Official Plugin — Markdown

fan.summer.markdown is the simpler of the two shipped official plugins. It is a split-pane Markdown editor whose only backend capability is server-side rendering to HTML via commonmark. It declares no permissions and no AI tools — a minimal, canonical example of the plugin contract.

What it does

• Renders a Vuetify split-pane editor: Markdown source on the left, live HTML preview on the right.
• On every edit, the UI calls the worker's render method, which parses the Markdown server-side with commonmark and returns HTML.
• The rendering happens out-of-process in the worker — the host never parses Markdown itself.

The manifest

{
  "schemaVersion": 2,
  "id": "fan.summer.markdown",
  "name": "Markdown Editor",
  "description": "Split-pane Markdown editor with isolated server-side rendering",
  "version": "4.0.0",
  "author": "FengYu",
  "icon": "language-markdown",
  "category": "text",
  "ui": { "entry": "ui/index.html" },
  "backend": { "callTimeoutSeconds": 30 },
  "permissions": [],
  "homepage": "https://github.com/MuskStark/FengYu",
  "official": true,
  "rpc": {
    "methods": {
      "render": {
        "description": "Render Markdown source to sanitized HTML via commonmark (server-side).",
        "inputSchema": {
          "type": "object",
          "properties": {
            "markdown": { "type": "string", "description": "The Markdown source to render." }
          },
          "required": ["markdown"]
        },
        "outputSchema": {
          "type": "object",
          "properties": {
            "success": { "type": "boolean" },
            "summary": { "type": "string" },
            "html": { "type": "string", "nullable": true, "description": "The rendered, sanitized HTML." }
          },
          "required": ["success", "summary"]
        }
      }
    }
  },
  "aiTools": []
}

Key points:

• category: "text" — a text editing / rendering plugin.
• permissions: [] — it never touches the filesystem; no file I/O grants.
• aiTools: [] — supportsAi is false; it is a pure UI tool, not callable from chat.
• backend.callTimeoutSeconds: 30 — the host spawns the shaded jar and drives it over JSON-RPC on stdio.

See Manifest for every field.

The render action

MarkdownWorkerMain registers a single JSON-RPC method: render.

new JsonRpcWorker().method(
        PluginMethods.RENDER, RenderInput.class, RenderOutput.class,
        (RenderInput input, RpcContext ctx) -> plugin.render(input, ctx)).run()

The UI invokes it on every keystroke (debounced):

import { createPluginRpc } from './generated/fengyu-rpc'
const rpc = createPluginRpc(fengyu)
const { html } = await rpc.render({ markdown: source })

Method	Params	Returns
render	{ markdown: string }	{ success: true, html: string } — commonmark-rendered HTML

Because there is no file I/O and no AI surface, this is the entire backend contract: one method in, one HTML string out. See Worker (JSON-RPC) for the protocol.

The UI

The UI is a Vuetify split-pane MF:

• Left pane — a Markdown source editor (<v-textarea> or equivalent).
• Right pane — the live HTML preview, repainted from each render result.
• Built with its iframe-local @infinia/plugin-ui Vuetify instance (MD3), bound to host theme and locale changes through the SDK environment bridge.

It loads in the sandboxed iframe under /plugin-runtime/fan.summer.markdown/** and bridges to the host through @infinia/plugin-sdk. See UI Micro-frontend.

Next steps

• Manifest — the full schema reference.
• Worker (JSON-RPC) — the render registration pattern.
• Official Plugin — Excel — the more complex sibling with permissions, file I/O, and six AI tools.