Indeed. Sessions' actions were against all odds; Trump almost certainly was deeply shocked, particularly since it was practically impossible to replace him.
It is easy to conclude no one acts in such outrageous manner and against all expectations unless they are a stealth operative subject to an undisclosed agenda. Perhaps, as you say, after Barr's work is finished a credible author will give us a better view.
Isn’t there a very simple explanation for Sessions “outrageous” behavior? Behavior that put Trump and the country in dire jeopardy? A very simple explanation that doesn’t include Sessions’ use of double secret 4D chess that Trump was necessarily kept completely in the dark about?