Claude Code Ultimate Guide

Learn Claude Code, build reliable agents, and scale their use safely. The website is the primary reading and discovery interface. This repository contains the canonical Markdown sources, reusable files, machine-readable indexes, and contribution history.

Start here: complete a first task online · browse the guide portal · open the complete sitemap · read the Markdown source

Choose your next step

The table below is generated from machine-readable/navigation.json. The same contract feeds the public sitemap, so the repository and website expose the same intent model.

Intent	Browse online
Start	Guide portal · Quick Start · Learning Paths · Quick Reference · AI Roles
Build	Agent Harness Engineering · Loop & Graph Engineering · AI Design Patterns · Context Engineering · Memory Systems · Workflows · Methodologies · MCP or CLI? · Examples
Scale	Security · Enterprise Governance · Observability · Team Metrics · Team Adoption · AI FinOps · LLM Market Snapshot · Subscription Strategy · AI Unit Economics · Team Knowledge · API Gateway
Resources	Resource Hub · Downloads · Cheat Sheets · Ebooks · Diagrams · Ecosystem · Compare · Glossary · FAQ · Guide MCP Server · Related Projects
Updates	Guide Changelog · Claude Code Releases · RSS Feed

Why this guide exists

Claude Code documentation explains the product. This guide connects product behavior to engineering decisions: what belongs in context, when to use an agent instead of a skill, how to verify generated work, and which controls matter when usage moves beyond one developer.

Need	Start with
Understand Claude Code internals	Architecture and Tools Reference
Design agent systems	Agent Harness Engineering, Loop & Graph Engineering and AI Design Patterns
Structure AI-assisted delivery	Methodologies and Workflow Guides
Establish a security boundary	Security Hardening and Sandbox Isolation
Validate understanding	Knowledge Quiz and Recap Cards

The guide favors explicit trade-offs and verifiable procedures. Where evidence is incomplete, the relevant page should preserve that limit instead of presenting one workflow as universal.

Start

Install Claude Code

Anthropic recommends the native installer, which updates itself:

# macOS, Linux, WSL
curl -fsSL https://claude.ai/install.sh | bash

# Windows PowerShell
irm https://claude.ai/install.ps1 | iex

Alternatives that do not auto-update: brew install --cask claude-code, winget install Anthropic.ClaudeCode, or npm install -g @anthropic-ai/claude-code (Node.js 22+). See the official setup page.

Verify the installation and authenticate:

claude --version
claude doctor
claude auth login

The Quick Start chapter documents installation alternatives, authentication, updates, permission modes, and common first-day failures.

Complete a first task

Open a small repository with a clean or understood Git state, then start Claude Code:

cd your-project
claude

Give Claude a bounded request that includes the expected result and verification:

Explain how this project runs its tests. Do not modify files.
Name the relevant commands and cite the files that define them.

Before asking Claude to edit code, add a project-level CLAUDE.md that records the commands and constraints Claude must follow:

This is the beginning of the README. Read the rest at the original. Read the full README ↗