[miniflare] Close WebSocket servers during dispose

.changeset/fix-close-websocket-servers-dispose.md

@@ -0,0 +1,7 @@
+---
+"miniflare": patch
+---
+
+Close WebSocket servers during dispose to prevent lingering connections
+
+The `#liveReloadServer` and `#webSocketServer` (both created with `noServer: true`) were never explicitly closed during `Miniflare.dispose()`. Connected WebSocket clients (e.g., browser live reload, devtools) would keep sockets alive, preventing the Node.js event loop from draining cleanly.

packages/miniflare/src/index.ts

@@ -3030,6 +3030,17 @@ export class Miniflare {
 			await this.#runtime?.dispose();
 
 			await this.#stopLoopbackServer();
+			// Terminate connected WebSocket clients and close the WebSocket servers.
+			// These are created with `noServer: true` so they aren't closed by
+			// stopping the loopback HTTP server.
+			for (const ws of this.#liveReloadServer.clients) {
+				ws.terminate();
+			}
+			this.#liveReloadServer.close();
+			for (const ws of this.#webSocketServer.clients) {
+				ws.terminate();
+			}
+			this.#webSocketServer.close();
 			// Best-effort cleanup: on Windows, workerd may not release file handles
 			// immediately after disposal, causing EBUSY errors. The temp directory
 			// lives in os.tmpdir() so the OS will clean it up eventually.