Claude Code — Leaked Source

The full source code of Anthropic's Claude Code CLI, leaked on March 31, 2026

The original unmodified leaked source is preserved in the backup branch.

How It Leaked
What Is Claude Code?
Documentation
Explore with MCP Server
Directory Structure
Architecture
Key Files
Tech Stack
Design Patterns
GitPretty Setup
Contributing
Disclaimer

How It Leaked

Chaofan Shou (@Fried_rice) discovered that the published npm package for Claude Code included a .map file referencing the full, unobfuscated TypeScript source — downloadable as a zip from Anthropic's R2 storage bucket.

"Claude code source code has been leaked via a map file in their npm registry!"

— @Fried_rice, March 31, 2026

What Is Claude Code?

Claude Code is Anthropic's official CLI tool for interacting with Claude directly from the terminal — editing files, running commands, searching codebases, managing git workflows, and more. This repository contains the leaked src/ directory.


Leaked	2026-03-31
Language	TypeScript (strict)
Runtime	Bun
Terminal UI	React + Ink
Scale	~1,900 files · 512,000+ lines of code

� Documentation

For in-depth guides, see the docs/ directory:

Guide	Description
Architecture	Core pipeline, startup sequence, state management, rendering, data flow
Tools Reference	Complete catalog of all ~40 agent tools with categories and permission model
Commands Reference	All ~85 slash commands organized by category
Subsystems Guide	Deep dives into Bridge, MCP, Permissions, Plugins, Skills, Tasks, Memory, Voice
Exploration Guide	How to navigate the codebase — study paths, grep patterns, key files

Also see: CONTRIBUTING.md · MCP Server README

�🔍 Explore with MCP Server

This repo ships an MCP server that lets any MCP-compatible client (Claude Code, Claude Desktop, VS Code Copilot, Cursor) explore the full source interactively.

Install from npm

The MCP server is published as warrioraashuu-codemaster on npm — no need to clone the repo:

# Claude Code
claude mcp add warrioraashuu-codemaster -- npx -y warrioraashuu-codemaster

One-liner setup (from source)

git clone https://github.com/codeaashu/claude-code.git ~/claude-code \
  && cd ~/claude-code/mcp-server \
  && npm install && npm run build \
  && claude mcp add claude-code-explorer -- node ~/claude-code/mcp-server/dist/index.js

Step-by-step setup

# 1. Clone the repo
git clone https://github.com/codeaashu/claude-code.git
cd claude-code/mcp-server

# 2. Install & build
npm install && npm run build

# 3. Register with Claude Code
claude mcp add claude-code-explorer -- node /absolute/path/to/claude-code/mcp-server/dist/index.js

Replace /absolute/path/to/claude-code with your actual clone path.

VS Code / Cursor / Claude Desktop config

VS Code — add to .vscode/mcp.json:

{
  "servers": {
    "claude-code-explorer": {
      "type": "stdio",
      "command": "node",
      "args": ["${workspaceFolder}/mcp-server/dist/index.js"],
      "env": { "CLAUDE_CODE_SRC_ROOT": "${workspaceFolder}/src" }
    }
  }
}

Claude Desktop — add to your config file:

{
  "mcpServers": {
    "claude-code-explorer": {
      "command": "node",
      "args": ["/absolute/path/to/claude-code/mcp-server/dist/index.js"],
      "env": { "CLAUDE_CODE_SRC_ROOT": "/absolute/path/to/claude-code/src" }
    }
  }
}

Cursor — add to ~/.cursor/mcp.json (same format as Claude Desktop).

Available tools & prompts

Tool	Description
`list_tools`	List all ~40 agent tools with source files
`list_commands`	List all ~50 slash commands with source files
`get_tool_source`	Read full source of any tool (e.g. BashTool, FileEditTool)
`get_command_source`	Read source of any slash command (e.g. review, mcp)
`read_source_file`	Read any file from `src/` by path
`search_source`	Grep across the entire source tree
`list_directory`	Browse `src/` directories
`get_architecture`	High-level architecture overview

Prompt	Description
`explain_tool`	Deep-dive into how a specific tool works
`explain_command`	Understand a slash command's implementation
`architecture_overview`	Guided tour of the full architecture
`how_does_it_work`	Explain any subsystem (permissions, MCP, bridge, etc.)
`compare_tools`	Side-by-side comparison of two tools

Try asking: "How does the BashTool work?" · "Search for where permissions are checked" · "Show me the /review command source"

Custom source path / Remove

# Custom source location
claude mcp add claude-code-explorer -e CLAUDE_CODE_SRC_ROOT=/path/to/src -- node /path/to/mcp-server/dist/index.js

# Remove
claude mcp remove claude-code-explorer

Directory Structure

src/
├── main.tsx                 # Entrypoint — Commander.js CLI parser + React/Ink renderer
├── QueryEngine.ts           # Core LLM API caller (~46K lines)
├── Tool.ts                  # Tool type definitions (~29K lines)
├── commands.ts              # Command registry (~25K lines)
├── tools.ts                 # Tool registry
├── context.ts               # System/user context collection
├── cost-tracker.ts          # Token cost tracking
│
├── tools/                   # Agent tool implementations (~40)
├── commands/                # Slash command implementations (~50)
├── components/              # Ink UI components (~140)
├── services/                # External service integrations
├── hooks/                   # React hooks (incl. permission checks)
├── types/                   # TypeScript type definitions
├── utils/                   # Utility functions
├── screens/                 # Full-screen UIs (Doctor, REPL, Resume)
│
├── bridge/                  # IDE integration (VS Code, JetBrains)
├── coordinator/             # Multi-agent orchestration
├── plugins/                 # Plugin system
├── skills/                  # Skill system
├── server/                  # Server mode
├── remote/                  # Remote sessions
├── memdir/                  # Persistent memory directory
├── tasks/                   # Task management
├── state/                   # State management
│
├── voice/                   # Voice input
├── vim/                     # Vim mode
├── keybindings/             # Keybinding configuration
├── schemas/                 # Config schemas (Zod)
├── migrations/              # Config migrations
├── entrypoints/             # Initialization logic
├── query/                   # Query pipeline
├── ink/                     # Ink renderer wrapper
├── buddy/                   # Companion sprite (Easter egg 🐣)
├── native-ts/               # Native TypeScript utils
├── outputStyles/            # Output styling
└── upstreamproxy/           # Proxy configuration

Architecture

1. Tool System

src/tools/ — Every tool Claude can invoke is a self-contained module with its own input schema, permission model, and execution logic.

Tool	Description
File I/O
`FileReadTool`	Read files (images, PDFs, notebooks)
`FileWriteTool`	Create / overwrite files
`FileEditTool`	Partial modification (string replacement)
`NotebookEditTool`	Jupyter notebook editing
Search
`GlobTool`	File pattern matching
`GrepTool`	ripgrep-based content search
`WebSearchTool`	Web search
`WebFetchTool`	Fetch URL content
Execution
`BashTool`	Shell command execution
`SkillTool`	Skill execution
`MCPTool`	MCP server tool invocation
`LSPTool`	Language Server Protocol integration
Agents & Teams
`AgentTool`	Sub-agent spawning
`SendMessageTool`	Inter-agent messaging
`TeamCreateTool` / `TeamDeleteTool`	Team management
`TaskCreateTool` / `TaskUpdateTool`	Task management
Mode & State
`EnterPlanModeTool` / `ExitPlanModeTool`	Plan mode toggle
`EnterWorktreeTool` / `ExitWorktreeTool`	Git worktree isolation
`ToolSearchTool`	Deferred tool discovery
`SleepTool`	Proactive mode wait
`CronCreateTool`	Scheduled triggers
`RemoteTriggerTool`	Remote trigger
`SyntheticOutputTool`	Structured output generation

2. Command System

src/commands/ — User-facing slash commands invoked with / in the REPL.

Command	Description	Command	Description
`/commit`	Git commit	`/memory`	Persistent memory
`/review`	Code review	`/skills`	Skill management
`/compact`	Context compression	`/tasks`	Task management
`/mcp`	MCP server management	`/vim`	Vim mode toggle
`/config`	Settings	`/diff`	View changes
`/doctor`	Environment diagnostics	`/cost`	Check usage cost
`/login` / `/logout`	Auth	`/theme`	Change theme
`/context`	Context visualization	`/share`	Share session
`/pr_comments`	PR comments	`/resume`	Restore session
`/desktop`	Desktop handoff	`/mobile`	Mobile handoff

3. Service Layer

src/services/ — External integrations and core infrastructure.

Service	Description
`api/`	Anthropic API client, file API, bootstrap
`mcp/`	Model Context Protocol connection & management
`oauth/`	OAuth 2.0 authentication
`lsp/`	Language Server Protocol manager
`analytics/`	GrowthBook feature flags & analytics
`plugins/`	Plugin loader
`compact/`	Conversation context compression
`extractMemories/`	Automatic memory extraction
`teamMemorySync/`	Team memory synchronization
`tokenEstimation.ts`	Token count estimation
`policyLimits/`	Organization policy limits
`remoteManagedSettings/`	Remote managed settings

4. Bridge System

src/bridge/ — Bidirectional communication layer connecting IDE extensions (VS Code, JetBrains) with the CLI.

Key files: bridgeMain.ts (main loop) · bridgeMessaging.ts (protocol) · bridgePermissionCallbacks.ts (permission callbacks) · replBridge.ts (REPL session) · jwtUtils.ts (JWT auth) · sessionRunner.ts (session execution)

5. Permission System

src/hooks/toolPermission/ — Checks permissions on every tool invocation.

Prompts the user for approval/denial or auto-resolves based on the configured permission mode: default, plan, bypassPermissions, auto, etc.

6. Feature Flags

Dead code elimination at build time via Bun's bun:bundle:

import { feature } from 'bun:bundle'

const voiceCommand = feature('VOICE_MODE')
  ? require('./commands/voice/index.js').default
  : null

Notable flags: PROACTIVE · KAIROS · BRIDGE_MODE · DAEMON · VOICE_MODE · AGENT_TRIGGERS · MONITOR_TOOL

Key Files

File	Lines	Purpose
`QueryEngine.ts`	~46K	Core LLM API engine — streaming, tool loops, thinking mode, retries, token counting
`Tool.ts`	~29K	Base types/interfaces for all tools — input schemas, permissions, progress state
`commands.ts`	~25K	Command registration & execution with conditional per-environment imports
`main.tsx`	—	CLI parser + React/Ink renderer; parallelizes MDM, keychain, and GrowthBook on startup

Tech Stack

Category	Technology
Runtime	Bun
Language	TypeScript (strict)
Terminal UI	React + Ink
CLI Parsing	Commander.js (extra-typings)
Schema Validation	Zod v4
Code Search	ripgrep (via GrepTool)
Protocols	MCP SDK · LSP
API	Anthropic SDK
Telemetry	OpenTelemetry + gRPC
Feature Flags	GrowthBook
Auth	OAuth 2.0 · JWT · macOS Keychain

Design Patterns

Parallel Prefetch — Startup optimization

MDM settings, keychain reads, and API preconnect fire in parallel as side-effects before heavy module evaluation:

// main.tsx
startMdmRawRead()
startKeychainPrefetch()

Lazy Loading — Deferred heavy modules

OpenTelemetry (~400KB) and gRPC (~700KB) are loaded via dynamic import() only when needed.

Agent Swarms — Multi-agent orchestration

Sub-agents spawn via AgentTool, with coordinator/ handling orchestration. TeamCreateTool enables team-level parallel work.

Skill System — Reusable workflows

Defined in skills/ and executed through SkillTool. Users can add custom skills.

Plugin Architecture — Extensibility

Built-in and third-party plugins loaded through the plugins/ subsystem.

GitPretty Setup

Show per-file emoji commit messages in GitHub's file UI

# Apply emoji commits
bash ./gitpretty-apply.sh .

# Optional: install hooks for future commits
bash ./gitpretty-apply.sh . --hooks

# Push as usual
git push origin main

Contributing

Contributions to documentation, the MCP server, and exploration tooling are welcome. See CONTRIBUTING.md for guidelines.

Note: The src/ directory is the original leaked source and should not be modified.

Disclaimer

This repository archives source code leaked from Anthropic's npm registry on 2026-03-31. All original source code is the property of Anthropic. This is not an official release and is not licensed for redistribution. Contact aashuu ✦ for any comments.

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Claude Code — Leaked Source

Table of Contents

How It Leaked

What Is Claude Code?

� Documentation

�🔍 Explore with MCP Server

Install from npm

One-liner setup (from source)

Available tools & prompts

Custom source path / Remove

Directory Structure

Architecture

1. Tool System

2. Command System

3. Service Layer

4. Bridge System

5. Permission System

6. Feature Flags

Key Files

Tech Stack

Design Patterns

GitPretty Setup

Contributing

Disclaimer

Uh oh!

FilesExpand file tree

README.md

Latest commit

History

README.md

File metadata and controls

Claude Code — Leaked Source

Table of Contents

How It Leaked

What Is Claude Code?

� Documentation

�🔍 Explore with MCP Server

Install from npm

One-liner setup (from source)

Available tools & prompts

Custom source path / Remove

Directory Structure

Architecture

1. Tool System

2. Command System

3. Service Layer

4. Bridge System

5. Permission System

6. Feature Flags

Key Files

Tech Stack

Design Patterns

GitPretty Setup

Contributing

Disclaimer