diff --git a/app/components/attachment/gallery_item_component.rb b/app/components/attachment/gallery_item_component.rb
index 0aa3e766f..3319ad3d9 100644
--- a/app/components/attachment/gallery_item_component.rb
+++ b/app/components/attachment/gallery_item_component.rb
@@ -30,6 +30,8 @@ class Attachment::GalleryItemComponent < ApplicationComponent
     case
     when from_dossier?
       'Dossier usager'
+    when from_messagerie_expert?
+      'Messagerie (expert)'
     when from_messagerie_instructeur?
       'Messagerie (instructeur)'
     when from_messagerie_usager?
@@ -90,8 +92,12 @@ class Attachment::GalleryItemComponent < ApplicationComponent
     from_messagerie? && attachment.record.instructeur.present?
   end
 
+  def from_messagerie_expert?
+    from_messagerie? && attachment.record.expert.present?
+  end
+
   def from_messagerie_usager?
-    from_messagerie? && attachment.record.instructeur.nil?
+    from_messagerie? && attachment.record.instructeur.nil? && attachment.record.expert.nil?
   end
 
   def from_avis_externe?
diff --git a/app/controllers/experts/avis_controller.rb b/app/controllers/experts/avis_controller.rb
index 6d9d737e8..f994f0e50 100644
--- a/app/controllers/experts/avis_controller.rb
+++ b/app/controllers/experts/avis_controller.rb
@@ -167,7 +167,11 @@ module Experts
       @commentaire = CommentaireService.create(current_expert, avis.dossier, commentaire_params)
 
       if @commentaire.errors.empty?
-        @commentaire.dossier.update!(last_commentaire_updated_at: Time.zone.now)
+        timestamps = [:last_commentaire_updated_at, :updated_at]
+        timestamps << :last_commentaire_piece_jointe_updated_at if @commentaire.piece_jointe.attached?
+
+        @commentaire.dossier.touch(*timestamps)
+
         flash.notice = "Message envoyé"
         redirect_to messagerie_expert_avis_path(avis.procedure, avis)
       else
diff --git a/spec/components/attachment/gallery_item_component_spec.rb b/spec/components/attachment/gallery_item_component_spec.rb
index 172ed0574..e9fda3802 100644
--- a/spec/components/attachment/gallery_item_component_spec.rb
+++ b/spec/components/attachment/gallery_item_component_spec.rb
@@ -100,6 +100,14 @@ RSpec.describe Attachment::GalleryItemComponent, type: :component do
         expect(subject).to have_text('Messagerie (instructeur)')
       end
     end
+
+    context 'from an expert' do
+      let(:expert) { create(:expert) }
+      before { commentaire.update!(expert:) }
+      it "displays the right tag" do
+        expect(subject).to have_text('Messagerie (expert)')
+      end
+    end
   end
 
   context "when attachment is from an avis" do