Build an approval-first invoice extraction workflow

Document extraction should produce a reviewable proposal. It should not turn a plausible total into an accounting entry without validation and authenticated approval.

Bind approval to exact content

The automation lab hashes a synthetic proposal.

from automation_cases import invoice_approval_case

result = invoice_approval_case()
assert result["original_authorized"] is True
assert result["changed_authorized"] is False
assert result["proposal"]["total"] == 1180.0
assert result["accounting_write"] is False

Changing 1,180 to 11,800 invalidates approval. No invoice parser or accounting system ran.

Build staged controls

Ingest an immutable source with file digest, origin and duplicate key. Extract typed fields with page/region references. Validate vendor identity, currency, arithmetic, date, purchase-order rules and required fields. Route failed checks to review rather than filling gaps.

The approval view should show source evidence, proposed fields, validation results and downstream action. Authenticate the reviewer, record role, time, decision and proposal digest. A later change requires a new decision. Execute the write with an idempotency key and reconcile the returned record ID.

Keep rejected, expired and unavailable-review paths explicit. Minimize invoice data in logs and restrict source storage. Measure field errors, review corrections, cycle time and duplicates before claiming value.

The Generative & Agentic AI course combines multimodal extraction with approval and idempotency.

Exercise

Use three synthetic invoices: valid, duplicate and arithmetic mismatch. Prove only the exact approved proposal reaches a stubbed write and replay creates no duplicate.

Continue learning

This article is part of the Business automation with AI sequence. Use the neighbouring tasks when you need the prerequisite or the next application.

• Review the prerequisite or neighbouring task in Design an automation brief before choosing n8n or an agent.
• Continue with Automate support categorization with a fallback queue.

Reference: Zapier Human in the Loop statuses.