feat: add retry functionality for failed downloads

ui/src/app/app.spec.ts

@@ -19,6 +19,7 @@ class DownloadsServiceStub {
   customDirsChanged = new Subject<Record<string, string[]>>();
   ytdlOptionsChanged = new Subject<Record<string, unknown>>();
   updated = new Subject<void>();
+  retryCalls: string[] = [];
 
   getCookieStatus() {
     return of({ status: 'ok', has_cookies: false });
@@ -32,6 +33,11 @@ class DownloadsServiceStub {
     return of({ status: 'ok' as const });
   }
 
+  retry(id: string) {
+    this.retryCalls.push(id);
+    return of({ status: 'ok' as const });
+  }
+
   cancelAdd() {
     return of({ status: 'ok' as const });
   }
@@ -269,6 +275,33 @@ describe('App', () => {
     expect(payload.clipEnd).toBe('1:20');
   });
 
+  it('retries a failed download by its server-side queue id', () => {
+    const fixture = TestBed.createComponent(App);
+    const app = fixture.componentInstance;
+    const download = {
+      id: 'vid1',
+      title: 'Test Video',
+      url: 'https://example.com/v',
+      download_type: 'video',
+      quality: 'best',
+      format: 'any',
+      folder: '',
+      custom_name_prefix: '',
+      playlist_item_limit: 0,
+      status: 'error',
+      msg: 'temporary failure',
+      percent: 0,
+      speed: 0,
+      eta: 0,
+      filename: '',
+      checked: false,
+    };
+
+    app.retryDownload(download.url, download);
+
+    expect(downloads.retryCalls).toEqual([download.url]);
+  });
+
   it('blocks subscribe with invalid title regex', () => {
     const toasts = TestBed.inject(ToastService);
     const errorSpy = vi.spyOn(toasts, 'error').mockImplementation(() => undefined);

ui/src/app/app.ts

@@ -1146,30 +1146,9 @@ export class App implements AfterViewInit, OnInit, OnDestroy {
   }
 
   retryDownload(key: string, download: Download) {
-    const payload = this.buildAddPayload({
-      url: download.url,
-      downloadType: download.download_type,
-      codec: download.codec,
-      quality: download.quality,
-      format: download.format,
-      folder: download.folder,
-      customNamePrefix: download.custom_name_prefix,
-      playlistItemLimit: download.playlist_item_limit,
-      autoStart: true,
-      splitByChapters: download.split_by_chapters,
-      chapterTemplate: download.chapter_template,
-      subtitleLanguage: download.subtitle_language,
-      subtitleMode: download.subtitle_mode,
-      ytdlOptionsPresets: download.ytdl_options_presets?.length
-        ? [...download.ytdl_options_presets]
-        : [],
-      ytdlOptionsOverrides: download.ytdl_options_overrides ? JSON.stringify(download.ytdl_options_overrides) : '',
-      clipStart: download.clip_start != null ? String(download.clip_start) : '',
-      clipEnd: download.clip_end != null ? String(download.clip_end) : '',
-    });
     // Only remove the done-list record once the retry is confirmed queued —
     // deleting it eagerly would silently lose history if the re-add fails.
-    this.downloads.add(payload)
+    this.downloads.retry(key)
       .pipe(takeUntilDestroyed(this.destroyRef))
       .subscribe((status: Status) => {
         if (status.status === 'error') {

ui/src/app/services/downloads.service.spec.ts

@@ -117,6 +117,14 @@ describe('DownloadsService', () => {
     req.flush({ presets: ['Preset A'] });
   });
 
+  it('retry() posts the failed download id', () => {
+    service.retry('https://example.com/v').subscribe();
+    const req = httpMock.expectOne('retry');
+    expect(req.request.method).toBe('POST');
+    expect(req.request.body).toEqual({ ids: ['https://example.com/v'] });
+    req.flush({ status: 'ok' });
+  });
+
   it('cancelAdd posts to cancel-add', () => {
     service.cancelAdd().subscribe();
     const req = httpMock.expectOne('cancel-add');

ui/src/app/services/downloads.service.ts

@@ -169,6 +169,12 @@ export class DownloadsService {
     );
   }
 
+  public retry(id: string) {
+    return this.http.post<Status>('retry', { ids: [id] }).pipe(
+      catchError(this.handleHTTPError)
+    );
+  }
+
   public startById(ids: string[]) {
     return this.http.post<Status>('start', {ids: ids}).pipe(
       catchError(this.handleHTTPError)