fix: prevent duplicate tabs when clicking file paths

Modify selectFile function to check for existing tabs before creating new ones.
When clicking file paths in AIChat, it will now switch to the existing tab
instead of creating duplicates.

frontend/components/editor/index.tsx

@@ -793,31 +793,32 @@ export default function CodeEditor({
     setGenerate((prev) => ({ ...prev, show: false }))
 
     // Check if the tab already exists in the list of open tabs
-    const exists = tabs.find((t) => t.id === tab.id)
-    setTabs((prev) => {
-      if (exists) {
-        // If the tab exists, make it the active tab
-        setActiveFileId(exists.id)
-        return prev
-      }
-      // If the tab doesn't exist, add it to the list of tabs and make it active
-      return [...prev, tab]
-    })
+    const existingTab = tabs.find((t) => t.id === tab.id)
 
-    // If the file's content is already cached, set it as the active content
-    if (fileContents[tab.id]) {
-      setActiveFileContent(fileContents[tab.id])
+    if (existingTab) {
+      // If the tab exists, just make it active
+      setActiveFileId(existingTab.id)
+      if (fileContents[existingTab.id]) {
+        setActiveFileContent(fileContents[existingTab.id])
+      }
     } else {
-      // Otherwise, fetch the content of the file and cache it
-      debouncedGetFile(tab.id, (response: string) => {
-        setFileContents((prev) => ({ ...prev, [tab.id]: response }))
-        setActiveFileContent(response)
-      })
+      // If the tab doesn't exist, add it to the list and make it active
+      setTabs((prev) => [...prev, tab])
+
+      // Fetch content if not cached
+      if (!fileContents[tab.id]) {
+        debouncedGetFile(tab.id, (response: string) => {
+          setFileContents((prev) => ({ ...prev, [tab.id]: response }))
+          setActiveFileContent(response)
+        })
+      } else {
+        setActiveFileContent(fileContents[tab.id])
+      }
     }
 
     // Set the editor language based on the file type
     setEditorLanguage(processFileType(tab.name))
-    // Set the active file ID to the new tab
+    // Set the active file ID
     setActiveFileId(tab.id)
   }