| name | explain-codebase |
| description | Onboard to an unfamiliar codebase by mapping its architecture, entry points, and data flow. Use when starting work in a new or unknown repository and you need a navigable mental model fast. |
| argument-hint | (optional) a subsystem, feature, or question to focus on |
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:
- Summary: one paragraph on what this project is and does.
- Architecture map: the layers/modules and their responsibilities.
- Entry points: where execution starts, with paths.
- Key flows: the traced paths.
- Conventions & gotchas: naming, patterns, where to add a new feature, anything surprising.
- 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.
