complete codex docs

docs/modules/billing.md

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+# Billing
+
+## Purpose
+
+Commercial billing, provisioning, invoices, orders, transactions, coupons, and payment gateway integration.
+
+## Current Status
+
+- Functional
+- Partial / complex
+
+## Dependencies
+
+- Payment gateways
+- provisioning flow
+- server lifecycle and expiration logic
+- docs under `Panel/modules/billing/docs/`
+
+## Database Tables
+
+- `billing_services`
+- `billing_orders`
+- `billing_invoices`
+- `billing_transactions`
+- `billing_coupons`
+- `billing_config`
+- `billing_paypal_webhook_events`
+- `billing_paypal_errors`
+
+## Agent Interaction
+
+- indirect through provisioning and server lifecycle
+
+## User Workflow
+
+- shop/service purchase
+- invoice/payment flow
+- renewals
+- account/service status
+
+## Admin Workflow
+
+- configure payment gateways
+- manage coupons and pricing
+- inspect invoices/transactions
+- manage provisioning behavior
+
+## Security Concerns
+
+- payment keys and webhook secrets
+- user identity and billing data
+- service suspension/expiration behavior
+
+## Known Issues
+
+- large and complex module surface
+- requires strong testing around provisioning lifecycle
+
+## Missing Functionality
+
+- cleaner linkage from billing events to server state
+- clearer expiration/suspension docs and UX
+
+## Suggested Future Improvements
+
+- simplify provisioning audit
+- add clearer service lifecycle feedback
+- link billing more directly to support and server monitor
+
+## Recommendation
+
+- Keep / Rewrite
+