Magic Link not working with InstantDB (better-auth-instantdb)

export const auth = betterAuth({
  appName: APP_NAME,
  secret: envVariables.BETTER_AUTH_SECRET,
  baseURL: import.meta.env.VITE_BASE_URL || "http://localhost:3000",
  database: instantDBAdapter({
    db: instantServerDB,
    usePlural: true, // Our schema uses plural form
    debugLogs: true, // Enable debug logs to trace issues
  }),
  trustedOrigins: [
    "http://localhost:3000",
    "http://localhost:3001",
    "https://moneymouth.ai",
    ...(import.meta.env.VITE_BASE_URL ? [import.meta.env.VITE_BASE_URL] : []),
  ],
  plugins: [
    magicLink({
      // Auto-create users when they use magic links
      disableSignUp: false,
      expiresIn: 60 * 60 * 24 * 365 * 100, // 100 years in seconds
      sendMagicLink: async ({ email, token, url }, request) => {
        console.log("🔗 Magic link handler started");
        console.log("🔗 Email:", email);
        console.log("🔗 Token:", token);
        console.log("🔗 URL:", url);

        // Send the ebook email with magic link
        await sendEbookEmail({ email, token, url });

        console.log("📧 Magic link email sent successfully to:", email);
      },
    }),
  ],
  user: {
    changeEmail: {
      enabled: true,
    },
    deleteUser: {
      enabled: true,
    },
  },
});

export const auth = betterAuth({
  appName: APP_NAME,
  secret: envVariables.BETTER_AUTH_SECRET,
  baseURL: import.meta.env.VITE_BASE_URL || "http://localhost:3000",
  database: instantDBAdapter({
    db: instantServerDB,
    usePlural: true, // Our schema uses plural form
    debugLogs: true, // Enable debug logs to trace issues
  }),
  trustedOrigins: [
    "http://localhost:3000",
    "http://localhost:3001",
    "https://moneymouth.ai",
    ...(import.meta.env.VITE_BASE_URL ? [import.meta.env.VITE_BASE_URL] : []),
  ],
  plugins: [
    magicLink({
      // Auto-create users when they use magic links
      disableSignUp: false,
      expiresIn: 60 * 60 * 24 * 365 * 100, // 100 years in seconds
      sendMagicLink: async ({ email, token, url }, request) => {
        console.log("🔗 Magic link handler started");
        console.log("🔗 Email:", email);
        console.log("🔗 Token:", token);
        console.log("🔗 URL:", url);

        // Send the ebook email with magic link
        await sendEbookEmail({ email, token, url });

        console.log("📧 Magic link email sent successfully to:", email);
      },
    }),
  ],
  user: {
    changeEmail: {
      enabled: true,
    },
    deleteUser: {
      enabled: true,
    },
  },
});

The error $users entity not found: d5ac689d-f713-4ddb-a666-7cb42c8adcb1 occurs when Better Auth tries to create a session after successfully verifying the magic link. Here's what's happening:
Magic link verification works - the user's emailVerified is successfully updated to true
Session creation fails - when trying to create a session, the adapter looks for a user in the $users entity, but can't find one with that ID
Root Cause
Looking at your schema, you have a dual entity system:
$users - InstantDB's system entity for authentication
users - Your application entity for user data
The issue is that when the @daveyplate/better-auth-instantdb adapter creates a session, it needs to reference the user ID, but there's a mismatch between which entity it's looking for the user in.

The error $users entity not found: d5ac689d-f713-4ddb-a666-7cb42c8adcb1 occurs when Better Auth tries to create a session after successfully verifying the magic link. Here's what's happening:
Magic link verification works - the user's emailVerified is successfully updated to true
Session creation fails - when trying to create a session, the adapter looks for a user in the $users entity, but can't find one with that ID
Root Cause
Looking at your schema, you have a dual entity system:
$users - InstantDB's system entity for authentication
users - Your application entity for user data
The issue is that when the @daveyplate/better-auth-instantdb adapter creates a session, it needs to reference the user ID, but there's a mismatch between which entity it's looking for the user in.

  const newUserId = id();

  // Create new $users record
  await instantServerDB.transact(
    instantServerDB.tx.$users[newUserId].update({
      email,
    }),
  );

  const newUserId = id();

  // Create new $users record
  await instantServerDB.transact(
    instantServerDB.tx.$users[newUserId].update({
      email,
    }),
  );