Auto-trigger locked-files restoration exactly at the 60s deadline

Previously the restore check only ran lazily on a player's next
message, so files could stay wrongly-removed for an arbitrary amount
of time after the window expired. The frontend now schedules a
setTimeout (using the server-provided deadline, mirroring the terminal
lock's reveal timer) that pings the backend right at the deadline so
the check runs promptly regardless of player activity. Restored via
data-files-removal-deadline on page load too, so a refresh mid-window
doesn't lose the timer.

assets/game1.js

@@ -177,6 +177,42 @@ function applyLock(lockData, apiEchoUrl, messageContainer) {
   }, 1000);
 }
 
+let filesRemovalTimer = null;
+let scheduledFilesRemovalDeadline = null;
+
+async function pingFilesRemovalDeadline(apiEchoUrl) {
+  if (!apiEchoUrl) return;
+  try {
+    // A no-op message is enough to make the server evaluate the deadline server-side;
+    // the actual restore notice (if any) arrives for everyone via the Mercure broadcast.
+    await fetchJson(apiEchoUrl, {
+      method: 'POST',
+      body: { message: '', ts: new Date().toISOString() },
+    });
+  } catch (e) {
+    console.error('[Game1] Failed to ping files-removal deadline:', e);
+  }
+}
+
+function scheduleFilesRemovalCheck(deadline, apiEchoUrl) {
+  if (!deadline || scheduledFilesRemovalDeadline === deadline) {
+    return; // nothing to (re)schedule
+  }
+  scheduledFilesRemovalDeadline = deadline;
+
+  if (filesRemovalTimer) {
+    clearTimeout(filesRemovalTimer);
+    filesRemovalTimer = null;
+  }
+
+  const delay = Math.max(0, deadline * 1000 - Date.now());
+  filesRemovalTimer = setTimeout(() => {
+    filesRemovalTimer = null;
+    scheduledFilesRemovalDeadline = null;
+    pingFilesRemovalDeadline(apiEchoUrl);
+  }, delay);
+}
+
 async function fetchJson(url, options = {}) {
   const opts = { ...options };
   const headers = new Headers(opts.headers || {});
@@ -236,6 +272,12 @@ document.addEventListener('DOMContentLoaded', async () => {
   const lockLockedAt = cfgEl.dataset.lockLockedAt;
   const lockRevealAt = cfgEl.dataset.lockRevealAt;
   const lockUnlockAt = cfgEl.dataset.lockUnlockAt;
+  const filesRemovalDeadline = cfgEl.dataset.filesRemovalDeadline;
+
+  // Resume the auto-restore timer after a page refresh, if a window is already running
+  if (filesRemovalDeadline) {
+    scheduleFilesRemovalCheck(parseInt(filesRemovalDeadline, 10), apiEchoUrl);
+  }
 
   if (mercurePublicUrl && topic) {
     subscribeToMercure(mercurePublicUrl, topic, screen);
@@ -391,6 +433,10 @@ document.addEventListener('DOMContentLoaded', async () => {
                     } else if (response.result.locked === false) {
                       clearLock();
                     }
+
+                    if (response.result.filesRemovalDeadline) {
+                      scheduleFilesRemovalCheck(response.result.filesRemovalDeadline, apiEchoUrl);
+                    }
                   }
                 } catch (err) {
                   console.error('[API][game1] Failed to send message:', err);