Update app

app/models.py

@@ -93,6 +93,21 @@ class Display(db.Model):
     assigned_playlist_id = db.Column(db.Integer, db.ForeignKey("playlist.id"), nullable=True)
     assigned_playlist = db.relationship("Playlist")
 
+    # Multi-playlist support (active playlists per display).
+    # If a display has any rows in display_playlist, those are used by the player.
+    # If not, we fall back to assigned_playlist_id for backwards compatibility.
+    display_playlists = db.relationship(
+        "DisplayPlaylist",
+        back_populates="display",
+        cascade="all, delete-orphan",
+    )
+    playlists = db.relationship(
+        "Playlist",
+        secondary="display_playlist",
+        viewonly=True,
+        order_by="Playlist.name.asc()",
+    )
+
     created_at = db.Column(db.DateTime, default=datetime.utcnow, nullable=False)
 
     company = db.relationship("Company", back_populates="displays")
@@ -117,6 +132,32 @@ class DisplaySession(db.Model):
     __table_args__ = (db.UniqueConstraint("display_id", "sid", name="uq_display_session_display_sid"),)
 
 
+class DisplayPlaylist(db.Model):
+    """Association table: which playlists are active on a display."""
+
+    # NOTE: Some existing databases include an `id` INTEGER PRIMARY KEY column and a
+    # NOT NULL `position` column on display_playlist. We keep the mapper primary key as
+    # (display_id, playlist_id) for portability, while allowing an optional `id` column
+    # to exist in the underlying table.
+    id = db.Column(db.Integer, nullable=True)
+
+    # Composite mapper PK ensures uniqueness per display.
+    display_id = db.Column(db.Integer, db.ForeignKey("display.id"), primary_key=True)
+    playlist_id = db.Column(db.Integer, db.ForeignKey("playlist.id"), primary_key=True)
+
+    # Ordering of playlists within a display.
+    position = db.Column(db.Integer, default=1, nullable=False)
+
+    created_at = db.Column(db.DateTime, default=datetime.utcnow, nullable=False)
+
+    display = db.relationship("Display", back_populates="display_playlists")
+    playlist = db.relationship("Playlist")
+
+    __table_args__ = (
+        db.UniqueConstraint("display_id", "playlist_id", name="uq_display_playlist_display_playlist"),
+    )
+
+
 class AppSettings(db.Model):
     """Singleton-ish app-wide settings.