fix: migrate ProcessingPage from V1 batch API to V2 task API

Changes:
- Replace apiClient with apiClientV2 for task queries
- Update from batch status polling to task detail polling
- Change from batch_id to task_id (UUID string)
- Simplify UI to show single task instead of batch with multiple files
- Update redirect from /results to /tasks page
- Add task details card with timestamps
- Add error message display for failed tasks
- Calculate progress based on task status (pending: 0%, processing: 50%, completed/failed: 100%)

Fixes:
- 404 error: GET /api/v2/batch/{id}/status (endpoint no longer exists in V2)
- Continuous polling to non-existent batch endpoint

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/pages/ProcessingPage.tsx

@@ -8,18 +8,21 @@ import { Button } from '@/components/ui/button'
 import { Badge } from '@/components/ui/badge'
 import { useToast } from '@/components/ui/toast'
 import { useUploadStore } from '@/store/uploadStore'
-import { apiClient } from '@/services/api'
+import { apiClientV2 } from '@/services/apiV2'
 import { Play, CheckCircle, FileText, AlertCircle, Clock, Activity, Loader2 } from 'lucide-react'
 
 export default function ProcessingPage() {
   const { t } = useTranslation()
   const navigate = useNavigate()
   const { toast } = useToast()
-  const { batchId, files } = useUploadStore()
+  const { batchId } = useUploadStore()
+
+  // In V2, batchId is actually a task_id (string)
+  const taskId = batchId ? String(batchId) : null
 
   // Start OCR processing
   const processOCRMutation = useMutation({
-    mutationFn: () => apiClient.processOCR({ batch_id: batchId! }),
+    mutationFn: () => apiClientV2.startTask(taskId!),
     onSuccess: () => {
       toast({
         title: '開始處理',
@@ -36,16 +39,16 @@ export default function ProcessingPage() {
     },
   })
 
-  // Poll batch status
-  const { data: batchStatus } = useQuery({
-    queryKey: ['batchStatus', batchId],
-    queryFn: () => apiClient.getBatchStatus(batchId!),
-    enabled: !!batchId,
+  // Poll task status
+  const { data: taskDetail } = useQuery({
+    queryKey: ['taskDetail', taskId],
+    queryFn: () => apiClientV2.getTask(taskId!),
+    enabled: !!taskId,
     refetchInterval: (query) => {
       const data = query.state.data
       if (!data) return 2000
       // Stop polling if completed or failed
-      if (data.batch.status === 'completed' || data.batch.status === 'failed') {
+      if (data.status === 'completed' || data.status === 'failed') {
         return false
       }
       return 2000 // Poll every 2 seconds
@@ -54,19 +57,19 @@ export default function ProcessingPage() {
 
   // Auto-redirect when completed
   useEffect(() => {
-    if (batchStatus?.batch.status === 'completed') {
+    if (taskDetail?.status === 'completed') {
       setTimeout(() => {
-        navigate('/results')
+        navigate('/tasks')
       }, 1000)
     }
-  }, [batchStatus?.batch.status, navigate])
+  }, [taskDetail?.status, navigate])
 
   const handleStartProcessing = () => {
     processOCRMutation.mutate()
   }
 
   const handleViewResults = () => {
-    navigate('/results')
+    navigate('/tasks')
   }
 
   const getStatusBadge = (status: string) => {
@@ -82,8 +85,21 @@ export default function ProcessingPage() {
     }
   }
 
-  // Show helpful message when no batch is selected
-  if (!batchId) {
+  const getProgressPercentage = (status: string) => {
+    switch (status) {
+      case 'completed':
+        return 100
+      case 'processing':
+        return 50
+      case 'failed':
+        return 100
+      default:
+        return 0
+    }
+  }
+
+  // Show helpful message when no task is selected
+  if (!taskId) {
     return (
       <div className="flex items-center justify-center min-h-[60vh]">
         <Card className="max-w-md text-center">
@@ -97,7 +113,7 @@ export default function ProcessingPage() {
           </CardHeader>
           <CardContent className="space-y-4">
             <p className="text-muted-foreground">
-              {t('processing.noBatchMessage', { defaultValue: '尚未選擇任何批次。請先上傳檔案以建立批次。' })}
+              {t('processing.noBatchMessage', { defaultValue: '尚未選擇任何任務。請先上傳檔案以建立任務。' })}
             </p>
             <Button
               onClick={() => navigate('/upload')}
@@ -111,9 +127,9 @@ export default function ProcessingPage() {
     )
   }
 
-  const isProcessing = batchStatus?.batch.status === 'processing'
-  const isCompleted = batchStatus?.batch.status === 'completed'
-  const isPending = !batchStatus || batchStatus.batch.status === 'pending'
+  const isProcessing = taskDetail?.status === 'processing'
+  const isCompleted = taskDetail?.status === 'completed'
+  const isPending = !taskDetail || taskDetail.status === 'pending'
 
   return (
     <div className="space-y-6">
@@ -123,7 +139,8 @@ export default function ProcessingPage() {
           <div>
             <h1 className="page-title">{t('processing.title')}</h1>
             <p className="text-muted-foreground mt-1">
-              批次 ID: <span className="font-mono text-primary">{batchId}</span> · 共 {files.length} 個檔案
+              任務 ID: <span className="font-mono text-primary">{taskId}</span>
+              {taskDetail?.filename && ` · ${taskDetail.filename}`}
             </p>
           </div>
           <div>
@@ -153,7 +170,7 @@ export default function ProcessingPage() {
               </div>
               <CardTitle>{t('processing.progress')}</CardTitle>
             </div>
-            {batchStatus && getStatusBadge(batchStatus.batch.status)}
+            {taskDetail && getStatusBadge(taskDetail.status)}
           </div>
         </CardHeader>
         <CardContent className="space-y-6">
@@ -162,63 +179,58 @@ export default function ProcessingPage() {
             <div className="flex justify-between text-sm mb-3">
               <span className="text-muted-foreground font-medium">{t('processing.status')}</span>
               <span className="font-bold text-xl text-primary">
-                {batchStatus?.batch.progress_percentage || 0}%
+                {taskDetail ? getProgressPercentage(taskDetail.status) : 0}%
               </span>
             </div>
-            <Progress value={batchStatus?.batch.progress_percentage || 0} max={100} className="h-4" />
+            <Progress
+              value={taskDetail ? getProgressPercentage(taskDetail.status) : 0}
+              max={100}
+              className="h-4"
+            />
           </div>
 
-          {/* Stats */}
-          {batchStatus && (
-            <div className="grid grid-cols-1 md:grid-cols-4 gap-4">
-              <div className="p-4 bg-muted/30 rounded-lg border border-border">
-                <div className="flex items-center gap-3">
-                  <div className="p-2 bg-success/10 rounded-lg">
-                    <CheckCircle className="w-5 h-5 text-success" />
-                  </div>
-                  <div>
-                    <p className="text-xs text-muted-foreground mb-0.5">已完成</p>
-                    <p className="text-2xl font-bold text-foreground">
-                      {batchStatus.files.filter((f) => f.status === 'completed').length}
-                    </p>
-                  </div>
-                </div>
-              </div>
+          {/* Task Info */}
+          {taskDetail && (
+            <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
               <div className="p-4 bg-muted/30 rounded-lg border border-border">
                 <div className="flex items-center gap-3">
                   <div className="p-2 bg-primary/10 rounded-lg">
-                    <Loader2 className="w-5 h-5 text-primary" />
+                    <FileText className="w-5 h-5 text-primary" />
                   </div>
                   <div>
-                    <p className="text-xs text-muted-foreground mb-0.5">處理中</p>
-                    <p className="text-2xl font-bold text-foreground">
-                      {batchStatus.files.filter((f) => f.status === 'processing').length}
+                    <p className="text-xs text-muted-foreground mb-0.5">檔案名稱</p>
+                    <p className="text-sm font-medium text-foreground truncate">
+                      {taskDetail.filename || '未知檔案'}
                     </p>
                   </div>
                 </div>
               </div>
+              {taskDetail.processing_time_ms && (
                 <div className="p-4 bg-muted/30 rounded-lg border border-border">
                   <div className="flex items-center gap-3">
-                  <div className="p-2 bg-destructive/10 rounded-lg">
-                    <AlertCircle className="w-5 h-5 text-destructive" />
+                    <div className="p-2 bg-success/10 rounded-lg">
+                      <Clock className="w-5 h-5 text-success" />
                     </div>
                     <div>
-                    <p className="text-xs text-muted-foreground mb-0.5">失敗</p>
-                    <p className="text-2xl font-bold text-foreground">
-                      {batchStatus.files.filter((f) => f.status === 'failed').length}
+                      <p className="text-xs text-muted-foreground mb-0.5">處理時間</p>
+                      <p className="text-sm font-medium text-foreground">
+                        {(taskDetail.processing_time_ms / 1000).toFixed(2)}s
                       </p>
                     </div>
                   </div>
                 </div>
-              <div className="p-4 bg-muted/30 rounded-lg border border-border">
-                <div className="flex items-center gap-3">
-                  <div className="p-2 bg-muted rounded-lg">
-                    <FileText className="w-5 h-5 text-muted-foreground" />
+              )}
             </div>
+          )}
+
+          {/* Error message */}
+          {taskDetail?.error_message && (
+            <div className="p-4 bg-destructive/10 rounded-lg border border-destructive/20">
+              <div className="flex items-start gap-3">
+                <AlertCircle className="w-5 h-5 text-destructive flex-shrink-0 mt-0.5" />
                 <div>
-                    <p className="text-xs text-muted-foreground mb-0.5">總計</p>
-                    <p className="text-2xl font-bold text-foreground">{batchStatus.files.length}</p>
-                  </div>
+                  <p className="text-sm font-medium text-destructive mb-1">處理失敗</p>
+                  <p className="text-sm text-destructive/80">{taskDetail.error_message}</p>
                 </div>
               </div>
             </div>
@@ -255,7 +267,7 @@ export default function ProcessingPage() {
                   size="lg"
                 >
                   <CheckCircle className="w-4 h-4" />
-                  {t('common.next')}
+                  查看任務歷史
                 </Button>
               )}
             </div>
@@ -263,64 +275,45 @@ export default function ProcessingPage() {
         </CardContent>
       </Card>
 
-      {/* File List */}
-      {batchStatus && (
+      {/* Task Details Card */}
+      {taskDetail && (
         <Card>
           <CardHeader>
             <div className="flex items-center gap-3">
               <div className="p-2 bg-primary/10 rounded-lg">
                 <FileText className="w-5 h-5 text-primary" />
               </div>
-              <CardTitle>檔案處理狀態</CardTitle>
+              <CardTitle>任務詳情</CardTitle>
             </div>
           </CardHeader>
           <CardContent>
-            <div className="space-y-2">
-              {batchStatus.files.map((file) => (
-                <div
-                  key={file.id}
-                  className="flex items-center justify-between p-4 rounded-lg border border-border hover:bg-muted/50 transition-colors"
-                >
-                  <div className="flex items-center gap-4 flex-1 min-w-0">
-                    <div className={`p-2 rounded-lg ${
-                      file.status === 'completed' ? 'bg-success/10' :
-                      file.status === 'processing' ? 'bg-primary/10' :
-                      file.status === 'failed' ? 'bg-destructive/10' :
-                      'bg-muted'
-                    }`}>
-                      {file.status === 'completed' ? (
-                        <CheckCircle className="w-5 h-5 text-success" />
-                      ) : file.status === 'processing' ? (
-                        <Loader2 className="w-5 h-5 text-primary animate-spin" />
-                      ) : file.status === 'failed' ? (
-                        <AlertCircle className="w-5 h-5 text-destructive" />
-                      ) : (
-                        <FileText className="w-5 h-5 text-muted-foreground" />
+            <div className="space-y-3">
+              <div className="flex justify-between py-2 border-b border-border">
+                <span className="text-sm text-muted-foreground">任務狀態</span>
+                {getStatusBadge(taskDetail.status)}
+              </div>
+              <div className="flex justify-between py-2 border-b border-border">
+                <span className="text-sm text-muted-foreground">建立時間</span>
+                <span className="text-sm font-medium">
+                  {new Date(taskDetail.created_at).toLocaleString('zh-TW')}
+                </span>
+              </div>
+              {taskDetail.updated_at && (
+                <div className="flex justify-between py-2 border-b border-border">
+                  <span className="text-sm text-muted-foreground">更新時間</span>
+                  <span className="text-sm font-medium">
+                    {new Date(taskDetail.updated_at).toLocaleString('zh-TW')}
+                  </span>
+                </div>
               )}
+              {taskDetail.completed_at && (
+                <div className="flex justify-between py-2 border-b border-border">
+                  <span className="text-sm text-muted-foreground">完成時間</span>
+                  <span className="text-sm font-medium">
+                    {new Date(taskDetail.completed_at).toLocaleString('zh-TW')}
+                  </span>
                 </div>
-                    <div className="flex-1 min-w-0">
-                      <p className="text-sm font-medium text-foreground truncate">
-                        {file.filename}
-                      </p>
-                      <div className="flex items-center gap-3 mt-1">
-                        {file.processing_time && (
-                          <p className="text-xs text-muted-foreground flex items-center gap-1">
-                            <Clock className="w-3 h-3" />
-                            處理時間: {file.processing_time.toFixed(2)}s
-                          </p>
               )}
-                        {file.error && (
-                          <p className="text-xs text-destructive flex items-center gap-1">
-                            <AlertCircle className="w-3 h-3" />
-                            {file.error}
-                          </p>
-                        )}
-                      </div>
-                    </div>
-                  </div>
-                  {getStatusBadge(file.status)}
-                </div>
-              ))}
             </div>
           </CardContent>
         </Card>