fix(downloads): harden playlist state and scrolling

src/utils/addDownloadMetadata.test.ts

@@ -293,7 +293,10 @@ describe('add download metadata workflow', () => {
     const existing = row({
       file: 'old-name.zip',
       requestContextVersion: 1,
-      generation: 2
+      generation: 2,
+      size: '10 MB',
+      sizeBytes: 10,
+      resumable: true
     });
 
     const refreshed = reconcileDownloadRows(
@@ -310,7 +313,47 @@ describe('add download metadata workflow', () => {
       file: 'new-name.zip',
       status: 'loading',
       generation: 3,
-      requestContextVersion: 2
+      requestContextVersion: 2,
+      size: undefined,
+      sizeBytes: undefined,
+      resumable: undefined
+    });
+  });
+
+  it('drops stale playlist provenance when an entry remains after its playlist is removed', () => {
+    const videoUrl = 'https://www.youtube.com/watch?v=one';
+    const playlistUrl = 'https://www.youtube.com/playlist?list=PL123';
+    const existing = row({
+      sourceUrl: videoUrl,
+      downloadUrl: videoUrl,
+      file: '001 - First.mp4',
+      status: 'ready',
+      generation: 3,
+      isMedia: true,
+      playlistSourceUrl: playlistUrl,
+      playlistTitle: 'Example playlist',
+      playlistIndex: 1,
+      playlistCount: 2,
+      playlistEntryTitle: 'First',
+      requestContextVersion: 7,
+      size: '10 MB',
+      sizeBytes: 10,
+      resumable: true
+    });
+
+    const rows = reconcileDownloadRows(videoUrl, [existing]);
+
+    expect(rows[0]).toMatchObject({
+      file: 'watch',
+      status: 'loading',
+      generation: 4,
+      isMedia: true,
+      playlistSourceUrl: undefined,
+      playlistIndex: undefined,
+      size: undefined,
+      sizeBytes: undefined,
+      resumable: undefined,
+      requestContextVersion: undefined
     });
   });
 
@@ -425,6 +468,10 @@ describe('add download metadata workflow', () => {
       row({ status: 'metadata-error', selected: false }),
       row({ id: 'ready', status: 'ready' })
     ])).toContain('Ready to add 1 download');
+    expect(metadataSummaryMessage([
+      row({ status: 'metadata-error' }),
+      row({ id: 'skipped', status: 'ready', selected: false })
+    ])).toContain('can still be added');
   });
 
   it('keeps failed media routing without a format selector', () => {

src/utils/addDownloadMetadata.ts

@@ -182,21 +182,39 @@ export const reconcileDownloadRows = (
       const requestContextVersion = input.requestContextVersion;
       const contextChanged = requestContextVersion !== undefined
         && requestContextVersion !== preserved.requestContextVersion;
-      if ((forcedMedia && !preserved.isMedia) || contextChanged) {
+      const playlistContextChanged = preserved.playlistSourceUrl !== input.playlistSourceUrl
+        || preserved.playlistTitle !== input.playlistTitle
+        || preserved.playlistIndex !== input.playlistIndex
+        || preserved.playlistCount !== input.playlistCount
+        || preserved.playlistEntryTitle !== input.playlistEntryTitle;
+      if ((forcedMedia && !preserved.isMedia) || contextChanged || playlistContextChanged) {
         const requestedFilename = input.playlistSourceUrl
           ? `${playlistFilePrefix(input.playlistIndex, input.playlistCount)}${input.playlistEntryTitle || 'video'}`
           : requestFilenames[input.sourceUrl];
         return {
           ...preserved,
-          file: contextChanged
+          file: contextChanged || playlistContextChanged
             ? canonicalizeDownloadFileName(requestedFilename || fileNameFromUrl(input.sourceUrl))
             : preserved.file,
           status: 'loading',
           generation: preserved.generation + 1,
           requestContextVersion,
-          isMedia: preserved.isMedia || forcedMedia,
-          formats: preserved.isMedia || forcedMedia ? undefined : preserved.formats,
-          selectedFormat: preserved.isMedia || forcedMedia ? undefined : preserved.selectedFormat,
+          isMedia: preserved.isMedia || forcedMedia || Boolean(input.playlistSourceUrl),
+          size: undefined,
+          sizeBytes: undefined,
+          resumable: undefined,
+          formats: preserved.isMedia || forcedMedia || Boolean(input.playlistSourceUrl)
+            ? undefined
+            : preserved.formats,
+          selectedFormat: preserved.isMedia || forcedMedia || Boolean(input.playlistSourceUrl)
+            ? undefined
+            : preserved.selectedFormat,
+          isPlaylist: input.isPlaylist,
+          playlistSourceUrl: input.playlistSourceUrl,
+          playlistTitle: input.playlistTitle,
+          playlistIndex: input.playlistIndex,
+          playlistCount: input.playlistCount,
+          playlistEntryTitle: input.playlistEntryTitle,
           playlistError: undefined
         };
       }
@@ -361,7 +379,7 @@ export const metadataSummaryMessage = (rows: AddDownloadDraftRow[]): string => {
   if (failedMedia > 0) {
     return `Media metadata is unavailable for ${failedMedia} item${failedMedia === 1 ? '' : 's'}. Refresh metadata before adding.`;
   }
-  if (failed === rows.length) {
+  if (failed === selectedRows.length) {
     return 'Metadata is unavailable. Downloads can still be added using fallback details.';
   }
   if (failed > 0) {