box/README.md

# box

**Headless, trust-less, throwaway dev VMs.** One command mints a fresh,
network-isolated Incus box from a **template**; the coding-agent templates
ship a CLI agent on Debian 13 — `claude` (Claude Code), `codex` (OpenAI
Codex), `grok` (xAI Grok). The box is the product — you log in and work;
destroying it loses nothing you didn't push.

**Strictly creds-free.** A box ships with everything installed and **no**
credentials — no agent token, no git PAT, nothing. You authenticate
interactively *inside* the box. The tool never stores or injects a secret. That
means there's nothing shared or committed, so it's safe for multiple operators
out of the box.

**Templates set what's in the box, never what it can reach.** A template is
image + user + resources + cloud-init; the network and every security flag
live in a shared profile no template can touch, so `blank` is a box with
nobody home — not a box with the safety off.

**The tool knows nothing about your projects.** You just `git clone` inside a
box. A repo can ship an optional [`.box/`](docs/box-recipe.md)
runbook that the box's coding agent reads and acts on — there is no `install`
step and no host-run setup. See [docs/box-design.md](docs/box-design.md) for the
design rationale.

> **0.5.0**: two new templates (`codex`, `grok`), `box expose` — a
> loopback-only door to a box port, for seeing a dev server — and the host
> lifecycle as first-class verbs: `box setup-host`, `box teardown-host`, and
> `box migrate-host`, which re-homes pre-0.4.0 boxes onto the current stack
> and retires the legacy bridge.
>
> **0.4.0's clean cut stands**: the CLI is `box` (no legacy shim), the
> host stack is `boxnet`/`box-isolate`/`box-firewall` on 10.88.0.0/24, and
> the default template is `blank`. Boxes minted by any earlier version keep
> working under every verb — their legacy tag is honored forever.

## Install

```sh
curl -fsSL https://raw.githubusercontent.com/heavy-duty/box/main/install.sh | bash
```

Installs the tree to `~/.local/share/box` and links `box` onto your
`PATH`, then runs the host setup below for you (it may ask for `sudo`; set
`BOX_SKIP_SETUP_HOST=1` to opt out and run it yourself). Re-run any time to
upgrade — upgrading re-applies the host stack, and from a pre-0.4.0 install
also retires the old `claudebox` symlink. (No `git clone` needed.)

## One-time host setup (Ubuntu 24.04 / Debian 13)

The installer already does this. Run it directly to set up a host you
installed with `BOX_SKIP_SETUP_HOST=1`, or to re-apply the stack by hand:

```sh
box setup-host   # one run is enough
```

Idempotent. Installs Incus and creates the isolation stack: the `boxnet` NAT
bridge (sibling-name resolution off, resolver pinned to public upstreams —
`BOX_DNS` overrides), the `box-isolate` ACL (drops all RFC1918/CGNAT/
link-local egress), the `box-net` profile (port-isolated NICs — boxes can't
reach each other), and firewall rules blocking instance → host. All rules
re-apply at boot via `box-firewall.service` — no post-reboot ritual. If
the host lacks `dnsmasq-base` (Debian cloud images skip Recommends):
`sudo apt-get install -y dnsmasq-base`.

A host still carrying the pre-0.4.0 stack: `box migrate-host --all-boxes`
re-homes each legacy box onto `boxnet` (authed state preserved), and
`box migrate-host --retire-legacy` removes the old bridge and profile once no
legacy box remains.

## Quick start

```sh
box new --name work --template claude   # a creds-free coding-agent box (~10 min cold)
box shell work                   # enter as the template's user
```

Pick whichever coding-agent template you like — `claude`, `codex`, `grok` — or
`blank` for none. Inside the box, authenticate as needed. The `claude` template
looks like this; the others follow the same shape with their own login step:

```sh
claude                           # then run /login — copy the URL (press c), open it
                                 #   in YOUR browser, paste the code back. No host CLI needed.
gh auth login                    # or drop a PAT in — your git credentials, your call
git clone https://github.com/you/project && cd project
claude                           # if the repo has .box/, the agent reads it and sets up
```

## Templates

No coding agent is special — each is one template among several, and adding
another is just another directory. What ships today:

| Template | What's in it |
| --- | --- |
| `blank`  | Bare Debian 13 — same isolation, no tooling. The default. |
| `claude` | Claude Code, creds-free — where this project started |
| `codex`  | OpenAI Codex CLI, creds-free |
| `grok`   | xAI Grok CLI, creds-free |

A template is a directory under `templates/`: a `box.env` (image, user,
resources — parsed against a strict allowlist, never sourced) and a
`user-data.yaml` (cloud-init, passed to Incus verbatim). The coding-CLI
templates are all the same shape — install the CLI, put it on PATH, drop an
agent-context file; none of them carry credentials.

```sh
box templates                    # list what this install can mint
box new --name scratch           # the DEFAULT template is blank: bare Debian,
                                 #   same isolation, nobody home
```

A template **cannot** name a network, a profile, or a `security.*` flag —
there is no key for them. Every box launches with the shared `box-net`
profile (the isolated NIC + root disk), so every template gets the identical
trust boundary. Resources come from the template's `box.env`, overridable at
mint time — inline (`--cpu 2 --memory 3GiB --disk 20GiB`) or via
`BOX_CPU` / `BOX_MEMORY` / `BOX_DISK` environment variables (the scripting
form; flags win). The template's identity (name, user) is stamped onto the instance,
so `shell`, `exec` and `tmux` land in the right user — and a clone still
knows, because `incus copy` carries the metadata.

## Log in once, reuse via snapshots

Because every fresh box is creds-free, re-authenticating each time would be
toil. Snapshot an authenticated box and clone from it instead:

```sh
box snapshot work authed   # checkpoint after you've logged in
box new --name feature --from work/authed   # clone the authed state into a new box
```

`--from` copies the whole box (agent login, git creds, clones and all) while
preserving isolation. You can also `box new --name x --from work` to clone
a box's live state, or roll a box back with `box restore work authed`.

Forgotten what you called a checkpoint? `box info work` prints the box's
snapshot labels and the `--from` line to clone one.

## See a dev server: `box expose`

The isolation contract says no inbound path exists — which is one "no" too
many when you're coding in a box and want its dev server in your browser.
`box expose` is the deliberate exception:

```sh
box expose work 3000             # http://127.0.0.1:3000 → work:3000
box expose work 3000 8080        # or pick the host port: 127.0.0.1:8080 → work:3000
box expose work --list           # what doors are open
box expose work --remove 3000    # close one
```

The listen side is **always the host's own loopback** — never the network, no
flag to widen it — so no other machine gains a path to the box. The in-box
server must listen on `0.0.0.0`, not its own loopback (safe inside the
isolation stack: only this door can reach it). A box with a hole says so:
`box info` lists open exposures. Everything else on the box stays dropped —
the door is per-port, punched and removable at runtime.

## Commands

```
box new --name <box> [--template <t>] [--from <src>[/<snap>]] [--cpu <n>] [--memory <size>] [--disk <size>] [--vm|--container]
box templates                # list the templates this install can mint
box list                     # list your boxes
box info <box>               # one box: state, IP, exposures, snapshot labels
box shell <box>              # enter as the template's user
box exec <box> -- <cmd...>   # run a command in the box
box tmux <box> [session]     # attach/create a tmux session — survives disconnects
box snapshot <box> [label]   # checkpoint (label defaults to manual-<epoch>)
box restore <box> <snap>     # roll back to a snapshot
box rename <box> <new>       # rename a box (stop it first)
box down <box>               # stop (state kept; `start` resumes)
box start <box>              # start a stopped box
box rm <box> [--force]       # delete the box + its snapshots (asks first)
box expose <box> <port> [<host-port>] | --list | --remove <port>
                             # forward a box port to host loopback — see a dev server
box incus <box> -- <args...> # escape hatch: any incus command, box resolved
box doctor [--fix|--pin-dns] # is this host fit to mint boxes? diagnose from ground truth
box setup-host               # one-time host setup: Incus, the boxnet stack, the firewall
box teardown-host [--purge-incus]   # remove the host stack (both name generations)
box migrate-host --box <n> | --all-boxes | --retire-legacy
                             # move a pre-0.4.0 host onto the box stack
box status                   # deprecated alias for `list`
box help [<command>]         # full help, or one command's page
```

Every command takes `--help`, and options come after the command
(`box list --json`). Exit status: `0` ok, `1` it went wrong, `2` you asked
wrong.

`new` fresh-launches from a template (default: `blank`), or with `--from`
clones an existing box or snapshot. VM mode (`--vm`, the default where
`/dev/kvm` exists) is the trust-less target; container mode (auto-fallback,
`security.nesting=true`) is for hosts without nested virt — weaker isolation,
dev/test only.

## Boxes are just Incus instances

A box is an ordinary Incus instance tagged `user.box=1` (pre-0.4.0 boxes
carry `user.claudebox=1`, honored forever). box wraps the box lifecycle and
the isolation model — not all of Incus. It owns a command
when it must enforce something Incus can't see: that tag (it will not stop,
rename or delete an instance it didn't mint), the isolation stack, or the
creds-free snapshot workflow. For everything else, there's the door:

```sh
box incus work -- config show        # instance name appended
box incus work -- file push x.tar {}/tmp/   # or placed with {}
```

The box is resolved and tag-checked; the rest is passed to `incus` verbatim, and
the command is echoed before it runs. If it can move the box off the isolation
stack (profile, network, device, `security.*`), box warns and proceeds —
the trust boundary is then yours to keep. See
[docs/box-design.md](docs/box-design.md) for the rule and why the
command surface is a table.

## Isolation

The contract: **a box reaches the public internet and nothing else.** Not the
host, not your LAN, not another box, not even another box's *name*. What
enforces it, layer by layer:

- **Dedicated NAT bridge** `boxnet`, IPv6 off. Every rule below is
  IPv4-only, so IPv6 would be an uncovered path — off is part of the
  contract, not a default.
- **`box-isolate` ACL** — drops all egress to private space (RFC1918,
  CGNAT, link-local), with a single carve-out to the gateway so DNS works.
- **Sibling isolation, at L2** — two boxes on one bridge are *switched*,
  never routed, so no L3 rule can separate them (learned the hard way; see
  below). `security.port_isolation` on every box NIC plus an nft
  bridge-family drop mean box A cannot exchange frames with box B at all.
- **No name-level reconnaissance** — `dns.mode=none` stops the gateway
  resolving sibling names, and the bridge's resolver is pinned to public
  upstreams (`no-resolv`), so tailnet names and split-DNS zones from a
  host-level VPN don't resolve inside a box either.
- **Host firewall** — instance → host is dropped except DNS/DHCP, including
  the host's public IPs. Entry is `incus exec` over the local socket only —
  **no inbound path exists** — unless you punch one with `box expose`, and
  that door only ever opens onto the host's own loopback (`127.0.0.1`), never
  the network.

The VM is the trust boundary: whatever runs inside — the coding agent, or
anything a template ships — can run arbitrary code and touch nothing you care
about.

### Measured, not claimed

Every clause above is probed live by an end-to-end drill, because the one time
this contract was reasoned about instead of measured, the reasoning was wrong:
box→box traffic was "covered" by an L3 drop that L2-switched frames never
meet — a hole found by probing, not by reading the rules. On a bare host the
drill installs the whole stack, mints every template cold, snapshots and
clones, probes every boundary from inside the boxes, opens and shuts the
`expose` door (and checks the contract survives it), re-homes a faithful
pre-0.4.0 box through `migrate-host`, and removes what it minted —
currently **84 checks, 84 passing**. [drill/RUNS.md](drill/RUNS.md) is the full
history, including every trap that fooled a run into a wrong verdict.

### Run the drill yourself

The drill ships in the repo, not the installed tree — run it from a checkout.
Two versions are in play and both must be current: **the drill script you
run** (a stale checkout judges the past), and **the code under test** — the
drill does not test your working tree; it installs box from GitHub
(default: `heavy-duty/box@main`) and asserts the installed tree is exactly
the ref it asked for before issuing any verdict.

```sh
git clone https://github.com/heavy-duty/box && cd box   # or refresh an existing
git log --oneline -1                                    #   checkout — this commit is
                                                        #   the drill that will judge
bash drill/doctor.sh    # read-only: is this host healthy and the stack live?
bash drill/drill.sh     # FULL end-to-end — mutates the host; use a machine you own
bash drill/wipe.sh      # scorched earth: strip BOTH name generations, images and
                        #   (--purge-storage) the pool, so a run starts from bare
```

To drill something other than latest `main` — a release ref, or a PR branch
on a fork:

```sh
bash drill/drill.sh --ref <branch-or-tag>
bash drill/drill.sh --repo <owner>/<repo> --ref <branch>   # a PR under review
```

The doctor reads ground truth, not config claims — the kernel's `isolated on`
flag per bridge port, the process table, the resolver actually in use — and
diagnoses the host faults that have actually happened: a wedged Incus daemon,
a dnsmasq that silently isn't serving, a VPN resolver that boxes would
inherit.

## Recipes: the `.box/` convention

A repo that wants to be easy to stand up in a box ships an optional `.box/`
folder — a runbook the box's coding agent reads and follows (install deps,
start services, template env, seed data, smoke-test). It is agent-facing
documentation, not a host-executed script. See
[docs/box-recipe.md](docs/box-recipe.md).

## Uninstall

```sh
box teardown-host                # boxes, network, ACL, profile, firewall
box teardown-host --purge-incus  # ...and Incus itself
rm -rf ~/.local/share/box ~/.local/bin/box   # the CLI itself
```

## Non-goals

- **No unattended/CI bring-up.** The flow is interactive (log in, clone, ask
  the agent). Reproducible-by-construction provisioning is out of scope.
- **No credential storage or injection by the tool.** Boxes are creds-free;
  snapshots are the reuse mechanism, not a secrets store.