crewai-zambo

Verifiable AER-1 execution receipts for CrewAI agents. Publish CrewAI task events as public, verifiable receipts at zambo.dev.

Receipts follow AER-1, the IETF draft for verifiable execution receipts created by Brennan Zambo.

Install

pip install crewai-zambo

Ten-line example

from crewai_zambo import ZamboCrewListener

listener = ZamboCrewListener()
result = listener.on_task_completed("Summarize this task", "completed")
print(listener.last_receipt_url or result)

Attach ZamboCrewListener to the CrewAI listener mechanism supported by your installed CrewAI version, or call on_task_completed from a task completion hook. The listener prints each public https://zambo.dev/run/{id} URL and keeps the most recent URL in last_receipt_url.

The receipt describes what the live endpoint recorded and observed. It does not prove an outside outcome that the endpoint did not observe. Set ZAMBO_API_URL when using a compatible Zambo host. Listener failures are available in receipt_errors.

Local AER-1 receipts (no network needed)

The package also mints AER-1 execution receipts locally, with no API calls. Pass emit_aer1=True to record every event as a verifiable receipt on your own machine:

from crewai_zambo import ZamboCrewListener

listener = ZamboCrewListener(emit_aer1=True)
listener.on_task_completed("Summarize this task", "completed")

receipt = listener.last_local_receipt
print(receipt["id"], receipt["output_hash"])

Or mint receipts directly for any tool call:

from crewai_zambo import mint_receipt, verify_receipt

receipt = mint_receipt("my_tool", {"query": "hello"}, {"answer": "hi"}, ms=42)
assert verify_receipt(receipt)  # recomputes the SHA-256 locally

Local receipts follow the AER-1 core members (id, created_at, tool, provenance_class, canonical_bytes, output_hash) and use the provenance class EXECUTED BY CREWAI-ZAMBO, naming this package as the recording system. They pass the same hash-recomputation check as any AER-1 receipt.

Project homepage: https://zambo.dev AER-1 receipt spec: https://zambo.dev/aer-1/

Guides

• Execution Receipts for AI Agent Frameworks
• What Is an AI Agent Execution Receipt?