# OTB Billing Design Notes

## Current Version
0.0.2

## Purpose
OTB Billing is the billing and payment tracking component for OutsideTheBox.

It is intended to:
- track clients
- track services
- issue invoices
- record payments
- support bookkeeping visibility
- integrate with outsidethedb while keeping billing records logically separate

## Supported payment directions
- Square
- Interac e-Transfer
- Crypto

## Multi-currency design
The schema supports multi-currency from day one.

Current intended currencies:
- CAD
- ETHO
- EGAZ
- ALT

### Rule
Store both:
- actual payment currency and amount
- CAD-equivalent snapshot when relevant

Example:
- payment_currency = EGAZ
- payment_amount = 12.50000000
- cad_value_at_payment = 47.82

This keeps both crypto-native records and bookkeeping-friendly reporting.

## Core tables
- clients
- services
- invoices
- invoice_items
- payments
- audit_log

## Relationship flow
client -> service -> invoice -> invoice_items -> payment

## Notes
- services are linked to clients
- invoices are linked to clients and optionally to services
- invoice items can optionally reference services
- payments reference both invoice and client
- audit_log provides change history for future accountability and troubleshooting

## Planned future additions
- recurring invoice generation
- reminders / overdue handling
- dashboard counts
- service suspension workflow
- integration hooks to outsidethedb
- client verification records