Authoring levers

A world you can play is three agreements that must not be converted into each other. Salt Road, the felt harbour, is the worked example. Turn one lever, export, and look. Turning two at once is how a person ends up drawn in a room the simulation says they are not in.

The three grids

Grid	Unit	Where you edit it	Does the simulation hash it?
Occupancy	zone id	zones, entityPlacements, entry gates	Yes. This is who is where, and whether the door opened.
Cartesian	gridX / gridY, tile 32, then ×3 at 48 in the sandbox	the editor canvas and the Godot .tscn	No.
Dimetric	256×128 diamond, span 3	WorldProject.presentation	No. The stage draws this and never sends it back.

scaleForSandbox multiplies cartesian geometry and skips presentation by name. A cell in presentation is copied, not computed from gridX / gridY.

Levers, and the repo that hears them

You want	Lever	Heard by
Another room	a zone, its neighbours, its prose	engine, joined to a scene node by zone id
A door that explains itself	entryGate conditions, hard or soft, and reason	engine refuses; stage only displays the reason
A person in a room	entityPlacements[].zoneId	engine. Hashed.
Where that person stands on the diamond	presentation.occupancy[].cell and facing	stage. Not hashed. Must sit inside that zone’s span box, and the zone must match the placement.
Wet stone, dirt, dry stone	presentation.floor plate id (stone_wet, stone_a, dirt_a, dirt_b)	stage atlas. Absent floor still wets the long quay.
The anchor of a zone on the map	presentation.zoneCells	stage.
A thing in someone’s inventory	engine itemPlacements of { itemId, entityId }	engine. A zone-standing prop is not this. The guild seal on the counting-house floor is a stage marker, not a give-item.
What the player hears	cue id on the felt payload, file assets/felt/<cueId>.wav in the stage	stage mixer. Missing file is a sine stand-in. The cue id is never hashed.

presentation is not a field on the engine ContentPack. The stage fixture writes it onto pack.json. The sidecar file keeps only the keys engine 3.12.0 loads.

Salt Road, one change at a time

The authored world is dogfood/worlds/salt-road.ts. Export both lanes from one command:

npx tsx dogfood/export-stage-fixture.ts \
  --world=salt-road \
  --out=<ai-rpg-stage>/fixtures \
  --doctor \
  --strict \
  --engine-out=dogfood/output/salt-road/pack.json

--strict refuses to write when a presentation advisory fires (a cell outside its zone, a person drawn in the wrong room, no player row). The scene it writes is a join graph: zone nodes and gate text, and no play pawn. A full Godot project export still emits CharacterBody2D and world_data; the stage project cannot instance those paths.

Play from the stage checkout with node tools/play.mjs. The sidecar is TCP --listen, with fixtures/salt-road.manifest.json beside the engine pack.

Where the rest of the book is

• Types and the eight presentation advisories: Schema & Types.
• What the Godot exporter keeps, approximates, and drops: Godot Export.
• What the engine actually loads: Engine Export.
• How the client draws a lever you already set: the stage handbook’s authoring levers, and the engine’s Visual Clients.