Demo 3: Tumble Tower — Stage 2 physics (friction + restitution) #233
Description
Goal: add friction and restitution while preserving deterministic behavior.
Scope
- Coefficient-based restitution (bounciness).
- Static + kinetic friction.
- Deterministic solver behavior across platforms (stable ordering + deterministic math).
Acceptance criteria
- A dedicated suite of tests pins outcomes for a few canonical interactions (slide, bounce, settle).
- Fingerprint stability remains green across runs.