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ditch McpUiHostInfoSchema in favour of ImplementationSchema

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This commit is contained in:
ochafik 2025-11-21 21:54:03 +00:00
commit 873075e690
5 changed files with 2 additions and 512 deletions
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209
app.ts
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@ -1,209 +0,0 @@
import {
type RequestOptions,
Protocol,
ProtocolOptions,
} from "@modelcontextprotocol/sdk/shared/protocol.js";
import {
CallToolRequest,
CallToolResult,
CallToolResultSchema,
Implementation,
LoggingMessageNotification,
Notification,
PingRequestSchema,
Request,
Result,
} from "@modelcontextprotocol/sdk/types.js";
import {
LATEST_PROTOCOL_VERSION,
McpUiAppCapabilities,
McpUiHostCapabilities,
McpUiHostInfo,
McpUiInitializedNotification,
McpUiInitializeRequest,
McpUiInitializeResultSchema,
McpUiMessageRequest,
McpUiMessageResultSchema,
McpUiOpenLinkRequest,
McpUiOpenLinkResultSchema,
McpUiSizeChangeNotification,
} from "./types";
import { Transport } from "@modelcontextprotocol/sdk/shared/transport.js";
export { PostMessageTransport } from "./message-transport.js";
export * from "./types";
type AppOptions = ProtocolOptions & {
autoResize?: boolean;
};
export class App extends Protocol<Request, Notification, Result> {
private _hostCapabilities?: McpUiHostCapabilities;
private _hostInfo?: McpUiHostInfo;
constructor(
private _appInfo: Implementation,
private _capabilities: McpUiAppCapabilities = {},
private options: AppOptions = { autoResize: true },
) {
super(options);
this.setRequestHandler(PingRequestSchema, (request) => {
console.log("Received ping:", request.params);
return {};
});
}
assertCapabilityForMethod(method: Request["method"]): void {
// TODO
}
assertRequestHandlerCapability(method: Request["method"]): void {
switch (method) {
case "tools/call":
case "tools/list":
if (!this._capabilities.tools) {
throw new Error(
`Client does not support tool capability (required for ${method})`,
);
}
return;
case "ping":
return;
default:
throw new Error(`No handler for method ${method} registered`);
}
}
assertNotificationCapability(method: Notification["method"]): void {
// TODO
}
async callServerTool(
params: CallToolRequest["params"],
options?: RequestOptions,
): Promise<CallToolResult> {
return await this.request(
{ method: "tools/call", params },
CallToolResultSchema,
options,
);
}
sendMessage(params: McpUiMessageRequest["params"], options?: RequestOptions) {
return this.request(
<McpUiMessageRequest>{
method: "ui/message",
params,
},
McpUiMessageResultSchema,
options,
);
}
sendLog(params: LoggingMessageNotification["params"]) {
return this.notification(<LoggingMessageNotification>{
method: "notifications/message",
params,
});
}
sendOpenLink(
params: McpUiOpenLinkRequest["params"],
options?: RequestOptions,
) {
return this.request(
<McpUiOpenLinkRequest>{
method: "ui/open-link",
params,
},
McpUiOpenLinkResultSchema,
options,
);
}
sendSizeChange(params: McpUiSizeChangeNotification["params"]) {
return this.notification(<McpUiSizeChangeNotification>{
method: "ui/notifications/size-change",
params,
});
}
setupSizeChangeNotifications() {
const sendBodySizeChange = () => {
let rafId: number | null = null;
// Debounce using requestAnimationFrame to avoid duplicate messages
// when both documentElement and body fire resize events
if (rafId !== null) {
cancelAnimationFrame(rafId);
}
rafId = requestAnimationFrame(() => {
const { body, documentElement: html } = document;
const bodyStyle = getComputedStyle(body);
const htmlStyle = getComputedStyle(html);
const width = body.scrollWidth;
const height =
body.scrollHeight +
(parseFloat(bodyStyle.borderTop) || 0) +
(parseFloat(bodyStyle.borderBottom) || 0) +
(parseFloat(htmlStyle.borderTop) || 0) +
(parseFloat(htmlStyle.borderBottom) || 0);
this.sendSizeChange({ width, height });
rafId = null;
});
};
sendBodySizeChange();
const resizeObserver = new ResizeObserver(sendBodySizeChange);
// Observe both html and body to catch all size changes
resizeObserver.observe(document.documentElement);
resizeObserver.observe(document.body);
return () => resizeObserver.disconnect();
}
override async connect(
transport: Transport,
options?: RequestOptions,
): Promise<void> {
await super.connect(transport);
try {
const result = await this.request(
<McpUiInitializeRequest>{
method: "ui/initialize",
params: {
appCapabilities: this._capabilities,
appInfo: this._appInfo,
protocolVersion: LATEST_PROTOCOL_VERSION,
},
},
McpUiInitializeResultSchema,
options,
);
if (result === undefined) {
throw new Error(`Server sent invalid initialize result: ${result}`);
}
this._hostCapabilities = result.hostCapabilities;
this._hostInfo = result.hostInfo;
await this.notification(<McpUiInitializedNotification>{
method: "ui/notifications/initialized",
});
if (this.options?.autoResize) {
this.setupSizeChangeNotifications();
}
} catch (error) {
// Disconnect if initialization fails.
void this.close();
throw error;
}
}
}

58
message-transport.ts
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@ -1,58 +0,0 @@
import {
JSONRPCMessage,
JSONRPCMessageSchema,
MessageExtraInfo,
} from "@modelcontextprotocol/sdk/types.js";
import type { RequestHandlerExtra } from "@modelcontextprotocol/sdk/shared/protocol.js";
import {
Transport,
TransportSendOptions,
} from "@modelcontextprotocol/sdk/shared/transport.js";
import { z } from "zod";
export class PostMessageTransport implements Transport {
private messageListener: (
this: Window,
ev: WindowEventMap["message"],
) => any | undefined;
constructor(
private eventTarget: Window = window.parent,
private eventSource?: MessageEventSource,
) {
this.messageListener = (event) => {
if (eventSource && event.source !== this.eventSource) {
console.error("Ignoring message from unknown source", event);
return;
}
const parsed = JSONRPCMessageSchema.safeParse(event.data);
if (parsed.success) {
console.info("[host] Parsed message", parsed.data);
this.onmessage?.(parsed.data);
} else {
console.error("Failed to parse message", parsed.error.message, event);
this.onerror?.(
new Error(
"Invalid JSON-RPC message received: " + parsed.error.message,
),
);
}
};
}
async start() {
window.addEventListener("message", this.messageListener);
}
async send(message: JSONRPCMessage, options?: TransportSendOptions) {
console.info("[host] Sending message", message);
this.eventTarget.postMessage(message, "*");
}
async close() {
window.removeEventListener("message", this.messageListener);
this.onclose?.();
}
onclose?: () => void;
onerror?: (error: Error) => void;
onmessage?: (message: JSONRPCMessage, extra?: MessageExtraInfo) => void;
sessionId?: string;
setProtocolVersion?: (version: string) => void;
}

3
src/app.ts
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@ -19,7 +19,6 @@ import {
LATEST_PROTOCOL_VERSION, LATEST_PROTOCOL_VERSION,
McpUiAppCapabilities, McpUiAppCapabilities,
McpUiHostCapabilities, McpUiHostCapabilities,
McpUiHostInfo,
McpUiInitializedNotification, McpUiInitializedNotification,
McpUiInitializeRequest, McpUiInitializeRequest,
McpUiInitializeResultSchema, McpUiInitializeResultSchema,
@ -40,7 +39,7 @@ type AppOptions = ProtocolOptions & {
export class App extends Protocol<Request, Notification, Result> { export class App extends Protocol<Request, Notification, Result> {
private _hostCapabilities?: McpUiHostCapabilities; private _hostCapabilities?: McpUiHostCapabilities;
private _hostInfo?: McpUiHostInfo; private _hostInfo?: Implementation;
constructor( constructor(
private _appInfo: Implementation, private _appInfo: Implementation,

8
src/types.ts
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@ -211,15 +211,9 @@ export type McpUiInitializeRequest = z.infer<
typeof McpUiInitializeRequestSchema typeof McpUiInitializeRequestSchema
>; >;
export const McpUiHostInfoSchema = z.object({
name: z.string(),
version: z.string(),
});
export type McpUiHostInfo = z.infer<typeof McpUiHostInfoSchema>;
export const McpUiInitializeResultSchema = z.object({ export const McpUiInitializeResultSchema = z.object({
protocolVersion: z.string(), protocolVersion: z.string(),
hostInfo: McpUiHostInfoSchema, hostInfo: ImplementationSchema,
hostCapabilities: McpUiHostCapabilitiesSchema, hostCapabilities: McpUiHostCapabilitiesSchema,
hostContext: McpUiHostContextSchema, hostContext: McpUiHostContextSchema,
}); });

236
types.ts
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@ -1,236 +0,0 @@
import {
CallToolResultSchema,
ContentBlockSchema,
EmptyResultSchema,
ImplementationSchema,
RequestId,
RequestIdSchema,
RequestSchema,
Tool,
ToolSchema,
} from "@modelcontextprotocol/sdk/types.js";
import { z } from "zod";
export const LATEST_PROTOCOL_VERSION = "2025-11-21";
export const McpUiOpenLinkRequestSchema = RequestSchema.extend({
method: z.literal("ui/open-link"),
params: z.object({
url: z.string().url(),
}),
});
export type McpUiOpenLinkRequest = z.infer<typeof McpUiOpenLinkRequestSchema>;
export const McpUiOpenLinkResultSchema = z.object({
isError: z.boolean(),
});
export type McpUiOpenLinkResult = z.infer<typeof McpUiOpenLinkResultSchema>;
export const McpUiMessageRequestSchema = RequestSchema.extend({
method: z.literal("ui/message"),
params: z.object({
role: z.literal("user"),
content: z.array(ContentBlockSchema),
}),
});
export type McpUiMessageRequest = z.infer<typeof McpUiMessageRequestSchema>;
export const McpUiMessageResultSchema = z.object({
// Note: we don't return the result from follow up messages as they might leak info from the chat.
// We do tell the caller if it errored, though.
isError: z.boolean(),
});
export type McpUiMessageResult = z.infer<typeof McpUiMessageResultSchema>;
// McpUiIframeReadyNotification removed - replaced by standard MCP initialization
// The SDK's oninitialized callback now handles the ready signal
export const McpUiSandboxProxyReadyNotificationSchema = z.object({
method: z.literal("ui/notifications/sandbox-proxy-ready"),
params: z.object({}),
});
export type McpUiSandboxProxyReadyNotification = z.infer<
typeof McpUiSandboxProxyReadyNotificationSchema
>;
export const McpUiSandboxResourceReadyNotificationSchema = z.object({
method: z.literal("ui/notifications/sandbox-resource-ready"),
params: z.object({
html: z.string(), //ReadResourceResultSchema,
sandbox: z.string().optional(),
}),
});
export type McpUiSandboxResourceReadyNotification = z.infer<
typeof McpUiSandboxResourceReadyNotificationSchema
>;
// Fired by the iframe when its body changes, and by the host when the viewport size changes.
export const McpUiSizeChangeNotificationSchema = z.object({
method: z.literal("ui/notifications/size-change"),
params: z.object({
width: z.number().optional(),
height: z.number().optional(),
}),
});
export type McpUiSizeChangeNotification = z.infer<
typeof McpUiSizeChangeNotificationSchema
>;
export const McpUiToolInputNotificationSchema = z.object({
method: z.literal("ui/notifications/tool-input"),
params: z.object({
arguments: z.record(z.unknown()).optional(),
}),
});
export type McpUiToolInputNotification = z.infer<
typeof McpUiToolInputNotificationSchema
>;
export const McpUiToolInputPartialNotificationSchema = z.object({
method: z.literal("ui/notifications/tool-input-partial"),
params: z.object({
arguments: z.record(z.unknown()).optional(),
}),
});
export type McpUiToolInputPartialNotification = z.infer<
typeof McpUiToolInputPartialNotificationSchema
>;
// Fired once both tool call returned *AND* host received ui/ui-lifecycle-iframe-ready.
export const McpUiToolResultNotificationSchema = z.object({
method: z.literal("ui/notifications/tool-result"),
params: CallToolResultSchema,
});
export type McpUiToolResultNotification = z.infer<
typeof McpUiToolResultNotificationSchema
>;
export const McpUiHostContextSchema = z.object({
toolInfo: z
.object({
// Metadata of the tool call that instantiated the App
id: RequestIdSchema, // JSON-RPC id of the tools/call request
tool: ToolSchema, // contains name, inputSchema, etc…
})
.optional(),
theme: z.enum(["light", "dark", "system"]).optional(),
displayMode: z.enum(["inline", "fullscreen", "pip", "carousel"]).optional(),
availableDisplayModes: z.array(z.string()).optional(),
viewport: z
.object({
width: z.number(),
height: z.number(),
maxHeight: z.number().optional(),
maxWidth: z.number().optional(),
})
.optional(),
locale: z.string().optional(), // BCP 47, e.g., "en-US"
timeZone: z.string().optional(), // IANA, e.g., "America/New_York"
userAgent: z.string().optional(),
platform: z.enum(["web", "desktop", "mobile"]).optional(),
deviceCapabilities: z
.object({
touch: z.boolean().optional(),
hover: z.boolean().optional(),
})
.optional(),
safeAreaInsets: z
.object({
top: z.number(),
right: z.number(),
bottom: z.number(),
left: z.number(),
})
.optional(),
});
export type McpUiHostContext = z.infer<typeof McpUiHostContextSchema>;
export const McpUiHostContextChangedNotificationSchema = z.object({
method: z.literal("ui/notifications/host-context-changed"),
params: McpUiHostContextSchema,
});
export type McpUiHostContextChangedNotification = z.infer<
typeof McpUiHostContextChangedNotificationSchema
>;
export const McpUiResourceTeardownRequestSchema = RequestSchema.extend({
method: z.literal("ui/resource-teardown"),
params: z.object({}),
});
export type McpUiResourceTeardownRequest = z.infer<
typeof McpUiResourceTeardownRequestSchema
>;
export const McpUiResourceTeardownResultSchema = EmptyResultSchema;
export type McpUiResourceTeardownResult = z.infer<
typeof McpUiResourceTeardownResultSchema
>;
export const McpUiHostCapabilitiesSchema = z.object({
experimental: z.object({}).optional(),
openLinks: z.object({}).optional(),
serverTools: z
.object({
listChanged: z.boolean().optional(),
})
.optional(),
serverResources: z
.object({
listChanged: z.boolean().optional(),
})
.optional(),
logging: z.object({}).optional(),
// TODO: elicitation, sampling...
});
export type McpUiHostCapabilities = z.infer<typeof McpUiHostCapabilitiesSchema>;
export const McpUiAppCapabilitiesSchema = z.object({
experimental: z.object({}).optional(),
// WebMCP-style tools exposed by the app to the host
tools: z
.object({
listChanged: z.boolean().optional(),
})
.optional(),
});
export type McpUiAppCapabilities = z.infer<typeof McpUiAppCapabilitiesSchema>;
export const McpUiInitializeRequestSchema = RequestSchema.extend({
method: z.literal("ui/initialize"),
params: z.object({
appInfo: ImplementationSchema,
appCapabilities: McpUiAppCapabilitiesSchema,
protocolVersion: z.string(),
}),
});
export type McpUiInitializeRequest = z.infer<
typeof McpUiInitializeRequestSchema
>;
export const McpUiHostInfoSchema = z.object({
name: z.string(),
version: z.string(),
});
export type McpUiHostInfo = z.infer<typeof McpUiHostInfoSchema>;
export const McpUiInitializeResultSchema = z.object({
protocolVersion: z.string(),
hostInfo: McpUiHostInfoSchema,
hostCapabilities: McpUiHostCapabilitiesSchema,
hostContext: McpUiHostContextSchema,
});
export type McpUiInitializeResult = z.infer<typeof McpUiInitializeResultSchema>;
export const McpUiInitializedNotificationSchema = z.object({
method: z.literal("ui/notifications/initialized"),
params: z.object({}),
});
export type McpUiInitializedNotification = z.infer<
typeof McpUiInitializedNotificationSchema
>;