diff --git a/ui/desktop/src/components/ExtensionInstallModal.test.tsx b/ui/desktop/src/components/ExtensionInstallModal.test.tsx
index 057451f56a90..f32e6123ea56 100644
--- a/ui/desktop/src/components/ExtensionInstallModal.test.tsx
+++ b/ui/desktop/src/components/ExtensionInstallModal.test.tsx
@@ -19,6 +19,13 @@ const mockElectron = {
 
 (window as any).electron = mockElectron;
 
+vi.mock('./ConfigContext', () => ({
+  useConfig: () => ({
+    extensionsList: [],
+    getExtensions: vi.fn().mockResolvedValue([]),
+  }),
+}));
+
 describe('ExtensionInstallModal', () => {
   const mockAddExtension = vi.fn();
   const mockSetView = vi.fn();
diff --git a/ui/desktop/src/components/ExtensionInstallModal.tsx b/ui/desktop/src/components/ExtensionInstallModal.tsx
index 0478730c53c2..3b5153ee1dfc 100644
--- a/ui/desktop/src/components/ExtensionInstallModal.tsx
+++ b/ui/desktop/src/components/ExtensionInstallModal.tsx
@@ -1,4 +1,4 @@
-import { useState, useCallback, useEffect } from 'react';
+import { useState, useCallback, useEffect, useRef } from 'react';
 import { IpcRendererEvent } from 'electron';
 import {
   Dialog,
@@ -13,6 +13,8 @@ import { extractExtensionName } from './settings/extensions/utils';
 import { addExtensionFromDeepLink } from './settings/extensions/deeplink';
 import type { ExtensionConfig } from '../api/types.gen';
 import { View, ViewOptions } from '../utils/navigationUtils';
+import { useConfig } from './ConfigContext';
+import { toastService } from '../toasts';
 
 type ModalType = 'blocked' | 'untrusted' | 'trusted';
 
@@ -66,6 +68,14 @@ function extractRemoteUrl(link: string): string | null {
 }
 
 export function ExtensionInstallModal({ addExtension, setView }: ExtensionInstallModalProps) {
+  const { getExtensions } = useConfig();
+  const getExtensionsRef = useRef(getExtensions);
+  const processingLinkRef = useRef<string | null>(null);
+
+  useEffect(() => {
+    getExtensionsRef.current = getExtensions;
+  }, [getExtensions]);
+
   const [modalState, setModalState] = useState<ExtensionModalState>({
     isOpen: false,
     modalType: 'trusted',
@@ -149,12 +159,30 @@ export function ExtensionInstallModal({ addExtension, setView }: ExtensionInstal
   };
 
   const handleExtensionRequest = useCallback(async (link: string): Promise<void> => {
+    if (processingLinkRef.current === link) {
+      console.log(`Skipping duplicate extension request (already processing): ${link}`);
+      return;
+    }
+    processingLinkRef.current = link;
+
     try {
       console.log(`Processing extension request: ${link}`);
 
       const command = extractCommand(link);
       const remoteUrl = extractRemoteUrl(link);
       const extName = extractExtensionName(link);
+      const extensionsList = await getExtensionsRef.current(true);
+
+      if (extensionsList?.find((ext) => ext.name === extName)) {
+        console.log(`Extension Already Installed: ${extName}`);
+
+        toastService.success({
+          title: `Extension '${extName}' Already Installed`,
+          msg: `'${extName}' extension has already been installed successfully. Start a new chat session to use it.`,
+        });
+        return;
+      }
+      console.log('Extension not found, continuing to show modal');
 
       const extensionInfo: ExtensionInfo = {
         name: extName,
@@ -182,6 +210,8 @@ export function ExtensionInstallModal({ addExtension, setView }: ExtensionInstal
         ...prev,
         error: error instanceof Error ? error.message : 'Unknown error',
       }));
+    } finally {
+      processingLinkRef.current = null;
     }
   }, []);
 
@@ -285,7 +315,7 @@ export function ExtensionInstallModal({ addExtension, setView }: ExtensionInstal
       <DialogContent className="sm:max-w-[500px]">
         <DialogHeader>
           <DialogTitle className={getTitleClassName()}>{config.title}</DialogTitle>
-          <DialogDescription className="whitespace-pre-wrap text-left">
+          <DialogDescription className="text-left whitespace-pre-wrap">
             {config.message}
           </DialogDescription>
         </DialogHeader>