When I lived in the SF bay area caapi did OK outside in a protected area in the summer i.e., next to a south facing wall and under lattice semi-shade. In the winter they needed a heated GH. When they are small like yours they are definitely more sensitive to cold and mortality rates are much higher.
I'm in Florida now and I am able to keep one in the ground, although it can and has frozen to the ground on several occasions. This is a 20 year old plant, so don't try this at home.
I'd keep yours inside till it gains some mass and then put outside only when it warms up considerably.
I already asked Alice.