feat: Added missing status badge, Library filter/re-download button, an…

- "src/frontend/src/components/StatusBadge.tsx"
- "src/frontend/src/pages/Library.tsx"
- "src/frontend/src/pages/System.tsx"
- "src/frontend/src/api/hooks/useLibrary.ts"
- "src/frontend/src/api/hooks/useSystem.ts"

GSD-Task: S06/T03

src/frontend/src/api/hooks/useLibrary.ts

@@ -1,4 +1,4 @@
-import { useQuery } from '@tanstack/react-query';
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import { apiClient } from '../client';
 import type { ContentItem, ContentStatus, ContentType } from '@shared/types/index';
 import type { PaginatedResponse } from '@shared/types/api';
@@ -44,3 +44,17 @@ export function useLibraryContent(filters: LibraryFilters = {}) {
     },
   });
 }
+
+// ── Mutations ──
+
+/** Re-download a missing content item. Invalidates library queries on success. */
+export function useRequeueContent() {
+  const queryClient = useQueryClient();
+  return useMutation({
+    mutationFn: (contentId: number) =>
+      apiClient.post(`/api/v1/content/${contentId}/requeue`),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: libraryKeys.all });
+    },
+  });
+}

src/frontend/src/api/hooks/useSystem.ts

@@ -10,6 +10,7 @@ export const systemKeys = {
   apiKey: ['system', 'apikey'] as const,
   appSettings: ['system', 'appSettings'] as const,
   ytdlpStatus: ['system', 'ytdlpStatus'] as const,
+  missingScanStatus: ['system', 'missingScanStatus'] as const,
 };
 
 // ── Queries ──
@@ -91,3 +92,44 @@ export function useUpdateYtDlp() {
     },
   });
 }
+
+// ── Missing File Scan ──
+
+interface ScanResult {
+  checked: number;
+  missing: number;
+  duration: number;
+}
+
+interface MissingScanStatusResponse {
+  lastRun: string;
+  result: ScanResult;
+}
+
+interface MissingScanTriggerResponse {
+  success: boolean;
+  data: ScanResult;
+}
+
+/** Fetch last missing file scan status. Does not auto-refresh. */
+export function useMissingScanStatus() {
+  return useQuery({
+    queryKey: systemKeys.missingScanStatus,
+    queryFn: () =>
+      apiClient.get<{ success: boolean; data: MissingScanStatusResponse | null }>(
+        '/api/v1/system/missing-scan/status',
+      ),
+  });
+}
+
+/** Trigger an on-demand missing file scan. Invalidates scan status on success. */
+export function useTriggerMissingScan() {
+  const queryClient = useQueryClient();
+  return useMutation({
+    mutationFn: () =>
+      apiClient.post<MissingScanTriggerResponse>('/api/v1/system/missing-scan'),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: systemKeys.missingScanStatus });
+    },
+  });
+}

src/frontend/src/components/StatusBadge.tsx

@@ -16,6 +16,7 @@ const STATUS_STYLES: Record<string, BadgeStyle> = {
   downloading: { color: 'var(--info)', backgroundColor: 'var(--info-bg)' },
   failed: { color: 'var(--danger)', backgroundColor: 'var(--danger-bg)' },
   queued: { color: 'var(--warning)', backgroundColor: 'var(--warning-bg)' },
+  missing: { color: 'var(--warning)', backgroundColor: 'var(--warning-bg)' },
   ignored: { color: 'var(--text-muted)', backgroundColor: 'var(--bg-hover)' },
   // Queue statuses
   pending: { color: 'var(--warning)', backgroundColor: 'var(--warning-bg)' },

src/frontend/src/pages/Library.tsx

@@ -1,6 +1,6 @@
 import { useState, useCallback, useMemo } from 'react';
 import { useNavigate } from 'react-router-dom';
-import { Library as LibraryIcon, RefreshCw, Film, Music } from 'lucide-react';
+import { Library as LibraryIcon, RefreshCw, Film, Music, RotateCcw } from 'lucide-react';
 import { Table, type Column } from '../components/Table';
 import { StatusBadge } from '../components/StatusBadge';
 import { QualityLabel } from '../components/QualityLabel';
@@ -9,7 +9,7 @@ import { Pagination } from '../components/Pagination';
 import { SearchBar } from '../components/SearchBar';
 import { FilterBar, type FilterDefinition } from '../components/FilterBar';
 import { SkeletonLibrary } from '../components/Skeleton';
-import { useLibraryContent, type LibraryFilters } from '../api/hooks/useLibrary';
+import { useLibraryContent, useRequeueContent, type LibraryFilters } from '../api/hooks/useLibrary';
 import { useChannels } from '../api/hooks/useChannels';
 import { formatDuration, formatFileSize } from '../utils/format';
 import type { ContentItem, ContentStatus, ContentType } from '@shared/types/index';
@@ -44,6 +44,7 @@ export function Library() {
   // Queries
   const { data, isLoading, error, refetch } = useLibraryContent(filters);
   const { data: channels } = useChannels();
+  const requeue = useRequeueContent();
 
   // Reset to page 1 when filters change
   const handleSearchChange = useCallback((value: string) => {
@@ -80,6 +81,7 @@ export function Library() {
           { value: 'downloading', label: 'Downloading' },
           { value: 'downloaded', label: 'Downloaded' },
           { value: 'failed', label: 'Failed' },
+          { value: 'missing', label: 'Missing' },
           { value: 'ignored', label: 'Ignored' },
         ],
       },
@@ -260,8 +262,30 @@ export function Library() {
           </span>
         ),
       },
+      {
+        key: 'actions',
+        label: '',
+        width: '110px',
+        render: (item) =>
+          item.status === 'missing' ? (
+            <button
+              onClick={(e) => {
+                e.stopPropagation();
+                requeue.mutate(item.id);
+              }}
+              disabled={requeue.isPending}
+              className="btn btn-warning"
+              style={{ fontSize: 'var(--font-size-xs)', padding: '2px var(--space-2)', gap: 'var(--space-1)' }}
+              title="Re-download this item"
+              aria-label={`Re-download ${item.title}`}
+            >
+              <RotateCcw size={12} />
+              Re-download
+            </button>
+          ) : null,
+      },
     ],
-    [channels, navigate],
+    [channels, navigate, requeue],
   );
 
   // Extract pagination from response

src/frontend/src/pages/System.tsx

@@ -1,5 +1,5 @@
-import { RefreshCw, Server, Activity, Cpu, HardDrive } from 'lucide-react';
+import { RefreshCw, Server, Activity, Cpu, HardDrive, Search } from 'lucide-react';
-import { useSystemStatus, useHealth, useYtDlpStatus, useUpdateYtDlp } from '../api/hooks/useSystem';
+import { useSystemStatus, useHealth, useYtDlpStatus, useUpdateYtDlp, useMissingScanStatus, useTriggerMissingScan } from '../api/hooks/useSystem';
 import { HealthStatus } from '../components/HealthStatus';
 import { SkeletonSystem } from '../components/Skeleton';
 import { formatBytes } from '../utils/format';
@@ -25,6 +25,8 @@ export function SystemPage() {
   const { data: status, isLoading: statusLoading, error: statusError, refetch: refetchStatus } = useSystemStatus();
   const { data: ytdlpStatus, isLoading: ytdlpLoading } = useYtDlpStatus();
   const updateYtDlp = useUpdateYtDlp();
+  const { data: missingScanData } = useMissingScanStatus();
+  const triggerMissingScan = useTriggerMissingScan();
 
   const isLoading = healthLoading || statusLoading;
 
@@ -92,6 +94,102 @@ export function SystemPage() {
         ) : null}
       </section>
 
+      {/* ── Missing File Scan section ── */}
+      <section style={{ marginBottom: 'var(--space-8)' }}>
+        <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', marginBottom: 'var(--space-4)' }}>
+          <h2 style={{ display: 'flex', alignItems: 'center', gap: 'var(--space-2)', fontSize: 'var(--font-size-lg)', fontWeight: 600, color: 'var(--text-primary)' }}>
+            <Search size={18} style={{ color: 'var(--warning)' }} />
+            Missing File Scan
+          </h2>
+          <button
+            onClick={() => triggerMissingScan.mutate()}
+            disabled={triggerMissingScan.isPending}
+            className="btn btn-warning"
+          >
+            {triggerMissingScan.isPending ? (
+              <>
+                <RefreshCw size={14} style={{ animation: 'spin 1s linear infinite' }} />
+                Scanning…
+              </>
+            ) : (
+              <>
+                <Search size={14} />
+                Scan Now
+              </>
+            )}
+          </button>
+        </div>
+
+        <div
+          style={{
+            backgroundColor: 'var(--bg-card)',
+            borderRadius: 'var(--radius-lg)',
+            border: '1px solid var(--border)',
+            padding: 'var(--space-4)',
+          }}
+        >
+          {triggerMissingScan.data && (
+            <div
+              role="status"
+              style={{
+                padding: 'var(--space-3)',
+                marginBottom: 'var(--space-3)',
+                borderRadius: 'var(--radius-md)',
+                backgroundColor: triggerMissingScan.data.data.missing > 0 ? 'var(--warning-bg)' : 'var(--success-bg)',
+                color: triggerMissingScan.data.data.missing > 0 ? 'var(--warning)' : 'var(--success)',
+                fontSize: 'var(--font-size-sm)',
+                fontWeight: 500,
+              }}
+            >
+              Scan complete: checked {triggerMissingScan.data.data.checked} files, found {triggerMissingScan.data.data.missing} missing
+              {' '}({(triggerMissingScan.data.data.duration / 1000).toFixed(1)}s)
+            </div>
+          )}
+
+          {triggerMissingScan.error && (
+            <div
+              role="alert"
+              style={{
+                padding: 'var(--space-3)',
+                marginBottom: 'var(--space-3)',
+                borderRadius: 'var(--radius-md)',
+                backgroundColor: 'var(--danger-bg)',
+                color: 'var(--danger)',
+                fontSize: 'var(--font-size-sm)',
+              }}
+            >
+              Scan failed: {triggerMissingScan.error instanceof Error ? triggerMissingScan.error.message : 'Unknown error'}
+            </div>
+          )}
+
+          {missingScanData?.data ? (
+            <table style={{ width: '100%', borderCollapse: 'collapse' }}>
+              <tbody>
+                <SystemInfoRow
+                  icon={<Activity size={14} style={{ color: 'var(--text-muted)' }} />}
+                  label="Last Scan"
+                  value={new Date(missingScanData.data.lastRun).toLocaleString()}
+                />
+                <SystemInfoRow
+                  icon={<Search size={14} style={{ color: 'var(--info)' }} />}
+                  label="Files Checked"
+                  value={String(missingScanData.data.result.checked)}
+                />
+                <SystemInfoRow
+                  icon={<HardDrive size={14} style={{ color: missingScanData.data.result.missing > 0 ? 'var(--warning)' : 'var(--success)' }} />}
+                  label="Missing Files"
+                  value={String(missingScanData.data.result.missing)}
+                />
+              </tbody>
+            </table>
+          ) : (
+            <p style={{ color: 'var(--text-muted)', fontSize: 'var(--font-size-sm)', margin: 0 }}>
+              No scan has been run yet. Click "Scan Now" to check for missing files.
+            </p>
+          )}
+        </div>
+      </section>
+
       {/* ── System Status section ── */}
       <section>
         <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', marginBottom: 'var(--space-4)' }}>