Claude Code Source - Buildable Research Fork

A buildable, modifiable, and runnable version of the Claude Code source.

Based on the Claude Code source snapshot publicly exposed on 2026-03-31 via an npm source map leak. The original snapshot contained only raw TypeScript source with no build configuration — it could not be compiled or run. This fork reconstructs the full build system and fixes all missing components to make it functional.

Quick Start | Architecture | Feature Flags | Extension Guide

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Quick Start

Prerequisites

• Bun >= 1.3.x
• Valid Anthropic authentication (OAuth via claude login or ANTHROPIC_API_KEY)

Install & Run

git clone https://github.com/beita6969/claude-code.git
cd claude-code

# Install dependencies (auto-creates bun:bundle polyfill via postinstall)
bun install

# Run directly
bun src/main.tsx -p "your prompt here" --output-format text

Build (Optional)

# Compile to single bundle (~20MB)
bun build src/main.tsx --outdir=dist --target=bun

Run Modes

# Headless print mode (no TTY needed)
bun src/main.tsx -p "your prompt here" --output-format text

# JSON output
bun src/main.tsx -p "your prompt here" --output-format json

# Interactive REPL mode (needs TTY)
bun src/main.tsx

Note: If ANTHROPIC_API_KEY is set in your environment, it must be valid. To use OAuth instead, unset it: bash unset ANTHROPIC_API_KEY

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What Changed vs. the Original Snapshot

The original snapshot shipped no package.json, no tsconfig.json, no lockfile, and no build scripts. Over 100 internal/feature-gated modules were also missing from the source map.

Build System (Reconstructed)

File	Purpose
package.json	60+ npm dependencies reverse-engineered from ~1,900 source files
tsconfig.json	TypeScript config (ESNext + JSX + Bun bundler resolution)
bunfig.toml	Bun runtime configuration
scripts/postinstall.sh	Auto-creates bun:bundle runtime polyfill after bun install
.gitignore	Excludes node_modules/, dist/, lockfiles

Stub Modules (Created)

The original source imports many Anthropic-internal packages and feature-gated modules that were not included in the leak. Minimal stubs were created so the build completes:

Category	Count	Examples
Anthropic internal packages (@ant/*)	4	computer-use-mcp, computer-use-swift, claude-for-chrome-mcp
Native addons	3	color-diff-napi, audio-capture-napi, modifiers-napi
Cloud provider SDKs	6	Bedrock/Foundry/Vertex SDK, AWS STS, Azure Identity
OpenTelemetry exporters	10	OTLP gRPC/HTTP/Proto exporters
Other optional packages	2	sharp, turndown
Feature-gated source modules	~90	Tools, commands, services, components excluded from the source map

Source Fixes

File	Change
src/main.tsx	Runtime MACRO constant injection (compile-time define in production)
src/main.tsx	Fixed Commander.js -d2e short flag incompatibility
src/bootstrap/state.ts	Added missing isReplBridgeActive() export
src/types/connectorText.ts	Added isConnectorTextBlock function stub
src/tools/WorkflowTool/constants.ts	Added WORKFLOW_TOOL_NAME export

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Architecture Overview

src/
├── main.tsx              # CLI entrypoint (Commander.js + React/Ink)
├── QueryEngine.ts        # Core LLM API engine
├── query.ts              # Agentic loop (async generator)
├── Tool.ts               # Tool type definitions
├── tools.ts              # Tool registry
├── commands.ts           # Command registry
├── context.ts            # System prompt context
│
├── tools/                # 40+ tool implementations
│   ├── AgentTool/        # Sub-agent spawning & coordination
│   ├── BashTool/         # Shell command execution
│   ├── FileReadTool/     # File reading
│   ├── FileEditTool/     # File editing
│   ├── GrepTool/         # ripgrep-based search
│   ├── MCPTool/          # MCP server tool invocation
│   ├── SkillTool/        # Skill execution
│   └── ...
│
├── services/             # External integrations
│   ├── api/              # Anthropic API client
│   ├── mcp/              # MCP server management
│   └── ...
│
├── memdir/               # Persistent memory system
├── skills/               # Skill system (bundled + user)
├── components/           # React/Ink terminal UI
├── hooks/                # React hooks
├── coordinator/          # Multi-agent orchestration
└── stubs/                # Stub packages for missing internals

Key Systems

System	Files	Description
Agentic Loop	query.ts, QueryEngine.ts	while(true) async generator: query -> tool calls -> results -> loop
Memory	memdir/	4-type file-based memory (user/feedback/project/reference) with MEMORY.md index
MCP	services/mcp/	Model Context Protocol server management (stdio/http/sse/ws)
Skills	skills/, tools/SkillTool/	Reusable workflow templates (SKILL.md format)
Agents	tools/AgentTool/	Custom agent types via .claude/agents/*.md
System Prompt	constants/prompts.ts	Layered prompt: static -> dynamic -> memory -> agent

Extension Points (No Source Modification Needed)

Mechanism	Location	Format
Custom Skills	.claude/skills/name/SKILL.md	YAML frontmatter + Markdown
Custom Agents	.claude/agents/name.md	YAML frontmatter + Markdown
MCP Servers	.mcp.json	JSON config
Hooks	~/.claude/settings.json	JSON event-action mappings

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Feature Flags

The bun:bundle feature() function controls feature gating. In this build, all features default to disabled. To enable features, edit node_modules/bundle/index.js (auto-generated by bun install):

const ENABLED_FEATURES = new Set([
  // Uncomment to enable:
  // 'KAIROS',              // Assistant mode
  // 'PROACTIVE',           // Proactive mode
  // 'BRIDGE_MODE',         // IDE bridge
  // 'VOICE_MODE',          // Voice input
  // 'COORDINATOR_MODE',    // Multi-agent coordinator
  // 'EXTRACT_MEMORIES',    // Background memory extraction
  // 'TEAMMEM',             // Team memory
])

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Tech Stack

Layer	Technology
Runtime	Bun
Language	TypeScript (strict)
Terminal UI	React + Ink
CLI	Commander.js
Validation	Zod v4
Search	ripgrep
Protocols	MCP SDK, LSP
API	Anthropic SDK
Telemetry	OpenTelemetry

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Scale

• ~1,900 source files
• 512,000+ lines of TypeScript
• 40+ tools, 100+ commands, 140+ UI components
• 20MB compiled bundle

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Disclaimer

• This repository is for educational and research purposes only.
• The original Claude Code source is the property of Anthropic.
• This repository is not affiliated with, endorsed by, or maintained by Anthropic.
• Original source exposure: 2026-03-31 via npm source map leak.

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