Constant FRAME_BYTES 

pub const FRAME_BYTES: f64 = _; // 1664f64

Bytes written per signature (one 2 KiB frame slot, 26 beats used).

Unit: bytes. A beat is one 64-byte HBM write. The 1,642-byte signature plus its message index needs 26 beats; the rest of the 2 KiB slot is not written, so only 26 × 64 bytes count against port bandwidth.