The ERC-8354 characterization is accurate – CAPV keeps the ruleset confidential, this keeps the execution credential from being replayed, and neither one needs the other to function. Good example of neighbouring standards actually staying in their lane instead of overlapping.
One thing worth naming explicitly in the “Relationship to Neighbouring Standards” section: this guarantees exactly-once execution of a specific authorized payload, but says nothing about whether that payload should have been authorized in the first place. A compromised agent replaying a stolen credential and a legitimate agent executing a genuinely bad decision produce the same on-chain shape from this standard’s point of view – both are “a valid, unreplayed nullifier consumed once.” That’s not a gap in this proposal (scope says as much – “not an access control framework”), just worth being explicit that unclonability and soundness are orthogonal properties a system needs both of, not substitutes for each other.
On the cross-chain nullifier-registry-mirroring question: we’ve dealt with a structurally adjacent problem – avoiding a single point of trust for verifying a signed artifact – by publishing to multiple independent relays/nodes rather than one authoritative registry, and letting a verifier check any of them (or recompute locally from the signature). Doesn’t solve your race-condition problem directly since a nullifier registry needs actual consensus on “has this been spent,” not just availability – but if the failure mode you’re most worried about is a single mirror going down or lying, redundant independent mirrors with local recomputability might be worth a look even if full cross-chain consensus stays the harder open problem.