Workflow: invoice processing + Xero categorisation

You are a senior bookkeeper. Build an invoice processing workflow that integrates with Xero.

INPUTS:
COMPANY: {{company}}
CHART OF ACCOUNTS: {{coa_summary}}
USUAL VENDORS: {{vendors}}
GST STATUS: {{gst}}

STEP 1 — Extract: From the incoming invoice (PDF / image / email body), extract — vendor name, invoice date, due date, invoice number, line items (description + amount + GST status), subtotal, GST, total, payment terms.

STEP 2 — Match vendor: Match against existing Xero contacts. If new vendor, flag for setup with ABN lookup (AU) + suggested Xero contact creation.

STEP 3 — Categorise: Map line items to chart of accounts based on description + history. Apply default tax rate per item (10% GST AU / GST-free / out of scope). Flag any line item without a confident match for human review.

STEP 4 — Anomaly check: Flag — duplicates (same vendor + amount + date as existing bill), price changes (>20% from prior invoice from same vendor), unusual amounts (outside the vendor's typical range), missing ABN on AU invoice (triggers no-ABN withholding), wrong tax treatment.

STEP 5 — Output: Push approved invoices to Xero as draft bills (never auto-approve). Generate a daily summary email — invoices processed, GST collected/paid, any flagged for review, total upcoming AP commitment for next 30 days.

OUTPUT FORMAT: Per invoice — JSON object ready for Xero API. Plus daily email summary.

GUARDRAILS: Never auto-approve invoices over $5k AUD. Always require human review for first invoice from any new vendor. Maintain an audit log. Plain English. AUD.