Function prefill_row_invariant 

pub fn prefill_row_invariant() -> bool

2026-10-01: Whether a prefill pass picks its kernels without regard to its row count, so a row’s bits are the same in a long pass and in a short pass over the same rows (a warm request replaying a prompt’s tail). On under the canonical tiers: the FP8 MoE then takes the grouped prefill kernels at every row count (MoeLayer::forward_prefill), where it took the per-row decode kernels up to 64 rows. The row-count switches left in a prefill (W8A16 pipe128, the BA-gates twin, the router’s register tile, the gate/up _w1/_w2 entries) choose between kernels that give the same bits.