From AI conversation to verified payment and invoice

Collect the exact products, quantity, delivery destination, taxes, currency, customer identity, and approved discount. Read current price and availability from business systems, not conversation memory.

Show the customer a concise confirmation before checkout. If terms are ambiguous or a concession exceeds policy, route to a human.

Calculate line items, taxes, shipping, expiry, and totals on the backend. Store an immutable price snapshot and quote version, then link it to the customer, tenant, conversation, and responsible service.

The AI can explain the quote but cannot change its amount in free text. Revisions create a new version so the audit trail remains understandable.

Create the provider session server-side with quote ID, tenant ID, and an idempotency key in trusted metadata. Return only the hosted payment URL to the channel.

Never accept an amount, success flag, or invoice status from return-page query parameters. The page may show pending while the signed webhook is processed.

Verify the raw request signature using the provider webhook secret. Check account ownership, currency, amount, quote reference, and event status before marking the quote paid.

Store the event ID and process it idempotently. Out-of-order or repeated events must converge on the correct state without multiple receipts.

Generate an invoice with legal identity, tax fields, customer details, numbered line items, paid amount, currency, payment reference, and issue date. Store an immutable copy and attach it to the quote and conversation.

Send through approved email and conversation channels. Track delivery separately from payment so a failed email can be retried without changing the financial record.

Exercise abandoned checkout, failed payment, delayed and duplicate webhooks, mismatched amount, refund, expired quote, unavailable email, and a customer reopening the link.

Dashboards should distinguish payment conversion from technical delivery. Support needs a safe resend action, while finance needs reconciliation and complete history.