developing-opencode-meta

<essential_principles> This skill covers building extensions for OpenCode, an open-source AI coding assistant. OpenCode's plugin system allows customizing agents, tools, hooks, and more.

1. Plugins are the extension mechanism Everything in OpenCode is extended through plugins. A plugin is a TypeScript function that returns configuration for agents, tools, hooks, and other features. Plugins can be distributed via npm.

2. Agents define AI behaviour Agents are configured AI assistants with specific prompts, models, and tool access. OpenCode has two modes: primary (main agent) and subagent (delegated tasks). Agent prompts are full TypeScript strings, giving complete control.

3. Hooks intercept lifecycle events Hooks let plugins react to events like tool execution, session creation, context limits, and more. They enable features like auto-compaction, TDD enforcement, and context monitoring.

4. Tools extend agent capabilities Custom tools give agents new abilities. Tools are defined with Zod schemas for parameters and can access the plugin context for session management, file operations, etc.

5. Skills work differently in OpenCode OpenCode can load Claude Code skills, but also has its own skill system. Skills in OpenCode are simpler — markdown files that agents can invoke for domain knowledge. </essential_principles>