Your agent wants to pay for something. Quick question: is that payment inside the authority you actually gave it?
Right now, for most agent stacks, the honest answer is “we hope so.” Agents initiate payments across x402, card rails, and delegated mandates, and the safety story is a patchwork of provider-specific checks, if it exists at all. NEXUS v0.4 is the first protocol-neutral payment-safety layer: whatever rail the payment runs on, the authority decision is deterministic, explicit, and fail-closed.
What’s new
Eight narrowly-scoped reference adapters bind external payment and delegation evidence to NEXUS authority decisions:
- SafePay Exact: x402 v2 exact payments on EVM/USDC. The amount is the amount. No variance, no surprises.
- SafePay Verified: authenticated x402 facilitator and chain evidence. The payment proof itself is verified, not just claimed.
- SafePay Variable: handles max-vs.-actual charges with reservation release, so holds don’t become charges.
- SafePay Escrow: deposit, release, refund, and mediated finality. Disputes have a mechanism, not just vibes.
- Mandate Bridge: AP2 v0.2 mandates and receipts. Delegated authority with receipts to prove it.
- Card Trust Bridge: recognizes Visa TAP requests. Explicitly not payment authorization. Recognition and authorization are different things, and this release refuses to blur them.
- Agent Token Bridge: Mastercard AP4M verifier evidence.
- Portable Delegation Bridge: KYA-OS identity and delegated authority.
Every decision runs through explicit allowlists, assurance ceilings, mandate limits, revocation checks, and cumulative exposure tracking. Malformed, stale, replayed, mismatched, or untrusted evidence is rejected. Fail-closed, every time.
“Does this agent’s proposed payment stay inside the user’s actual authority?” NEXUS v0.4 answers that question deterministically, across x402, AP2, Visa TAP, AP4M, and KYA-OS, instead of hoping each provider’s checks are enough.
One honest caveat
These are reference profiles, not production assurance. Live counterparty conformance is still pending. v0.4 defines what “safe” means and proves the decision logic; production-grade assurance against live counterparties is the next hill.
Why this matters
- Agentic commerce is already here. Agents are paying for things. The safety layer can’t arrive after the fraud does.
- Protocol-neutral beats provider-specific. One authority model across x402, AP2, card rails, and delegation frameworks. No per-provider safety snowflakes.
- Fail-closed is the only acceptable default for money. Anything that can’t be verified doesn’t go through.
- Recognition is not authorization. The Card Trust Bridge’s explicit boundary is the kind of honesty the industry needs more of.
Takeaways
- NEXUS v0.4: 8 reference adapters, 5 payment/delegation protocols, one deterministic authority model.
- Explicit allowlists, assurance ceilings, revocation, cumulative exposure. Fail-closed.
- Reference profiles; live counterparty conformance pending.
Bottom line: If your agents touch money, “we hope the provider checked” is not a safety story. NEXUS v0.4 is the beginning of a real one.
Release notes: NEXUS v0.4 on GitHub, tag 2026-09-23_NEXUS_v0.4-Safer_Payment_Authority_for_Agents.
