diff --git a/frontend/app/analysis/page.tsx b/frontend/app/analysis/page.tsx
index f1b262bc..353206e3 100644
--- a/frontend/app/analysis/page.tsx
+++ b/frontend/app/analysis/page.tsx
@@ -21,7 +21,7 @@ export default function AnalysisPage() {
   const { setAnalysisResult, setTaskId, setMarketType, marketType } = useAnalysisContext();
   const { runAnalysis, loading, error, result, taskId } = useAnalysis();
   const { isAuthenticated } = useAuth();
-  const { t } = useLanguage();
+  const { t, locale } = useLanguage();
   
   // Ref to track if we've already saved (to prevent duplicate saves)
   const hasSavedRef = useRef(false);
@@ -47,7 +47,8 @@ export default function AnalysisPage() {
         marketType,
         result.analysis_date,
         result,
-        taskId || undefined
+        taskId || undefined,
+        locale as "en" | "zh-TW"  // Pass current language for filtering
       );
       console.log("📁 Auto-saved report to local storage");
       
@@ -58,6 +59,7 @@ export default function AnalysisPage() {
           market_type: marketType,
           analysis_date: result.analysis_date,
           result: result,
+          language: locale as "en" | "zh-TW",
         });
         if (cloudId) {
           console.log("☁️ Auto-saved report to cloud");
@@ -68,7 +70,7 @@ export default function AnalysisPage() {
     } catch (error) {
       console.error("Auto-save failed:", error);
     }
-  }, [result, marketType, taskId, isAuthenticated]);
+  }, [result, marketType, taskId, isAuthenticated, locale]);
 
   // Auto-save when page unloads (closing tab, navigating away, etc.)
   useEffect(() => {
diff --git a/frontend/app/analysis/results/page.tsx b/frontend/app/analysis/results/page.tsx
index 07396223..67a64971 100644
--- a/frontend/app/analysis/results/page.tsx
+++ b/frontend/app/analysis/results/page.tsx
@@ -97,7 +97,8 @@ export default function AnalysisResultsPage() {
         marketType,
         analysisResult.analysis_date,
         analysisResult,
-        taskId || undefined
+        taskId || undefined,
+        locale as "en" | "zh-TW"  // Pass current language for filtering
       );
       
       // If authenticated, also save to cloud
@@ -107,6 +108,7 @@ export default function AnalysisResultsPage() {
           market_type: marketType,
           analysis_date: analysisResult.analysis_date,
           result: analysisResult,
+          language: locale as "en" | "zh-TW",
         });
         if (cloudId) {
           setSavedToCloud(true);
diff --git a/frontend/app/history/page.tsx b/frontend/app/history/page.tsx
index 2c7c2421..cdca3d7c 100644
--- a/frontend/app/history/page.tsx
+++ b/frontend/app/history/page.tsx
@@ -207,6 +207,41 @@ const extractDecisionFromReport = (report: SavedReport): { action: string; color
   return { action: "N/A", color: "text-gray-500" };
 };
 
+/**
+ * Detect report language from content (for backward compatibility with old reports)
+ * Checks trader_investment_plan for Chinese/English keywords
+ */
+const detectReportLanguage = (reports: any): "en" | "zh-TW" => {
+  const traderPlan = reports?.trader_investment_plan;
+  if (!traderPlan || typeof traderPlan !== 'string') {
+    // If no trader plan, check other reports for Chinese characters
+    const allText = JSON.stringify(reports || {});
+    const chineseRegex = /[\u4e00-\u9fa5]/;
+    return chineseRegex.test(allText) ? 'zh-TW' : 'en';
+  }
+  
+  // Check for Chinese decision keywords
+  const chineseKeywords = ['買入', '賣出', '持有', '最終交易提案'];
+  for (const keyword of chineseKeywords) {
+    if (traderPlan.includes(keyword)) {
+      return 'zh-TW';
+    }
+  }
+  
+  // Check for English decision keywords
+  const englishKeywords = ['buy', 'sell', 'hold', 'Final Trading Proposal'];
+  const lowerPlan = traderPlan.toLowerCase();
+  for (const keyword of englishKeywords) {
+    if (lowerPlan.includes(keyword.toLowerCase())) {
+      return 'en';
+    }
+  }
+  
+  // Fallback: check for Chinese characters in the content
+  const chineseRegex = /[\u4e00-\u9fa5]/;
+  return chineseRegex.test(traderPlan) ? 'zh-TW' : 'en';
+};
+
 export default function HistoryPage() {
   const router = useRouter();
   const { setAnalysisResult, setTaskId, setMarketType } = useAnalysisContext();
@@ -232,10 +267,10 @@ export default function HistoryPage() {
   // Auto-sync tracking ref
   const hasAutoSyncedRef = useRef(false);
 
-  // Load reports when tab changes or auth state changes
+  // Load reports when tab changes, auth state changes, or language changes
   useEffect(() => {
     loadReports();
-  }, [activeTab, isAuthenticated]);
+  }, [activeTab, isAuthenticated, locale]);
 
   // Load counts on mount or auth change
   useEffect(() => {
@@ -332,6 +367,7 @@ export default function HistoryPage() {
             analysis_date: r.analysis_date,
             saved_at: new Date(r.created_at),
             result: r.result,
+            language: r.language, // Include language from cloud
           })) as (SavedReport & { cloudId?: string })[];
         
         if (cloudFiltered.length > 0) {
@@ -354,20 +390,43 @@ export default function HistoryPage() {
             new Date(b.saved_at).getTime() - new Date(a.saved_at).getTime()
           );
           
-          setReports(merged);
+          // Filter by current language
+          const languageFiltered = merged.filter(report => {
+            // Use stored language if available
+            if (report.language) {
+              return report.language === locale;
+            }
+            // Fallback: detect from content for old reports without language field
+            return detectReportLanguage(report.result?.reports) === locale;
+          });
+          
+          setReports(languageFiltered);
           setIsCloudData(true);
           return;
         }
       }
       
       // If no cloud data or not authenticated, use local only
-      setReports(localData);
+      // Filter by current language
+      const languageFiltered = localData.filter(report => {
+        if (report.language) {
+          return report.language === locale;
+        }
+        return detectReportLanguage(report.result?.reports) === locale;
+      });
+      setReports(languageFiltered);
       setIsCloudData(false);
     } catch (error) {
       console.error("Failed to load reports:", error);
       // Fall back to local on error
       const data = await getReportsByMarketType(activeTab);
-      setReports(data);
+      const languageFiltered = data.filter(report => {
+        if (report.language) {
+          return report.language === locale;
+        }
+        return detectReportLanguage(report.result?.reports) === locale;
+      });
+      setReports(languageFiltered);
       setIsCloudData(false);
     } finally {
       setLoading(false);
diff --git a/frontend/components/PendingTaskRecovery.tsx b/frontend/components/PendingTaskRecovery.tsx
index e4ee8e4c..b8ec59f6 100644
--- a/frontend/components/PendingTaskRecovery.tsx
+++ b/frontend/components/PendingTaskRecovery.tsx
@@ -13,12 +13,14 @@ import { getPendingTask, clearPendingTask, isPendingTaskValid, type PendingTask
 import { saveReport, checkDuplicateReport } from "@/lib/reports-db";
 import { saveCloudReport, isCloudSyncEnabled } from "@/lib/user-api";
 import { useAuth } from "@/contexts/auth-context";
+import { useLanguage } from "@/contexts/LanguageContext";
 
 export function PendingTaskRecovery() {
   const [pendingTask, setPendingTask] = useState<PendingTask | null>(null);
   const [status, setStatus] = useState<'checking' | 'found' | 'recovering' | 'success' | 'failed' | 'not_found'>('checking');
   const [message, setMessage] = useState<string>("");
   const { isAuthenticated } = useAuth();
+  const { locale } = useLanguage();
 
   useEffect(() => {
     // Check for pending tasks on mount
@@ -72,7 +74,8 @@ export function PendingTaskRecovery() {
           pendingTask.marketType,
           taskStatus.result.analysis_date,
           taskStatus.result,
-          pendingTask.taskId
+          pendingTask.taskId,
+          locale as "en" | "zh-TW"  // Pass current language for filtering
         );
         
         // If authenticated, also save to cloud
@@ -82,6 +85,7 @@ export function PendingTaskRecovery() {
             market_type: pendingTask.marketType,
             analysis_date: taskStatus.result.analysis_date,
             result: taskStatus.result,
+            language: locale as "en" | "zh-TW",
           });
         }
         
@@ -121,7 +125,7 @@ export function PendingTaskRecovery() {
         setStatus('failed');
       }
     }
-  }, [pendingTask, isAuthenticated]);
+  }, [pendingTask, isAuthenticated, locale]);
 
   const handleDismiss = () => {
     clearPendingTask();
diff --git a/frontend/contexts/auth-context.tsx b/frontend/contexts/auth-context.tsx
index da16acaf..064753d0 100644
--- a/frontend/contexts/auth-context.tsx
+++ b/frontend/contexts/auth-context.tsx
@@ -219,7 +219,8 @@ export function AuthProvider({ children }: { children: ReactNode }) {
             report.market_type,
             report.analysis_date,
             report.result,
-            (report as any).task_id
+            (report as any).task_id,
+            report.language  // Preserve language from cloud
           );
         }
         console.log(`Restored ${cloudReports.length} reports from cloud`);
diff --git a/frontend/lib/reports-db.ts b/frontend/lib/reports-db.ts
index 7e3cee67..89f9485c 100644
--- a/frontend/lib/reports-db.ts
+++ b/frontend/lib/reports-db.ts
@@ -15,6 +15,7 @@ export interface SavedReport {
   saved_at: Date; // Save timestamp
   task_id?: string; // Original task ID
   result: AnalysisResponse; // Full analysis result
+  language?: "en" | "zh-TW"; // Language of the report (for filtering)
 }
 
 // Database class extending Dexie
@@ -23,10 +24,14 @@ class ReportsDatabase extends Dexie {
 
   constructor() {
     super("TradingAgentsReports");
+    // Version 1: Original schema
     this.version(1).stores({
-      // Define indexes: ++id = auto-increment, others are indexed fields
       reports: "++id, ticker, market_type, analysis_date, saved_at",
     });
+    // Version 2: Added language field for filtering by UI language
+    this.version(2).stores({
+      reports: "++id, ticker, market_type, analysis_date, saved_at, language",
+    });
   }
 }
 
@@ -41,7 +46,8 @@ export async function saveReport(
   market_type: "us" | "twse" | "tpex",
   analysis_date: string,
   result: AnalysisResponse,
-  task_id?: string
+  task_id?: string,
+  language?: "en" | "zh-TW",
 ): Promise<number> {
   const report: SavedReport = {
     ticker,
@@ -50,6 +56,7 @@ export async function saveReport(
     saved_at: new Date(),
     task_id,
     result,
+    language,
   };
 
   return await db.reports.add(report);
@@ -59,7 +66,7 @@ export async function saveReport(
  * Get all reports by market type
  */
 export async function getReportsByMarketType(
-  market_type: "us" | "twse" | "tpex"
+  market_type: "us" | "twse" | "tpex",
 ): Promise<SavedReport[]> {
   return await db.reports
     .where("market_type")
@@ -79,7 +86,7 @@ export async function getAllReports(): Promise<SavedReport[]> {
  * Get a single report by ID
  */
 export async function getReportById(
-  id: number
+  id: number,
 ): Promise<SavedReport | undefined> {
   return await db.reports.get(id);
 }
@@ -120,7 +127,7 @@ export async function getReportCountByMarketType(): Promise<{
  */
 export async function checkDuplicateReport(
   ticker: string,
-  analysis_date: string
+  analysis_date: string,
 ): Promise<SavedReport | undefined> {
   return await db.reports
     .where("ticker")
diff --git a/frontend/lib/user-api.ts b/frontend/lib/user-api.ts
index 2755b5c6..03f0b620 100644
--- a/frontend/lib/user-api.ts
+++ b/frontend/lib/user-api.ts
@@ -15,6 +15,7 @@ interface CloudReport {
   analysis_date: string;
   result: any;
   created_at: string;
+  language?: "en" | "zh-TW"; // Language of the report
 }
 
 /**
@@ -102,6 +103,7 @@ export async function saveCloudReport(report: {
   market_type: "us" | "twse" | "tpex";
   analysis_date: string;
   result: any;
+  language?: "en" | "zh-TW";
 }): Promise<string | null> {
   if (!isCloudSyncEnabled()) {
     console.warn("☁️ Cloud sync not enabled (no auth token)");