Can I vibe code PayTrace?

1. System Architecture: Build a Next.js payment middleware application that wraps existing Stripe API calls to capture and append Level 2 and Level 3 credit card data for B2B transactions. The goal is to optimize interchange fees using existing compliant rails rather than building a PCI-scoped gateway from scratch. Use Stripe Elements for card input to keep PCI scope at SAQ A.

2. Data Model:
- Merchant Account: Store API credentials, merchant tax ID, default ship-from zip code, and currency settings.
- Invoice: Record line items, product codes, commodity codes, unit prices, tax amounts, shipping fees, and customer PO number.
- Transaction Log: Store authorization status, payment intent IDs, interchange qualification state (L1, L2, L3), and processor response tokens.

3. Core Functionality & Level 2/3 Payload Logic:
- Construct an API endpoint that receives invoice details before payment execution.
- Automatically validate and format Level 2 fields (Tax Amount, Shipping Amount, Tax Exempt Flag, Customer PO Number).
- Automatically validate and format Level 3 line-item fields (Item Description, Product Code, Commodity Code, Quantity, Unit Cost, Discount Amount, Item Tax Amount).
- Pass these parameters into the Stripe `payment_intent.create` payload using the `level3` data block.
- Handle fallbacks: If required Level 3 line-item attributes are missing, default to a formatted Level 2 request to prevent transaction rejection.

4. Failure Modes & Edge Cases:
- Math Discrepancy: Ensure the sum of individual line item amounts + tax + shipping strictly equals the PaymentIntent grand total, or log a payload validation error prior to API submission.
- PCI Compliance: Ensure raw credit card numbers (PANs) never touch your server code or database; rely entirely on tokenized Stripe objects.
- Network Errors: Gracefully catch API timeouts and retry transaction requests with idempotency keys.

5. Out of Scope: Direct socket connections to VisaNet/Mastercard, ISO 8583 packet construction, credit card vaulting, host-based hardware security modules (HSMs), or acquiring bank merchant underwriting.

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