feat: preserve solo runs across production restarts

test/monsterCollision.test.js

@@ -8,6 +8,7 @@
  */
 
 const Game = require('../src/game/game');
+const DungeonGenerator = require('../src/game/dungeon');
 
 function openGame() {
   // Default-size dungeon so the digger generates validly; we then override the map and
@@ -23,6 +24,37 @@ function openGame() {
 }
 
 describe('Monster collision with multi-step movement', () => {
+  test('two-room fallback spawns the monster deterministically on a distant passable tile', () => {
+    const FL = "'1";
+    const map = Array.from({ length: 7 }, (_, y) => Array.from({ length: 7 }, (_, x) =>
+      (x === 0 || y === 0 || x === 6 || y === 6) ? '#' : FL));
+    const dungeon = {
+      map,
+      rooms: [],
+      entrance: [1, 1],
+      exit: [5, 5],
+      treasure: [4, 4],
+      torches: []
+    };
+    const generatedFingerprint = DungeonGenerator.layoutFingerprint(dungeon);
+    const generate = jest.spyOn(DungeonGenerator, 'generate').mockReturnValue(dungeon);
+    const previousLevels = process.env.DUNGEON_LEVELS;
+    process.env.DUNGEON_LEVELS = '1';
+    try {
+      const game = new Game('fallback-spawn', { id: 1 }, { width: 7, height: 7, cryptoType: 'XMR' });
+      expect(game.monster.getState()).toMatchObject({ x: 5, y: 4 });
+      expect(game.dungeon.map[game.monster.y][game.monster.x]).toBe(FL);
+      expect(game.monster.isAt(game.player.x, game.player.y)).toBe(false);
+      expect(game.monster.isAt(game.dungeon.exit[0], game.dungeon.exit[1])).toBe(false);
+      expect(game.monster.isAt(game.dungeon.treasure[0], game.dungeon.treasure[1])).toBe(false);
+      expect(DungeonGenerator.layoutFingerprint(game.dungeon)).toBe(generatedFingerprint);
+    } finally {
+      generate.mockRestore();
+      if (previousLevels === undefined) delete process.env.DUNGEON_LEVELS;
+      else process.env.DUNGEON_LEVELS = previousLevels;
+    }
+  });
+
   test('2-step monster adjacent to the player catches it (no phasing through)', () => {
     const game = openGame();
     game.difficultyConfig.monster.movesPerPlayerMove = 2;