Build/buy interactions in our own UI (currently via the drawer)
Per-structure bespoke models, replacing category defaults over time
Tech-stack sign-off — see docs/DECISIONS.md
Your call
The architecture question is written up as ADR-001 in docs/DECISIONS.md,
with three options and a recommendation. Session 1 built on the recommended one
(engine untouched, graphics on top) because it was the only one that could be proven
cheaply — but it is reversible, and nothing is committed until you weigh in.
Drop notes anywhere in docs/IDEAS.md; that file is yours.