{
  "_doc": "Seam regions. SIM: an extractor extracts only while its footprint overlaps a seam rect (boolean this round; `richness` is forward-looking for when extraction rate goes data-driven). RENDER: `era` skins the ground. `resource` is the codex-correct payload of that stratum (advisory — SIM's rule is presence, not resource-gating). Grid is -32..31 on both axes; rect is {x,y,w,h} in tiles, origin = min corner. `relicReserve` is the SE quiet corner kept seam-free so SIM's seed-derived relic (18-28 from origin, never on a seam) always has somewhere to land.",
  "relicReserve": { "x": 12, "y": 12, "w": 20, "h": 20 },
  "seams": [
    { "id": "stream-crust-west", "era": "stream", "resource": "mdat-ore",
      "rect": { "x": -31, "y": -5, "w": 4, "h": 12 }, "richness": 0.6 },
    { "id": "stream-crust-east", "era": "stream", "resource": "mdat-ore",
      "rect": { "x": 8, "y": -4, "w": 6, "h": 8 }, "richness": 0.5 },
    { "id": "disc-mantle-vein", "era": "disc", "resource": "bayer-grit",
      "rect": { "x": -6, "y": -14, "w": 10, "h": 6 }, "richness": 0.85 },
    { "id": "broadcast-shelf-south", "era": "broadcast", "resource": "field-splinters",
      "rect": { "x": -14, "y": 16, "w": 12, "h": 6 }, "richness": 0.55 },
    { "id": "reel-beds-deep", "era": "reel", "resource": "silver-frames",
      "rect": { "x": -30, "y": -24, "w": 10, "h": 6 }, "richness": 0.5 },

    { "id": "hidden-nitrate-vein", "era": "reel", "resource": "silver-frames",
      "rect": { "x": 21, "y": -25, "w": 1, "h": 1 }, "richness": 1.0, "hidden": true },
    { "id": "hidden-rainbow-pit", "era": "disc", "resource": "bayer-grit",
      "rect": { "x": -25, "y": 25, "w": 1, "h": 1 }, "richness": 1.0, "hidden": true },
    { "id": "hidden-payload-lode", "era": "stream", "resource": "mdat-ore",
      "rect": { "x": 27, "y": 7, "w": 1, "h": 1 }, "richness": 1.0, "hidden": true }
  ]
}