explain-codebase— agent skill

Build a navigable map of this repository so the reader can find their way around and start contributing. Work from evidence in the repo, not assumptions about the stack.

Orient first

• Identify the project type and stack from manifests and config (e.g. package.json, pyproject.toml, go.mod, Cargo.toml, pom.xml, Gemfile, Dockerfiles, CI config). Note the build, test, and run commands.
• Read the README, docs, and any CONTRIBUTING or architecture notes before reading code, but verify their claims against the tree rather than trusting them blindly.
• Get the shape of the tree: the top-level directories and what each is responsible for.

Map the architecture

• Find the entry points: CLI mains, server bootstraps, route registrations, scheduled jobs, queue consumers, lambda/handler exports, UI roots. List them with file:line.
• Identify the layers / modules and how they depend on each other (e.g. interface → service/domain → data access → external integrations). Note the boundaries that matter.
• Locate cross-cutting concerns: config/env loading, auth, logging, error handling, database/connection setup, feature flags.

Trace the data flow

• Pick one or two representative operations (or whatever the user asked to focus on) and follow them end to end: input → validation → core logic → persistence/external calls → response.
• Show each path as a short sequence of file:line hops the reader can click through.
• Call out where state lives (databases, caches, queues, external services) and how it's accessed.

Report

Produce, concisely:

1. Summary: one paragraph on what this project is and does.
2. Architecture map: the layers/modules and their responsibilities.
3. Entry points: where execution starts, with paths.
4. Key flows: the traced paths.
5. Conventions & gotchas: naming, patterns, where to add a new feature, anything surprising.
6. Where to look next: the 3 to 5 files most worth reading first.

Prefer precise file:line references over prose. Flag anything you were unsure about rather than guessing.