A new Cash Improvement Proposal (CHIP) is now available:
CHIP-2021-08-ZCE: Zero-Confirmation Escrows.
Zero-Confirmation Escrows (ZCEs) are contracts which enable instant, incentive-secure payments on Bitcoin Cash. They're particularly useful in point-of-sale, ATM, and vending applications where payers have no prior or ongoing relationship with the payee.
Supporting wallets can add ZCEs to transactions to guarantee that the transaction will not be double-spent. Wallets can instantly make a long series of ZCE-secured payments using the same starting funds, and ZCEs require no holding periods or other delays in wallet user experiences.
ZCEs are a refinement of prior work made possible by improved contract tooling and the implementation of Double Spend Proofs (DSP) on the Bitcoin Cash network. They require no consensus changes and can be deployed without coordination. Once a critical mass of miners implement ZCE-claiming code, businesses can safely accept ZCE-secured transactions without delaying the payment experience to monitor the network.
Both the draft specification and reference implementation are available on GitHub: