feat(plugin): add skill support for plugins

[kvnwolf]

Summary

Allows plugins to bundle and expose skills by declaring paths in their return type:

export const MyPlugin: Plugin = async () => ({
  skill: ['./skills/pdf', './skills/docs/*']
})

This addresses a gap where plugins can export tool but not skill, making it difficult to distribute complete packages.

Changes

• Added skill?: string[] to the Hooks interface in @opencode-ai/plugin
• Created SkillRegistry to track skill paths from plugins
• Modified Skill.state() to load skills from the registry with proper precedence:
  1. Global ~/.config/opencode/skill/ (lowest priority)
  2. Plugin skills
  3. Project .claude/skills/
  4. Project .opencode/skill/ (highest priority)
• Added tests for plugin skill loading
• Updated documentation

Related Issues

• Closes [FEATURE]: Add Skill Configuration to Config Type #6013 - Add Skill Configuration to Config Type
• Addresses [FEATURE]: Plugin Hook for Registering Additional Config Directories #6347 - Plugin Hook for Registering Additional Config Directories
• Provides simpler alternative to [FEATURE]: Skill Registry + Installer for Awesome-Claude-Skills (Make OpenCode the One Tool) #8386 - Skill Registry proposal

Why this approach?

As discussed in the issues, instead of creating a separate Skill Registry system or directory hooks, this leverages the existing plugin mechanism. Benefits:

• No new infrastructure - npm remains the distribution mechanism
• Consistent model - plugins can now bundle skills + tools + hooks together
• Simple API - just an array of relative paths with glob support

Testing

bun test packages/opencode/test/skill/plugin-skill.test.ts

All 10 skill tests pass (6 existing + 4 new).

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on my search results, I found one potentially related PR that addresses a similar feature:

Related PR:

• feat(skill): add support for custom skill directories via config #8543 - feat(skill): add support for custom skill directories via config
  • feat(skill): add support for custom skill directories via config #8543
  • This PR adds support for custom skill directories, which is related to the skill distribution mechanism being introduced in PR feat(plugin): add skill support for plugins #9010.

The PR #9010 (current PR) appears to be the primary implementation for plugin skill support. While #8543 addresses a related feature around skill directories, it's a different approach than bundling skills through plugins. They may work together but don't appear to be duplicates—rather, they're complementary features.