HostPlugin

Author and publish plugins for coding-agent hosts.

HostPlugin inspects a project or CLI, maps the requested behavior onto each host's native plugin components, and previews the affected files. It creates standalone or embedded plugins, updates existing ones, and publishes them when requested.

Install

HostPlugin supports Codex, Claude Code, Grok Build, GitHub Copilot CLI, OpenCode v2 (2.x), and Cursor. It also supports the vendor-neutral Agent Plugins 1.0.0 portable package standard.

Codex

codex plugin marketplace add baldaworks/hostplugin
codex plugin add hostplugin@hostplugin

Invoke with $hostplugin:author.

Claude Code

claude plugin marketplace add baldaworks/hostplugin
claude plugin install hostplugin@hostplugin --scope user

Invoke with /hostplugin:author.

Grok Build

grok plugin install 'baldaworks/hostplugin#plugins/hostplugin' --trust

Invoke with /hostplugin-author.

GitHub Copilot CLI

copilot plugin marketplace add baldaworks/hostplugin
copilot plugin install hostplugin@hostplugin

Invoke with /hostplugin-author.

Cursor

agent plugin marketplace add https://github.com/baldaworks/hostplugin.git

Then install HostPlugin from the marketplace UI and invoke the hostplugin-author skill.

OpenCode v2

Requires OpenCode 2.x (opencode --version). Install the host with @opencode/cli following the official installation guide.

Install HostPlugin from its GitHub release:

opencode plugin add 'github:baldaworks/hostplugin#v0.3.0'

Invoke with /hostplugin-author. The package registers the bundled skill and keeps its supporting references available from the installed package.

Agent Plugins 1.0.0

The directory plugins/hostplugin is an Agent Plugins 1.0.0 package. A compatible client can load that directory through its documented local-plugin or installation workflow. The Agent Plugins standard itself does not define a universal installation command, marketplace, registry, or invocation syntax.

Use

Describe the plugin outcome in natural language:

$hostplugin:author Inspect this repository and write a plugin for using its CLI on all supported hosts.

HostPlugin performs read-only repository and CLI discovery, asks only for missing product decisions, and presents:

1. a host-by-component capability report;
2. metadata, invocation names, prerequisites, and security effects;
3. the exact file manifest and concise diff;
4. validation commands and known limitations.

Confirm the file preview before HostPlugin writes the proposed plugin. An explicit publication request authorizes the routine publication steps for the agreed destination and scope. Unsupported components are reported and require a decision to remove the target, remove the component, or explicitly redesign it.

Create and publish an OpenCode v2 plugin

For example, invoke HostPlugin in OpenCode with:

/hostplugin-author Create an OpenCode v2 plugin for this repository's CLI and publish it to our GitHub repository acme/opencode-plugin.

Replace acme/opencode-plugin with your destination. HostPlugin prepares the native package.json, plugin entrypoint, and bundled resources; checks the package contents; and follows the repository's release workflow. You can also request publication to an npm registry. Git distribution does not require an npm publication.

Users install the resulting plugins with OpenCode's native commands. These are example package names and repositories to replace with your published destination:

opencode plugin add @acme/opencode-plugin@latest
opencode plugin add github:acme/opencode-plugin
opencode plugin add git+ssh://git@github.com/acme/opencode-plugin.git#main
opencode plugin add 'github:acme/plugins#main::path:packages/opencode-plugin'

Use a specific npm version or Git tag/commit for a fixed release. The last example selects a package inside a repository. These commands install the native plugins you create; to install the HostPlugin authoring skill itself, use the OpenCode instructions above.

See the OpenCode packaging and publication reference for package checks and release steps, and the official OpenCode plugin guide for installation options.

Components

HostPlugin understands the current native component families of each host, including skills, commands, agents, hooks, MCP and LSP integrations, rules, Codex apps, Cursor subagents, and OpenCode JS/TS plugins. It also understands the Agent Plugins 1.0.0 portable core: Agent Skills and MCP servers in fixed package locations. Other component families are not portable Agent Plugins components and are never translated silently.

Provider and portable-standard contracts are pinned under plugins/hostplugin/references/ and include their review date and official sources. Installed host help and native validators take precedence when they reveal a newer contract.

Development

Run the dependency-free contract suite:

python3 -m unittest discover -s tests -v

Then validate the canonical and prefixed skills, the Codex plugin, and available native host manifests. See AGENTS.md for the required completion checks.

License

HostPlugin is available under the MIT License.