chore: add project docs, glossary, research and opencode/fastcrw skills

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.claude/skills/opencode-v2-plugin/SKILL.md

@@ -0,0 +1,65 @@
+---
+name: opencode-v2-plugin
+description: How to write, configure and register an opencode v2 plugin, including adding a websearch provider. Use when writing or editing plugin code, opencode.json `plugins`/`websearch` config, or plugin packaging in this repo.
+---
+
+# opencode v2 plugin
+
+Verified against opencode.ai/v2 docs (build/plugins, plugins, config, websearch). Full evidence and open items: `docs/research/opencode-v2-plugin-api.md`. The v1 package `@opencode-ai/plugin` does NOT run in v2.
+
+## Entry point
+
+```ts
+import { Plugin } from "@opencode/plugin"
+
+export default Plugin.define({
+  id: "home.fastcrw", // required, stable; used for storage scoping and diagnostics
+  async setup(ctx) {
+    // ctx.options (plugin options), ctx.storage, ctx.location, ctx.websearch, ...
+    // may return a cleanup function
+  },
+})
+```
+
+Options are read from `ctx.options` inside `setup`, not passed as an argument. They are untyped key/value: validate them yourself.
+
+## Websearch provider
+
+```ts
+await ctx.websearch.transform((editor) => {
+  editor.add({
+    id: "fastcrw",
+    name: "fastCRW (self-hosted)",
+    execute: async ({ query }, { signal }) => [{ url, title, content, time: {} }],
+  })
+  editor.default.set("fastcrw") // make it active; set(false) disables
+})
+```
+
+- `execute` returns `{ url, title, content, time }[]`. Pass `signal` to `fetch`.
+- `await ctx.websearch.reload()` re-evaluates providers.
+
+## Config (`opencode.json`)
+
+```jsonc
+{
+  "plugins": [{ "package": "~/.config/opencode/plugins/fastcrw", "options": { "baseURL": "http://crw.home:3000", "limit": 8 } }],
+  "websearch": { "provider": "fastcrw" }
+}
+```
+
+- Key is plural `plugins` (v1: `plugin`). Entries are a string or `{ package, options }`.
+- `package` may be an npm name (`name`, `name@1.2.0`, `@scope/name`), `./local`, an absolute path or `file://`.
+- Auto-discovered: `.ts`/`.js` files and packages in `.opencode/plugins/` and `~/.config/opencode/plugins/`.
+- `websearch.provider` is a provider id or `"random"`; `"websearch": false` disables search. Built-in ids: exa, firecrawl, parallel, tavily, tinyfish.
+- CLI: `opencode plugin add|list|check|update|remove`.
+
+## Packaging (npm)
+
+`"type": "module"`, `exports["."]` pointing at the entry, dependency on `@opencode/plugin`.
+
+## Unverified: check at runtime, do not assume
+
+- Exact TypeScript types for the editor, `time` and `execute` args (read `@opencode/plugin` typings after install).
+- Inner shape of `time`, and whether extra result fields are allowed.
+- Precedence between config `websearch.provider` and `editor.default.set(id)`.