diff --git a/configuration.nix b/configuration.nix
index 4afe063..b42bb04 100644
--- a/configuration.nix
+++ b/configuration.nix
@@ -54,18 +54,18 @@
             esc = "capslock";
             leftalt = "leftcontrol";
             leftcontrol = "leftalt";
-            mute           = "mute";           # ← Key 1: mute
-            volumedown     = "playpause";      # ← Key 2: play/pause
-            volumeup       = "volumedown";     # ← Key 3: vol down
-            previoussong   = "volumeup";       # ← Key 4: vol up
-            playpause      = "command(touch /tmp/keyd-f5-test)"; # ← Key 5: lock screen (testing)
-            nextsong       = "noop";           # ← Key 6: disabled
-            brightnessdown = "noop";           # ← Key 7: disabled
-            brightnessup   = "noop";           # ← Key 8: disabled
+            mute = "mute"; # ← Key 1: mute
+            volumedown = "playpause"; # ← Key 2: play/pause
+            volumeup = "volumedown"; # ← Key 3: vol down
+            previoussong = "volumeup"; # ← Key 4: vol up
+            playpause = "command(touch /tmp/keyd-f5-test)"; # ← Key 5: lock screen (testing)
+            nextsong = "noop"; # ← Key 6: disabled
+            brightnessdown = "noop"; # ← Key 7: disabled
+            brightnessup = "noop"; # ← Key 8: disabled
             # Key 9: display toggle (leftmeta+p) - disabled below
-            rfkill         = "brightnessdown"; # ← Key 10: brightness down
-            sysrq          = "brightnessup";   # ← Key 11: brightness up
-            media          = "sysrq";          # ← Key 12: screenshot
+            rfkill = "brightnessdown"; # ← Key 10: brightness down
+            sysrq = "brightnessup"; # ← Key 11: brightness up
+            media = "sysrq"; # ← Key 12: screenshot
           };
         };
       };
@@ -73,8 +73,8 @@
         ids = [ "32ac:0006" ];
         settings = {
           main = {
-            brightnessdown = "noop";   # ← Key 7: disabled
-            brightnessup   = "noop";   # ← Key 8: disabled
+            brightnessdown = "noop"; # ← Key 7: disabled
+            brightnessup = "noop"; # ← Key 8: disabled
             rfkill = "brightnessdown"; # ← Key 10: brightness down
           };
         };
diff --git a/flake.lock b/flake.lock
index 2549491..643b686 100644
--- a/flake.lock
+++ b/flake.lock
@@ -20,6 +20,27 @@
         "type": "github"
       }
     },
+    "codex-cli-nix": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1773692150,
+        "narHash": "sha256-w95aHT9Q1Q3GfE4TR2El80g1Zn1wFOtMDhQhn5NQngo=",
+        "owner": "sadjow",
+        "repo": "codex-cli-nix",
+        "rev": "26a2d3fff58bd3d18e203f5e96f092c2f997883c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "sadjow",
+        "repo": "codex-cli-nix",
+        "type": "github"
+      }
+    },
     "flake-parts": {
       "inputs": {
         "nixpkgs-lib": [
@@ -41,6 +62,24 @@
         "type": "github"
       }
     },
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "home-manager": {
       "inputs": {
         "nixpkgs": [
@@ -157,6 +196,7 @@
     "root": {
       "inputs": {
         "claude-code-overlay": "claude-code-overlay",
+        "codex-cli-nix": "codex-cli-nix",
         "home-manager": "home-manager",
         "nix-index-database": "nix-index-database",
         "nixos-hardware": "nixos-hardware",
@@ -165,6 +205,21 @@
         "zen-browser": "zen-browser"
       }
     },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    },
     "zen-browser": {
       "inputs": {
         "home-manager": "home-manager_2",
diff --git a/flake.nix b/flake.nix
index 5faf8c9..901c9f6 100644
--- a/flake.nix
+++ b/flake.nix
@@ -22,6 +22,10 @@
       url = "github:ryoppippi/claude-code-overlay";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    codex-cli-nix = {
+      url = "github:sadjow/codex-cli-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs =
diff --git a/hardware-configuration.nix b/hardware-configuration.nix
index cf136b9..20e36c0 100644
--- a/hardware-configuration.nix
+++ b/hardware-configuration.nix
@@ -1,29 +1,44 @@
 # Do not modify this file!  It was generated by ‘nixos-generate-config’
 # and may be overwritten by future invocations.  Please make changes
 # to /etc/nixos/configuration.nix instead.
-{ config, lib, pkgs, modulesPath, ... }:
+{
+  config,
+  lib,
+  pkgs,
+  modulesPath,
+  ...
+}:
 
 {
-  imports =
-    [ (modulesPath + "/installer/scan/not-detected.nix")
-    ];
+  imports = [
+    (modulesPath + "/installer/scan/not-detected.nix")
+  ];
 
-  boot.initrd.availableKernelModules = [ "nvme" "xhci_pci" "thunderbolt" "usb_storage" "sd_mod" ];
+  boot.initrd.availableKernelModules = [
+    "nvme"
+    "xhci_pci"
+    "thunderbolt"
+    "usb_storage"
+    "sd_mod"
+  ];
   boot.initrd.kernelModules = [ ];
   boot.kernelModules = [ "kvm-amd" ];
   boot.extraModulePackages = [ ];
 
-  fileSystems."/" =
-    { device = "/dev/disk/by-uuid/687945b8-9e15-473d-b083-d3a3b12ac98f";
-      fsType = "ext4";
-      options = [ "noatime" ];
-    };
+  fileSystems."/" = {
+    device = "/dev/disk/by-uuid/687945b8-9e15-473d-b083-d3a3b12ac98f";
+    fsType = "ext4";
+    options = [ "noatime" ];
+  };
 
-  fileSystems."/boot" =
-    { device = "/dev/disk/by-uuid/407C-573B";
-      fsType = "vfat";
-      options = [ "fmask=0077" "dmask=0077" ];
-    };
+  fileSystems."/boot" = {
+    device = "/dev/disk/by-uuid/407C-573B";
+    fsType = "vfat";
+    options = [
+      "fmask=0077"
+      "dmask=0077"
+    ];
+  };
 
   swapDevices = [ ];
 
diff --git a/home.nix b/home.nix
index d74678f..ddf310f 100644
--- a/home.nix
+++ b/home.nix
@@ -85,6 +85,7 @@ in
     bat
     ffmpeg-full
     claude-code
+    inputs.codex-cli-nix.packages.${pkgs.stdenv.hostPlatform.system}.default
     fd
     btop
     fastfetch
@@ -234,10 +235,17 @@ in
   programs.bash = {
     enable = true;
     enableCompletion = true;
-    historyControl = [ "ignoredups" "erasedups" ];
+    historyControl = [
+      "ignoredups"
+      "erasedups"
+    ];
     historySize = 50000;
     historyFileSize = 100000;
-    shellOptions = [ "histappend" "checkwinsize" "globstar" ];
+    shellOptions = [
+      "histappend"
+      "checkwinsize"
+      "globstar"
+    ];
     shellAliases = {
       "dr" = "direnv reload";
       "da" = "direnv allow";
@@ -316,7 +324,12 @@ in
         editor = "hx";
         pager = "bat --style=plain";
       };
-      diff.tool = [ "difft" "--color=always" "$left" "$right" ];
+      diff.tool = [
+        "difft"
+        "--color=always"
+        "$left"
+        "$right"
+      ];
     };
   };