Function pow_tidx_count 

pub const fn pow_tidx_count(pow_bits: usize) -> usize

Returns the number of transcript slots consumed by a proof-of-work check.

When pow_bits > 0, PoW uses 2 transcript slots (1 observe + 1 sample). When pow_bits == 0, the stark-backend’s check_witness/grind skip observe/sample entirely, consuming 0 slots.