jan-cli 0.18.0

# `jan config`

Emit shell fragments, symlink (or copy) rc files into `$HOME`, run imperative apply
steps, and check host tools declared as `config:` on command nodes.

```bash
jan config emit --shell zsh -o ~/.config/jan/config.zsh
jan config link
jan config apply
jan config deps
```

| Subcommand | Description |
|------------|-------------|
| `emit` | Concatenate all `config.shell` fragments (tree walk order) |
| `link` | Symlink `config.link` sources under the preferred dir into `$HOME` destinations |
| `apply` | Run each `config.apply` argv list |
| `deps` | Report `config.deps` tools missing from `PATH` |

## YAML

```yaml
commands:
  config:
    about: host configuration
    commands:
      zsh:
        config:
          shell:
            path: config/zsh.zsh   # relative to preferred jan dir
          # or inline:
          # shell: |
          #   setopt AUTO_CD
      emacs:
        config:
          link:
            ~/.emacs.d/init.el: config/init.el
      git:
        config:
          apply:
            - [git, config, --global, alias.co, checkout]
      deps-required:
        about: required for full use of scripts
        config:
          deps:
            ag: the_silver_searcher   # bin → optional install hint
            fzf: ""
```

| Field | Meaning |
|-------|---------|
| `shell.path` | File under the preferred jan directory |
| `shell:` (string) | Inline fragment |
| `link` | Map of destination → source. Dest must be absolute or `~/…` under `$HOME` (or `$XDG_CONFIG_HOME`). Source is relative to the preferred dir. |
| `apply` | List of argv arrays (no shell interpolation) |
| `deps` | Map of bare command name → optional package/install hint (empty/`~` = name only). Checked by `jan config deps`. |

Nodes may be config-only (no `run`). They appear in `--help` like alias-only nodes; opening a node that declares `config:` shows a **Host configuration (`jan config`)** section (shell path/inline, links, apply count, deps count). Existing `os:` filters still apply.

The node's `about` (or chain) labels each missing group in the `deps` report.

## Relation to `jan alias`

Do not merge schemas. `aliases:` is for typing less (`alias g=git`, extra jan names). `config:` is for host setup (sourced fragments, symlinks, `git config …`, host tool checklists). See [`alias.md`](alias.md).

## Flags

### `emit`

| Flag | Description |
|------|-------------|
| `--shell sh\|bash\|zsh` | Header dialect (default: `zsh`) |
| `-o`, `--output FILE` | Write to a file instead of stdout |

### `link`

| Flag | Description |
|------|-------------|
| `--dry-run` | Print planned links without changing the filesystem |
| `--copy` | Copy instead of symlink |
| `--force` | Replace an existing destination (default: warn and skip) |

If the destination path already exists, `jan config link` prints a warning to
stderr and skips that entry (exit 0). It does not overwrite unless `--force` is
passed. An existing symlink that already points at the intended source is treated
as done (`ok (already linked)`).

### `apply`

| Flag | Description |
|------|-------------|
| `--dry-run` | Print argv lists without running them |

A non-zero child exit fails the whole `apply`.

### `deps`

| Flag | Description |
|------|-------------|
| `--strict` | Exit `1` if any listed tool is missing (default: exit `0` and still print the report) |

## Install pattern

Same idea as `jan alias`:

```bash
jan config emit --shell zsh -o ~/.config/jan/config.zsh
source ~/.config/jan/config.zsh
jan config link
jan config apply
jan config deps
```

`libbeagan_dependencies` (when emitted from the preferred tree) is a thin wrapper around `jan config deps`.