feat: implement startingLevel option and remove INITIAL_FPS constant

- Remove INITIAL_FPS constant entirely - no longer exists
- Add startingLevel to GameOptions (defaults to 1)
- FPS now equals currentLevel (1:1 ratio)
- Points per food always equals currentLevel
- Game can start at any level with appropriate speed/scoring

src/types.ts

@@ -32,6 +32,7 @@ export type GameOptions = {
   cols: number;
   rows: number;
   timeLimit?: number;
+  startingLevel?: number;
 };
 
 // ============================================================================

src/useGame/useGame.ts

@@ -10,6 +10,7 @@ import { useScore } from "../useScore";
 export function useGame(optionsOrCols: GameOptions | number, rows?: number, platformHook?: unknown): GameManager {
   // Support both old signature (cols, rows) and new signature (options)
   let cols: number;
+  let startingLevel: number | undefined;
   let actualPlatformHook = platformHook;
 
   if (typeof optionsOrCols === 'object') {
@@ -17,6 +18,7 @@ export function useGame(optionsOrCols: GameOptions | number, rows?: number, plat
     const options = optionsOrCols as GameOptions;
     cols = options.cols;
     rows = options.rows;
+    startingLevel = options.startingLevel;
     actualPlatformHook = rows as unknown as typeof platformHook;
   } else {
     // Old signature: useGame(cols, rows, platformHook)
@@ -32,7 +34,7 @@ export function useGame(optionsOrCols: GameOptions | number, rows?: number, plat
 
   const foodManager = useFood(cols, rows, boardManager);
 
-  const gameManager = useGameStatus(boardManager, snakeManager, foodManager);
+  const gameManager = useGameStatus(boardManager, snakeManager, foodManager, { startingLevel });
   const { gameStatus, setGameStatus, startGame, quitGame, togglePause, score, level } = gameManager;
 
   useEffect(() => {

src/useGameStatus/useGameStatus.ts

@@ -4,28 +4,32 @@ import type { UseBoardType } from "../useBoard";
 import type { UseCursorType } from "../useCursor";
 import type { UseFoodType } from "../useGame/useFood";
 
-const INITIAL_FPS = 3;
 const FOODS_PER_LEVEL = 2;
 
+export type UseGameStatusParams = {
+  startingLevel?: number;
+};
+
 export function useGameStatus(
   boardManager: UseBoardType,
   snakeManager: UseCursorType,
-  foodManager: UseFoodType
+  foodManager: UseFoodType,
+  params?: UseGameStatusParams
 ) {
+  const startingLevel = params?.startingLevel ?? 1;
   const { containerRef } = boardManager;
   const { initSnake, clearSnake, snakeBodyRef } = snakeManager;
   const { spawnFood, clearFood } = foodManager;
   const [gameStatus, setGameStatus] = useState<GameStatus>("waiting");
   const [score, setScore] = useState(0);
-  const [level, setLevel] = useState(1);
+  const [level, setLevel] = useState(startingLevel);
   const [paused, setPaused] = useState(false);
-  const levelRef = useRef(1);
+  const levelRef = useRef(startingLevel);
   const foodsEatenRef = useRef(0);
   const gameLoopRef = useRef<number | null>(null);
   const lastUpdateRef = useRef<number>(0);
   const snakeManagerRef = useRef(snakeManager);
   const foodManagerRef = useRef(foodManager);
-  const currentFpsRef = useRef(INITIAL_FPS);
 
   snakeManagerRef.current = snakeManager;
   foodManagerRef.current = foodManager;
@@ -34,10 +38,9 @@ export function useGameStatus(
     initSnake();
     spawnFood(snakeBodyRef.current, 3);
     setScore(0);
-    setLevel(1);
+    setLevel(startingLevel);
-    levelRef.current = 1;
+    levelRef.current = startingLevel;
     foodsEatenRef.current = 0;
-    currentFpsRef.current = INITIAL_FPS;
     setGameStatus("started");
   };
 
@@ -62,7 +65,7 @@ export function useGameStatus(
       lastUpdateRef.current = performance.now();
 
        const gameLoop = (timestamp: number) => {
-        const msPerFrame = 1000 / currentFpsRef.current;
+         const msPerFrame = 1000 / levelRef.current;
          const elapsed = timestamp - lastUpdateRef.current;
 
          if (elapsed >= msPerFrame) {
@@ -100,7 +103,6 @@ export function useGameStatus(
                  const newLevel = levelRef.current + 1;
                  levelRef.current = newLevel;
                  setLevel(newLevel);
-                currentFpsRef.current = INITIAL_FPS + (newLevel - 1);
                  foodsEatenRef.current = 0;
                }