world-topology

The pure spatial math behind the coordinate-free MinSimApi surface (world-contract §8).

The contract's whole bet is that coordinates never cross the membrane — the driver (and a human) see topology + a qualitative distance ladder, never x/y/z. But the sim still keeps real geometry on its own side to compute those qualities. This module is that computation, factored out Babylon-free and deterministic so it can be unit-tested without a store or an engine — same discipline as fly-by-wire / formations / ballistics. The stateful WorldStore holds the place graph + sim-private positions and delegates the maths here.

Three pure functions, three jobs:

• proximityRung(distance, extent) — a real distance in, an adjective out. The ladder is the only spatial quantity that crosses the seam, and its bands scale with the place's extent: two metres is contact in an intimate closet and same-spot in a vast plain.
• routePortals(portals, from, to) — cheapest portal path between two places, so "how far to a place" is a graph fact (an errand's feasibility), not Vec3 maths. Skips locked portals — a locked door is not a feasible route until it opens.
• containmentPath(places, id) — the root→here breadcrumb up the parent chain, for the SchematicView's "where am I" path.

Example

import { proximityRung, routePortals } from 'tosijs-3d'
// proximityRung(1.8, 'small') → 'reach';  proximityRung(1.8, 'vast') → 'same-spot'
// routePortals(portals, 'study', 'garden') → { portals: ['door-1','gate-2'], cost: 45 } | null