Base Scaffold System

@@ -17,3 +17,23 @@ Scaffold System, read the page: If the page still carries any `🔶 FILL-IN` item, treat it as unknown — do not invent values; name the section owner (James/Luke for mechanical, Caleb for the control panel) instead.++## Stacking: every machine pin into a machine contact, on every layer++A layout stacks base scaffold -> user scaffold -> molecule. Two rules hold on every layer (John, 2026-10-06):++1. **X/Y:** each machine pin sits over a machine contact of the layer below.+   - The base scaffold's large contacts are at 16 + 32 n mm (18 x 18). A user scaffold's corner large pins and a+     large-pin molecule's pins land on them.+   - A LrgMed user scaffold's medium contacts are at FL + 4 + 8 k mm from its FL pin: an 8 mm pitch offset 4 mm,+     not every 4 mm. Read them from its page's circuit.json (`pcb_plated_hole`, 0.78 mm drill). A medium-pin+     molecule's FL pin goes on one, and its pin span must be a multiple of 8 mm.+2. **Z:** each board rests on the layer below, on the contacts' rims. It is never sunk into the lower board, and+   never floating so high that its pins (medium short 4.95 mm below their board, large short 10.34 mm) miss the+   contacts. A scaffold GLB's origin is its board's mid-plane, so a layout z of 0 sinks it half a board thickness+   into the base. Stacking "8.4 mm per level" sets the next board on the pin heads, with its pins in the air.++`adom-aiflow-probing stack` checks both from the real data (the base grid, the scaffold page's circuit.json, the+molecule's footprint JSON, the GLBs' own bounds) and names the exact position that fixes each problem.+`stack --fix` writes them into the layout. Look at a corner pin of each layer from the side in the twin (a pup+window or a Hydrogen webview) to confirm.