The resolved environment for one process run: the home-derived paths plus a
snapshot of the process environment variables. Built once via
Env::from_process and passed down by reference (or Arc) rather than
re-read on demand.
Home-derived file locations under ~/.purple and ~/.ssh. One place that
knows the on-disk layout; every consumer asks here instead of joining the
home directory itself.
The four categories purple’s files fall into, following the XDG Base
Directory split. Each resolves to its own directory; by default all four
point at the legacy ~/.purple.