| name | billing-stripe |
| description | Work with Stripe billing — subscriptions, plans/prices, the Customer Portal, credits, usage metering, invoices, and webhook events. Use when changing plans, handling a new Stripe webhook, debugging a payment/subscription flow, or touching credit balances and usage. |
Billing & Credits (Stripe)
Billing is a thick service at backend/app/services/billing/. Routes never touch Stripe directly — everything goes through BillingService (the facade in facade.py, re-exported from __init__.py).
Layout
| File | Responsibility |
|---|
facade.py | BillingService — the only thing routes/workers import |
checkout_service.py | Checkout sessions (seat-configurable) |
subscription_service.py | Subscription CRUD, change plan, cancel/reactivate |
credit_service.py | Credit ledger + usage aggregation |
stripe_client.py | Thin Stripe API wrapper |
webhook_handler.py + handlers/ | Event processing (customer / invoice / payment / subscription) |
pricing.py | Static plan/price data |
exceptions.py | Billing domain errors (extend core/exceptions) |
Data model: plan / price mirror Stripe products; subscription is one-per-org; stripe_event is an idempotency log; credit_transaction is an immutable ledger; usage_event records per-message token spend, rolled up into the mv_usage_daily materialized view.
Common tasks
Handle a new webhook event: add a handler module/function under services/billing/handlers/, dispatch it from webhook_handler.py, and record it in stripe_event for idempotency (skip if already processed). Verify the signature — never trust unsigned payloads.
Add/adjust a plan: update pricing.py and the corresponding Stripe product/price; the sync-stripe-plans command ({{ cookiecutter.project_slug }} cmd sync-stripe-plans) mirrors Stripe → local plan/price tables.
Charge/grant credits: go through credit_service so every change writes a credit_transaction row (grants, purchases, debits) and the running balance stays consistent. Never mutate balances directly.
Meter usage: write a usage_event (input/output/cached tokens, model, provider, credits charged) — the daily rollup and dashboard charts read from mv_usage_daily (refreshed by a background task).
Local testing
Use the Stripe CLI to forward webhooks: stripe listen --forward-to localhost:8000/api/v1/billing/webhook. Use Stripe test keys/mode. The webhook endpoint is unauthenticated but signature-verified.
Rules
- Routes call
BillingService; never import stripe_client or a sub-service directly from a route.
- Every webhook is idempotent via
stripe_event — re-delivery must be a no-op.
- Credit changes always go through the ledger; the balance is derived, not authoritative state you overwrite.
- Keep Stripe secrets in
settings / .env, never inline.
