Set Up Invoice-Specific PayNow QR Payments for Xero

A receiving proxy must not be inferred from a business UEN alone. The implementation starts by decoding the official QR issued by the bank or payment provider and treating its proxy type, proxy value, merchant metadata, and payment settings as authoritative.

The original QR remains preserved byte-for-byte as a private fallback asset. Live payment addresses, customer information, credentials, domains, and provider-issued assets should not enter a public repository without explicit approval.

The dynamic QR should retain the provider-issued merchant profile while setting the point-of-initiation method, fixed invoice amount, invoice number reference, editable-amount indicator where required, and a recalculated CRC-16/CCITT-FALSE checksum.

Currency, amount, reference, and merchant configuration are validated before rendering. Public URL parameters must not be allowed to replace the merchant proxy or intended recipient.

The page should include a provider-approved fallback with the complete payment address and the provider's instructions. It should use plain PayNow text unless an authorised brand asset is supplied.

Automated tests should cover the decoded merchant profile, proxy type, amount, reference, checksum, and preservation hash of the source QR so later changes do not silently alter the receiving identity.

Netlify and VPS deployment are alternative routes. Either route should use a reversible release, verify the build and tests, confirm HTTPS and service health, and retain a rollback path.

A controlled low-value scan in a Singapore banking app is required before rollout. The app must resolve the expected recipient and show the intended amount and invoice reference.

Rendering a QR does not prove that money was received. Bank evidence and accounting reconciliation remain the source of truth, and the page must not claim payment success.

The proposed Xero custom payment URL should be shown for review before configuration changes. Creating payments, altering invoices, or changing branding-theme payment services requires explicit approval for the exact action. The living Gist contains the complete agent prompt and prerequisite controls.