Your n8n Workflow Passed Schema Validation—and Updated the Wrong Customer

Short summary

An n8n workflow can pass JSON schema validation yet update the wrong customer because type-correct values can come from the wrong source path. The article demonstrates semantic mapping failures where actor IDs get selected instead of customer IDs, and provides concrete fixtures, code-level checks, and receipt patterns to catch these errors before irreversible actions. It advocates testing with deliberately different candidate values, verifying item relationships, and maintaining terminal receipts for audit and idempotency.

• •Schema validation confirms type correctness, not semantic correctness of data source selection
• •Use deliberately different candidate values in fixtures to catch wrong-authority mappings
• •Place semantic checks before irreversible nodes and store non-sensitive receipts for audit and replay safety

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