Use websocket /message endpoint to deliver reload request

packages/vscode-extension/src/project/metro.ts

@@ -267,28 +267,35 @@ export class Metro implements Disposable {
     return initPromise;
   }
 
-  public async reload() {
-    const appReady = this.devtools.appReady();
-    await fetch(`http://localhost:${this._port}/reload`);
-    await appReady;
-  }
-
-  public async openDevMenu() {
-    // to send request to open dev menu, we route it through metro process
-    // that maintains a websocket connection with the device. Specifically,
-    // /message endpoint is used to send messages to the device, and metro proxies
-    // messages between different clients connected to that endpoint.
-    // Therefore, to send the message to the device we:
-    // 1. connect to the /message endpoint over websocket
-    // 2. send specifically formatted message to open dev menu
+  private async sendMessageToDevice(message: "devMenu" | "reload") {
+    // we use metro's /message websocket endpoint to deliver specifically formatted
+    // messages to the device.
+    // Metro implements a websocket proxy that proxies messages between connected
+    // clients. This is a mechanism used by the CLI to deliver messages for things
+    // like reload or open dev menu.
+    // The message format is a JSON object with a "method" field that specifies
+    // the action, and version field with the protocol version (currently 2).
     const ws = new WebSocket(`ws://localhost:${this._port}/message`);
     await new Promise((resolve) => ws.addEventListener("open", resolve));
     ws.send(
-      JSON.stringify({ version: 2 /* protocol version, needs to be set to 2 */, method: "devMenu" })
+      JSON.stringify({
+        version: 2 /* protocol version, needs to be set to 2 */,
+        method: message,
+      })
     );
+    // we disconnect immediately after sending the message as there's no need
+    // to keep the connection open since we use it on rare occations.
     ws.close();
   }
 
+  public async reload() {
+    await this.sendMessageToDevice("reload");
+  }
+
+  public async openDevMenu() {
+    await this.sendMessageToDevice("devMenu");
+  }
+
   public async getDebuggerURL() {
     const WAIT_FOR_DEBUGGER_TIMEOUT_MS = 15_000;