presenter.remove_background was accepted and then warned about: the one field
of the compose contract with nothing behind it. A pip bubble that is a circle
of someone's kitchen reads as a sticker; the same bubble with the person cut
out reads as a presenter.

The mask is the whole feature -- it replaces the bubble's shape mask, so
composite_pip needed one line and composite_split needed the B-roll behind the
person's half. Two engines: a TorchScript matting model (an RVM export is the
obvious one, and being recurrent it is steadier over time) when
CODERAI_MATTING_MODEL names one, else torchvision's DeepLabV3, which is
already in the stack and needs no configuration. It borrows the GPU under the
same lease lip-sync takes and is dropped as soon as the scene's mask is
written -- a 100 MB segmenter is not something the manager should have to
evict.

Nothing about it is fatal: a scene that cannot be cut out still gets its
presenter, filmed room and all, and says so in the warnings.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014T3rZnLhydX9QqUcfBbqLu