The 180-degree line (axis of action) runs between the subjects. Keep the camera on one side and screen direction stays readable: A stays left, B stays right. Cross the line and they swap. Audiences feel it as a mistake even when they cannot name it.
On a storyboard, draw the line once on the master and obey it on every over and single. If you *must* cross, board the crossing shot so the cut is motivated (a camera move, a character walk).
Craft: continuity and eyelines · 180-degree rule on a storyboard.
Why generators break it
A model that draws frames independently does not share a floor plan. Humans have to impose geography. AI generators.
Related: eyeline, coverage, over the shoulder.