diff --git a/server/shell.ts b/server/shell.ts
index ac28b36d..58acb41d 100644
--- a/server/shell.ts
+++ b/server/shell.ts
@@ -871,6 +871,9 @@ export function renderShell(opts: ShellOptions): string {
         };
       }
 
+      // Valid module IDs for this space (used to filter out stale/phantom tabs)
+      const validModuleIds = new Set(moduleList.map(m => m.id));
+
       // ── Restore tabs from localStorage ──
       let layers;
       try {
@@ -879,12 +882,15 @@ export function renderShell(opts: ShellOptions): string {
         if (!Array.isArray(layers)) layers = [];
       } catch(e) { layers = []; }
 
+      // Filter out stale tabs whose moduleId no longer exists
+      layers = deduplicateLayers(layers.filter(l => validModuleIds.has(l.moduleId)));
+
       // Ensure the current module is in the tab list
       if (!layers.find(l => l.moduleId === currentModuleId)) {
         layers.push(makeLayer(currentModuleId, layers.length));
       }
 
-      // Persist immediately (includes the newly-added tab)
+      // Persist immediately (cleaned list)
       localStorage.setItem(TABS_KEY, JSON.stringify(layers));
 
       // Render all tabs with the current one active
@@ -954,7 +960,7 @@ export function renderShell(opts: ShellOptions): string {
           if (!next.has(mid) && tabCache) tabCache.removePane(mid);
         }
 
-        layers = deduplicateLayers(remoteLayers);
+        layers = deduplicateLayers(remoteLayers.filter(l => validModuleIds.has(l.moduleId)));
 
         // Always ensure the current module stays in the tab list
         if (currentModuleId && !layers.find(l => l.moduleId === currentModuleId)) {
@@ -1001,7 +1007,8 @@ export function renderShell(opts: ShellOptions): string {
               // 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));
+              var serverTabs = data.tabs.filter(t => validModuleIds.has(t.moduleId) && !_closedModuleIds.has(t.moduleId));
+              serverTabs = deduplicateLayers(serverTabs);
               serverTabs.forEach((l, i) => { l.order = i; });
               layers = serverTabs;
               // Ensure the currently navigated module is present
@@ -1711,6 +1718,7 @@ export function renderExternalAppShell(opts: ExternalAppShellOptions): string {
 
     if (tabBar) {
       tabBar.setModules(moduleList);
+      const validModuleIds = new Set(moduleList.map(m => m.id));
       function getModuleLabel(id) {
         const m = moduleList.find(mod => mod.id === id);
         return m ? m.name : id;
@@ -1718,13 +1726,20 @@ export function renderExternalAppShell(opts: ExternalAppShellOptions): string {
       function makeLayer(id, order) {
         return { id: 'layer-' + id, moduleId: id, label: getModuleLabel(id), order, color: '', visible: true, createdAt: Date.now() };
       }
+      function deduplicateLayers(list) {
+        const seen = new Set();
+        return list.filter(l => { if (seen.has(l.moduleId)) return false; seen.add(l.moduleId); return true; });
+      }
       let layers;
       try { const saved = localStorage.getItem(TABS_KEY); layers = saved ? JSON.parse(saved) : []; if (!Array.isArray(layers)) layers = []; } catch(e) { layers = []; }
+      // Filter out stale/phantom tabs and deduplicate
+      layers = deduplicateLayers(layers.filter(l => validModuleIds.has(l.moduleId)));
       if (!layers.find(l => l.moduleId === currentModuleId)) layers.push(makeLayer(currentModuleId, layers.length));
       localStorage.setItem(TABS_KEY, JSON.stringify(layers));
       tabBar.setLayers(layers);
       tabBar.setAttribute('active', 'layer-' + currentModuleId);
       if (tabBar.trackRecent) tabBar.trackRecent(currentModuleId);
+      const _closedModuleIds = new Set();
       function saveTabs() {
         localStorage.setItem(TABS_KEY, JSON.stringify(layers));
         try {
@@ -1754,7 +1769,8 @@ export function renderExternalAppShell(opts: ExternalAppShellOptions): string {
             .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;
+              // Filter stale moduleIds and tabs closed this session
+              layers = deduplicateLayers(data.tabs.filter(function(t) { return validModuleIds.has(t.moduleId) && !_closedModuleIds.has(t.moduleId); }));
               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);
@@ -1765,8 +1781,8 @@ export function renderExternalAppShell(opts: ExternalAppShellOptions): string {
       })();
       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); });
-      tabBar.addEventListener('layers-close-all', () => { layers = []; tabBar.setLayers([]); tabBar.setAttribute('active', ''); saveTabs(); var dashUrl = window.location.hostname.endsWith('.rspace.online') ? '/' : '/' + spaceSlug; window.location.href = dashUrl; });
+      tabBar.addEventListener('layer-close', (e) => { const { layerId } = e.detail; const closedMid = layerId.replace('layer-', ''); _closedModuleIds.add(closedMid); 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); });
+      tabBar.addEventListener('layers-close-all', () => { layers.forEach(l => _closedModuleIds.add(l.moduleId)); layers = []; tabBar.setLayers([]); tabBar.setAttribute('active', ''); saveTabs(); var dashUrl = window.location.hostname.endsWith('.rspace.online') ? '/' : '/' + spaceSlug; window.location.href = dashUrl; });
       tabBar.addEventListener('layer-reorder', (e) => { const { layerId, newIndex } = e.detail; const oldIdx = layers.findIndex(l => l.id === layerId); if (oldIdx === -1 || oldIdx === newIndex) return; const [moved] = layers.splice(oldIdx, 1); layers.splice(newIndex, 0, moved); layers.forEach((l, i) => l.order = i); saveTabs(); tabBar.setLayers(layers); });
     }
   </script>