claudebox/README.md

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# claudebox
Run [Claude Code](https://docs.anthropic.com/en/docs/claude-code) inside a [bubblewrap](https://github.com/containers/bubblewrap) sandbox with an allowlisted environment, explicit filesystem mounts, and a minimal PATH.
SSH keys, GPG/age secrets, cloud tokens, and Tailscale state stay completely invisible to the AI agent. If a secret is accessible inside the sandbox, it's a bug.
## Quick start
```bash
nix run git+https://git.toph.so/toph/claudebox
```
Or add to your flake:
```nix
{
inputs.claudebox.url = "git+https://git.toph.so/toph/claudebox";
}
```
Then add `inputs.claudebox.packages.${system}.default` to your `environment.systemPackages` or home-manager packages.
## What it does
- Starts Claude Code inside a bwrap namespace with `--clearenv`
- Only allowlisted env vars enter the sandbox (HOME, PATH, TERM, EDITOR, LANG, ANTHROPIC_API_KEY if set)
- Mounts CWD read-write, Nix store read-only, everything else is tmpfs
- Provides `nix shell` and [comma](https://github.com/nix-community/comma) (`, <tool>`) so Claude can install tools on demand
- Injects a SANDBOX.md so Claude knows it's sandboxed and how to get tools
- Pre-configures git identity and safe.directory from host
## Flags
| Flag | Description |
|------|-------------|
| `--yes`, `-y` | Skip the env audit and launch immediately |
| `--dry-run` | Print the bwrap command without executing |
| `--check` | Verify prerequisites and exit |
| `--shell` | Drop into a bash shell instead of Claude Code |
| `--gc` | Remove stale per-project instance dirs and exit |
| `--` | Pass remaining args to Claude Code |
## Env vars
**Env files (preferred)** — define vars without polluting your shell:
`~/.claudebox/env` — global, loaded on every launch:
```bash
ANTHROPIC_API_KEY=sk-ant-...
MY_GLOBAL_VAR=value
```
`<project>/.claudebox.env` — per-project, loaded when present:
```bash
DATABASE_URL=postgres://localhost/myapp
SOME_PROJECT_VAR=value
```
Add `.claudebox.env` to your `.gitignore` if it contains secrets.
**Pass-through** — inject host vars already set in your shell:
```bash
CLAUDEBOX_EXTRA_ENV=MY_VAR,OTHER_VAR claudebox
```
All injected vars appear in the `[+]` section of the env audit.
## How it works
```
~/.claudebox/ # persistent config dir (host)
├── SANDBOX.md # managed by claudebox, overwritten each launch
├── history.jsonl # conversation history
├── .credentials.json # Claude Code credentials (if present)
└── projects/
└── <16-char-hex>/ # per-project instance dir (keyed by canonical git root)
└── project-root # records the canonical path for this instance
Inside the sandbox:
~/.claude → bind-mounted from host (plugins, skills, hooks, MCP all visible)
~/.claude/projects → bind-mounted from ~/.claudebox/projects/<hash>/ (per-project isolation)
~/.claude/history.jsonl → bind-mounted from ~/.claudebox/history.jsonl
~/.claude/SANDBOX.md → bind-mounted from ~/.claudebox/SANDBOX.md
```
Each project gets an isolated `~/.claude/projects/` directory inside the sandbox, so conversation history and project state are separated per repo. Git worktrees share the same instance dir as their main worktree.
## Requirements
- NixOS or Nix with flakes enabled
- User namespaces (enabled by default on NixOS)
## License
MIT