crewai-aer1

AER-1 verifiable execution receipts for CrewAI crews. One checkable receipt per tool call, emitted through CrewAI's own typed event bus. No changes to your Crew, Agent, or Task definitions.

For whole-run workflow receipts with a Merkle root (AER-1 Section 8), see aer1-crewai.

Quickstart

from crewai import Agent, Crew, Task
from crewai_aer1 import AER1Listener

receipts = AER1Listener()  # keep this reference alive for the process

researcher = Agent(
    role="Researcher",
    goal="Find verifiable facts",
    backstory="A careful analyst.",
    tools=[my_search_tool],
)
task = Task(description="...", expected_output="...", agent=researcher)
crew = Crew(agents=[researcher], tasks=[task])

crew.kickoff()
receipts.save("receipts.jsonl")
print(f"{len(receipts.receipts)} verifiable receipts recorded")

That is the whole integration. The listener subclasses CrewAI's BaseEventListener and registers handlers for ToolUsageFinishedEvent (and CrewKickoffStartedEvent for crew context) on the singleton event bus in setup_listeners. Because the bus is process-wide, every crew you kick off is covered with zero code intrusion. Just make sure the module that instantiates AER1Listener is imported, and the instance stays alive (not garbage collected), or handlers stop firing.

What a receipt proves

Each receipt follows the AER-1 receipt record (IETF Internet-Draft draft-zambo-aer1, Sections 3-6): a stable id, RFC 3339 timestamp, tool identity, provenance class (EXECUTED BY CREWAI), base64 canonical bytes, and a SHA-256 output commitment anyone can recompute. A receipt proves the recorded bytes were not changed after the tool ran. It does not prove the tool was correct.

Honest boundaries, enforced in code:

• Cached tool results (from_cache=True) are skipped. Nothing executed, so there is nothing to attest.
• Tool calls the tool itself reported as failed are skipped. There is no successful result to commit to.
• A listener exception never breaks a crew run. Every handler is guarded.

Verify a receipt yourself

from crewai_aer1 import verify_receipt
ok, reason = verify_receipt(receipts.receipts[0])

Spec and conformance

• Spec: https://datatracker.ietf.org/doc/draft-zambo-aer1/ (open Internet-Draft)
• Conformance kit: https://gitlab.com/rambozambodotdev/zambo

License

MIT