CLAUDE.md Mastery

What is CLAUDE.md and why it matters

Drop a single CLAUDE.md file in the root of any project. Claude Code reads it automatically at the start of every session.

It becomes your team’s shared “memory” and rulebook: past mistakes, coding conventions, architecture decisions, and best practices. No more repeating yourself. Every bug fix becomes permanent knowledge.

Result: Claude stops acting like a fresh chatbot and starts behaving like a senior engineer who already knows your codebase inside out.

Quick Start for Your Team

1. Create CLAUDE.md at the root of your repo
2. Copy the template below and customize it
3. Run claude in your terminal — it loads automatically
4. After every session, update the file (or tasks/lessons.md) with new rules
5. Commit it like any other code — it’s living documentation

Pro tip: Start a new project with claude init and Claude will help generate a starter CLAUDE.md for you.

The Official Anthropic-Inspired Template

Here’s the exact template shared by Boris Cherny (Claude Code creator) that his team uses daily at Anthropic. Copy-paste and adapt:

# CLAUDE.md

## Plan Mode Default
- Enter plan mode for any non-trivial task (3+ steps or architectural decisions)
- If something goes wrong, STOP and re-plan immediately — don’t keep pushing
- Use plan mode for verification steps, not just building
- Write detailed specs upfront to reduce ambiguity

## Subagent Strategy
- Use subagents frequently to keep the main context window clean
- Offload research, exploration, and parallel analysis to subagents
- For complex problems, throw more compute via subagents
- Assign one task per subagent for focused execution

## Self-Improvement Loop
- After any correction from the user, update tasks/lessons.md with the pattern
- Write rules for yourself to prevent repeating the same mistake
- Ruthlessly iterate on these lessons until the mistake rate drops
- Review lessons at the start of each session

## Verification Before Done
- Never mark a task complete without proving it works
- Diff behavior between main and your changes when relevant
- Ask yourself: “Would a staff engineer approve this?”
- Run tests, check logs, and demonstrate correctness

## Demand Elegance (Balanced)
- For non-trivial changes, ask: “Is there a more elegant solution?”
- If a fix feels hacky, ask: “Knowing everything I know now, implement the elegant solution.”
- Skip this for simple fixes — don’t over-engineer
- Challenge your own work before presenting it

## Autonomous Bug Fixing
- When given a bug report: just fix it
- Use logs, errors, and failing tests to diagnose
- Require zero context switching from the user
- Fix failing CI tests automatically

## Task Management
1. Plan First – Write the plan in tasks/todo.md with checkable items
2. Verify Plan – Confirm the plan before implementation
3. Track Progress – Mark items complete as you go
4. Explain Changes – Provide a high-level summary at each step
5. Document Results – Add a review section to tasks/todo.md
6. Capture Lessons – Update tasks/lessons.md after corrections

## Core Principles
- Simplicity First: Make every change as simple as possible and minimize code impact.
- No Laziness: Find root causes. Avoid temporary fixes. Maintain senior-level engineering standards.

5 Extra Tips That Make CLAUDE.md 10× More Powerful

Team Workflow Recommendation

1. Everyone works in the same repo
2. CLAUDE.md is the single source of truth for “how we code here”
3. After a PR review or bug, the author adds the lesson to lessons.md
4. Review CLAUDE.md together every sprint

This is how you turn Claude from a helpful tool into a true team member that gets smarter every day.

Ready to level up your team?

Save this page, create your first CLAUDE.md today, and watch your Claude Code sessions become dramatically more consistent and efficient.

Questions? Drop them in our team chat — let’s iterate on this together.