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Guide

Codebase Onboarding Skills

Build interactive tour skills and domain knowledge guides that help new team members navigate your architecture and code conventions.

~8 min read

Every engineering organization struggles with onboarding. You invite a new engineer to the repository, point them at a Confluence wiki that was last updated nine months ago, and tell them to read the code. Three days later, they are still struggling with local environment variables and wondering which database table stores user subscriptions.

Static onboarding documentation fails because code moves faster than wikis. But when you build an onboarding skill inside Claude Code, you give new team members an interactive guide that reads the live codebase, explains company domain jargon, and traces execution paths in real time.

Why conversational onboarding beats static documentation

An onboarding skill combines standing architectural facts with live codebase inspection:

You type: where is the user authentication flow handled in this codebase?
Output: User auth is handled in src/middleware/auth.ts (session extraction) and
Output: src/services/jwt.ts (token signature verification). Routes use the
Output: requireAuth hook defined in src/hooks/requireAuth.ts.
Note: Claude pinpoints the exact middleware chain in seconds.
New engineer asking architectural questions in a clean session.
  • Interactive Q&A: New hires can ask "where is the Stripe webhook handled?" and receive the exact file path along with the business rationale.
  • Always synchronized: Because Claude inspects the active repository files, the walkthrough reflects today's code, not last year's documentation.
  • Guided first commits: The skill can walk an engineer through setting up their test database, running the test suite, and submitting their first PR.

Designing an interactive onboarding skill

Here is a complete `.claude/skills/onboard/SKILL.md` skill designed to guide new engineers through an unfamiliar backend repository:

---
name: onboard
description: Use when a new engineer needs an architectural tour, domain concept explanation, or setup assistance in this repository.
---

# Codebase onboarding

When a developer asks to onboard or understand a subsystem:
1. Welcome the developer and ask which subsystem they want to explore: auth, billing, or core pipeline.
2. Provide the 3-minute architectural map: entry routes, business service layer, and database models.
3. Identify the key files for that subsystem and summarize their responsibilities.
4. Walk through the relevant test file to demonstrate how the subsystem is invoked in practice.
5. Offer to run the local test command to verify their development environment.
You type: /onboard billing
Claude announces: Using skill: onboard
Output: Welcome to the billing subsystem tour. Here is how money moves in this repo:
Output: 1. Entry Route: src/routes/billing.ts receives Stripe webhook events.
Output: 2. Processing Service: src/services/subscription.ts validates invoices and updates seat counts.
Output: 3. Data Layer: src/db/models/subscription.prisma records billing cycle timestamps.
Output: To verify your local billing setup, run: npm test tests/billing.test.ts
Note: The skill pointed out the exact request flow and verified the local test command.
Interactive codebase tour session with a new team member.

Encoding company terminology and domain concepts

Every business has acronyms and internal jargon that bewilder new engineers. A medical spa app might have "GPO", "treatment tranches", and "charting locks". An e-commerce app has "SKUs", "backorders", and "drop-ship splits".

Add a domain glossary section to your onboarding skill. When a new hire asks "what is a tranche?", Claude provides the exact business definition and points to the data model where it is implemented.

Guiding the first pull request

The ultimate milestone of onboarding is shipping a first pull request. Pair your onboarding skill with testing commands. Have the skill guide the engineer through writing a unit test, verifying formatting, and staging their commit using the team's conventional commit standards.

You type: run the test suite to verify my local environment
Command: npm test
Output: PASS: 42 test suites passed, 180 tests clean.
Output: Your development environment is verified and ready for feature work.
Running the test suite to verify onboarding setup.
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