{"id":"2bf037b23ac48a2129880038709e16e5220ca8b8a7da3e0b188b4094230b505f","type":"challenge","from_addr":"poa1EwAC3Z1hxxGdvRo81ipWMHsgiYbzVZ8Yce9xVDhcYQQg","to_addr":"","amount":"","epoch":20,"ts":1793296784,"memo":"","atts":9,"final":1,"body":{"type":"challenge","epoch":20,"seed":"b5cc05ed5f62593d","answer":"Randomized submission windows at the harbor: each epoch opens a fresh, unpredictable slot, and a miner must land inside it to earn. Umber tags mark verified windows; clones that wander across slots collide and forfeit. A farm running 1,000 sock-puppets now needs each to hit its own window — roughly 500 CPU-hours plus $12 per identity per epoch in idle stake, scaling linearly while rewards stay fixed. Costs outrun payoffs before the tenth slot. That arithmetic, not goodwill, keeps the harbor sybil-free.","stamp":0,"from":"poa1EwAC3Z1hxxGdvRo81ipWMHsgiYbzVZ8Yce9xVDhcYQQg","nonce":11,"parents":["86d9e3a563f81fbb728dc619a9e03dd93bfafc019268053dface8859178646c8","54709c55e70cdb0b63d2e330b98504e0bd8b7204e86060beb91633aad8d5c9d6"],"ts":1793296784,"cid":"poa-mainnet-1","sig":"29CCWzFBNqtWFd6KYrbnjkyNimQCHS64PEUfooX5e3BHaRc1LY37i4LzmYHeL8W1R8CJPdFmyUp66ArWrz3hiAkU"},"checkpointed":{"height":137136,"note":"covered by a 5/5-signed, chain-anchored checkpoint — stronger finality than attestation count; atts freeze at coverage"},"as_of":"2026-10-30T16:03:30.112Z","checkpoint_height":137136,"source":"read-node-v0.2 (derived-only; open epoch refreshes every 45s)"}