Files
ai-sandbox/AGENTS.md
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ducoterra 8ee535f6ae bridge the host pi config, with the credential by env only
The image ships pi with no provider and no preferences, so a sandboxed run
meant configuring the model twice. ai-sandbox now reads the host
~/.pi/agent/{models,settings}.json and rewrites them instead of copying them:
every provider apiKey becomes "$AI_API_TOKEN" (pi resolves an env reference
itself, so no value is written to disk), '!command' header values are dropped
rather than executed, settings that point into $HOME are dropped because that
path is not mounted, and auth.json / models-store.json / sessions / extensions
are never read.

The rewritten pair is seeded into /home/sandbox/.pi/agent at container start,
owned by uid 1000 and mode 600, and is treated as managed: a host change is
re-seeded, an edit made inside the sandbox is kept and reported, a deletion
takes the host version again.

The token follows the existing environment rules -- one variable, passed by
name through the 0600 env file, announced when auto-passed. A bridged run
whose token variable is unset or empty is refused instead of starting a pi
that cannot reach its model, and the bridge never widens the allowlist: it
warns with the exact --allow to add.

Docs and examples now use a self-hosted gateway (https://aipi.reeseapps.com)
instead of vendor API endpoints, since that is the only thing this tool is
used against. 391 assertions pass (make lint, ./tests/run.sh --e2e).

LLM-Generated: true
2026-10-27 17:29:17 -04:00

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Markdown

# AGENTS.md
Working notes for anyone (human or agent) changing this repository.
## What this project is
One bash script, `bin/ai-sandbox`, that runs another program — usually an LLM
coding harness — inside a rootless podman container with a strict, explicit policy:
only the current directory mounted, no inherited environment, no root or
capabilities inside the container, resource caps, and egress limited to an
allowlist that the sandboxed process cannot lift.
## Non-negotiables
1. **Single script.** The Containerfile, the container entrypoint, the squid
config, the nftables rules and the bridged pi config are all generated from
`bin/ai-sandbox` (`containerfile()`, `entrypoint_script()`, `write_squid_conf()`,
`gen_rules()` inside the entrypoint, `pi_config_bridge()`). Keep it that way; do
not split policy into files that can drift from the script.
2. **Fail closed.** Any path where the sandbox cannot guarantee its policy must
refuse to start rather than degrade: no allowlist in `allow` mode, missing
policy file in the entrypoint (exit 78), ruleset that cannot be installed
(exit 77), `--env NAME` where NAME is unset, a bridged pi config whose credential
variable is unset *or empty*. Escape hatches exist but must be explicitly named
(`--allow-unenforced`, `--insecure-keep-root`, `--net full`, `--no-pi-config`).
3. **Never leak a secret.** Values go through a `0600` env file, never argv.
Nothing that prints (`--dry-run`, `--print-policy`, the session log, error
messages) may echo a value. If you add output, add a test that a canary value
does not appear in it. The pi bridge is the case that tests this hardest: it reads
a file that may hold a live key, so it rewrites `apiKey` to `"$VAR"`, drops
`!command` values instead of running them, never touches `auth.json`, and
`tests/unit/08_pi_config.sh` asserts a canary secret from the host agent directory
appears nowhere in ai-sandbox state.
4. **No hardcoded machine paths, usernames or ports.** Everything is overridable
via `AISB_*` or a config file; defaults must work for any user on any host.
5. **Measure, don't assume, about podman.** Rootless networking varies by version
and distro. Run `tests/spike_network.sh` on a new host and update
`docs/networking.md` when reality disagrees with the design.
6. **Nothing about a build may be silently mutable.** The base enters the
Containerfile as a digest, and that digest is part of `image_hash()`; Node is
version-pinned and checksum-verified; `pi` is version-pinned. A refresh is an
explicit, dated event (`update`); a build with no digest is announced as `UNPINNED`
and labelled that way; preview modes must never reach the network. If you add a
dependency, decide which of those three it is and cover it in
`tests/unit/07_base.sh` or `tests/e2e/10_image.sh`.
## Layout
```
bin/ai-sandbox the application
install.sh symlink + optional alias
config/*.example documented examples (never loaded directly)
docs/networking.md the measurements behind the enforcement model
docs/threat-model.md what is and is not protected -- keep it honest
docs/recipes.md per-harness and per-language setups
tests/run.sh runner: unit (no containers) | --e2e (real containers)
tests/spike_network.sh re-measure the host
```
## Commands
```bash
make test # unit tests -- fast, no containers, no network
make e2e # plus real container/egress tests (needs network + the image)
make lint # shellcheck in a container
make style # bash -n on every shell file
make check # lint + unit
./bin/ai-sandbox --dry-run --allow example.com --print-policy # introspection
```
Before finishing a change: `make check` green, and if you touched enforcement,
networking or the image, `make e2e` green too.
## Conventions
* bash ≥ 4.4, `set -Eeuo pipefail` in the main script; `set -uo pipefail` in the
test runner (assertions report, they do not abort).
* Option flow is always: defaults → config files → `AISB_*` env → CLI flags.
The built-in defaults live in `resolve_opts()`; the top of the script only sets
variables that have no config-file counterpart. Breaking this is the single
easiest way to introduce a precedence bug.
* `POL[...]` holds resolved policy, `P_*` arrays resolved lists, `OPT_*` raw flags,
`CFG_*` config-file values. Do not read raw env vars deep in the code. A helper
called as `X="$(helper)"` runs in a subshell: it can return text, but any `POL[..]`
it assigns is discarded — return a value and assign it in the caller (see
`base_pin_digest()` + `base_ref_of()`).
* Preview paths (`--dry-run`, `--print-policy`, `--print-entrypoint`,
`--print-containerfile`) must not build images, start containers, write state or
reach the network. That is why digest resolution has a `cache_only` mode, and why
`inspect` (asks the machine now) is a separate surface from `--print-*` (which stays
deterministic and scriptable).
* Tests use `t_name` + `assert_*` from `tests/lib.sh`; each file gets its own
`AISB_STATE_DIR`/`AISB_CACHE_DIR`/`AISB_CONFIG_DIR`. Never let a test touch the
real `~/.config`, `~/.local/state` or `~/.cache`, and never override `HOME`
(podman storage lives there).
## Areas that deserve the most care
* `entrypoint_script()` — the enforcement half. It is rendered into the image and
runs as root there. A bug here is a security bug. `tests/unit/06_entrypoint.sh`
checks the generated rule shape; `tests/e2e/11_net.sh` checks it in a container.
* `split_target()` / `classify_allows()` — the mapping from what the user typed to
what the firewall and the proxy enforce.
* `build_argv()` — every isolation flag lives here.