EPI — Evidence for AI agents

Record. Seal. Verify offline. The answer is a file.

pip install epi-recorder
epi demo --no-browser    # record → seal → verify (no API key)

60-second path · With OpenAI · Integrations · CLI · Standards

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When someone asks what your agent did six months ago,
the answer should be a .epi file — not a dashboard login and a shrug.

epi-recorder captures agent decisions into a portable, signed, offline-verifiable artifact.
No phone-home required to open or verify.

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60-second path

Works without any LLM API key:

# demo.py
from epi_recorder import record, get_current_session

with record("demo.epi", goal="show the golden path"):
    s = get_current_session()
    s.log("tool.call", tool="lookup", id="A-1")
    s.log("tool.response", ok=True, balance=250)
    s.log("decision", action="approve", reason="within limit")

python demo.py
epi verify demo.epi
epi view demo.epi

Step	Command	What you get
Record + seal	python demo.py	Signed demo.epi (secrets redacted by default)
Verify	epi verify demo.epi	Integrity + signature checks offline
View	epi view demo.epi	Self-contained browser viewer (no server)

Typical first-run verify:

Check	Result
Integrity (SHA-256)	✅ Valid
Signature (Ed25519)	✅ Valid
Identity	⚠ UNKNOWN until you epi keys trust your key
Secrets	✅ Redacted by default (redact=True)

DECISION: WARN on first verify is normal — integrity and signature still pass.
Trust identity with: epi keys trust <name> after epi keys list.

That’s the product. Everything below is optional depth.

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With OpenAI

from openai import OpenAI
from epi_recorder import record, wrap_openai

client = wrap_openai(OpenAI())  # needs OPENAI_API_KEY

with record("agent.epi", goal="Answer a user question"):
    client.chat.completions.create(
        model="gpt-4o-mini",
        messages=[{"role": "user", "content": "Hello"}],
    )

python agent.py
epi verify agent.epi
epi view agent.epi

API keys in prompts/headers are redacted automatically before they land in the file.

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What a .epi file is

Every .epi uses the Envelope v2 container format — a polyglot HTML+ZIP binary that opens natively in any browser and can be extracted programmatically.

demo.epi
├── manifest.json     # Ed25519 signature + SHA-256 file hashes
├── steps.jsonl       # Timeline (hash-linked steps)
├── environment.json  # Runtime snapshot (sensitive env redacted)
├── viewer.html       # Offline forensic UI
└── VERIFY.txt        # Plain-text auditor instructions

Guarantee	How
Integrity	SHA-256 over every sealed member
Authenticity	Ed25519 signature on the manifest
Chain	Each step’s prev_hash links the timeline
Privacy	Default secret redaction (API keys, tokens, PII)

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Integrations

Stack	How
OpenAI	wrap_openai(OpenAI())
Anthropic	wrap_anthropic(Anthropic())
LangChain	EPICallbackHandler
LiteLLM	EPICallback
pytest	pytest --epi
Microsoft AGT	epi import agt <file>

# LangChain
from epi_recorder.integrations.langchain import EPICallbackHandler
llm = ChatOpenAI(model="gpt-4o-mini", callbacks=[EPICallbackHandler()])

# pytest — attach evidence to failing tests
pytest --epi

More: docs/FRAMEWORK-INTEGRATIONS-5-MINUTES.md

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CLI

Command	Purpose
epi verify <file.epi>	Offline integrity + signature check
epi view <file.epi>	Open offline viewer
epi run <script.py>	Run a script under recording
epi keys generate	Create a local signing key
epi keys list / trust / revoke	Key management
epi demo	Guided demo (alias of epi dev)
epi scitt register <file.epi>	Optional transparency anchor
epi import agt <path>	Import Microsoft AGT evidence

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Security defaults

• Redaction is on (redact=True). Keys/tokens/PII become ***REDACTED***:… placeholders.
• Prefer not using redact=False in production (it warns).
• Verification is local — no network required for integrity/signature.
• First-run identity WARN is expected until you trust your key.

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Standards & compliance

EPI produces evidence files that help with audit trails. It is not a compliance guarantee and does not provide legal advice. Whether evidence satisfies a specific regulatory threshold is for the auditor or notified body to determine.

Topic	Docs
EU AI Act Annex IV	docs/ANNEX-IV.md
AIUC-1 domains	docs/standards/aiuc-1-evidence.md
SCITT	docs/standards/scitt-predicate.md
CLI deep dive	docs/CLI.md
Auditors guide	docs/AUDITORS-GUIDE.md

epi verify agent.epi --aiuc1   # optional domain scoring

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Troubleshooting

Symptom	Fix
epi: command not found	Activate the same venv where you pip installed, or use python -m epi_cli
DECISION: WARN first verify	Normal — integrity/signature OK. Run epi keys trust … for KNOWN identity
Integrity: FAILED	File was modified after seal — re-record
Share / portal fails	Hosted features need a live backend; local record/verify never depends on them

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Project layout (contributors)

Path	Role
epi_recorder/	Python SDK (record, wrappers)
epi_core/	Container, crypto, redaction, verify
epi_cli/	epi command
website/	Public site source of truth (epilabs.org)
verify_portal/	Hosted verify/auth API (optional)
tests/test_core_loop_golden.py	Golden path regression

Website edits: only under website/, then python scripts/sync_website.py.

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License

MIT — see LICENSE.

Site: epilabs.org · Issues: GitHub Issues