[ThorSPB]

What

Playlist and Mix links download one video. A Mix link shared from the YouTube app (playlist?list=RD<id>&playnext=1) left the app on "Starting download..." forever, reported from the church PC on 2026-10-24. yt-dlp took it as a whole playlist, and a Mix never ends. download_video now reduces every YouTube playlist link to one video:

• v= / youtu.be/<id>: that video, with the list dropped
• a Mix (list=RD<id>, YouTube Music RDAMVM<id>): the video it is named after, with no network lookup
• a playlist that names no video: its first entry, from one flat playlist_items=1 lookup; an unreadable playlist is an error, not a hang
• non-YouTube links and links without a list are unchanged

Cancel button (option A of the UI mockups the operator approved). While a manual download runs, its row's Download button becomes a red ✕ Cancel (Others row) or ✕ Cancel download (channel rows).

• Pressing it frees the row at once and shows "Download cancelled."
• download_video(cancel_event=...) stops at the next progress or postprocessor event, skips the player-client retry, and returns DOWNLOAD_CANCELLED.
• It deletes only the files that run wrote: files new since it started and named after its video, such as .part, a finished video-only stream, .temp.mp4 or the pre-mp3 .webm. Anything already in the folder, and other downloads' files, stay.
• Hosted override files stop and drop their .part file.
• A new download on the same row first waits for the cancelled one to finish cleaning up, so the two never write the same files.

Verified

• pytest: 340 passed. New tests cover link reduction, first-entry lookup, an unreadable playlist, cancel mid-download (only that run's files go, no retry), cancel before start, hosted-file cancel, the button toggle, a silent cancelled worker, a stale worker leaving a newer download alone, and a restart waiting for cleanup.
• Live, against YouTube, from the Pi:
  • The reported Mix link downloaded only "Jertfa Ta Pe Golgota-Negativ" (4.17 MiB) in about 4 s. The mp3 conversion then failed only because the Pi has no ffmpeg; the release bundles it.
  • A real download cancelled at 2.0 of 9.7 MB stopped within a second. Its .part was deleted, a pre-existing file was kept, and there was no retry.
• The real GUI code was rendered under Xvfb in the downloading and cancelled states, and it matches the approved mockup.

Not covered: automatic (Fri/Sat) downloads have no row button, so they can't be cancelled.

🤖 Generated with Claude Code