Gates

resolveGateTransition is a pure state machine for abstract open/closed gates. The product supplies activation and occupancy after resolving its switches, links, power, pressure plates, or other sources.

Modes

• latch: activation opens a closed gate permanently. Loss of activation does not close it.
• automatic: activation opens the gate; loss of activation closes it only when the gate cell is unoccupied.

Transition table

Current	Active	Occupied	Mode	Result
closed	true	any	either	open / opened
closed	false	any	either	unchanged
open	true	any	either	unchanged
open	false	any	latch	unchanged
open	false	false	automatic	closed / closed
open	false	true	automatic	unchanged

Omitted occupied behaves as false. Occupancy protects only automatic closing; it does not prevent an active closed gate from opening.

const next = resolveGateTransition({
  mode: gate.mode,
  state: gate.state,
  active: linkedSources.some((source) => source.active),
  occupied: actors.some((actor) => sameCell(actor.at, gate.at)),
});

if (next.changed) {
  gate.state = next.state;
  events.push({ type: next.transition, gateId: gate.id });
}

Settlement integration

Gate activation often participates in a same-turn cycle: movement presses a switch, linked state updates, a gate opens, transport advances, then the switch changes again. Run transitions as explicit jobs or inside a bounded transport interlock, not through an unbounded global update loop.

Evaluate occupancy from committed authoritative state at the moment closing is considered. Animation position should never decide whether a gate can close.

Product responsibilities

The SDK does not define source lookup, AND/OR link logic, keys, locks, gate cells, crushing, pathfinding updates, sounds, or animation. It returns the next abstract state plus changed and a nullable transition so products can commit and present the result exactly once.

Zonoid example

Zonoid maps switches and powered plugs to two gate modes. A weighted switch or plug can latch a door open permanently, while an automatic door closes after its source turns off only when no actor occupies the doorway. The platform computes linked activation and occupancy, then uses this SDK transition to update the door and emit one opened or closed event.

Focused Zonoid demo board: a pressure plate opens the gate, the occupied doorway holds it open, and stepping clear lets it close safely.