{
  "kind": "building",
  "id": "rainchain-cistern",
  "role": "rainwater-harvester",
  "name": "Rainchain Cistern",
  "footprint": "1.75×2.25 tiles",
  "function": "A one-worker cistern coaxes moisture from vapour gardens, catches it in a roof basin, and stores rainwater for homes and workshops.",
  "shape_and_silhouette": "A tall narrow collecting vault steps down from an elevated catch basin to a round rear tank, with an unmistakable descending curtain of rain cups along one side.",
  "visual_description": "Rough pearl cloudstone encloses a deep blue-ice-lined tank, the +Z face has a compact oval service door beneath a projecting eave, both long sides expose graduated hammered-copper cup chains, the rear carries a blue-ice sluice gate and wheel, and low pumice buttresses anchor the wet mass.",
  "production_notes": "This rain-working type descends from old shelf-edge water stores, so its masonry is heavy and patched while its ice lining and polished cup lips show constant specialist care.",
  "departure": "Its vertical chain curtain and rear circular tank distinguish it from the low domestic basins and the radial machinery of the other weather works.",
  "shared_traits": [
    "Wind-rounded cloudstone masonry around a buoyant pumice frame.",
    "Copper fittings, vapour rope, and visible bands of repaired prism glass.",
    "Deep openings and a stable silhouette shaped for exposed cloud shelves."
  ],
  "constraints": [
    "The main entrance faces +Z below the collecting eave.",
    "Resolve the open basin interior, tank rear, sluice channel, chain cups, wheel, and all support feet.",
    "Use stacked basins, cylinders, rigid cup links, and stepped channels rather than fluid or freeform geometry."
  ],
  "idle_animation": "Copper cups make a gentle sequential tip down the chain as droplets pass toward the tank, and the sluice wheel occasionally rocks a few degrees.",
  "day_night": "By day the blue-ice lining reads clear teal, while at night stored water gives the basin and sluice a cool internal glow."
}