Add Jellyfin NFO sidecar generation for downloaded videos

Writes a Kodi/Jellyfin-compatible .nfo XML file next to each .mp4 on
download completion, deletes it when the download record is removed, and
exposes POST /api/downloads/nfo/generate to backfill NFOs for existing
downloads. Frontend adds a "Generate NFO" button in the Downloads header.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/routers/downloads.py

@@ -53,6 +53,32 @@ def _on_progress(download_id: int, pct: float):
         db.close()
 
 
+def _write_nfo(video: Video, channel: Optional[Channel]) -> None:
+    """Write a Jellyfin/Kodi-compatible .nfo sidecar next to the video file."""
+    from pathlib import Path
+    try:
+        nfo_path = Path(settings.download_path) / f"{video.youtube_video_id}.nfo"
+        title = (video.title or "").replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
+        plot = (video.description or "").replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
+        studio = (channel.name if channel else "").replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
+        year = video.published_at.year if video.published_at else ""
+        date = video.published_at.strftime("%Y-%m-%d") if video.published_at else ""
+        thumb_url = f"https://i.ytimg.com/vi/{video.youtube_video_id}/maxresdefault.jpg"
+        nfo_path.write_text(f"""<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<movie>
+  <title>{title}</title>
+  <plot>{plot}</plot>
+  <year>{year}</year>
+  <releasedate>{date}</releasedate>
+  <studio>{studio}</studio>
+  <thumb aspect="poster">{thumb_url}</thumb>
+  <thumb aspect="backdrop">{thumb_url}</thumb>
+  <uniqueid type="youtube" default="true">{video.youtube_video_id}</uniqueid>
+</movie>""", encoding="utf-8")
+    except Exception:
+        pass
+
+
 def _on_complete(download_id: int, file_path: Optional[str], resolution: Optional[str] = None):
     db = SessionLocal()
     try:
@@ -72,6 +98,12 @@ def _on_complete(download_id: int, file_path: Optional[str], resolution: Optiona
             uv.downloaded = True
             uv.downloaded_at = datetime.utcnow()
             db.commit()
+
+            # Write Jellyfin sidecar
+            video = db.query(Video).filter_by(id=dl.video_id).first()
+            if video:
+                channel = db.query(Channel).filter_by(id=video.channel_id).first() if video.channel_id else None
+                _write_nfo(video, channel)
     finally:
         db.close()
 
@@ -294,6 +326,7 @@ def _purge_expired_trash(db: Session):
 
 
 def _delete_download_record(db: Session, dl: "Download", user_id: int):
+    from pathlib import Path
     video = db.query(Video).filter_by(id=dl.video_id).first()
     if video:
         fp = ytdlp.predicted_file_path(video.youtube_video_id)
@@ -302,6 +335,13 @@ def _delete_download_record(db: Session, dl: "Download", user_id: int):
                 os.remove(fp)
             except OSError:
                 pass
+        # Remove NFO sidecar if present
+        nfo = Path(settings.download_path) / f"{video.youtube_video_id}.nfo"
+        if nfo.exists():
+            try:
+                os.remove(nfo)
+            except OSError:
+                pass
         uv = db.query(UserVideo).filter_by(user_id=user_id, video_id=dl.video_id).first()
         if uv:
             uv.downloaded = False
@@ -309,6 +349,38 @@ def _delete_download_record(db: Session, dl: "Download", user_id: int):
     db.delete(dl)
 
 
+@router.post("/nfo/generate", status_code=200)
+def generate_nfo_files(
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """Generate .nfo sidecar files for all completed downloads that have a file on disk."""
+    from pathlib import Path
+    rows = db.execute(
+        text("""
+            SELECT v.id, v.youtube_video_id, v.channel_id
+            FROM downloads d
+            JOIN videos v ON d.video_id = v.id
+            WHERE d.user_id = :uid AND d.status = 'complete'
+        """),
+        {"uid": current_user.id},
+    ).mappings().all()
+
+    written = 0
+    for row in rows:
+        fp = Path(settings.download_path) / f"{row['youtube_video_id']}.mp4"
+        if not fp.exists():
+            continue
+        video = db.query(Video).filter_by(id=row["id"]).first()
+        if not video:
+            continue
+        channel = db.query(Channel).filter_by(id=video.channel_id).first() if video.channel_id else None
+        _write_nfo(video, channel)
+        written += 1
+
+    return {"generated": written}
+
+
 @router.delete("/all", status_code=204)
 def delete_all_downloads(
     db: Session = Depends(get_db),