fix: handle navigation when all files are harmful content

When all uploaded files contain harmful content, the backend processes
them very fast (before WebSocket connects), causing the UI to get stuck
loading indefinitely. This fix:

- Detects already-completed batches on initial fetch and navigates directly
- Checks both batch status and individual file terminal states
- Adds navigation guard (useRef) to prevent duplicate navigations
- Prevents resetting allFilesCompleted state after it's been finalized

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Shreyas-Microsoft

src/frontend/src/pages/modernizationPage.tsx

@@ -31,7 +31,7 @@ import { Light as SyntaxHighlighter } from "react-syntax-highlighter"
 import { vs } from "react-syntax-highlighter/dist/esm/styles/hljs"
 import sql from "react-syntax-highlighter/dist/cjs/languages/hljs/sql"
 import { useNavigate, useParams } from "react-router-dom"
-import { useState, useEffect, useCallback } from "react"
+import { useState, useEffect, useCallback, useRef } from "react"
 import { getApiUrl, headerBuilder } from '../api/config';
 import BatchHistoryPanel from "../components/batchHistoryPanel"
 import PanelRight from "../components/Panels/PanelRight";
@@ -501,6 +501,7 @@ const ModernizationPage = () => {
   const [isZipButtonDisabled, setIsZipButtonDisabled] = useState(true);
   const [fileLoading, setFileLoading] = useState(false);
   const [lastActivityTime, setLastActivityTime] = useState<number>(Date.now());
+  const hasNavigatedRef = useRef(false);
   //const [pageLoadTime] = useState<number>(Date.now());
 
   // Fetch file content when a file is selected
@@ -536,12 +537,22 @@ const ModernizationPage = () => {
       setBatchSummary(data);
       if (data) {
 
-        const batchCompleted = data.status?.toLowerCase() === "completed" || data.status === "failed";
-        if (batchCompleted) {
+        const batchCompleted = data.status?.toLowerCase() === "completed" || data.status?.toLowerCase() === "failed";
+        const allFilesTerminal = data.files.every((file: any) =>
+          ["completed", "failed", "error"].includes(file.status?.toLowerCase() || "")
+        );
+
+        if (batchCompleted || allFilesTerminal) {
           setAllFilesCompleted(true);
           if (data.hasFiles > 0) {
             setIsZipButtonDisabled(false);
           }
+          // Batch already finished (e.g., all files were harmful content) — navigate directly
+          if (!hasNavigatedRef.current) {
+            hasNavigatedRef.current = true;
+            navigate(`/batch-view/${batchId}`);
+            return;
+          }
         }
         // Transform the server response to an array of your FileItem objects
         const fileItems: FileItem[] = data.files.map((file: any, index: number) => ({
@@ -725,7 +736,10 @@ const ModernizationPage = () => {
   // Update files state when Redux fileList changes
   useEffect(() => {
     if (reduxFileList && reduxFileList.length > 0) {
-      setAllFilesCompleted(false);
+      // Only reset completion state if not already finalized
+      if (!allFilesCompleted) {
+        setAllFilesCompleted(false);
+      }
       // Map the Redux fileList to our FileItem format
       const fileItems: FileItem[] = reduxFileList.filter(file => file.type !== 'summary').map((file: any, index: number) => ({
 
@@ -832,8 +846,11 @@ const ModernizationPage = () => {
         });
 
         // Navigate only after all files have reached terminal states.
-        console.log("Processing complete (all files done), navigating to batch view page");
-        navigate(`/batch-view/${batchId}`);
+        if (!hasNavigatedRef.current) {
+          hasNavigatedRef.current = true;
+          console.log("Processing complete (all files done), navigating to batch view page");
+          navigate(`/batch-view/${batchId}`);
+        }
       }
     } catch (err) {
       console.error("Failed to update summary status:", err);