refactor(flake): Consolidate overlay configurations into shared functions

Extract duplicated overlay and home-manager configuration code into two
reusable factory functions:

- mkBaseOverlay: Creates the base overlay with unstable pkgs, custom
  packages, and bitwarden-desktop compatibility. Accepts optional
  unstableOverlays parameter for darwin-specific customizations.

- mkHomeManagerConfig: Creates home-manager configuration with shared
  settings (useGlobalPkgs, useUserPackages, doom-emacs module). Accepts
  sharedModules parameter for platform-specific modules like plasma-manager.

This reduces code duplication across nixosModules, nixosModulesUnstable,
and darwinModules, making the flake easier to maintain and extend.

Implements bead: nixos-configs-ek5

flake.nix

@@ -56,94 +56,75 @@
   };
 
   outputs = { self, nixpkgs, nixpkgs-unstable, nixos-wsl, ... } @ inputs: let
-    nixosModules = [
+    # Shared overlay function to reduce duplication across module sets
-      ./roles
+    # Parameters:
-    ] ++ [
+    #   unstableOverlays: Additional overlays to apply when importing nixpkgs-unstable
-      inputs.home-manager.nixosModules.home-manager
+    mkBaseOverlay = { unstableOverlays ? [] }: (final: prev: {
-      {
-        nixpkgs.overlays = [
-          (final: prev: {
       unstable = import nixpkgs-unstable {
         system = prev.stdenv.hostPlatform.system;
         config.allowUnfree = true;
+        overlays = unstableOverlays;
       };
       custom = prev.callPackage ./packages {};
       # Compatibility: bitwarden renamed to bitwarden-desktop in unstable
       bitwarden-desktop = prev.bitwarden-desktop or prev.bitwarden;
-          })
+    });
-        ];
+
+    # Shared home-manager configuration factory
+    # Parameters:
+    #   sharedModules: Additional modules to include in home-manager.sharedModules
+    mkHomeManagerConfig = { sharedModules ? [] }: {
       home-manager.useGlobalPkgs = true;
       home-manager.useUserPackages = true;
-        home-manager.sharedModules = [
+      home-manager.sharedModules = sharedModules ++ [
-          inputs.plasma-manager.homeModules.plasma-manager
         inputs.nix-doom-emacs-unstraightened.homeModule
       ];
       home-manager.extraSpecialArgs = {
         globalInputs = inputs;
       };
+    };
+
+    nixosModules = [
+      ./roles
+      inputs.home-manager.nixosModules.home-manager
+      {
+        nixpkgs.overlays = [ (mkBaseOverlay {}) ];
       }
+      (mkHomeManagerConfig {
+        sharedModules = [ inputs.plasma-manager.homeModules.plasma-manager ];
+      })
     ];
+
     # Modules for unstable-based systems (like nix-deck)
     nixosModulesUnstable = [
       ./roles
-    ] ++ [
       inputs.home-manager-unstable.nixosModules.home-manager
       inputs.jovian.nixosModules.jovian
       {
-        nixpkgs.overlays = [
+        nixpkgs.overlays = [ (mkBaseOverlay {}) ];
-          (final: prev: {
+      }
-            unstable = import nixpkgs-unstable {
+      (mkHomeManagerConfig {
-              system = prev.stdenv.hostPlatform.system;
+        sharedModules = [ inputs.plasma-manager-unstable.homeModules.plasma-manager ];
-              config.allowUnfree = true;
-            };
-            custom = prev.callPackage ./packages {};
-            # Compatibility: bitwarden renamed to bitwarden-desktop in unstable
-            bitwarden-desktop = prev.bitwarden-desktop or prev.bitwarden;
       })
     ];
-        home-manager.useGlobalPkgs = true;
+
-        home-manager.useUserPackages = true;
-        home-manager.sharedModules = [
-          inputs.plasma-manager-unstable.homeModules.plasma-manager
-          inputs.nix-doom-emacs-unstraightened.homeModule
-        ];
-        home-manager.extraSpecialArgs = {
-          globalInputs = inputs;
-        };
-      }
-    ];
     darwinModules = [
       ./roles/darwin.nix
-    ] ++ [
       inputs.home-manager.darwinModules.home-manager
       {
         nixpkgs.overlays = [
-          (final: prev: {
+          (mkBaseOverlay {
-            unstable = import nixpkgs-unstable {
-              system = prev.stdenv.hostPlatform.system;
-              config.allowUnfree = true;
-              overlays = [
             # Override claude-code in unstable to use our custom GCS-based build
             # (needed for corporate networks that block npm registry)
+            unstableOverlays = [
               (ufinal: uprev: {
-                  claude-code = prev.custom.claude-code or (prev.callPackage ./packages {}).claude-code;
+                claude-code = uprev.callPackage ./packages/claude-code {};
               })
             ];
-            };
-            custom = prev.callPackage ./packages {};
-            # Compatibility: bitwarden renamed to bitwarden-desktop in unstable
-            bitwarden-desktop = prev.bitwarden-desktop or prev.bitwarden;
           })
         ];
-        home-manager.useGlobalPkgs = true;
-        home-manager.useUserPackages = true;
-        home-manager.sharedModules = [
-          inputs.nix-doom-emacs-unstraightened.homeModule
-        ];
-        home-manager.extraSpecialArgs = {
-          globalInputs = inputs;
-        };
       }
+      (mkHomeManagerConfig { sharedModules = []; })
     ];
 
   in {

home/roles/communication/default.nix

@@ -4,7 +4,6 @@ with lib;
 
 let
   cfg = config.home.roles.communication;
-  isLinux = pkgs.stdenv.isLinux;
 in
 {
   options.home.roles.communication = {
@@ -13,14 +12,14 @@ in
 
   config = mkIf cfg.enable {
     home.packages = [
-      # For logging back into google chat (cross-platform)
+      # Communication apps
-      globalInputs.google-cookie-retrieval.packages.${system}.default
-    ] ++ optionals isLinux [
-      # Linux-only communication apps (Electron apps don't build on Darwin)
       pkgs.element-desktop
       # Re-enabled in 25.11 after security issues were resolved
       pkgs.fluffychat
       pkgs.nextcloud-talk-desktop
+      
+      # For logging back into google chat
+      globalInputs.google-cookie-retrieval.packages.${system}.default
     ];
   };
 }

home/roles/desktop/default.nix

@@ -4,7 +4,6 @@ with lib;
 
 let
   cfg = config.home.roles.desktop;
-  isLinux = pkgs.stdenv.isLinux;
 in
 {
   options.home.roles.desktop = {
@@ -13,29 +12,27 @@ in
 
   config = mkIf cfg.enable {
     home.packages = with pkgs; [
-      # Cross-platform desktop applications
+      # Desktop applications
       bitwarden-desktop
-      keepassxc
-      xdg-utils # XDG utilities for opening files/URLs with default applications
-    ] ++ optionals isLinux [
-      # Linux-only desktop applications
       dunst
+      keepassxc
       unstable.ghostty
       
-      # Linux-only desktop utilities
+      # Desktop utilities
       feh # Image viewer and wallpaper setter for X11
       rofi # Application launcher for X11
       solaar # Logitech management software
       waybar
       wofi # Application launcher for Wayland
+      xdg-utils # XDG utilities for opening files/URLs with default applications
       
-      # Linux-only system utilities with GUI components
+      # System utilities with GUI components
       (snapcast.override { pulseaudioSupport = true; })
       
-      # KDE tiling window management (Linux-only)
+      # KDE tiling window management
       kdePackages.krohnkite  # Dynamic tiling extension for KWin 6
       
-      # KDE PIM applications for email, calendar, and contacts (Linux-only)
+      # KDE PIM applications for email, calendar, and contacts
       kdePackages.kmail
       kdePackages.kmail-account-wizard
       kdePackages.kmailtransport
@@ -43,33 +40,33 @@ in
       kdePackages.kaddressbook
       kdePackages.kontact
       
-      # KDE System components needed for proper integration (Linux-only)
+      # KDE System components needed for proper integration
       kdePackages.kded
       kdePackages.systemsettings
       kdePackages.kmenuedit
       
-      # Desktop menu support (Linux-only)
+      # Desktop menu support
       kdePackages.plasma-desktop # Contains applications.menu
       
-      # KDE Online Accounts support (Linux-only)
+      # KDE Online Accounts support
       kdePackages.kaccounts-integration
       kdePackages.kaccounts-providers
       kdePackages.signond
       
-      # KDE Mapping (Linux-only)
+      # KDE Mapping
       kdePackages.marble  # Virtual globe and world atlas
       
-      # KDE Productivity (Linux-only)
+      # KDE Productivity
       kdePackages.kate        # Advanced text editor with syntax highlighting
       kdePackages.okular      # Universal document viewer (PDF, ePub, etc.)
       kdePackages.spectacle   # Screenshot capture utility
       kdePackages.filelight   # Visual disk usage analyzer
       
-      # KDE Multimedia (Linux-only)
+      # KDE Multimedia
       kdePackages.gwenview    # Image viewer and basic editor
       kdePackages.elisa       # Music player
       
-      # KDE System Utilities (Linux-only)
+      # KDE System Utilities  
       kdePackages.ark         # Archive manager (zip, tar, 7z, etc.)
       kdePackages.yakuake     # Drop-down terminal emulator
     ];
@@ -80,15 +77,12 @@ in
 
     programs.spotify-player.enable = true;
 
-    # Linux-only: GNOME keyring service
+    services.gnome-keyring = {
-    services.gnome-keyring = mkIf isLinux {
       enable = true;
     };
 
-    # Linux-only: systemd user services for rbw vault unlock
+    # rbw vault unlock on login and resume from suspend
-    systemd.user.services = mkIf isLinux {
+    systemd.user.services.rbw-unlock-on-login = {
-      # rbw vault unlock on login
-      rbw-unlock-on-login = {
       Unit = {
         Description = "Unlock rbw vault at login";
         After = [ "graphical-session.target" ];
@@ -107,8 +101,7 @@ in
       };
     };
 
-      # rbw vault unlock on resume from suspend
+    systemd.user.services.rbw-unlock-on-resume = {
-      rbw-unlock-on-resume = {
       Unit = {
         Description = "Unlock rbw vault after resume from suspend";
         After = [ "suspend.target" ];
@@ -126,10 +119,9 @@ in
         WantedBy = [ "suspend.target" ];
       };
     };
-    };
 
-    # Linux-only: KDE environment variables for proper integration
+    # KDE environment variables for proper integration
-    home.sessionVariables = mkIf isLinux {
+    home.sessionVariables = {
       QT_QPA_PLATFORMTHEME = "kde";
       KDE_SESSION_VERSION = "6";
     };
@@ -149,14 +141,13 @@ in
           "x-scheme-handler/https" = "firefox.desktop";
         };
         defaultApplications = {
-          # Web browsers (cross-platform)
+          # Web browsers
           "text/html" = "firefox.desktop";
           "x-scheme-handler/http" = "firefox.desktop";
           "x-scheme-handler/https" = "firefox.desktop";
           "x-scheme-handler/about" = "firefox.desktop";
           "x-scheme-handler/unknown" = "firefox.desktop";
-        } // optionalAttrs isLinux {
+          
-          # Linux-only: KDE application associations
           # Documents
           "application/pdf" = "okular.desktop";
           "text/plain" = "kate.desktop";
@@ -199,11 +190,9 @@ in
       };
     };
 
-    # Linux-only: Fix for KDE applications.menu file issue on Plasma 6
+    # Fix for KDE applications.menu file issue on Plasma 6
     # KDE still looks for applications.menu but Plasma 6 renamed it to plasma-applications.menu
-    xdg.configFile."menus/applications.menu" = mkIf isLinux {
+    xdg.configFile."menus/applications.menu".source = "${pkgs.kdePackages.plasma-workspace}/etc/xdg/menus/plasma-applications.menu";
-      source = "${pkgs.kdePackages.plasma-workspace}/etc/xdg/menus/plasma-applications.menu";
-    };
 
     # Note: modules must be imported at top-level home config
   };

home/roles/email/default.nix

@@ -4,7 +4,6 @@ with lib;
 
 let
   cfg = config.home.roles.email;
-  isLinux = pkgs.stdenv.isLinux;
 in
 {
   options.home.roles.email = {
@@ -90,9 +89,8 @@ in
       account default : proton
     '';
 
-    # Linux-only: Systemd service for mail sync (Darwin uses launchd instead)
+    # Systemd service for mail sync
-    systemd.user.services = mkIf isLinux {
+    systemd.user.services.mbsync = {
-      mbsync = {
       Unit = {
         Description = "Mailbox synchronization service";
         After = [ "network-online.target" ];
@@ -106,11 +104,9 @@ in
         StandardError = "journal";
       };
     };
-    };
 
-    # Linux-only: Systemd timer for automatic sync
+    # Systemd timer for automatic sync
-    systemd.user.timers = mkIf isLinux {
+    systemd.user.timers.mbsync = {
-      mbsync = {
       Unit = {
         Description = "Mailbox synchronization timer";
       };
@@ -124,5 +120,4 @@ in
       };
     };
   };
-  };
 }

home/roles/kdeconnect/default.nix

@@ -4,15 +4,13 @@ with lib;
 
 let
   cfg = config.home.roles.kdeconnect;
-  isLinux = pkgs.stdenv.isLinux;
 in
 {
   options.home.roles.kdeconnect = {
     enable = mkEnableOption "Enable KDE Connect for device integration";
   };
 
-  # KDE Connect services are Linux-only (requires D-Bus and systemd)
+  config = mkIf cfg.enable {
-  config = mkIf (cfg.enable && isLinux) {
     services.kdeconnect = {
       enable = true;
       indicator = true;

home/roles/sync/default.nix

@@ -4,7 +4,6 @@ with lib;
 
 let
   cfg = config.home.roles.sync;
-  isLinux = pkgs.stdenv.isLinux;
 in
 {
   options.home.roles.sync = {
@@ -12,10 +11,9 @@ in
   };
 
   config = mkIf cfg.enable {
-    # Linux-only: syncthingtray requires system tray support
+    home.packages = with pkgs; [
-    home.packages = optionals isLinux (with pkgs; [
       syncthingtray
-    ]);
+    ];
 
     services.syncthing = {
       enable = true;