diff --git a/tests/modules/programs/codex/custom-instructions-prefer-xdg-directories.nix b/tests/modules/programs/codex/custom-instructions-prefer-xdg-directories.nix
deleted file mode 100644
index 81fa7df0..00000000
--- a/tests/modules/programs/codex/custom-instructions-prefer-xdg-directories.nix
+++ /dev/null
@@ -1,17 +0,0 @@
-{
-  home.preferXdgDirectories = true;
-  programs.codex = {
-    enable = true;
-    custom-instructions = ''
-      - Always respond with emojis
-      - Only use git commands when explicitly requested
-    '';
-  };
-  nmt.script = ''
-    assertFileContains home-path/etc/profile.d/hm-session-vars.sh \
-      'export CODEX_HOME="/home/hm-user/.config/codex"'
-    assertFileExists home-files/.config/codex/AGENTS.md
-    assertFileContent home-files/.config/codex/AGENTS.md \
-      ${./AGENTS.md}
-  '';
-}
diff --git a/tests/modules/programs/codex/custom-instructions.nix b/tests/modules/programs/codex/custom-instructions.nix
deleted file mode 100644
index 46b6a7e5..00000000
--- a/tests/modules/programs/codex/custom-instructions.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  programs.codex = {
-    enable = true;
-    custom-instructions = ''
-      - Always respond with emojis
-      - Only use git commands when explicitly requested
-    '';
-  };
-  nmt.script = ''
-    assertFileExists home-files/.codex/AGENTS.md
-    assertFileContent home-files/.codex/AGENTS.md \
-      ${./AGENTS.md}
-  '';
-}
diff --git a/tests/modules/programs/codex/default.nix b/tests/modules/programs/codex/default.nix
index d1cb7ddd..86e6e623 100644
--- a/tests/modules/programs/codex/default.nix
+++ b/tests/modules/programs/codex/default.nix
@@ -3,9 +3,6 @@
   codex-settings-toml-prefer-xdg-directories = ./settings-toml-prefer-xdg-directories.nix;
   codex-settings-yaml = ./settings-yaml.nix;
   codex-empty-settings = ./empty-settings.nix;
-  codex-custom-instructions = ./custom-instructions.nix;
-  codex-custom-instructions-prefer-xdg-directories = ./custom-instructions-prefer-xdg-directories.nix;
-  codex-empty-custom-instructions = ./empty-custom-instructions.nix;
   codex-mcp-integration = ./mcp-integration.nix;
   codex-mcp-integration-with-override = ./mcp-integration-with-override.nix;
   codex-skills-inline = ./skills-inline.nix;
diff --git a/tests/modules/programs/codex/empty-custom-instructions.nix b/tests/modules/programs/codex/empty-custom-instructions.nix
deleted file mode 100644
index 272ce1fb..00000000
--- a/tests/modules/programs/codex/empty-custom-instructions.nix
+++ /dev/null
@@ -1,9 +0,0 @@
-{
-  programs.codex = {
-    enable = true;
-    custom-instructions = "";
-  };
-  nmt.script = ''
-    assertPathNotExists home-files/.codex/AGENTS.md
-  '';
-}
diff --git a/tests/modules/programs/codex/empty-settings.nix b/tests/modules/programs/codex/empty-settings.nix
index c46da46b..2168834f 100644
--- a/tests/modules/programs/codex/empty-settings.nix
+++ b/tests/modules/programs/codex/empty-settings.nix
@@ -6,6 +6,7 @@
   nmt.script = ''
     assertPathNotExists home-files/.codex/config.toml
     assertPathNotExists home-files/.codex/config.yaml
+    assertPathNotExists home-files/.codex/AGENTS.md
     assertFileNotRegex home-path/etc/profile.d/hm-session-vars.sh 'CODEX_HOME'
   '';
 }
diff --git a/tests/modules/programs/codex/settings-toml-prefer-xdg-directories.nix b/tests/modules/programs/codex/settings-toml-prefer-xdg-directories.nix
index 191aed8d..e937296f 100644
--- a/tests/modules/programs/codex/settings-toml-prefer-xdg-directories.nix
+++ b/tests/modules/programs/codex/settings-toml-prefer-xdg-directories.nix
@@ -22,6 +22,10 @@ in
         };
       };
     };
+    custom-instructions = ''
+      - Always respond with emojis
+      - Only use git commands when explicitly requested
+    '';
   };
   nmt.script = ''
     assertFileContains home-path/etc/profile.d/hm-session-vars.sh \
@@ -29,5 +33,8 @@ in
     assertFileExists home-files/.config/codex/config.toml
     assertFileContent home-files/.config/codex/config.toml \
       ${./config.toml}
+    assertFileExists home-files/.config/codex/AGENTS.md
+    assertFileContent home-files/.config/codex/AGENTS.md \
+      ${./AGENTS.md}
   '';
 }
diff --git a/tests/modules/programs/codex/settings-toml.nix b/tests/modules/programs/codex/settings-toml.nix
index c3888587..68282b3a 100644
--- a/tests/modules/programs/codex/settings-toml.nix
+++ b/tests/modules/programs/codex/settings-toml.nix
@@ -21,11 +21,18 @@ in
         };
       };
     };
+    custom-instructions = ''
+      - Always respond with emojis
+      - Only use git commands when explicitly requested
+    '';
   };
   nmt.script = ''
     assertFileExists home-files/.codex/config.toml
     assertFileContent home-files/.codex/config.toml \
       ${./config.toml}
+    assertFileExists home-files/.codex/AGENTS.md
+    assertFileContent home-files/.codex/AGENTS.md \
+      ${./AGENTS.md}
     assertFileNotRegex home-path/etc/profile.d/hm-session-vars.sh 'CODEX_HOME'
   '';
 }