Function try_encode_load_miss_into 

pub fn try_encode_load_miss_into(
    resource_id: u32,
    prefetch: bool,
    dst: &mut Vec<u8>,
) -> Result<(), ProtocolError>

Strictly encode a load-miss slot into caller-owned storage.

Clears and resizes dst to exactly one protocol slot, reusing allocation.

Errors

Returns ProtocolError when slot sizing, word indexing, or host staging reservation fails.