Bug#1050798: plasma-workspace: please provide a kde-portals.conf for xdg-desktop-portal

[Simon McVittie <smcv@debian.org>]

Source: plasma-workspace
Severity: normal
Tags: trixie sid
User: xdg-desktop-portal@packages.debian.org
Usertags: portals.conf
Control: affects -1 plasma-mobile

xdg-desktop-portal 1.17.x (currently in experimental) introduces a new
way to select which portals will be used for which desktop environments,
modelled on mimeapps.list:

- each desktop environment should provide a file like
  /usr/share/xdg-desktop-portal/kde-portals.conf

- the filename is ${DESKTOP}-portals.conf where ${DESKTOP} is the desktop
  environment's entry in $XDG_CURRENT_DESKTOP (the same as the DesktopNames
  from /usr/share/{x,wayland-}sessions/*.desktop), folded to lower case

- sysadmins and users can override this via files named portals.conf or
  ${DESKTOP}-portals.conf in various locations like /etc/xdg-desktop-portal
  and ~/.config/xdg-desktop-portal

Please see portals.conf(5) or its source code
https://github.com/flatpak/xdg-desktop-portal/blob/main/doc/portals-conf.rst
for full details of the search mechanism.

As a backwards-compatibility mechanism, x-d-p will fall back to trying
to guess the most appropriate portals from the portals' UseIn= fields,
but it will log warnings when it does that. Please add a kde-portals.conf
to tell x-d-p more explicitly what backends Plasma is meant to be using
by default, and test with x-d-p from experimental to check that it's
working as expected.
https://salsa.debian.org/gnome-team/gnome-session/-/commit/b201c9c40e3adc7bf0b1c3504bef4c8602aac31d
is an example of the equivalent change in GNOME.

In KDE's case, it looks as though plasma-workspace and plasma-mobile share
the DesktopNames=KDE name but plasma-mobile depends on plasma-workspace,
so kde-portals.conf can probably be in plasma-workspace without any
further changes required in plasma-mobile?

I believe the file contents can be as simple as this (untested):

[preferred]
default=kde;

plasma-workspace (and plasma-mobile?) should probably have at least a
Recommends on xdg-desktop-portal-kde for this (see also #1019918).

Thanks,
    smcv

-- 
This is part of a mass bug filing:
https://lists.debian.org/debian-devel/2023/08/msg00311.html