The way I implemented caching was flawed. I cached the entire formatted directory, for example:
# this is: -t c6 --pre '%F{magenta}'
__prompt_dir_glob__cache[/tmp/something]='%F{magenta}somet\u2025'
This will break if the user wants the last directory to always be not-truncated.
So, we now cache only the glob that matches, and check prefix/suffix/truncate every time.
The second thing I did was to split ::add_glob out to its own file,
and add a --help for it.
Finally, I also renamed things to use underscores.
While I prefer hyphens in functions,
the P10K API requires segments to be called prompt_$name.
To prevent confusion, I just renamed everything.
I may revert this in the future, though.