✗→✓ | ▲ Improved | -3% | 0% |
| case-19 | ✗→✓ | ▲ Improved | -19% | 0% |
| case-22 | ✓→✗ | ▼ Worse | -26% | 0% |
| case-07 | ✓→✓ | = Same ✓ | 4% | 0% |
Resist editing until you can answer: how do I run it, how do I test it, where does the change go, and what style does this house write in?
README.md, then the manifest(package.json / pyproject.toml / go.mod / Cargo.toml): name, scripts, dependencies. The scripts block is the repo telling you its verbs.
bin/main fields, src/index.*, cmd/,__main__.py. Trace one request/command end-to-end at skim depth — names only, no line-reading.
record how long it takes and whether it's green at HEAD. A red baseline changes everything you conclude later.
that are generated/vendored so you never read them again.
(git log --name-only -10): error handling pattern, naming, comment density, test structure. Your changes should be indistinguishable from these.
the one module everything imports? That module is load-bearing — changes there need the most care.
CONTRIBUTING.md, CLAUDE.md, .github/workflows (what CI actually enforces), lint configs.
Write a short map (10–20 lines) before starting the actual task:
run: npm start (src/cli.js) test: npm test, ~6s, green at HEAD
flow: cli.js → commands/* → store.js (all persistence) → index.json
style: ESM, no deps, errors thrown as plain Error, tests in test/*.test.js
care: store.js is imported everywhere; schema changes ripple
rules: CI runs lint+test on 3 OS; commits are conventionalKeep it honest — list what you didn't look at, so later-you knows where the map has blank spots.
Other measured skills in the registry, with their headline benchmark lift.