Function ``byte_pattern_echo_eq``: array<ui8, 8> -> ui8.
Compares the incoming 8-byte array against the same constant pattern as
:class:`BytePatternConst` and returns ``1`` if every element matches,
``0`` otherwise. The driver writes **raw wire bytes** straight into the
arg channel, taking the host-side serializer out of the loop. A test
failure means the bytes the runtime put on the wire disagree with the
spec, not that the host SW ``de``serializer also misread them.
Definition at line 98 of file serialization_probes.py.