Catch valid-looking n8n values mapped from the wrong source with collision fixtures, source-path assertions, and provenance receipts.
A workflow can finish successfully, pass a JSON schema, and still update the wrong customer.
The value is present. The type is correct. The meaning is wrong because it came from the wrong source path.
The failure that a schema cannot see
Imagine an order webhook with two valid identifiers:
{
A practical contract-and-receipt method for catching duplicate side effects, stale or malformed outcomes, and untrusted approval…
Your n8n workflow ran successfully. The logs say 200. Your monitoring dashboard is green. But three...
It's 11 PM. Your monitoring pings. The n8n workflow that processes customer orders is red. You open...
Every n8n workflow I audit has at least three of these mistakes. They all share the same trait: they...
Pydantic and JSON-schema guarantee the shape of a tool call. They say nothing about whether it was...
A source-to-target acceptance method for moving one legacy automation into n8n without copying silent failures.
