Module 03: Memory & Config

Module 03: Memory & Config

Time: 1 hour | Complexity: ⭐⭐ Intermediate

Goal

Configure Claude Code to remember your preferences and project-specific rules. Build your first CLAUDE.md file.

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What You’ll Learn

• How Claude Code’s memory hierarchy works
• Creating and structuring CLAUDE.md files
• Settings and their precedence
• Custom instructions and agent definitions
• Project vs global configuration

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The Memory Hierarchy

Claude Code remembers preferences at three levels:

┌──────────────────────────────────────────┐
│ 1. GLOBAL (~/.claude/CLAUDE.md)          │
│    Applies to ALL your projects          │
│    Example: Your coding style, timezone  │
└──────────────────────────────────────────┘
                    ▲
                    │ (overridden by)
                    │
┌──────────────────────────────────────────┐
│ 2. PROJECT (/your-project/CLAUDE.md)    │
│    Applies to THIS project only          │
│    Example: Team standards, tech stack   │
└──────────────────────────────────────────┘
                    ▲
                    │ (overridden by)
                    │
┌──────────────────────────────────────────┐
│ 3. PERSONAL (/your-project/.claude/)    │
│    Local settings, not committed to git  │
│    Example: API keys, personal prefs     │
└──────────────────────────────────────────┘

Rule

Settings at level 3 override level 2, which overrides level 1.

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Creating Your First CLAUDE.md

CLAUDE.md is a simple markdown file that tells Claude Code your rules.

Basic Structure

# My Project

## Purpose
Brief description of what this project does.

## Tech Stack
- TypeScript
- React 18
- Next.js
- PostgreSQL

## Coding Standards
- Use functional components only
- All exports must be typed
- Max 300 lines per file
- Use meaningful variable names (no `x`, `temp`)

## Behavioral Rules
Always review diffs before accepting.
Use /plan for any breaking changes.

## Git Workflow
- All work on feature branches
- PRs require 1 approval
- Commits must be squashed

## Current Status
What you're currently working on.

Minimal Example (Start Here)

Create /your-project/CLAUDE.md:

# My Project

## Quick Context
- Frontend: React with TypeScript
- Backend: Node.js with Express
- Database: PostgreSQL
- Package manager: pnpm

## Coding Rules
- Functional programming preferred
- All functions must have type signatures
- Tests are required for features
- No console.log in production code

## My Preferences
- Use /plan for architectural changes
- Be verbose in comments, not code
- Ask before making cross-file refactors

Claude will automatically read this file at session start and follow your rules.

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What Can Go in CLAUDE.md?

You can configure almost anything. Common sections:

1. Project Overview

## Purpose
This is our payment processing backend.
It handles credit card validation and transaction logging.

## Important
- Handles PCI-DSS compliance critical code
- Must never log card numbers
- All changes need security review

2. Tech Stack

## Stack
- Language: Python 3.10+
- Framework: Django 4.0
- Database: PostgreSQL 13
- Cache: Redis
- Task queue: Celery

3. Coding Standards

## Code Style
- Follow PEP 8
- Type hints on all functions
- Docstrings in Google format
- No wildcard imports
- Max line length: 100 chars

## Testing
- Minimum 80% coverage
- Unit + integration tests
- Use pytest

4. Rules

## Rules
- All PRs require review
- No direct pushes to main
- Database migrations need approval
- Security changes flagged automatically
- /plan mode for refactors >100 lines

5. Current Work

## Current Task
Building the checkout flow.
Working on: src/checkout/payment-form.tsx
Dependencies: stripe-js library, payment API

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Global CLAUDE.md

For settings that apply to all your projects, create ~/.claude/CLAUDE.md:

# My Global Preferences

## Communication Style
- Be direct and factual
- Show working in steps
- Suggest alternatives when unclear

## Tools I Use
- TypeScript for all JS projects
- Python for data/scripts
- Docker for deployment
- Git for all version control

## My Timezone
America/New_York

## Work Hours
Mon-Fri 9am-5pm (UTC-5)

Claude will load this at startup and combine it with your project CLAUDE.md.

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Project-Specific vs Global

Use Global for:

• Your general coding style (naming conventions, approach)
• Tools you always use
• Communication preferences
• General principles

Use Project for:

• Team standards (if different from your global)
• Project-specific tech stack
• Business rules (PCI compliance, etc)
• Current work context

Example

Global (~/.claude/CLAUDE.md):

## My Style
Functional programming, clear variable names, typed functions

Project (my-payment-app/CLAUDE.md):

## Special Rules
Security critical—use /plan for all changes.
Must handle PCI compliance.

Claude combines both: your style + project rules.

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Exercise: Create Your CLAUDE.md

Step 1: Choose a Project

Use an existing project or create a test directory:

mkdir test-claude-config
cd test-claude-config
git init

Step 2: Create CLAUDE.md

cat > CLAUDE.md << 'EOF'
# My Test Project

## Tech Stack
- Language: [your main language]
- Framework: [what you use]
- Database: [if applicable]

## Coding Standards
- [Rule 1]
- [Rule 2]

## My Preferences
- [Preference 1]
- [Preference 2]
EOF

Step 3: Start Claude

claude

Claude will show that it loaded CLAUDE.md at startup.

Step 4: Test It

Ask Claude to do something. It should follow your rules.

Add a function called greet that returns "Hello, World!"

Claude should:

1. Mention your tech stack
2. Follow your coding standards
3. Respect your preferences

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.claude/ Directory

For local settings (not committed), use .claude/:

my-project/
├── CLAUDE.md           (committed - team rules)
├── .claude/
│   ├── settings.json   (not committed - personal settings)
│   ├── agents/         (custom agents)
│   ├── skills/         (custom skills)
│   └── hooks/          (automation scripts)

Add to .gitignore:

.claude/
.claude/settings.json

Exception: You can commit .claude/agents/ if they’re team-wide.

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Settings.json (Optional)

For fine-grained control, create .claude/settings.json:

{
  "model": "claude-opus-4-7",
  "temperature": 0.7,
  "context_threshold": 0.75,
  "auto_compact": true,
  "require_diff_review": true,
  "max_file_size": 10000
}

Common settings:

• model: Which Claude model to use
• context_threshold: When to warn about context (0.7 = 70%)
• auto_compact: Automatically compact when threshold reached
• require_diff_review: Force review of all changes (safe default)

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Agents & Skills (Preview)

In CLAUDE.md, you can reference custom agents:

## Available Agents
- /code-reviewer: Reviews code for quality
- /security-auditor: Scans for vulnerabilities
- /test-writer: Generates test cases

Use with: /agent code-reviewer

These are defined in .claude/agents/ (covered in Module 04).

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Best Practices

DO

✅ Keep CLAUDE.md updated as your project evolves

✅ Version control your project CLAUDE.md (helps teammates)

✅ Be specific about requirements (not vague)

✅ Include “Current Status” section so Claude has context

✅ Document important business rules

DON’T

❌ Store passwords or secrets in CLAUDE.md (use .env or secrets manager)

❌ Make it too long (>500 lines is overwhelming)

❌ Use conflicting rules between global and project

❌ Assume Claude will remember previous sessions’ preferences

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Validation: You’re Ready If…

✓ You’ve created a CLAUDE.md file in a project

✓ You can explain the three-level hierarchy (global, project, personal)

✓ You understand what should go in committed CLAUDE.md vs .claude/

✓ You’ve started Claude and seen it load your CLAUDE.md

✓ Claude followed at least one rule from your CLAUDE.md

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What’s Next?

Module 04: Agents & Specialization covers:

• Creating specialized agents for specific tasks
• Restricting agent capabilities
• Orchestrating multiple agents
• Team workflows with agents

This teaches you how to create focused AI personas instead of using one general Claude.

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Completed Module 03? → Ready for Module 04: Agents & Specialization