Function ssm_h_stored_bytes 

pub fn ssm_h_stored_bytes(h_f32_bytes: usize, f16_pool: bool) -> usize

2026-09-25: Bytes of one stored h-state blob: half of h_f32_bytes when f16_pool (FP16 elements), else h_f32_bytes. SsmStatePool::new, the preflight reserve (PoolPlan) and the SSM layer’s slot stride (ssm_h_fp16.rs) all take the stored width from here.

f16_pool is ssm_h_f16_pool_enabled() (--ssm-h-dtype f16-pool) at the production call sites; it is a parameter so pool geometry is testable without the process-global flag.

Panics when h_f32_bytes is not a multiple of 4.