Long-running agents discover mid-task that they need a destination their egress proxy does not allow, and the block comes back as an opaque connection failure with no machine-actionable way to ask for access and no human standing by. That block is a requestable denial, and the egress proxy is a policy enforcement point. RFC 8908, the Captive Portal API, supplies the recovery state machine for a blocked client on a network: discover captivity, learn the remediation endpoint, and retry after policy changes. A headless agent can use that state machine, with the denial carried by Proxy-Status and Problem Details where an HTTP response exists and by an authenticated side-channel status API where it does not. The recovery can ride the captive portal at two altitudes, destination-level on a proposed AuthZEN Access Request profile or operation-level on AAuth and Mission-bound authority. When the client already speaks AAuth, it needs no captive-portal shim at all, because AAuth carries the refusal and re-authorization in-band at the same request boundary the proxy already enforces.
Re-subjecting across a SaaS boundary is a mint, not an attenuation, so the IdP must issue each onward grant. ID-JAG covers the first hop, where an application holds the user’s ID Token or SAML assertion to exchange. Subsequent hops hold no end-user credential, which leaves a gap: the intermediate has nothing to present to the IdP to continue the chain. The Identity Continuation Assertion fills it. It is a short-lived, sender-constrained JWT, issued by a Chain Authority the IdP trusts, that carries opaque evidence of the in-flight delegation and is presented as the Token Exchange subject token to request an onward ID-JAG. It is evidence, not authority: it carries no subject and grants no access, the IdP resolves the target audience’s subject and re-decides at every hop, and the continuation handle never reaches a Resource Server.
Evals Made Intent Executable for Verification. A Mission Makes It Executable for Authorization.
Microsoft’s ASSERT compiles written behavior requirements into executable evaluations: intent made executable for verification. That answers what the agent did, not what it was allowed to do: an eval produces a verdict, not a binding authorization decision, and for irreversible actions that is the whole difference. The mission is the preventive counterpart: a shaper proposes the request as a bounded, machine-readable object, a trusted authority validates and narrows it, an approver signs off, and enforcement checks every consequential action against it. Same lineage from natural-language intent, a higher bar, and teeth an eval does not have. One approved mission then drives both the runtime boundary and the behavioral eval, while a separate shaping-quality check asks whether the boundary matched the user’s intent in the first place.
In Cross-App Access, a single signed-in user’s identity has to cross applications that each name them under a different subject. Workload identity proves which service is calling, not which user delegated the work, and offline attenuation can narrow authority it already holds but cannot create a binding to a name it was never given. So crossing a subject namespace is a mint, not an attenuation: only the IdP or broker that owns the mapping can issue new audience-scoped identity evidence, while the destination Authorization Server still applies its own policy and mints the access token. The same shape holds on the authorization axis, where a different scope or policy model forces a non-amplifying re-mint rather than a narrowing. The open question is not whether that mapping authority is in the loop but how it is invoked: caller-pushed continuation, resource-pulled resolution, or another profile that preserves the trust invariant.
Closed-world authorization treated denial as the end of the interaction. Agents, runtime discovery, delegation, and mission expansion turn denial into the beginning of governance escalation. The draft AuthZEN access request and approval profile standardizes that handoff without standardizing the workflow engines behind it. Client-Initiated Backchannel Authentication (CIBA) is not the answer because the problem is not authentication freshness. It is whether authority should continue under newly discovered runtime conditions.
WorkOS auth.md is an agent-readable registration document for one-click setup, with Agent Verified, user-claimed, and anonymous paths. In the Agent Verified path, most pieces already exist across OAuth and OpenID standards: ID-JAG, OAuth metadata, dynamic client registration, standard token endpoints, and SSF/CAEP/OPC. The standards gap is a profile for runtime agent onboarding and trust establishment, not a new grant protocol.
Client instances are not new clients. They are actors. With the Actor Profile and the act chain already in place, and an instance_issuers field that fits any client registration channel (static, Dynamic Client Registration, or CIMD), treating instances as first-class actors needs no new grant type, no new client type, and no new claim. It needs a profile that ties them together.
The new version of AAuth (draft-hardt-aauth-protocol-01, since resubmitted as draft-hardt-oauth-aauth-protocol) materially changes the earlier comparison. Mission is now first-class in the protocol, with PS-mediated approval, mission-aware token choreography, and governance endpoints. The remaining gap is no longer whether Mission exists, but whether the published model is strong enough to support portable containment rather than just mission correlation and governance hooks.
Open-world OAuth can improve discovery, resource binding, and first-contact trust. That still leaves the harder agent problem: how approved intent becomes bounded authority that stays governed across delegation chains, unfamiliar tools, consent expansion, revocation, and task termination.
OAuth was built for closed worlds, and that constraint is why it became mature. Agents expose the limits of that deployment model. This post traces what the newer OAuth standards get right and which substrate gaps still need to close.
The current split between token exchange semantics and JWT access token practice creates avoidable interoperability failures. A common profile for act, grounded in entity profiles, can align JWT assertion grant and JWT access token processing.