proper anchor invalidation

src/useBoard/useMazeNavigation.ts

@@ -26,35 +26,43 @@ export function useMazeNavigation(maze: MazeCell[][]): MazeNavigator {
      if (direction === 'left' || direction === 'right') {
        const step = direction === 'left' ? -1 : 1;
        let cc = c;
-      let lastValidPos = { row: r, col: c };
 
        while (true) {
          const next = cc + step;
-        if (next < 0 || next >= colsCount) break;
-        if (maze[r][next].includes('wall')) break;
-        if (!maze[r][next].includes('wall')) {
-          lastValidPos = { row: r, col: next };
+         if (next < 0 || next >= colsCount) return null;
+         if (maze[r][next].includes('wall')) {
+           const wallIdx = next;
+           const expectedWallIdx = direction === 'left' ? 0 : colsCount - 1;
+           const expectedCellIdx = direction === 'left' ? 1 : colsCount - 2;
+
+           if (wallIdx !== expectedWallIdx) return null;
+           if (cc !== expectedCellIdx) return null;
+           if (cc === c) return null;
+
+           return { row: r, col: cc };
          }
          cc = next;
        }
-
-      return lastValidPos.col !== c ? lastValidPos : null;
      } else {
        const step = direction === 'top' ? -1 : 1;
        let rr = r;
-      let lastValidPos = { row: r, col: c };
 
        while (true) {
          const next = rr + step;
-        if (next < 0 || next >= rowsCount) break;
-        if (maze[next][c].includes('wall')) break;
-        if (!maze[next][c].includes('wall')) {
-          lastValidPos = { row: next, col: c };
+         if (next < 0 || next >= rowsCount) return null;
+         if (maze[next][c].includes('wall')) {
+           const wallIdx = next;
+           const expectedWallIdx = direction === 'top' ? 0 : rowsCount - 1;
+           const expectedCellIdx = direction === 'top' ? 1 : rowsCount - 2;
+
+           if (wallIdx !== expectedWallIdx) return null;
+           if (rr !== expectedCellIdx) return null;
+           if (rr === r) return null;
+
+           return { row: rr, col: c };
          }
          rr = next;
        }
-
-      return lastValidPos.row !== r ? lastValidPos : null;
      }
    }
 

src/useCursor/useCursor.ts

@@ -5,6 +5,25 @@ import { useGameKeys } from './useGameKeys';
 import { useMazeNavigation } from '../useBoard';
 import { useVimMotions } from './useVimMotions';
 
+function validateAnchorMove(direction: 'start' | 'end' | 'top' | 'bottom', currentPos: Coord, board: BoardManager): boolean {
+  const navDirection = direction === 'start' ? 'left' :
+    direction === 'end' ? 'right' :
+      direction === 'top' ? 'top' : 'bottom';
+
+  const navigator = useMazeNavigation(board.mazeRef.current);
+  const target = navigator.findAnchorTarget(currentPos, navDirection);
+  
+  if (!target) return false;
+
+  const dr = target.row > currentPos.row ? 1 :
+    target.row < currentPos.row ? -1 : 0;
+  const dc = target.col > currentPos.col ? 1 :
+    target.col < currentPos.col ? -1 : 0;
+  const steps = Math.abs(target.row - currentPos.row) + Math.abs(target.col - currentPos.col);
+
+  return navigator.validatePath(currentPos, { row: dr, col: dc }, steps);
+}
+
 export function useCursor(board: BoardManager, gameStatusManager: GameStatusManager) {
   const position = useRef<Coord>({ row: 0, col: 0 })
   const mode = useRef<CursorMode>('normal')
@@ -66,10 +85,7 @@ export function useCursor(board: BoardManager, gameStatusManager: GameStatusMana
          target === 'top' ? 'top' : 'bottom';
 
      const anchorTarget = navigator.findAnchorTarget(currentPos, direction);
-    if (!anchorTarget) {
-      window.dispatchEvent(new Event("maze-invalid"));
-      return;
-    }
+     if (!anchorTarget) return;
 
      const dr = anchorTarget.row > currentPos.row ? 1 :
        anchorTarget.row < currentPos.row ? -1 : 0;
@@ -87,18 +103,34 @@ export function useCursor(board: BoardManager, gameStatusManager: GameStatusMana
    }
 
    function moveToStart(): void {
+     if (!validateAnchorMove('start', position.current, board)) {
+       window.dispatchEvent(new Event("maze-invalid"));
+       return;
+     }
      moveToAnchor('start');
    }
 
    function moveToEnd(): void {
+     if (!validateAnchorMove('end', position.current, board)) {
+       window.dispatchEvent(new Event("maze-invalid"));
+       return;
+     }
      moveToAnchor('end');
    }
 
    function moveToTop(): void {
+     if (!validateAnchorMove('top', position.current, board)) {
+       window.dispatchEvent(new Event("maze-invalid"));
+       return;
+     }
      moveToAnchor('top');
    }
 
    function moveToBottom(): void {
+     if (!validateAnchorMove('bottom', position.current, board)) {
+       window.dispatchEvent(new Event("maze-invalid"));
+       return;
+     }
      moveToAnchor('bottom');
    }