brig README

The project's README from github.com/brig-sh/brig. As one markdown file: README.md.

brig

Release CI Coverage Go License: Apache 2.0

Brig runs a coding agent inside a microVM on your own machine.

An agent working unattended can only damage what you handed it. Point it at one project, and a bad edit or a bad command reaches no further than that project. When you are done, throw the sandbox away and start clean.

How it works

One command starts a sandbox and runs the agent in it:

brig run claude ~/code/demo

A session is <agent> or <agent>@<label>, the ref every command takes. claude and claude@refactor are two independent sessions of the same agent, each with its own sandbox. The guest home is the host directory holding a session's settings and history. claude resolves to the claude-code agent, so its guest home is ~/brig/claude-code, and claude@refactor's is the sibling ~/brig/claude-code-refactor, not a directory inside it.

Name a project on the run line, and Brig mounts it read-write at /work/<name>, where the agent starts. Credentials reach the guest only when you deliver them: the sandbox boots with none, and the agent asks you to log in. What the guest does not get: every other host directory, your keychain, and your SSH agent. docs/sessions.md is the full model.

Requirements

Host Supported
Mac, Apple silicon, macOS 15 or newer Yes
Mac, Apple silicon, macOS 14 Yes, with BRIG_HYPERVISOR=vz
Intel Mac No
Linux, x86-64 or arm64 Yes, with nerdctl, containerd and the urunc shim

macOS 15 is the floor: six of the eight built-in profiles need the hvi backend. See docs/install.md#platform-support for the rest.

Install

brew tap brig-sh/brig
brew trust brig-sh/brig
brew install --cask brig

The cask brings hull and cosign with it. For install.sh, Linux, or a source build, see docs/install.md.

First run

brig doctor

Each line is a check. A !! line prints its fix beside it.

mkdir -p ~/code/demo
brig run claude ~/code/demo

Brig prints brig: image and boot assets verified, Claude Code asks you to log in inside the sandbox, and pwd inside the agent prints /work/demo. The first run pulls the guest image and the boot assets, so it is slow. docs/authentication.md covers the login and how to carry one in from the host.

brig stop claude    # stop the sandbox, keep its name
brig rm claude      # stop it and remove it

Neither touches ~/brig/claude-code or ~/code/demo. docs/quickstart.md walks through all of this, explained.

The boundary

brig sandbox architecture. brig run resolves the session on the host. hull drives a microVM on macOS, urunc over KVM on Linux. Both give the guest the same contract: a guest home, a project mount, per-exec credentials, and an image whose signature brig checks

The project mount is read-write, and those are your real files: the agent can change anything under it. On the default shared network the agent reaches the internet, so anything it can read it can also send. Brig enforces egress policy only on hull's hvi backend, and refuses a policy-bound run on any other backend rather than run it unenforced. Image verification defaults to warn, which reports an unverifiable image and boots it anyway. Set BRIG_VERIFY=require to refuse one instead. docs/security.md has the full picture.

Documentation

If you want to Read
Install Brig on any supported host docs/install.md
Get a first agent running, step by step docs/quickstart.md
Understand homes, projects and sessions docs/sessions.md
Log an agent in, or give it Git access docs/authentication.md, docs/secrets.md
Look up a command, a flag or a variable docs/cli.md
Run your own agent or your own image docs/profiles.md, docs/guest-image.md
Restrict what the guest can reach docs/policies.md
Understand the isolation, and its limits docs/security.md
Know what Brig counts, and turn it off docs/telemetry.md
Fix something that went wrong docs/troubleshooting.md
Move off a retired command spelling docs/migration.md
Know what is stable and what is not docs/stability.md

The full index is docs/README.md.

Project status

Brig is a prerelease, in the 0.1.0-rc series. brig version prints yours, and docs/stability.md says what you can script against today. docs/support.md says where to ask a question or file a bug, and SECURITY.md is where to report a vulnerability instead of a public issue. CONTRIBUTING.md covers the build, the tests and the review norms, and AI_POLICY.md says how AI-assisted contributions are handled. Brig ships under the Apache License 2.0. See LICENSE.

Brig itself counts nothing. On macOS the hull runtime it drives counts a few events, and on Linux nothing is sent. brig telemetry status shows the current setting, and brig telemetry off turns it off. docs/telemetry.md has the field-by-field detail.

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brig (brig-sh/brig)

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231 ·GitHub
Brig
What is this?Brig is a Go CLI (brig) with a session daemon (brigd) that runs coding agents inside a microVM sandbox on your own machine, so an unattended agent can only damage the one project you hand it.
So what am I actually running — a CLI, a service, a VM?Both a CLI and a daemon: one command starts a microVM sandbox and runs the agent in it, and every command works on a session ref like claude or claude@refactor.
How do I install it, and what does the first run look like?Install the Homebrew cask — it brings the hull runtime and cosign with it; install.sh, Linux and source builds are covered in docs/install.md. The first run pulls the guest image and boot assets, so it is slow.
Will it run on my machine, or does it need special hardware?Apple Silicon Macs on macOS 15 or newer; macOS 14 works with BRIGHYPERVISOR=vz, and Intel Macs are not supported. Linux on x86-64 or arm64 also works, but needs nerdctl, containerd and the urunc shim.
How locked down is the agent, really?The project directory is mounted read-write and holds your real files, so the agent can change anything under it. On the default shared network it also reaches the internet — anything it can read, it can send out.
Can the agent peek at my other files, passwords or SSH keys?No: the sandbox boots with no credentials, and you deliver them only when the agent asks you to log in. It never gets your other host directories, your keychain or your SSH agent.
Why run a coding agent in a sandbox at all?An unattended agent can only damage what you hand it: point it at one project and a bad edit or a bad command reaches no further than that project. When you are done, you throw the sandbox away and start clean.
Which coding agents does it support out of the box?Claude Code is built in: the session name claude resolves to the claude-code agent, which asks you to log in inside the sandbox on first run. docs/profiles.md covers running your own agent, and docs/guest-image.md your own guest image.
What are similar projects?coop, nvx, smolvm, box, arcbox, agentbox, CubeSandbox, qwen-code
Which topics is it in?microvm, ai-safety, vm, sandboxing, virtualization, ai-coding, sandbox, apple-silicon, cli-tool, agentic-ai, coding-agent, go
Creator
brig-sh
Size
26.3 MB
Stars
231
Updated
CommitOct 16Releasev0.4.1Oct 16
Age
2mo
Commits · 90 Days