Mission Deferred Approval for OAuth 2.0

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Table of Contents

1. Introduction

The issuance profile [I-D.draft-mcguinness-oauth-mission] (the "issuance profile") derives an Authority Set from a submitted Mission Intent and records an approval event at which an Approver consents to that authority. It specifies what the approval commits, not how the approval is obtained over time. Two facts about agent approval are left unspecified:¶

• A human Approver review is asynchronous: the agent submits a proposed Mission and must wait, sometimes for a long time, for a decision.¶

• A reviewer commonly approves a narrowed subset of the proposed Mission, not an all-or-nothing outcome. With no way to revise in place, the agent must abandon the proposal and submit a new one, losing the approval state and any preceding work.¶

This document supplies both. It profiles OAuth Deferred Token Response [I-D.draft-gerber-oauth-deferred-token-response] (the "deferred substrate") so a Mission approval can be deferred and polled, and it defines a revisable approval mode: when the Authorization Server can grant only a narrowed version of the proposed Mission, it signals which dimensions it refused and invites the client to push a narrowing revision, then continues the same deferred approval. The client keeps its place; the approval resolves over the narrowed proposal.¶

This is narrowing only. A revision can reduce the proposed Mission; it can never broaden it. Widening an approved Mission is a different operation with its own fresh approval ([I-D.draft-mcguinness-oauth-mission-expansion]).¶

2. Status: An OPTIONAL Extension

This document is OPTIONAL. A deployment that obtains Mission approvals synchronously, or that abandons and resubmits when a reviewer narrows a proposal, is fully conformant to the issuance profile and is unaffected by this document. It places no new requirement on the issuance profile.¶

A deployment claims this profile only when it defers Mission approvals under the deferred substrate or accepts revisable approvals. The approval event, the Authority Set, the subset rule, and the integrity anchors are unchanged; this document governs only how the approval is reached over time.¶

3. Relationship to the Issuance Profile

This document depends normatively on the issuance profile and on the deferred substrate, and is not implementable alone. It reuses, without restating, the issuance profile's Mission Intent, submission via PAR [RFC9126], authority derivation, approval event, subset rule, and integrity anchors, and the deferred substrate's deferral response, continuation polling, cancellation, and sender-constraint rules. It uses the terms Agent (Client), Approver, Mission Issuer, Mission Intent, and Authority Set as the issuance profile defines them, and completion_mode, deferral_code, and the deferred grant type as the deferred substrate defines them.¶

4. Conventions and Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶

Proposed Mission:

The Mission Intent and the Authority Set the Mission Issuer derived from it, pending an approval decision.¶

Revision:

A narrowing of the proposed Mission, submitted by the client while the approval is deferred, that replaces the proposed Mission's Authority Set with a subset of it.¶

5. Deferred Mission Approval

A Mission approval MAY be deferred. The client submits the Mission Intent through PAR as the issuance profile requires, and includes deferred among the completion_mode values on the resulting token request, opting in to the deferred substrate ([I-D.draft-gerber-oauth-deferred-token-response]). When the Mission Issuer cannot decide the approval immediately, for example because it routes the proposed Mission to a human reviewer, it returns the substrate's deferred response (authorization_pending with a deferral_code) instead of a token, and the client polls with the deferred grant type until the approval resolves to a Mission-bound token response, access_denied, or expired_token.¶

Deferral changes only the timing of the approval event. The Authority Set the token is issued against, its authority_hash, and the recorded consent are exactly as in a synchronous approval.¶

6. Revisable Approval

A client signals that it accepts a narrowing revision by including revisable among its completion_mode values alongside deferred:¶

completion_mode=deferred revisable

revisable is a completion-mode value registered in the deferred substrate's OAuth Completion Mode Values registry (Section 12). It authorizes only the revision handshake defined here. A Mission Issuer MUST NOT invite a revision unless the client offered revisable. revisable has effect only together with deferred; a Mission Issuer that receives revisable without deferred MUST ignore it, because there is no deferred approval to revise.¶

HTTP/1.1 400 Bad Request
Content-Type: application/json
Cache-Control: no-store

{
  "error": "authorization_pending",
  "deferral_code": "dc_9P2K7zT1mX8b3N",
  "revision_required": true,
  "clarification_handle": "ch_4QFJ3P9",
  "rejected_scope": "crm:write",
  "rejected_authorization_details": [
    { "type": "payment", "limit": "10000" }
  ],
  "expires_in": 420,
  "interval": 5
}

7. Integration with the Mission Suite

Consent evidence:

A revised proposed Mission is a different disclosure. Where a deployment records Consent Evidence ([I-D.draft-mcguinness-oauth-mission-consent-evidence]), the re-reviewed revision MUST get a fresh consent_rendering_hash; prior consent does not transfer to the narrowed proposal.¶

Shaping:

The rejected_scope and rejected_authorization_details parameters are the machine-readable input a client-side shaper ([I-D.draft-mcguinness-oauth-mission-shaping]) uses to plan the narrowed revision. Shaping narrows a proposal before submission; this profile narrows it during review. Together they let an orchestrator propose, learn what was refused, and re-propose without losing state.¶

Integrity anchors:

The approval commits the final, narrowed Authority Set. The intent_hash and authority_hash are computed over the revised Mission Intent and Authority Set actually approved, not the originating proposal.¶

This profile narrows only, and only while an approval is deferred. It is distinct from widening an approved Mission, which requires a fresh approval ([I-D.draft-mcguinness-oauth-mission-expansion]), and from drawing authority from a pre-consented ceiling without a per-step human (progressive authorization, [I-D.draft-mcguinness-oauth-mission-expansion]).¶

8. Worked Example

Agent s6BhdRkqt3, acting for alice, proposes a Mission to reconcile Q3 invoices that asks for both read and write on the ERP. It submits the Mission Intent through PAR and opts in to both deferral and revision on the token request:¶

POST /token HTTP/1.1
Host: as.example.com
Content-Type: application/x-www-form-urlencoded

grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA&
client_id=s6BhdRkqt3&
completion_mode=deferred%20revisable

The Mission Issuer routes the proposed Mission to alice for review and defers:¶

HTTP/1.1 400 Bad Request
Content-Type: application/json
Cache-Control: no-store

{ "error": "authorization_pending",
  "deferral_code": "dfc_7M2R4kP9sT1x",
  "expires_in": 600, "interval": 5 }

The agent polls with the deferred grant type. On review alice approves read but not write. Rather than deny, the Mission Issuer narrows and invites a revision, extending the pending response:¶

HTTP/1.1 400 Bad Request
Content-Type: application/json
Cache-Control: no-store

{ "error": "authorization_pending",
  "deferral_code": "dfc_7M2R4kP9sT1x",
  "revision_required": true,
  "clarification_handle": "clh_4QFJ3P9wZ2",
  "rejected_authorization_details": [
    { "type": "mission_resource_access",
      "resource": "https://erp.example.com",
      "actions": ["journal-entries.write"] } ],
  "expires_in": 540, "interval": 5 }

The agent pushes a narrowed Mission Intent, dropping the write, to PAR with the clarification handle:¶

POST /par HTTP/1.1
Host: as.example.com
Content-Type: application/x-www-form-urlencoded

mission_intent=%7B...read-only%20Q3%20invoices...%7D&
client_id=s6BhdRkqt3&
clarification_handle=clh_4QFJ3P9wZ2

The Mission Issuer verifies the handle, confirms the revised Authority Set is a subset of the proposed one, updates the deferred approval, and re-reviews (here, policy auto-approves the now-narrower read-only Mission). The agent keeps polling the same deferral_code, which now resolves to a Mission-bound token over the final, narrowed authority:¶

HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store

{ "access_token": "eyJ...",
  "token_type": "DPoP",
  "expires_in": 300,
  "authorization_details": [
    { "type": "mission_resource_access",
      "resource": "https://erp.example.com",
      "actions": ["invoices.read"],
      "constraints": { "period": "2026-Q3" } } ],
  "mission": {
    "id": "msn_8RfX2Lqv9TqMv4z7sA2bN1k0YpEdHc9-",
    "origin": "https://as.example.com",
    "authority_hash":
      "sha-256:l3KvZ4mP5x0wQrR6tY2nD9bM7sX1cF8gH2vJ4kE5pNQ" } }

The agent never abandoned its request; the approval resolved over the narrowed proposal, and the committed authority_hash is over the read-only Authority Set actually approved.¶

9. Conformance

A Mission Issuer conforming to this profile MUST:¶

• support the deferred substrate for Mission approvals it defers;¶

• offer a revision only when the client signaled revisable;¶

• enforce that a revision is a subset of the proposed Mission under the issuance profile's subset rule, never a broadening;¶

• treat each clarification_handle as single-use and sender-constrained to the deferred approval; and¶

• commit the approval over the final narrowed Authority Set.¶

A client conforming to this profile MUST treat a revision-required response as unapproved, submit only narrowing revisions, and continue polling the existing deferral_code.¶

10. Security Considerations

The deferred substrate's security considerations apply in full, including deferral-code entropy, sender-constraint continuity, cancellation, and oracle resistance. This section adds only what the revision handshake introduces.¶

• Narrowing only. A revision MUST NOT broaden the proposed Mission on any dimension. The Mission Issuer enforces the subset relation per parameter (scope, resource, audience, authorization_details) before re-review.¶

• Single-use handle. A clarification_handle MUST be invalidated after one submission, success or failure. A new handle is issued on a subsequent revision-required response.¶

• Sender-constraint continuity. The handle MUST be sender-constrained to the same key as the deferral_code. An attacker holding the handle without the key cannot push a revision.¶

• Handle lifetime. The handle lifetime MUST NOT exceed the remaining lifetime of the deferral_code, and SHOULD be shorter when the handle is exposed to orchestration layers outside the OAuth client.¶

• Stale consent. A re-reviewed revision MUST be presented to the reviewer as a new disclosure with a fresh consent commitment (Section 7); prior consent does not transfer.¶

• Policy disclosure. rejected_scope and rejected_authorization_details can reveal policy boundaries; a Mission Issuer SHOULD disclose only the minimum needed to narrow and MAY omit them.¶

• Revision bounding. A Mission Issuer MUST bound revision cycles per deferred approval and resolve to access_denied at the bound (Section 6.2), and SHOULD log excessive cycles as a security event, so a client cannot drive an unbounded reshape-and-retry loop to wear down a reviewer.¶

11. Privacy Considerations

The rejected-dimension parameters and the revision history reveal what authority an agent sought and was refused. A Mission Issuer SHOULD treat them as sensitive, minimize what it discloses, and retain revision history under the same controls as other approval-event records.¶

12. IANA Considerations

This document registers one value in the OAuth Completion Mode Values registry established by the deferred substrate ([I-D.draft-gerber-oauth-deferred-token-response]):¶

• revisable: Change Controller IETF; Reference this document, Section 6.¶

This document registers the following in the "OAuth Parameters" registry. For each: Change Controller IETF; Reference this document, Section 6.1.¶

• revision_required (token endpoint response)¶

• clarification_handle (token endpoint response, PAR request)¶

• rejected_scope (token endpoint response)¶

• rejected_authorization_details (token endpoint response)¶

PAR [RFC9126] carries the revision as authorization-request parameters without a distinct usage location, so the pushed submission of the narrowed Intent and clarification_handle needs no separate registration.¶

13. References

Acknowledgments

This document is part of the Mission-Bound Authorization for OAuth 2.0 work and profiles OAuth Deferred Token Response for asynchronous, revisable Mission approval.¶

Author's Address