An Ash extension for multi-account linking and switching.

Add this extension to your User resource to enable multi-account capabilities. Users can link multiple accounts together and switch between them without re-authenticating — similar to Google/Apple's account switcher UX.

Concepts

• Primary User: The account that initiated the multi-account session
• Linked User: An additional account linked to the primary user
• Session Token: A UUID that groups all linked accounts within a browser session
• Session-scoped: Links exist per browser session, not globally

Usage

defmodule MyApp.Accounts.User do
  use Ash.Resource,
    domain: MyApp.Accounts,
    data_layer: ...,  # any Ash data layer (AshPostgres, AshSqlite, ETS, etc.)
    extensions: [AshMultiAccount]

  multi_account do
    linked_account_resource MyApp.Accounts.LinkedAccount
    display_fields [:name, :email, :avatar_url]
    max_linked_accounts 5
  end
end

Generated Schema

The extension adds to your User resource:

• Calculation :linked_accounts — resolves linked account records for a given session_token argument
• Action :get_user_with_linked_accounts — a get? read action that accepts primary_user_id and session_token arguments, looks up the user by id, loads the configured display_fields, and loads the linked_accounts calculation for the given session

Companion Resource

You must also create a LinkedAccount resource using the AshMultiAccount.LinkedAccount extension. See its documentation for details.