(
    output: "merged",
    nodes: [
        ( id: "load",   kind: LoadMesh,       path: "models/mech.glb" ),
        ( id: "vol",    kind: SpherePacking,  radius: 0.010, radius_min: 0.003, count: 80000, relax_iters: 0, seed: 42 ),
        ( id: "surf",   kind: SurfaceScatter, density: 1200.0, seed: 7 ),
        ( id: "tv",     kind: GroupTag,       tag: 1 ),
        ( id: "ts",     kind: GroupTag,       tag: 2 ),
        ( id: "merged", kind: Merge ),
    ],
    edges: [
        ( ("load",  "geo"),    ("vol",    "geo") ),
        ( ("load",  "geo"),    ("surf",   "geo") ),
        ( ("vol",   "points"), ("tv",     "points") ),
        ( ("surf",  "points"), ("ts",     "points") ),
        ( ("tv",    "points"), ("merged", "points") ),
        ( ("ts",    "points"), ("merged", "points") ),
    ],
)