fix obs popup issues

tests/browser_fake_decoder.js

@@ -0,0 +1,40 @@
+import { createHash } from "node:crypto";
+import { createServer } from "node:http";
+import { createServer as createNetServer } from "node:net";
+
+export async function freePort() {
+  const server = createNetServer();
+  await new Promise((resolve, reject) => { server.once("error", reject); server.listen(0, "127.0.0.1", resolve); });
+  const port = server.address().port;
+  await new Promise(resolve => server.close(resolve));
+  return port;
+}
+
+// Accepts the WebSocket upgrade handshake so the frontend's real decoder-connect path
+// (src/decoder_runtime.js) reaches `connected: true` without a physical AMMC decoder.
+// No frames are sent or parsed: scenarios using this only need an established socket,
+// not lap data.
+export async function startFakeDecoder() {
+  const port = await freePort();
+  const server = createServer();
+  // The upgraded sockets are intentionally left open (no decoder frames needed), so a
+  // plain server.close() would wait forever for them to end; track and destroy them
+  // explicitly instead. closeAllConnections() does not reach upgraded sockets.
+  const sockets = new Set();
+  server.on("upgrade", (req, socket) => {
+    sockets.add(socket);
+    socket.on("close", () => sockets.delete(socket));
+    const key = req.headers["sec-websocket-key"];
+    if (!key) { socket.destroy(); return; }
+    const accept = createHash("sha1").update(key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11").digest("base64");
+    socket.write(["HTTP/1.1 101 Switching Protocols", "Upgrade: websocket", "Connection: Upgrade", `Sec-WebSocket-Accept: ${accept}`, "", ""].join("\r\n"));
+  });
+  await new Promise((resolve, reject) => { server.once("error", reject); server.listen(port, "127.0.0.1", resolve); });
+  return {
+    port,
+    close: () => new Promise(resolve => {
+      for (const socket of sockets) socket.destroy();
+      server.close(() => resolve());
+    }),
+  };
+}