0.6.3: Parse Spotify's renamed /items response shape (new apps get item, not track)

Spotify's February 2026 changes did not just move /playlists/{id}/tracks to
/items: for apps on the new behavior the per-entry payload key was renamed
from "track" to "item" (tracks.tracks.track -> items.items.item). Extended
Quota Mode (grandfathered) apps keep the old key, which is why this never
reproduced locally. Every parser in alembic read only "track", so on a new
app each entry looked like a null/local track and was silently skipped: the
CSV came out header-only, sldl no-opped with exit 0, and the playlist page
showed an empty tracklist. Confirmed live on a new app against a playlist
the connected account owns.

All /items consumers (spotify_client.py, spotify-playlist-csv.py,
spotify-retag.py) now parse both key names, and the fields query filter is
gone: it selects by key name, so filtering on track(...) is itself what
returned empty pages on the renamed shape.

Also per the migration guide, new apps only receive playlist contents for
playlists the connected account owns or collaborates on; other playlists
return metadata with no items field at all (public is no longer enough).
That case now raises a pointed error (UI and CSV fetch) instead of reading
as an empty playlist, run-playlist.sh logs the fetched track count and warns
loudly when it is zero, and the README guidance is updated to match.

New tests pin get_playlist_tracks against both response shapes, the
metadata-only error, and pagination.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

pipeline/lib/spotify-playlist-csv.py

@@ -45,10 +45,12 @@ def fetch_playlist(url: str, token: str) -> list[dict]:
         sys.exit(f"Could not parse playlist ID from {url!r}")
     pid = m.group(1)
     tracks = []
-    next_url = (
-        f"{API}/playlists/{pid}/items"
-        "?limit=100&fields=items(track(name,artists(name),album(name),duration_ms,is_local)),next"
-    )
+    # No `fields` filter: Spotify's February 2026 changes renamed each entry's
+    # payload from "track" to "item" for apps on the new behavior (extended
+    # quota / grandfathered apps keep "track"), and a fields filter selects by
+    # key name -- filtering on track(...) silently returns EMPTY pages on the
+    # renamed shape. Fetch unfiltered and parse both key names below.
+    next_url = f"{API}/playlists/{pid}/items?limit=100"
     while next_url:
         req = urllib.request.Request(next_url, headers={"Authorization": f"Bearer {token}"})
         try:
@@ -56,18 +58,26 @@ def fetch_playlist(url: str, token: str) -> list[dict]:
                 data = json.loads(r.read())
         except urllib.error.HTTPError as e:
             if e.code in (403, 404):
-                # The one non-bug cause of this: OAuth playlist reads are
-                # scoped to what the CONNECTED account can see (its own
-                # playlists, collaborations, or ones marked Public).
                 sys.exit(
                     f"Spotify returned {e.code} loading this playlist. The connected "
-                    "Spotify account can't see it: make sure it's owned by, or "
-                    "shared/followed by, whichever account is connected via "
-                    "/connect/spotify, or set it to Public on Spotify."
+                    "Spotify account can't see it: it must own the playlist, be a "
+                    "collaborator on it, or (for grandfathered apps) the playlist "
+                    "must be Public. Check which account is connected via "
+                    "/connect/spotify."
                 )
             raise
-        for item in data.get("items", []):
-            t = item.get("track")
+        if "items" not in data:
+            # New-behavior apps get metadata only (no items field) for
+            # playlists the connected account doesn't own or collaborate on.
+            sys.exit(
+                "Spotify returned this playlist without its contents. For newly "
+                "created Spotify apps, the connected account must OWN the playlist "
+                "or be a collaborator on it (public is no longer enough). Ask the "
+                "owner to make it collaborative and add you, or recreate the "
+                "playlist under the connected account."
+            )
+        for item in data["items"]:
+            t = item.get("track") or item.get("item")
             if not t or t.get("is_local"):
                 continue
             # All artists, comma-joined -- matches what sldl's own Spotify

pipeline/lib/spotify-retag.py

@@ -56,8 +56,11 @@ def fetch_playlist(url: str, token: str) -> list[dict]:
         )
         with urllib.request.urlopen(req, timeout=15) as r:
             data = json.loads(r.read())
-        for item in data["items"]:
-            t = item.get("track")
+        # Entries carry "track" (grandfathered apps) or "item" (apps on the
+        # February 2026 renamed shape); items is absent entirely when the
+        # connected account can't read the playlist's contents.
+        for item in data.get("items", []):
+            t = item.get("track") or item.get("item")
             if not t or t.get("is_local"):
                 continue
             tracks.append(