## Summary
This PR ensures usage alerts are created for all billing scenarios.
## Background
Per [Stripe
documentation](https://docs.stripe.com/billing/subscriptions/usage-based/alerts),
usage alerts are **one-time per customer** - they trigger once and only
consider usage reported after the alert is created. This means we need
to create a new alert whenever:
1. ✅ Subscription is created (trial) - Already implemented
2. ✅ Trial ends (user becomes Active subscriber) - **Added in this PR**
3. ✅ Credit tier changes (upgrade) - **Added in this PR**
4. ✅ **New billing cycle starts** - **Critical fix in this PR!**
## The Issue
Previously, the invoice webhook reset `hasReachedCurrentPeriodCap =
false` at cycle end, but didn't create a new alert. This meant after the
first billing period, there was no alert to trigger and users could
exceed their limit without being blocked.
## Changes
### 1. Invoice Webhook (`billing-webhook-invoice.service.ts`)
When invoice is finalized for `subscription_cycle`:
- Reset `hasReachedCurrentPeriodCap = false` ✅ (already done)
- **NEW**: Create alert at the current tier cap
### 2. End Trial Period (`billing-subscription.service.ts`)
In `endTrialPeriod()`:
- **NEW**: Create alert at the paid tier cap (not trial cap)
### 3. Credit Tier Upgrades (`billing-subscription.service.ts`)
In `changeMeteredPrice()`, when upgrading immediately (not scheduled for
period end):
- **NEW**: Reset `hasReachedCurrentPeriodCap = false`
- **NEW**: Create alert at new tier cap
### 4. Alert Title Update (`stripe-billing-alert.service.ts`)
Changed from "Trial usage cap" to "Usage cap" since alerts are now used
for all scenarios.
## Stripe Alert Limits
- Max 25 alerts per meter+customer combination
- Alerts only evaluate usage reported after creation
- One-time alerts trigger once per customer
With monthly billing cycles + occasional tier changes, we should stay
well under the 25 alert limit.
## Testing
- TypeScript typechecking passes
- Backend services properly inject new dependencies
Félix Malfait
6a4974e285