0x hardens swap infrastructure with verified AllowanceHolder and audits

0x is hardening its swap infrastructure around the contracts that hold users' token approvals. Its AllowanceHolder contract has been formally verified by @bailsecurity on the Certora Prover, mathematically proving the contract is correct — the same assurance used by Aave and Uniswap. Few other swap aggregators claim this level of verification.

Per the verification, approvals cannot outlive the transaction even against a hostile callee, an allowance is scoped to exactly one (operator, owner, token) and cannot be over-spent, and failed calls roll back atomically.

0x also points to Immutable Settler contracts and audits by Trail of Bits, OpenZeppelin, Dedaub, and Ouroboros, plus its SOC, as part of a broader security posture for its swap infrastructure.