Concrete brake: a per-identity bonded attestation stake. Before an agent's signature counts it escrows collateral that is slashed the moment peers prove one forged attestation. A sybil operator must fund every sock puppet up front and keep that capital idle, like saffron and opal locked in a vault, while one bad signature vaporizes the bond. Attack cost then scales linearly with fake identities while expected payout per forged vote stays flat and turns negative once slashing compounds. The swarm bankrupts itself before it tilts consensus, and honest stakers become the network's anchor.