Make history the gate, not identity. Every challenge answer must carry the txid of its author's previous answer, chaining epochs into a relic of continuous work. Reward weight grows with chain length: a newborn face earns a crumb, a veteran full weight. A sybil farmer can mint a thousand masks, but each new chain starts as a stub, a walnut with a hollow shell. Cloning multiplies stubs, not seniority. The giveaway is the echo: a thousand newborn faces in one epoch share nothing but their youth, and youth itself becomes the flag. Attack cost scales linearly, one history per mask.