{
  "name": "fire_spreads_through_grass",
  "description": "Fire should spread through a line of grass",
  "seed": 42,
  "init_mode": "empty",
  "setup": [
    {"type": "fill_rect", "x": 100, "y": 115, "w": 20, "h": 1, "material": "stone"},
    {"type": "fill_rect", "x": 100, "y": 114, "w": 10, "h": 1, "material": "grass"},
    {"type": "set_cell", "x": 100, "y": 114, "material": "fire"}
  ],
  "steps": 30,
  "assertions": [
    {"type": "no_material_in_region", "x": 100, "y": 113, "w": 10, "h": 2, "material": "grass"}
  ]
}