v0.9.1 web ui fixes and improvements

internal/server/webserver/chess-client-web/app.js

@@ -5,7 +5,8 @@ let gameState = {
     turn: 'w',
     isPlayerWhite: true,
     isLocked: false,
-    pollInterval: null,
+    polling: false,
+    pollController: null,
     apiUrl: '',
     selectedSquare: null,
     healthCheckInterval: null,
@@ -672,41 +673,64 @@ async function triggerComputerMove() {
 }
 
 function startPolling() {
-    gameState.pollInterval = setInterval(async () => {
+    gameState.polling = true;
-        try {
+    pollOnce();
-            const response = await fetch(`${gameState.apiUrl}/api/v1/games/${gameState.gameId}`);
-            if (!response.ok) {
-                const errorInfo = handleApiError('poll game state', null, response);
-                if (response.status === 404) {
-                    stopPolling();
-                    unlockBoard();
-                    flashErrorMessage('Game no longer exists');
-                    gameState.gameId = null;
-                    return;
-                }
-                // Non-404: already displayed by handleApiError above, keep polling
-                return;
-            }
-
-            const game = await response.json();
-            if (game.state !== 'pending') {
-                stopPolling();
-                updateGameDisplay(game);
-                unlockBoard();
-            }
-            gameState.networkError = false;
-            updateServerIndicator('healthy');
-        } catch (error) {
-            handleApiError('poll game state', error);
-            stopPolling();
-            unlockBoard();
-        }
-    }, 1500);
 }
 
 function stopPolling() {
-    clearInterval(gameState.pollInterval);
+    gameState.polling = false;
-    gameState.pollInterval = null;
+    if (gameState.pollController) {
+        gameState.pollController.abort();
+        gameState.pollController = null;
+    }
+}
+
+async function pollOnce() {
+    if (!gameState.polling || !gameState.gameId) return;
+
+    const moveCount = (gameState.moveList || []).length;
+    gameState.pollController = new AbortController();
+
+    try {
+        const response = await fetch(
+            `${gameState.apiUrl}/api/v1/games/${gameState.gameId}?wait=true&moveCount=${moveCount}`,
+            { signal: gameState.pollController.signal }
+        );
+
+        if (!gameState.polling) return;
+
+        if (!response.ok) {
+            const errorInfo = handleApiError('poll game state', null, response);
+            if (response.status === 404) {
+                stopPolling();
+                unlockBoard();
+                flashErrorMessage('Game no longer exists');
+                gameState.gameId = null;
+                return;
+            }
+            // Retry after delay for transient errors
+            setTimeout(pollOnce, 2000);
+            return;
+        }
+
+        const game = await response.json();
+        gameState.networkError = false;
+        updateServerIndicator('healthy');
+
+        if (game.state !== 'pending') {
+            stopPolling();
+            updateGameDisplay(game);
+            unlockBoard();
+        } else {
+            // Still pending, long-poll again
+            pollOnce();
+        }
+    } catch (error) {
+        if (error.name === 'AbortError') return;
+        handleApiError('poll game state', error);
+        stopPolling();
+        unlockBoard();
+    }
 }
 
 function lockBoard() {