Plan Stack

What this lesson teaches

Plan Stack is a methodology for AI-assisted development: create a plan first, implement second, review always. This structure prevents wasted effort and improves code quality.

The Core Cycle

1. Plan — Write down what you'll build before touching code
2. Implement — Execute the plan with Claude's help
3. Review — Check the result against the plan

This isn't bureaucracy—it's how you avoid redoing work and catch mistakes early.

Writing a Plan

Create a plan file (e.g., docs/plans/20240115_add_auth.md) before starting:

# Add User Authentication

## Goal
Users can log in with email/password and stay logged in.

## Approach
- Use JWT tokens stored in httpOnly cookies
- Add /api/auth/login and /api/auth/logout endpoints
- Create auth middleware for protected routes

## Files to Change
- src/api/auth.ts (new)
- src/middleware/auth.ts (new)
- src/api/user.ts (modify)

## Success Criteria
- Login returns token on valid credentials
- Protected routes reject requests without valid token
- Tests pass

Using Plans with Claude

Share your plan at the start of a session:

> I'm implementing user auth. Here's my plan:
> [paste plan]
> Let's start with the login endpoint.

Claude now knows the full scope and can make consistent decisions across files.

Including Plans in Commits

Link your commits to plans:

git commit -m "Add login endpoint

Implements: docs/plans/20240115_add_auth.md (step 1)"

This creates a traceable history of decisions and implementations.