[BIP Draft] Co-signer Spending Policies

The signing process in statement-v0 involves the event ID, outcome, and timestamp but does not specify whether the outcome is final. This omission could allow a co-signer to act on an initial answer that might subsequently be changed or corrected. To address this, a finality flag will be incorporated into the signed tuple, enabling evidence conditions to require confirmation of finality before actions are taken.

In scenarios such as escrow, the system will demand a final statement to ensure outcomes are definitive. However, if an attestor never marks an outcome as final, the template can accommodate this by allowing for a waiting period corresponding to a dispute window. For attestations utilizing Discreet Log Contract (DLC) nonce pre-commitment, finality is inherently enforced. Signing multiple outcomes for the same event in this context would expose the attestor's key, providing built-in security against conflicting statements.

Test vectors will be provided to define the exact bytes representing policy IDs. These vectors will be distributed alongside the chosen serialization format, ensuring consistent implementation and verification across different systems.