fix: enforce echo puzzle constraints and validate maps

index.html

@@ -371,6 +371,7 @@
 
     const STORAGE_KEY = 'echo-loop-progress-v1';
     const MAX_PULSES = 120;
+    const MAX_ECHOES = 4;
     const DIRS = Object.freeze({
       up: { dx: 0, dy: -1, key: 'U', label: '上' },
       left: { dx: -1, dy: 0, key: 'L', label: '左' },
@@ -416,12 +417,8 @@
         map: [
           '###############',
           '#S..aA........#',
-          '#.###.#####.#.#',
-          '#...#.....#...#',
-          '###.#.###.#.#.#',
-          '#b..#...B...G.#',
-          '#.###########.#',
-          '#.............#',
+          '#######.#######',
+          '#b......B..G..#',
           '###############'
         ]
       },
@@ -535,8 +532,7 @@
       const active = new Set();
       Object.entries(state.plates).forEach(([code, point]) => {
         const occupiedByEcho = state.echoes.some((echo) => echo.x === point.x && echo.y === point.y);
-        const occupiedByPlayer = state.player.x === point.x && state.player.y === point.y;
-        if (occupiedByEcho || occupiedByPlayer) active.add(code);
+        if (occupiedByEcho) active.add(code);
       });
       return active;
     }
@@ -611,6 +607,15 @@
         showToast('还没有可封存的路线');
         return;
       }
+      if (state.echoes.length >= MAX_ECHOES) {
+        showToast('记忆库已满 · 先用现有回声完成实验');
+        return;
+      }
+      const currentPlate = tileAt(state.player.x, state.player.y);
+      if (!isPlate(currentPlate)) {
+        showToast('只有站在绿色节点上，才能封存回声');
+        return;
+      }
       const echoNumber = state.echoes.length + 1;
       state.echoes.push({ id: echoNumber, x: state.start.x, y: state.start.y, actions: [...state.actions] });
       resetEchoPositions();
@@ -753,7 +758,7 @@
           els.echoList.appendChild(entry);
         });
       }
-      els.bankCount.textContent = `${String(state.echoes.length).padStart(2, '0')} / 04`;
+      els.bankCount.textContent = `${String(state.echoes.length).padStart(2, '0')} / ${String(MAX_ECHOES).padStart(2, '0')}`;
       els.echoCoord.textContent = state.echoes.length ? `${state.echoes.length} 条记忆正在从起点重播` : '尚未封存任何记忆';
       els.echoStatus.textContent = state.echoes.length ? '在线' : '空';
       els.echoStatus.className = `objective-status${state.echoes.length ? ' live' : ''}`;