feat(billing): send email notification to admin on auto-top-up success

[kilo-code-bot]

Summary

When an auto-top-up is successfully processed (via the invoice.paid Stripe webhook), an email notification is now sent to the relevant admin:

• Personal accounts: the user themselves receives the notification
• Organization accounts: all active org owners receive the notification

The email includes: amount topped up, new balance, which user triggered it, and timestamp. The notification is sent asynchronously via after() to avoid blocking the Stripe webhook response.

Changes:

• New autoTopUpSuccess.html email template following the existing design system
• New sendAutoTopUpSuccessEmail() helper in email.ts
• Notification trigger added to both user and org auto-top-up paths in the invoice.paid webhook handler (stripe.ts)
• Fixture data added for the admin email testing UI
• AGENTS.md email template docs updated
• Fix: processTopupForOrganization() now returns a boolean (true = credits newly applied, false = duplicate/conflict), mirroring the existing processTopUp() pattern. The org notification email is gated on this return value so duplicate invoice.paid webhook retries no longer send spurious emails to org admins.

Verification

• No manual verification was performed — this is a backend-only change to a Stripe webhook handler. The email template can be previewed and test-sent via the admin email testing UI at /admin/email-testing.

Visual Changes

N/A

Reviewer Notes

• The email is only sent when processTopUp / processTopupForOrganization returns successfully (not on duplicate/already-registered cases), matching the pattern where autoTopUpOk / orgAutoTopUpOk is true.
• For the org path, the org's fresh balance is fetched after the credit transaction commits, so new_balance reflects the post-top-up state.
• Error handling wraps the entire email-sending closure in try/catch with captureException — email failures never affect the billing flow.
• The IS_IN_AUTOMATED_TEST guard ensures the email sending runs synchronously in tests (same pattern as credits.ts).
• processedSuccessfully (used for lock management) is still set unconditionally — duplicates should still mark the lock as completed, since the top-up was already processed by a prior webhook.

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Built for Lígia Zanchet by Kilo for Slack

[kilo-code-bot]

WARNING: Duplicate invoice.paid retries can send duplicate org success emails

processTopupForOrganization() currently returns void and just returns early on the onConflictDoNothing() path, so this branch cannot tell whether the org top-up was newly applied or already registered. Stripe retries invoice.paid, and those retries will still queue sendOrgNotification(), which means owners can receive another "Auto Top-Up Successful" email even though no new credits were added. Please return an explicit success boolean here and gate the notification the same way the user path does.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (6 files)

• apps/web/src/emails/AGENTS.md
• apps/web/src/emails/autoTopUpSuccess.html
• apps/web/src/lib/email.ts
• apps/web/src/lib/organizations/organization-billing.ts
• apps/web/src/lib/stripe.ts
• apps/web/src/routers/admin/email-testing-router.ts

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_{Reviewed by gpt-5.4-20260305 · 426,327 tokens}