clanker-agent/packages/coding-agent/docs/packages.md

> companion can help you create companion packages. Ask it to bundle your extensions, skills, prompt templates, or themes.

# Companion Packages

Companion packages bundle extensions, skills, prompt templates, and themes so you can share them through npm or git. A package can declare resources in `package.json` under the `companion` key, or use conventional directories.

## Table of Contents

- [Install and Manage](#install-and-manage)
- [Package Sources](#package-sources)
- [Creating a Companion Package](#creating-a-companion-package)
- [Package Structure](#package-structure)
- [Dependencies](#dependencies)
- [Package Filtering](#package-filtering)
- [Enable and Disable Resources](#enable-and-disable-resources)
- [Scope and Deduplication](#scope-and-deduplication)

## Install and Manage

> **Security:** Companion packages run with full system access. Extensions execute arbitrary code, and skills can instruct the model to perform any action including running executables. Review source code before installing third-party packages.

```bash
companion install npm:@foo/bar@1.0.0
companion install git:github.com/user/repo@v1
companion install https://github.com/user/repo  # raw URLs work too
companion install /absolute/path/to/package
companion install ./relative/path/to/package

companion remove npm:@foo/bar
companion list    # show installed packages from settings
companion update  # update all non-pinned packages
```

By default, `install` and `remove` write to global settings (`~/.companion/agent/settings.json`). Use `-l` to write to project settings (`.companion/settings.json`) instead. Project settings can be shared with your team, and companion installs any missing packages automatically on startup.

To try a package without installing it, use `--extension` or `-e`. This installs to a temporary directory for the current run only:

```bash
companion -e npm:@foo/bar
companion -e git:github.com/user/repo
```

## Package Sources

Companion accepts three source types in settings and `companion install`.

### npm

```
npm:@scope/pkg@1.2.3
npm:pkg
```

- Versioned specs are pinned and skipped by `companion update`.
- Global installs use `npm install -g`.
- Project installs go under `.companion/npm/`.

### git

```
git:github.com/user/repo@v1
git:git@github.com:user/repo@v1
https://github.com/user/repo@v1
ssh://git@github.com/user/repo@v1
```

- Without `git:` prefix, only protocol URLs are accepted (`https://`, `http://`, `ssh://`, `git://`).
- With `git:` prefix, shorthand formats are accepted, including `github.com/user/repo` and `git@github.com:user/repo`.
- HTTPS and SSH URLs are both supported.
- SSH URLs use your configured SSH keys automatically (respects `~/.ssh/config`).
- For non-interactive runs (for example CI), you can set `GIT_TERMINAL_PROMPT=0` to disable credential prompts and set `GIT_SSH_COMMAND` (for example `ssh -o BatchMode=yes -o ConnectTimeout=5`) to fail fast.
- Refs pin the package and skip `companion update`.
- Cloned to `~/.companion/agent/git/<host>/<path>` (global) or `.companion/git/<host>/<path>` (project).
- Runs `npm install` after clone or pull if `package.json` exists.

**SSH examples:**

```bash
# git@host:path shorthand (requires git: prefix)
companion install git:git@github.com:user/repo

# ssh:// protocol format
companion install ssh://git@github.com/user/repo

# With version ref
companion install git:git@github.com:user/repo@v1.0.0
```

### Local Paths

```
/absolute/path/to/package
./relative/path/to/package
```

Local paths point to files or directories on disk and are added to settings without copying. Relative paths are resolved against the settings file they appear in. If the path is a file, it loads as a single extension. If it is a directory, companion loads resources using package rules.

## Creating a Companion Package

Add a `companion` manifest to `package.json` or use conventional directories. Include the `companion-package` keyword for discoverability.

```json
{
  "name": "my-package",
  "keywords": ["companion-package"],
  "companion": {
    "extensions": ["./extensions"],
    "skills": ["./skills"],
    "prompts": ["./prompts"],
    "themes": ["./themes"]
  }
}
```

Paths are relative to the package root. Arrays support glob patterns and `!exclusions`.

### Gallery Metadata

The [package gallery](https://shittycodingagent.ai/packages) displays packages tagged with `companion-package`. Add `video` or `image` fields to show a preview:

```json
{
  "name": "my-package",
  "keywords": ["companion-package"],
  "companion": {
    "extensions": ["./extensions"],
    "video": "https://example.com/demo.mp4",
    "image": "https://example.com/screenshot.png"
  }
}
```

- **video**: MP4 only. On desktop, autoplays on hover. Clicking opens a fullscreen player.
- **image**: PNG, JPEG, GIF, or WebP. Displayed as a static preview.

If both are set, video takes precedence.

## Package Structure

### Convention Directories

If no `companion` manifest is present, companion auto-discovers resources from these directories:

- `extensions/` loads `.ts` and `.js` files
- `skills/` recursively finds `SKILL.md` folders and loads top-level `.md` files as skills
- `prompts/` loads `.md` files
- `themes/` loads `.json` files

## Dependencies

Third party runtime dependencies belong in `dependencies` in `package.json`. Dependencies that do not register extensions, skills, prompt templates, or themes also belong in `dependencies`. When companion installs a package from npm or git, it runs `npm install`, so those dependencies are installed automatically.

Companion bundles core packages for extensions and skills. If you import any of these, list them in `peerDependencies` with a `"*"` range and do not bundle them: `@mariozechner/companion-ai`, `@mariozechner/companion-agent-core`, `@mariozechner/companion-coding-agent`, `@mariozechner/companion-tui`, `@sinclair/typebox`.

Other companion packages must be bundled in your tarball. Add them to `dependencies` and `bundledDependencies`, then reference their resources through `node_modules/` paths. Companion loads packages with separate module roots, so separate installs do not collide or share modules.

Example:

```json
{
  "dependencies": {
    "shitty-extensions": "^1.0.1"
  },
  "bundledDependencies": ["shitty-extensions"],
  "companion": {
    "extensions": ["extensions", "node_modules/shitty-extensions/extensions"],
    "skills": ["skills", "node_modules/shitty-extensions/skills"]
  }
}
```

## Package Filtering

Filter what a package loads using the object form in settings:

```json
{
  "packages": [
    "npm:simple-pkg",
    {
      "source": "npm:my-package",
      "extensions": ["extensions/*.ts", "!extensions/legacy.ts"],
      "skills": [],
      "prompts": ["prompts/review.md"],
      "themes": ["+themes/legacy.json"]
    }
  ]
}
```

`+path` and `-path` are exact paths relative to the package root.

- Omit a key to load all of that type.
- Use `[]` to load none of that type.
- `!pattern` excludes matches.
- `+path` force-includes an exact path.
- `-path` force-excludes an exact path.
- Filters layer on top of the manifest. They narrow down what is already allowed.

## Enable and Disable Resources

Use `companion config` to enable or disable extensions, skills, prompt templates, and themes from installed packages and local directories. Works for both global (`~/.companion/agent`) and project (`.companion/`) scopes.

## Scope and Deduplication

Packages can appear in both global and project settings. If the same package appears in both, the project entry wins. Identity is determined by:

- npm: package name
- git: repository URL without ref
- local: resolved absolute path