Despite me saying that RefitTrim is dead on arrival due to the extremely narrow way it’s implemented, I actually found my first use case for it today!
However, what did it do with the result? It flipped it… 
McNeel really doesn’t build its tools to play well with any potential future history improvements, do they?
Hello- thanks, the developer is looking at this.
https://mcneel.myjetbrains.com/youtrack/issue/RH-74977
-Pascal
I checked in a fix for this and it should be in future builds.
Regarding the desire to be able to handle trim curves that don’t cut across the entire surface, we have discussed this at length and there are significant issues. I will look at this again for Rhino 9, but there are real problems and a tremendous number of special cases that have to be worked out. Thanks for your input. I will put it on my list: https://mcneel.myjetbrains.com/youtrack/issue/RH-75219/Make-RefitTrim-able-to-handle-chained-and-incomplete-trim-curves
