set foldexpr=0
set foldlevelstart=99
set foldlevel=99
+" Indent summaries one level past the retained first line, not a continuation.
+let &foldtext = 'repeat(" ", indent(v:foldstart - 1) + shiftwidth()) . printf("… %d lines …", v:foldend - v:foldstart + 1)'
+set fillchars+=fold:\ " Leave the rest of the summary line blank.
" Interaction and persistence
set mouse=a