diff --git a/server/shell.ts b/server/shell.ts
index 5af447f..de58189 100644
--- a/server/shell.ts
+++ b/server/shell.ts
@@ -871,7 +871,7 @@ export function renderShell(opts: ShellOptions): string {
         if (_tabChannel) _tabChannel.close();
       });
 
-      // Fetch tabs from server for authenticated users (merge with localStorage)
+      // Fetch tabs from server for authenticated users (server-authoritative)
       (function syncTabsFromServer() {
         try {
           const raw = localStorage.getItem('encryptid_session');
@@ -888,21 +888,17 @@ export function renderShell(opts: ShellOptions): string {
                 saveTabs();
                 return;
               }
-              // Merge: union of moduleIds, server order wins for shared tabs
-              // Skip tabs that were closed this session (prevents resurrection)
-              const serverMap = new Map(data.tabs.map(t => [t.moduleId, t]));
-              const localMap = new Map(layers.map(t => [t.moduleId, t]));
-              const merged = data.tabs.filter(t => !_closedModuleIds.has(t.moduleId));
-              for (const [mid, lt] of localMap) {
-                if (!serverMap.has(mid) && !_closedModuleIds.has(mid)) merged.push(lt);
-              }
-              merged.forEach((l, i) => { l.order = i; });
-              layers = merged;
-              // Ensure current module is present
+              // Server-authoritative: adopt server tabs exactly.
+              // Only skip tabs the user closed in THIS session (prevents
+              // close-then-immediate-resurrect before save propagates).
+              var serverTabs = data.tabs.filter(t => !_closedModuleIds.has(t.moduleId));
+              serverTabs.forEach((l, i) => { l.order = i; });
+              layers = serverTabs;
+              // Ensure the currently navigated module is present
               if (!layers.find(l => l.moduleId === currentModuleId)) {
                 layers.push(makeLayer(currentModuleId, layers.length));
               }
-              tabBar.setLayers(layers);
+              reconcileRemoteLayers(layers);
               saveTabs();
             })
             .catch(() => {});
@@ -1455,7 +1451,44 @@ export function renderExternalAppShell(opts: ExternalAppShellOptions): string {
       tabBar.setLayers(layers);
       tabBar.setAttribute('active', 'layer-' + currentModuleId);
       if (tabBar.trackRecent) tabBar.trackRecent(currentModuleId);
-      function saveTabs() { localStorage.setItem(TABS_KEY, JSON.stringify(layers)); }
+      function saveTabs() {
+        localStorage.setItem(TABS_KEY, JSON.stringify(layers));
+        try {
+          var raw = localStorage.getItem('encryptid_session');
+          if (raw) {
+            var session = JSON.parse(raw);
+            if (session?.accessToken) {
+              fetch('/api/user/tabs/' + encodeURIComponent(spaceSlug), {
+                method: 'PUT',
+                headers: { 'Content-Type': 'application/json', 'Authorization': 'Bearer ' + session.accessToken },
+                body: JSON.stringify({ tabs: layers }),
+              }).catch(function(){});
+            }
+          }
+        } catch(e) {}
+      }
+      // Sync tabs from server (server-authoritative)
+      (function() {
+        try {
+          var raw = localStorage.getItem('encryptid_session');
+          if (!raw) return;
+          var session = JSON.parse(raw);
+          if (!session?.accessToken) return;
+          fetch('/api/user/tabs/' + encodeURIComponent(spaceSlug), {
+            headers: { 'Authorization': 'Bearer ' + session.accessToken },
+          })
+            .then(function(r) { return r.ok ? r.json() : null; })
+            .then(function(data) {
+              if (!data?.tabs || !Array.isArray(data.tabs) || data.tabs.length === 0) { saveTabs(); return; }
+              layers = data.tabs;
+              layers.forEach(function(l, i) { l.order = i; });
+              if (!layers.find(function(l) { return l.moduleId === currentModuleId; })) layers.push(makeLayer(currentModuleId, layers.length));
+              tabBar.setLayers(layers);
+              localStorage.setItem(TABS_KEY, JSON.stringify(layers));
+            })
+            .catch(function(){});
+        } catch(e) {}
+      })();
       tabBar.addEventListener('layer-switch', (e) => { saveTabs(); window.location.href = window.__rspaceNavUrl(spaceSlug, e.detail.moduleId); });
       tabBar.addEventListener('layer-add', (e) => { const { moduleId } = e.detail; if (!layers.find(l => l.moduleId === moduleId)) layers.push(makeLayer(moduleId, layers.length)); saveTabs(); window.location.href = window.__rspaceNavUrl(spaceSlug, moduleId); });
       tabBar.addEventListener('layer-close', (e) => { const { layerId } = e.detail; tabBar.removeLayer(layerId); layers = layers.filter(l => l.id !== layerId); saveTabs(); if (layerId === 'layer-' + currentModuleId && layers.length > 0) window.location.href = window.__rspaceNavUrl(spaceSlug, layers[0].moduleId); });