The cup board asked for itself and got the gore board

The GET filter spelled its modes out as a literal `[^gzc]` character class, so
`?m=u` sanitised to nothing, fell back to 'g', and the server answered the cup
board's request with the gore board — which the client then printed in the cup
board's words: 7121 kills as LEAGUE 7121. The filter is derived from MODES now,
where the mode list has lived all along.

And the client checks the answer it got: the response names the board it is,
so a server that does not know a board (an old one, mid-deploy) makes the
screen say THIS BOARD IS NOT UP YET instead of mislabelling another board's
rows. Nothing beats something wrong on a leaderboard.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

server.py

@@ -320,8 +320,12 @@ class Handler(SimpleHTTPRequestHandler):
         if path == '/ws':
             return self.handle_ws()
         if path == '/api/scores':
-            want = re.sub(r'[^gzc]', '', (self.path.split('m=')[1].split('&')[0]
-                                          if 'm=' in self.path else ''))[:1] or 'g'
+            # DERIVED FROM MODES, never spelled out again (2026-08-31): this filter was a literal
+            # `[^gzc]` character class, so the day the cup board was added the server answered its
+            # requests with the GORE board — and the client printed 7121 kills as "LEAGUE 7121".
+            want = (self.path.split('m=')[1].split('&')[0] if 'm=' in self.path else '')[:1]
+            if want not in MODES:
+                want = 'g'                   # an unknown board is the default one, never a new one
             with lock:
                 return self.reply(200, {'m': want,
                                         'scores': public([r for r in load() if mode_of(r) == want])})

src/stats.js

@@ -220,7 +220,13 @@ export function lastRun() { const r = last; last = null; return r; }
 export async function board(mode = MODE_GORE) {
   const r = await fetch(API + 'scores?m=' + mode, { cache: 'no-store' });
   if (!r.ok) throw new Error('board ' + r.status);
-  return (await r.json()).scores || [];
+  const d = await r.json();
+  // THE SERVER NAMES THE BOARD IT ANSWERED WITH, and we check it (2026-08-31): a server that does
+  // not know a board falls back to the default one, and rendering those rows here prints one
+  // board's currency in another's words — gore kills as LEAGUE 7121, which is exactly what a
+  // stale server did the day the cup board shipped. Nothing is better than something wrong.
+  if (d.m && d.m !== mode) { const e = new Error('board not up'); e.absent = true; throw e; }
+  return d.scores || [];
 }
 
 // The SAME normalisation server.py's clean() applies. Both ends have to agree or nothing lines up:
@@ -331,7 +337,11 @@ export async function drawRanks(rows, mode = MODE_GORE) {
   if (!rows) {
     el.innerHTML = '<p class="none">READING THE BOARD…</p>';
     try { rows = await board(mode); }
-    catch { el.innerHTML = '<p class="none">THE BOARD IS UNREACHABLE.</p>'; return; }
+    catch (e) {
+      el.innerHTML = `<p class="none">${e && e.absent ? 'THIS BOARD IS NOT UP YET.'
+                                                      : 'THE BOARD IS UNREACHABLE.'}</p>`;
+      return;
+    }
   }
   if (!rows.length) { el.innerHTML = '<p class="none">NOBODY IS ON THIS BOARD YET. BE FIRST.</p>'; return; }
   const me = savedName();