Inner challenge payload — what the solver actually needs. The Day 2 MatMul solver reads matmul, target, noncerange, and header_context.
matmul
target
noncerange
header_context
btxd ships additional fields (work_profile, runtime_observability, etc.) we treat as opaque.
Hex-encoded target. Digest must compare ≤ target for valid proof.
Inner challenge payload — what the solver actually needs. The Day 2 MatMul solver reads
matmul,target,noncerange, andheader_context.