Billing & Invoicing Lifecycle

IMPLEMENTED

Sheba ISP ERP automates recurring monthly subscription invoicing for thousands of subscribers while ensuring strict accounting isolation.

1. End-to-End Financial Lifecycle

The financial architecture guarantees atomic propagation across all stages:

Invoice -> Invoice Lines -> Payment -> Payment Allocation -> Ledger -> Customer Balance -> Billing Status -> Network Sync

2. Invoicing & Discount Rules

1. Idempotent Billing: A customer cannot receive more than one recurring subscription invoice for the same billing_month.
2. Itemized Line Computation: For each InvoiceLine, the net charge is computed as: line_total = (quantity * unit_price) - discount + tax_amount
3. Discount Precedence: An explicit discount passed in the invoice creation payload (including 0.00) is strictly preserved. If omitted, the default customer.discount is applied.
4. Advance Auto-Settlement: If a customer has an existing positive advance balance (customer.advance_amount > 0), the billing engine immediately executes apply_advance_to_invoice(), deducting advance funds to settle the new bill and creating an audited PaymentAllocation.
5. Proration: Mid-cycle activations calculate prorated fees based on remaining days in the billing month.

3. Recharges & Non-Destructive Reversals

• Recharge Activation: Recharges extend customer validity, clear outstanding invoices, post credit ledger entries, and schedule post-commit router sync jobs (ENABLE_USER).
• Compensating Reversal: Because financial records are immutable, reversing a recharge does not delete database rows. It appends a compensating REVERSAL ledger entry, marks the payment as refunded, rolls back the expiration date, re-opens affected invoices, and adjusts surplus advances.