feat(auth): @mosaic/auth — BetterAuth email/password setup (#68)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

packages/auth/src/auth.ts

@@ -0,0 +1,42 @@
+import { betterAuth } from 'better-auth';
+import { drizzleAdapter } from 'better-auth/adapters/drizzle';
+import type { Db } from '@mosaic/db';
+
+export interface AuthConfig {
+  db: Db;
+  baseURL?: string;
+  secret?: string;
+}
+
+export function createAuth(config: AuthConfig) {
+  const { db, baseURL, secret } = config;
+
+  return betterAuth({
+    database: drizzleAdapter(db, {
+      provider: 'pg',
+      usePlural: true,
+    }),
+    baseURL: baseURL ?? process.env['BETTER_AUTH_URL'] ?? 'http://localhost:4000',
+    secret: secret ?? process.env['BETTER_AUTH_SECRET'],
+    basePath: '/api/auth',
+    emailAndPassword: {
+      enabled: true,
+    },
+    user: {
+      additionalFields: {
+        role: {
+          type: 'string',
+          required: false,
+          defaultValue: 'member',
+          input: false,
+        },
+      },
+    },
+    session: {
+      expiresIn: 60 * 60 * 24 * 7, // 7 days
+      updateAge: 60 * 60 * 24, // refresh daily
+    },
+  });
+}
+
+export type Auth = ReturnType<typeof createAuth>;