What happened
The Gateway River Crossing, straight three-cell variant with seam version 1, went through the full acceptance loop on the test bench: load in the prefab editor, walk the deck, read every seam against the standard, then drive a vanilla truck across the whole tile in both directions.
It passed. The tile is tagged in source control and treated as frozen from here.
What was proven
- The approach ramps hold the smoothness spec: seven blocks of rise over fifty-six of run, so a vehicle never bottoms out or launches.
- The terrain surface under the span stays continuous, the way the game’s own bridges do it. Swapping the layer below the road instead of cutting a hole is what finally made the seam hold.
- Authored water in the basin survives world generation and renders as water.
What broke on the way
Earlier variants failed for three different reasons: floating debris left behind by generated ramps, a reader mask in our own tooling that hid a block the game rejected, and a scratch analysis that re-implemented the prefab reader with an off-by-one index and returned convincing values at the wrong coordinates. Each one became a rule in the standard.
Next target
Diamond Interchange V2 is packaged and passes every static gate, but it has never been driven. That drive is next.