Vivid, excruciating detail. No matter how evident you think it is at the time.
Novels, especially your novels, do not write themselves in a day, nor a fortnight; and your brain, as amazing as it is, cannot retain every aha! and what-if? it comes up with and then produce said ahas! and what-ifs? whenever you ask. Certainly not if you ask 4 years after the fact. As is the current case.