# Working on Sausage

Sausage is meant to be read and changed by agents, including its own agent.
Keep it that way.

## Priorities

1. **Correct.** Every behavior in `PROTOCOL.md` has a test in `cli/tests/`.
2. **Simple and short.** Prefer the obvious code. No abstraction for one
   caller. No configuration that nobody asked for.
3. **Readable.** A new reader must understand a file without the others.
   Each module starts with a doc comment that says what it owns.
4. **Efficient** on the paths that run per message.
5. **Raw and minimal.** Sausage has no permissions, sandboxing beyond WASI,
   limits, or authentication. Do not add them to the core. Add nothing to
   the host that an actor (or the agent, by changing itself) could do.

## Layout

- `cli/`: the host (`sausage` binary and library).
  - `lib.rs`: `Host`, which starts and stops a world.
  - `broker.rs`: routing, mailboxes, the version store, broker requests.
  - `supervisor.rs`: runs one WASM actor (restarts, swaps, rollbacks).
  - `runtime.rs`: Wasmtime instances and what they get (mounts, network).
  - `candidate.rs`: tests a new version. `cargo_actor.rs`: builds Rust.
  - `world.rs`: the on-disk layout. `console.rs`: the terminal.
- `sdk/`: `sausage-actor`, the SDK for Rust actors. Never published: the
  `cargo` actor points `sausage-actor = "0.1"` at its local copy.
- `agent/`: the agent actor. `sausage init` embeds and builds it.
- `examples/`: small actors. They are not workspace members.
- `PROTOCOL.md`: the contract between the host and the actors. Change it in
  the same commit as the behavior. `DECISIONS.md` says why; when the two
  disagree, `PROTOCOL.md` and the code win.

## Checks

```sh
nix develop -c cargo test -p sausage -p sausage-actor -p agent
nix develop -c cargo build --release -p agent --target wasm32-wasip2
nix develop -c cargo clippy --workspace
```

`nix run -- init` and `nix run -- run` must keep working without other
setup.