diff --git a/src/renderer/components/extensions/plugins/PluginDetailDialog.tsx b/src/renderer/components/extensions/plugins/PluginDetailDialog.tsx
index 9d501e81..74d76b76 100644
--- a/src/renderer/components/extensions/plugins/PluginDetailDialog.tsx
+++ b/src/renderer/components/extensions/plugins/PluginDetailDialog.tsx
@@ -87,6 +87,12 @@ export const PluginDetailDialog = ({
     }
   }, [plugin, open, fetchPluginReadme]);
 
+  useEffect(() => {
+    if (open) {
+      setScope('user');
+    }
+  }, [open, plugin?.pluginId]);
+
   useEffect(() => {
     if (scope === 'project' && !projectScopeAvailable) {
       setScope('user');
diff --git a/src/renderer/components/extensions/plugins/PluginsPanel.tsx b/src/renderer/components/extensions/plugins/PluginsPanel.tsx
index 7584fa74..5480b7c8 100644
--- a/src/renderer/components/extensions/plugins/PluginsPanel.tsx
+++ b/src/renderer/components/extensions/plugins/PluginsPanel.tsx
@@ -148,6 +148,12 @@ export const PluginsPanel = ({
     }
   }, [loading, selectedPlugin, selectedPluginId, setSelectedPluginId]);
 
+  useEffect(() => {
+    if (error && selectedPluginId) {
+      setSelectedPluginId(null);
+    }
+  }, [error, selectedPluginId, setSelectedPluginId]);
+
   const sortValue = `${pluginSort.field}:${pluginSort.order}`;
   const activeFilterCount =
     pluginFilters.categories.length +
diff --git a/src/renderer/store/slices/extensionsSlice.ts b/src/renderer/store/slices/extensionsSlice.ts
index abea1a2f..e18437ff 100644
--- a/src/renderer/store/slices/extensionsSlice.ts
+++ b/src/renderer/store/slices/extensionsSlice.ts
@@ -127,7 +127,8 @@ export interface ExtensionsSlice {
 // Slice Creator
 // =============================================================================
 
-let pluginFetchInFlight: Promise<void> | null = null;
+let pluginFetchInFlight: { key: string; promise: Promise<void> } | null = null;
+let pluginCatalogRequestSeq = 0;
 let mcpDiagnosticsInFlight: Promise<void> | null = null;
 let skillsCatalogRequestSeq = 0;
 let skillsDetailRequestSeq = 0;
@@ -140,6 +141,10 @@ function hasAnyLoading(loadingMap: Record<string, boolean>): boolean {
   return Object.values(loadingMap).some(Boolean);
 }
 
+function getPluginCatalogKey(projectPath?: string): string {
+  return projectPath ?? '__user__';
+}
+
 function getSkillsCatalogKey(projectPath?: string): string {
   return projectPath ?? USER_SKILLS_CATALOG_KEY;
 }
@@ -205,34 +210,52 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
   // ── Plugin catalog fetch ──
   fetchPluginCatalog: async (projectPath?: string, forceRefresh?: boolean) => {
     if (!api.plugins) return;
+    const requestKey = getPluginCatalogKey(projectPath);
 
     // Dedup concurrent requests
-    if (pluginFetchInFlight && !forceRefresh) {
-      await pluginFetchInFlight;
+    if (pluginFetchInFlight && !forceRefresh && pluginFetchInFlight.key === requestKey) {
+      await pluginFetchInFlight.promise;
       return;
     }
 
+    const requestSeq = ++pluginCatalogRequestSeq;
     set({ pluginCatalogLoading: true, pluginCatalogError: null });
 
     const promise = (async () => {
       try {
         const result = await api.plugins!.getAll(projectPath, forceRefresh);
-        set({
-          pluginCatalog: result,
-          pluginCatalogLoading: false,
-          pluginCatalogProjectPath: projectPath ?? null,
+        set(() => {
+          if (requestSeq !== pluginCatalogRequestSeq) {
+            return {};
+          }
+
+          return {
+            pluginCatalog: result,
+            pluginCatalogLoading: false,
+            pluginCatalogError: null,
+            pluginCatalogProjectPath: projectPath ?? null,
+          };
         });
       } catch (err) {
-        set({
-          pluginCatalogLoading: false,
-          pluginCatalogError: err instanceof Error ? err.message : 'Failed to load plugins',
+        set(() => {
+          if (requestSeq !== pluginCatalogRequestSeq) {
+            return {};
+          }
+
+          return {
+            pluginCatalogLoading: false,
+            pluginCatalogError: err instanceof Error ? err.message : 'Failed to load plugins',
+            pluginCatalogProjectPath: projectPath ?? null,
+          };
         });
       } finally {
-        pluginFetchInFlight = null;
+        if (pluginFetchInFlight?.promise === promise) {
+          pluginFetchInFlight = null;
+        }
       }
     })();
 
-    pluginFetchInFlight = promise;
+    pluginFetchInFlight = { key: requestKey, promise };
     await promise;
   },
 
diff --git a/test/renderer/store/extensionsSlice.test.ts b/test/renderer/store/extensionsSlice.test.ts
index 3240c33a..278f61e1 100644
--- a/test/renderer/store/extensionsSlice.test.ts
+++ b/test/renderer/store/extensionsSlice.test.ts
@@ -166,6 +166,61 @@ describe('extensionsSlice', () => {
       expect(store.getState().pluginCatalogError).toBe('boom');
       expect(store.getState().pluginCatalogLoading).toBe(false);
     });
+
+    it('dedups concurrent requests for the same project key', async () => {
+      let resolveFetch!: (plugins: EnrichedPlugin[]) => void;
+      const inFlight = new Promise<EnrichedPlugin[]>((resolve) => {
+        resolveFetch = resolve;
+      });
+      (api.plugins!.getAll as ReturnType<typeof vi.fn>).mockImplementation(() => inFlight);
+
+      const firstFetch = store.getState().fetchPluginCatalog('/tmp/project-a');
+      const secondFetch = store.getState().fetchPluginCatalog('/tmp/project-a');
+
+      expect(api.plugins!.getAll).toHaveBeenCalledTimes(1);
+
+      resolveFetch([makePlugin({ pluginId: 'same@m' })]);
+      await Promise.all([firstFetch, secondFetch]);
+
+      expect(store.getState().pluginCatalogProjectPath).toBe('/tmp/project-a');
+      expect(store.getState().pluginCatalog.map((plugin) => plugin.pluginId)).toEqual(['same@m']);
+    });
+
+    it('keeps the newest project catalog when project changes mid-flight', async () => {
+      let resolveProjectA!: (plugins: EnrichedPlugin[]) => void;
+      let resolveProjectB!: (plugins: EnrichedPlugin[]) => void;
+      const projectAFetch = new Promise<EnrichedPlugin[]>((resolve) => {
+        resolveProjectA = resolve;
+      });
+      const projectBFetch = new Promise<EnrichedPlugin[]>((resolve) => {
+        resolveProjectB = resolve;
+      });
+
+      (api.plugins!.getAll as ReturnType<typeof vi.fn>)
+        .mockImplementationOnce(() => projectAFetch)
+        .mockImplementationOnce(() => projectBFetch);
+
+      const firstFetch = store.getState().fetchPluginCatalog('/tmp/project-a');
+      const secondFetch = store.getState().fetchPluginCatalog('/tmp/project-b');
+
+      expect(api.plugins!.getAll).toHaveBeenCalledTimes(2);
+
+      resolveProjectB([makePlugin({ pluginId: 'project-b@m' })]);
+      await secondFetch;
+
+      expect(store.getState().pluginCatalogProjectPath).toBe('/tmp/project-b');
+      expect(store.getState().pluginCatalog.map((plugin) => plugin.pluginId)).toEqual([
+        'project-b@m',
+      ]);
+
+      resolveProjectA([makePlugin({ pluginId: 'project-a@m' })]);
+      await firstFetch;
+
+      expect(store.getState().pluginCatalogProjectPath).toBe('/tmp/project-b');
+      expect(store.getState().pluginCatalog.map((plugin) => plugin.pluginId)).toEqual([
+        'project-b@m',
+      ]);
+    });
   });
 
   describe('fetchPluginReadme', () => {