The stack

Five layers. One evidence chain.

The reference architecture of AI governance engineering: five layers that turn governance from a stack of parallel documents into one system with a data path from policy to proof.

Layer flow

Follow one artefact from policy to proof.

Evidence flows up 05 Assurance & Continuous Compliance 04 Runtime Controls & Observability 03 Evals & Red Teaming as Evidence 02 Inventory & Transparency 01 Govern-as-Code

Layer 01 · Govern-as-Code

A policy verdict tied to a commit, a pull request or a deploy — machine-readable and reproducible.

Artefacts

  • Policy-as-code library under version control
  • Crosswalks that map each policy to the frameworks it serves
  • CI/CD wiring that runs the policy at the right gate
  • A structured policy verdict (allow/deny, rule id, input hash, timestamp) per evaluation

Maps to

  • EU AI Act Art. 9 (risk management)
  • ISO/IEC 42001
  • NIST AI RMF (Govern)
  • CSA AICM
  • OWASP Agentic ASI02/ASI03
Read layer 01 in chapter 04
Evidence flows up: each layer emits a structured artefact that layer 05 aggregates into audit-ready assurance.

How to read it

A build order, from policy to proof.

Read in chapter 04

The five layers

Policy, inventory, evals, runtime, assurance.

Govern-as-Code

Write the rule as code

Inherited
Question it answers
What is it allowed to do?
What it proves
A policy verdict tied to a commit, a pull request or a deploy — machine-readable and reproducible.
Artefacts
  • Policy-as-code library under version control
  • Crosswalks that map each policy to the frameworks it serves
  • CI/CD wiring that runs the policy at the right gate
  • A structured policy verdict (allow/deny, rule id, input hash, timestamp) per evaluation
Tool categories
  • Policy engines
    • OPA/Rego
    • Cedar
  • Machine-readable policy artefacts (proposed)
    • Policy Cards
Maps to
  • EU AI Act Art. 9 (risk management)
  • ISO/IEC 42001
  • NIST AI RMF (Govern)
  • CSA AICM
  • OWASP Agentic ASI02/ASI03
Read layer 01 in chapter 04

Inventory & Transparency

Inventory what is running

Inherited
Question it answers
What AI is running?
What it proves
A registry entry and its attached documents, ideally written by a deployment pipeline rather than typed by hand.
Artefacts
  • Agent registry: the runtime-aware inventory of every model, service and agent, each with an owner, a scope and a status
  • Transparency documents — model cards and data cards
  • AIBOM, the bill of materials for an AI system
  • FRIA and DPIA references linked to the registry entry
Tool categories
  • Registries and governance suites
    • ServiceNow
    • Credo AI
  • Agent-discovery tools
    • Zenity
  • AIBOM formats and generators
    • CycloneDX ML-BOM
    • SPDX 3.0 AI profile
    • OWASP AIBOM generator
Maps to
  • EU AI Act Art. 11 (technical documentation)
  • EU AI Act Art. 49/71 (registration and the EU database)
  • EU AI Act Art. 50 (transparency)
  • ISO/IEC 42001
  • NIST AI RMF (Map)
  • CSA AICM
  • OWASP Agentic ASI10
Read layer 02 in chapter 04

Evals & Red Teaming as Evidence

Run evals as evidence

New
Question it answers
What evidence proves it?
What it proves
A structured eval result — pass or fail against a threshold, versioned alongside the model it tested.
Artefacts
  • Eval suites and the eval gate that runs them
  • Capability and quality evals (groundedness, regression against a golden set)
  • Adversarial and red-team evals (jailbreaks, prompt injection, tool misuse)
  • Safety-threshold evals tied to a policy from layer 01
Tool categories
  • Evaluation frameworks
    • Inspect
    • promptfoo
    • DeepEval
  • Adversarial and vulnerability probes
    • Garak
    • Mindgard
    • Giskard
  • Retrieval-augmented quality
    • Ragas
Maps to
  • EU AI Act Art. 15 (accuracy, robustness, cybersecurity)
  • EU AI Act Art. 55 (GPAI systemic-risk evaluation)
  • ISO/IEC 42001
  • NIST AI RMF (Measure)
  • CSA AICM
  • OWASP Agentic ASI01/ASI02
Read layer 03 in chapter 04

Runtime Controls & Observability

Hold the line at runtime

New
What it proves
A stream of runtime decisions and traces.
Artefacts
  • Guardrails: input/output filters and tool-call mediation at the enforcement point
  • Observability: tracing and monitoring that turn agent behaviour into a control signal
  • Agent runtime identity: a workload identity, a bounded scope and a tested kill switch per actor
Tool categories
  • Guardrail frameworks
    • NVIDIA NeMo Guardrails
    • Meta LlamaFirewall
    • Lakera
  • Observability
    • Langfuse
    • Arize Phoenix
    • OpenTelemetry
  • Agent workload identity
    • SPIFFE/SPIRE
    • Microsoft Entra Agent ID
    • Okta Agent SSO
Maps to
  • EU AI Act Art. 14 (human oversight)
  • EU AI Act Art. 15 (robustness, cybersecurity)
  • EU AI Act Art. 12 (logging)
  • ISO/IEC 42001
  • NIST AI RMF (Manage)
  • CSA AICM
  • OWASP Agentic ASI02/ASI03/ASI10
Read layer 04 in chapter 04

Assurance & Continuous Compliance

Close with continuous assurance

Inherited
Question it answers
What evidence proves it?
What it proves
A live assurance store that any of the lower layers writes into and an auditor can read from.
Artefacts
  • Machine-readable evidence in a standard format (OSCAL)
  • Framework mappings generated from the evidence, not maintained beside it
  • Incident and reporting plumbing that meets obligations on the clock
Tool categories
  • Evidence format
    • OSCAL
  • GRC and AI-governance suites
    • Vanta
    • Drata
    • OneTrust
    • watsonx.governance
    • Holistic AI
    • Saidot
Maps to
  • EU AI Act Art. 17 (quality management)
  • EU AI Act Art. 72 (post-market monitoring)
  • EU AI Act Art. 73 (serious incident reporting)
  • ISO/IEC 42001, ISO/IEC 42005
  • NIST AI RMF (Govern, Manage)
  • CSA AICM
Read layer 05 in chapter 04

Inherited and new

Three layers inherited, two the AI forces.

Inherited from GRC engineering

Govern-as-Code (01), machine-readable evidence and Assurance & Continuous Compliance (05) come almost unchanged from GRC engineering — a specialisation of a method that already works.

New, forced by AI

Evals and red-teaming as controls (03) and agent identity and runtime control (04) are what AI forces the discipline to add: a model whose behaviour must be tested and an autonomous actor acting under delegated authority have no analogue in classic GRC.

Minimum viable stack

The spine, thinly, for a team of one.

A team of one cannot build all five layers at depth, but it can build the spine thinly, end to end — one vertical slice that touches every layer beats one layer built out and four left on paper.

Read in chapter 04

The tools

Categories are the substance; brands are illustrative.

Category Tool Layer
Policy engines OPA/Rego 01
Cedar
Machine-readable policy artefacts (proposed) Policy Cards 01
Registries and governance suites ServiceNow 02
Credo AI
Agent-discovery tools Zenity 02
AIBOM formats and generators CycloneDX ML-BOM 02
SPDX 3.0 AI profile
OWASP AIBOM generator
Evaluation frameworks Inspect 03
promptfoo
DeepEval
Adversarial and vulnerability probes Garak 03
Mindgard
Giskard
Retrieval-augmented quality Ragas 03
Guardrail frameworks NVIDIA NeMo Guardrails 04
Meta LlamaFirewall
Lakera
Observability Langfuse 04
Arize Phoenix
OpenTelemetry
Agent workload identity SPIFFE/SPIRE 04
Microsoft Entra Agent ID
Okta Agent SSO
Evidence format OSCAL 05
GRC and AI-governance suites Vanta 05
Drata
OneTrust
watsonx.governance
Holistic AI
Saidot

Read the stack in full.

The full reference architecture, layer by layer, with the mappings and the evidence.