pub const SCRATCHPAD_HEAD_LEN: usize = 128; // 128usizeExpand description
Bytes of the running Instance’s scratchpad (slot[0]) region surfaced at the
top-level HALT — a fixed-size head of the returned DataCap’s effective
content. The guest writes its result into the scratchpad-mapped memory
region during the run (CoW into the cap); at top HALT the engine reads the
region’s effective bytes back out here, so the host observes the full,
uncompressed result without a separate data-flow event.
V1 surfaces a fixed-size window (enough for the fuzz differential’s 13-slot
register signature: 13 × 8 = 104 ≤ 128). The full variable-length DataCap
return is deferred to the YieldMarker/YieldCatcher kernel design — see
kernel-assisted-instances.md. Zero-filled when the Instance maps no
scratchpad region (every non-fuzz path today).