Getting Started with Claude Code

Claude Code is Anthropic's command-line interface for AI-assisted software development. This guide walks you through setup, essential commands, and workflows that make it genuinely useful.

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What Claude Code Does

Claude Code brings AI directly into your terminal. Unlike web-based chat interfaces:

• Context-aware - It understands your entire codebase
• Action-oriented - It can read, write, and execute
• Persistent - Sessions maintain context across tasks
• Integrated - Works with your existing dev tools

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Part 1: Installation

Prerequisites

• Node.js 18+ installed
• An Anthropic API key
• Terminal access (macOS, Linux, or WSL on Windows)

Install via npm

npm install -g @anthropic-ai/claude-code

Authenticate

claude-code auth

This opens a browser window for authentication. Once complete, you're ready.

Verify Installation

claude-code --version

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Part 2: Essential Commands

Start a Session

claude-code

This launches an interactive session in your current directory.

One-Shot Commands

claude-code "explain what this project does"
claude-code "find all TODO comments in the codebase"
claude-code "add error handling to src/api.ts"

Common Flags

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Part 3: Effective Prompting

Be Specific About Files

Read src/components/Button.tsx and explain the props interface

vs.

Explain the Button component

The first is faster because Claude doesn't need to search.

Describe the "Why"

Refactor the authentication flow to use JWTs instead of sessions.
We need this because the app will be deployed to multiple regions.

Context about purpose leads to better decisions.

Break Down Complex Tasks

Instead of:

Build a complete user authentication system

Try:

Let's build auth step by step:
1. First, create the user model in prisma/schema.prisma
2. Then we'll add the auth routes
3. Finally, we'll add middleware

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Part 4: Reading and Understanding Code

Explore a New Codebase

Give me an overview of this project's architecture.
Focus on:
1. Entry points
2. Key abstractions
3. Data flow

Find Patterns

Find all places where we make API calls.
Show me the pattern we use for error handling.

Trace Execution

Trace what happens when a user submits the contact form.
Start from the form component and follow through to the database.

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Part 5: Writing Code

Create New Features

Add a dark mode toggle to the settings page.
Use the existing useTheme hook in lib/hooks.
Match the design system in components/ui.

Fix Bugs

There's a bug where the cart total doesn't update after removing items.
The issue is in components/Cart.tsx.
Find and fix it.

Refactor Safely

Refactor the user service to use the repository pattern.
Keep all existing tests passing.
Don't change the public API.

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Part 6: Working with Tests

Generate Tests

Write unit tests for src/utils/validation.ts.
Cover edge cases for:
- Empty input
- Invalid email formats
- Special characters

Debug Failing Tests

This test is failing:
[paste test output]

Find the bug and fix it.

Run and Verify

claude-code "run the test suite and summarize any failures"

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Part 7: Git Integration

Commit Workflow

Review my staged changes and suggest a commit message.
Follow conventional commit format.

Pull Request Prep

Summarize all changes since main branch.
Write a PR description covering:
- What changed
- Why
- How to test

Code Review

Review the diff for potential issues:
- Security vulnerabilities
- Performance problems
- Style inconsistencies

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Part 8: Project-Specific Context

CLAUDE.md Files

Create a CLAUDE.md file in your project root:

# Project Context

## Architecture
This is a Next.js 14 app with App Router.
Database is PostgreSQL via Prisma.

## Conventions
- Use server components by default
- Keep client components in /components/client
- All API routes go in /app/api

## Important Files
- lib/db.ts - Database client
- lib/auth.ts - Authentication helpers
- types/index.ts - Shared types

Claude Code reads this file automatically.

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Part 9: Slash Commands

Built-in Commands

Custom Commands

Create .claude/commands/ directory for custom commands:

# .claude/commands/review.md

Review the current file for:
1. Security issues
2. Performance optimizations
3. Code style improvements

Suggest fixes with code examples.

Then use: /project:review

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Part 10: Workflows That Work

Morning Standup

What files have I modified since yesterday?
Summarize the changes for a standup update.

End of Day

Review today's changes.
Are there any incomplete features or potential issues?
What should I tackle first tomorrow?

Before Deploying

Run a pre-deployment check:
1. Are there any console.logs left in?
2. Any TODO comments that need addressing?
3. Are all env variables documented?

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Quick Reference

Model Selection

Performance Tips

1. Start specific - Give file paths when you know them
2. Stay focused - One task per conversation for complex work
3. Use context - Create CLAUDE.md for project conventions
4. Verify outputs - Review generated code before committing

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Next Steps

1. Install Claude Code in your most active project
2. Create a CLAUDE.md with project context
3. Try the morning standup workflow for a week
4. Build custom commands for your repetitive tasks

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This guide reflects daily use of Claude Code across multiple production projects. The patterns here are what consistently improve development velocity.