feat: implement JMAP push notification handling and subscription management

app/api/push/verify/[id]/route.ts

@@ -0,0 +1,34 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { logger } from '@/lib/logger';
+import { subscriptionStore } from '@/lib/push/store';
+import { isValidSubscriptionId } from '@/lib/push/validation';
+
+/**
+ * GET /api/push/verify/:id
+ *
+ * Mobile app polls this after creating a JMAP PushSubscription. When the
+ * JMAP server POSTs a PushVerification to /api/push/jmap/:id we stash the
+ * code on the record; the client then PATCHes the subscription with it and
+ * activation completes (RFC 8620 §7.2.2).
+ */
+export async function GET(
+  _request: NextRequest,
+  { params }: { params: Promise<{ id: string }> },
+) {
+  try {
+    const { id } = await params;
+    if (!isValidSubscriptionId(id)) {
+      return NextResponse.json({ error: 'Invalid subscriptionId' }, { status: 400 });
+    }
+    const record = await subscriptionStore.get(id);
+    if (!record) {
+      return NextResponse.json({ error: 'Unknown subscription' }, { status: 404 });
+    }
+    return NextResponse.json({ verificationCode: record.verificationCode ?? null });
+  } catch (error) {
+    logger.error('push: verify poll failed', {
+      error: error instanceof Error ? error.message : 'Unknown error',
+    });
+    return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
+  }
+}