diff --git a/app/templates/_header.html b/app/templates/_header.html
index 3bc2933..3079bb1 100644
--- a/app/templates/_header.html
+++ b/app/templates/_header.html
@@ -6,18 +6,6 @@
    Page active : `active_nav` (déduite du gabarit dans render()).
    Fil d'Ariane : `owner`+`repo` (board) ou `full_name` (projet).
    Le wallboard (TV) n'inclut pas ce partiel, volontairement. #}
-<script>
-    document.body.classList.add('with-sidebar');
-    try {
-        if (localStorage.getItem('kanbante-sidebar') === 'collapsed') {
-            document.body.classList.add('sidebar-collapsed');
-        }
-        JSON.parse(localStorage.getItem('kanbante-nav-closed') || '[]')
-            .forEach(function (k) {
-                document.body.classList.add('nav-closed-' + k);
-            });
-    } catch (e) { /* stockage indisponible : état par défaut */ }
-</script>
 {% set nav_groups = [
     ("principal", "Principal", [
         ("home", "/", "🏠", "Projets"),
@@ -42,6 +30,37 @@
         ("wall", "/wall", "🖥️", "Wallboard"),
     ]),
 ] %}
+{% set active_group = namespace(key="principal") %}
+{% for gkey, group, links in nav_groups %}
+    {% for key, href, icon, label in links %}
+        {% if active_nav == key %}{% set active_group.key = gkey %}{% endif %}
+    {% endfor %}
+{% endfor %}
+<script>
+    document.body.classList.add('with-sidebar');
+    try {
+        if (localStorage.getItem('kanbante-sidebar') === 'collapsed') {
+            document.body.classList.add('sidebar-collapsed');
+        }
+        /* Accordéon exclusif (0.22.0) : une seule section ouverte.
+           La section de la page courante prime, sinon celle
+           mémorisée, sinon « principal ». */
+        localStorage.removeItem('kanbante-nav-closed');
+        var openGroup = {{ active_group.key | tojson }};
+        var stored = localStorage.getItem('kanbante-nav-open');
+        var groups = ['principal', 'rituels', 'pilotage', 'outils'];
+        if ({{ (active_nav != "") | tojson }}) {
+            localStorage.setItem('kanbante-nav-open', openGroup);
+        } else if (stored === '') {
+            openGroup = '';
+        } else if (stored !== null && groups.indexOf(stored) >= 0) {
+            openGroup = stored;
+        }
+        groups.forEach(function (k) {
+            if (k !== openGroup) document.body.classList.add('nav-closed-' + k);
+        });
+    } catch (e) { /* stockage indisponible : état par défaut */ }
+</script>
 <aside class="sidebar" id="sidebar" aria-label="Navigation principale">
     <div class="side-head">
         <a href="/" class="side-logo" aria-label="Kanbante — accueil">
@@ -49,6 +68,7 @@
             <span class="side-label gradient-text">Kanbante</span>
         </a>
         <button type="button" class="side-search palette-trigger" title="Recherche & commandes (Ctrl+K)" aria-label="Recherche et commandes (Ctrl+K)">🔍</button>
+        <button type="button" class="side-collapse" id="side-collapse" title="Replier ou déplier le menu" aria-label="Replier ou déplier le menu"><span class="side-collapse-ico">«</span></button>
     </div>
     <nav class="side-nav">
         {% for gkey, group, links in nav_groups %}
@@ -71,11 +91,13 @@
         {% endfor %}
     </nav>
     <div class="side-foot">
-        <button type="button" class="side-collapse" id="side-collapse" aria-label="Replier ou déplier le menu">
-            <span class="side-collapse-ico">«</span>
-            <span class="side-label">Replier</span>
-        </button>
+        {% if data_freshness %}
+        <span class="side-fresh side-label" title="Dernière actualisation des données Gitea (instantanés d'arrière-plan)">🕐 {{ data_freshness }}</span>
+        {% endif %}
         <span class="side-version side-label">v{{ version }}</span>
+        {% if auth_enabled %}
+        <a href="/logout" class="side-logout" title="Se déconnecter">⏻<span class="side-label"> Sortir</span></a>
+        {% endif %}
     </div>
 </aside>
 <div class="side-backdrop" id="side-backdrop" hidden></div>
diff --git a/static/js/nav.js b/static/js/nav.js
index dcdb1d3..29e2622 100644
--- a/static/js/nav.js
+++ b/static/js/nav.js
@@ -43,46 +43,33 @@
         });
     }
 
-    /* Accordion sections: the closed set lives in body classes
-       (applied pre-paint by the bootstrap script in _header.html)
-       and is persisted here on every toggle. */
+    /* Accordéon EXCLUSIF (0.22.0) : une seule section ouverte
+       à la fois. Ouvrir une section ferme les autres ; cliquer
+       la section ouverte la referme. L'état initial vient du
+       script d'amorce de _header.html (section de la page
+       courante ou choix mémorisé dans kanbante-nav-open). */
     var groupBtns = document.querySelectorAll('[data-group-btn]');
-    function persistClosedGroups() {
-        var closed = [];
-        groupBtns.forEach(function (btn) {
-            if (document.body.classList.contains('nav-closed-' + btn.getAttribute('data-group-btn'))) {
-                closed.push(btn.getAttribute('data-group-btn'));
-            }
-        });
-        try {
-            localStorage.setItem('kanbante-nav-closed', JSON.stringify(closed));
-        } catch (e) { /* non-fatal */ }
-    }
     function syncGroupBtn(btn) {
         var closed = document.body.classList.contains(
             'nav-closed-' + btn.getAttribute('data-group-btn'));
         btn.setAttribute('aria-expanded', closed ? 'false' : 'true');
     }
+    function setOpenGroup(openKey) {
+        groupBtns.forEach(function (btn) {
+            var key = btn.getAttribute('data-group-btn');
+            document.body.classList.toggle('nav-closed-' + key, key !== openKey);
+            syncGroupBtn(btn);
+        });
+        try {
+            localStorage.setItem('kanbante-nav-open', openKey);
+        } catch (e) { /* non-fatal */ }
+    }
     groupBtns.forEach(function (btn) {
         syncGroupBtn(btn);
         btn.addEventListener('click', function () {
-            document.body.classList.toggle(
-                'nav-closed-' + btn.getAttribute('data-group-btn'));
-            syncGroupBtn(btn);
-            persistClosedGroups();
+            var key = btn.getAttribute('data-group-btn');
+            var isOpen = !document.body.classList.contains('nav-closed-' + key);
+            setOpenGroup(isOpen ? '' : key);
         });
     });
-    /* The section holding the current page is always opened. */
-    var activeLink = document.querySelector('.sidebar .side-link.active');
-    if (activeLink) {
-        var section = activeLink.closest('.side-section');
-        if (section) {
-            var key = section.getAttribute('data-group');
-            if (document.body.classList.contains('nav-closed-' + key)) {
-                document.body.classList.remove('nav-closed-' + key);
-                groupBtns.forEach(syncGroupBtn);
-                persistClosedGroups();
-            }
-        }
-    }
 })();