A successful n8n execution proves that the nodes finished. It does not prove that the business outcome was correct.
The workflow can still:
write the same record twice;
accept a payload that changed shape;
make a decision from stale context;
A practical contract-and-receipt method for catching duplicate side effects, stale or malformed outcomes, and untrusted approval in green n8n executions.
A successful n8n execution proves that the nodes finished. It does not prove that the business outcome was correct.
The workflow can still:
write the same record twice;
accept a payload that changed shape;
make a decision from stale context;

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A source-to-target acceptance method for moving one legacy automation into n8n without copying silent failures.