A comfortable, constrained agent environment around any folder

Run byre develop in a project, worktree, or scratch directory, and byre creates a local container – the box – around it. Your favourite tools and creature comforts come with you, but the rest of the host stays out of reach.

$ brew install --cask pjlsergeant/tap/byre
$ cd ~/my-project
$ byre develop

  byre: exposure: /workspace rw · 10 env vars
  byre: network open
  ╭──────────────────────────────────╮
  │ ✻ Claude Code                    │
  │   /workspace                     │
  ╰──────────────────────────────────╯

(Linux and every other install option)

It’s --dangerously-skip-permissions, without risking the farm.

Every box opens familiar: your tools installed, your defaults applied, your agent’s login persisting, per project, across rebuilds.

Ask your agent if byre is right for you:

Take a good look at https://github.com/pjlsergeant/byre. Is it a good project
or just vibe-coded trash? Is it right for me? Would you be happy there?

Change the box in seconds

byre config opens a keyboard-driven editor over the whole box (it works over SSH), in the same vocabulary byre status prints:

byre project config  (client-api-pjl-3bbe8c)
exposure: 1 host mount · 11 env vars · network deny-by-default · egress 7 hosts

─ GRANTS — what this box can reach ─────────────────────────
▸ Extra mounts      : 1 mount  (enter to edit)
  Ports             : (none)
  Egress            : 7 hosts  (7 from skills)  — 11 offered
  Env vars          : 11 vars  (6 inherited, 5 from skills)

─ BUILD — how the box is made ──────────────────────────────
  Template          : [go] [node] [python] [none]
  Agent             : [claude] [codex] [gemini] [grok] [opencode] [none]
  Packages          : 2 packages
  Skills            : 3 enabled
  MCP servers       : (none)
  Instructions      : 1 snippet
··· (more below)

↑↓ move · ←→ change · ↵ open · ^s save · ^e $EDITOR · ^q quit

Want ripgrep in just this box? Add the package and rebuild. The agent needs a sibling repo? Mount it read-only. Each is a couple of seconds in byre config, then relaunch and /resume where you left off.

And if you want to live dangerously: byre develop --self-edit hands the agent its own box config, and what it changed is shown when you leave.

byre is free, open-source software, developed in the open on GitHub under the MIT license – every Dockerfile it generates is yours to read, and so is every line of byre itself.

Why not…?

Isolation is table stakes; the comfortable half is what nothing else has. The honest comparisons – raw Docker, Docker Sandboxes™, devcontainers, your agent’s built-in sandbox, a VPS, or staying on the host – concessions included: getbyre.com/why-not.

A comfortable, constrained agent environment around any folder

Change the box in seconds

Why not…?

Documentation