On Linux a freshly-built desktop app had no presence in the application
launcher: no Hermes in the KDE/GNOME menu, no icon, nothing to pin. Users
had to hand-write ~/.local/share/applications/hermes.desktop and remember
to reindex the menu caches themselves.
`hermes desktop` now writes that entry itself (best-effort, idempotent,
never blocking a launch), and `hermes uninstall --gui` removes it again.
Both fields that matter are absolute:
- Exec — the launcher runs with a minimal environment and no shell PATH
customizations, so a bare `hermes desktop` silently fails for anyone
whose hermes lives in ~/.local/bin or a venv. We resolve the real binary
via relaunch.resolve_hermes_bin(), falling back to an absolute
interpreter + `-m hermes_cli.main`.
- Icon — an unqualified name only resolves against an indexed icon theme,
which we are not in. The spec allows an absolute path, so we point at
apps/desktop/assets/icon.png in the checkout. No copy is installed: Exec
already depends on that same tree, so a second copy would add bytes and
an uninstall step without surviving anything Exec wouldn't.
Menu-cache refresh is tool-gated — update-desktop-database, then
kbuildsycoca6 or kbuildsycoca5 — each only when the binary is actually on
PATH, because most desktops ship none of them and a missing one is not an
error. The entry is only rewritten when its contents change, so a launch
doesn't churn the caches every run.
Verified on NixOS: the generated entry passes desktop-file-validate, a
real kbuildsycoca6 on PATH is invoked with --noincremental, a real
update-desktop-database writes mimeinfo.cache, absent tools are skipped
cleanly, and removal leaves the checkout's icon untouched.
ethernet