Add overlay for nixpkgs.

helpers.nix

@@ -11,31 +11,104 @@ with inputs.nixpkgs.lib; {
     user ? "fern",
     extraModules ? [],
   }: let
+    system = platform;
+    secrets = builtins.toString inputs.secrets;
+
+    pull-requests = {
+      fluffychat = import nixpkgs-pr-fluffychat {
+        inherit system;
+        overlays = [
+          (final: prev: {
+            fluffychat = prev.fluffychat.overrideAttrs (prevAttrs: rec {
+              desktopItems = [
+                ((builtins.elemAt prevAttrs.desktopItems 0).override {startupWMClass = "fluffychat";})
+              ];
+            });
+          })
+        ];
+      };
+
+      feishin = import nixpkgs-pr-feishin {
+        inherit system;
+        overlays = [
+          (final: prev: {
+            feishin = prev.feishin.overrideAttrs (prevAttrs: rec {
+              pname = "feishin";
+              version = "0.18.0";
+
+              src = prev.fetchFromGitHub {
+                owner = "jeffvli";
+                repo = "feishin";
+                rev = "v${version}";
+                hash = "sha256-4gcS7Vd7LSpEByO2Hlk6nb8V2adBPh5XwWGCu2lwOA4=";
+              };
+
+              pnpmDeps = prev.pnpm_10.fetchDeps {
+                inherit pname version src;
+                hash = "sha256-1MGxrUcfvazxAubaYAsQuulUKm05opWOIC7oaLzjr7o=";
+              };
+            });
+          })
+        ];
+      };
+    };
+
+    userPackages = final: prev: {
+      # WebOne HTTP proxy.
+      webone = prev.pkgs.callPackage ./packages/webone {};
+      # Yazi Gruvbox theme.
+      yazi-flavour-gruvbox-dark = prev.pkgs.callPackage ./packages/yazi-flavour-gruvbox {};
+      # Latest FluffyChat.
+      fluffychat = pull-requests.fluffychat.fluffychat;
+      # Latest Feishin.
+      feishin = pull-requests.feishin.feishin;
+      # PrismLauncher with Temurin JRE.
+      prismlauncher = prev.prismlauncher.override {
+        jdks = [
+          prev.pkgs.temurin-jre-bin
+        ];
+      };
+    };
+
+    pkgs = import nixpkgs {
+      inherit system;
+      config = {
+        allowUnfree = true;
+        permittedInsecurePackages = [
+          "dotnet-sdk-6.0.428"
+          "dotnet-runtime-6.0.36"
+        ];
+      };
+      overlays = [
+        userPackages
+      ];
+    };
+
+    deployPkgs = import nixpkgs {
+      inherit system;
+      overlays = [
+        deploy-rs.overlays.default
+        (self: super: {
+          deploy-rs = {
+            inherit (pkgs) deploy-rs;
+            lib = super.deploy-rs.lib;
+          };
+        })
+      ];
+    };
   in
     {
       nixosConfigurations.${hostname} = nixosSystem {
-        system = platform;
+        inherit system pkgs;
-        pkgs = import nixpkgs {
-          inherit system;
-          config = {
-            allowUnfree = true;
-            permittedInsecurePackages = [
-              "dotnet-sdk-6.0.428"
-              "dotnet-runtime-6.0.36"
-            ];
-          };
-          overlays = [(import ./overlay.nix inputs)];
-        };
 
         specialArgs = {
           inherit
-            nixpkgs
             hostname
             platform
             suite
             user
+            secrets
             ; # Inherit variables.
-          secrets = builtins.toString inputs.secrets;
         };
 
         modules =
@@ -49,13 +122,15 @@ with inputs.nixpkgs.lib; {
           ++ extraModules;
       };
     }
-    // optionalAttrs (suite != "desktop") {
+    // optionalAttrs ((suite == "server")
+      || (suite == "vm")
+      || (suite == "lxc")) {
       deploy.nodes.${hostname} = {
         hostname = "${hostname}.local";
         profiles.system = {
           user = "root";
           sshUser = user;
-          path = pkgs.deploy-rs.deploy-rs.lib.activate.nixos self.nixosConfigurations.${hostname};
+          path = deployPkgs.deploy-rs.lib.activate.nixos self.nixosConfigurations.${hostname};
         };
       };
     };

modules/webone.nix

@@ -1,7 +1,7 @@
 {
   config,
   lib,
-  userPackages,
+  pkgs,
   ...
 }:
 with lib; let
@@ -47,13 +47,13 @@ in {
       startLimitIntervalSec = 5;
       startLimitBurst = 3;
       environment = {
-        OPENSSL_CONF = "${userPackages.webone}/lib/webone/openssl_webone.cnf";
+        OPENSSL_CONF = "${pkgs.webone}/lib/webone/openssl_webone.cnf";
       };
       serviceConfig = {
         Type = "simple";
         User = "webone";
         Group = "webone";
-        ExecStart = "${userPackages.webone}/bin/webone";
+        ExecStart = "${pkgs.webone}/bin/webone";
         TimeoutStopSec = "10";
         Restart = "on-failure";
         RestartSec = "5";

suites/common.nix

@@ -1,6 +1,4 @@
 {
-  nixpkgs,
-  userPackages,
   pkgs,
   lib,
   hostname,
@@ -20,9 +18,6 @@ with lib; {
   # Add @wheel to trusted-users for remote deployments.
   nix.settings.trusted-users = ["root" "@wheel"];
 
-  # Set $NIX_PATH to flake input.
-  nix.nixPath = ["nixpkgs=${nixpkgs}"];
-
   # Enable redistributable firmware.
   hardware.enableRedistributableFirmware = true;
 
@@ -77,7 +72,7 @@ with lib; {
       # yazi cd on quit.
       function y
         set tmp (mktemp -t "yazi-cwd.XXXXXX")
-        ${pkgs.yazi}/bin/yazi $argv --cwd-file="$tmp"
+        yazi $argv --cwd-file="$tmp"
         if read -z cwd < "$tmp"; and [ -n "$cwd" ]; and [ "$cwd" != "$PWD" ]
           builtin cd -- "$cwd"
         end
@@ -89,10 +84,10 @@ with lib; {
   # https://nixos.wiki/wiki/Fish#Setting_fish_as_your_shell
   programs.bash = {
     interactiveShellInit = ''
-      if [[ $(${pkgs.procps}/bin/ps --no-header --pid=$PPID --format=comm) != "fish" && -z ''${BASH_EXECUTION_STRING} ]]
+      if [[ $(ps --no-header --pid=$PPID --format=comm) != "fish" && -z ''${BASH_EXECUTION_STRING} ]]
       then
         shopt -q login_shell && LOGIN_OPTION='--login' || LOGIN_OPTION=""
-        exec ${pkgs.fish}/bin/fish $LOGIN_OPTION
+        exec fish $LOGIN_OPTION
       fi
     '';
   };
@@ -107,9 +102,12 @@ with lib; {
 
     nixvim = {
       enable = true;
+      defaultEditor = true;
 
+      # For telescope.
       dependencies.ripgrep.enable = true;
 
+      # Space as leader.
       globals.mapleader = " ";
 
       keymaps = [
@@ -226,7 +224,7 @@ with lib; {
 
   programs.yazi = {
     enable = true;
-    flavors."gruvbox-dark.yazi" = userPackages.yazi-flavour-gruvbox-dark;
+    flavors."gruvbox-dark.yazi" = pkgs.yazi-flavour-gruvbox-dark;
     settings.theme = {
       flavor.dark = "gruvbox-dark";
     };

suites/desktop.nix

@@ -1,6 +1,5 @@
 {
   pkgs,
-  userPackages,
   lib,
   ...
 }:
@@ -48,8 +47,8 @@ with lib; {
   services.xserver = {
     enable = true;
 
-    excludePackages = with pkgs; [
+    excludePackages = [
-      xterm # Don't install xterm.
+      pkgs.xterm # Don't install xterm.
     ];
 
     displayManager.gdm.enable = true;
@@ -105,6 +104,8 @@ with lib; {
     celluloid
     deploy-rs
     discord
+    feishin
+    fluffychat
     ghostty
     gimp3
     glabels-qt
@@ -118,27 +119,12 @@ with lib; {
     merriweather-sans
     nerd-fonts.fira-code
     obsidian
+    prismlauncher
+    prismlauncher
     protonmail-desktop
     signal-desktop
     smile
-    userPackages.feishin
     yubioath-flutter
-
-    # PrismLauncher with temurin jre.
-    (prismlauncher.override {
-      jdks = [
-        temurin-jre-bin
-      ];
-    })
-
-    # FluffyChat 2.0.0 with fixed desktop item.
-    (userPackages.fluffychat.overrideAttrs (
-      finalAttrs: previousAttrs: {
-        desktopItems = [
-          ((builtins.elemAt previousAttrs.desktopItems 0).override {startupWMClass = "fluffychat";})
-        ];
-      }
-    ))
   ];
 
   # Allow opening terminal applications from gnome app launcher.