Plugins

A plugin bundles related customizations — skills, hooks, sub-agent definitions, MCP server configs, and output styles — into a single installable directory. The plugin system (ADR 0030) is a thin orchestrator: it parses a plugin.json manifest, namespaces items, expands ${CALIBAN_PLUGIN_ROOT}, and is designed to feed everything into the same per-surface loaders that project and user files use.

What a plugin contains

my-plugin/
  plugin.json             # required manifest
  skills/
    my-workflow/
      SKILL.md
  hooks/
    hooks.json
  agents/
    reviewer.md
  output-styles/
    concise.md
  mcp/
    .mcp.json
  commands/
    recap.md

All subdirectories are optional. When a components entry is omitted from the manifest, the loader scans the conventional subdirectory automatically.

The manifest (plugin.json)

{
  "name": "my-plugin",
  "version": "1.0.0",
  "description": "Short description shown in /plugins and trust prompts",
  "author": "Alice <alice@example.com>",
  "license": "MIT",
  "homepage": "https://example.com/my-plugin",
  "components": {
    "skills": ["skills/my-workflow"],
    "hooks": "hooks/hooks.json",
    "agents": ["agents/reviewer.md"],
    "output_styles": "output-styles/concise.md",
    "mcp_servers": "mcp/.mcp.json",
    "commands": ["commands/recap.md"]
  },
  "caliban": {
    "min_version": "0.5.0",
    "platforms": ["macos", "linux"]
  }
}

For MCP servers bundled as inline config (matching Claude Code's .mcp.json shape), use the top-level mcpServers key instead of components.mcp_servers.

Discovery roots

Caliban scans three roots at startup. A plugin with the same name in an earlier root replaces later ones — no manifest merging.

Which plugins load is filtered at startup by the CALIBAN_ENABLED_PLUGINS environment variable (comma-separated names). Managed plugins ignore the filter. caliban plugin enable/disable records the choice in the plugins.enabled setting, but startup does not read that setting yet.

Namespacing

Items loaded from a plugin carry a <plugin>:<item> prefix:

• Skills: my-plugin:my-workflow
• Output styles: my-plugin:concise
• MCP servers: my-plugin:my-server

This prevents collisions with bare-named items at the project or user level. Hooks merge additively across plugins.

The caliban plugin command

# List all installed plugins and their status
caliban plugin list

# Show the manifest of an installed plugin as JSON
caliban plugin info <name>

# Install a plugin from a marketplace
caliban plugin install <name>@<marketplace-url>

# Install a plugin from a local directory
caliban plugin install --dir /path/to/my-plugin

# Update a plugin to the latest marketplace version
caliban plugin update <name>

# Remove a plugin
caliban plugin remove <name>

# Enable / disable a plugin (affects whether it loads at startup)
caliban plugin enable <name>
caliban plugin disable <name>

caliban plugin help prints the full reference.

Marketplace trust

First-time marketplace installs display the manifest, its sha256 hash, and the install URL and prompt for acknowledgement. Acknowledged installs are recorded in $XDG_DATA_HOME/caliban/trust/plugins.json. Re-installs of the same manifest hash skip the prompt; version bumps re-prompt. Sideloads (local --dir installs) skip trust gating because the operator already has filesystem access.

${CALIBAN_PLUGIN_ROOT} expansion

Inside plugin-bundled hook commands and MCP server configs, ${CALIBAN_PLUGIN_ROOT} expands to the plugin's absolute root directory. ${CLAUDE_PLUGIN_ROOT} is a supported alias so existing Claude Code plugins port verbatim.

Related pages

• Skills
• Hooks
• MCP Servers
• Output Styles
• Slash Command Index — /plugins overlay