This is the downloaded invoice review gate running in a disposable local n8n workspace. Everything on screen is synthetic.

The Manual Trigger starts the demo. Sample records emits two handoffs. The validation node checks the approval, customer reference, billing version, currency, line items, and arithmetic before anything could write downstream.

D-104 has matching amounts. It returns ready for review and a simulated review-queue payload. No queue or billing destination is connected.

D-105 is different. Its line items total seventeen hundred dollars against a seventeen-fifty approval. It returns needs review, shows the reason, and produces no draft.

For production, replace the sample with an approved source read, name the reviewer, persist destination IDs, and test uncertain write recovery with the target system.