App: restart the server by itself when it stops, and a Try Again button on the error page

A server that had been up for a minute starts again without asking. One that
stops sooner shows the error page, now headed "Frame Control stopped", with a
Try Again button (the menu item was the only way, and hard to find).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

app/main.js

@@ -149,7 +149,7 @@ async function startServer() {
   const target = `http://127.0.0.1:${port}/`;
   for (let i = 0; i < 100; i++) {
     if (exited !== null) throw new Error(`The server exited (${exited}). See ${LOG}.`);
-    if (await ping(target)) { url = target; return; }
+    if (await ping(target)) { url = target; serverStarted = Date.now(); return; }
     await new Promise((r) => setTimeout(r, 100));
   }
   if (server === child) server = null;
@@ -175,18 +175,27 @@ function stopServer() {
   if (server) endServer(server);
 }
 
-function errorPage(message) {
+function errorPage(message, title = "Frame Control couldn't start") {
   const esc = (s) => s.replace(/[&<>]/g, (c) => ({ "&": "&amp;", "<": "&lt;", ">": "&gt;" }[c]));
   const html = `<!doctype html><meta charset="utf-8"><body style="margin:0;height:100vh;display:grid;
     place-items:center;background:${BG};color:#e6edf3;font:14px -apple-system,sans-serif">
-    <div style="max-width:560px;padding:32px;line-height:1.5"><h2>Frame Control couldn't start</h2>
-    <p>${esc(message)}</p><p style="color:#8b98a8">Fix it, then choose Frame → Restart Server.</p></div>`;
+    <div style="max-width:560px;padding:32px;line-height:1.5"><h2>${esc(title)}</h2>
+    <p>${esc(message)}</p>
+    <p><button onclick="this.disabled = true; frameApp.restartServer()" style="font:inherit;padding:6px 16px;
+      border-radius:6px;border:1px solid #30363d;background:#21262d;color:inherit;cursor:pointer">Try Again</button></p>
+    <p style="color:#8b98a8">Frame → Restart Server does the same.</p></div>`;
   return "data:text/html;charset=utf-8," + encodeURIComponent(html);
 }
 
+// A server that had been running starts again by itself (something stopped it: a
+// signal, a crash). One that stops again within a minute shows the error instead,
+// so a server that can't stay up doesn't restart forever.
+let serverStarted = 0;
 function serverDied(why) {
   url = null;
-  if (win) win.loadURL(errorPage(`The server stopped unexpectedly (${why}). See ${LOG}.`));
+  if (!win) return;
+  if (Date.now() - serverStarted > 60000) restartServer();
+  else win.loadURL(errorPage(`Its server stopped unexpectedly (${why}). See ${LOG}.`, "Frame Control stopped"));
 }
 
 // Restarts that overlap share one: two could each start a server, and the one
@@ -263,6 +272,8 @@ function fromUi(e) {
   } catch { return false; }
 }
 
+// The error page's Try Again button (there is no server page while it shows).
+ipcMain.handle("server:restart", (e) => { if (win && e.sender === win.webContents && !url) restartServer(); });
 ipcMain.handle("clipboard:read", (e) => fromUi(e) ? clipboard.readText() : "");
 ipcMain.handle("connection:setup", (e) => { if (fromUi(e)) setUpConnection(); });
 ipcMain.on("keys:capture", (e, on) => { if (fromUi(e)) win.webContents.setIgnoreMenuShortcuts(on === true); });

app/preload.js

@@ -13,6 +13,7 @@ contextBridge.exposeInMainWorld("frameApp", {
   notify: (message, request) => ipcRenderer.invoke("comfort:notify", message, request),
   readClipboard: () => ipcRenderer.invoke("clipboard:read"),
   setUpConnection: () => ipcRenderer.invoke("connection:setup"),
+  restartServer: () => ipcRenderer.invoke("server:restart"),  // the "couldn't start" page's Try Again
   // The Frame menu's headset switcher: the page tells it the headsets, and hears picks.
   devicesChanged: (list) => ipcRenderer.send("devices:changed", list),
   onUseDevice: (cb) => {