Claude Code Best V5 (CCB)

Which Claude do you like? The open source one is the best.

A reverse-engineered / decompiled source restoration of Anthropic's official Claude Code CLI tool. The goal is to reproduce most of Claude Code's functionality and engineering capabilities. It's abbreviated as CCB.

Documentation (Chinese) — PR contributions welcome.

Sponsor placeholder.

• v1: Basic runability and type checking pass
• V2: Complete engineering infrastructure
  • Biome formatting may not be implemented first to avoid code conflicts
  • Build pipeline complete, output runnable on both Node.js and Bun
• V3: Extensive documentation and documentation site improvements
• V4: Large-scale test suite for improved stability
  • Buddy pet feature restored Docs
  • Auto Mode restored Docs
  • All features now configurable via environment variables instead of bun --feature
• V5: Enterprise-grade monitoring/reporting, missing tools补全, restrictions removed
  • Removed anti-distillation code
  • Web search capability (using Bing) Docs
  • Debug mode support Docs
  • Disabled auto-updates
  • Custom Sentry error reporting support Docs
  • Custom GrowthBook support (GB is open source — configure your own feature flag platform) Docs
  • Custom login mode — configure Claude models your way
• V6: Large-scale refactoring, full modular packaging
  • V6 will be a new branch; main branch will be archived as a historical version

I don't know how long this project will survive. Star + Fork + git clone + .zip is the safest bet.

This project updates rapidly — Opus continuously optimizes in the background, with new changes almost every few hours.

Claude has burned over $1000, out of budget, switching to GLM to continue; @zai-org GLM 5.1 is quite capable.

Quick Start

Prerequisites

Make sure you're on the latest version of Bun, otherwise you'll run into all sorts of weird bugs. Run bun upgrade!

• Bun >= 1.3.11

Install Bun:

# Linux and macOS
curl -fsSL https://bun.sh/install | bash

# Windows (PowerShell)
powershell -c "irm bun.sh/install.ps1 | iex"

Post-installation steps:

1. Make bun available in the current terminal

   The installer adds ~/.bun/bin to the matching shell configuration file. On macOS with the default zsh shell, you may see:

   Added "~/.bun/bin" to $PATH in "~/.zshrc"
   

   Restart the current shell as the installer suggests:

   exec /bin/zsh
   

   If you use bash, reload the bash configuration:

   source ~/.bashrc
   

   Windows PowerShell users can close and reopen PowerShell.

2. Verify that Bun is available:

   bun --help
   bun --version
   

3. Update to latest version (if already installed):

   bun upgrade
   

• Standard Claude Code configuration — each provider has its own setup method

Command Execution Location

• Bun installation and checking commands can be run from any directory: curl -fsSL https://bun.sh/install | bash, bun --help, bun --version, bun upgrade
• Project dependency installation, development mode, and builds must be run from this repository root, the directory containing package.json.

Install

cd /path/to/claude-code
bun install

Run

# Dev mode — if you see version 888, it's working
bun run dev

# Build
bun run build

The build uses code splitting (build.ts), outputting to dist/ (entry dist/cli.js + ~450 chunk files).

The build output runs on both Bun and Node.js — you can publish to a private registry and run directly.

If you encounter a bug, please open an issue — we'll prioritize it.

First-time Setup /login

After the first run, enter /login in the REPL to access the login configuration screen. Select Anthropic Compatible to connect to third-party API-compatible services (no Anthropic account required).

Fields to fill in:

Field	Description	Example
Base URL	API service URL	https://api.example.com/v1
API Key	Authentication key	sk-xxx
Haiku Model	Fast model ID	claude-haiku-4-5-20251001
Sonnet Model	Balanced model ID	claude-sonnet-4-6
Opus Model	High-performance model ID	claude-opus-4-6

• Tab / Shift+Tab to switch fields, Enter to confirm and move to the next, press Enter on the last field to save
• Model fields auto-fill from current environment variables
• Configuration saves to ~/.claude/settings.json under the env key, effective immediately

You can also edit ~/.claude/settings.json directly:

{
  "env": {
    "ANTHROPIC_BASE_URL": "https://api.example.com/v1",
    "ANTHROPIC_AUTH_TOKEN": "sk-xxx",
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "claude-haiku-4-5-20251001",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "claude-sonnet-4-6",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "claude-opus-4-6"
  }
}

Supports all Anthropic API-compatible services (e.g., OpenRouter, AWS Bedrock proxies, etc.) as long as the interface is compatible with the Messages API.

Feature Flags

All feature toggles are enabled via FEATURE_<FLAG_NAME>=1 environment variables, for example:

FEATURE_BUDDY=1 FEATURE_FORK_SUBAGENT=1 bun run dev

See docs/features/ for detailed descriptions of each feature. Contributions welcome.

VS Code Debugging

The TUI (REPL) mode requires a real terminal and cannot be launched directly via VS Code's launch config. Use attach mode:

Steps

1. Start inspect server in terminal:

   bun run dev:inspect
   

   This outputs an address like ws://localhost:8888/xxxxxxxx.

2. Attach debugger from VS Code:

   • Set breakpoints in src/ files
   • Press F5 → select "Attach to Bun (TUI debug)"

Documentation & Links

• Online docs (Mintlify): ccb.agent-aura.top — source in docs/, PR contributions welcome
• DeepWiki: https://deepwiki.com/claude-code-best/claude-code

Contributors

Star History

License

This project is for educational and research purposes only. All rights to Claude Code belong to Anthropic.