Actenon Protocol

The neutral, open, implementation-independent boundary contract for proof-bound consequential execution. Defines the wire shape every Actenon artefact speaks. Zero runtime dependencies. Any language, any framework, any cloud.

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The Actenon ecosystem

The Protocol is one of five independent repositories that together close the execution gap — the gap between upstream authorization and the execution edge that actually performs a consequential side effect.

Repository	Role	Depends on	Packages
actenon-protocol ← you are here	The neutral wire contract — what every artefact looks like on the wire	—	actenon-protocol (PyPI) · @actenon/protocol-types (npm)
actenon-kernel	The open verifier — defines what a valid proof is	actenon-protocol	actenon-kernel (PyPI)
actenon-permit	The developer on-ramp and authority broker	actenon-kernel, actenon-protocol	actenon-permit (PyPI) · @actenon/sdk (npm)
actenon-scan	The independent static-analysis scanner	—	actenon-scan (PyPI)

Optional: actenon-cloud — a managed control plane (source-available; see its LICENSE). Not required by any component above; every capability in this ecosystem works without it.

The Protocol is the only repo the other four share as a common dependency — and even that is by choice, not by force. Every artefact defined here is implementable in any language with no runtime dependencies on any Actenon code.

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What this is

The Protocol defines the wire format that every Actenon component speaks. It is:

• Neutral — no runtime dependencies, no framework assumptions, no cloud requirement, no opinion on how you implement verification.
• Versioned — v1.1.0 (backward-compatible with v1.0.0). Versioning policy in VERSIONING.md.
• Cross-language — Python reference, TypeScript types, Go SDK, Rust SDK all conform to the same hash-locked conformance vectors.
• Hash-locked — conformance vectors are versioned and frozen; an implementation that passes v1.0.0 vectors will keep passing them forever.
• Implementation-independent — the same protocol can be implemented by Actenon, by a vendor, by an open-source competitor, or by an in-house team. Conformance, not pedigree, decides validity.

Why it exists

Modern agent stacks have plenty of proof formats, capability tokens, and audit schemas — JWT, PASETO, UCAN, macaroons, OAuth tokens, SPIFFE SVIDs, custom audit JSON. None of them, however, are designed to answer the question the execution edge needs to answer:

Is the exact consequential action about to execute still the exact action that was authorized — for this endpoint, this tenant, this subject, this target, this scope, this time window, and this single execution attempt?

The Protocol exists to give that question a public, implementation-independent answer. It defines:

• the request shape (Action Intent)
• the proof shape (ExecutionProof, a.k.a. PCCB — Proof of Constrained Capability Bound)
• the success shape (ExecutionReceipt)
• the failure shape (ExecutionRefusal)
• the discriminated result shape (ExecutionResult)
• the boundary-mapping shape (BoundaryManifest)

…and nothing else. It does not define how proof is issued, how policy is evaluated, how credentials are brokered, or how tenants are managed. Those are intentionally left to the implementer.

The five artefacts

Artefact	Purpose	Schema
ExecutionProof (PCCB)	Cryptographic proof that a specific action was authorized for a specific audience, tenant, subject, target, scope, and time window. Single-use.	schemas/execution_proof.v1.json
ExecutionReceipt	Durable record that a proof was verified and an action executed (or definitively refused before execution, in the refused-receipt path).	schemas/execution_receipt.v1.json
ExecutionRefusal	Structured refusal with two-layer disclosure (public-safe disclosed_code + trusted-only internal_code).	schemas/execution_refusal.v1.json
ExecutionResult	Discriminated union: BrokeredExecutionResult | ResourceOwnedExecutionResult — disjoint field sets, no ambiguity.	schemas/execution_result.v1.json
BoundaryManifest	Declarative mapping from HTTP endpoints to canonical Actenon actions, with parameter extraction rules.	schemas/boundary_manifest.v1.json

The two execution modes

Mode	Who verifies	Who executes	Receipt issuer	When to use
brokered	In-stack Kernel verifier (typically inside the agent framework)	Broker (Permit) — credentials resolved server-side after verification	Broker	You control the agent framework and want credentials never to reach the agent
resource_owned	Resource boundary (independent Kernel verifier)	The resource itself (FastAPI route, Express endpoint, Go handler)	Resource	You cannot fully trust the agent, or the resource is shared by multiple callers, or the resource team is a separate org

Submission is not execution. A submitted state is non-final. succeeded requires a cryptographically verified receipt. The protocol enforces this distinction with disjoint result field sets — brokered and resource-owned results cannot be confused.

The mode is explicit, never inferred — it appears on every proof, receipt, refusal, and result. There is no "default mode."

Canonicalisation profile — ACTENON-JCS-STRICT-1

Every signed and digested artefact in the protocol uses the same canonicalisation profile:

canonicalization_profile: "actenon-jcs-sha256-v1"   # cross-repo wire contract name
canonicalization_label:  "ACTENON-JCS-STRICT-1"      # protocol-canonical label

This is a strict subset of RFC 8785 (JCS). It freezes:

• deterministic JSON canonicalisation (sorted keys, no insignificant whitespace)
• SHA-256 digesting
• float rejection — floating-point values are refused outright (model monetary/quantity values as integers or strings)
• Unicode and string handling
• duplicate JSON object keys are invalid — runtime parsers must reject duplicates before canonicalisation
• base64url without padding where base64url is required
• 1 MiB max output, 32-level depth limit
• no in-place future changes

See canonicalisation/ACTENON-JCS-STRICT-1.md. This profile is what makes action-hashes stable across Python, TypeScript, Go, and Rust implementations.

Refusal taxonomy — two-layer disclosure

20 canonical refusal codes organised in a two-layer model:

• disclosed_code — public-safe umbrella code returned to untrusted callers. Always collapses to one of a small set (PROOF_INVALID, REPLAY_DETECTED, UNAUTHORIZED, FORBIDDEN, ACTION_REFUSED).
• internal_code — specific code disclosed only to trusted callers (AUDIENCE_MISMATCH, ACTION_MISMATCH, TENANT_MISMATCH, SUBJECT_MISMATCH, EXPIRED, NOT_YET_VALID, REVOKED, SCOPE_EXCEEDED, BUDGET_EXCEEDED, RATE_LIMITED, APPROVAL_REQUIRED, PARAMETER_DIGEST_MISMATCH, etc.)

This prevents an attacker from probing the verifier by enumerating refusal codes, while still giving operators the specific information they need to debug. Full catalogue in refusals/catalogue.v1.yaml.

Identifier prefixes

The protocol reserves a small set of identifier prefixes so any artefact is recognisable across implementations:

Prefix	Artefact
intent_	Action Intent
authz_	Authorised Execution Intent
grant_	Grant (capability token)
proof_	ExecutionProof / PCCB
exec_	Execution attempt
rcpt_	ExecutionReceipt
rful_	ExecutionRefusal

See identifiers/prefixes.v1.yaml.

Multi-language SDKs & conformant implementations

Implementation	Status	Path
Python reference	Stable v1.1.0 on PyPI	python/ — pip install actenon-protocol
TypeScript types	Stable v1.0.0 on npm	typescript/ — npm install @actenon/protocol-types
Go SDK	Conformant	in actenon-kernel sdk/go/
Rust SDK	Conformant	in actenon-kernel sdk/rust/
OpenAPI 3.1 components	Stable	openapi/components.yaml — drop into any OpenAPI-aware toolchain
JSON Schemas	Stable v1	schemas/ — validate any artefact in any language

Every implementation runs against the same hash-locked conformance vectors in conformance/vectors/. Conformance, not pedigree, decides validity.

Install

pip install actenon-protocol
npm install @actenon/protocol-types

Optional extras

The runtime package has zero dependencies — only the Python standard library. Pydantic types, YAML loading, and conformance tooling are gated behind optional extras so adopters who only need the wire contract pay no dependency cost:

pip install "actenon-protocol[types]"        # Pydantic models for the protocol shapes
pip install "actenon-protocol[yaml]"         # Direct YAML loading of the refusal catalogue
pip install "actenon-protocol[conformance]"  # jsonschema + rfc8785 for the conformance runner
pip install "actenon-protocol[all]"          # all of the above

Use

from actenon_protocol import (
    ExecutionMode,                 # "brokered" | "resource_owned"
    BrokeredExecutionState,        # succeeded | failed | refused | outcome_unknown
    ResourceOwnedExecutionState,   # submitted | accepted | refused | ...
    canonicalize_json,             # ACTENON-JCS-STRICT-1 canonicalisation
    RefusalCode,                   # 20+ structured refusal codes
    ExecutionProof,
    ExecutionReceipt,
    ExecutionRefusal,
    BoundaryManifest,
)

# Canonicalise any artefact deterministically (raises on floats / duplicate keys)
canonical_bytes = canonicalize_json({
    "action": "payment.refund",
    "target": "invoice:INV-7831",
    "amount_minor": 250000,   # integer minor units — never floats
    "currency": "USD",
})

Conformance vectors

The protocol ships 129 hash-locked test vectors across 6 categories:

Category	Valid	Invalid	Total	What it tests
canonicalisation	22	15	37	ACTENON-JCS-STRICT-1 (float rejection, duplicate keys, Unicode, depth/size limits)
proof	15	14	29	ExecutionProof schema, identifier prefixes, protocol version, required fields
receipt	12	8	20	ExecutionReceipt schema, outcome enum, both execution modes, required fields
refusal	20	5	25	All 20 refusal codes from the catalogue, two-layer disclosure, retryability
execution-mode	10	0	10	Mode distinction (brokered vs resource_owned), mode-specific constraints
execution-result	4	4	8	Discriminated union: disjoint field sets
Total	83	46	129

129 vectors run on every PR via the CI workflow, across Python 3.10 / 3.11 / 3.12, plus the TypeScript conformance suite (21 tests).

External implementations — earn "Actenon-compatible v1.1.0"

An external implementation is Actenon-compatible v1.1.0 if it accepts every valid vector and rejects every invalid vector. The Runner Specification defines the interface, and the standalone runner is a ready-to-use Python script that external implementations can subclass:

pip install -e ".[dev]"

# Run the conformance suite against the Python reference
python conformance/runner.py

# JSON output for CI integration
python conformance/runner.py --json

# Run a single category
python conformance/runner.py --category refusal

Vectors are generated by conformance/generate_vectors.py for maintainability — regenerate with python conformance/generate_vectors.py. See conformance/README.md for details.

Key guarantees

1. Mode is explicit, never inferred — on every proof, receipt, refusal, and result.
2. Canonicalisation is deterministic — ACTENON-JCS-STRICT-1 (RFC 8785 subset), sorted keys, no whitespace, floats rejected, duplicate keys rejected.
3. Refusal codes have two layers — public-safe umbrella (PROOF_INVALID) + trusted detail (AUDIENCE_MISMATCH).
4. Results are discriminated — brokered and resource-owned results have disjoint field sets.
5. Backward-compatible — v1.1.0 is purely additive over v1.0.0.
6. Hash-locked — conformance vectors are versioned and frozen.
7. No ambient authority — no field implies trust in an issuer, signer, or control plane. Trust is configured by the verifier.

What's in this repo

protocol/            # Human-readable specs (01–12)
  01-action-intent.md
  02-execution-proof.md
  03-execution-modes.md
  04-execution-receipt.md
  05-execution-refusal.md
  06-boundary-manifest.md
  07-canonicalisation.md
  08-outcome-codes.md
  ...
schemas/             # JSON Schemas (v1) — validate any artefact in any language
canonicalisation/    # ACTENON-JCS-STRICT-1 profile definition + test fixtures
identifiers/         # Identifier prefix registry (prefixes.v1.yaml)
refusals/            # Refusal-code catalogue (catalogue.v1.yaml)
conformance/         # Hash-locked conformance vectors + Python suite
python/              # Python reference implementation (pydantic models)
typescript/          # TypeScript types (@actenon/protocol-types)
openapi/             # OpenAPI 3.1 components

Integration guide

For the full adoption path — including how to wire the protocol into an existing service without pulling in any other Actenon repo — see INTEGRATION_GUIDE.md. The short version: install this package, validate every incoming Action Intent + ExecutionProof against the JSON Schemas, canonicalise with canonicalize_json, and verify the proof signature against your configured issuer keys. That alone gives you protocol-conformant refusal — even before you adopt the Kernel, Permit, or Cloud.

What the Protocol does NOT do

• Issue grants or proofs (that's Permit's job, or any compliant issuer's job).
• Verify proofs (that's the Kernel's job, or any compliant verifier's job).
• Execute provider calls (that's the broker/adapter's job).
• Manage tenants, approvals, evidence, or audit (that's Cloud's job, or your own).
• Make any trust claim about the issuer, signer, or control plane.
• Provide a hosted transparency log (the artefact shape exists; the operation is separate).

The Protocol is the contract. It is deliberately the smallest, most boring, most implementable thing in the ecosystem — because that is exactly what a wire contract needs to be.

Independence

This repo depends on nothing. Zero runtime dependencies. It can be adopted by any implementation in any language without pulling in Permit, Kernel, Cloud, or Scan. Conformance is the only claim an implementation needs to make.

License

Apache-2.0 — see LICENSE.