D21 — RUDY overflow and pin density as routability term

Decision

Routability term is RUDY overflow + pin density on a ≤ 32×32 grid, integer nm, power nets excluded; the router loop shrinks bin capacity around failed connections

Alternatives

Electrostatic R(x) in global placement; airwire-crossing density only

Reason

Cheap to keep incremental and exact in the annealer (reference = from-scratch recompute); capacity shrinking is the PCB analogue of RePlAce cell inflation