The direction at segment boundaries used by offset-rotate came up during discussion about the SVG pathAngleAtLength() function. I’m opening this issue to get more feedback.

The direction at segment boundaries can be either the direction of the previous path segment or the direction of the next path segment.

Animation software seems to use either of them. After Effects seems to use the direction of the previous path segment. Apple Motion seems to use the direction of the next path segment.

CSS Motion Path defines the direction to be the direction of the previous path segment and Google Chrome has implemented it that way.

Should it be changed to be the direction of the next path segment?

SVG 2 Path Directionality defines the direction at the start of a path segment and the direction at the end of a path segment. CSS Motion Path could be changed to reference either of them to get a more precise definition which covers also zero-length subpaths.