fix: OG scrape fallback — parse JSON-LD first, fix artist field index

JSON-LD byArtist gives the correct artist list. As secondary fallback,
OG desc format is 'Artist · Song · Year' not 'Song · Artist · Album',
so use desc_parts[0] not desc_parts[1] for artist.
Also handle both attribute orderings in meta tags.

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

backend/spotify_resolve.py

@@ -84,22 +84,48 @@ def resolve(sp_type, sp_id):
             except Exception as e:
                 eprint(f'[spotapi] song_info({arg!r}) failed: {e}')
 
-        # Fallback: scrape Open Graph tags from the public Spotify track page
+        # Fallback: scrape the public Spotify track page
         if not tr:
-            eprint(f'[spotapi] falling back to OG scrape for track {sp_id}')
+            eprint(f'[spotapi] falling back to page scrape for track {sp_id}')
             try:
                 req = urllib.request.Request(url, headers={'User-Agent': 'Mozilla/5.0'})
                 with urllib.request.urlopen(req, timeout=10) as resp:
                     page = resp.read().decode('utf-8', errors='replace')
-                og = {m.group(1): _html.unescape(m.group(2))
-                      for m in re.finditer(r'<meta\s+property="og:([^"]+)"\s+content="([^"]*)"', page)}
-                # og:description format: "Song · Artist · Album · Year"
+
+                track_name, artist_name, album_name, art_url = '', '', '', ''
+
+                # 1) JSON-LD structured data — most reliable, always has byArtist
+                ld_m = re.search(r'<script[^>]+type=["\']application/ld\+json["\'][^>]*>(.*?)</script>', page, re.DOTALL | re.IGNORECASE)
+                if ld_m:
+                    try:
+                        ld = json.loads(ld_m.group(1))
+                        track_name = ld.get('name', '')
+                        by_artist  = ld.get('byArtist', [])
+                        if isinstance(by_artist, list):
+                            artist_name = ', '.join(a.get('name', '') for a in by_artist if a.get('name'))
+                        elif isinstance(by_artist, dict):
+                            artist_name = by_artist.get('name', '')
+                        in_album   = ld.get('inAlbum') or {}
+                        album_name = in_album.get('name', '') if isinstance(in_album, dict) else ''
+                        eprint(f'[spotapi] JSON-LD: name={track_name!r} artist={artist_name!r} album={album_name!r}')
+                    except Exception as e:
+                        eprint(f'[spotapi] JSON-LD parse failed: {e}')
+
+                # 2) OG tags — artist is desc_parts[0], then type ("Song"), then year
+                if not track_name:
+                    og = {}
+                    for m in re.finditer(r'<meta\s+(?:property|name)=["\']og:([^"\']+)["\']\s+content=["\']([^"\']*)["\']', page):
+                        og[m.group(1)] = _html.unescape(m.group(2))
+                    for m in re.finditer(r'<meta\s+content=["\']([^"\']*)["\'][^>]+(?:property|name)=["\']og:([^"\']+)["\']', page):
+                        og[m.group(2)] = _html.unescape(m.group(1))
                     desc_parts = [p.strip() for p in og.get('description', '').split('·')]
                     track_name  = og.get('title', '')
-                artist_name = desc_parts[1] if len(desc_parts) > 1 else ''
-                album_name  = desc_parts[2] if len(desc_parts) > 2 else ''
+                    # Real format: "Artist · Song · Year · N songs." — artist is index 0
+                    artist_name = desc_parts[0] if desc_parts else ''
+                    album_name  = ''
                     art_url     = og.get('image', '')
-                eprint(f'[spotapi] OG scrape: name={track_name!r} artist={artist_name!r} album={album_name!r}')
+                    eprint(f'[spotapi] OG scrape: name={track_name!r} artist={artist_name!r}')
+
                 if track_name:
                     tr = {
                         'trackName':         track_name,
@@ -112,7 +138,7 @@ def resolve(sp_type, sp_id):
                         'durationMs':        None,
                     }
             except Exception as e:
-                eprint(f'[spotapi] OG scrape failed: {e}')
+                eprint(f'[spotapi] page scrape failed: {e}')
 
         if not tr:
             raise Exception(f'Track resolution failed: song_info returned GenericError and OG scrape found no title')