decoder reconnect

tests/browser_fake_decoder.js

@@ -21,7 +21,9 @@ export async function startFakeDecoder() {
   // 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();
+  let totalConnections = 0;
   server.on("upgrade", (req, socket) => {
+    totalConnections += 1;
     sockets.add(socket);
     socket.on("close", () => sockets.delete(socket));
     const key = req.headers["sec-websocket-key"];
@@ -32,6 +34,12 @@ export async function startFakeDecoder() {
   await new Promise((resolve, reject) => { server.once("error", reject); server.listen(port, "127.0.0.1", resolve); });
   return {
     port,
+    activeConnections: () => sockets.size,
+    totalConnections: () => totalConnections,
+    // Drops every currently-open socket with a raw TCP reset (not a clean WS close
+    // handshake) to simulate a decoder/network interruption, while the server keeps
+    // listening so the frontend's own reconnect logic has somewhere to reconnect to.
+    dropConnections: () => { for (const socket of sockets) socket.destroy(); },
     close: () => new Promise(resolve => {
       for (const socket of sockets) socket.destroy();
       server.close(() => resolve());