I've been trying a builder cart, like hinted in the 0.1.11 announcement:

CD("MYPROJ")
LOAD("MYGAME.P8")
EXPORT("MYGAME.HTML")

running the above cart with "-x" pauses a second or two then exits without exporting.

running it without "-x" launches the loaded cart, which is expected
(from the manual: LOAD("GAME2.P8") -- load and run another cart)
isn't that exactly what happens silently with the "-x" option?
I mean, the builder cart gets replaced by the game cart in memory and that's it?