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,
@@ -672,9 +673,32 @@ async function triggerComputerMove() {
 }
 
 function startPolling() {
-    gameState.pollInterval = setInterval(async () => {
+    gameState.polling = true;
+    pollOnce();
+}
+
+function stopPolling() {
+    gameState.polling = false;
+    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}`);
+        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) {
@@ -684,29 +708,29 @@ function startPolling() {
                 gameState.gameId = null;
                 return;
             }
-                // Non-404: already displayed by handleApiError above, keep polling
+            // 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();
         }
-            gameState.networkError = false;
-            updateServerIndicator('healthy');
     } catch (error) {
+        if (error.name === 'AbortError') return;
         handleApiError('poll game state', error);
         stopPolling();
         unlockBoard();
     }
-    }, 1500);
-}
-
-function stopPolling() {
-    clearInterval(gameState.pollInterval);
-    gameState.pollInterval = null;
 }
 
 function lockBoard() {