Function ``byte_pattern_const``: ui8 -> array<ui8, 8>.
Ignores the trigger byte and returns the constant pattern
``[0x12, 0x34, 0x56, 0x78, 0x9A, 0xBC, 0xDE, 0xF0]`` (in PyCDE / MLIR
index order). The driver consumes the result as **raw wire bytes**
rather than through the typed deserializer, so any host-side decoding bug
(including a symmetric one) is taken out of the loop entirely. A test
failure here points at a mismatch between the runtime's wire convention
and the spec, not at a SW round-trip.
Definition at line 67 of file serialization_probes.py.