Crate datagrout_panels_mcp 

Transpile Smart Panels into MCP Apps (SEP-1865) resources.

MCP Apps — the first official MCP extension, released 2026-01-26 — lets a server hand a host an interactive UI: an HTML document published as a ui:// resource with mime type text/html;profile=mcp-app, rendered in a sandboxed iframe that talks JSON-RPC to the host over postMessage. A tool links to its view through _meta.ui.resourceUri.

Why the two models line up

A Smart Panel is a declarative description of a view: kind, props, and a query that re-derives its rows. An MCP App is a document that receives its data by notification (ui/notifications/tool-result) rather than fetching it up front. So a panel transpiles cleanly: the panel’s kind and props become a static template, and the rows arrive at render time exactly as the extension already intends.

That means one panel definition, stored once as facts, can drive a native GUI (datagrout-panels-egui) and an MCP host — with no second authoring step and no divergence between the two.

Delivering rows

The host sends ui/notifications/tool-result. The document reads rows from structuredContent:

• a single panel: structuredContent.rows (or the whole structuredContent if it is an array);
• a dashboard: structuredContent.panels, an object keyed by child panel id, each value a rows array.

Where the panel comes from

Panels are published to DataGrout with the gateway’s smart_panel.publish tool and read back with smart_panel.list; that response becomes Panel values via datagrout_panels::Panel::all_from_list. A Panel built by hand transpiles identically, which is how the tests here run.

What this crate does and does not do

It emits documents and metadata. It does not serve them, register them, or speak MCP — a server does that with whatever MCP library it already uses. Keeping it a pure function of a Panel means it is testable without a host and embeddable in any server.

Structs

TranspileOptions

Transpiler options.

UiResource

A transpiled panel, ready to publish as an MCP resource.

Constants

MCP_APP_MIME

The only mime type the MCP Apps MVP supports.

UI_CAPABILITY

The capability key a host announces UI support under.

Functions

to_ui_resource

Transpile a panel into a ui:// resource.

tool_meta

The _meta a tool carries to link itself to a panel’s view.

ui_uri

Build the ui:// URI for a panel.