01
Lost acknowledgement
The write succeeds, but the acknowledgement never reaches the agent.
lost_acknowledgementReliability testing for AI agents
Agents retry.
Side effects do not rewind.
AgentIdem tests state-changing AI agents under retries, duplicate delivery, interrupted execution, and lost acknowledgements before those failures reach production.
trace / refund-agent
unsafeTimeKindOperationStatus
00:00.182READget_paymentRECEIVED
00:00.421WRITErefundSUCCESS
00:00.422ACKrefundLOST
00:01.086WRITErefundSUCCESS
Duplicate successful write
refund · identity payment_482
The failure mode
The action succeeded. The agent thinks it failed.
Distributed systems can lose acknowledgements after external state has already changed. A retry can then repeat the same logical write.
01Agent decides to issue a refund
02The external refund succeeds
03The acknowledgement is lost
04The agent observes a failure
05Retry logic executes the refund again
Fault scenarios
Test the failures retry logic usually hides.
02
Before-operation failure
Execution fails before the selected state-changing operation occurs.
before_operation_failure03
Duplicate delivery
The same agent invocation runs more than once, simulating redelivery or retry.
duplicate_deliveryStart testing