From 27409eb5fab67f244bfe97bf1565f1ab22942403 Mon Sep 17 00:00:00 2001
From: Alexander <alexander0derevianko@gmail.com>
Date: Fri, 3 Jul 2026 17:31:31 +0200
Subject: [PATCH] Migrate to hm managed theme switch

---
 flake.nix                               |  1 -
 hm-modules/theme/default.nix            | 70 +++++++++++++++++++---
 hm-modules/theme/theme-switch.sh        | 77 +++++++++++++++++++++++++
 machines/fujin/main/default.nix         | 33 ++---------
 machines/fujin/main/home.nix            | 28 ++++++++-
 modules/default.nix                     |  1 -
 modules/theme/default.nix               | 65 ---------------------
 modules/window-manager/hypr/default.nix | 26 ---------
 8 files changed, 168 insertions(+), 133 deletions(-)
 create mode 100644 hm-modules/theme/theme-switch.sh
 delete mode 100644 modules/theme/default.nix

diff --git a/flake.nix b/flake.nix
index 02bb2a6..225531f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -199,7 +199,6 @@
           # Applications
           inputs.copyparty.nixosModules.default
           inputs.vscode-server.nixosModules.default
-          inputs.stylix.nixosModules.stylix
           inputs.nix-ld.nixosModules.nix-ld
           inputs.minegrub-theme.nixosModules.default
           inputs.backlog.nixosModules.default
diff --git a/hm-modules/theme/default.nix b/hm-modules/theme/default.nix
index e3c8ea0..d83ea7a 100644
--- a/hm-modules/theme/default.nix
+++ b/hm-modules/theme/default.nix
@@ -1,4 +1,4 @@
-{ config, lib, pkgs, ... }:
+{ config, lib, pkgs, options, ... }:
 
 with lib;
 
@@ -18,6 +18,35 @@ let
     };
   };
 
+  # Generate all theme-variant combinations
+  themeVariants = concatMapAttrs (name: theme: {
+    "${name}-dark" = { scheme = theme.dark; polarity = "dark"; };
+    "${name}-light" = { scheme = theme.light; polarity = "light"; };
+  }) cfg.themes;
+
+  # Base is gruvbox-dark, everything else is a specialisation
+  baseVariant = "gruvbox-dark";
+  specialisationVariants = filterAttrs (name: _: name != baseVariant) themeVariants;
+
+  availableVariants = concatStringsSep " " (attrNames themeVariants);
+
+  # Userspace theme switcher: activates a pre-built Home Manager
+  # specialisation generation. No sudo, no OS rebuild — just runs the
+  # specialisation's activation script in the base HM generation.
+  #
+  # The script logic lives in ./theme-switch.sh (plain shell, no Nix
+  # escaping); we only inject the two config-derived values it needs.
+  theme-switch = pkgs.writeShellScriptBin "theme-switch" ''
+    baseVariant="${baseVariant}"
+    availableVariants="${availableVariants}"
+    ${builtins.readFile ./theme-switch.sh}
+  '';
+
+  # Stylix is only declared on hosts that import its Home Manager module
+  # (e.g. `fujin`). Servers (susano, izanagi, amaterasu, ...) don't, so
+  # `stylix` isn't declared there. We probe option *declarations* (not
+  # config values) to avoid an evaluation cycle.
+  hasStylix = options ? stylix;
 in {
   options.dov.dynamic-theme = {
     enable = mkEnableOption "dynamic theme switching";
@@ -40,12 +69,35 @@ in {
     };
   };
 
-  config = mkIf cfg.enable {
-    # HM-level stylix config inherits from NixOS level
-    # Specialisations are handled by NixOS module
-    stylix = {
-      enable = true;
-      autoEnable = true;
-    };
-  };
+  config = mkIf cfg.enable (
+    {
+      home.packages = [ theme-switch ];
+    }
+    # Only reference the `stylix` option where it is actually declared.
+    # `mkIf false` is NOT enough: the module system still rejects a
+    # definition (even a disabled one) for an option that does not exist,
+    # which breaks every host that doesn't import stylix. `optionalAttrs`
+    # removes the key structurally, so non-stylix hosts evaluate cleanly.
+    // optionalAttrs hasStylix {
+      stylix = {
+        enable = true;
+        autoEnable = true;
+        # Base scheme/polarity; overridable per specialisation below.
+        base16Scheme = mkDefault themeVariants.${baseVariant}.scheme;
+        polarity = mkDefault themeVariants.${baseVariant}.polarity;
+      };
+
+      # Generate Home Manager specialisations for every non-base variant.
+      # Each is pre-built into the nix store during the single rebuild and
+      # activated userspace via `theme-switch` (no sudo, no OS rebuild).
+      specialisation = mapAttrs (name: variant: {
+        configuration = {
+          stylix = {
+            base16Scheme = mkForce variant.scheme;
+            polarity = mkForce variant.polarity;
+          };
+        };
+      }) specialisationVariants;
+    }
+  );
 }
diff --git a/hm-modules/theme/theme-switch.sh b/hm-modules/theme/theme-switch.sh
new file mode 100644
index 0000000..eb155a1
--- /dev/null
+++ b/hm-modules/theme/theme-switch.sh
@@ -0,0 +1,77 @@
+# shellcheck shell=bash
+# theme-switch — activate a pre-built Home Manager specialisation.
+#
+# Expects two variables to be injected by the Nix wrapper:
+#   baseVariant        the variant that is the generation itself (not a
+#                      specialisation), activated via `$gen/activate`.
+#   availableVariants  space-separated list of all variant names (help text).
+#
+# Standalone usage for testing:
+#   baseVariant=gruvbox-dark \
+#   availableVariants="gruvbox-dark gruvbox-light catppuccin-dark catppuccin-light" \
+#   bash theme-switch.sh <variant>
+
+: "${baseVariant:?theme-switch: baseVariant not set}"
+: "${availableVariants:?theme-switch: availableVariants not set}"
+set -euo pipefail
+
+variant="${1:-}"
+
+if [ -z "$variant" ]; then
+  echo "Usage: theme-switch <variant>"
+  echo "Available: ${availableVariants}"
+  exit 1
+fi
+
+# Resolve the Home Manager *base* generation — the one built by NixOS that
+# actually contains the `specialisation/` directory holding every variant's
+# activation script.
+#
+# IMPORTANT: do NOT use `current-home` / the HM profile as the primary
+# source. Activating a specialisation repoints those to the specialisation's
+# *leaf* generation, which has no `specialisation/` of its own — so after
+# switching once, every other variant (and the base) would become unfindable.
+# The NixOS-managed `home-manager-«user».service` unit references the base
+# generation and only changes on a rebuild.
+user="${USER:-$(id -un)}"
+gen=""
+if unit="$(systemctl cat "home-manager-${user}.service" 2>/dev/null)"; then
+  gen="$(printf '%s\n' "$unit" | grep -oE '/nix/store/[0-9a-z]+-home-manager-generation' | head -n1)"
+fi
+
+# Fallbacks for standalone Home Manager, where the profile symlink / gcroot
+# points at the base generation (not a specialisation leaf).
+for candidate in \
+  "${HOME}/.local/state/home-manager/gcroots/current-home" \
+  "/nix/var/nix/profiles/per-user/${user}/home-manager" \
+  "${HOME}/.local/state/home-manager/home-manager-generation"
+do
+  [ -n "$gen" ] && break
+  if [ -e "$candidate" ]; then
+    gen="$(readlink -e "$candidate")" || gen=""
+  fi
+done
+
+if [ -z "$gen" ]; then
+  echo "error: could not resolve Home Manager base generation" >&2
+  exit 1
+fi
+
+case "$variant" in
+  "${baseVariant}")
+    # Base variant is the generation itself, not a specialisation.
+    activate="$gen/activate"
+    ;;
+  *)
+    activate="$gen/specialisation/$variant/activate"
+    ;;
+esac
+
+if [ ! -x "$activate" ]; then
+  echo "error: variant '$variant' not found at $activate" >&2
+  echo "Available: ${availableVariants}"
+  exit 1
+fi
+
+echo "Switching theme to $variant..."
+exec "$activate"
diff --git a/machines/fujin/main/default.nix b/machines/fujin/main/default.nix
index 31f9a38..0b59dcf 100644
--- a/machines/fujin/main/default.nix
+++ b/machines/fujin/main/default.nix
@@ -121,8 +121,6 @@
     display-manager.ly.enable = true;
 
     gaming.enable = true;
-
-    dynamic-theme.enable = true;
   };
 
   ###
@@ -133,37 +131,14 @@
     useUserPackages = true;
     backupFileExtension = "backup";
     extraSpecialArgs = { inherit inputs username; };
+    # Stylix is handled entirely at the Home Manager level (see
+    # hm-modules/theme). Load the stylix HM module here so the `stylix`
+    # option exists for fujin's home configuration.
+    sharedModules = [ inputs.stylix.homeModules.stylix ];
 
     users."${username}" = { imports = [ ./home.nix ] ++ extraHomeModules; };
   };
 
-  stylix = {
-    enable = true;
-    # base16Scheme managed by dov.dynamic-theme module
-
-    fonts = {
-      serif = {
-        package = pkgs.dejavu_fonts;
-        name = "DejaVu Serif";
-      };
-
-      sansSerif = {
-        package = pkgs.dejavu_fonts;
-        name = "DejaVu Sans";
-      };
-
-      monospace = {
-        package = pkgs.dejavu_fonts;
-        name = "DejaVu Sans Mono";
-      };
-
-      emoji = {
-        package = pkgs.noto-fonts-color-emoji;
-        name = "Noto Color Emoji";
-      };
-    };
-  };
-
   fonts.packages = with pkgs;
     [
       noto-fonts
diff --git a/machines/fujin/main/home.nix b/machines/fujin/main/home.nix
index 6e25d2f..d40f9e3 100644
--- a/machines/fujin/main/home.nix
+++ b/machines/fujin/main/home.nix
@@ -163,12 +163,36 @@
     #mpc-cli
   ] ++ [ inputs.thefuck.packages.${pkgs.system}.default ];
 
+  # Stylix theming is driven by `dov.dynamic-theme` (hm-modules/theme),
+  # which sets `enable`, `base16Scheme` and `polarity` + specialisations.
+  # Here we only keep target overrides and the font set (moved from the
+  # old NixOS-level stylix config).
   stylix = {
-    enable = true;
-    autoEnable = true;
     targets = {
       kde.enable = false;
     };
+
+    fonts = {
+      serif = {
+        package = pkgs.dejavu_fonts;
+        name = "DejaVu Serif";
+      };
+
+      sansSerif = {
+        package = pkgs.dejavu_fonts;
+        name = "DejaVu Sans";
+      };
+
+      monospace = {
+        package = pkgs.dejavu_fonts;
+        name = "DejaVu Sans Mono";
+      };
+
+      emoji = {
+        package = pkgs.noto-fonts-color-emoji;
+        name = "Noto Color Emoji";
+      };
+    };
   };
 
   # blutooth applet
diff --git a/modules/default.nix b/modules/default.nix
index 7025821..39e19c4 100644
--- a/modules/default.nix
+++ b/modules/default.nix
@@ -15,6 +15,5 @@
     ./gitlab
     ./jenkins
     ./gaming
-    ./theme
   ];
 }
diff --git a/modules/theme/default.nix b/modules/theme/default.nix
deleted file mode 100644
index 481c934..0000000
--- a/modules/theme/default.nix
+++ /dev/null
@@ -1,65 +0,0 @@
-{ config, lib, pkgs, username, ... }:
-
-with lib;
-
-let
-  # Access HM theme config
-  hmCfg = config.home-manager.users.${username}.dov.dynamic-theme;
-  
-  allThemes = hmCfg.themes;
-
-  # Generate all theme-variant combinations
-  themeVariants = concatMapAttrs (name: theme: {
-    "${name}-dark" = { scheme = theme.dark; polarity = "dark"; };
-    "${name}-light" = { scheme = theme.light; polarity = "light"; };
-  }) allThemes;
-
-  # Base is gruvbox-dark, everything else is a specialisation
-  baseVariant = "gruvbox-dark";
-  specialisationVariants = filterAttrs (name: _: name != baseVariant) themeVariants;
-
-  availableVariants = concatStringsSep " " (attrNames themeVariants);
-
-  theme-switch = pkgs.writeShellScriptBin "theme-switch" ''
-    case "$1" in
-      ${baseVariant})
-        echo "Switching to ${baseVariant}..."
-        sudo nixos-rebuild switch --flake ~/nixos#${username}
-        ;;
-      ${concatStringsSep "\n      " (map (name: ''
-      ${name})
-        echo "Switching to ${name}..."
-        sudo nixos-rebuild switch --flake ~/nixos#${username} --specialisation ${name}
-        ;;'') (attrNames specialisationVariants))}
-      *)
-        echo "Usage: theme-switch <variant>"
-        echo "Available: ${availableVariants}"
-        exit 1
-        ;;
-    esac
-  '';
-
-in {
-  options.dov.dynamic-theme.enable = mkEnableOption "NixOS dynamic theme specialisations";
-
-  config = mkIf (config.dov.dynamic-theme.enable && hmCfg.enable) {
-    # Add theme-switch script system-wide
-    environment.systemPackages = [ theme-switch ];
-
-    # Base theme: gruvbox-dark
-    stylix = {
-      base16Scheme = mkDefault themeVariants.${baseVariant}.scheme;
-      polarity = mkDefault themeVariants.${baseVariant}.polarity;
-    };
-
-    # Generate NixOS specialisations for all other variants
-    specialisation = mapAttrs (name: variant: {
-      configuration = {
-        stylix = {
-          base16Scheme = mkForce variant.scheme;
-          polarity = mkForce variant.polarity;
-        };
-      };
-    }) specialisationVariants;
-  };
-}
diff --git a/modules/window-manager/hypr/default.nix b/modules/window-manager/hypr/default.nix
index dcf3ed3..95340dd 100644
--- a/modules/window-manager/hypr/default.nix
+++ b/modules/window-manager/hypr/default.nix
@@ -3,7 +3,6 @@
 with lib;
 
 let
-  colors = config.lib.stylix.colors;
   cfg = config.dov.window-manager.hypr;
   hm-cfg = config.home-manager.users.${username}.dov;
 in {
@@ -249,31 +248,6 @@ in {
         '';
       };
 
-      # Stylix base16 palette exported as hyprlang variables. No longer sourced
-      # from the main Lua config (Lua has no `source`); kept for reference and
-      # for any hyprlang consumer that wants to source it.
-      home.file.".config/hypr/colors".text = ''
-        $background = ${colors.base00}
-        $foreground = ${colors.base05}
-
-        $color0 = ${colors.base00}
-        $color1 = ${colors.base01}
-        $color2 = ${colors.base02}
-        $color3 = ${colors.base03}
-        $color4 = ${colors.base04}
-        $color5 = ${colors.base05}
-        $color6 = ${colors.base06}
-        $color7 = ${colors.base07}
-        $color8 = ${colors.base08}
-        $color9 = ${colors.base09}
-        $color10 = ${colors.base0A}
-        $color11 = ${colors.base0B}
-        $color12 = ${colors.base0C}
-        $color13 = ${colors.base0D}
-        $color14 = ${colors.base0E}
-        $color15 = ${colors.base0F}
-      '';
-
       xdg.configFile."hypr/hyprlock.conf".source = ./hyprlock.conf;
       xdg.configFile."hypr/hypridle.conf".source = ./hypridle.conf;