A retry should
not send twice.

See a repeated signup produce duplicate messages, then run the repaired workflow against the same failure. Source, tests and recorded results are included.

Download source and tests ↗

Python 3.10+ · standard library only · no API keys or network connection needed.

EXECUTABLE EVIDENCE

Eight failure
and recovery cases.

These are recorded results from the downloadable Python program, using separate local databases for workflow state and the simulated provider. The page does not contact an email provider.

Loading recorded results…

Download raw result JSON

REPRODUCE IT

Run the proof.

Extract the download into an empty directory, then run:

python3 webhook_proof.py
python3 -m unittest -v test_operation_guard test_webhook_proof

What is tested

Duplicate delivery, a lost response after acceptance, restart after contact creation, missing consent, an existing unsubscribe, conflicting event input, a crash before sending, and concurrent form events. One test terminates a real child process after the simulated provider commits a message.

What remains provider-specific

This is not a WordPress plugin, Make scenario or Brevo connector. A customer repair needs the actual failing path, provider capabilities, consent evidence and agreed access. Authentication, provider reconciliation and production data handling must be implemented for that environment.

One bounded paid repair

CooperLux performs the engineering with approved AI tools. Reply to the proposal accompanying this proof with the failing step and desired result. Scope, price, access and acceptance are agreed before customer work begins. No payment is collected by this demonstration.