Initial commit

src/message-transport.ts

@@ -0,0 +1,58 @@
+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;
+}