Send the customer confirmation email from the payment webhook

The webhook route previously assumed the backend's confirm-payment
endpoint sent the customer confirmation email; the backend assumed the
opposite. Net effect: a successful Stripe payment never triggered any
confirmation email. Consume the order snapshot confirm-payment now
returns and send it from here, matching what the checkout route already
does for a manual/Überweisung order.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/api/webhooks/stripe/route.ts

@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server";
 import Stripe from "stripe";
 import { verifyStripeWebhookSignature } from "../../../lib/payments/stripeProvider";
+import { sendConfirmedPaymentEmail, type ConfirmPaymentOrderSnapshot } from "../../../lib/payments/confirmPaymentEmail";
 import { sendCriticalAlert } from "../../../lib/alertAdmin";
 
 const PAYLOAD_URL = process.env.PAYLOAD_URL || "https://payload.mk360.de";
@@ -67,5 +68,17 @@ export async function POST(request: Request) {
     return NextResponse.json({ ok: false }, { status: 502 });
   }
 
+  const data: { ok: boolean; alreadyProcessed?: boolean; order?: ConfirmPaymentOrderSnapshot } = await res.json();
+
+  // Fire-and-forget, same reasoning as the checkout route's own send: a
+  // failed confirmation email must never turn an already-successful
+  // payment confirmation into a non-2xx response (that would make Stripe
+  // retry a webhook we've already fully processed). `alreadyProcessed`/
+  // missing `order` means this is a repeat delivery — see confirmPayment.ts's
+  // own comment on why the email must not be sent twice.
+  if (data.order && !data.alreadyProcessed) {
+    void sendConfirmedPaymentEmail(data.order);
+  }
+
   return NextResponse.json({ ok: true });
 }

app/api/webhooks/stripe/test-confirm/route.ts

@@ -1,5 +1,6 @@
 import { NextResponse } from "next/server";
 import { isPaymentTestMode } from "../../../../lib/payments";
+import { sendConfirmedPaymentEmail, type ConfirmPaymentOrderSnapshot } from "../../../../lib/payments/confirmPaymentEmail";
 import { sendCriticalAlert } from "../../../../lib/alertAdmin";
 
 const PAYLOAD_URL = process.env.PAYLOAD_URL || "https://payload.mk360.de";
@@ -40,5 +41,15 @@ export async function POST(request: Request) {
     return NextResponse.json({ ok: false, reason: "Backend hat die Testzahlung nicht bestätigt." }, { status: 502 });
   }
 
+  const data: { ok: boolean; alreadyProcessed?: boolean; order?: ConfirmPaymentOrderSnapshot } = await res.json();
+
+  // Same email-send as the real webhook route — see its own comment and
+  // confirmPaymentEmail.ts. Reproduces today's "immediate confirmation"
+  // behavior on a test click, exercising the real send path rather than a
+  // separate short-circuit.
+  if (data.order && !data.alreadyProcessed) {
+    void sendConfirmedPaymentEmail(data.order);
+  }
+
   return NextResponse.json({ ok: true });
 }

app/lib/payments/confirmPaymentEmail.ts

@@ -0,0 +1,31 @@
+import { sendOrderConfirmationEmail, type OrderConfirmationEmailData } from "../orderEmail";
+import { sendCriticalAlert } from "../alertAdmin";
+
+// The `order` snapshot returned by the backend's confirm-payment endpoint
+// (see docker/payload's src/lib/endpoints/confirmPayment.ts) — matches
+// OrderConfirmationEmailData minus `customerEmail`, which is passed
+// separately to sendOrderConfirmationEmail. Backend has no SMTP-based
+// order-confirmation sender of its own (only the 4 status-change
+// templates), so it returns everything needed here instead of the
+// frontend needing an authenticated order-read path it doesn't otherwise
+// have (ORDER_SERVICE_SECRET only ever authorizes *creating* an order).
+export type ConfirmPaymentOrderSnapshot = OrderConfirmationEmailData & { customerEmail: string };
+
+// Called from both the real Stripe webhook route and its PAYMENT_TEST_MODE
+// test-confirm sibling, right after confirm-payment reports success (and
+// NOT `alreadyProcessed: true` — a repeat delivery must never resend
+// this). Mirrors exactly what app/api/checkout/route.ts already does for
+// a manual/Überweisung order today, just triggered from the payment
+// webhook instead of the checkout request itself for gated methods.
+export async function sendConfirmedPaymentEmail(order: ConfirmPaymentOrderSnapshot): Promise<void> {
+  const { customerEmail, ...emailData } = order;
+  try {
+    await sendOrderConfirmationEmail(emailData, customerEmail);
+  } catch (err) {
+    sendCriticalAlert("Bestätigungs-Mail konnte nach Zahlungsbestätigung nicht gesendet werden", {
+      orderNumber: order.orderNumber,
+      customerEmail,
+      error: String(err),
+    });
+  }
+}