cleanup: programs: dont assume sway is always the wayland/x11 provider

hosts/common/programs/pipewire.nix

@@ -177,6 +177,9 @@ in
       ];
       cleanupCommand = ''rm -f "$XDG_RUNTIME_DIR/pulse/{native,pid}"'';
     };
+
+    # bring up sound by default
+    services."sound".partOf = [ "default" ];
   };
 
   # taken from nixos/modules/services/desktops/pipewire/pipewire.nix

hosts/common/programs/sway/default.nix

@@ -4,6 +4,7 @@
 # sway-config docs: `man 5 sway`
 let
   cfg = config.sane.programs.sway;
+  enableXWayland = config.sane.programs.xwayland.enabled;
   wrapSway = configuredSway: let
     swayLauncher = pkgs.writeShellScriptBin "sway" ''
       test -e "$(dirname "$SWAYSOCK")" || \
@@ -66,7 +67,7 @@ let
       # - when xwayland is enabled, KOreader incorrectly chooses the X11 backend
       #   -> slower; blurrier
       # - xwayland uses a small amount of memory (like 30MiB, IIRC?)
-      enableXWayland = config.sane.programs.xwayland.enabled;
+      inherit enableXWayland;
     }).overrideAttrs (upstream: {
       # fix to create SWAYSOCK and WAYLAND_DISPLAY directly in a sandboxable subdirectory:
       # i can't simply move it after creation i think because that would
@@ -221,7 +222,7 @@ in
         mod
         workspace_layout
       ;
-      xwayland = if config.sane.programs.xwayland.enabled then "enable" else "disable";
+      xwayland = if enableXWayland then "enable" else "disable";
     };
 
     env.XDG_CURRENT_DESKTOP = "sway";
@@ -238,7 +239,15 @@ in
 
     services.sway = {
       description = "sway: tiling wayland desktop environment";
-      dependencyOf = [ "graphical-session" ];  #< TODO: should be safe to remove this now
+      partOf = [
+        "wayland"
+      ] ++ lib.optionals enableXWayland [
+        "x11"
+      ];
+      # partOf = lib.mkMerge [
+      #   "wayland"
+      #   (lib.mkIf enableXWayland "x11")
+      # ];
       command = pkgs.writeShellScript "sway-start" ''
         # have to create these directories before launching sway so that they're available in the sandbox
         mkdir -p "$(dirname "$SWAYSOCK")"
@@ -248,8 +257,8 @@ in
       '';
       readiness.waitExists = [ "$SWAYSOCK" "$XDG_RUNTIME_DIR/$WAYLAND_DISPLAY" ];
     };
-    # link the graphical-session into the default target, so sway gets auto-started
-    services.graphical-session.partOf = [ "default" ];
+    # launch all graphical apps by default
+    services."graphical-session".partOf = [ "default" ];
   };
 
   # TODO: this can go elsewhere

modules/programs/default.nix

@@ -223,6 +223,7 @@ let
           acts as noop for root-enabled packages.
           see `sane.users.<user>.services` for options;
         '';
+        # TODO: this `apply` should by moved to where we pass the `services` down to `sane.users`
         apply = lib.mapAttrs (svcName: svcCfg:
           svcCfg // lib.optionalAttrs (builtins.tryEval svcCfg.description).success {
             # ensure service dependencies based on what a service's program whitelists.
@@ -231,9 +232,10 @@ let
             depends = svcCfg.depends
               ++ lib.optionals (svcName != "dbus" && builtins.elem "user" config.sandbox.whitelistDbus) [
               "dbus"
-            ] ++ lib.optionals (svcName != "sway" && (config.sandbox.whitelistWayland || config.sandbox.whitelistX)) [
-              # TODO: i shouldn't assume sway here: factor out a "partOf" like i do for "sound"
-              "sway"
+            ] ++ lib.optionals ((!builtins.elem "wayland" svcCfg.partOf) && config.sandbox.whitelistWayland) [
+              "wayland"
+            ] ++ lib.optionals ((!builtins.elem "x11" svcCfg.partOf) && config.sandbox.whitelistX) [
+              "x11"
             ] ++ lib.optionals ((!builtins.elem "sound" svcCfg.partOf) && config.sandbox.whitelistAudio) [
               "sound"
             ];

modules/users/default.nix

@@ -157,7 +157,7 @@ let
   userModule = let
     nixConfig = config;
   in with lib; types.submodule ({ name, config, ... }: {
-    options = userOptions// {
+    options = userOptions // {
       default = mkOption {
         type = types.bool;
         default = false;
@@ -273,16 +273,26 @@ let
           '')
         ];
 
+        # a few common targets one can depend on or declare a `partOf` to.
+        # for example, a wayland session provider should:
+        # - declare `myService.partOf = [ "wayland" ];`
+        # - and `graphical-session.partOf = [ "default" ];`
         services."default" = {
           description = "service (bundle) which is started by default upon login";
         };
         services."graphical-session" = {
           description = "service (bundle) which is started upon successful graphical login";
-          # partOf = [ "default" ];  #< leave it to the DEs to set this
+          # partOf = [ "default" ];
         };
         services."sound" = {
           description = "service (bundle) which represents functional sound input/output when active";
-          partOf = [ "default" ];
+          # partOf = [ "default" ];
+        };
+        services."wayland" = {
+          description = "service (bundle) which provides a wayland session";
+        };
+        services."x11" = {
+          description = "service (bundle) which provides a x11 session (possibly via xwayland)";
         };
       }
     ];