fix: poll concurrency guard, room code retry, join race, domino draw debounce

Phase 1.6: add pollInFlight guard to match-session.js so overlapping polls
are skipped when server is slow.

Phase 2.5: room code generation retries up to 5 times on collision.

Phase 2.6: join_room uses service key, checks if room is full, prevents
double-join, and auto-starts when player count is met.

Phase 3.1: dealAndSyncToServer retries on failure with toast notification.

Phase 3.3: drawFromBoneyard syncs once after all tiles drawn instead of
firing N parallel requests.

Phase 3.6: check-invites uses PostgREST cs filter on JSONB players array
instead of scanning all waiting matches.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

api/friends.php

@@ -450,9 +450,10 @@ if ($method === 'POST') {
             }
         }
 
-        // Check domino_matches table
+        // Check domino_matches table (filter by player at DB level)
         $dominoInvites = $sdb->get('domino_matches', [
             'status' => 'eq.waiting',
+            'players' => 'cs.["' . $userId . '"]',
             'select' => 'id,players,game_state,created_at',
             'order' => 'created_at.desc',
             'limit' => 5
@@ -479,9 +480,10 @@ if ($method === 'POST') {
             }
         }
 
-        // Check ludo_matches table
+        // Check ludo_matches table (filter by player at DB level)
         $ludoInvites = $sdb->get('ludo_matches', [
             'status' => 'eq.waiting',
+            'players' => 'cs.["' . $userId . '"]',
             'select' => 'id,players,game_state,created_at',
             'order' => 'created_at.desc',
             'limit' => 5

api/multiplayer.php

@@ -18,27 +18,44 @@ switch ($action) {
     case 'create_room':
         $db = supabase($token);
         $table = $gameKey === 'domino' ? 'domino_matches' : 'ludo_matches';
+        $result = null;
+        $code = '';
+        for ($attempt = 0; $attempt < 5; $attempt++) {
             $code = strtoupper(substr(bin2hex(random_bytes(3)), 0, 6));
+            $existing = $db->get($table, ['room_code' => 'eq.' . $code, 'status' => 'eq.waiting', 'limit' => 1]);
+            if (!empty($existing) && !isset($existing['error'])) continue;
             $result = $db->insert($table, [
                 'room_code' => $code,
                 'status' => 'waiting',
                 'players' => json_encode([$userId]),
                 'created_by' => $userId
             ]);
+            break;
+        }
+        if (!$result) jsonError('Failed to generate unique room code', 500);
         jsonResponse(['room_code' => $code, 'match' => $result[0] ?? $result]);
         break;
 
     case 'join_room':
         $roomCode = $input['room_code'] ?? '';
         if (!$roomCode) jsonError('room_code required');
-        $db = supabase($token);
+        $sdb = supabaseService();
         $table = $gameKey === 'domino' ? 'domino_matches' : 'ludo_matches';
-        $match = $db->getOne($table, ['room_code' => 'eq.' . $roomCode, 'status' => 'eq.waiting']);
-        if (!$match) jsonError('Room not found', 404);
+        $match = $sdb->get($table, ['room_code' => 'eq.' . $roomCode, 'status' => 'eq.waiting', 'select' => 'id,players,player_count', 'limit' => 1]);
+        if (!is_array($match) || empty($match) || isset($match['error'])) jsonError('Room not found', 404);
+        $match = $match[0];
+
+        $players = is_array($match['players']) ? $match['players'] : json_decode($match['players'] ?? '[]', true);
+        if (in_array($userId, $players)) {
+            jsonResponse(['success' => true, 'match_id' => $match['id']]);
+            break;
+        }
+        $maxPlayers = $match['player_count'] ?? ($gameKey === 'domino' ? 2 : 4);
+        if (count($players) >= $maxPlayers) jsonError('Room is full', 409);
 
-        $players = json_decode($match['players'] ?? '[]', true);
         $players[] = $userId;
-        $db->update($table, ['players' => json_encode($players)], ['id' => 'eq.' . $match['id']]);
+        $newStatus = count($players) >= $maxPlayers ? 'in_progress' : 'waiting';
+        $sdb->update($table, ['players' => $players, 'status' => $newStatus], ['id' => 'eq.' . $match['id']]);
         jsonResponse(['success' => true, 'match_id' => $match['id']]);
         break;
 

public/js/core/match-session.js

@@ -60,6 +60,7 @@ export function destroy() {
   }
   localStorage.removeItem('el3ab_active_match');
   currentSession = null;
+  pollInFlight = false;
 }
 
 // Check if player has an active match to resume (after tab refresh)
@@ -88,12 +89,16 @@ export function markOpponentActive() {
 }
 
 // ===== POLLING =====
+let pollInFlight = false;
+
 function startPolling() {
   if (!currentSession) return;
   currentSession.pollTimer = setInterval(async () => {
     if (!currentSession || !currentSession.isActive) return;
-    if (currentSession.isBackground) return; // Don't poll when tab is hidden
+    if (currentSession.isBackground) return;
+    if (pollInFlight) return;
 
+    pollInFlight = true;
     try {
       const endpoint = currentSession.gameType === 'ludo' ? 'ludo-match.php' : currentSession.gameType === 'domino' ? 'domino-match.php' : currentSession.gameType === 'backgammon' ? 'backgammon-match.php' : 'game.php';
       const data = await net.post(endpoint, {
@@ -103,25 +108,23 @@ function startPolling() {
 
       if (!data || data.error) return;
 
-      // Connection is alive
       const wasDisconnected = (Date.now() - currentSession.lastServerPing) > 10000;
       currentSession.lastServerPing = Date.now();
       if (wasDisconnected) currentSession.onConnectionRestored?.();
 
-      // Handle server-detected abandonment
       if (data.status === 'abandoned') {
         currentSession.onOpponentAbandon?.();
         return;
       }
 
-      // Notify about opponent's move (includes _turn_timed_out flags)
       currentSession.onOpponentMove?.(data);
 
     } catch (e) {
-      // Network error
       if (Date.now() - currentSession.lastServerPing > 10000) {
         currentSession.onConnectionLost?.();
       }
+    } finally {
+      pollInFlight = false;
     }
   }, POLL_INTERVAL);
 }

public/js/modules/domino/scenes/game.js

@@ -392,7 +392,11 @@ async function dealAndSyncToServer(el, matchId) {
         dealt: true,
       })
     });
-  } catch (e) {}
+  } catch (e) {
+    console.error('[domino] deal sync failed:', e);
+    bus.emit('toast', { text: 'Sync error — retrying...', duration: 2000 });
+    setTimeout(() => dealAndSyncToServer(el, matchId), 2000);
+  }
 }
 
 async function fetchOpponentProfile(el) {
@@ -840,12 +844,12 @@ async function drawFromBoneyard(el) {
     state.hands[state.myPlayerIndex].push(tile);
     audio.play('click');
     juice.hapticLight?.();
-    syncDrawToServer();
     updateUI(el);
     refreshHand();
     await new Promise(r => setTimeout(r, 400));
   }
 
+  syncDrawToServer();
   state.drawing = false;
 
   if (!rules.hasValidMove(state.hands[state.myPlayerIndex], state.leftEnd, state.rightEnd) && state.boneyard.length === 0) {