tailscale-systray: add module (#7821)

Added module for official Tailscale systray app

modules/misc/news/2025/09/2025-09-17_07-03-26.nix

@@ -0,0 +1,7 @@
+{
+  time = "2025-09-17T05:03:26+00:00";
+  condition = true;
+  message = ''
+    A new service is available: 'services.tailscale-systray'.
+  '';
+}

modules/services/tailscale-systray.nix

@@ -0,0 +1,47 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  cfg = config.services.tailscale-systray;
+in
+{
+  meta.maintainers = [ lib.maintainers.yethal ];
+
+  options.services.tailscale-systray = {
+    enable = lib.mkEnableOption "Official Tailscale systray application for Linux";
+
+    package = lib.mkPackageOption pkgs "tailscale" { };
+  };
+
+  config = lib.mkIf cfg.enable {
+    assertions = [
+      (lib.hm.assertions.assertPlatform "services.tailscale-systray" pkgs lib.platforms.linux)
+      {
+        assertion = lib.versionAtLeast cfg.package.version "1.88.1";
+        message = ''
+          Tailscale systray is available since version 1.88.1
+        '';
+      }
+    ];
+
+    systemd.user.services.tailscale-systray = {
+      Unit = {
+        Description = "Official Tailscale systray application for Linux";
+        Requires = [ "tray.target" ];
+        After = [
+          "graphical-session.target"
+          "tray.target"
+        ];
+        PartOf = [ "graphical-session.target" ];
+      };
+      Install = {
+        WantedBy = [ "graphical-session.target" ];
+      };
+      Service.ExecStart = "${lib.getExe cfg.package} systray";
+    };
+  };
+}

tests/modules/services/tailscale-systray/basic.nix

@@ -0,0 +1,18 @@
+{ config, ... }:
+{
+  services.tailscale-systray = {
+    enable = true;
+    package = config.lib.test.mkStubPackage {
+      name = "tailscale";
+      version = "1.88.1";
+      outPath = "@tailscale@";
+    };
+  };
+
+  nmt.script = ''
+    serviceFile=home-files/.config/systemd/user/tailscale-systray.service
+    assertFileExists $serviceFile
+    assertFileRegex $serviceFile \
+      '^ExecStart=@tailscale@/bin/tailscale systray$'
+  '';
+}

tests/modules/services/tailscale-systray/default.nix

@@ -0,0 +1,5 @@
+{ lib, pkgs, ... }:
+
+lib.optionalAttrs pkgs.stdenv.hostPlatform.isLinux {
+  tailscale-systray-basic = ./basic.nix;
+}