diff --git a/src/renderer/components/extensions/mcp/McpServerDetailDialog.tsx b/src/renderer/components/extensions/mcp/McpServerDetailDialog.tsx
index c6515f8d..87ef0a08 100644
--- a/src/renderer/components/extensions/mcp/McpServerDetailDialog.tsx
+++ b/src/renderer/components/extensions/mcp/McpServerDetailDialog.tsx
@@ -76,7 +76,7 @@ export const McpServerDetailDialog = ({
   const cliStatus = useStore((s) => s.cliStatus);
   const defaultSharedScope = getDefaultMcpSharedScope(cliStatus?.flavor);
   const [scope, setScope] = useState<Scope>(defaultSharedScope);
-  const operationKey = server ? getMcpOperationKey(server.id, scope) : null;
+  const operationKey = server ? getMcpOperationKey(server.id, scope, projectPath) : null;
   const installProgress = useStore(
     (s) => (operationKey ? s.mcpInstallProgress[operationKey] : undefined) ?? 'idle'
   );
diff --git a/src/renderer/components/extensions/mcp/McpServersPanel.tsx b/src/renderer/components/extensions/mcp/McpServersPanel.tsx
index c799433a..816ba2b0 100644
--- a/src/renderer/components/extensions/mcp/McpServersPanel.tsx
+++ b/src/renderer/components/extensions/mcp/McpServersPanel.tsx
@@ -18,6 +18,7 @@ import { formatRelativeTime } from '@renderer/utils/formatters';
 import { CLI_NOT_FOUND_MARKER } from '@shared/constants/cli';
 import {
   getMcpDiagnosticKey,
+  getMcpProjectStateKey,
   getPreferredMcpInstallationEntry,
   sanitizeMcpServerName,
 } from '@shared/utils/extensionNormalizers';
@@ -79,18 +80,24 @@ export const McpServersPanel = ({
   selectedMcpServerId,
   setSelectedMcpServerId,
 }: McpServersPanelProps): React.JSX.Element => {
+  const projectStateKey = getMcpProjectStateKey(projectPath);
   const {
     browseCatalog,
     browseNextCursor,
     browseLoading,
     browseError,
     mcpBrowse,
-    installedServers,
+    installedServersByProjectPath,
+    installedServersFallback,
     fetchMcpGitHubStars,
-    mcpDiagnostics,
-    mcpDiagnosticsLoading,
-    mcpDiagnosticsError,
-    mcpDiagnosticsLastCheckedAt,
+    mcpDiagnosticsByProjectPath,
+    mcpDiagnosticsFallback,
+    mcpDiagnosticsLoadingByProjectPath,
+    mcpDiagnosticsLoadingFallback,
+    mcpDiagnosticsErrorByProjectPath,
+    mcpDiagnosticsErrorFallback,
+    mcpDiagnosticsLastCheckedAtByProjectPath,
+    mcpDiagnosticsLastCheckedAtFallback,
     runMcpDiagnostics,
     cliStatus,
   } = useStore(
@@ -100,16 +107,33 @@ export const McpServersPanel = ({
       browseLoading: s.mcpBrowseLoading,
       browseError: s.mcpBrowseError,
       mcpBrowse: s.mcpBrowse,
-      installedServers: s.mcpInstalledServers,
+      installedServersByProjectPath: s.mcpInstalledServersByProjectPath,
+      installedServersFallback: s.mcpInstalledServers,
       fetchMcpGitHubStars: s.fetchMcpGitHubStars,
-      mcpDiagnostics: s.mcpDiagnostics,
-      mcpDiagnosticsLoading: s.mcpDiagnosticsLoading,
-      mcpDiagnosticsError: s.mcpDiagnosticsError,
-      mcpDiagnosticsLastCheckedAt: s.mcpDiagnosticsLastCheckedAt,
+      mcpDiagnosticsByProjectPath: s.mcpDiagnosticsByProjectPath,
+      mcpDiagnosticsFallback: s.mcpDiagnostics,
+      mcpDiagnosticsLoadingByProjectPath: s.mcpDiagnosticsLoadingByProjectPath,
+      mcpDiagnosticsLoadingFallback: s.mcpDiagnosticsLoading,
+      mcpDiagnosticsErrorByProjectPath: s.mcpDiagnosticsErrorByProjectPath,
+      mcpDiagnosticsErrorFallback: s.mcpDiagnosticsError,
+      mcpDiagnosticsLastCheckedAtByProjectPath: s.mcpDiagnosticsLastCheckedAtByProjectPath,
+      mcpDiagnosticsLastCheckedAtFallback: s.mcpDiagnosticsLastCheckedAt,
       runMcpDiagnostics: s.runMcpDiagnostics,
       cliStatus: s.cliStatus,
     }))
   );
+  const installedServers =
+    installedServersByProjectPath?.[projectStateKey] ?? installedServersFallback ?? [];
+  const mcpDiagnostics =
+    mcpDiagnosticsByProjectPath?.[projectStateKey] ?? mcpDiagnosticsFallback ?? {};
+  const mcpDiagnosticsLoading =
+    mcpDiagnosticsLoadingByProjectPath?.[projectStateKey] ?? mcpDiagnosticsLoadingFallback ?? false;
+  const mcpDiagnosticsError =
+    mcpDiagnosticsErrorByProjectPath?.[projectStateKey] ?? mcpDiagnosticsErrorFallback ?? null;
+  const mcpDiagnosticsLastCheckedAt =
+    mcpDiagnosticsLastCheckedAtByProjectPath?.[projectStateKey] ??
+    mcpDiagnosticsLastCheckedAtFallback ??
+    null;
 
   const [mcpSort, setMcpSort] = useState<McpSortValue>('name-asc');
 
diff --git a/src/renderer/store/slices/extensionsSlice.ts b/src/renderer/store/slices/extensionsSlice.ts
index 15fb4556..20dbae3b 100644
--- a/src/renderer/store/slices/extensionsSlice.ts
+++ b/src/renderer/store/slices/extensionsSlice.ts
@@ -8,6 +8,7 @@ import { CLI_NOT_FOUND_MESSAGE } from '@shared/constants/cli';
 import { isProjectScopedMcpScope } from '@shared/utils/mcpScopes';
 import {
   getMcpDiagnosticKey,
+  getMcpProjectStateKey,
   getMcpOperationKey,
   getPluginOperationKey,
 } from '@shared/utils/extensionNormalizers';
@@ -56,11 +57,16 @@ export interface ExtensionsSlice {
   mcpBrowseLoading: boolean;
   mcpBrowseError: string | null;
   mcpInstalledServers: InstalledMcpEntry[];
+  mcpInstalledServersByProjectPath: Record<string, InstalledMcpEntry[]>;
   mcpInstalledProjectPath: string | null;
   mcpDiagnostics: Record<string, McpServerDiagnostic>;
+  mcpDiagnosticsByProjectPath: Record<string, Record<string, McpServerDiagnostic>>;
   mcpDiagnosticsLoading: boolean;
+  mcpDiagnosticsLoadingByProjectPath: Record<string, boolean>;
   mcpDiagnosticsError: string | null;
+  mcpDiagnosticsErrorByProjectPath: Record<string, string | null>;
   mcpDiagnosticsLastCheckedAt: number | null;
+  mcpDiagnosticsLastCheckedAtByProjectPath: Record<string, number | null>;
 
   // ── Install progress ──
   pluginInstallProgress: Record<string, ExtensionOperationState>;
@@ -137,7 +143,7 @@ let pluginFetchInFlight: { key: string; promise: Promise<void> } | null = null;
 let pluginCatalogRequestSeq = 0;
 const pluginSuccessResetTimers = new Map<string, ReturnType<typeof setTimeout>>();
 const mcpSuccessResetTimers = new Map<string, ReturnType<typeof setTimeout>>();
-let mcpDiagnosticsInFlight: Promise<void> | null = null;
+const mcpDiagnosticsInFlightByKey = new Map<string, Promise<void>>();
 let skillsCatalogRequestSeq = 0;
 let skillsDetailRequestSeq = 0;
 const latestSkillsCatalogRequestByKey = new Map<string, number>();
@@ -227,10 +233,26 @@ function schedulePluginSuccessReset(
   pluginSuccessResetTimers.set(operationKey, timer);
 }
 
-function getCustomMcpOperationKey(serverName: string, scope: InstallScope): string {
+function getCustomMcpOperationKey(
+  serverName: string,
+  scope: InstallScope,
+  projectPath?: string | null
+): string {
+  if (scope === 'project' || scope === 'local') {
+    return `mcp-custom:${serverName}:${scope}:${getMcpProjectStateKey(projectPath)}`;
+  }
   return `mcp-custom:${serverName}:${scope}`;
 }
 
+function isProjectScopedMcpOperationKey(operationKey: string): boolean {
+  return (
+    operationKey.includes(':project:') ||
+    operationKey.endsWith(':project') ||
+    operationKey.includes(':local:') ||
+    operationKey.endsWith(':local')
+  );
+}
+
 function clearMcpSuccessResetTimer(operationKey: string): void {
   const timer = mcpSuccessResetTimers.get(operationKey);
   if (!timer) {
@@ -274,7 +296,7 @@ function clearMcpProjectScopedOperationState(
   for (const operationKey of Object.keys(nextMcpInstallProgress)) {
     if (
       (operationKey.startsWith('mcp:') || operationKey.startsWith('mcp-custom:')) &&
-      (operationKey.endsWith(':project') || operationKey.endsWith(':local'))
+      isProjectScopedMcpOperationKey(operationKey)
     ) {
       delete nextMcpInstallProgress[operationKey];
     }
@@ -283,7 +305,7 @@ function clearMcpProjectScopedOperationState(
   for (const operationKey of Object.keys(nextInstallErrors)) {
     if (
       (operationKey.startsWith('mcp:') || operationKey.startsWith('mcp-custom:')) &&
-      (operationKey.endsWith(':project') || operationKey.endsWith(':local'))
+      isProjectScopedMcpOperationKey(operationKey)
     ) {
       delete nextInstallErrors[operationKey];
     }
@@ -297,7 +319,7 @@ function clearMcpProjectScopedOperationState(
 
 function clearMcpProjectScopedSuccessResetTimers(): void {
   for (const operationKey of Array.from(mcpSuccessResetTimers.keys())) {
-    if (operationKey.endsWith(':project') || operationKey.endsWith(':local')) {
+    if (isProjectScopedMcpOperationKey(operationKey)) {
       clearMcpSuccessResetTimer(operationKey);
     }
   }
@@ -336,11 +358,16 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
   mcpBrowseLoading: false,
   mcpBrowseError: null,
   mcpInstalledServers: [],
+  mcpInstalledServersByProjectPath: {},
   mcpInstalledProjectPath: null,
   mcpDiagnostics: {},
+  mcpDiagnosticsByProjectPath: {},
   mcpDiagnosticsLoading: false,
+  mcpDiagnosticsLoadingByProjectPath: {},
   mcpDiagnosticsError: null,
+  mcpDiagnosticsErrorByProjectPath: {},
   mcpDiagnosticsLastCheckedAt: null,
+  mcpDiagnosticsLastCheckedAtByProjectPath: {},
 
   pluginInstallProgress: {},
   mcpInstallProgress: {},
@@ -519,6 +546,7 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
       const installed = await api.mcpRegistry.getInstalled(projectPath);
       set((prev) => {
         const nextProjectPath = projectPath ?? null;
+        const stateKey = getMcpProjectStateKey(nextProjectPath);
         const isSameProjectContext = prev.mcpInstalledProjectPath === nextProjectPath;
         const nextOperationState = isSameProjectContext
           ? {
@@ -533,6 +561,10 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
 
         return {
           mcpInstalledServers: installed,
+          mcpInstalledServersByProjectPath: {
+            ...prev.mcpInstalledServersByProjectPath,
+            [stateKey]: installed,
+          },
           mcpInstalledProjectPath: nextProjectPath,
           mcpInstallProgress: nextOperationState.mcpInstallProgress,
           installErrors: nextOperationState.installErrors,
@@ -546,38 +578,72 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
   runMcpDiagnostics: async (projectPath?: string) => {
     const mcpRegistry = api.mcpRegistry;
     if (!mcpRegistry) return;
+    const projectStateKey = getMcpProjectStateKey(projectPath);
 
-    if (mcpDiagnosticsInFlight) {
-      await mcpDiagnosticsInFlight;
+    const existing = mcpDiagnosticsInFlightByKey.get(projectStateKey);
+    if (existing) {
+      await existing;
       return;
     }
 
-    set({ mcpDiagnosticsLoading: true, mcpDiagnosticsError: null });
+    set((prev) => ({
+      mcpDiagnosticsLoading: true,
+      mcpDiagnosticsError: null,
+      mcpDiagnosticsLoadingByProjectPath: {
+        ...prev.mcpDiagnosticsLoadingByProjectPath,
+        [projectStateKey]: true,
+      },
+      mcpDiagnosticsErrorByProjectPath: {
+        ...prev.mcpDiagnosticsErrorByProjectPath,
+        [projectStateKey]: null,
+      },
+    }));
 
     const promise = (async () => {
       try {
         const diagnostics = await mcpRegistry.diagnose(projectPath);
+        const diagnosticsRecord = Object.fromEntries(
+          diagnostics.map((entry) => [getMcpDiagnosticKey(entry.name, entry.scope), entry] as const)
+        );
+        const checkedAt = Date.now();
         set({
-          mcpDiagnostics: Object.fromEntries(
-            diagnostics.map(
-              (entry) => [getMcpDiagnosticKey(entry.name, entry.scope), entry] as const
-            )
-          ),
+          mcpDiagnostics: diagnosticsRecord,
           mcpDiagnosticsLoading: false,
-          mcpDiagnosticsLastCheckedAt: Date.now(),
+          mcpDiagnosticsByProjectPath: {
+            ...get().mcpDiagnosticsByProjectPath,
+            [projectStateKey]: diagnosticsRecord,
+          },
+          mcpDiagnosticsLoadingByProjectPath: {
+            ...get().mcpDiagnosticsLoadingByProjectPath,
+            [projectStateKey]: false,
+          },
+          mcpDiagnosticsLastCheckedAt: checkedAt,
+          mcpDiagnosticsLastCheckedAtByProjectPath: {
+            ...get().mcpDiagnosticsLastCheckedAtByProjectPath,
+            [projectStateKey]: checkedAt,
+          },
         });
       } catch (err) {
+        const errorMessage =
+          err instanceof Error ? err.message : 'Failed to check MCP server health';
         set({
           mcpDiagnosticsLoading: false,
-          mcpDiagnosticsError:
-            err instanceof Error ? err.message : 'Failed to check MCP server health',
+          mcpDiagnosticsError: errorMessage,
+          mcpDiagnosticsLoadingByProjectPath: {
+            ...get().mcpDiagnosticsLoadingByProjectPath,
+            [projectStateKey]: false,
+          },
+          mcpDiagnosticsErrorByProjectPath: {
+            ...get().mcpDiagnosticsErrorByProjectPath,
+            [projectStateKey]: errorMessage,
+          },
         });
       } finally {
-        mcpDiagnosticsInFlight = null;
+        mcpDiagnosticsInFlightByKey.delete(projectStateKey);
       }
     })();
 
-    mcpDiagnosticsInFlight = promise;
+    mcpDiagnosticsInFlightByKey.set(projectStateKey, promise);
     await promise;
   },
 
@@ -935,7 +1001,7 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
 
   // ── MCP install ──
   installMcpServer: async (request: McpInstallRequest) => {
-    const operationKey = getMcpOperationKey(request.registryId, request.scope);
+    const operationKey = getMcpOperationKey(request.registryId, request.scope, request.projectPath);
     if (!api.mcpRegistry) {
       clearMcpSuccessResetTimer(operationKey);
       set((prev) => ({
@@ -967,8 +1033,8 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
       }
 
       await Promise.all([
-        get().mcpFetchInstalled(get().mcpInstalledProjectPath ?? undefined),
-        get().runMcpDiagnostics(get().mcpInstalledProjectPath ?? undefined),
+        get().mcpFetchInstalled(request.projectPath),
+        get().runMcpDiagnostics(request.projectPath),
       ]);
 
       set((prev) => ({
@@ -989,7 +1055,11 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
   // ── MCP custom install ──
   installCustomMcpServer: async (request: McpCustomInstallRequest) => {
     const operationScope = request.scope;
-    const progressKey = getCustomMcpOperationKey(request.serverName, operationScope);
+    const progressKey = getCustomMcpOperationKey(
+      request.serverName,
+      operationScope,
+      request.projectPath
+    );
     if (!api.mcpRegistry) {
       clearMcpSuccessResetTimer(progressKey);
       set((prev) => ({
@@ -1015,8 +1085,8 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
       }
 
       await Promise.all([
-        get().mcpFetchInstalled(get().mcpInstalledProjectPath ?? undefined),
-        get().runMcpDiagnostics(get().mcpInstalledProjectPath ?? undefined),
+        get().mcpFetchInstalled(request.projectPath),
+        get().runMcpDiagnostics(request.projectPath),
       ]);
 
       set((prev) => ({
@@ -1043,7 +1113,7 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
   ) => {
     const operationScope: InstallScope =
       scope === 'global' || scope === 'user' || isProjectScopedMcpScope(scope) ? scope : 'user';
-    const operationKey = getMcpOperationKey(registryId, operationScope);
+    const operationKey = getMcpOperationKey(registryId, operationScope, projectPath);
     if (!api.mcpRegistry) {
       clearMcpSuccessResetTimer(operationKey);
       set((prev) => ({
@@ -1072,8 +1142,8 @@ export const createExtensionsSlice: StateCreator<AppState, [], [], ExtensionsSli
       }
 
       await Promise.all([
-        get().mcpFetchInstalled(get().mcpInstalledProjectPath ?? undefined),
-        get().runMcpDiagnostics(get().mcpInstalledProjectPath ?? undefined),
+        get().mcpFetchInstalled(projectPath),
+        get().runMcpDiagnostics(projectPath),
       ]);
 
       set((prev) => ({
diff --git a/src/shared/utils/extensionNormalizers.ts b/src/shared/utils/extensionNormalizers.ts
index 5601f944..356946bf 100644
--- a/src/shared/utils/extensionNormalizers.ts
+++ b/src/shared/utils/extensionNormalizers.ts
@@ -116,7 +116,14 @@ export function getPluginOperationKey(pluginId: string, scope: InstallScope): st
 /**
  * Namespaced operation-state key for MCP install/uninstall UI state.
  */
-export function getMcpOperationKey(registryId: string, scope: InstallScope): string {
+export function getMcpOperationKey(
+  registryId: string,
+  scope: InstallScope,
+  projectPath?: string | null
+): string {
+  if (scope === 'project' || scope === 'local') {
+    return `mcp:${registryId}:${scope}:${getMcpProjectStateKey(projectPath)}`;
+  }
   return `mcp:${registryId}:${scope}`;
 }
 
@@ -128,6 +135,13 @@ export function getMcpDiagnosticKey(name: string, scope?: string | null): string
   return scope ? `mcp-diagnostic:${scope}:${name}` : `mcp-diagnostic:${name}`;
 }
 
+/**
+ * Stable project-aware cache key for MCP installed/diagnostics state.
+ */
+export function getMcpProjectStateKey(projectPath?: string | null): string {
+  return projectPath ?? '__global__';
+}
+
 /**
  * Check whether a plugin has an installation for the selected scope.
  */
diff --git a/test/renderer/components/extensions/mcp/McpServerCard.test.ts b/test/renderer/components/extensions/mcp/McpServerCard.test.ts
index 85ccf6d5..db2adef6 100644
--- a/test/renderer/components/extensions/mcp/McpServerCard.test.ts
+++ b/test/renderer/components/extensions/mcp/McpServerCard.test.ts
@@ -255,11 +255,12 @@ describe('McpServerCard direct action safety', () => {
     };
 
     storeState.mcpInstallProgress = {
-      [getMcpOperationKey('io.github.upstash/context7', 'project')]: 'error',
+      [getMcpOperationKey('io.github.upstash/context7', 'project', '/tmp/project')]: 'error',
       [getMcpOperationKey('io.github.upstash/context7', 'user')]: 'pending',
     };
     storeState.installErrors = {
-      [getMcpOperationKey('io.github.upstash/context7', 'project')]: 'Project failed',
+      [getMcpOperationKey('io.github.upstash/context7', 'project', '/tmp/project')]:
+        'Project failed',
       [getMcpOperationKey('io.github.upstash/context7', 'user')]: 'User failed',
     };
 
diff --git a/test/renderer/components/extensions/mcp/McpServerDetailDialog.test.ts b/test/renderer/components/extensions/mcp/McpServerDetailDialog.test.ts
index a5e9ea00..7e1b32e9 100644
--- a/test/renderer/components/extensions/mcp/McpServerDetailDialog.test.ts
+++ b/test/renderer/components/extensions/mcp/McpServerDetailDialog.test.ts
@@ -581,10 +581,11 @@ describe('McpServerDetailDialog installed entry handling', () => {
     const root = createRoot(host);
     storeState.mcpInstallProgress = {
       [getMcpOperationKey('io.github.upstash/context7', 'user')]: 'success',
-      [getMcpOperationKey('io.github.upstash/context7', 'project')]: 'error',
+      [getMcpOperationKey('io.github.upstash/context7', 'project', '/tmp/project')]: 'error',
     };
     storeState.installErrors = {
-      [getMcpOperationKey('io.github.upstash/context7', 'project')]: 'Project failed',
+      [getMcpOperationKey('io.github.upstash/context7', 'project', '/tmp/project')]:
+        'Project failed',
     };
 
     await act(async () => {
diff --git a/test/renderer/components/extensions/mcp/McpServersPanel.test.ts b/test/renderer/components/extensions/mcp/McpServersPanel.test.ts
index 0d9451df..85a2281d 100644
--- a/test/renderer/components/extensions/mcp/McpServersPanel.test.ts
+++ b/test/renderer/components/extensions/mcp/McpServersPanel.test.ts
@@ -18,11 +18,19 @@ interface StoreState {
   mcpBrowseError: string | null;
   mcpBrowse: ReturnType<typeof vi.fn>;
   mcpInstalledServers: Array<{ name: string; scope: 'local' | 'user' | 'project' }>;
+  mcpInstalledServersByProjectPath?: Record<
+    string,
+    Array<{ name: string; scope: 'local' | 'user' | 'project' }>
+  >;
   fetchMcpGitHubStars: ReturnType<typeof vi.fn>;
   mcpDiagnostics: Record<string, never>;
+  mcpDiagnosticsByProjectPath?: Record<string, Record<string, never>>;
   mcpDiagnosticsLoading: boolean;
+  mcpDiagnosticsLoadingByProjectPath?: Record<string, boolean>;
   mcpDiagnosticsError: string | null;
+  mcpDiagnosticsErrorByProjectPath?: Record<string, string | null>;
   mcpDiagnosticsLastCheckedAt: number | null;
+  mcpDiagnosticsLastCheckedAtByProjectPath?: Record<string, number | null>;
   runMcpDiagnostics: ReturnType<typeof vi.fn>;
 }
 
@@ -121,11 +129,16 @@ describe('McpServersPanel initial browse loading', () => {
     storeState.mcpBrowseError = null;
     storeState.mcpBrowse = vi.fn();
     storeState.mcpInstalledServers = [];
+    storeState.mcpInstalledServersByProjectPath = undefined;
     storeState.fetchMcpGitHubStars = vi.fn();
     storeState.mcpDiagnostics = {};
+    storeState.mcpDiagnosticsByProjectPath = undefined;
     storeState.mcpDiagnosticsLoading = false;
+    storeState.mcpDiagnosticsLoadingByProjectPath = undefined;
     storeState.mcpDiagnosticsError = null;
+    storeState.mcpDiagnosticsErrorByProjectPath = undefined;
     storeState.mcpDiagnosticsLastCheckedAt = null;
+    storeState.mcpDiagnosticsLastCheckedAtByProjectPath = undefined;
     storeState.runMcpDiagnostics = vi.fn();
   });
 
diff --git a/test/renderer/store/extensionsSlice.test.ts b/test/renderer/store/extensionsSlice.test.ts
index c9a5337c..350e074c 100644
--- a/test/renderer/store/extensionsSlice.test.ts
+++ b/test/renderer/store/extensionsSlice.test.ts
@@ -56,6 +56,7 @@ vi.mock('../../../src/renderer/api', () => ({
 import { api } from '../../../src/renderer/api';
 import {
   getMcpDiagnosticKey,
+  getMcpProjectStateKey,
   getMcpOperationKey,
   getPluginOperationKey,
 } from '../../../src/shared/utils/extensionNormalizers';
@@ -154,8 +155,11 @@ const makeReadyCliStatus = () => ({
 
 const pluginOperationKey = (pluginId: string, scope: 'user' | 'project' | 'local' = 'user') =>
   getPluginOperationKey(pluginId, scope);
-const mcpOperationKey = (registryId: string, scope: 'user' | 'project' | 'local' = 'user') =>
-  getMcpOperationKey(registryId, scope);
+const mcpOperationKey = (
+  registryId: string,
+  scope: 'user' | 'project' | 'local' | 'global' = 'user',
+  projectPath?: string
+) => getMcpOperationKey(registryId, scope, projectPath);
 
 describe('extensionsSlice', () => {
   let store: TestStore;
@@ -393,20 +397,34 @@ describe('extensionsSlice', () => {
       expect(store.getState().mcpInstalledServers).toEqual(installed);
     });
 
+    it('stores installed MCP servers independently per project context', async () => {
+      (api.mcpRegistry!.getInstalled as ReturnType<typeof vi.fn>)
+        .mockResolvedValueOnce([{ name: 'global-server', scope: 'global' as const }])
+        .mockResolvedValueOnce([{ name: 'project-server', scope: 'project' as const }]);
+
+      await store.getState().mcpFetchInstalled();
+      await store.getState().mcpFetchInstalled('/tmp/project-a');
+
+      expect(store.getState().mcpInstalledServersByProjectPath).toMatchObject({
+        [getMcpProjectStateKey()]: [{ name: 'global-server', scope: 'global' }],
+        [getMcpProjectStateKey('/tmp/project-a')]: [{ name: 'project-server', scope: 'project' }],
+      });
+    });
+
     it('clears stale project- and local-scoped MCP operation state when project changes', async () => {
       store.setState({
         mcpInstalledProjectPath: '/tmp/project-a',
         mcpInstallProgress: {
-          [mcpOperationKey('project-server', 'project')]: 'error',
-          [mcpOperationKey('local-server', 'local')]: 'success',
+          [mcpOperationKey('project-server', 'project', '/tmp/project-a')]: 'error',
+          [mcpOperationKey('local-server', 'local', '/tmp/project-a')]: 'success',
           [mcpOperationKey('user-server', 'user')]: 'pending',
         },
         installErrors: {
-          [mcpOperationKey('project-server', 'project')]: 'Project failed',
-          [mcpOperationKey('local-server', 'local')]: 'Local failed',
+          [mcpOperationKey('project-server', 'project', '/tmp/project-a')]: 'Project failed',
+          [mcpOperationKey('local-server', 'local', '/tmp/project-a')]: 'Local failed',
           [mcpOperationKey('user-server', 'user')]: 'Keep user state',
           'plugin:test@marketplace:user': 'Keep plugin state',
-          'mcp-custom:custom-server:project': 'Clear custom project state',
+          'mcp-custom:custom-server:project:/tmp/project-a': 'Clear custom project state',
         },
       });
       (api.mcpRegistry!.getInstalled as ReturnType<typeof vi.fn>).mockResolvedValue([]);
@@ -414,13 +432,21 @@ describe('extensionsSlice', () => {
       await store.getState().mcpFetchInstalled('/tmp/project-b');
 
       expect(store.getState().mcpInstalledProjectPath).toBe('/tmp/project-b');
-      expect(store.getState().mcpInstallProgress[mcpOperationKey('project-server', 'project')]).toBeUndefined();
-      expect(store.getState().mcpInstallProgress[mcpOperationKey('local-server', 'local')]).toBeUndefined();
+      expect(
+        store.getState().mcpInstallProgress[mcpOperationKey('project-server', 'project', '/tmp/project-a')]
+      ).toBeUndefined();
+      expect(
+        store.getState().mcpInstallProgress[mcpOperationKey('local-server', 'local', '/tmp/project-a')]
+      ).toBeUndefined();
       expect(store.getState().mcpInstallProgress[mcpOperationKey('user-server', 'user')]).toBe(
         'pending',
       );
-      expect(store.getState().installErrors[mcpOperationKey('project-server', 'project')]).toBeUndefined();
-      expect(store.getState().installErrors[mcpOperationKey('local-server', 'local')]).toBeUndefined();
+      expect(
+        store.getState().installErrors[mcpOperationKey('project-server', 'project', '/tmp/project-a')]
+      ).toBeUndefined();
+      expect(
+        store.getState().installErrors[mcpOperationKey('local-server', 'local', '/tmp/project-a')]
+      ).toBeUndefined();
       expect(store.getState().installErrors[mcpOperationKey('user-server', 'user')]).toBe(
         'Keep user state',
       );
@@ -749,16 +775,20 @@ describe('extensionsSlice', () => {
         headers: [],
       });
 
-      expect(store.getState().mcpInstallProgress[mcpOperationKey('test-id', 'project')]).toBe(
-        'success',
-      );
+      expect(
+        store.getState().mcpInstallProgress[mcpOperationKey('test-id', 'project', '/tmp/project-a')]
+      ).toBe('success');
 
       await store.getState().mcpFetchInstalled('/tmp/project-b');
-      expect(store.getState().mcpInstallProgress[mcpOperationKey('test-id', 'project')]).toBeUndefined();
+      expect(
+        store.getState().mcpInstallProgress[mcpOperationKey('test-id', 'project', '/tmp/project-a')]
+      ).toBeUndefined();
 
       await vi.advanceTimersByTimeAsync(2_000);
 
-      expect(store.getState().mcpInstallProgress[mcpOperationKey('test-id', 'project')]).toBeUndefined();
+      expect(
+        store.getState().mcpInstallProgress[mcpOperationKey('test-id', 'project', '/tmp/project-a')]
+      ).toBeUndefined();
     });
   });
 
@@ -868,6 +898,69 @@ describe('extensionsSlice', () => {
         }),
       });
     });
+
+    it('stores MCP diagnostics independently per project context', async () => {
+      (api.mcpRegistry!.diagnose as ReturnType<typeof vi.fn>)
+        .mockResolvedValueOnce([
+          {
+            name: 'global-server',
+            scope: 'global',
+            target: 'npx global-server',
+            status: 'connected',
+            statusLabel: 'Connected',
+            rawLine: 'global-server: npx global-server - Connected',
+            checkedAt: 1,
+          },
+        ])
+        .mockResolvedValueOnce([
+          {
+            name: 'project-server',
+            scope: 'project',
+            target: 'uvx project-server',
+            status: 'failed',
+            statusLabel: 'Failed to connect',
+            rawLine: 'project-server: uvx project-server - Failed to connect',
+            checkedAt: 2,
+          },
+        ]);
+
+      await store.getState().runMcpDiagnostics();
+      await store.getState().runMcpDiagnostics('/tmp/project-a');
+
+      expect(store.getState().mcpDiagnosticsByProjectPath).toMatchObject({
+        [getMcpProjectStateKey()]: {
+          [getMcpDiagnosticKey('global-server', 'global')]: expect.objectContaining({
+            target: 'npx global-server',
+          }),
+        },
+        [getMcpProjectStateKey('/tmp/project-a')]: {
+          [getMcpDiagnosticKey('project-server', 'project')]: expect.objectContaining({
+            target: 'uvx project-server',
+          }),
+        },
+      });
+    });
+
+    it('refreshes MCP install state using the operation project context instead of the last viewed tab', async () => {
+      store.setState({
+        mcpInstalledProjectPath: '/tmp/project-b',
+      });
+      (api.mcpRegistry!.install as ReturnType<typeof vi.fn>).mockResolvedValue({ state: 'success' });
+      (api.mcpRegistry!.getInstalled as ReturnType<typeof vi.fn>).mockResolvedValue([]);
+      (api.mcpRegistry!.diagnose as ReturnType<typeof vi.fn>).mockResolvedValue([]);
+
+      await store.getState().installMcpServer({
+        registryId: 'test-id',
+        serverName: 'test-server',
+        scope: 'project',
+        projectPath: '/tmp/project-a',
+        envValues: {},
+        headers: [],
+      });
+
+      expect(api.mcpRegistry!.getInstalled).toHaveBeenLastCalledWith('/tmp/project-a');
+      expect(api.mcpRegistry!.diagnose).toHaveBeenLastCalledWith('/tmp/project-a');
+    });
   });
 
   describe('skills state hardening', () => {
diff --git a/test/shared/utils/extensionNormalizers.test.ts b/test/shared/utils/extensionNormalizers.test.ts
index de60b2ed..979c318d 100644
--- a/test/shared/utils/extensionNormalizers.test.ts
+++ b/test/shared/utils/extensionNormalizers.test.ts
@@ -166,8 +166,8 @@ describe('getPluginOperationKey', () => {
 
 describe('getMcpOperationKey', () => {
   it('namespaces MCP operation keys by scope', () => {
-    expect(getMcpOperationKey('io.github.upstash/context7', 'project')).toBe(
-      'mcp:io.github.upstash/context7:project',
+    expect(getMcpOperationKey('io.github.upstash/context7', 'project', '/tmp/project')).toBe(
+      'mcp:io.github.upstash/context7:project:/tmp/project',
     );
   });
 });