diff --git a/tests/modules/programs/codex/default.nix b/tests/modules/programs/codex/default.nix
index 6341172a..d1cb7ddd 100644
--- a/tests/modules/programs/codex/default.nix
+++ b/tests/modules/programs/codex/default.nix
@@ -9,6 +9,8 @@
   codex-mcp-integration = ./mcp-integration.nix;
   codex-mcp-integration-with-override = ./mcp-integration-with-override.nix;
   codex-skills-inline = ./skills-inline.nix;
+  codex-skills-inline-null-package = ./skills-inline-null-package.nix;
+  codex-skills-inline-legacy-path = ./skills-inline-legacy-path.nix;
   codex-skills-dir = ./skills-dir.nix;
   codex-skills-path-not-directory = ./skills-path-not-directory.nix;
 }
diff --git a/tests/modules/programs/codex/skills-dir.nix b/tests/modules/programs/codex/skills-dir.nix
index f3fbd20b..eaa48d53 100644
--- a/tests/modules/programs/codex/skills-dir.nix
+++ b/tests/modules/programs/codex/skills-dir.nix
@@ -1,12 +1,20 @@
+{ config, ... }:
+let
+  codexPackage = config.lib.test.mkStubPackage {
+    name = "codex";
+    version = "0.94.0";
+  };
+in
 {
   programs.codex = {
     enable = true;
+    package = codexPackage;
     skills = ./skills-dir;
   };
 
   nmt.script = ''
-    assertFileExists home-files/.codex/skills/skill-one/SKILL.md
-    assertFileContent home-files/.codex/skills/skill-one/SKILL.md \
+    assertFileExists home-files/.agents/skills/skill-one/SKILL.md
+    assertFileContent home-files/.agents/skills/skill-one/SKILL.md \
       ${./skills-dir/skill-one/SKILL.md}
   '';
 }
diff --git a/tests/modules/programs/codex/skills-inline-legacy-path.nix b/tests/modules/programs/codex/skills-inline-legacy-path.nix
new file mode 100644
index 00000000..5030a40f
--- /dev/null
+++ b/tests/modules/programs/codex/skills-inline-legacy-path.nix
@@ -0,0 +1,26 @@
+{ config, ... }:
+let
+  codexPackage = config.lib.test.mkStubPackage {
+    name = "codex";
+    version = "0.93.0";
+  };
+in
+{
+  programs.codex = {
+    enable = true;
+    package = codexPackage;
+    skills = {
+      inline-skill = ''
+        # Inline Skill
+      '';
+    };
+  };
+
+  nmt.script = ''
+    assertFileExists home-files/.codex/skills/inline-skill/SKILL.md
+    assertFileContent home-files/.codex/skills/inline-skill/SKILL.md \
+      ${builtins.toFile "expected-inline-skill.md" ''
+        # Inline Skill
+      ''}
+  '';
+}
diff --git a/tests/modules/programs/codex/skills-inline-null-package.nix b/tests/modules/programs/codex/skills-inline-null-package.nix
new file mode 100644
index 00000000..c3bc019f
--- /dev/null
+++ b/tests/modules/programs/codex/skills-inline-null-package.nix
@@ -0,0 +1,19 @@
+{
+  programs.codex = {
+    enable = true;
+    package = null;
+    skills = {
+      inline-skill = ''
+        # Inline Skill
+      '';
+    };
+  };
+
+  nmt.script = ''
+    assertFileExists home-files/.agents/skills/inline-skill/SKILL.md
+    assertFileContent home-files/.agents/skills/inline-skill/SKILL.md \
+      ${builtins.toFile "expected-inline-skill.md" ''
+        # Inline Skill
+      ''}
+  '';
+}
diff --git a/tests/modules/programs/codex/skills-inline.nix b/tests/modules/programs/codex/skills-inline.nix
index e10c4b60..80ad05de 100644
--- a/tests/modules/programs/codex/skills-inline.nix
+++ b/tests/modules/programs/codex/skills-inline.nix
@@ -1,4 +1,9 @@
+{ config, ... }:
 let
+  codexPackage = config.lib.test.mkStubPackage {
+    name = "codex";
+    version = "0.94.0";
+  };
   inlineSkill = ''
     ---
     name: inline-skill
@@ -13,6 +18,7 @@ in
 {
   programs.codex = {
     enable = true;
+    package = codexPackage;
     skills = {
       inline-skill = inlineSkill;
       file-skill = ./skill-file.md;
@@ -20,11 +26,11 @@ in
   };
 
   nmt.script = ''
-    assertFileExists home-files/.codex/skills/inline-skill/SKILL.md
-    assertFileContent home-files/.codex/skills/inline-skill/SKILL.md \
+    assertFileExists home-files/.agents/skills/inline-skill/SKILL.md
+    assertFileContent home-files/.agents/skills/inline-skill/SKILL.md \
       ${builtins.toFile "expected-inline-skill.md" inlineSkill}
-    assertFileExists home-files/.codex/skills/file-skill/SKILL.md
-    assertFileContent home-files/.codex/skills/file-skill/SKILL.md \
+    assertFileExists home-files/.agents/skills/file-skill/SKILL.md
+    assertFileContent home-files/.agents/skills/file-skill/SKILL.md \
       ${./skill-file.md}
   '';
 }