the "feedback zone" in compositor

With the implementation of "simulation zone" in geometry nodes, I propose to adopt the same philosophy and UI for the "feedback zone" in compositor.

The core idea is simple - allow passing image (and other?) data back into a feedback input node to form feedback loops.

Feedback workflow is common in realtime visual software or visual processing, such as things aimed for VJing, or node toolkits like TouchDesigner. While blender might not be aimed for use cases that typically benefit from feedback loops, I figured it might be a nice, natural exchange of everything-nodes ideas between different environments, coupled with other work happening for viewport compositor.

The use-cases are typically NPR focused. At it's simplest it's useful for cheap trail, ghosting effects, but at it's most complex it can generate entirely new animated imagery from scratch, that relies on emergent behavior of consecutive frames.

Here's a mockup, creating a simple turbulent smoke-like effect:

I've created the actual visual with equivalent nodes in TouchDesigner. (Parameters are estimate in blender's mockup)

Side note, this also highlights the painful lack of animatable noise in compositor, as the legacy textures accessible from compositor lack any "seed" or 3rd dimension parameter. docs.blender.org/manual/en/latest/render/materials/legacy_textures/introduction.html ...But that's a story for another proposal. And I heard it's getting an overhaul anyway?