diff --git a/action.yml b/action.yml
index 646c3c6..457fc47 100644
--- a/action.yml
+++ b/action.yml
@@ -1,33 +1,48 @@
-name: 'Composite Action Template'
-description: 'Composite Action 範本'
+name: 'Codex CLI'
+description: 'Codex CLI 工具'
 author: 'Jeffery'
 inputs:
-  text:
-    description: '輸入的文字'
+  prompt:
+    description: '傳給 Codex CLI 的提示詞'
     required: false
-    default: 'Hello, World!'
+    default: "請自我介紹"
+  oauth:
+    description: 'base64 編碼的 Codex OAuth token 檔案內容'
+    required: true
 outputs:
   text:
     description: '輸出的文字'
-    value: ${{ steps.change.outputs.text }}
+    value: ${{ steps.codex.outputs.text }}
 runs:
   using: 'composite'
   steps:
-  - name: 交換
-    id: change
+  - name: 安裝工具
     env:
-      GITEA_SERVER_URL: ${{ gitea.server_url }}
-      GITEA_REPOSITORY: ${{ gitea.repository }}
-      GITEA_TOKEN: ${{ gitea.token }}
-      TEXT: ${{ inputs.text }}
+      OAUTH: ${{ inputs.oauth }}
     run: |
-      echo "Gitea Server Url: $GITEA_SERVER_URL"
+      npm install -g @openai/codex
 
-      echo "Gitea Repository: $GITEA_REPOSITORY"
+      oauth_file="$HOME/.codex/auth.json"
+      install -d -m 700 "$(dirname "$oauth_file")"
+      printf '%s' "$OAUTH" | base64 -d > "$oauth_file"
+      chmod 600 "$oauth_file"
+    shell: bash
+  - name: 執行工具
+    id: codex
+    env:
+      MODEL: ${{ vars.CODEX_MODEL }}
+      PROMPT: ${{ inputs.prompt }}
+    run: |
+      if [ -z "$MODEL" ]; then
+        echo 'CODEX_MODEL repository variable is required.' >&2
+        exit 1
+      fi
 
-      echo "Gitea Token: $GITEA_TOKEN"
-
-      echo "Text: $TEXT"
-
-      echo "text=$TEXT" >> "$GITHUB_OUTPUT"
-    shell: bash
\ No newline at end of file
+      text="$(codex exec --model "$MODEL" "$PROMPT")"
+      printf '%s\n' "$text"
+      {
+        echo 'text<<CODEX_OUTPUT'
+        printf '%s\n' "$text"
+        echo 'CODEX_OUTPUT'
+      } >> "$GITHUB_OUTPUT"
+    shell: bash