Email a set-password link when an admin creates a user

src/lib/auth.ts

@@ -5,8 +5,23 @@ import { sveltekitCookies } from 'better-auth/svelte-kit';
 import { getRequestEvent } from '$app/server';
 import { sendMail } from './server/resend';
 import { sendVerificationEmail } from './server/email-verification';
+import { sendRegistrationEmail } from './server/registration-email';
 import { env } from '$env/dynamic/private';
 
+/**
+ * An admin-created user is invited with a set-password link. That reuses the
+ * password-reset token flow but marks the request with `invite=1` so we send a
+ * welcome/registration email instead of a "you requested a reset" email.
+ */
+function isRegistrationInvite(url: string): boolean {
+	try {
+		const callbackURL = new URL(url).searchParams.get('callbackURL') ?? '';
+		return callbackURL.includes('invite=1');
+	} catch {
+		return false;
+	}
+}
+
 export const auth = betterAuth({
 	baseURL: env.BETTER_AUTH_URL,
 	database: prismaAdapter(prisma, {
@@ -27,6 +42,13 @@ export const auth = betterAuth({
 		enabled: true,
 		requireEmailVerification: true,
 		sendResetPassword: async ({ user, url }) => {
+			if (isRegistrationInvite(url)) {
+				void sendRegistrationEmail({ email: user.email, url }).catch((e) => {
+					console.error('sendRegistrationEmail template email failed:', e);
+				});
+				return;
+			}
+
 			void sendMail({
 				to: user.email,
 				templateId: 'password-reset-email',

src/lib/server/registration-email.ts

@@ -0,0 +1,26 @@
+import { env } from '$env/dynamic/private';
+import { sendMail } from './resend';
+
+/**
+ * Send the "finish your registration" email to a user created by an admin.
+ *
+ * The link points at Better Auth's reset-password callback, which redirects to
+ * `/reset-password?invite=1&token=...`. There the user sets a password, then
+ * logs in and is sent to `/profile/setup` to complete their profile.
+ *
+ * Uses a Resend-hosted template (`registration-email` by default, or
+ * `RESEND_REGISTRATION_TEMPLATE_ID`) with variables:
+ *   - `target_email_address`
+ *   - `registration_link`
+ */
+export async function sendRegistrationEmail(options: { email: string; url: string }) {
+	await sendMail({
+		to: options.email,
+		subject: 'Welcome to Radiant Wave — set your password',
+		templateId: env.RESEND_REGISTRATION_TEMPLATE_ID || 'registration-email',
+		data: {
+			target_email_address: options.email,
+			registration_link: options.url
+		}
+	});
+}