# AGENTS.md

Conventions for working in this tree. They apply to every commit; the
whole history follows them.

## Before every commit

Run, in order, and make sure they are clean before committing:

```sh
cargo fmt --all
cargo clippy --all-targets   # no new warnings
cargo test                   # keep green when touching behavior
```

These mirror CI (`.github/workflows/ci.yml` runs check, `fmt --check`,
clippy, and `cargo test --all-features`). `cargo fmt` may amend files
you did not touch — include those changes in the commit (or in a
separate `chore:` commit) rather than leaving the tree dirty.

## Commit messages

Follow Conventional Commits with a component scope:

```
<type>(<scope>): <short summary>
```

Rules:

- Types: `feat`, `fix`, `refactor`, `perf`, `test`, `docs`, `build`,
  `ci`, `chore`.
- Scopes match the component touched — the module name under `src/`:
  - `cli` — entry point and flags (`src/main.rs`, `src/cli.rs`)
  - `config` — config file (`src/config.rs`)
  - `distro` — distro definitions and mirrors (`src/distro.rs`)
  - `download` — image download (`src/download.rs`)
  - `extract` — rootfs extraction (`src/extract.rs`)
  - `chroot` — chroot setup (`src/chroot.rs`)
  - `namespace` — Linux namespaces (`src/namespace.rs`)
  - `mount` — bind mounts and mount table (`src/mount.rs`)
  - `kernel` — kernel/initramfs handling for `--kernel` (`src/kernel.rs`)
  - `qemu` — QEMU VM mode (`src/qemu.rs`, `src/qemu_vm.rs`)
  - `utils`, `verbose` — shared helpers (`src/utils.rs`,
    `src/verbose.rs`)
  - `deps` — dependency additions/bumps (manifests, lockfile)
- Omit the scope entirely for repo-wide changes that do not belong to a
  single component (README.md, SPEC.md, root config).
- Summary: imperative mood ("add", never "added" or "adds"), lowercase
  first letter, no trailing period, max ~72 characters.
- Body (optional): separated by a blank line, wrapped at 72 columns;
  explain why rather than what. Reference issues as `#123`.
- A commit touching several components should be split into one commit
  per component when practical; otherwise use the dominant scope.
- **No merge commits.** Integrate work by rebasing onto the target
  branch (`git rebase`, `git pull --rebase`, `git cherry-pick`); the
  history stays linear. When several work streams run in parallel, land
  them one rebase at a time.

### Examples

```
feat(namespace): set unique hostname per run
fix(extract): handle hard links in rootfs archives
fix(kernel): parse =PATH syntax for --kernel
test(chroot): cover path resolution helpers
feat(qemu): enable KVM when available
deps: bump nix to 0.31
docs: document QEMU system mode and =PATH syntax
chore: apply cargo fmt
```

## Code

- Tests live inline as `#[cfg(test)]` modules at the bottom of each
  `src/` module; there is no `tests/` directory. Scope test commits to
  the module under test.
- Comments state constraints the code cannot show; no narration.
- Anything user-facing (CLI flags, config keys, error text users act
  on) is reflected in `README.md` before commit.
- Design decisions that outlive the session go to `SPEC.md`, not to
  new docs or repos.