Mission Consumption Metering

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Table of Contents

1. Introduction

Mission-Bound Authorization for OAuth 2.0 [I-D.draft-mcguinness-oauth-mission] (the "issuance profile") bounds what an agent may do; the runtime enforcement profile ([I-D.draft-mcguinness-mission-runtime]) enforces each consequential action at the point of use. A long-running agentic task also needs bounds on how much: cumulative spend, call volume, and wall-clock activity. Those are not per-action constraints; they are counters that deplete across the life of the Mission, and enforcing them is a metering problem with reserve, commit, retry, and distributed-consistency concerns of its own.¶

This document defines that metering layer: the consumption-bounds vocabulary a Mission Intent carries, the metering semantics a runtime deployment enforces, and the AuthZEN wire binding ([I-D.draft-mcguinness-mission-authzen]) for settlement and duration-lease renewal.¶

2. Status: An EXPERIMENTAL Extension

This document is OPTIONAL and experimental: adopt it for evaluation, not as a stable interface. Metering cumulative bounds exactly under distributed decision points is a distributed-counting problem, and the reserve, commit, lease, and settlement machinery here is expected to evolve with implementation experience.¶

A deployment that does not implement this document carries no consumption bounds on its Missions and is fully conformant to the issuance and runtime profiles. The issuance profile's max_derivations is not a consumption bound: it is enforced by the issuing Authorization Server at each derivation and needs none of this document ([I-D.draft-mcguinness-oauth-mission]).¶

The consent-integrity rule of Section 6.1 is the boundary that makes this safe to omit: a bound is rendered to an Approver only where it is actually metered.¶

3. Relationship to the Issuance and Runtime Profiles

This document depends normatively on the issuance profile and the runtime profile and is not implementable alone. It defines its consumption bounds as members of the Mission Intent controls object, using the extension seam the issuance profile provides; they are carried on the Mission and committed by intent_hash exactly as any other Intent member. Metering is performed by the runtime profile's PDP within a documented enforcement scope; this document adds metering semantics to the runtime profile's decision contract and changes no issuance behavior.¶

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.¶

Consumption bound:

A cumulative bound on Mission activity that depletes as the Mission is used, as distinct from a per-action constraint that is evaluated independently on each action.¶

5. Mission Substrate

This profile is defined against the Mission model rather than against OAuth 2.0 mechanics. It consumes these substrate primitives ([I-D.draft-mcguinness-mission-substrate]): the Mission Identifier and issuer, which key every consumption counter; the Authority Set representation, from which a call_class SHOULD be drawn (Section 6); and the integrity-anchor envelope, through which the bounds are committed by intent_hash as Mission Intent controls members. It defines no binding of its own: enforcement composes through the runtime profile's Mission binding establishment step ([I-D.draft-mcguinness-mission-runtime]), and metering adds counters to the runtime decision.¶

6. Consumption Bounds

A Mission Intent controls object ([I-D.draft-mcguinness-oauth-mission]) MAY carry these members:¶

max_budget:

OPTIONAL. An object. A hard cap on cumulative monetary spend under the Mission. It carries the same {amount, currency} shape as the max_amount Common Constraint the issuance profile seeds, so the per-action cap and this cumulative cap read alike. Has the members:¶

amount:

REQUIRED. A string. A decimal number.¶

currency:

REQUIRED. A string. An ISO 4217 currency code.¶

max_calls:

OPTIONAL. An array of objects. Hard caps on the count of consequential call events. Each object has the members:¶

call_class:

REQUIRED. A string. The named call class to meter. A call_class value SHOULD be drawn from the actions identifiers of the entry's mission_resource_access ([I-D.draft-mcguinness-oauth-mission]), so the metered class maps to evaluated actions; a deployment that meters a coarser or cross-entry class defines that class's membership, and such a class is deployment-defined and not interoperable, like a deployment-defined constraint. (Named call_class rather than scope to avoid collision with the OAuth scope parameter and claim.)¶

count:

REQUIRED. An integer. 1 or greater.¶

max_duration:

OPTIONAL. A string. An ISO 8601 duration (for example, PT8H), matching the duration rule in Appendix A of [RFC3339], bounding cumulative wall-clock consequential activity under the Mission. It is distinct from the Mission's expires_at, which bounds issuance rather than activity.¶

max_egress_volume:

OPTIONAL. An object with one or both members bytes and messages, each an integer, 1 or greater: hard caps on cumulative egress under the Mission across consequential external-communication and external-commitment actions ([I-D.draft-mcguinness-mission-runtime]), as the total size in bytes of those actions' bound payload parameters and the count of such actions. It bounds the volume of within-scope laundering; it does not detect it.¶

exclusive:

OPTIONAL. An array of exclusivity groups, each an array of two or more selectors. A selector is an object with resource (REQUIRED, a string) and actions (OPTIONAL, an array of strings); it matches a consequential action whose resource equals resource and, when actions is present, whose invoked action is within it. Within a group, the selectors name authority the Approver consents MUST NOT be combined under this Mission (Section 8).¶

The bounds are carried on the Mission and committed by intent_hash. They are not enforced by the Authorization Server at issuance; they are enforced by the runtime layer at the point of use (Section 7).¶

Example Mission Intent controls carrying three of the four bounds alongside the issuance profile's members:¶

{
  "controls": {
    "acr": "urn:example:acr:mfa",
    "max_derivations": 200,
    "max_budget": { "amount": "5000.00", "currency": "USD" },
    "max_calls": [
      { "call_class": "journal-entries.write", "count": 50 }
    ],
    "max_duration": "PT8H"
  }
}

7. Consumption Metering

Consumption bounds are enforced by the runtime profile's PDP ([I-D.draft-mcguinness-mission-runtime]), not at issuance:¶

• max_budget: the PDP performs an atomic reserve-or-charge against the remaining balance for each consequential action and MUST refuse when the remaining balance is insufficient.¶

• max_calls: the PDP increments an atomic counter for the named call_class and MUST refuse a call past count.¶

• max_egress_volume: the PDP adds the action's bound payload size and increments the action count atomically with the permit and MUST refuse an action that would exceed either cap. Payload size is measured over the parameter bytes committed by parameter_digest ([I-D.draft-mcguinness-mission-runtime]); the operation profile defines the measurement so PDPs accumulate consistently.¶

• max_duration: the PDP accumulates the duration of consequential activity it reserves, commits, or permits and MUST refuse once that total would exceed the bound. For an action whose duration is not known before execution, the PDP MUST either reserve a bounded maximum duration or issue a duration lease that expires unless renewed; the PEP MUST stop the action or obtain a new permit before the reservation or lease is exhausted. After execution, the PEP MUST report the measured duration so the PDP can commit actual use and release any unused reservation. The operation profile defines how a single action's duration is measured so that PDPs accumulate consistently.¶

A per-entry constraints value that expresses a cumulative consumption bound is metered the same way. When an applicable entry or the Mission's controls carries such a bound, the PDP MUST meter use against it and MUST refuse a consequential action that would exceed it. The runtime profile's fail-closed rule stands beneath all of this: an unmetered or unrecognized consumption bound MUST cause refusal rather than silent pass-through ([I-D.draft-mcguinness-mission-runtime]).¶

8. Exclusivity and Separation of Duty

The exclusive control (Section 6) is not a consumption bound: it is a stateful separation-of-duty rule enforced with the same machinery. Within an exclusivity group, the first permitted consequential action matching a selector latches the group to that selector, atomically with the permit; for the Mission's remaining lifetime the PDP MUST refuse a consequential action matching any other selector of the same group. The latch is per group and per Mission, is PDP-side operational state like a consumption counter (Section 7), and never unlatches: narrowing by exercise is monotonic, like every other narrowing in the family.¶

Exclusivity turns the quarantine deployment pattern ([I-D.draft-mcguinness-mission-architecture]) into consented, enforceable structure: an Approver can approve a Mission that may read a sensitive store or communicate externally, but never both. The groups are consented at the approval event, committed by intent_hash with the other controls members, and rendered in the consent disclosure (Section 6.1 applies unchanged).¶

In the AuthZEN binding, a refusal under a latched group is denied with exclusivity_latched, an extension of the runtime denial set under the AuthZEN profile's coordinated-extension conventions ([I-D.draft-mcguinness-mission-authzen]), and recorded as the denial_reason in Decision Evidence. A PDP that cannot establish a group's latch state fails closed for the actions the group covers, per the runtime profile's availability posture.¶

9. Aggregate Bounds

The bounds of this document are Mission-keyed. A deployment MAY additionally meter the same bound classes across Missions, keyed by the Mission's subject or by the approved client_id, so a fleet operator can cap what an agent identity or a Subject consumes in total rather than per task. The counter semantics, reserve/commit postures, and refusal behavior are unchanged; only the key differs.¶

An aggregate bound is deployment policy: it is carried on no single Mission Intent, is committed by no intent_hash, and is disclosed through the deployment's enforcement-scope statement rather than the approval event. A refusal under an aggregate bound is carried as quota_exceeded, and Decision Evidence records the deployment-defined aggregate key class.¶

Aggregate keying crosses the family's per-Mission consistency domains: a subject-keyed counter is shared by every Mission the subject holds, so it cannot be sharded by Mission Identifier and is provisioned as its own consistency domain ([I-D.draft-mcguinness-mission-runtime]).¶

10. AuthZEN Binding

Where the runtime deployment uses the AuthZEN binding ([I-D.draft-mcguinness-mission-authzen]), this section defines the wire representation of metering. It defines no new metering semantics and no new constraint.¶

When metering a bound would exceed it, the PDP MUST deny with quota_exceeded ([I-D.draft-mcguinness-mission-authzen]) instead of returning a permit, and MUST record quota_exceeded as the denial_reason in Decision Evidence. Whether a metered permit is reserved at decision time and committed on settlement, or committed at decision time, follows the deployment's documented reserve/commit posture (Section 7.2); this binding fixes neither. In a batch (boxcar) evaluation, consumption metering applies per item in request order. The exactness of the bound is the consistency bound of Section 7.1, not a property of this wire binding.¶

{
  "subject": {
    "type": "user",
    "id": "user_3p2q8mN1a0kV7tR",
    "properties": {
      "iss": "https://idp.example.com"
    }
  },
  "resource": {
    "type": "ledger",
    "id": "ledger_main"
  },
  "action": { "name": "reconciliation.run" },
  "context": {
    "mission": {
      "id": "msn_8RfX2Lqv9TqMv4z7sA2bN1k0YpEdHc9-",
      "issuer": "https://as.example.com",
      "authority_hash":
        "sha-256:l3KvZ4mP5x0wQrR6tY2nD9bM7sX1cF8gH2vJ4kE5pNQ",
      "state": "active"
    },
    "actor": { "client_id": "s6BhdRkqt3" },
    "credential": {
      "issuer": "https://as.example.com",
      "expires_at": "2026-11-02T09:14:00Z"
    },
    "audience": "https://erp.example.com",
    "freshness": {
      "mode": "fresh",
      "freshness_at": "2026-11-02T08:44:00Z"
    },
    "prior_decision_id": "dec_0Rt5nB8xW2qK7mJ4vS1pL9eYc"
  }
}

11. Conformance

A runtime deployment that claims this profile MUST:¶

• meter every consumption bound a governed Mission carries per Section 7, within its documented runtime enforcement scope ([I-D.draft-mcguinness-mission-runtime]);¶

• refuse a consequential action that would exceed a bound, and refuse on any bound it cannot meter;¶

• enforce every consented exclusivity group with a latch atomic with the permit (Section 8);¶

• where aggregate bounds are configured, meter and disclose them per Section 9;¶

• publish its consistency bound under a multi-PDP topology (Section 7.1);¶

• define and document its retry, idempotency, and reserve/commit posture (Section 7.2); and¶

• where the AuthZEN binding is in use, implement the settlement exchange of Section 10.1.¶

A Mission Issuer in a deployment claiming this profile MUST carry the consented bounds on the Mission record committed by intent_hash, and MUST render them at the approval event per Section 6.1.¶

12. Security Considerations

Consumption bounds limit the blast radius of a compromised or runaway agent in a dimension authority narrowing cannot: a Mission whose every action is individually authorized can still be drained by volume. Their enforcement, however, is only as good as the metering:¶

• Unenforced bounds are consent theater. A bound rendered at approval but not metered anywhere misleads the Approver about the Mission's exposure. The consent-integrity rule (Section 6.1) exists for this; a deployment that cannot meter MUST NOT render the bound as enforced.¶

• Distributed undercounting. Under a multi-PDP topology, an attacker who can spread actions across decision points exploits the consistency gap. The published consistency bound (Section 7.1) is the honest statement of that exposure; per-PDP sub-budgets bound it structurally.¶

• Settlement honesty. The PDP commits what the PEP reports. Execution Evidence is integrity-protected and signed by the PEP ([I-D.draft-mcguinness-mission-authzen]); a compromised PEP can under-report duration or spend, which is within the runtime profile's trusted-base assumptions for PEPs.¶

• Lease abandonment. An agent that stops renewing a duration lease and keeps acting is stopped by the PEP, which MUST stop the action or obtain a new permit before the lease is exhausted (Section 7).¶

13. Privacy Considerations

Metering state (spend, call counts, activity durations) is a fine-grained record of Mission activity over time. It SHOULD be retained under the same access controls and retention windows as runtime enforcement evidence ([I-D.draft-mcguinness-mission-runtime]), and disclosed in decision responses only as refusals, not as remaining-balance oracles.¶

14. IANA Considerations

This document has no IANA actions. max_budget, max_calls, max_duration, max_egress_volume, and exclusive are Mission Intent controls members defined by this profile under the issuance profile's controls extension seam; context.prior_decision_id and measured_duration are AuthZEN extension data carried per the AuthZEN profile's conventions ([I-D.draft-mcguinness-mission-authzen]).¶

15. References

Acknowledgments

This document is part of the Mission-Bound Authorization for OAuth 2.0 work and defines its experimental consumption-metering layer.¶

Author's Address