add action changes for email sync

lib/accounts/user.ex

@@ -89,6 +89,9 @@ defmodule Mv.Accounts.User do
       # cannot be executed atomically. These validations need to query the database and perform
       # complex checks that are not supported in atomic operations.
       require_atomic? false
+
+      # Sync email changes to linked member
+      change Mv.Accounts.User.Changes.SyncEmailToMember
     end
 
     create :create_user do
@@ -111,6 +114,9 @@ defmodule Mv.Accounts.User do
                # If no member provided, that's fine (optional relationship)
                on_missing: :ignore
              )
+
+      # Override member email with user email when linking
+      change Mv.Accounts.User.Changes.OverrideMemberEmailOnLink
     end
 
     update :update_user do
@@ -137,6 +143,11 @@ defmodule Mv.Accounts.User do
                # If no member provided, remove existing relationship (allows member removal)
                on_missing: :unrelate
              )
+
+      # Sync email changes to linked member
+      change Mv.Accounts.User.Changes.SyncEmailToMember
+      # Override member email with user email when linking
+      change Mv.Accounts.User.Changes.OverrideMemberEmailOnLink
     end
 
     # Admin action for direct password changes in admin panel
@@ -185,6 +196,9 @@ defmodule Mv.Accounts.User do
         |> Ash.Changeset.change_attribute(:email, user_info["preferred_username"])
         |> Ash.Changeset.change_attribute(:oidc_id, user_info["sub"] || user_info["id"])
       end
+
+      # Override member email with user email when linking (if member relationship exists)
+      change Mv.Accounts.User.Changes.OverrideMemberEmailOnLink
     end
   end
 
@@ -255,6 +269,14 @@ defmodule Mv.Accounts.User do
   attributes do
     uuid_primary_key :id
 
+    # IMPORTANT: Email Synchronization
+    # When user and member are linked, emails are automatically synced bidirectionally.
+    # User.email is the source of truth - when a link is established, member.email
+    # is overridden to match user.email. Subsequent changes to either email will
+    # sync to the other resource.
+    # See: Mv.Accounts.User.Changes.SyncEmailToMember
+    #      Mv.Accounts.User.Changes.OverrideMemberEmailOnLink
+    #      Mv.Membership.Member.Changes.SyncEmailToUser
     attribute :email, :ci_string do
       allow_nil? false
       public? true