The email delivery engine engineered for Lucia Auth v3 & Oslo in modern TypeScript apps

import { createDate, TimeSpan } from 'oslo';
import { generateRandomString, alphabet } from 'oslo/crypto';
import { SadaSend } from 'sadasend';
import { db } from '@/lib/db';

const sadasend = new SadaSend({
  apiKey: process.env.SADASEND_API_KEY!,
});

export async function createAndSendEmailVerification(userId: string, email: string) {
  // 1. Generate 8-character verification token using Oslo
  const tokenId = generateRandomString(8, alphabet('0-9', 'A-Z'));
  const expiresAt = createDate(new TimeSpan(15, 'm')); // 15-minute TTL

  // 2. Persist verification token in your database
  await db.emailVerificationToken.create({
    data: { id: tokenId, userId, expiresAt },
  });

  // 3. Dispatch verification email in sub-150ms with in-flight bounce defense
  const result = await sadasend.emails.send({
    from: 'auth@yourdomain.com',
    to: email,
    subject: 'Verify your account',
    html: `<p>Your verification code is <strong>${tokenId}</strong>. It expires in 15 minutes.</p>`,
    verifyBeforeSend: true, // Rejects typos and dead domains before debiting quota
    tags: ['auth', 'email-verification'],
  });

  return { tokenId, messageId: result.id };
}