Create Opencode Plugin

This is a comprehensive workflow guide for building OpenCode plugins using their SDK. It walks you through the full lifecycle: verifying API references, validating feasibility (what's possible vs. what requires core changes), designing hooks, implementing with modular TypeScript patterns, adding UI feedback, testing, and publishing. The structure is opinionated about code organization, insisting you split complex plugins into multiple focused files instead of dumping everything in index.ts. Most valuable for the feasibility check, it explicitly lists what you can't do with plugins (modify TUI, add keybinds, change core prompts) so you don't waste time on impossible approaches. The hook patterns and examples cover the common use cases: intercepting tool calls, reacting to file edits, adding custom tools, building auth providers.