For exporting a mirrored playlist back to Spotify:
- The OAuth scope string was duplicated verbatim in 5 places (spotify_client, the per-profile
registry, and 3 web_server callbacks) — a drift hazard where the authorize URL and token
exchange could request different scopes and silently re-prompt/deny. Extracted ONE
SPOTIFY_OAUTH_SCOPE constant and pointed all 5 at it, and added playlist-modify-public/private
there. Existing users re-auth once to grant write; reads are unaffected.
- SpotifyClient.create_or_update_playlist(name, track_ids, existing_id=None): creates a playlist
owned by the authed user, or replaces an existing one's tracks in place (idempotent re-export).
Chunks at Spotify's 100-track cap. A pre-scope token gets a clear "reconnect Spotify" message
instead of a raw 403. Returns {success, playlist_id, url, added, error}.
6 tests: create-new adds tracks, update replaces (no create), >100 chunking, empty → error (no API
calls), not-authed → error, insufficient-scope → reconnect message. 268 spotify/oauth tests green,
ruff clean. Additive — read paths and existing tokens unchanged.
Next: Deezer write via the ARL gw-light gateway, then the export-job branch + endpoint + modal.