The standard guardrails stack
Most modern AI guardrails architectures follow a similar 5-layer structure:
- Input Screening — prompt filtering, injection detection
- Dialog Control — flow control, policy enforcement
- LLM Generation — model output
- Output Validation — structure, safety, correctness
- Audit Layer — logging, traceability, compliance
Layers 1–4 are well-defined and actively implemented across frameworks.
Layer 5 is where things break down.
The problem with Layer 5
Almost every architecture mentions audit logging as a requirement:
“log everything for compliance”
“ensure traceability”
“support forensic reconstruction”
But in practice, this usually means logs.
Logs are not designed for compliance-grade evidence:
- not portable
- not verifiable
- not tamper-evident
- difficult to share across systems
They are implementation details, not artifacts.
Why this matters
Regulations like the EU AI Act (Article 12) require:
- traceability
- auditability
- documentation of system behavior
This is not satisfied by raw logs sitting inside an application.
Auditors, regulators, and external systems need portable evidence, not internal debug data.
The missing piece: portable evidence
What’s missing is a standardized artifact layer that sits on top of guardrails systems.
Instead of:
→ “we logged what happened”
We need:
→ “here is a verifiable record of what happened”
EPI as Layer 5
EPI Recorder is an open-source approach to this problem.
It produces .epi artifacts — portable, signed records of:
- what input was processed
- what policies were applied
- what was allowed, blocked, or modified
- what validations passed or failed
GitHub: https://github.com/mohdibrahimaiml/epi-recorder
PyPI: https://pypi.org/project/epi-recorder/
These artifacts can be:
- stored
- shared
- independently verified
- used in compliance workflows
How this fits into existing systems
This does not replace guardrails frameworks.
It complements them.
Any system (NeMo Guardrails, Guardrails AI, Agent Control, etc.) can add:
- a post-execution hook
- an export API
- or a plugin
to produce portable evidence artifacts.
Rethinking Layer 5
The industry already agrees Layer 5 is required.
The mistake is treating it as “logging.”
Layer 5 should be:
→ a portable evidence layer
→ standardized artifacts
→ verifiable outputs
Not just logs.
Final thought
Guardrails control behavior.
Evidence proves it.
Without portable evidence, compliance remains incomplete.
Layer 5 is not logging.
Layer 5 is evidence.
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