home: services: Add niri.

This introduces a new home service for Niri, a scrollable tiling Wayland
compositor that combines traditional tiling window management with smooth
scrolling between workspaces.

The service provides:
- home-niri-service-type for installing and configuring Niri
- Shepherd service that starts Niri in a DBus session
- Proper Wayland environment variables (XDG_CURRENT_DESKTOP,
XDG_SESSION_DESKTOP, etc.)
- Integration with xdg-desktop-portal and related components

The service starts Niri with appropriate environment variables for
Wayland compatibility and includes necessary dependencies like
xdg-desktop-portal-gnome and xdg-desktop-portal-gtk for proper
desktop integration.

* gnu/home/services/niri.scm: New file containing the service implementation.
* gnu/local.mk (GNU_SYSTEM_MODULES): Register the new module.
* doc/guix.texi (Niri window manager): Add comprehensive documentation.

Change-Id: I9ef081226b4aaa31706d1fbc0d8b7aa1a202cd6e

3 files changed, 110 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 9109ce4a388..23062498106 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -49888,6 +49888,7 @@ services)}.
 * Mail: Mail Home Services.     Services for managing mail.
 * Messaging: Messaging Home Services.  Services for managing messaging.
 * Media: Media Home Services.   Services for managing media.
+* Niri: Niri window manager.    Setting up the Niri.
 * Sway: Sway window manager.    Setting up the Sway configuration.
 * Networking: Networking Home Services.  Networking services.
 * Miscellaneous: Miscellaneous Home Services.  More services.
@@ -52420,6 +52421,35 @@ object @code{%unset-value} (from @code{(gnu services configuration)}).
 
 @end deffn
 
+@node Niri window manager
+@subsection Niri window manager
+
+@cindex niri, Home Service
+@cindex niri, configuration
+@cindex Wayland compositor
+@cindex scrollable tiling window manager
+The @code{(gnu home services niri)} module provides the
+@code{home-niri-service-type} service, which installs and configures
+@uref{https://github.com/YaLTeR/niri, Niri}, a scrollable tiling Wayland
+compositor. Niri combines traditional tiling window management with
+smooth scrolling between workspaces.
+
+This service starts Niri as a user-level desktop session with proper
+environment variables configured for Wayland compatibility, including
+@code{XDG_CURRENT_DESKTOP}, @code{XDG_SESSION_DESKTOP}, and
+@code{DESKTOP_SESSION}.
+
+Here is a minimal example service declaration for your
+@code{home-environment} configuration:
+
+@example
+(service home-niri-service-type)
+@end example
+
+For more advanced configurations, you can customize the service with a
+@code{niri-configuration} record to specify additional environment
+variables.
+
 @node Sway window manager
 @subsection Sway window manager
 
diff --git a/gnu/home/services/niri.scm b/gnu/home/services/niri.scm
new file mode 100644
index 00000000000..c590b4ca940
--- /dev/null
+++ b/gnu/home/services/niri.scm
@@ -0,0 +1,79 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2025 Oleg Pykhalov <go.wigust@gmail.com>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu home services niri)
+  #:use-module (gnu home services)
+  #:use-module (gnu home services shepherd)
+  #:use-module (gnu packages bash)
+  #:use-module (gnu packages freedesktop)
+  #:use-module (gnu packages glib)
+  #:use-module (gnu packages gnome)
+  #:use-module (gnu packages wm)
+  #:use-module (gnu services)
+  #:use-module (gnu services shepherd)
+  #:use-module (guix gexp)
+  #:use-module (guix records)
+  #:export (niri-configuration
+            home-niri-service-type))
+
+(define-record-type* <niri-configuration>
+  niri-configuration make-niri-configuration
+  niri-configuration?
+  (environment-variables niri-configuration-environment-variables ;list of strings
+                         (default '())))
+
+(define (home-niri-shepherd-service config)
+  "Return a shepherd service that runs Niri, a scrollable tiling Wayland
+compositor.  The service starts Niri in a DBus session with appropriate
+environment variables set for a Wayland desktop session."
+  (list (shepherd-service
+          (documentation "Run Niri scrollable tiling Wayland compositor.")
+          (provision '(niri))
+          (start #~(make-forkexec-constructor
+                    (list #$(file-append bash "/bin/bash") "-l"
+                          "-c" "exec dbus-run-session niri --session")
+                    #:environment-variables
+                    (append (list #$@(niri-configuration-environment-variables config))
+                            '("DESKTOP_SESSION=niri"
+                              "XDG_CURRENT_DESKTOP=niri"
+                              "XDG_SESSION_DESKTOP=niri"
+                              "XDG_SESSION_TYPE=wayland")
+                            (filter (negate
+                                     (lambda (str)
+                                       (string-prefix? "WAYLAND_DISPLAY=" str)))
+                                    (environ)))))
+          (stop #~(make-kill-destructor)))))
+
+(define home-niri-service-type
+  (service-type
+   (name 'home-niri)
+   (extensions
+    (list (service-extension home-shepherd-service-type
+                             home-niri-shepherd-service)
+          (service-extension home-profile-service-type
+                             (lambda (config)
+                               (list dbus
+                                     niri
+                                     xdg-desktop-portal
+                                     xdg-desktop-portal-gnome
+                                     xdg-desktop-portal-gtk)))))
+   (description "Install and configure Niri, a scrollable tiling Wayland
+compositor.  This service starts Niri as a user-level desktop session with
+proper environment variables set for Wayland compatibility.  It ensures Niri
+and its dependencies are available in the user's profile.")
+   (default-value (niri-configuration))))
diff --git a/gnu/local.mk b/gnu/local.mk
index 76f9f173edf..abecf929aa7 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -118,6 +118,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/home/services/messaging.scm		\
   %D%/home/services/mpv.scm     		\
   %D%/home/services/music.scm			\
+  %D%/home/services/niri.scm			\
   %D%/home/services/pm.scm			\
   %D%/home/services/shells.scm			\
   %D%/home/services/shepherd.scm		\