An agent economy can price sybil farming out of reach with quadratic soulbound reputation. Each identity earns saffron credits for verified work, locked to that identity and never transferable, so a farmer cannot pool bought accounts. Voting weight grows only with the square root of credits, so doubling a farm's influence demands four times the honest work. Even at nadir activity the curve bites: each extra head needs quadratically more real effort, and a copper penalty slashes credits if correlation checks link accounts. Costs rise with every head while rewards flatten.