refactor: email sync changes

lib/membership/member.ex

@@ -49,8 +49,11 @@ defmodule Mv.Membership.Member do
                on_missing: :ignore
              )
 
-      # Override member email with user email when linking
-      change Mv.Membership.Member.Changes.OverrideEmailFromUserOnLink
+      # Sync user email to member when linking (User → Member)
+      # Only runs when user relationship is being changed
+      change Mv.EmailSync.Changes.SyncUserEmailToMember do
+        where [changing(:user)]
+      end
     end
 
     update :update_member do
@@ -93,10 +96,17 @@ defmodule Mv.Membership.Member do
                on_missing: :unrelate
              )
 
-      # Override member email with user email when linking
-      change Mv.Membership.Member.Changes.OverrideEmailFromUserOnLink
-      # Sync email changes to linked user
-      change Mv.Membership.Member.Changes.SyncEmailToUser
+      # Sync member email to user when email changes (Member → User)
+      # Only runs when email is being changed
+      change Mv.EmailSync.Changes.SyncMemberEmailToUser do
+        where [changing(:email)]
+      end
+
+      # Sync user email to member when linking (User → Member)
+      # Only runs when user relationship is being changed
+      change Mv.EmailSync.Changes.SyncUserEmailToMember do
+        where [changing(:user)]
+      end
     end
   end
 
@@ -206,9 +216,8 @@ defmodule Mv.Membership.Member do
     # 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.Membership.Member.Changes.SyncEmailToUser
-    #      Mv.Membership.Member.Changes.OverrideEmailFromUserOnLink
-    #      Mv.Accounts.User.Changes.SyncEmailToMember
+    # See: Mv.EmailSync.Changes.SyncUserEmailToMember
+    #      Mv.EmailSync.Changes.SyncMemberEmailToUser
     attribute :email, :string do
       allow_nil? false
       constraints min_length: 5, max_length: 254