home/fuji: add river wm

fuji/configuration.nix

@@ -8,6 +8,19 @@
 }:
 let
   USER = "akill";
+
+  river-session = pkgs.runCommand "river-session"
+    { passthru.providedSessions = [ "river" ]; }
+    ''
+      install -Dm444 ${pkgs.writeText "river.desktop" ''
+        [Desktop Entry]
+        Name=River
+        Comment=A non-monolithic Wayland compositor
+        Exec=${lib.getExe pkgs.river}
+        Type=Application
+        DesktopNames=river
+      ''} $out/share/wayland-sessions/river.desktop
+    '';
 in
 {
   imports = [ ./wireguard.nix ];
@@ -206,6 +219,7 @@ in
     systemPackages = with pkgs; [
       maliit-keyboard
       android-tools
+      river
     ];
 
     sessionVariables = {
@@ -242,7 +256,6 @@ in
       enable = true;
       enableSSHSupport = true;
     };
-    hyprland.enable = true;
     steam = {
       enable = true;
       remotePlay.openFirewall = true;
@@ -262,6 +275,7 @@ in
   xdg.portal = {
     enable = true;
     wlr.enable = true;
+    config.river.default = [ "wlr" "gtk" ];
   };
 
   documentation.dev.enable = true;
@@ -318,6 +332,8 @@ in
     upower.enable = lib.mkForce false;
     userborn.enable = true;
 
+    displayManager.sessionPackages = [ river-session ];
+
     greetd = {
       enable = true;
       settings = {
@@ -328,6 +344,7 @@ in
               --remember \
               --remember-session \
               --greeting 'Welcome to NixOS' \
+              --sessions ${config.services.displayManager.sessionData.desktops}/share/wayland-sessions \
               --cmd sway
           '';
           user = "greeter";

home/common/river.nix

@@ -0,0 +1,111 @@
+{ pkgs
+, inputs
+, system
+, lib
+, ...
+}:
+let
+  quickshell_bar = inputs.quickshell_bar.packages.${system}.default;
+  att_wm = inputs.att_wm.packages.${system}.default;
+
+  cliphist_river = pkgs.writeShellScriptBin "cliphist_river" ''
+    ${lib.getExe pkgs.cliphist} list | \
+    ${lib.getExe pkgs.wofi} --dmenu --insensitive | \
+    ${lib.getExe pkgs.cliphist} decode | \
+    ${pkgs.wl-clipboard}/bin/wl-copy
+  '';
+
+  screenshot_clip = pkgs.writeShellScriptBin "screenshot_clip" ''
+    GEOM="$(${lib.getExe pkgs.slurp} -d)"
+    ${lib.getExe pkgs.grim} -g "$GEOM" - | ${pkgs.wl-clipboard}/bin/wl-copy
+  '';
+in
+{
+  # att_wm is configured at compile time, dwm-style — there is no config file to
+  # generate here, and the bindings live in its own src/config.zig (Alt as mod,
+  # nine tags, master/monocle/tabbed). To override them without forking, build
+  # with a replacement config:
+  #   inputs.att_wm.packages.${system}.default.override { configFile = ./config.zig; }
+  #
+  # It spawns `foot` and `wmenu-run` by bare name, so both have to be on PATH;
+  # cliphist_river and screenshot_clip are here for a future config.zig to spawn
+  # the same way. The package also carries att_wmctl, the CLI that drives the
+  # window manager over its IPC socket.
+  home.packages = [
+    att_wm
+    pkgs.wmenu
+    cliphist_river
+    screenshot_clip
+  ];
+
+  # river runs $XDG_CONFIG_HOME/river/init at startup if it is executable, and
+  # that is the whole of river's configuration surface — it implements no
+  # window management itself, that is att_wm over river-window-management-v1.
+  xdg.configFile."river/init" = {
+    executable = true;
+    text = ''
+      #!${pkgs.runtimeShell}
+
+      # greetd discards the session's stdio, and river/att_wm log to stderr only
+      # — without this a failing window manager is a silent blank screen.
+      log="''${XDG_STATE_HOME:-$HOME/.local/state}/river.log"
+      mkdir -p "$(dirname "$log")"
+      exec >>"$log" 2>&1
+      echo "=== river init $(date -Is) ==="
+
+      # river's session file sets no DesktopNames, so the portal backend
+      # (xdg.portal.config.river in fuji/configuration.nix) needs this.
+      export XDG_CURRENT_DESKTOP=river
+      export XDG_SESSION_TYPE=wayland
+
+      # Hand the session env to systemd/D-Bus, then bring up the target the
+      # user services hang off — same dance the home-manager sway module does.
+      ${pkgs.dbus}/bin/dbus-update-activation-environment --systemd \
+        DISPLAY WAYLAND_DISPLAY XDG_CURRENT_DESKTOP XDG_SESSION_TYPE \
+        NIXOS_OZONE_WL XCURSOR_THEME XCURSOR_SIZE
+      systemctl --user reset-failed
+      systemctl --user start river-session.target
+
+
+      # The bar (same one sway and hyprland use) picks its backend from the
+      # environment alone: with no $HYPRLAND_INSTANCE_SIGNATURE and no
+      # $SWAYSOCK/$I3SOCK it falls through to att_wm, so nothing needs setting
+      # here. It retries the connection every second, which is why starting it
+      # before att_wm is fine — and why it must start after river exported
+      # WAYLAND_DISPLAY, since that name is part of the socket path. Both sides
+      # derive $XDG_RUNTIME_DIR/att_wm-$WAYLAND_DISPLAY.sock independently, so
+      # nothing here has to agree on it.
+      ${quickshell_bar}/bin/quickshell-bar &
+      bar=$!
+
+      # att_wm comes from the flake input (git.project-cloud.net/asmir/att_wm),
+      # so the session runs exactly the revision flake.lock pins. Iterating on
+      # it now means `nix flake update att_wm` + rebuild; to test a working tree
+      # without that, run it under a nested river via the repo's run-nested.sh.
+      #
+      # Not exec'd: when att_wm exits we still want to tear the target down.
+      # att_wm's Alt+Ctrl+Shift+q (exit_session) ends river itself.
+      echo "starting ${lib.getExe att_wm}"
+      ${lib.getExe att_wm}
+      echo "=== att_wm exited with $? at $(date -Is) ==="
+
+      # The bar is a child of this script rather than of att_wm, so it outlives
+      # it: reap it here so an att_wm exit doesn't leave a bar floating over a
+      # session with no window manager.
+      kill "$bar" 2>/dev/null || true
+
+      systemctl --user stop river-session.target
+    '';
+  };
+
+
+  systemd.user.targets.river-session = {
+    Unit = {
+      Description = "river compositor session";
+      Documentation = [ "man:systemd.special(7)" ];
+      BindsTo = [ "graphical-session.target" ];
+      Wants = [ "graphical-session-pre.target" ];
+      After = [ "graphical-session-pre.target" ];
+    };
+  };
+}

home/fuji/home.nix

@@ -1,6 +1,8 @@
 { config
 , lib
 , pkgs
+, inputs
+, system
 , ...
 }:
 let
@@ -13,6 +15,7 @@ in
     ../common/zsh.nix
     ../common/i3status-rust.nix
     ../common/sway.nix
+    ../common/river.nix
     ../common/i3.nix
     ./home_packages.nix
     ../common/whatsapp-for-linux.nix
@@ -69,7 +72,6 @@ in
 
   wayland.windowManager = {
     sway.enable = true;
-    hyprland.enable = false;
   };
 
   programs = {