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.

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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
.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
node_modules/bundle/	Runtime polyfill for bun:bundle feature flag system

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Quick Start

Prerequisites

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

Install & Build

git clone https://github.com/beita6969/claude-code.git
cd claude-code
# Install dependencies
bun install
# Build (produces dist/main.js, ~20MB)
bun build src/main.tsx --outdir=dist --target=bun

Run

# 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:

unset ANTHROPIC_API_KEY

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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:bundlefeature() function controls feature gating. In this build, all features default to disabled. To enable features, edit node_modules/bundle/index.js:

constENABLED_FEATURES=newSet([// 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.