The crafts, or nobody is given a blueprint
A building's shape comes out of a small network that is bred, not written, and what the building is, hut, granary, palisade, bridge, is read back off the finished shape by measuring what it physically affords.
There is not a blueprint in the codebase. A craft is a lineage of builders, one per kind of need: shelter, keeping, making, defence, husbandry, winning material, assembly, crossing. Each is two learned things and nothing else: a population of small networks, sixteen numbers in describing the situation (how badly the city wants this, how rich it is, what age, how easily it can get timber, stone, clay and metal, the plot, the slope, the water, the middle, the wall, the woodland, the fear) and twenty out, which are the decisions that make a building; and a reward model of what the lineage currently believes each thing a building affords is worth.
Affordances are physical and measured off the finished shape: volume that is walled, covered and can be got into; volume that also stays dry; floor with daylight on it; open ground held inside a fence; worked soil; a line of standing mass with nothing inside it; a deck over open water; what it cost. A building’s capacity is never assigned. A granary holds what its dry volume holds, and if you build it badly it holds less.
The population learns by rehearsal spread across simulation days, thousands of generations of apprentices a century, and the year’s accounts tell them what any of it was worth. Once a shape has been named, the trade moves in with its furniture: an oven and a flue for the forge, a wheel for the mill, a hoist beam over the warehouse door, a bell on the school, a fire in any house with a stack to take the smoke. Those are elements, not plans, and the shape is measured again with them in.
The consequence is the thing worth watching: small shelters first, then keeping things dry, which wants a lifted floor and no windows, and the same lifted floor on piers, once the crossing craft needs it, is a bridge. The templates are a third way between the crafts and the voxel editor, for when you want to say what a house should look like.
In the code: crates/sim/src/craft/mod.rs crates/sim/src/craft/design.rs crates/sim/src/craft/form.rs crates/sim/src/craft/afford.rs