diff --git a/server/utils/plugin-loader.js b/server/utils/plugin-loader.js
index 2f961526..9b8cf244 100644
--- a/server/utils/plugin-loader.js
+++ b/server/utils/plugin-loader.js
@@ -31,9 +31,9 @@ export function getPluginsConfig() {
 export function savePluginsConfig(config) {
   const dir = path.dirname(PLUGINS_CONFIG_PATH);
   if (!fs.existsSync(dir)) {
-    fs.mkdirSync(dir, { recursive: true });
+    fs.mkdirSync(dir, { recursive: true, mode: 0o700 });
   }
-  fs.writeFileSync(PLUGINS_CONFIG_PATH, JSON.stringify(config, null, 2));
+  fs.writeFileSync(PLUGINS_CONFIG_PATH, JSON.stringify(config, null, 2), { mode: 0o600 });
 }
 
 export function validateManifest(manifest) {
@@ -60,6 +60,23 @@ export function validateManifest(manifest) {
     return { valid: false, error: `Invalid plugin slot: ${manifest.slot}. Must be one of: ${ALLOWED_SLOTS.join(', ')}` };
   }
 
+  // Validate entry is a relative path without traversal
+  if (manifest.entry.includes('..') || path.isAbsolute(manifest.entry)) {
+    return { valid: false, error: 'Entry must be a relative path without ".."' };
+  }
+
+  if (manifest.server !== undefined && manifest.server !== null) {
+    if (typeof manifest.server !== 'string' || manifest.server.includes('..') || path.isAbsolute(manifest.server)) {
+      return { valid: false, error: 'Server entry must be a relative path string without ".."' };
+    }
+  }
+
+  if (manifest.permissions !== undefined) {
+    if (!Array.isArray(manifest.permissions) || !manifest.permissions.every(p => typeof p === 'string')) {
+      return { valid: false, error: 'Permissions must be an array of strings' };
+    }
+  }
+
   return { valid: true };
 }
 
@@ -235,6 +252,13 @@ export function installPluginFromGit(url) {
         return reject(new Error(`Invalid manifest: ${validation.error}`));
       }
 
+      // Reject if another installed plugin already uses this name
+      const existing = scanPlugins().find(p => p.name === manifest.name);
+      if (existing) {
+        cleanupTemp();
+        return reject(new Error(`A plugin named "${manifest.name}" is already installed (in "${existing.dirName}")`));
+      }
+
       // Run npm install if package.json exists.
       // --ignore-scripts prevents postinstall hooks from executing arbitrary code.
       const packageJsonPath = path.join(tempDir, 'package.json');
diff --git a/src/components/plugins/PluginSettingsTab.tsx b/src/components/plugins/PluginSettingsTab.tsx
index 65aafe17..28d4df0b 100644
--- a/src/components/plugins/PluginSettingsTab.tsx
+++ b/src/components/plugins/PluginSettingsTab.tsx
@@ -7,7 +7,7 @@ import PluginIcon from './PluginIcon';
 const STARTER_PLUGIN_URL = 'https://github.com/cloudcli-ai/cloudcli-plugin-starter';
 
 /* ─── Toggle Switch ─────────────────────────────────────────────────────── */
-function ToggleSwitch({ checked, onChange }: { checked: boolean; onChange: (v: boolean) => void }) {
+function ToggleSwitch({ checked, onChange, ariaLabel }: { checked: boolean; onChange: (v: boolean) => void; ariaLabel: string }) {
   return (
     <label className="relative inline-flex cursor-pointer select-none items-center">
       <input
@@ -15,6 +15,7 @@ function ToggleSwitch({ checked, onChange }: { checked: boolean; onChange: (v: b
         className="peer sr-only"
         checked={checked}
         onChange={(e) => onChange(e.target.checked)}
+        aria-label={ariaLabel}
       />
       <div
         className={`
@@ -141,8 +142,9 @@ function PluginCard({
           <div className="flex flex-shrink-0 items-center gap-2">
             <button
               onClick={onUpdate}
-              disabled={updating}
-              title="Pull latest from git"
+              disabled={updating || !plugin.repoUrl}
+              title={plugin.repoUrl ? 'Pull latest from git' : 'No git remote — update not available'}
+              aria-label={`Update ${plugin.displayName}`}
               className="rounded p-1.5 text-muted-foreground transition-colors hover:bg-muted hover:text-foreground disabled:opacity-40"
             >
               {updating ? (
@@ -155,6 +157,7 @@ function PluginCard({
             <button
               onClick={onUninstall}
               title={confirmingUninstall ? 'Click again to confirm' : 'Uninstall plugin'}
+              aria-label={`Uninstall ${plugin.displayName}`}
               className={`rounded p-1.5 transition-colors ${
                 confirmingUninstall
                   ? 'bg-red-50 text-red-500 hover:bg-red-100 dark:bg-red-900/20 dark:hover:bg-red-900/30'
@@ -164,7 +167,7 @@ function PluginCard({
               <Trash2 className="h-3.5 w-3.5" />
             </button>
 
-            <ToggleSwitch checked={plugin.enabled} onChange={onToggle} />
+            <ToggleSwitch checked={plugin.enabled} onChange={onToggle} ariaLabel={`${plugin.enabled ? 'Disable' : 'Enable'} ${plugin.displayName}`} />
           </div>
         </div>
 
@@ -268,17 +271,17 @@ export default function PluginSettingsTab() {
   const [installingStarter, setInstallingStarter] = useState(false);
   const [installError, setInstallError] = useState<string | null>(null);
   const [confirmUninstall, setConfirmUninstall] = useState<string | null>(null);
-  const [updatingPlugin, setUpdatingPlugin] = useState<string | null>(null);
+  const [updatingPlugins, setUpdatingPlugins] = useState<Set<string>>(new Set());
   const [updateErrors, setUpdateErrors] = useState<Record<string, string>>({});
 
   const handleUpdate = async (name: string) => {
-    setUpdatingPlugin(name);
+    setUpdatingPlugins((prev) => new Set(prev).add(name));
     setUpdateErrors((prev) => { const next = { ...prev }; delete next[name]; return next; });
     const result = await updatePlugin(name);
     if (!result.success) {
       setUpdateErrors((prev) => ({ ...prev, [name]: result.error || 'Update failed' }));
     }
-    setUpdatingPlugin(null);
+    setUpdatingPlugins((prev) => { const next = new Set(prev); next.delete(name); return next; });
   };
 
   const handleInstall = async () => {
@@ -399,7 +402,7 @@ export default function PluginSettingsTab() {
               onToggle={(enabled) => void togglePlugin(plugin.name, enabled)}
               onUpdate={() => void handleUpdate(plugin.name)}
               onUninstall={() => void handleUninstall(plugin.name)}
-              updating={updatingPlugin === plugin.name}
+              updating={updatingPlugins.has(plugin.name)}
               confirmingUninstall={confirmUninstall === plugin.name}
               onCancelUninstall={() => setConfirmUninstall(null)}
               updateError={updateErrors[plugin.name] ?? null}
diff --git a/src/components/plugins/PluginTabContent.tsx b/src/components/plugins/PluginTabContent.tsx
index fb4afc45..a9be3bcf 100644
--- a/src/components/plugins/PluginTabContent.tsx
+++ b/src/components/plugins/PluginTabContent.tsx
@@ -105,6 +105,11 @@ export default function PluginTabContent({
         };
 
         await mod.mount?.(container, api);
+        if (!active) {
+          try { mod.unmount?.(container); } catch { /* ignore */ }
+          moduleRef.current = null;
+          return;
+        }
       } catch (err) {
         if (!active) return;
         console.error(`[Plugin:${pluginName}] Failed to load:`, err);