diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index ace1c5cc..6c09e253 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -34,6 +34,17 @@ jobs:
         with:
           persist-credentials: false
 
+      # TODO: Lock this Action to a release tag once commit [1] ("fix: relocate
+      # TMPDIR to /mnt to improve Nix installer compatibility") is part of a
+      # release, resolving [2] ("does not work with cachix install nix action").
+      #
+      # [1]: https://github.com/wimpysworld/nothing-but-nix/pull/25
+      # [2]: https://github.com/wimpysworld/nothing-but-nix/issues/24
+      - uses: wimpysworld/nothing-but-nix@10c936d9e46521bf923f75458e0cbd4fa309300d  # yamllint disable-line rule:line-length
+        if: runner.os == 'Linux'
+        with:
+          hatchet-protocol: holster
+
       - uses: cachix/install-nix-action@v31
 
       - uses: cachix/cachix-action@v16
diff --git a/modules/bat/testbeds/bat.nix b/modules/bat/testbeds/bat.nix
index 79f5446f..b7b0f17f 100644
--- a/modules/bat/testbeds/bat.nix
+++ b/modules/bat/testbeds/bat.nix
@@ -4,17 +4,7 @@ let
 in
 {
   environment = {
-    loginShellInit = "${lib.getExe package} example.md";
+    loginShellInit = "${lib.getExe package} flake-parts/flake.nix";
     systemPackages = [ package ];
   };
-  home-manager.sharedModules = [
-    {
-      home.file."example.md" = {
-        source = pkgs.fetchurl {
-          url = "https://raw.githubusercontent.com/sharkdp/bat/refs/heads/master/tests/syntax-tests/source/Markdown/example.md";
-          hash = "sha256-VYYwgRFY1c2DPY7yGM8oF3zG4rtEpBWyqfPwmGZIkcA=";
-        };
-      };
-    }
-  ];
 }
diff --git a/modules/emacs/testbeds/emacs.nix b/modules/emacs/testbeds/emacs.nix
index 22433683..6693970c 100644
--- a/modules/emacs/testbeds/emacs.nix
+++ b/modules/emacs/testbeds/emacs.nix
@@ -1,17 +1,11 @@
 { lib, pkgs, ... }:
-let
-  package = pkgs.emacs;
-in
 {
-  stylix.testbed.ui.application = {
-    name = "emacs";
-    inherit package;
-  };
+  stylix.testbed.ui.command.text = "emacs flake-parts/flake.nix";
 
   home-manager.sharedModules = lib.singleton {
     programs.emacs = {
       enable = true;
-      inherit package;
+      package = pkgs.emacs;
     };
   };
 }
diff --git a/modules/gedit/testbeds/gedit.nix b/modules/gedit/testbeds/gedit.nix
index 34979d48..3d988d60 100644
--- a/modules/gedit/testbeds/gedit.nix
+++ b/modules/gedit/testbeds/gedit.nix
@@ -1,12 +1,5 @@
 { pkgs, ... }:
-let
-  package = pkgs.gedit;
-in
 {
-  stylix.testbed.ui.application = {
-    name = "org.gnome.gedit";
-    inherit package;
-  };
-
-  environment.systemPackages = [ package ];
+  stylix.testbed.ui.command.text = "gedit flake-parts/flake.nix";
+  environment.systemPackages = [ pkgs.gedit ];
 }
diff --git a/modules/gnome-text-editor/testbeds/gnome-text-editor.nix b/modules/gnome-text-editor/testbeds/gnome-text-editor.nix
index 7950740e..2022e2b2 100644
--- a/modules/gnome-text-editor/testbeds/gnome-text-editor.nix
+++ b/modules/gnome-text-editor/testbeds/gnome-text-editor.nix
@@ -1,12 +1,5 @@
 { pkgs, ... }:
-let
-  package = pkgs.gnome-text-editor;
-in
 {
-  stylix.testbed.ui.application = {
-    name = "org.gnome.TextEditor";
-    inherit package;
-  };
-
-  environment.systemPackages = [ package ];
+  stylix.testbed.ui.command.text = "gnome-text-editor flake-parts/flake.nix";
+  environment.systemPackages = [ pkgs.gnome-text-editor ];
 }
diff --git a/modules/micro/testbeds/micro.nix b/modules/micro/testbeds/micro.nix
index 7f5ad445..5a722290 100644
--- a/modules/micro/testbeds/micro.nix
+++ b/modules/micro/testbeds/micro.nix
@@ -1,17 +1,11 @@
 { lib, pkgs, ... }:
 {
   stylix.testbed.ui.command = {
-    text = "${lib.getExe pkgs.micro} example.md";
+    text = "${lib.getExe pkgs.micro} flake-parts/flake.nix";
     useTerminal = true;
   };
 
   home-manager.sharedModules = lib.singleton {
     programs.micro.enable = true;
-    home.file."example.md" = {
-      source = pkgs.fetchurl {
-        url = "https://raw.githubusercontent.com/sharkdp/bat/e2aa4bc33cca785cab8bdadffc58a4a30b245854/tests/syntax-tests/source/Markdown/example.md";
-        hash = "sha256-VYYwgRFY1c2DPY7yGM8oF3zG4rtEpBWyqfPwmGZIkcA=";
-      };
-    };
   };
 }
diff --git a/modules/neovim/testbeds/neovide.nix b/modules/neovim/testbeds/neovide.nix
index aee8acfd..bbbabc6b 100644
--- a/modules/neovim/testbeds/neovide.nix
+++ b/modules/neovim/testbeds/neovide.nix
@@ -1,18 +1,12 @@
 { lib, pkgs, ... }:
-let
-  package = pkgs.neovide;
-in
 {
-  stylix.testbed.ui.application = {
-    name = "neovide";
-    inherit package;
-  };
+  stylix.testbed.ui.command.text = "neovide flake-parts/flake.nix";
 
   home-manager.sharedModules = lib.singleton {
     programs = {
       neovide = {
         enable = true;
-        inherit package;
+        package = pkgs.neovide;
       };
       neovim.enable = true;
     };
diff --git a/modules/neovim/testbeds/neovim.nix b/modules/neovim/testbeds/neovim.nix
index cd741d5f..823f1db7 100644
--- a/modules/neovim/testbeds/neovim.nix
+++ b/modules/neovim/testbeds/neovim.nix
@@ -1,17 +1,11 @@
-{ lib, pkgs, ... }:
+{ lib, ... }:
 {
   stylix.testbed.ui.command = {
-    text = "nvim example.md";
+    text = "nvim flake-parts/flake.nix";
     useTerminal = true;
   };
 
   home-manager.sharedModules = lib.singleton {
     programs.neovim.enable = true;
-    home.file."example.md" = {
-      source = pkgs.fetchurl {
-        url = "https://raw.githubusercontent.com/sharkdp/bat/e2aa4bc33cca785cab8bdadffc58a4a30b245854/tests/syntax-tests/source/Markdown/example.md";
-        hash = "sha256-VYYwgRFY1c2DPY7yGM8oF3zG4rtEpBWyqfPwmGZIkcA=";
-      };
-    };
   };
 }
diff --git a/modules/neovim/testbeds/nixvim.nix b/modules/neovim/testbeds/nixvim.nix
index 9294bb02..adc2364a 100644
--- a/modules/neovim/testbeds/nixvim.nix
+++ b/modules/neovim/testbeds/nixvim.nix
@@ -1,18 +1,8 @@
-{ lib, pkgs, ... }:
 {
   stylix.testbed.ui.command = {
-    text = "nvim example.md";
+    text = "nvim flake-parts/flake.nix";
     useTerminal = true;
   };
 
   programs.nixvim.enable = true;
-
-  home-manager.sharedModules = lib.singleton {
-    home.file."example.md" = {
-      source = pkgs.fetchurl {
-        url = "https://raw.githubusercontent.com/sharkdp/bat/refs/heads/master/tests/syntax-tests/source/Markdown/example.md";
-        hash = "sha256-VYYwgRFY1c2DPY7yGM8oF3zG4rtEpBWyqfPwmGZIkcA=";
-      };
-    };
-  };
 }
diff --git a/modules/neovim/testbeds/nvf.nix b/modules/neovim/testbeds/nvf.nix
index 5e6b6efc..9bfd5e74 100644
--- a/modules/neovim/testbeds/nvf.nix
+++ b/modules/neovim/testbeds/nvf.nix
@@ -1,18 +1,8 @@
-{ lib, pkgs, ... }:
 {
   stylix.testbed.ui.command = {
-    text = "nvim example.md";
+    text = "nvim flake-parts/flake.nix";
     useTerminal = true;
   };
 
   programs.nvf.enable = true;
-
-  home-manager.sharedModules = lib.singleton {
-    home.file."example.md" = {
-      source = pkgs.fetchurl {
-        url = "https://raw.githubusercontent.com/sharkdp/bat/refs/heads/master/tests/syntax-tests/source/Markdown/example.md";
-        hash = "sha256-VYYwgRFY1c2DPY7yGM8oF3zG4rtEpBWyqfPwmGZIkcA=";
-      };
-    };
-  };
 }
diff --git a/modules/neovim/testbeds/vim.nix b/modules/neovim/testbeds/vim.nix
index 745b218b..3bc44930 100644
--- a/modules/neovim/testbeds/vim.nix
+++ b/modules/neovim/testbeds/vim.nix
@@ -1,17 +1,11 @@
 { lib, pkgs, ... }:
 {
   stylix.testbed.ui.command = {
-    text = "${lib.getExe pkgs.vim} example.md";
+    text = "${lib.getExe pkgs.vim} flake-parts/flake.nix";
     useTerminal = true;
   };
 
   home-manager.sharedModules = lib.singleton {
     programs.vim.enable = true;
-    home.file."example.md" = {
-      source = pkgs.fetchurl {
-        url = "https://raw.githubusercontent.com/sharkdp/bat/e2aa4bc33cca785cab8bdadffc58a4a30b245854/tests/syntax-tests/source/Markdown/example.md";
-        hash = "sha256-VYYwgRFY1c2DPY7yGM8oF3zG4rtEpBWyqfPwmGZIkcA=";
-      };
-    };
   };
 }
diff --git a/modules/vscode/testbeds/vscode.nix b/modules/vscode/testbeds/vscode.nix
index 6ba6593e..06308854 100644
--- a/modules/vscode/testbeds/vscode.nix
+++ b/modules/vscode/testbeds/vscode.nix
@@ -1,18 +1,13 @@
 { lib, pkgs, ... }:
-# We are using VSCodium because VSCode is an unfree package
-let
-  package = pkgs.vscodium;
-in
 {
-  stylix.testbed.ui.application = {
-    name = "codium";
-    inherit package;
-  };
+  stylix.testbed.ui.command.text = "codium flake-parts/flake.nix";
 
   home-manager.sharedModules = lib.singleton {
     programs.vscode = {
       enable = true;
-      inherit package;
+
+      # We are using VSCodium because VSCode is an unfree package
+      package = pkgs.vscodium;
     };
   };
 }
diff --git a/modules/zed/testbeds/zed.nix b/modules/zed/testbeds/zed.nix
index 37ee282c..6a31fd14 100644
--- a/modules/zed/testbeds/zed.nix
+++ b/modules/zed/testbeds/zed.nix
@@ -1,16 +1,10 @@
 { lib, pkgs, ... }:
 {
   stylix.testbed.ui.command = {
-    text = "${lib.getExe pkgs.zed-editor} example.md";
+    text = "${lib.getExe pkgs.zed-editor} flake-parts/flake.nix";
   };
 
   home-manager.sharedModules = lib.singleton {
     programs.zed-editor.enable = true;
-    home.file."example.md" = {
-      source = pkgs.fetchurl {
-        url = "https://raw.githubusercontent.com/sharkdp/bat/e2aa4bc33cca785cab8bdadffc58a4a30b245854/tests/syntax-tests/source/Rust/output.rs";
-        hash = "sha256-vpUndD6H1oJfYVDai4LpVpsW6SSGbK466t3IKENZ1ow=";
-      };
-    };
   };
 }
diff --git a/stylix/testbed/default.nix b/stylix/testbed/default.nix
index da52f7b6..9053dde2 100644
--- a/stylix/testbed/default.nix
+++ b/stylix/testbed/default.nix
@@ -14,6 +14,7 @@ let
 
         modules =
           [
+            (lib.modules.importApply ./modules/flake-parts.nix inputs)
             ./modules/common.nix
             ./modules/enable.nix
             ./modules/application.nix
diff --git a/stylix/testbed/modules/flake-parts.nix b/stylix/testbed/modules/flake-parts.nix
new file mode 100644
index 00000000..b821eaca
--- /dev/null
+++ b/stylix/testbed/modules/flake-parts.nix
@@ -0,0 +1,7 @@
+inputs:
+{ lib, ... }:
+{
+  home-manager.sharedModules = lib.singleton {
+    home.file.flake-parts.source = inputs.flake-parts;
+  };
+}