Purple barrier
Purple barriers, also called purple gates or energy walls, are surfaces that cause the player to drop any held items and terminate any in-progress recording or playback. However, it is possible to teleport through a purple barrier without dropping items. Purple barriers do not stop lasers (but blue ones do).
Every puzzle has a purple barrier at its entrance. Immediately after entering a puzzle through this barrier, the name of the puzzle appears on screen (this generally does not occur when entering a puzzle by climbing over a wall or using a glitch).