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<rfc ipr="trust200902" docName="draft-nennemann-act-01" category="std" consensus="true" submissionType="IETF" tocInclude="true" sortRefs="true" symRefs="true">
  <front>
    <title abbrev="ACT">Agent Context Token (ACT)</title>

    <author fullname="Christian Nennemann">
      <organization>Independent Researcher</organization>
      <address>
        <email>ietf@nennemann.de</email>
      </address>
    </author>

    <date year="2026" month="April" day="12"/>

    <area>SEC</area>
    
    <keyword>agent authorization</keyword> <keyword>execution accountability</keyword> <keyword>JWT</keyword> <keyword>DAG</keyword> <keyword>delegation</keyword>

    <abstract>


<?line 167?>

<t>This document defines the Agent Context Token (ACT), a self-contained
JWT-based format that captures the full invocation context of an
autonomous AI agent — its capabilities, constraints, delegation
provenance, oversight requirements, task metadata, and DAG position —
and unifies authorization and execution accountability in a single
token lifecycle. An ACT begins as a signed authorization mandate and
transitions into a tamper-evident execution record once the agent
completes its task, appending cryptographic hashes of inputs and
outputs and linking to predecessor tasks via a directed acyclic graph
(DAG). ACT requires no Authorization Server, no workload identity
infrastructure, and no transparency service for basic operation. Trust
is bootstrapped via pre-shared keys and is upgradeable to PKI or
Decentralized Identifiers (DIDs). ACT is designed for
cross-organizational agent federation in regulated and unregulated
environments alike. ACT is the general-purpose agent context
primitive; the WIMSE Execution Context Token (ECT)
<xref target="I-D.nennemann-wimse-ect"/> is a sibling profile specialized for
workload-identity-bound execution recording in WIMSE deployments.</t>



    </abstract>



  </front>

  <middle>


<?line 188?>

<section anchor="introduction"><name>Introduction</name>

<t>Autonomous AI agents increasingly operate across organizational
boundaries, executing multi-step workflows where individual tasks are
delegated from one agent to another. These workflows create two
distinct, inseparable compliance requirements:</t>

<t><list style="numbers" type="1">
  <t><strong>Authorization</strong>: was the agent permitted to perform the action,
under what constraints, and by whose authority?</t>
  <t><strong>Accountability</strong>: what did the agent actually do, with what
inputs, producing what outputs, in what causal relationship to
prior tasks?</t>
</list></t>

<t>Existing specifications address these requirements in isolation.
The Agent Authorization Profile (AAP) <xref target="I-D.aap-oauth-profile"/>
provides structured authorization via OAuth 2.0 but requires a
central Authorization Server. The WIMSE Execution Context Token
<xref target="I-D.nennemann-wimse-ect"/> provides execution accountability but
requires WIMSE workload identity infrastructure (SPIFFE/SPIRE).</t>

<t>This document defines the Agent Context Token (ACT), which addresses
both requirements in a single, self-contained token that requires no
shared infrastructure beyond the ability to verify asymmetric
signatures. The word "Context" in the name reflects what the token
carries: the complete invocation context of an agent — DAG references,
task metadata, capabilities, delegation chain, and oversight claims
— bound together in one cryptographically verifiable envelope. ACT
is positioned as the general agent context primitive, with the
WIMSE Execution Context Token (ECT) <xref target="I-D.nennemann-wimse-ect"/> as a
sibling profile specialized for workload-identity-bound execution
contexts in WIMSE deployments.</t>

<section anchor="problem-statement"><name>Problem Statement</name>

<t>Cross-organizational agent federation today faces a bootstrapping
problem: deploying shared OAuth infrastructure or a common SPIFFE
trust domain requires organizational agreement before the first
message is exchanged. In practice this means either:</t>

<t>(a) agents operate without cryptographic authorization or audit
    trails, relying on application-layer access control only; or</t>

<t>(b) organizations adopt one party's identity infrastructure, creating
    a hub-and-spoke dependency that contradicts the decentralized
    nature of agent networks.</t>

<t>ACT solves this by making pre-shared keys the mandatory-to-implement
trust baseline — two agents can begin a secure, auditable interaction
with nothing more than an out-of-band key exchange — while providing
a clean upgrade path to PKI or DID-based trust without changing the
token format.</t>

</section>
<section anchor="design-goals"><name>Design Goals</name>

<t><list style="symbols">
  <t><strong>G1 — Zero infrastructure baseline</strong>: ACT <bcp14>MUST</bcp14> be deployable with
no shared servers, no common identity provider, and no transparency
service.</t>
  <t><strong>G2 — Single token lifecycle</strong>: Authorization and accountability
<bcp14>MUST</bcp14> be expressed in the same token format to prevent
authorization-accountability gaps.</t>
  <t><strong>G3 — Peer-to-peer delegation</strong>: Delegation chains <bcp14>MUST</bcp14> be
verifiable without contacting an Authorization Server, using
cryptographic chaining of agent signatures.</t>
  <t><strong>G4 — DAG-native causal ordering</strong>: Workflows with parallel
branches and fan-in dependencies <bcp14>MUST</bcp14> be expressible natively,
without flattening to a linear chain.</t>
  <t><strong>G5 — Cross-organizational interoperability</strong>: ACTs issued by
agents in different trust domains <bcp14>MUST</bcp14> be verifiable by any
participant holding the issuing agent's public key.</t>
  <t><strong>G6 — Regulatory applicability</strong>: ACT <bcp14>MUST</bcp14> provide sufficient
evidence for audit requirements in DORA <xref target="DORA"/>, EU AI Act
Article 12 <xref target="EUAIA"/>, and IEC 62304 <xref target="IEC62304"/> without requiring
additional log formats.</t>
  <t><strong>G7 — Upgrade path</strong>: The trust model <bcp14>MUST</bcp14> support migration from
pre-shared keys to PKI or DID without breaking existing ACT chains.</t>
</list></t>

</section>
<section anchor="non-goals"><name>Non-Goals</name>

<t>The following are explicitly out of scope:</t>

<t><list style="symbols">
  <t>Defining internal AI model behavior or decision logic.</t>
  <t>Replacing organizational security policies or procedures.</t>
  <t>Defining storage formats for audit ledgers.</t>
  <t>Specifying token revocation infrastructure (deployments <bcp14>MAY</bcp14> use
existing mechanisms such as <xref target="RFC7009"/> for this purpose).</t>
  <t>Providing non-equivocation guarantees in standalone mode (see
<xref target="equivocation"/> for the equivocation discussion and optional
transparency anchoring).</t>
</list></t>

</section>
<section anchor="relationship-to-related-work"><name>Relationship to Related Work</name>

<t><strong>AAP <xref target="I-D.aap-oauth-profile"/></strong>: ACT addresses the same authorization
problem as AAP but does not require an Authorization Server. ACT
delegation is peer-to-peer via cryptographic signature chaining;
AAP delegation requires OAuth Token Exchange <xref target="RFC8693"/> against a
central AS. ACT is not a profile of AAP; it is an
infrastructure-independent alternative for the same problem class.</t>

<t><strong>WIMSE ECT <xref target="I-D.nennemann-wimse-ect"/></strong>: ACT addresses the same
execution accountability problem as the WIMSE Execution Context Token
but does not require WIMSE workload identity infrastructure. ACT is
not a profile of WIMSE; it is deployable in environments without
SPIFFE/SPIRE. In environments where WIMSE is deployed, ACT <bcp14>MAY</bcp14> be
carried alongside WIMSE tokens to augment accountability with
authorization provenance.</t>

<t><strong>SCITT <xref target="I-D.ietf-scitt-architecture"/></strong>: For deployments requiring
non-equivocation guarantees (see <xref target="equivocation"/>), ACT execution
records <bcp14>MAY</bcp14> be anchored to a SCITT Transparency Service as a Layer 2
mechanism. This is <bcp14>OPTIONAL</bcp14> and not required for basic ACT operation.
Note: The SCITT architecture draft is currently in AUTH48 (RFC
Editor queue) at version -22 and is about to become an RFC; readers
should use the RFC number once assigned.</t>

<section anchor="concurrent-agent-authorization-proposals"><name>Concurrent Agent Authorization Proposals</name>

<t>Several concurrent proposals in the IETF and academic communities
address overlapping portions of the agent authorization problem
space. This subsection situates ACT relative to those proposals.
Protocol-layer comparison of linear versus DAG delegation
structure is deferred to <xref target="dag-vs-linear"/>; the summaries below focus
on scope and deployability.</t>

<t><strong>AIP / IBCTs <xref target="AIP-IBCT"/></strong>: The Agent Interaction Protocol proposes
Interaction-Bound Capability Tokens in two modes: compact signed
JWTs for single-hop invocation and Biscuit/Datalog tokens for
multi-hop delegation, motivated by a survey of approximately 2,000
Model Context Protocol servers that found no authorization
enforcement. ACT addresses the same problem class but relies
exclusively on JWT/JOSE throughout (no Biscuit or Datalog
dependency), defines an explicit two-phase lifecycle separating
authorization (Mandate) from proof-of-execution (Record), and
supports DAG delegation structure. IBCTs are modeled as append-only
chains at the protocol layer; ACT operates at the authorization
graph layer with revocable lifecycle states.</t>

<t><strong>SentinelAgent <xref target="SentinelAgent"/></strong>: SentinelAgent defines a formal
Delegation Chain Calculus with seven verifiable properties, a TLA+
mechanization, and reports 100% true-positive and 0% false-positive
rates against the DelegationBench v4 benchmark. It addresses the
same accountability question as ACT — namely, which principal
authorized a given chain of actions. The differentiator is
deployment substrate: SentinelAgent expresses its guarantees in a
domain-specific formal calculus, whereas ACT encodes the same
invariants in IETF-standard JWT infrastructure (RFC 7519, RFC 7515,
RFC 8032) already deployable in existing OAuth- and JOSE-aware
stacks.</t>

<t><strong>Agentic JWT <xref target="AgenticJWT"/></strong>: Agentic JWT derives a per-agent
identity as a one-way hash of the agent's prompt, registered tools,
and configuration, and chains delegation assertions across
invocations. It is the closest prior-art JWT-based construction
for agentic delegation. ACT differs in that it adds an explicit
two-phase lifecycle — separating the authorization mandate from
the proof-of-execution record — and expresses delegation as a DAG
via the array-valued <spanx style="verb">pred</spanx> claim rather than a strictly linear
chain.</t>

<t><strong>OAuth Transaction Tokens for Agents
<xref target="I-D.oauth-transaction-tokens-for-agents"/></strong>: This draft
extends OAuth Transaction Tokens with an <spanx style="verb">actchain</spanx> claim (an
ordered delegation array), an <spanx style="verb">agentic_ctx</spanx> claim conveying intent
and constraints, and flow-type markers distinguishing interactive
from autonomous invocations. It is complementary to ACT at the
OAuth layer. The primary differentiators are topology and
infrastructure dependency: Transaction Tokens for Agents presume
an OAuth Authorization Server and use a linear <spanx style="verb">actchain</spanx>, whereas
ACT operates peer-to-peer without any AS and uses a DAG-valued
<spanx style="verb">pred</spanx>. A detailed differencing document is referenced in
<xref target="security-considerations"/>.</t>

<t><strong>Helixar Delegation Protocol (HDP)
<xref target="I-D.helixar-hdp-agentic-delegation"/></strong>: HDP specifies
Ed25519 signatures over RFC 8785-canonicalized JSON, an
append-only linear delegation chain with session binding, and
offline verification. ACT addresses the same problem but is
encoded in JWT/JOSE (aligning with the broader IETF token
ecosystem) rather than raw canonical JSON, and its <spanx style="verb">pred</spanx> claim
admits DAG topologies rather than strictly linear chains.</t>

<t><strong>SCITT Profile for AI Agent Execution Records
<xref target="I-D.emirdag-scitt-ai-agent-execution"/></strong>: This draft
defines a SCITT profile in which AgentInteractionRecord (AIR)
payloads are carried as COSE_Sign1 statements anchored to a
SCITT Transparency Service. It is highly complementary to ACT:
where ACT defines the two-phase lifecycle token issued and
consumed by agents at runtime, the SCITT AI Agent Execution
draft defines the payload format suitable for long-term anchoring.
Implementations that anchor Phase 2 ACTs to SCITT
(<xref target="security-considerations"/>) <bcp14>SHOULD</bcp14> consider the AIR payload
structure defined in that draft as the canonical encoding for
anchored records.</t>

</section>
</section>
<section anchor="applicability"><name>Applicability</name>

<t>ACT is designed as a general-purpose primitive for AI agent
authorization and execution accountability. While a sibling
specification <xref target="I-D.nennemann-wimse-ect"/> profiles execution context
tokens specifically for the WIMSE working group's workload identity
infrastructure, ACT operates without any shared identity plane. This
section identifies deployment contexts where ACT applies independently
of WIMSE, and clarifies how ACT complements — rather than competes
with — ecosystem-specific agent protocols.</t>

<section anchor="model-context-protocol-mcp-tool-use-flows"><name>Model Context Protocol (MCP) Tool-Use Flows</name>

<t>The Model Context Protocol <xref target="MCP-SPEC"/> defines a client-server
interface by which LLM hosts invoke external tools via structured
JSON-RPC calls. MCP 2025-11-25 mandates OAuth 2.1 for transport-layer
authentication, but provides no mechanism for carrying per-invocation
authorization constraints or for producing a tamper-evident record
of what arguments were passed and what result was returned.</t>

<t>ACT addresses this gap as follows: when an MCP host is about to
dispatch a tool call on behalf of an agent, it <bcp14>SHOULD</bcp14> issue a Phase 1
ACT Mandate encoding the permitted tool name (e.g., as a capability
constraint), the declaring scope, and any parameter-level constraints
applicable to that invocation. The MCP server, upon receiving the
request, <bcp14>MAY</bcp14> validate the ACT Mandate and, upon completing the tool
execution, <bcp14>SHOULD</bcp14> transition the token to Phase 2 by appending
SHA-256 hashes of the serialized input arguments and the JSON
response, then re-sign. The resulting Phase 2 ACT constitutes an
unforgeable record that a specific tool was called with specific
arguments and returned a specific result, independently of MCP's
OAuth layer.</t>

<t>This integration requires no modification to MCP transport; the ACT
<bcp14>SHOULD</bcp14> be carried in the <spanx style="verb">ACT-Mandate</spanx> and <spanx style="verb">ACT-Record</spanx> HTTP headers
defined in <xref target="http-header-transport"/> of this document.</t>

</section>
<section anchor="openai-agents-sdk-and-function-calling"><name>OpenAI Agents SDK and Function Calling</name>

<t>The OpenAI Agents SDK <xref target="OPENAI-AGENTS-SDK"/> enables composition of
agents via handoffs — structured transfers of control from one agent
to another, each potentially invoking registered function tools. The
SDK provides no built-in mechanism for a receiving agent to verify
that the handoff was authorized by a named principal, nor for the
invoking agent to produce a verifiable record of what functions it
called.</t>

<t>ACT is applicable at the handoff boundary: the orchestrating agent
<bcp14>SHOULD</bcp14> issue a Phase 1 ACT Mandate to the receiving agent at the
moment of handoff, encoding the permitted function set as
capability constraints and the maximum privilege the receiving agent
<bcp14>MAY</bcp14> exercise. The receiving agent <bcp14>SHOULD</bcp14> attach its Phase 2 ACT
Record to any callback or downstream response, providing the
orchestrator with cryptographic evidence of the actions taken. In
multi-turn chains involving multiple handoffs, the DAG linkage
(<xref target="dag-structure"/>) allows each handoff to be expressed as a
parent-child edge, preserving the full causal ordering of the agent
invocation sequence.</t>

<t>Implementations that use the OpenAI function calling API directly,
without the Agents SDK, <bcp14>MAY</bcp14> apply ACT at the application layer: the
calling process issues a Phase 1 ACT before the function call
parameter block is finalized, and the receiving function handler
returns a Phase 2 ACT alongside its JSON result.</t>

</section>
<section anchor="langgraph-and-langchain-agent-graphs"><name>LangGraph and LangChain Agent Graphs</name>

<t>LangGraph <xref target="LANGGRAPH"/> models agent workflows as typed StateGraphs in
which nodes represent agent invocations or tool calls and edges
represent conditional transitions. The DAG structure of ACT
(<xref target="dag-structure"/>) is a natural fit for this model: each LangGraph
node that performs an observable action corresponds to exactly one
ACT task identifier (<spanx style="verb">tid</spanx>), and directed edges in the LangGraph
correspond to <spanx style="verb">pred</spanx> (predecessor) references in successor ACTs.</t>

<t>ACT is applicable at the node boundary: when a LangGraph node
dispatches a sub-agent or invokes a tool with side effects, it <bcp14>SHOULD</bcp14>
issue a Phase 1 ACT Mandate encoding the node's permitted actions
before any external call is made. Upon transition out of the node,
a Phase 2 ACT Record <bcp14>SHOULD</bcp14> be produced and attached to the
LangGraph state object alongside the node's output. Downstream nodes
that fan-in from multiple predecessors <bcp14>MAY</bcp14> retrieve the set of parent
ACT identifiers from the shared state to populate their <spanx style="verb">pred</spanx> array,
thereby expressing LangGraph's fan-in semantics within the ACT DAG
without any additional infrastructure.</t>

<t>In contrast to LangGraph's built-in state audit trail, which is
mutable in-process memory, Phase 2 ACTs are cryptographically signed
and portable: they can be exported from a LangGraph run and
submitted to an external audit ledger, satisfying compliance
requirements that cannot be met by in-process logging alone.</t>

</section>
<section anchor="google-agent2agent-a2a-protocol"><name>Google Agent2Agent (A2A) Protocol</name>

<t>The Agent2Agent protocol <xref target="A2A-SPEC"/> defines a task-oriented JSON-RPC
interface for inter-agent communication, with authentication
delegated to OAuth 2.0 or API key schemes declared in each agent's
Agent Card. A2A provides no mechanism for a receiving agent to
verify the authorization provenance of a task request beyond the
transport-layer credential, and produces no token that represents
the execution of the task in a verifiable, portable form.</t>

<t>ACT is applicable as a session-layer accountability complement to
A2A: a client agent <bcp14>SHOULD</bcp14> include a Phase 1 ACT Mandate in the
<spanx style="verb">metadata</spanx> field of the A2A Task object, encoding the task type as
a capability constraint and the delegating agent's identity as the
ACT issuer. The receiving agent <bcp14>SHOULD</bcp14> validate the Mandate before
beginning task execution and <bcp14>SHOULD</bcp14> return a Phase 2 ACT Record
as an artifact in the A2A TaskResult, enabling the client agent to
retain cryptographic proof of what was executed on its behalf.</t>

<t>This integration does not require modification to A2A's transport or
authentication scheme; ACT and A2A's OAuth credentials operate at
independent layers and are not redundant. A2A's credential answers
"is this client permitted to contact this server?"; the ACT Mandate
answers "is this agent permitted to request this specific task
under these constraints?".</t>

</section>
<section anchor="enterprise-orchestration-without-wimse-crewai-autogen"><name>Enterprise Orchestration Without WIMSE (CrewAI, AutoGen)</name>

<t>Enterprise orchestration frameworks such as CrewAI <xref target="CREWAI"/> and
AutoGen <xref target="AUTOGEN"/> deploy multi-agent systems within a single
organizational boundary, typically without SPIFFE/SPIRE workload
identity infrastructure. In these environments, OAuth Authorization
Servers are often unavailable or impractical to deploy for
intra-process agent communication.</t>

<t>ACT is applicable in this context via its Tier 1 (pre-shared key)
trust model (<xref target="tier1"/>): each agent role in a CrewAI Crew or
AutoGen ConversableAgent graph is assigned an Ed25519 keypair at
instantiation time. The orchestrating agent issues Phase 1 Mandates
to worker agents before delegating tasks, constraining each worker
to only the tools and actions relevant to its role. Worker agents
produce Phase 2 Records on task completion. The resulting ACT chain
is exportable as a structured audit trail that satisfies the
per-action logging requirements of DORA <xref target="DORA"/> and EU AI Act
Article 12 <xref target="EUAIA"/> without requiring shared infrastructure beyond
the ability to exchange public keys at deployment time.</t>

<t>Implementations <bcp14>SHOULD NOT</bcp14> use ACT's self-assertion mode (where an
agent issues and records its own mandate without external sign-off)
in regulated workflows; at minimum, the orchestrating agent <bcp14>MUST</bcp14>
sign the initial Mandate so that accountability is anchored to a
principal outside the executing agent.</t>

</section>
<section anchor="relationship-to-wimse-ect"><name>Relationship to WIMSE ECT</name>

<t>Where WIMSE infrastructure is deployed, ACT and the WIMSE Execution
Context Token <xref target="I-D.nennemann-wimse-ect"/> serve complementary and
non-overlapping functions. The ECT records workload-level execution
in WIMSE terms — which SPIFFE workload executed, in which trust
domain, against which service. ACT records the authorization
provenance — which agent was permitted to request which action,
under what capability constraints, by whose authority — and
transitions that authorization record into an execution record upon
task completion.</t>

<t>In mixed environments, both tokens <bcp14>SHOULD</bcp14> be carried simultaneously:
the <spanx style="verb">Workload-Identity</spanx> header carries the WIMSE ECT; the
<spanx style="verb">ACT-Record</spanx> header carries the ACT. Verifiers <bcp14>MAY</bcp14> correlate the
two by matching the ACT <spanx style="verb">tid</spanx> claim against application-layer
identifiers present in the ECT's task context. Neither token is a
profile or extension of the other; they operate at different
abstraction layers and their co-presence is additive.</t>

</section>
</section>
</section>
<section anchor="conventions-and-definitions"><name>Conventions and Definitions</name>

<t>The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
"<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as
described in BCP 14 <xref target="RFC2119"/> <xref target="RFC8174"/> when, and only when, they
appear in all capitals, as shown here.</t>

<?line -18?>

<t><strong>Agent</strong>: An autonomous software entity that executes tasks, issues
ACTs as mandates for sub-agents, and produces ACTs as execution
records of its own actions.</t>

<t><strong>Authorization Mandate</strong>: An ACT in Phase 1, encoding what an agent
is permitted to do, under what constraints, and by whose authority.</t>

<t><strong>Execution Record</strong>: An ACT in Phase 2, encoding what an agent
actually did, including cryptographic hashes of inputs and outputs
and causal links to predecessor tasks.</t>

<t><strong>Directed Acyclic Graph (DAG)</strong>: A graph structure representing task
dependency ordering where edges are directed and no cycles exist. Used
by ACT to model causal relationships between tasks in a workflow.</t>

<t><strong>Delegation Chain</strong>: A cryptographically verifiable sequence of ACT
issuances from a root authority through one or more agents, each
signing a new ACT that reduces privileges relative to the one it
received.</t>

<t><strong>Trust Tier</strong>: A level of key management infrastructure used to
establish the public key of an ACT issuer. Tiers range from
pre-shared keys (Tier 1, mandatory) to PKI (Tier 2) and DIDs
(Tier 3).</t>

<t><strong>Workflow</strong>: A set of related tasks, identified by a shared <spanx style="verb">wid</spanx>
claim, forming a single logical unit of work.</t>

</section>
<section anchor="act-lifecycle"><name>ACT Lifecycle</name>

<t>An ACT has a two-phase lifecycle. The same token format is used in
both phases; the presence or absence of execution claims determines
which phase a token represents.</t>

<t>A token is a <strong>Phase 2 Execution Record</strong> if and only if the claim
<spanx style="verb">exec_act</spanx> is present. A token that does not contain <spanx style="verb">exec_act</spanx> is
a <strong>Phase 1 Authorization Mandate</strong>. Verifiers <bcp14>MUST</bcp14> determine the
phase before applying verification rules, and <bcp14>MUST</bcp14> reject a token
that is presented in the wrong phase for the operation being
performed.</t>

<section anchor="phase-1-authorization-mandate"><name>Phase 1: Authorization Mandate</name>

<t>In Phase 1, an ACT is created by a delegating agent (or a human
operator) to authorize a target agent to perform a specific task. The
token carries:</t>

<t><list style="symbols">
  <t>The identity of the issuing agent and the target agent.</t>
  <t>The capabilities granted, with associated constraints.</t>
  <t>Human oversight requirements for high-impact actions.</t>
  <t>The delegation provenance (who authorized the issuer to delegate).</t>
  <t>A task identifier and declared purpose.</t>
</list></t>

<t>The Phase 1 ACT is signed by the issuing agent using its private key.
The target agent receives the ACT and uses it as a bearer mandate —
evidence that it is authorized to proceed.</t>

<t>Phase 1 ACTs are short-lived. Implementations <bcp14>SHOULD</bcp14> set expiration
(<spanx style="verb">exp</spanx>) to no more than 15 minutes after issuance (<spanx style="verb">iat</spanx>) for
automated agent-to-agent workflows. Longer lifetimes <bcp14>MAY</bcp14> be used for
human-initiated mandates where the agent may not act immediately.</t>

</section>
<section anchor="phase-2-execution-record"><name>Phase 2: Execution Record</name>

<t>Upon completing the authorized task, the executing agent <bcp14>MUST</bcp14>
transition the ACT to Phase 2 by:</t>

<t><list style="numbers" type="1">
  <t>Adding the <spanx style="verb">exec_act</spanx> claim describing the action performed.</t>
  <t>Optionally adding <spanx style="verb">inp_hash</spanx> and/or <spanx style="verb">out_hash</spanx> SHA-256 hashes
of task inputs and outputs (<bcp14>RECOMMENDED</bcp14> for regulated environments).</t>
  <t>Adding the <spanx style="verb">pred</spanx> array referencing predecessor task identifiers (DAG
dependencies).</t>
  <t>Adding <spanx style="verb">exec_ts</spanx> and <spanx style="verb">status</spanx> claims.</t>
  <t>Re-signing the complete token with its own private key.</t>
</list></t>

<t>The re-signing is critical: it produces a new signature over the
combined authorization + execution claims, binding the executing
agent's cryptographic identity to both the mandate it received and
the execution it performed. This creates a single, non-repudiable
record that answers both "was this agent authorized?" and "what
did it do?"</t>

<t>Note on issuer signature preservation: re-signing replaces the
Phase 1 signature produced by the issuing agent (<spanx style="verb">iss</spanx>). The
integrity of the original mandate is preserved through the
<spanx style="verb">del.chain</spanx> mechanism: the chain entry's <spanx style="verb">sig</spanx> field is the <spanx style="verb">iss</spanx>
agent's signature over the Phase 1 ACT, and this signature remains
intact and verifiable in the Phase 2 token. For root mandates where
<spanx style="verb">del.chain</spanx> is empty, the issuer's signature is not independently
preserved in Phase 2. Deployments requiring independent
verifiability of the original mandate <bcp14>SHOULD</bcp14> retain the Phase 1
ACT separately alongside the Phase 2 record.</t>

<t>The resulting Phase 2 ACT <bcp14>SHOULD</bcp14> be submitted to an audit ledger
(<xref target="audit-ledger"/>) and <bcp14>MAY</bcp14> be sent to the next agent in the workflow
as evidence of completed prerequisites.</t>

</section>
<section anchor="lifecycle-state-machine"><name>Lifecycle State Machine</name>

<figure><artwork><![CDATA[
  [Issuer creates Phase 1 ACT]
           |
           | sign(issuer_key)
           v
    +------------------+
    |  MANDATE         |  Phase 1: Authorization Mandate
    |  (unsigned by    |  Carried as bearer token by target agent
    |   target agent)  |
    +------------------+
           |
           | Target agent executes task
           | adds exec_act, inp_hash, out_hash, pred
           | re-signs with target_agent_key
           v
    +------------------+
    |  RECORD          |  Phase 2: Execution Record
    |  (signed by      |  Submitted to ledger, passed to next agent
    |   target agent)  |
    +------------------+
           |
           | (optional) anchor to SCITT Transparency Service
           v
    +------------------+
    |  ANCHORED        |  Phase 2 + external non-equivocation
    +------------------+
]]></artwork></figure>

</section>
</section>
<section anchor="act-token-format"><name>ACT Token Format</name>

<t>An ACT is a JSON Web Token <xref target="RFC7519"/> signed as a JSON Web Signature
<xref target="RFC7515"/> using JWS Compact Serialization. All ACTs <bcp14>MUST</bcp14> use JWS
Compact Serialization to ensure they can be carried in a single HTTP
header value.</t>

<section anchor="jose-header"><name>JOSE Header</name>

<t>The ACT JOSE header <bcp14>MUST</bcp14> contain:</t>

<figure><sourcecode type="json"><![CDATA[
{
  "alg": "ES256",
  "typ": "act+jwt",
  "kid": "agent-a-key-2026-03"
}
]]></sourcecode></figure>

<t><strong>alg</strong> (<bcp14>REQUIRED</bcp14>): The digital signature algorithm. Implementations
<bcp14>MUST</bcp14> support ES256 <xref target="RFC7518"/>. EdDSA (Ed25519) <xref target="RFC8037"/> is
<bcp14>RECOMMENDED</bcp14> for new deployments due to smaller signatures and
resistance to side-channel attacks. Symmetric algorithms (HS256,
HS384, HS512) <bcp14>MUST NOT</bcp14> be used. The "alg" value <bcp14>MUST NOT</bcp14> be "none".</t>

<t><strong>typ</strong> (<bcp14>REQUIRED</bcp14>): <bcp14>MUST</bcp14> be "act+jwt" to distinguish ACTs from other
JWT types.</t>

<t><strong>kid</strong> (<bcp14>REQUIRED</bcp14>): An identifier for the signing key. In Tier 1
deployments (pre-shared keys), this is an opaque string agreed
out-of-band. In Tier 2 deployments (PKI), this is the X.509
certificate thumbprint. In Tier 3 deployments (DID), this is the
DID key fragment (e.g., <spanx style="verb">did:key:z6Mk...#key-1</spanx>).</t>

<t><strong>x5c</strong> (<bcp14>OPTIONAL</bcp14>): In Tier 2 deployments, the X.509 certificate
chain <bcp14>MAY</bcp14> be included to enable verification without out-of-band
key distribution.</t>

<t><strong>did</strong> (<bcp14>OPTIONAL</bcp14>): In Tier 3 deployments, the full DID of the
issuing agent <bcp14>MAY</bcp14> be included for resolution.</t>

</section>
<section anchor="jwt-claims-authorization-phase"><name>JWT Claims: Authorization Phase</name>

<section anchor="standard-jwt-claims"><name>Standard JWT Claims</name>

<t><strong>iss</strong> (<bcp14>REQUIRED</bcp14>): The identifier of the agent issuing the mandate.
Format depends on trust tier: an opaque string (Tier 1), an X.509
Subject DN (Tier 2), or a DID (Tier 3).</t>

<t><strong>sub</strong> (<bcp14>REQUIRED</bcp14>): The identifier of the agent authorized to act.
<bcp14>MUST</bcp14> use the same format convention as <spanx style="verb">iss</spanx>.</t>

<t><strong>aud</strong> (<bcp14>REQUIRED</bcp14>): The intended recipient(s). <bcp14>MUST</bcp14> include the
identifier of the target agent (<spanx style="verb">sub</spanx>). When an audit ledger is
deployed, <bcp14>MUST</bcp14> also include the ledger's identifier. When multiple
recipients are present, <bcp14>MUST</bcp14> be an array. Verifiers that are audit
ledgers <bcp14>MUST</bcp14> verify that their own identifier appears in <spanx style="verb">aud</spanx>.</t>

<t><strong>iat</strong> (<bcp14>REQUIRED</bcp14>): Issuance time as a NumericDate <xref target="RFC7519"/>.</t>

<t><strong>exp</strong> (<bcp14>REQUIRED</bcp14>): Expiration time. Implementations <bcp14>SHOULD</bcp14> set to
no more than 15 minutes after <spanx style="verb">iat</spanx> for automated workflows.</t>

<t><strong>jti</strong> (<bcp14>REQUIRED</bcp14>): A UUID <xref target="RFC9562"/> uniquely identifying this ACT
and, in Phase 2, the task it records. Used as the task identifier
for DAG predecessor references in <spanx style="verb">pred</spanx>.</t>

</section>
<section anchor="act-authorization-claims"><name>ACT Authorization Claims</name>

<t><strong>wid</strong> (<bcp14>OPTIONAL</bcp14>): A UUID identifying the workflow to which this
task belongs. When present, groups related ACTs and scopes <spanx style="verb">jti</spanx>
uniqueness to the workflow.</t>

<t><strong>task</strong> (<bcp14>REQUIRED</bcp14>): An object describing the authorized task:</t>

<figure><sourcecode type="json"><![CDATA[
{
  "task": {
    "purpose": "validate_patient_dosage",
    "data_sensitivity": "restricted",
    "created_by": "operator:clinical-admin-01",
    "expires_at": 1772064750
  }
}
]]></sourcecode></figure>

<t><list style="symbols">
  <t><spanx style="verb">purpose</spanx> (<bcp14>REQUIRED</bcp14>): A string describing the intended task.
Implementations <bcp14>SHOULD</bcp14> use a controlled vocabulary or reverse-
domain notation (e.g., "com.example.validate_dosage") to enable
semantic consistency checking by the receiving agent.</t>
  <t><spanx style="verb">data_sensitivity</spanx> (<bcp14>OPTIONAL</bcp14>): One of "public", "internal",
"confidential", "restricted". Receiving agents <bcp14>MUST NOT</bcp14> perform
actions that would expose data above this classification.</t>
  <t><spanx style="verb">created_by</spanx> (<bcp14>OPTIONAL</bcp14>): An identifier for the human or system
that initiated the workflow. <bcp14>SHOULD</bcp14> be pseudonymous (see
<xref target="privacy-considerations"/>).</t>
  <t><spanx style="verb">expires_at</spanx> (<bcp14>OPTIONAL</bcp14>): A NumericDate after which the task
mandate is no longer valid, independent of <spanx style="verb">exp</spanx>.</t>
</list></t>

<t><strong>cap</strong> (<bcp14>REQUIRED</bcp14>): An array of capability objects, each specifying
an action the agent is authorized to perform and the constraints
under which it may do so:</t>

<figure><sourcecode type="json"><![CDATA[
{
  "cap": [
    {
      "action": "read.patient_record",
      "constraints": {
        "patient_id_scope": "current_task_only",
        "max_records": 1,
        "data_classification_max": "restricted"
      }
    },
    {
      "action": "write.dosage_recommendation",
      "constraints": {
        "status": "draft_only"
      }
    }
  ]
}
]]></sourcecode></figure>

<t>Action names <bcp14>MUST</bcp14> conform to the ABNF grammar:</t>

<figure><artwork><![CDATA[
action-name = component *( "." component )
component   = ALPHA *( ALPHA / DIGIT / "-" / "_" )
]]></artwork></figure>

<t>Receiving agents <bcp14>MUST</bcp14> perform exact string matching on action names.
Wildcard matching is NOT part of this specification.</t>

<t>When multiple capabilities match the same action, OR semantics
apply: if ANY capability grants the action, the request is
authorized subject to that capability's constraints. When multiple
constraints exist within a single capability, AND semantics apply:
ALL constraints <bcp14>MUST</bcp14> be satisfied. When the same constraint key
appears in both a capability-level and a policy-level context, the
more restrictive value applies: lower numeric limits, narrower
allow-lists (intersection), broader block-lists (union), and
narrower time windows.</t>

<t><strong>oversight</strong> (<bcp14>OPTIONAL</bcp14>): Human oversight requirements:</t>

<figure><sourcecode type="json"><![CDATA[
{
  "oversight": {
    "requires_approval_for": ["write.publish", "execute.payment"],
    "approval_ref": "https://approval.example.com/workflow/w-123"
  }
}
]]></sourcecode></figure>

<t>When <spanx style="verb">requires_approval_for</spanx> lists an action, the receiving agent
<bcp14>MUST NOT</bcp14> execute that action autonomously. The approval mechanism
is out of scope for this specification.</t>

<t><strong>del</strong> (<bcp14>OPTIONAL</bcp14>): Delegation provenance, establishing the chain
of authority from the root mandate to this ACT. If <spanx style="verb">del</spanx> is absent,
the ACT <bcp14>MUST</bcp14> be treated as a root mandate with <spanx style="verb">depth</spanx> = 0 and
further delegation is not permitted (i.e., the receiving agent <bcp14>MUST
NOT</bcp14> issue sub-mandates based on this ACT).</t>

<figure><sourcecode type="json"><![CDATA[
{
  "del": {
    "depth": 1,
    "max_depth": 3,
    "chain": [
      {
        "delegator": "did:key:z6MkhaXgBZDvotDkL5257faiztiGiC2QtKLGpbnnEGta2doK",
        "jti": "550e8400-e29b-41d4-a716-446655440000",
        "sig": "base64url-encoded-signature-of-parent-act-hash"
      }
    ]
  }
}
]]></sourcecode></figure>

<t><list style="symbols">
  <t><spanx style="verb">depth</spanx>: The current delegation depth. 0 means this is a root
mandate issued by a human or root authority.</t>
  <t><spanx style="verb">max_depth</spanx>: The maximum permitted delegation depth. Receiving
agents <bcp14>MUST NOT</bcp14> issue sub-mandates that would exceed this depth.</t>
  <t><spanx style="verb">chain</spanx>: An array of delegation provenance records ordered from
root to immediate parent (<spanx style="verb">chain[0]</spanx> is the root authority,
<spanx style="verb">chain[depth-1]</spanx> is the direct parent of this ACT). Each entry
contains:
  <list style="symbols">
      <t><spanx style="verb">delegator</spanx>: The identifier of the agent that authorized this
delegation step (i.e., the <spanx style="verb">iss</spanx> of the parent ACT at that
depth).</t>
      <t><spanx style="verb">jti</spanx>: The <spanx style="verb">jti</spanx> of the parent ACT that authorized this
delegation step.</t>
      <t><spanx style="verb">sig</spanx>: The delegating agent's signature over the SHA-256 hash
of that parent ACT, providing cryptographic linkage without
requiring the full parent ACT to be transmitted.</t>
    </list></t>
</list></t>

<t>The <spanx style="verb">sig</spanx> field in each chain entry is the critical departure from
AAP's delegation model: rather than requiring a central AS to
validate the chain, any verifier holding the delegating agent's
public key can independently verify each step by recomputing the
hash and checking the signature.</t>

</section>
</section>
<section anchor="jwt-claims-execution-phase"><name>JWT Claims: Execution Phase</name>

<t>The following claims are added by the executing agent when
transitioning to Phase 2. Their presence distinguishes an Execution
Record from an Authorization Mandate.</t>

<t><strong>exec_act</strong> (<bcp14>REQUIRED</bcp14> in Phase 2): A string identifying the action
actually performed. <bcp14>MUST</bcp14> conform to the same ABNF grammar as
capability action names. <bcp14>MUST</bcp14> match one of the <spanx style="verb">action</spanx> values in
the <spanx style="verb">cap</spanx> array of the Phase 1 claims.</t>

<t><strong>pred</strong> (<bcp14>REQUIRED</bcp14> in Phase 2): An array of <spanx style="verb">jti</spanx> values of predecessor
tasks in the DAG. An empty array indicates a root task. Each value
<bcp14>MUST</bcp14> be the <spanx style="verb">jti</spanx> of a previously verified ACT (Phase 2) within
the same workflow (same <spanx style="verb">wid</spanx>) or the global ACT store if <spanx style="verb">wid</spanx> is
absent.</t>

<t><strong>inp_hash</strong> (<bcp14>OPTIONAL</bcp14>): The base64url encoding (without padding) of
the SHA-256 hash of the task's input data, computed over the raw
octets of the serialized input. Provides cryptographic evidence of
what data the agent processed.</t>

<t><strong>out_hash</strong> (<bcp14>OPTIONAL</bcp14>): The base64url encoding (without padding) of
the SHA-256 hash of the task's output data, using the same format
as <spanx style="verb">inp_hash</spanx>. Provides cryptographic evidence of what data the
agent produced.</t>

<t><strong>exec_ts</strong> (<bcp14>REQUIRED</bcp14> in Phase 2): A NumericDate recording the
actual time of task execution. <bcp14>MAY</bcp14> differ from <spanx style="verb">iat</spanx> when the agent
queued the mandate before execution. <bcp14>MUST</bcp14> be greater than or equal
to <spanx style="verb">iat</spanx>. <bcp14>SHOULD</bcp14> be less than or equal to <spanx style="verb">exp</spanx>; execution after
mandate expiry is possible when tasks are long-running and <bcp14>MUST NOT</bcp14>
cause automatic rejection, but implementors <bcp14>SHOULD</bcp14> log a warning.</t>

<t><strong>status</strong> (<bcp14>REQUIRED</bcp14> in Phase 2): One of "completed", "failed",
"partial". Allows audit systems to distinguish successful execution
from partial or failed attempts, which is essential for regulated
environments where failed attempts must be recorded.</t>

<t><strong>err</strong> (<bcp14>OPTIONAL</bcp14>, present when <spanx style="verb">status</spanx> is "failed" or "partial"):
An object providing error context:</t>

<figure><sourcecode type="json"><![CDATA[
{
  "err": {
    "code": "constraint_violation",
    "detail": "data_classification_max exceeded"
  }
}
]]></sourcecode></figure>

<t>Error detail <bcp14>SHOULD NOT</bcp14> reveal internal system state beyond what is
necessary for audit purposes.</t>

</section>
<section anchor="complete-examples"><name>Complete Examples</name>

<section anchor="example-phase-1-authorization-mandate"><name>Example: Phase 1 — Authorization Mandate</name>

<figure><artwork><![CDATA[
{
  "alg": "ES256",
  "typ": "act+jwt",
  "kid": "agent-clinical-key-2026-03"
}
.
{
  "iss": "did:key:z6MkhaXgBZDvotDkL5257faiztiGiC2QtKLGpbnnEGta2doK",
  "sub": "did:key:z6MknGc3omCyas4b1GmEn4xySHgLuSHxrKrUBnrhJekxZHFz",
  "aud": [
    "did:key:z6MknGc3omCyas4b1GmEn4xySHgLuSHxrKrUBnrhJekxZHFz",
    "https://ledger.hospital.example.com"
  ],
  "iat": 1772064000,
  "exp": 1772064900,
  "jti": "550e8400-e29b-41d4-a716-446655440001",

  "wid": "a0b1c2d3-e4f5-6789-abcd-ef0123456789",

  "task": {
    "purpose": "validate_treatment_recommendation",
    "data_sensitivity": "restricted",
    "created_by": "operator:clinical-admin-01"
  },

  "cap": [
    {
      "action": "read.patient_record",
      "constraints": {
        "patient_id_scope": "current_task_only",
        "max_records": 1
      }
    },
    {
      "action": "write.safety_assessment",
      "constraints": {
        "status": "draft_only"
      }
    }
  ],

  "oversight": {
    "requires_approval_for": ["write.publish_assessment"]
  },

  "del": {
    "depth": 0,
    "max_depth": 2,
    "chain": []
  }
}
]]></artwork></figure>

</section>
<section anchor="example-phase-2-execution-record-same-token-re-signed-by-target-agent"><name>Example: Phase 2 — Execution Record (same token, re-signed by target agent)</name>

<figure><artwork><![CDATA[
{
  "alg": "EdDSA",
  "typ": "act+jwt",
  "kid": "agent-safety-key-2026-03"
}
.
{
  "iss": "did:key:z6MkhaXgBZDvotDkL5257faiztiGiC2QtKLGpbnnEGta2doK",
  "sub": "did:key:z6MknGc3omCyas4b1GmEn4xySHgLuSHxrKrUBnrhJekxZHFz",
  "aud": [
    "did:key:z6MknGc3omCyas4b1GmEn4xySHgLuSHxrKrUBnrhJekxZHFz",
    "https://ledger.hospital.example.com"
  ],
  "iat": 1772064000,
  "exp": 1772064900,
  "jti": "550e8400-e29b-41d4-a716-446655440001",

  "wid": "a0b1c2d3-e4f5-6789-abcd-ef0123456789",

  "task": {
    "purpose": "validate_treatment_recommendation",
    "data_sensitivity": "restricted",
    "created_by": "operator:clinical-admin-01"
  },

  "cap": [
    {
      "action": "read.patient_record",
      "constraints": {
        "patient_id_scope": "current_task_only",
        "max_records": 1
      }
    },
    {
      "action": "write.safety_assessment",
      "constraints": {
        "status": "draft_only"
      }
    }
  ],

  "oversight": {
    "requires_approval_for": ["write.publish_assessment"]
  },

  "del": {
    "depth": 0,
    "max_depth": 2,
    "chain": []
  },

  "exec_act": "write.safety_assessment",
  "pred": ["550e8400-e29b-41d4-a716-446655440000"],
  "inp_hash": "n4bQgYhMfWWaL-qgxVrQFaO_TxsrC4Is0V1sFbDwCgg",
  "out_hash": "LCa0a2j_xo_5m0U8HTBBNBNCLXBkg7-g-YpeiGJm564",
  "exec_ts": 1772064300,
  "status": "completed"
}
]]></artwork></figure>

</section>
</section>
</section>
<section anchor="trust-model"><name>Trust Model</name>

<t>ACT defines four trust tiers. Tier 1 is mandatory-to-implement; all
others are optional upgrades. An ACT verifier <bcp14>MUST</bcp14> be able to process
ACTs from any tier it has configured. The trust tier in use is
determined by the <spanx style="verb">kid</spanx> format and the presence of <spanx style="verb">x5c</spanx> or <spanx style="verb">did</spanx>
header parameters.</t>

<section anchor="tier-0-bootstrap-tofu-trust-on-first-use"><name>Tier 0: Bootstrap (TOFU — Trust On First Use)</name>

<t>Tier 0 is NOT part of the normative trust model and <bcp14>MUST NOT</bcp14> be used
in regulated environments. It is defined here for documentation
purposes only, to describe the common bootstrapping scenario.</t>

<t>In Tier 0, the first ACT received from an agent establishes its
public key. This is equivalent to SSH TOFU behavior: an attacker
who intercepts the first message can substitute their own key. Tier 0
deployments <bcp14>MUST</bcp14> transition to Tier 1 or higher before exchanging
ACTs that carry sensitive capabilities.</t>

</section>
<section anchor="tier1"><name>Tier 1: Pre-Shared Keys (Mandatory-to-Implement)</name>

<t>In Tier 1, both parties exchange public keys out-of-band prior to
the first ACT exchange. The <spanx style="verb">kid</spanx> is an opaque string agreed during
the key exchange. Implementations <bcp14>MUST</bcp14> support Tier 1.</t>

<t>Key exchange <bcp14>MAY</bcp14> occur via any out-of-band mechanism: manual
configuration, a configuration management system, or a prior
authenticated channel. This specification does not mandate a
specific key exchange protocol.</t>

<t>Tier 1 public keys <bcp14>MUST</bcp14> be Ed25519 <xref target="RFC8037"/> or P-256 (ES256)
<xref target="RFC7518"/> keys. RSA keys <bcp14>SHOULD NOT</bcp14> be used in Tier 1 deployments due to
key size. Key rotation <bcp14>MUST</bcp14> be performed out-of-band using the same
mechanism as the initial exchange.</t>

</section>
<section anchor="tier-2-pki-x509"><name>Tier 2: PKI / X.509</name>

<t>In Tier 2, agent identity is bound to an X.509 certificate issued
by a mutually trusted Certificate Authority (CA). The <spanx style="verb">kid</spanx> is the
certificate thumbprint (SHA-256 of the DER-encoded certificate).</t>

<t>Cross-organizational ACT exchange in Tier 2 requires either:</t>

<t>(a) a mutually trusted root CA, or
(b) cross-certification between the organizations' CAs, or
(c) explicit trust anchoring (one organization's CA is added to
    the other's trust store).</t>

<t>The <spanx style="verb">x5c</spanx> JOSE header parameter <xref target="RFC7515"/> <bcp14>MAY</bcp14> carry the full
certificate chain to enable verification without out-of-band trust
store configuration.</t>

</section>
<section anchor="tier-3-decentralized-identifiers-did"><name>Tier 3: Decentralized Identifiers (DID)</name>

<t>In Tier 3, agent identity is expressed as a DID <xref target="W3C-DID"/>. The
<spanx style="verb">kid</spanx> is a DID key fragment. The <spanx style="verb">did</spanx> JOSE header parameter carries
the full DID for resolution.</t>

<t>Implementations <bcp14>SHOULD</bcp14> support at minimum <spanx style="verb">did:key</spanx> <xref target="DID-KEY"/> for
self-contained key distribution without external resolution, and
<spanx style="verb">did:web</spanx> <xref target="DID-WEB"/> for organizations that prefer DNS-anchored
identity.</t>

<t>DID resolution latency introduces a dependency on external
infrastructure. To preserve the zero-infrastructure baseline,
implementations using Tier 3 <bcp14>MAY</bcp14> cache DID Documents and <bcp14>MUST</bcp14>
specify a maximum cache TTL in their configuration.</t>

</section>
<section anchor="cross-tier-interoperability"><name>Cross-Tier Interoperability</name>

<t>A delegation chain <bcp14>MAY</bcp14> include agents operating at different trust
tiers. Each step in the chain is verified using the trust tier of
the signing agent at that step. Verifiers <bcp14>MUST NOT</bcp14> reject a chain
solely because it mixes trust tiers, but <bcp14>MAY</bcp14> apply stricter
policy for chains that include Tier 0 or Tier 1 steps when
exchanging sensitive capabilities.</t>

</section>
</section>
<section anchor="delegation-chain"><name>Delegation Chain</name>

<t>ACT delegation is peer-to-peer: no Authorization Server is involved.
Delegation is expressed as a cryptographically verifiable chain of
ACT issuances, where each step reduces privileges relative to the
previous step.</t>

<section anchor="peer-to-peer-delegation"><name>Peer-to-Peer Delegation</name>

<t>When Agent A authorizes Agent B to perform a sub-task, Agent A:</t>

<t><list style="numbers" type="1">
  <t>Creates a new ACT with <spanx style="verb">sub</spanx> set to Agent B's identifier.</t>
  <t>Sets <spanx style="verb">cap</spanx> to a subset of A's own authorized capabilities,
with constraints at least as restrictive as those in A's mandate.</t>
  <t>Sets <spanx style="verb">del.depth</spanx> to A's own <spanx style="verb">del.depth + 1</spanx>.</t>
  <t>Sets <spanx style="verb">del.max_depth</spanx> to no more than the <spanx style="verb">del.max_depth</spanx> value
in A's own mandate.</t>
  <t>Adds a chain entry containing A's identifier as <spanx style="verb">delegator</spanx>,
the <spanx style="verb">jti</spanx> of A's own mandate, and a <spanx style="verb">sig</spanx> value computed as:  <vspace blankLines='1'/>
    <figure><artwork><![CDATA[
sig = Sign(A.private_key, SHA-256(canonical_ACT_phase1_bytes))
]]></artwork></figure>
  <vspace blankLines='1'/>
where <spanx style="verb">canonical_ACT_phase1_bytes</spanx> is the UTF-8 encoded bytes
of the JWS Compact Serialization of A's Phase 1 ACT.</t>
  <t>Signs the new ACT with A's private key.</t>
</list></t>

</section>
<section anchor="privilege-reduction-requirements"><name>Privilege Reduction Requirements</name>

<t>When issuing a delegated ACT, the issuing agent <bcp14>MUST</bcp14> reduce
privileges by one or more of:</t>

<t><list style="symbols">
  <t>Removing capabilities (sub-set of parent capabilities only).</t>
  <t>Adding stricter constraints (lower rate limits, narrower domains,
shorter time windows, lower data classification ceiling).</t>
  <t>Reducing token lifetime (<spanx style="verb">exp</spanx> closer to <spanx style="verb">iat</spanx>).</t>
  <t>Reducing <spanx style="verb">del.max_depth</spanx>.</t>
</list></t>

<t>The issuing agent <bcp14>MUST NOT</bcp14> grant capabilities not present in its
own mandate. Capability escalation via delegation is prohibited and
<bcp14>MUST</bcp14> be detected and rejected by verifiers.</t>

<t>For well-known numeric constraints (e.g., <spanx style="verb">max_records</spanx>,
<spanx style="verb">max_requests_per_hour</spanx>), "more restrictive" means a numerically
lower or equal value. For well-known enumerated constraints
(e.g., <spanx style="verb">data_sensitivity</spanx>), "more restrictive" means a value that
is equal or higher in the defined ordering
("public" &lt; "internal" &lt; "confidential" &lt; "restricted").
For unknown or domain-specific constraint keys, verifiers <bcp14>MUST</bcp14>
treat the constraint as non-comparable and <bcp14>MUST</bcp14> reject the
delegation unless the delegated constraint value is byte-for-byte
identical to the parent constraint value.</t>

</section>
<section anchor="delegation-verification"><name>Delegation Verification</name>

<t>A verifier receiving a delegated ACT <bcp14>MUST</bcp14>:</t>

<t><list style="numbers" type="1">
  <t>Verify the ACT's own signature (<xref target="auth-verification"/>).</t>
  <t>For each entry in <spanx style="verb">del.chain</spanx>, in order from index 0 to
<spanx style="verb">del.depth - 1</spanx>:
a. Retrieve the public key for <spanx style="verb">entry.delegator</spanx>.
b. Verify that <spanx style="verb">entry.sig</spanx> is a valid signature over the SHA-256
   hash of the referenced parent ACT (identified by <spanx style="verb">entry.jti</spanx>).
c. Verify that the capabilities in the current ACT are a subset
   of the capabilities in the parent ACT, per the constraint
   comparison rules in <xref target="privilege-reduction-requirements"/>.</t>
  <t>Verify that <spanx style="verb">del.depth</spanx> does not exceed <spanx style="verb">del.max_depth</spanx>.</t>
  <t>Verify that <spanx style="verb">del.chain</spanx> length equals <spanx style="verb">del.depth</spanx>.</t>
</list></t>

<t>If any step fails, the ACT <bcp14>MUST</bcp14> be rejected.</t>

</section>
</section>
<section anchor="dag-structure"><name>DAG Structure and Causal Ordering</name>

<t>ACTs in Phase 2 form a DAG over the <spanx style="verb">pred</spanx> (predecessor) claim. The DAG
encodes causal dependencies: a task <bcp14>MAY</bcp14> NOT begin before all its
parent tasks are completed.</t>

<section anchor="dag-validation"><name>DAG Validation</name>

<t>When processing a Phase 2 ACT, implementations <bcp14>MUST</bcp14>:</t>

<t><list style="numbers" type="1">
  <t><strong>Uniqueness</strong>: Verify the <spanx style="verb">jti</spanx> is unique within the workflow
(<spanx style="verb">wid</spanx>) or globally if <spanx style="verb">wid</spanx> is absent.</t>
  <t><strong>Predecessor Existence</strong>: Verify every <spanx style="verb">jti</spanx> in <spanx style="verb">pred</spanx> corresponds to
a Phase 2 ACT available in the ACT store or audit ledger.</t>
  <t><strong>Temporal Ordering</strong>: Verify that for each parent:
<spanx style="verb">parent.exec_ts &lt; child.exec_ts + clock_skew_tolerance</spanx>
(<bcp14>RECOMMENDED</bcp14> tolerance: 30 seconds). Causal ordering is
primarily enforced by DAG structure, not timestamps.</t>
  <t><strong>Acyclicity</strong>: Following parent references <bcp14>MUST NOT</bcp14> lead back
to the current ACT's <spanx style="verb">jti</spanx>. Implementations <bcp14>MUST</bcp14> enforce a
maximum ancestor traversal limit (<bcp14>RECOMMENDED</bcp14>: 10,000 nodes).</t>
  <t><strong>Capability Consistency</strong>: Verify that <spanx style="verb">exec_act</spanx> matches one
of the <spanx style="verb">action</spanx> values in the <spanx style="verb">cap</spanx> array from Phase 1.</t>
</list></t>

</section>
<section anchor="root-tasks-and-fan-in"><name>Root Tasks and Fan-in</name>

<t>A root task has <spanx style="verb">pred = []</spanx>. A workflow <bcp14>MAY</bcp14> have multiple root tasks
representing parallel branches with no shared predecessor.</t>

<t>Fan-in — a task with multiple parents — is expressed naturally:</t>

<figure><sourcecode type="json"><![CDATA[
{
  "pred": [
    "550e8400-e29b-41d4-a716-446655440001",
    "550e8400-e29b-41d4-a716-446655440002"
  ]
}
]]></sourcecode></figure>

<t>This indicates the current task depends on the completion of both
referenced parent tasks, which <bcp14>MAY</bcp14> have been executed in parallel
by different agents.</t>

</section>
<section anchor="dag-vs-linear"><name>DAG vs Linear Delegation Chains</name>

<t>Several concurrent proposals for agent authorization model delegation
as an ordered, linear chain of tokens or principals. Examples include
the <spanx style="verb">actchain</spanx> claim of
<xref target="I-D.oauth-transaction-tokens-for-agents"/>, the Agentic JWT
construction of <xref target="AgenticJWT"/>, the AIP / Interaction-Bound Context Token
(IBCT) model of <xref target="AIP-IBCT"/>, and the delegation record defined in
<xref target="I-D.helixar-hdp-agentic-delegation"/>. In each of these
designs, the trail from the originator to the final executor is
represented as an ordered array recording one predecessor per hop.</t>

<section anchor="what-linear-chains-express-well"><name>What Linear Chains Express Well</name>

<t>Linear chains are a natural fit for simple sequential delegation:
agent A delegates to agent B, which delegates to agent C. The chain
records the history of that single hand-off in order, and verifiers
can walk from the current holder back to the originator without
branching. For interactive user-to-agent-to-service flows, where each
step has exactly one predecessor, a linear chain is both sufficient
and compact.</t>

</section>
<section anchor="limitations-of-linear-chains"><name>Limitations of Linear Chains</name>

<t>Agentic workflows in practice are rarely purely linear. Planner
agents dispatch parallel sub-tasks; synthesizer agents consume
results from multiple independent branches; tool calls execute
concurrently and their outputs are merged. A linear chain cannot
faithfully represent the following common topologies:</t>

<t><list style="symbols">
  <t><strong>Fork</strong>: A single task spawns multiple independent sub-tasks. A
linear chain cannot express that two concurrent sub-executions
share a common parent authorization but are otherwise
independent; each sub-task would either omit its siblings or
fabricate a false ordering between them.</t>
  <t><strong>Join (fan-in)</strong>: A task whose output depends on results from
several predecessors has no single prior hop. Linear chains
cannot express multiple-parent relationships without either
collapsing parallel branches into an arbitrary order or
duplicating records.</t>
  <t><strong>Diamond dependencies</strong>: A planner dispatches parallel work and
later synthesizes the results. The synthesis step depends on
every branch, and all branches depend on the same planner.
This diamond shape requires a DAG; a linear chain forces the
verifier to pick one branch and discard the others.</t>
  <t><strong>Cross-chain references</strong>: When two independently authorized
chains produce outputs that are later combined (e.g., a shared
cache lookup and a fresh retrieval), linear chains force a
single history and cannot record that the combined result has
two distinct provenances.</t>
</list></t>

</section>
<section anchor="acts-dag-approach"><name>ACT's DAG Approach</name>

<t>As specified in <xref target="jwt-claims-execution-phase"/>, the <spanx style="verb">pred</spanx> claim is
an array of parent <spanx style="verb">jti</spanx> values rather than a single scalar. This
allows an ACT to record:</t>

<t><list style="symbols">
  <t>Zero parents (a root task, <spanx style="verb">pred = []</spanx>);</t>
  <t>Exactly one parent (a linear chain, equivalent to the
single-predecessor designs referenced above);</t>
  <t>Multiple parents (fan-in from parallel branches); and</t>
  <t>Any acyclic shape that matches the actual execution structure.</t>
</list></t>

<t>The following example illustrates a diamond workflow. A research
agent (A) dispatches a web-search agent (B) and a code-analysis
agent (C) in parallel; both complete, and their outputs are
combined by a writer agent (D):</t>

<figure><artwork><![CDATA[
        +-----+
        |  A  |   pred = []
        +-----+
         /   \
        v     v
     +---+   +---+
     | B |   | C |   pred = [A.jti]
     +---+   +---+
        \   /
         v v
        +-----+
        |  D  |   pred = [B.jti, C.jti]
        +-----+
]]></artwork></figure>

<t>A linear <spanx style="verb">actchain</spanx> representation cannot express that D depends on
both B and C. At best, it can record one of the two parents and lose
the other, or serialize B and C into a false sequential order.</t>

</section>
<section anchor="verifiability-implications"><name>Verifiability Implications</name>

<t>With a DAG representation, an auditor holding the set of Phase 2
ACTs for a workflow can reconstruct the full execution graph, not
just one chain per final record. This matters for:</t>

<t><list style="symbols">
  <t><strong>Debugging</strong>: identifying which branch contributed an erroneous
input to a downstream synthesis.</t>
  <t><strong>Compliance</strong>: demonstrating that every input to a regulated
decision was itself authorized, not only the most recent hop.</t>
  <t><strong>Tamper-evidence</strong>: detecting that a branch has been omitted,
since the surviving siblings' <spanx style="verb">pred</spanx> arrays name the missing
predecessor by <spanx style="verb">jti</spanx>.</t>
</list></t>

</section>
<section anchor="interoperability-with-linear-chain-designs"><name>Interoperability with Linear-Chain Designs</name>

<t>ACT's DAG reduces to a linear chain in the degenerate case where
every <spanx style="verb">pred</spanx> array has length zero or one. An implementation that
requires linear-chain semantics <bcp14>MAY</bcp14> treat such ACTs as equivalent
to <spanx style="verb">actchain</spanx>-style records and ignore the fork/join capability.
The reverse reduction is not available: a linear-chain-only design
cannot represent ACT DAG topologies without loss of information.</t>

<t>ACT therefore takes the linear chain as a strict subset of its
model rather than as a competing approach. The DAG generalization
is deliberate and is motivated by the concurrent, branching nature
of real agentic executions rather than by any deficiency in the
linear-chain designs for the sequential cases they target.</t>

</section>
</section>
</section>
<section anchor="verification-procedure"><name>Verification Procedure</name>

<section anchor="auth-verification"><name>Authorization Phase Verification</name>

<t>A receiving agent <bcp14>MUST</bcp14> verify a Phase 1 ACT as follows:</t>

<t><list style="numbers" type="1">
  <t>Parse JWS Compact Serialization per <xref target="RFC7515"/>.</t>
  <t>Verify <spanx style="verb">typ</spanx> is "act+jwt".</t>
  <t>Verify <spanx style="verb">alg</spanx> is in the verifier's algorithm allowlist. The
allowlist <bcp14>MUST NOT</bcp14> include "none" or any symmetric algorithm.</t>
  <t>Retrieve the public key for <spanx style="verb">kid</spanx> per the applicable trust tier
(<xref target="trust-model"/>).</t>
  <t>Verify the JWS signature.</t>
  <t>Verify <spanx style="verb">exp</spanx> has not passed (with clock skew tolerance:
<bcp14>RECOMMENDED</bcp14> maximum 5 minutes).</t>
  <t>Verify <spanx style="verb">iat</spanx> is not unreasonably in the future (<bcp14>RECOMMENDED</bcp14>:
no more than 30 seconds ahead).</t>
  <t>Verify <spanx style="verb">aud</spanx> contains the verifier's own identifier.</t>
  <t>Verify <spanx style="verb">iss</spanx> is a trusted agent identity per local policy.</t>
  <t>Verify <spanx style="verb">sub</spanx> matches the verifier's own identifier (the agent
is the intended recipient of this mandate).</t>
  <t>Verify all required claims are present and well-formed.</t>
  <t>Verify delegation chain (<xref target="delegation-verification"/>) if
<spanx style="verb">del.chain</spanx> is non-empty.</t>
  <t>Verify capabilities are within policy limits.</t>
</list></t>

</section>
<section anchor="execution-phase-verification"><name>Execution Phase Verification</name>

<t>In addition to all Phase 1 verification steps, a verifier processing
a Phase 2 ACT <bcp14>MUST</bcp14>:</t>

<t><list style="numbers" type="1">
  <t>Verify <spanx style="verb">exec_act</spanx> is present and matches an <spanx style="verb">action</spanx> in <spanx style="verb">cap</spanx>.</t>
  <t>Verify <spanx style="verb">pred</spanx> is present and perform DAG validation
(<xref target="dag-validation"/>).</t>
  <t>Verify <spanx style="verb">exec_ts</spanx> is present and is greater than or equal to
<spanx style="verb">iat</spanx>. If <spanx style="verb">exec_ts</spanx> is after <spanx style="verb">exp</spanx>, implementations <bcp14>SHOULD</bcp14> log
a warning but <bcp14>MUST NOT</bcp14> reject the record solely on this basis.</t>
  <t>Verify <spanx style="verb">status</spanx> is present and has a valid value.</t>
  <t>Verify the re-signature was produced by the <spanx style="verb">sub</spanx> agent (the
executing agent), not the <spanx style="verb">iss</spanx> agent (the mandating agent).
This is verified by checking that the <spanx style="verb">kid</spanx> in the Phase 2 JOSE
header corresponds to the <spanx style="verb">sub</spanx> agent's public key.</t>
  <t>If <spanx style="verb">inp_hash</spanx> or <spanx style="verb">out_hash</spanx> are present, verify them against
locally available input/output data when possible.</t>
</list></t>

</section>
</section>
<section anchor="transport"><name>Transport</name>

<section anchor="http-header-transport"><name>HTTP Header Transport</name>

<t>This specification defines two HTTP header fields for ACT transport:</t>

<t><strong>ACT-Mandate</strong>: Carries a Phase 1 ACT issued by an upstream agent
or operator. Value is the JWS Compact Serialization of the ACT.</t>

<figure><artwork><![CDATA[
GET /api/safety-check HTTP/1.1
Host: safety-agent.example.com
ACT-Mandate: eyJhbGci...Phase1ACT...
]]></artwork></figure>

<t><strong>ACT-Record</strong>: Carries a Phase 2 ACT from a predecessor agent,
serving as evidence of completed prerequisites.</t>

<figure><artwork><![CDATA[
POST /api/downstream HTTP/1.1
Host: downstream-agent.example.com
ACT-Mandate: eyJhbGci...Phase1ACT...
ACT-Record: eyJhbGci...Phase2ACT...
]]></artwork></figure>

<t>Multiple <spanx style="verb">ACT-Record</spanx> header lines <bcp14>MAY</bcp14> be included when a task has
multiple completed predecessors (DAG fan-in). If any single ACT-Record
fails verification, the receiver <bcp14>MUST</bcp14> reject the entire request.</t>

</section>
<section anchor="non-http-transports"><name>Non-HTTP Transports</name>

<t>For non-HTTP transports (MCP stdio, A2A message queues, AMQP, etc.),
ACTs <bcp14>SHOULD</bcp14> be carried as a dedicated field in the transport's
metadata envelope. The field name <bcp14>SHOULD</bcp14> be <spanx style="verb">act_mandate</spanx> for Phase 1
ACTs and <spanx style="verb">act_record</spanx> for Phase 2 ACTs. Implementations <bcp14>MUST</bcp14> use the
JWS Compact Serialization form in all transports.</t>

</section>
</section>
<section anchor="audit-ledger"><name>Audit Ledger Interface</name>

<t>Phase 2 ACTs <bcp14>SHOULD</bcp14> be submitted to an immutable audit ledger.
A ledger is <bcp14>RECOMMENDED</bcp14> for regulated environments but is not
required for basic ACT operation. This specification does not
mandate a specific storage technology.</t>

<t>When an audit ledger is deployed, the implementation <bcp14>MUST</bcp14> provide:</t>

<t><list style="numbers" type="1">
  <t><strong>Append-only semantics</strong>: Once an ACT is recorded, it <bcp14>MUST NOT</bcp14>
be modified or deleted.</t>
  <t><strong>Ordering</strong>: A monotonically increasing sequence number per
recorded ACT.</t>
  <t><strong>Lookup</strong>: Efficient retrieval by <spanx style="verb">jti</spanx> value.</t>
  <t><strong>Integrity</strong>: A cryptographic commitment scheme over recorded
ACTs (e.g., hash-chaining, Merkle tree anchoring, or SCITT
registration per <xref target="I-D.ietf-scitt-architecture"/>).</t>
</list></t>

</section>
<section anchor="security-considerations"><name>Security Considerations</name>

<section anchor="threat-model"><name>Threat Model</name>

<t>ACT assumes an adversarial environment where:</t>

<t><list style="symbols">
  <t>Individual agents may be compromised.</t>
  <t>Network paths may be intercepted (mitigated by transport security).</t>
  <t>Attackers may attempt to replay valid ACTs from prior interactions.</t>
  <t>Colluding agents may attempt to fabricate execution records.</t>
  <t>Agents may attempt privilege escalation via manipulated delegation
chains.</t>
</list></t>

<t>ACT does NOT assume:</t>

<t><list style="symbols">
  <t>A trusted central authority (by design).</t>
  <t>Synchronized clocks beyond the stated skew tolerance.</t>
  <t>Availability of external network services during verification.</t>
</list></t>

</section>
<section anchor="self-assertion-limitation"><name>Self-Assertion Limitation</name>

<t>Phase 2 ACTs are self-asserted: an executing agent signs its own
execution record. A compromised agent with an intact private key can
produce Phase 2 ACTs claiming arbitrary inputs, outputs, and action
types, as long as the claimed <spanx style="verb">exec_act</spanx> matches an authorized
capability.</t>

<t>This is a fundamental limitation of self-sovereign attestation. It
is the same limitation affecting WIMSE ECT
<xref target="I-D.nennemann-wimse-ect"/>.</t>

<t>Mitigations:</t>

<t><list style="symbols">
  <t><strong>Cross-agent corroboration</strong>: A receiving agent that processes
an ACT-Record as a prerequisite independently verifies that the
claimed <spanx style="verb">out_hash</spanx> matches the data it actually received.</t>
  <t><strong>Ledger sequencing</strong>: An append-only ledger with monotonic
sequence numbers prevents retroactive insertion of fabricated
records.</t>
  <t><strong>SCITT anchoring</strong>: For high-assurance deployments, Phase 2 ACTs
<bcp14>SHOULD</bcp14> be anchored to a SCITT Transparency Service, providing
external witness that the record was submitted at a claimed time.</t>
</list></t>

</section>
<section anchor="key-compromise"><name>Key Compromise</name>

<t>If an agent's private key is compromised, an attacker can issue
arbitrary Phase 1 mandates (impersonating the agent as an issuer)
and fabricate Phase 2 records (impersonating the agent as an
executor).</t>

<t>Key compromise response:</t>

<t><list style="numbers" type="1">
  <t>The compromised agent's identifier <bcp14>MUST</bcp14> be added to all
verifiers' deny lists.</t>
  <t>In Tier 2 (PKI) deployments, the certificate <bcp14>MUST</bcp14> be revoked
via CRL or OCSP.</t>
  <t>In Tier 3 (DID) deployments, the DID Document <bcp14>MUST</bcp14> be updated
to revoke the compromised key.</t>
  <t>In Tier 1 (pre-shared key) deployments, both parties <bcp14>MUST</bcp14>
perform an out-of-band key rotation.</t>
</list></t>

<t>ACT chains that include records signed by a compromised key <bcp14>MUST</bcp14>
be treated as potentially tainted from the point of compromise.
Audit systems <bcp14>MUST</bcp14> flag all ACTs signed after the estimated
compromise time.</t>

</section>
<section anchor="replay-attack-prevention"><name>Replay Attack Prevention</name>

<t><spanx style="verb">jti</spanx> uniqueness within the applicable scope (workflow or global)
provides replay detection. Verifiers <bcp14>MUST</bcp14> reject ACTs whose <spanx style="verb">jti</spanx>
has already been seen and processed.</t>

<t><spanx style="verb">exp</spanx> provides a time-bounded replay window. Verifiers <bcp14>MUST</bcp14> reject
expired ACTs. The combination of <spanx style="verb">jti</spanx> and <spanx style="verb">exp</spanx> means that replay
detection state only needs to be maintained for the duration of token
lifetimes.</t>

</section>
<section anchor="equivocation"><name>Equivocation</name>

<t>In standalone deployment (no audit ledger, no SCITT anchoring), ACT
does NOT provide non-equivocation guarantees. A compromised agent
can maintain two valid ACT chains — presenting Phase 2 records with
different <spanx style="verb">out_hash</spanx> values to different verifiers — and both will
pass independent verification.</t>

<t><strong>Deployments claiming DORA <xref target="DORA"/> Article 10/11 compliance or EU AI
Act <xref target="EUAIA"/> Article 12 compliance <bcp14>MUST</bcp14> use one of:</strong></t>

<t>(a) A shared append-only audit ledger visible to all relevant parties,
    with cryptographic integrity (hash chaining or Merkle trees).</t>

<t>(b) SCITT anchoring <xref target="I-D.ietf-scitt-architecture"/> providing external
    Transparency Service receipts.</t>

<t>Standalone ACT provides tamper detection (a verifier can detect
modification of a record it has seen) but not split-view prevention
(a verifier cannot detect a different record shown to another
verifier).</t>

</section>
<section anchor="privilege-escalation"><name>Privilege Escalation</name>

<t>Verifiers <bcp14>MUST</bcp14> check that each step in <spanx style="verb">del.chain</spanx> reduces or
maintains (never increases) the capabilities relative to the
preceding step. Implementations <bcp14>MUST</bcp14> reject ACTs where:</t>

<t><list style="symbols">
  <t><spanx style="verb">del.depth</spanx> exceeds <spanx style="verb">del.max_depth</spanx>.</t>
  <t><spanx style="verb">cap</spanx> contains actions not present in any referenced parent ACT.</t>
  <t>Constraints in <spanx style="verb">cap</spanx> are less restrictive than those in the parent.</t>
</list></t>

</section>
<section anchor="denial-of-service"><name>Denial of Service</name>

<t>ACT verification is more computationally expensive than standard JWT
validation due to delegation chain verification and DAG traversal.</t>

<t>Mitigations:</t>

<t><list style="symbols">
  <t>Reject ACTs larger than 64KB before parsing.</t>
  <t>Enforce maximum <spanx style="verb">del.chain</spanx> length (<bcp14>RECOMMENDED</bcp14>: 10 entries).</t>
  <t>Enforce maximum DAG ancestor traversal depth (<bcp14>RECOMMENDED</bcp14>: 10,000
nodes, <xref target="dag-validation"/>).</t>
  <t>Cache verification results for recently seen <spanx style="verb">jti</spanx> values within
the token lifetime window.</t>
</list></t>

</section>
</section>
<section anchor="privacy-considerations"><name>Privacy Considerations</name>

<t>ACT tokens and audit ledger records may contain information that
identifies agents, organizations, or individuals. Implementations
<bcp14>SHOULD</bcp14> apply data minimization principles:</t>

<t><list style="symbols">
  <t><spanx style="verb">task.created_by</spanx> <bcp14>SHOULD</bcp14> use a pseudonymous identifier rather
than a personal email address or real name.</t>
  <t><spanx style="verb">task.purpose</spanx> <bcp14>SHOULD</bcp14> use a controlled vocabulary code rather
than free-text descriptions that may contain personal data.</t>
  <t><spanx style="verb">del.chain</spanx> entries reveal organizational structure. Cross-
organizational delegation chains <bcp14>SHOULD</bcp14> use Tier 3 (DID)
identifiers that do not reveal organizational affiliation.</t>
  <t><spanx style="verb">inp_hash</spanx> and <spanx style="verb">out_hash</spanx> are hashes of data, not the data
itself, and do not constitute personal data under GDPR
Article 4(1) provided the underlying data is not trivially
reversible (e.g., hashes of very short strings).</t>
</list></t>

<t>For GDPR Article 17 (right to erasure) compliance, audit ledgers
<bcp14>SHOULD</bcp14> store only ACT tokens (which contain hashes, not raw data)
and <bcp14>SHOULD</bcp14> implement crypto-shredding for any associated encrypted
payloads.</t>

</section>
<section anchor="iana-considerations"><name>IANA Considerations</name>

<section anchor="media-type-registration"><name>Media Type Registration</name>

<t>This document requests registration of the following media type:</t>

<t><list style="symbols">
  <t>Type name: application</t>
  <t>Subtype name: act+jwt</t>
  <t>Required parameters: none</t>
  <t>Encoding considerations: binary (base64url-encoded JWT)</t>
  <t>Security considerations: See <xref target="security-considerations"/>.</t>
  <t>Interoperability considerations: See <xref target="auth-verification"/>.</t>
  <t>Specification: This document.</t>
</list></t>

</section>
<section anchor="http-header-field-registration"><name>HTTP Header Field Registration</name>

<t>This document requests registration of the following HTTP header
fields in the "Hypertext Transfer Protocol (HTTP) Field Name
Registry":</t>

<t><list style="symbols">
  <t>Header field name: ACT-Mandate</t>
  <t>Applicable protocol: HTTP</t>
  <t>Status: permanent</t>
  <t>Specification: This document, <xref target="http-header-transport"/>.</t>
  <t>Header field name: ACT-Record</t>
  <t>Applicable protocol: HTTP</t>
  <t>Status: permanent</t>
  <t>Specification: This document, <xref target="http-header-transport"/>.</t>
</list></t>

</section>
<section anchor="jwt-claims-registration"><name>JWT Claims Registration</name>

<t>This document requests registration of the following claims in the
IANA "JSON Web Token Claims" registry:</t>

<texttable>
      <ttcol align='left'>Claim Name</ttcol>
      <ttcol align='left'>Description</ttcol>
      <ttcol align='left'>Reference</ttcol>
      <c>wid</c>
      <c>Workflow identifier</c>
      <c>This document</c>
      <c>task</c>
      <c>Task authorization context</c>
      <c>This document</c>
      <c>cap</c>
      <c>Capabilities with constraints</c>
      <c>This document</c>
      <c>oversight</c>
      <c>Human oversight requirements</c>
      <c>This document</c>
      <c>del</c>
      <c>Delegation provenance chain</c>
      <c>This document</c>
      <c>exec_act</c>
      <c>Executed action identifier</c>
      <c>This document</c>
      <c>pred</c>
      <c>Predecessor task identifiers (DAG)</c>
      <c>This document</c>
      <c>inp_hash</c>
      <c>SHA-256 hash of task input</c>
      <c>This document</c>
      <c>out_hash</c>
      <c>SHA-256 hash of task output</c>
      <c>This document</c>
      <c>exec_ts</c>
      <c>Actual execution timestamp</c>
      <c>This document</c>
      <c>status</c>
      <c>Execution status</c>
      <c>This document</c>
      <c>err</c>
      <c>Execution error context</c>
      <c>This document</c>
</texttable>

</section>
</section>


  </middle>

  <back>


<references title='References' anchor="sec-combined-references">

    <references title='Normative References' anchor="sec-normative-references">



<reference anchor="RFC7515">
  <front>
    <title>JSON Web Signature (JWS)</title>
    <author fullname="M. Jones" initials="M." surname="Jones"/>
    <author fullname="J. Bradley" initials="J." surname="Bradley"/>
    <author fullname="N. Sakimura" initials="N." surname="Sakimura"/>
    <date month="May" year="2015"/>
    <abstract>
      <t>JSON Web Signature (JWS) represents content secured with digital signatures or Message Authentication Codes (MACs) using JSON-based data structures. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and an IANA registry defined by that specification. Related encryption capabilities are described in the separate JSON Web Encryption (JWE) specification.</t>
    </abstract>
  </front>
  <seriesInfo name="RFC" value="7515"/>
  <seriesInfo name="DOI" value="10.17487/RFC7515"/>
</reference>
<reference anchor="RFC7517">
  <front>
    <title>JSON Web Key (JWK)</title>
    <author fullname="M. Jones" initials="M." surname="Jones"/>
    <date month="May" year="2015"/>
    <abstract>
      <t>A JSON Web Key (JWK) is a JavaScript Object Notation (JSON) data structure that represents a cryptographic key. This specification also defines a JWK Set JSON data structure that represents a set of JWKs. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and IANA registries established by that specification.</t>
    </abstract>
  </front>
  <seriesInfo name="RFC" value="7517"/>
  <seriesInfo name="DOI" value="10.17487/RFC7517"/>
</reference>
<reference anchor="RFC7518">
  <front>
    <title>JSON Web Algorithms (JWA)</title>
    <author fullname="M. Jones" initials="M." surname="Jones"/>
    <date month="May" year="2015"/>
    <abstract>
      <t>This specification registers cryptographic algorithms and identifiers to be used with the JSON Web Signature (JWS), JSON Web Encryption (JWE), and JSON Web Key (JWK) specifications. It defines several IANA registries for these identifiers.</t>
    </abstract>
  </front>
  <seriesInfo name="RFC" value="7518"/>
  <seriesInfo name="DOI" value="10.17487/RFC7518"/>
</reference>
<reference anchor="RFC7519">
  <front>
    <title>JSON Web Token (JWT)</title>
    <author fullname="M. Jones" initials="M." surname="Jones"/>
    <author fullname="J. Bradley" initials="J." surname="Bradley"/>
    <author fullname="N. Sakimura" initials="N." surname="Sakimura"/>
    <date month="May" year="2015"/>
    <abstract>
      <t>JSON Web Token (JWT) is a compact, URL-safe means of representing claims to be transferred between two parties. The claims in a JWT are encoded as a JSON object that is used as the payload of a JSON Web Signature (JWS) structure or as the plaintext of a JSON Web Encryption (JWE) structure, enabling the claims to be digitally signed or integrity protected with a Message Authentication Code (MAC) and/or encrypted.</t>
    </abstract>
  </front>
  <seriesInfo name="RFC" value="7519"/>
  <seriesInfo name="DOI" value="10.17487/RFC7519"/>
</reference>
<reference anchor="RFC8037">
  <front>
    <title>CFRG Elliptic Curve Diffie-Hellman (ECDH) and Signatures in JSON Object Signing and Encryption (JOSE)</title>
    <author fullname="I. Liusvaara" initials="I." surname="Liusvaara"/>
    <date month="January" year="2017"/>
    <abstract>
      <t>This document defines how to use the Diffie-Hellman algorithms "X25519" and "X448" as well as the signature algorithms "Ed25519" and "Ed448" from the IRTF CFRG elliptic curves work in JSON Object Signing and Encryption (JOSE).</t>
    </abstract>
  </front>
  <seriesInfo name="RFC" value="8037"/>
  <seriesInfo name="DOI" value="10.17487/RFC8037"/>
</reference>
<reference anchor="RFC9110">
  <front>
    <title>HTTP Semantics</title>
    <author fullname="R. Fielding" initials="R." role="editor" surname="Fielding"/>
    <author fullname="M. Nottingham" initials="M." role="editor" surname="Nottingham"/>
    <author fullname="J. Reschke" initials="J." role="editor" surname="Reschke"/>
    <date month="June" year="2022"/>
    <abstract>
      <t>The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document describes the overall architecture of HTTP, establishes common terminology, and defines aspects of the protocol that are shared by all versions. In this definition are core protocol elements, extensibility mechanisms, and the "http" and "https" Uniform Resource Identifier (URI) schemes.</t>
      <t>This document updates RFC 3864 and obsoletes RFCs 2818, 7231, 7232, 7233, 7235, 7538, 7615, 7694, and portions of 7230.</t>
    </abstract>
  </front>
  <seriesInfo name="STD" value="97"/>
  <seriesInfo name="RFC" value="9110"/>
  <seriesInfo name="DOI" value="10.17487/RFC9110"/>
</reference>
<reference anchor="RFC9562">
  <front>
    <title>Universally Unique IDentifiers (UUIDs)</title>
    <author fullname="K. Davis" initials="K." surname="Davis"/>
    <author fullname="B. Peabody" initials="B." surname="Peabody"/>
    <author fullname="P. Leach" initials="P." surname="Leach"/>
    <date month="May" year="2024"/>
    <abstract>
      <t>This specification defines UUIDs (Universally Unique IDentifiers) --
also known as GUIDs (Globally Unique IDentifiers) -- and a Uniform
Resource Name namespace for UUIDs. A UUID is 128 bits long and is
intended to guarantee uniqueness across space and time. UUIDs were
originally used in the Apollo Network Computing System (NCS), later
in the Open Software Foundation's (OSF's) Distributed Computing
Environment (DCE), and then in Microsoft Windows platforms.</t>
      <t>This specification is derived from the OSF DCE specification with the
kind permission of the OSF (now known as "The Open Group"). Information from earlier versions of the OSF DCE specification have
been incorporated into this document. This document obsoletes RFC
4122.</t>
    </abstract>
  </front>
  <seriesInfo name="RFC" value="9562"/>
  <seriesInfo name="DOI" value="10.17487/RFC9562"/>
</reference>
<reference anchor="RFC2119">
  <front>
    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
    <author fullname="S. Bradner" initials="S." surname="Bradner"/>
    <date month="March" year="1997"/>
    <abstract>
      <t>In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t>
    </abstract>
  </front>
  <seriesInfo name="BCP" value="14"/>
  <seriesInfo name="RFC" value="2119"/>
  <seriesInfo name="DOI" value="10.17487/RFC2119"/>
</reference>
<reference anchor="RFC8174">
  <front>
    <title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</title>
    <author fullname="B. Leiba" initials="B." surname="Leiba"/>
    <date month="May" year="2017"/>
    <abstract>
      <t>RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.</t>
    </abstract>
  </front>
  <seriesInfo name="BCP" value="14"/>
  <seriesInfo name="RFC" value="8174"/>
  <seriesInfo name="DOI" value="10.17487/RFC8174"/>
</reference>



    </references>

    <references title='Informative References' anchor="sec-informative-references">



<reference anchor="RFC7009">
  <front>
    <title>OAuth 2.0 Token Revocation</title>
    <author fullname="T. Lodderstedt" initials="T." role="editor" surname="Lodderstedt"/>
    <author fullname="S. Dronia" initials="S." surname="Dronia"/>
    <author fullname="M. Scurtescu" initials="M." surname="Scurtescu"/>
    <date month="August" year="2013"/>
    <abstract>
      <t>This document proposes an additional endpoint for OAuth authorization servers, which allows clients to notify the authorization server that a previously obtained refresh or access token is no longer needed. This allows the authorization server to clean up security credentials. A revocation request will invalidate the actual token and, if applicable, other tokens based on the same authorization grant.</t>
    </abstract>
  </front>
  <seriesInfo name="RFC" value="7009"/>
  <seriesInfo name="DOI" value="10.17487/RFC7009"/>
</reference>
<reference anchor="RFC8693">
  <front>
    <title>OAuth 2.0 Token Exchange</title>
    <author fullname="M. Jones" initials="M." surname="Jones"/>
    <author fullname="A. Nadalin" initials="A." surname="Nadalin"/>
    <author fullname="B. Campbell" initials="B." role="editor" surname="Campbell"/>
    <author fullname="J. Bradley" initials="J." surname="Bradley"/>
    <author fullname="C. Mortimore" initials="C." surname="Mortimore"/>
    <date month="January" year="2020"/>
    <abstract>
      <t>This specification defines a protocol for an HTTP- and JSON-based Security Token Service (STS) by defining how to request and obtain security tokens from OAuth 2.0 authorization servers, including security tokens employing impersonation and delegation.</t>
    </abstract>
  </front>
  <seriesInfo name="RFC" value="8693"/>
  <seriesInfo name="DOI" value="10.17487/RFC8693"/>
</reference>

<reference anchor="I-D.nennemann-wimse-ect" target="https://datatracker.ietf.org/doc/draft-nennemann-wimse-ect/">
  <front>
    <title>Execution Context Tokens for Distributed Agentic Workflows</title>
    <author fullname="Christian Nennemann">
      <organization></organization>
    </author>
    <date year="2026"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-nennemann-wimse-ect-02"/>
</reference>



<reference anchor="I-D.ietf-scitt-architecture">
   <front>
      <title>An Architecture for Trustworthy and Transparent Digital Supply Chains</title>
      <author fullname="Henk Birkholz" initials="H." surname="Birkholz">
         <organization>Fraunhofer SIT</organization>
      </author>
      <author fullname="Antoine Delignat-Lavaud" initials="A." surname="Delignat-Lavaud">
         <organization>Microsoft Research</organization>
      </author>
      <author fullname="Cedric Fournet" initials="C." surname="Fournet">
         <organization>Microsoft Research</organization>
      </author>
      <author fullname="Yogesh Deshpande" initials="Y." surname="Deshpande">
         <organization>ARM</organization>
      </author>
      <author fullname="Steve Lasker" initials="S." surname="Lasker">
         </author>
      <date day="10" month="October" year="2025"/>
      <abstract>
	 <t>   Traceability in supply chains is a growing security concern.  While
   verifiable data structures have addressed specific issues, such as
   equivocation over digital certificates, they lack a universal
   architecture for all supply chains.  This document defines such an
   architecture for single-issuer signed statement transparency.  It
   ensures extensibility, interoperability between different
   transparency services, and compliance with various auditing
   procedures and regulatory requirements.

	 </t>
      </abstract>
   </front>
   <seriesInfo name="Internet-Draft" value="draft-ietf-scitt-architecture-22"/>
   
</reference>

<reference anchor="I-D.oauth-transaction-tokens-for-agents" target="https://datatracker.ietf.org/doc/draft-oauth-transaction-tokens-for-agents/">
  <front>
    <title>Transaction Tokens for Agentic AI Systems</title>
    <author fullname="Fletcher, G.">
      <organization></organization>
    </author>
    <date year="2026"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-oauth-transaction-tokens-for-agents-06"/>
</reference>
<reference anchor="I-D.aap-oauth-profile" target="https://datatracker.ietf.org/doc/draft-aap-oauth-profile/">
  <front>
    <title>Agent Authorization Profile (AAP) for OAuth 2.0</title>
    <author fullname="Cruz, A.">
      <organization></organization>
    </author>
    <date year="2026" month="February"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-aap-oauth-profile-01"/>
</reference>
<reference anchor="I-D.helixar-hdp-agentic-delegation" target="https://datatracker.ietf.org/doc/draft-helixar-hdp-agentic-delegation/">
  <front>
    <title>Helixar Delegation Protocol (HDP) for Agentic Delegation</title>
    <author >
      <organization>Helixar</organization>
    </author>
    <date year="2026"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-helixar-hdp-agentic-delegation-00"/>
</reference>
<reference anchor="I-D.emirdag-scitt-ai-agent-execution" target="https://datatracker.ietf.org/doc/draft-emirdag-scitt-ai-agent-execution/">
  <front>
    <title>A SCITT Profile for AI Agent Execution Records</title>
    <author fullname="Emirdag">
      <organization></organization>
    </author>
    <date year="2026" month="April"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-emirdag-scitt-ai-agent-execution-00"/>
</reference>
<reference anchor="AgenticJWT" target="https://arxiv.org/abs/2509.13597">
  <front>
    <title>Agentic JWT: A JSON Web Token Profile for Delegated Agent Authorization</title>
    <author >
      <organization></organization>
    </author>
    <date year="2025"/>
  </front>
</reference>
<reference anchor="AIP-IBCT" target="https://arxiv.org/abs/2603.24775">
  <front>
    <title>AIP: Agent Interaction Protocol with Interaction-Bound Context Tokens</title>
    <author fullname="Prakash, S.">
      <organization></organization>
    </author>
    <date year="2026" month="March"/>
  </front>
</reference>
<reference anchor="SentinelAgent" target="https://arxiv.org/abs/2604.02767">
  <front>
    <title>SentinelAgent: A Formal Delegation Chain Calculus for Verifiable Agent Authorization</title>
    <author fullname="Patil">
      <organization></organization>
    </author>
    <date year="2026" month="April"/>
  </front>
</reference>
<reference anchor="MCP-SPEC" target="https://modelcontextprotocol.io/specification/2025-11-25">
  <front>
    <title>Model Context Protocol Specification</title>
    <author >
      <organization></organization>
    </author>
    <date year="2025" month="November" day="25"/>
  </front>
</reference>
<reference anchor="OPENAI-AGENTS-SDK" target="https://openai.github.io/openai-agents-python/">
  <front>
    <title>OpenAI Agents SDK</title>
    <author >
      <organization>OpenAI</organization>
    </author>
    <date />
  </front>
</reference>
<reference anchor="LANGGRAPH" target="https://langchain-ai.github.io/langgraph/">
  <front>
    <title>LangGraph Documentation</title>
    <author >
      <organization>LangChain</organization>
    </author>
    <date />
  </front>
</reference>
<reference anchor="A2A-SPEC" target="https://github.com/a2aproject/A2A">
  <front>
    <title>Agent2Agent (A2A) Protocol</title>
    <author >
      <organization>Google</organization>
    </author>
    <date />
  </front>
</reference>
<reference anchor="CREWAI" target="https://docs.crewai.com/">
  <front>
    <title>CrewAI Documentation</title>
    <author >
      <organization>CrewAI</organization>
    </author>
    <date />
  </front>
</reference>
<reference anchor="AUTOGEN" target="https://microsoft.github.io/autogen/">
  <front>
    <title>AutoGen Documentation</title>
    <author >
      <organization>Microsoft</organization>
    </author>
    <date />
  </front>
</reference>
<reference anchor="W3C-DID" target="https://www.w3.org/TR/did-core/">
  <front>
    <title>Decentralized Identifiers (DIDs) v1.0</title>
    <author fullname="Sporny, M.">
      <organization></organization>
    </author>
    <date year="2022" month="July"/>
  </front>
</reference>
<reference anchor="DID-KEY" target="https://w3c-ccg.github.io/did-method-key/">
  <front>
    <title>The did:key Method v0.7</title>
    <author fullname="Longley, D.">
      <organization></organization>
    </author>
    <date year="2021"/>
  </front>
</reference>
<reference anchor="DID-WEB" target="https://w3c-ccg.github.io/did-method-web/">
  <front>
    <title>did:web Method Specification</title>
    <author fullname="Steele, O.">
      <organization></organization>
    </author>
    <date year="2022"/>
  </front>
</reference>
<reference anchor="DORA" target="https://eur-lex.europa.eu/eli/reg/2022/2554/oj">
  <front>
    <title>Digital Operational Resilience Act (DORA), Regulation (EU) 2022/2554</title>
    <author >
      <organization>European Parliament</organization>
    </author>
    <date year="2022"/>
  </front>
</reference>
<reference anchor="EUAIA" target="https://eur-lex.europa.eu/eli/reg/2024/1689/oj">
  <front>
    <title>EU Artificial Intelligence Act, Regulation (EU) 2024/1689</title>
    <author >
      <organization>European Parliament</organization>
    </author>
    <date year="2024"/>
  </front>
</reference>
<reference anchor="IEC62304" target="https://www.iec.ch/">
  <front>
    <title>Medical device software — Software life cycle processes, IEC 62304:2006+AMD1:2015</title>
    <author >
      <organization>IEC</organization>
    </author>
    <date year="2015"/>
  </front>
</reference>


    </references>

</references>


<?line 1701?>

<section numbered="false" anchor="appendix-a-complete-json-schema"><name>Appendix A: Complete JSON Schema</name>

<t>The normative JSON Schema for ACT Phase 1 and Phase 2 tokens is
available at [TODO: reference implementation repository].</t>

</section>
<section numbered="false" anchor="appendix-b-test-vectors"><name>Appendix B: Test Vectors</name>

<section numbered="false" anchor="b1-valid-phase-1-act-root-mandate-tier-1-pre-shared-key"><name>B.1. Valid Phase 1 ACT — Root Mandate (Tier 1, Pre-Shared Key)</name>

<figure><artwork><![CDATA[
[TODO: include encoded test vector with signing key, payload,
and expected JWS Compact Serialization]
]]></artwork></figure>

</section>
<section numbered="false" anchor="b2-valid-phase-2-act-completed-execution"><name>B.2. Valid Phase 2 ACT — Completed Execution</name>

<figure><artwork><![CDATA[
[TODO: include encoded test vector demonstrating Phase 1 -> Phase 2
transition with re-signature by target agent]
]]></artwork></figure>

</section>
<section numbered="false" anchor="b3-valid-phase-2-act-fan-in-multiple-parents"><name>B.3. Valid Phase 2 ACT — Fan-in (Multiple Parents)</name>

<figure><artwork><![CDATA[
[TODO: demonstrate pred with two predecessor jti values from parallel
workflow branches]
]]></artwork></figure>

</section>
<section numbered="false" anchor="b4-invalid-act-delegation-depth-exceeded"><name>B.4. Invalid ACT — Delegation Depth Exceeded</name>

<figure><artwork><![CDATA[
[TODO: demonstrate del.depth > del.max_depth rejection]
]]></artwork></figure>

</section>
<section numbered="false" anchor="b5-invalid-act-capability-escalation"><name>B.5. Invalid ACT — Capability Escalation</name>

<figure><artwork><![CDATA[
[TODO: demonstrate rejection when delegated cap contains action
not present in parent ACT]
]]></artwork></figure>

</section>
<section numbered="false" anchor="b6-invalid-act-execact-mismatch"><name>B.6. Invalid ACT — exec_act Mismatch</name>

<figure><artwork><![CDATA[
[TODO: demonstrate rejection when exec_act does not match any
cap.action in the Phase 1 claims]
]]></artwork></figure>

</section>
</section>
<section numbered="false" anchor="appendix-c-deployment-scenarios"><name>Appendix C: Deployment Scenarios</name>

<section numbered="false" anchor="c1-minimal-deployment-zero-infrastructure"><name>C.1. Minimal Deployment (Zero Infrastructure)</name>

<t>Two organizations exchange pre-shared public keys via secure email.
Each agent signs Phase 1 mandates and Phase 2 records with its
Ed25519 key. No ledger, no external services. Suitable for
development and low-risk workflows.</t>

<t>Limitation: No non-equivocation (<xref target="equivocation"/>).</t>

</section>
<section numbered="false" anchor="c2-regulated-deployment-with-hash-chained-ledger"><name>C.2. Regulated Deployment with Hash-Chained Ledger</name>

<t>Phase 2 ACTs are submitted to a shared append-only ledger with
hash-chaining. Each recorded ACT extends a cryptographic chain,
providing tamper evidence for each ACT and the chain as a whole.
The ledger is shared between all regulated parties participating
in the workflow. Suitable for DORA compliance.</t>

</section>
<section numbered="false" anchor="c3-high-assurance-cross-organizational-deployment"><name>C.3. High-Assurance Cross-Organizational Deployment</name>

<t>Phase 2 ACTs are anchored to a SCITT Transparency Service. SCITT
receipts are attached to the audit record as non-equivocation proofs.
DID-based agent identities (Tier 3) enable self-sovereign key
management without shared CA infrastructure.</t>

</section>
<section numbered="false" anchor="c4-wimse-environment-integration"><name>C.4. WIMSE Environment Integration</name>

<t>In environments where WIMSE is already deployed, ACT-Mandate and
ACT-Record headers are carried alongside the WIMSE Workload-Identity
header. The ECT and ACT serve different purposes: the ECT records
workload-level execution in WIMSE terms; the ACT records the
authorization provenance and capability constraints that governed
the action.</t>

</section>
</section>
<section numbered="false" anchor="acknowledgments"><name>Acknowledgments</name>

<t>The author thanks the IETF WIMSE, OAuth, and SCITT working groups
for foundational work on workload identity, delegated authorization,
and transparent supply chain records that informs this specification.</t>

</section>


  </back>

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