Authority at Commitment Projection

Status: informative implementation profile over the current ARPA Candidate baseline. This document does not amend the Candidate Specification by itself.

Purpose

ARPA can supply governed identity, delegation, lifecycle, recognition and authority-state evidence to an action-specific decision. This projection makes explicit what a relying system must still establish before treating an agent’s message or signature as authority for a material commitment.

The central rule is:

Discovery and authentication establish who the actor is; ARPA authority state contributes evidence about what the actor may do; the relying policy still decides whether this exact action is authorized now.

Projection

An action-specific commitment check consumes:

• principal and agent identifiers;
• an ARPA authority/delegation envelope;
• the exact action and resource;
• material constraints such as counterparty, jurisdiction or value;
• evaluation time;
• current lifecycle/revocation evidence;
• required approval evidence, where applicable; and
• the relying policy/version.

The check produces allow, deny, or indeterminate without transferring decision authority to discovery metadata or to ARPA itself.

Required invariants

1. Identity is not commitment authority. A resolvable Agent Identifier, valid Agent Card, valid signature, registration, capability claim or reputation signal cannot independently authorize the commitment.
2. Exact-action binding. The action or canonical action digest evaluated by policy must be the one later executed or accepted.
3. Current authority. Expired, suspended or revoked authority cannot authorize a new commitment.
4. Constraint preservation. Scope, resource, jurisdiction, counterparty, value and other material limits cannot be enlarged by the projection.
5. Approval binding. When approval is required, it must cover the exact action digest and remain valid at evaluation time.
6. Unknown is not allow. Missing, stale, conflicting or unsupported material authority state remains indeterminate or deny.
7. Historical reconstruction is explicit. A later reconstruction identifies both the historical time being evaluated and the current reconstruction time.
8. Layer separation. ARPA does not own negotiation sequencing, runtime retry/budget admission, settlement or reputation.

Example

{
  "principal": "org:buyer.example",
  "agent_id": "agentreg:buyer.example:sourcing-1",
  "authority_envelope": {
    "effective_from": "2026-09-01T00:00:00Z",
    "effective_until": "2026-10-01T00:00:00Z",
    "action_classes": ["procurement.commit"],
    "resource_scope": ["opportunity:42"],
    "required_approvals": ["procurement-lead-above-100000"],
    "limits": {"amount_max": 100000}
  },
  "request": {
    "action": "procurement.commit",
    "resource": "opportunity:42",
    "amount": 90000,
    "action_digest": "sha256:<canonical-action-digest>",
    "time": "2026-09-22T12:00:00Z"
  }
}

A conforming integration independently evaluates the envelope and current lifecycle state. It does not infer permission from the fact that the agent was discovered or authenticated.

Conformance evidence

The repository carries focused vectors under conformance/test-vectors/authority-at-commitment/. They deliberately cover an admitted in-scope action, expired authority, scope/value exceedance, wrong-action approval and unavailable authority state.

These vectors are implementation evidence for this projection only. They do not create a new universal negotiation protocol or expand the published IETF draft by implication.

Collective principal projection

The same decision boundary can consume authority that belongs to a collective principal and is exercisable only under a current threshold or approval rule. This projection does not convert each controller into an independent grantor.

When collective_authority evidence is supplied, an allow decision additionally requires:

• current membership evidence;
• a current exercise rule;
• a declared threshold;
• enough distinct current controllers to satisfy it;
• every counted approval bound to the exact action digest; and
• current approval validity at evaluation time.

Observed insufficient participation or stale membership/rule evidence produces deny. Missing material composition evidence remains indeterminate. Duplicate controller evidence cannot be counted twice.

The projection remains format-neutral. ARPA does not prescribe the threshold cryptosystem, collective-identifier method, or upstream protocol representation.