MDietermann
f1b85862da
Measured while building #16: at 10 000 enemies the grid rebuild costs 0.057 ms against 0.021 ms for move_enemies — 2.7x more, not less. ADR-0004 §3 counted arithmetic and missed what dominates: move_enemies is a linear table walk, the rebuild writes into ~7000 scattered buckets. The decision does not change. It never rested on the comparison but on the absolute bound of 0.10 ms, and 0.057 ms is 0.34 % of the frame budget; an incremental update would pay the same scattered write on every cell crossing. Revision trigger 1 and the acceptance criterion of spec feature 3 are restated on that bound, which is what the runnable check now asserts. Also records the second deviation the build produced: a cell holds (Entity, Vec2) rather than Entity, because soft separation writes Transform while reading its neighbours' positions.