Fix Cancel Subscription failure by adding Stripe customer lookup fallback

[Copilot]

CancelSubscriptionAtPeriodEnd exclusively relied on finding an inactive Invitation record by email to resolve the Stripe subscription ID. Members without a matching inactive invitation (pre-invitation-system members, admin-provisioned accounts, cleaned-up records, or invitations with an empty PaymentHandlerSubscriptionId) would always throw, surfacing as "Attempt to cancel subscription failed."

Changes

• StripePaymentHandlerSubscriptionService
  • Inject CustomerService (already registered in DI)
  • Extract GetSubscriptionIdForEmailAsync with two-stage resolution:
    1. Primary: existing invitation table lookup
    2. Fallback: Stripe customer lookup by email → active subscription, when invitation is missing or has no subscription ID
  • Switch Update/List calls to their async variants (UpdateAsync, ListAsync)
  • Log a warning when the fallback path is taken

private async Task<string> GetSubscriptionIdForEmailAsync(string customerEmail)
{
    var invite = await _invitationRepository.FirstOrDefaultAsync(
        new InactiveInvitationByEmailSpec(customerEmail));

    if (invite != null && !string.IsNullOrEmpty(invite.PaymentHandlerSubscriptionId))
        return invite.PaymentHandlerSubscriptionId;

    _logger.LogWarning($"No inactive invitation with a valid subscription ID found for {customerEmail}. Falling back to Stripe customer lookup.");

    var customers = await _customerService.ListAsync(new CustomerListOptions { Email = customerEmail.ToLower(), Limit = 1 });
    if (customers.Data.Count == 0) throw new InvitationNotFoundException(customerEmail);

    var subscriptions = await _subscriptionService.ListAsync(new SubscriptionListOptions
        { Customer = customers.Data[0].Id, Status = "active", Limit = 1 });
    if (subscriptions.Data.Count == 0) throw new InvitationNotFoundException(customerEmail);

    return subscriptions.Data[0].Id;
}

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• api.cdnjs.com
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet /usr/share/dotnet/sdk/10.0.102/MSBuild.dll /noautoresponse /nologo /nodemode:1 /nodeReuse:false /low:false _TOKEN"; }; f (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet /usr/share/dotnet/sdk/10.0.102/MSBuild.dll /noautoresponse /nologo /nodemode:1 /nodeReuse:false /low:false ep/bin/linux-x64/rg (dns block)
  • Triggering command: /usr/bin/dotnet dotnet build tests/DevBetterWeb.Tests/DevBetterWeb.Tests.csproj (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Error: Cancel Subscription</issue_title>
<issue_description>In the member portal, under My Profile: Cancel Subscription, there's a client side error preventing the behavior from working properly.

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Error: Cancel Subscription #1394

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.