diff --git a/loko/interventions/templates/interventions/detail/card_chronologie.html b/loko/interventions/templates/interventions/detail/card_chronologie.html
index 0771ec2..f4c6288 100644
--- a/loko/interventions/templates/interventions/detail/card_chronologie.html
+++ b/loko/interventions/templates/interventions/detail/card_chronologie.html
@@ -13,7 +13,8 @@
             </span>
         </div>
 
-        <!-- Filtre mode d'affichage -->
+        <!-- Filtre mode d'affichage (réservé aux agents internes) -->
+        {% if is_user_intern %}
         <div class="d-flex align-items-center gap-2">
             <div class="btn-group btn-group-sm" role="group" aria-label="{% translate 'Filtrer l\'historique' %}">
                 <button type="button"
@@ -35,6 +36,7 @@
                 </button>
             </div>
         </div>
+        {% endif %}
     </div>
 
     <div class="card-body p-3">
@@ -42,6 +44,7 @@
         {% if events_list %}
         <div class="history-timeline">
             {% for event in events_list %}
+            {% if is_user_intern or event.is_default_visible %}
             <div class="history-timeline-item {% if not event.is_default_visible %}history-item-detailed history-item-modification d-none{% endif %}"
                  data-event-type="{{ event.event_type }}">
                 <!-- Node Icon -->
@@ -144,6 +147,7 @@
                     {% endif %}
                 </div>
             </div>
+            {% endif %}
             {% endfor %}
         </div>
         {% else %}
diff --git a/loko/interventions/tests/test_timeline_history.py b/loko/interventions/tests/test_timeline_history.py
index 27e0c93..faa734d 100644
--- a/loko/interventions/tests/test_timeline_history.py
+++ b/loko/interventions/tests/test_timeline_history.py
@@ -477,5 +477,47 @@ class TimelineHistoryTests(TestCase):
         self.assertContains(response, 'history-status-circle')
         self.assertContains(response, 'history-status-transition')
         self.assertContains(response, 'bg-purple')
+        self.assertContains(response, 'id="btnHistoryFull"')
+
+    def test_detail_view_hides_full_history_for_external_user(self):
+        """Test that external users (is_intern=False) do NOT see full history or detailed modification/note events."""
+        User = get_user_model()
+        ext_user = User.objects.create_user(
+            username='prestataire_ext',
+            password='secret_password',
+            first_name='Pierre',
+            last_name='Martin'
+        )
+        ext_config = UserConfig.objects.create(user=ext_user, is_intern=False)
+        ext_role, _ = Role.objects.get_or_create(name='external_manager')
+        ext_config.roles.add(ext_role)
+        self.intervention.assigned_provider = self.company
+        self.intervention.save()
+
+        record_timeline_event(self.intervention, self.user, event_type='status_change', from_status='in_preparation', to_status='to_be_processed')
+        record_note_event(self.intervention, self.user, action='create', note_type='comment', content='Note interne confidentielle')
+        record_document_event(self.intervention, self.user, action='upload', filenames=['secret_doc.pdf'])
+
+        self.client.login(username='prestataire_ext', password='secret_password')
+        url = reverse('interventions:intervention_detail', args=[self.intervention.id])
+        response = self.client.get(url)
+        self.assertEqual(response.status_code, 200)
+
+        # Le filtre "Historique complet" ne doit PAS être affiché
+        self.assertNotContains(response, 'id="btnHistoryFull"')
+        self.assertNotContains(response, 'id="btnHistoryDefault"')
+
+        # Aucun événement détaillé n'est dans le contexte
+        self.assertEqual(response.context['timeline_detailed_count'], 0)
+        self.assertTrue(all(e.is_default_visible for e in response.context['timeline_events']))
+
+        # Le contenu confidentiel des notes et documents n'est pas transmis dans l'historique
+        self.assertNotContains(response, 'Note interne confidentielle')
+        self.assertNotContains(response, 'secret_doc.pdf')
+
+        # Les statuts et assignations restent parfaitement visibles
+        self.assertContains(response, 'history-status-circle')
+        self.assertContains(response, 'history-status-transition')
+
 
 
diff --git a/loko/interventions/views/detail.py b/loko/interventions/views/detail.py
index 0c8eb03..7a0adfe 100644
--- a/loko/interventions/views/detail.py
+++ b/loko/interventions/views/detail.py
@@ -682,6 +682,13 @@ def intervention_detail(request, intervention_id):
         insert_idx = 1 if (timeline_events and timeline_events[0].is_creation) else 0
         timeline_events.insert(insert_idx, synth_event)
 
+    # Sécurité / Confidentialité : l'historique complet (modifications d'attributs, notes, documents, liens)
+    # est strictement réservé aux agents internes.
+    # Les utilisateurs externes (prestataires) ne reçoivent que le flux opérationnel
+    # (statuts, assignations, créations, transferts).
+    if not is_user_intern:
+        timeline_events = [e for e in timeline_events if e.is_default_visible]
+
     timeline_default_count = sum(1 for e in timeline_events if e.is_default_visible)
     timeline_detailed_count = sum(1 for e in timeline_events if not e.is_default_visible)
     timeline_modification_count = timeline_detailed_count