refactor: harden loto game per code review

- Validate localStorage shape on load (typed parse, guarded set)
- Fix isRowComplete to require at least one number per row
- Split row-scan effect into bingo + waiting passes so updates to
  later rows are not skipped by an early return
- Memoize per-row completeness; was recomputing 81 times per render
- Replace clickable divs with real <button>s; aria-label, aria-pressed,
  focus ring, dialog role + escape on the bingo modal
- Freeze the master tracking board to make module-scope state safer
- Allow NEXT_BASE_PATH to override the prod default for forks /
  custom-domain deploys

app/loto-game-logic.ts

@@ -76,44 +76,88 @@ export function generateGrid(): number[][] {
   return cell;
 }
 
+function safeParse<T>(raw: string | null, validate: (v: unknown) => v is T): T | null {
+  if (!raw) return null;
+  try {
+    const parsed = JSON.parse(raw) as unknown;
+    return validate(parsed) ? parsed : null;
+  } catch {
+    return null;
+  }
+}
+
+function isNumberMatrix(v: unknown): v is number[][] {
+  return (
+    Array.isArray(v) &&
+    v.length === NUM_ROWS &&
+    v.every(
+      (row) =>
+        Array.isArray(row) &&
+        row.length === NUM_COLS &&
+        row.every((n) => typeof n === "number")
+    )
+  );
+}
+
+function isBoolMatrix(v: unknown): v is boolean[][] {
+  return (
+    Array.isArray(v) &&
+    v.length === NUM_ROWS &&
+    v.every(
+      (row) =>
+        Array.isArray(row) &&
+        row.length === NUM_COLS &&
+        row.every((b) => typeof b === "boolean")
+    )
+  );
+}
+
 export function saveGrid(grid: number[][], prefix = "loto"): void {
-  localStorage.setItem(`${prefix}_grid`, JSON.stringify(grid));
+  try {
+    localStorage.setItem(`${prefix}_grid`, JSON.stringify(grid));
+  } catch {
+    // localStorage disabled or quota exceeded — ignore, app still works in-memory
+  }
 }
 
 export function loadGrid(prefix = "loto"): number[][] | null {
-  const data = localStorage.getItem(`${prefix}_grid`);
-  if (!data) return null;
   try {
-    return JSON.parse(data);
+    return safeParse(localStorage.getItem(`${prefix}_grid`), isNumberMatrix);
   } catch {
     return null;
   }
 }
 
 export function saveCrossedState(crossed: boolean[][], prefix = "loto"): void {
-  localStorage.setItem(`${prefix}_crossed`, JSON.stringify(crossed));
+  try {
+    localStorage.setItem(`${prefix}_crossed`, JSON.stringify(crossed));
+  } catch {
+    // see saveGrid
+  }
 }
 
 export function loadCrossedState(prefix = "loto"): boolean[][] | null {
-  const data = localStorage.getItem(`${prefix}_crossed`);
-  if (!data) return null;
   try {
-    return JSON.parse(data);
+    return safeParse(localStorage.getItem(`${prefix}_crossed`), isBoolMatrix);
   } catch {
     return null;
   }
 }
 
-/** Check if a row has all its numbers crossed */
+/** Check if a row has all its numbers crossed (and has at least one number) */
 export function isRowComplete(
   grid: number[][],
   crossed: boolean[][],
   row: number
 ): boolean {
-  for (let col = 0; col < 9; col++) {
-    if (grid[row][col] > 0 && !crossed[row]?.[col]) return false;
+  let hasNumber = false;
+  for (let col = 0; col < NUM_COLS; col++) {
+    if (grid[row][col] > 0) {
+      hasNumber = true;
+      if (!crossed[row]?.[col]) return false;
+    }
   }
-  return true;
+  return hasNumber;
 }
 
 /** Find the single remaining uncrossed number in a row, or null if != 1 remaining */
@@ -123,7 +167,7 @@ export function getWaitingNumber(
   row: number
 ): number | null {
   let remaining: number | null = null;
-  for (let col = 0; col < 9; col++) {
+  for (let col = 0; col < NUM_COLS; col++) {
     if (grid[row][col] > 0 && !crossed[row]?.[col]) {
       if (remaining !== null) return null;
       remaining = grid[row][col];

app/loto-player-board.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useCallback, useEffect, useRef, useState } from "react";
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import {
   generateGrid,
   getWaitingNumber,
@@ -72,30 +72,36 @@ export default function PlayerBoard({ storagePrefix = "loto" }: PlayerBoardProps
   useEffect(() => {
     if (!grid || crossed.length === 0) return;
 
+    // Pass 1: at most one bingo popup per render
     for (let i = 0; i < grid.length; i++) {
       if (!celebratedRows.current.has(i) && isRowComplete(grid, crossed, i)) {
         celebratedRows.current.add(i);
         notifiedWaitingRows.current.add(i);
         setCongratsRow(i + 1);
         setShowCongrats(true);
-        return;
+        break;
       }
+    }
+
+    // Pass 2: update waiting state for every non-celebrated row
+    for (let i = 0; i < grid.length; i++) {
+      if (celebratedRows.current.has(i)) continue;
       const waitNum = getWaitingNumber(grid, crossed, i);
       if (waitNum !== null && !notifiedWaitingRows.current.has(i)) {
         notifiedWaitingRows.current.add(i);
         showToast(`Chờ ${waitNum}`);
-        return;
-      }
-      if (
-        waitNum === null &&
-        notifiedWaitingRows.current.has(i) &&
-        !celebratedRows.current.has(i)
-      ) {
+      } else if (waitNum === null && notifiedWaitingRows.current.has(i)) {
         notifiedWaitingRows.current.delete(i);
       }
     }
   }, [grid, crossed, showToast]);
 
+  // Precompute per-row completeness so we don't call isRowComplete 81×/render
+  const rowCompleteness = useMemo(() => {
+    if (!grid || crossed.length === 0) return [];
+    return grid.map((_, row) => isRowComplete(grid, crossed, row));
+  }, [grid, crossed]);
+
   const handleGenerate = useCallback(() => {
     if (grid && !confirm("Bạn có muốn tạo lại bảng không?")) return;
     const newGrid = generateGrid();
@@ -133,40 +139,52 @@ export default function PlayerBoard({ storagePrefix = "loto" }: PlayerBoardProps
 
       {grid ? (
         <div className="relative">
-          <div className="rounded-2xl overflow-hidden shadow-xl shadow-slate-200/50 dark:shadow-black/30 border border-slate-200 dark:border-slate-700">
+          <div
+            aria-label="Bảng lô tô"
+            className="rounded-2xl overflow-hidden shadow-xl shadow-slate-200/50 dark:shadow-black/30 border border-slate-200 dark:border-slate-700"
+          >
             <div className="loto-grid">
               {grid.flat().map((num, idx) => {
                 const row = Math.floor(idx / 9);
                 const col = idx % 9;
                 const hasNumber = num > 0;
-                const isCrossed = hasNumber && crossed[row]?.[col];
-                const rowComplete =
-                  hasNumber && isRowComplete(grid, crossed, row);
+                const isCrossed = hasNumber && !!crossed[row]?.[col];
+                const rowComplete = hasNumber && rowCompleteness[row];
+
+                if (!hasNumber) {
+                  return (
+                    <div
+                      key={idx}
+                      aria-hidden="true"
+                      className="relative flex items-center justify-center aspect-square border-r border-b border-slate-200/80 dark:border-slate-700/60 bg-slate-50 dark:bg-slate-900/60"
+                    />
+                  );
+                }
 
                 return (
-                  <div
+                  <button
                     key={idx}
-                    onClick={
-                      hasNumber ? () => handleCellClick(row, col) : undefined
-                    }
+                    type="button"
+                    aria-label={`Số ${num}${isCrossed ? ", đã đánh dấu" : ""}`}
+                    aria-pressed={isCrossed}
+                    onClick={() => handleCellClick(row, col)}
                     className={`
                       relative flex items-center justify-center
                       aspect-square text-base sm:text-xl font-bold
                       border-r border-b border-slate-200/80 dark:border-slate-700/60
-                      transition-all select-none
+                      transition-all select-none cursor-pointer
+                      focus:outline-none focus:ring-2 focus:ring-inset focus:ring-indigo-400
                       ${
-                        hasNumber
-                          ? isCrossed
-                            ? rowComplete
-                              ? "cell-crossed bg-emerald-100 dark:bg-emerald-900/40 text-emerald-500 dark:text-emerald-400 cursor-pointer"
-                              : "cell-crossed bg-red-50 dark:bg-red-950/30 text-red-400 dark:text-red-500 cursor-pointer"
-                            : "bg-white dark:bg-slate-800 text-slate-800 dark:text-slate-100 cursor-pointer hover:bg-indigo-50 dark:hover:bg-indigo-950/30 hover:text-indigo-600 dark:hover:text-indigo-400"
-                          : "bg-slate-50 dark:bg-slate-900/60"
+                        isCrossed
+                          ? rowComplete
+                            ? "cell-crossed bg-emerald-100 dark:bg-emerald-900/40 text-emerald-500 dark:text-emerald-400"
+                            : "cell-crossed bg-red-50 dark:bg-red-950/30 text-red-400 dark:text-red-500"
+                          : "bg-white dark:bg-slate-800 text-slate-800 dark:text-slate-100 hover:bg-indigo-50 dark:hover:bg-indigo-950/30 hover:text-indigo-600 dark:hover:text-indigo-400"
                       }
                     `}
                   >
-                    {hasNumber ? num : ""}
-                  </div>
+                    {num}
+                  </button>
                 );
               })}
             </div>
@@ -174,6 +192,8 @@ export default function PlayerBoard({ storagePrefix = "loto" }: PlayerBoardProps
 
           {toast && (
             <div
+              role="status"
+              aria-live="polite"
               onClick={dismissToast}
               className="absolute inset-0 flex items-center justify-center pointer-events-auto cursor-pointer z-10"
             >
@@ -191,8 +211,15 @@ export default function PlayerBoard({ storagePrefix = "loto" }: PlayerBoardProps
 
       {showCongrats && (
         <div
+          role="dialog"
+          aria-modal="true"
+          aria-labelledby="congrats-title"
           className="fixed inset-0 z-50 flex items-center justify-center bg-black/50 backdrop-blur-sm animate-fade-in"
           onClick={() => setShowCongrats(false)}
+          onKeyDown={(e) => {
+            if (e.key === "Escape") setShowCongrats(false);
+          }}
+          tabIndex={-1}
         >
           <div
             className="relative mx-4 max-w-sm w-full rounded-3xl bg-white dark:bg-slate-800 p-8 text-center shadow-2xl animate-pop-in"
@@ -208,7 +235,10 @@ export default function PlayerBoard({ storagePrefix = "loto" }: PlayerBoardProps
               🎊
             </div>
 
-            <h2 className="mt-6 text-3xl font-black bg-gradient-to-r from-amber-500 via-pink-500 to-purple-500 bg-clip-text text-transparent">
+            <h2
+              id="congrats-title"
+              className="mt-6 text-3xl font-black bg-gradient-to-r from-amber-500 via-pink-500 to-purple-500 bg-clip-text text-transparent"
+            >
               Kinh!
             </h2>
             <p className="mt-3 text-lg text-slate-600 dark:text-slate-300">

app/master/page.tsx

@@ -58,7 +58,10 @@ function loadState(): MasterState | null {
   }
 }
 
-const BOARD = buildBoard();
+const BOARD: ReadonlyArray<ReadonlyArray<number>> = Object.freeze(
+  buildBoard().map((row) => Object.freeze(row))
+);
+const BOARD_FLAT: ReadonlyArray<number> = Object.freeze(BOARD.flatMap((r) => r));
 
 export default function MasterPage() {
   const [state, setState] = useState<MasterState | null>(null);
@@ -179,9 +182,12 @@ export default function MasterPage() {
 
         {/* Master board 9x10 */}
         {state ? (
-          <div className="rounded-2xl overflow-hidden shadow-xl shadow-slate-200/50 dark:shadow-black/30 border border-slate-200 dark:border-slate-700">
+          <div
+            aria-label="Bảng theo dõi số đã xổ"
+            className="rounded-2xl overflow-hidden shadow-xl shadow-slate-200/50 dark:shadow-black/30 border border-slate-200 dark:border-slate-700"
+          >
             <div className="master-grid">
-              {BOARD.flat().map((num, idx) => {
+              {BOARD_FLAT.map((num, idx) => {
                 const hasNumber = num > 0;
                 const isCalled = hasNumber && calledSet.has(num);
 

next-env.d.ts

@@ -1,6 +1,6 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
-import "./.next/dev/types/routes.d.ts";
+import "./.next/types/routes.d.ts";
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/app/api-reference/config/typescript for more information.

next.config.ts

@@ -20,7 +20,9 @@ function codeserverConfig() {
 }
 
 const cs = isCodeserver ? codeserverConfig() : null;
-const basePath = cs?.basePath ?? (isProd ? "/loto" : "");
+// NEXT_BASE_PATH wins so custom-domain / fork deploys don't have to edit code.
+const basePath =
+  process.env.NEXT_BASE_PATH ?? cs?.basePath ?? (isProd ? "/loto" : "");
 
 const nextConfig: NextConfig = {
   output: "export",