/onboard - Codebase Onboarding

Understand any codebase in minutes. Generates a developer guide with architecture, conventions, key modules, and getting-started instructions.

Target: $ARGUMENTS

When to Use

First day on a new project or team
Picking up an open-source project for the first time
Reviewing a project before a technical interview
Before contributing to an unfamiliar repo
When documentation is missing or outdated
NOT for: projects you already know well (use @scout for quick checks instead)

Workflow

Step 1: Project Discovery

Scan the project root:

Read: package.json / pyproject.toml / go.mod / Cargo.toml
Read: README.md (if exists)
Read: ARCHITECTURE.md / CLAUDE.md / CONTRIBUTING.md (if exist)
Scan: Top-level directory structure

Extract:

Project name and description
Language and framework
Package manager and scripts
Entry points

Step 2: Architecture Mapping

Map the project structure:

Identify:
  - Source root (src/, app/, lib/)
  - Module/feature boundaries
  - Shared utilities
  - Configuration files
  - Test structure
  - CI/CD setup

Generate architecture diagram:

src/
├── modules/          → Feature modules (users, orders, products)
│   └── [module]/
│       ├── types/    → TypeScript interfaces
│       ├── services/ → Business logic
│       ├── hooks/    → State management
│       └── components/ → UI components
├── shared/           → Shared utilities
├── config/           → App configuration
└── app/              → App entry and routing

Step 3: Convention Detection

Detect coding conventions by reading actual files:

Convention	How to Detect
Naming	Read 3-5 files, check function/variable naming
File structure	Map actual directory patterns
State management	Find store/state imports (Redux, Zustand, Pinia, etc.)
API layer	Find HTTP client usage (axios, fetch, etc.)
Testing	Find test files, check framework (Jest, Vitest, etc.)
Styling	Find CSS/styled imports (Tailwind, CSS Modules, etc.)
Error handling	Find try/catch patterns, error boundaries
Imports	Check for path aliases, barrel exports

Step 4: Key Module Analysis

For each major module/feature:

Module: [name]
├── Purpose: [what it does]
├── Files: [count]
├── Dependencies: [what it imports from]
├── Dependents: [what imports from it]
├── Entry point: [main file]
└── Tests: [yes/no, coverage estimate]

Focus on the 3-5 most important modules.

Step 5: Developer Guide Generation

Compile everything into an actionable guide.

Verification Protocol

Before claiming onboarding is complete:

Architecture diagram was generated from actual file structure (not assumed)
Conventions were detected from reading real code (not README claims)
At least 3 key modules were analyzed
Setup instructions were verified by checking scripts in package.json
If tests exist, the test command was identified

Anti-Rationalization

Excuse	Reality
"README explains everything"	READMEs are often outdated. Verify against actual code.
"Architecture is obvious"	Obvious to maintainers, not newcomers. Map it explicitly.
"Too many files to analyze"	Focus on top 3-5 modules. Don't skip the mapping step.
"No tests to analyze"	That IS the finding. Report it in the guide.
"Conventions aren't consistent"	Document the inconsistencies. It's useful for the developer.

Rules

Read actual code - Never rely solely on README or documentation
Map before explaining - Architecture diagram first, then details
Focus on key modules - 3-5 most important, not all of them
Detect, don't assume - Conventions come from reading files, not guessing
Be honest about gaps - Missing tests, docs, or conventions are findings too
Actionable output - Every section should help the developer start working

Output

──── /onboard ────
Project: [name]
Stack: [language + framework + key libraries]

Architecture:
[directory tree diagram]

Conventions:
  Naming: [camelCase / snake_case / PascalCase]
  State: [Redux / Zustand / Pinia / Context]
  API: [axios / fetch / tRPC]
  Testing: [Jest / Vitest / Playwright]
  Styling: [Tailwind / CSS Modules / styled-components]

Key Modules:
  1. [module] - [purpose] ([X files])
  2. [module] - [purpose] ([X files])
  3. [module] - [purpose] ([X files])

Getting Started:
  Install: [command]
  Dev: [command]
  Test: [command]
  Build: [command]

Notes:
  - [important observations]
  - [potential gotchas]
  - [missing documentation areas]

onboard