feat(codex): add support for codex openai

README.md

@@ -44,6 +44,7 @@
 - [Cline](#cline)
 - [Claude Code](#claude-code)
 - [GitHub Copilot](#github-copilot)
+- [OpenAI Codex](#openai-codex)
 - [Other Agents](#other-agents)
 
 ---
@@ -95,7 +96,7 @@
 Open the steering files panel and confirm you see an entry for `core-workflow` under `Workspace` as shown in the screenshot below.
 
 <img src="./assets/images/kiro-ide-aidlc-rules-loaded.png?raw=true" alt="AI-DLC Rules in Kiro IDE" width="700" height="450">
 
 We use Kiro IDE in Vibe mode to run the AI-DLC workflow. This ensures that AI-DLC workflow guides the development workflow in Kiro. At times, Kiro may nudge you to switch to spec mode. Select `No` to such prompts to stay in Vibe mode.
 
 <img src="./assets/images/kiro-sdd-nudge.png?raw=true" alt="Staying in Kiro Vibe mode" width="500" height="175">
@@ -496,6 +497,64 @@
 
 ---
 
+### OpenAI Codex
+
+AI-DLC supports OpenAI Codex as one of its compatible IDEs, using the [Codex AGENTS.md](https://developers.openai.com/codex/guides/agents-md) convention to deliver its intelligent workflow. Codex automatically discovers and loads `AGENTS.md` from your project root when you start a session.
+
+The commands below assume you extracted the zip to your `Downloads` folder. If you used a different location, replace `Downloads` with your actual folder path.
+
+**Unix/Linux/macOS:**
+
+```bash
+cp ~/Downloads/aidlc-rules/aws-aidlc-rules/core-workflow.md ./AGENTS.md
+mkdir -p .aidlc-rule-details
+cp -R ~/Downloads/aidlc-rules/aws-aidlc-rule-details/* .aidlc-rule-details/
+```
+
+**Windows PowerShell:**
+
+```powershell
+Copy-Item "$env:USERPROFILE\Downloads\aidlc-rules\aws-aidlc-rules\core-workflow.md" ".\AGENTS.md"
+New-Item -ItemType Directory -Force -Path ".aidlc-rule-details"
+Copy-Item "$env:USERPROFILE\Downloads\aidlc-rules\aws-aidlc-rule-details\*" ".aidlc-rule-details\" -Recurse
+```
+
+**Windows CMD:**
+
+```cmd
+copy "%USERPROFILE%\Downloads\aidlc-rules\aws-aidlc-rules\core-workflow.md" ".\AGENTS.md"
+mkdir .aidlc-rule-details
+xcopy "%USERPROFILE%\Downloads\aidlc-rules\aws-aidlc-rule-details" ".aidlc-rule-details\" /E /I
+```
+
+**Verify Setup:**
+
+1. Start a Codex session in your project directory
+2. Ask Codex: For existing project - "Using AIDLC analyse the project?" or For new project "Using Aidlc what workflow do you see" .
+3. Codex should describe the AI-DLC three-phase workflow (Inception → Construction → Operations)
+
+> [!NOTE]
+> The `AGENTS.md` file is designed to fit within Codex's instruction budget under default settings. If you add substantial project-specific content and Codex reports that the project documentation exceeds its instruction limit, you can increase the limit in your Codex configuration (for example, by adjusting `project_doc_max_bytes` in your `config.toml` file):
+>
+> ```toml
+> project_doc_max_bytes = 65536  # Example value; choose a limit appropriate for your project
+> ```
+
+**Directory Structure:**
+
+```text
+<my-project>/
+├── AGENTS.md
+└── .aidlc-rule-details/
+    ├── common/
+    ├── inception/
+    ├── construction/
+    ├── extensions/
+    └── operations/
+```
+
+---
+
 ### Other Agents
 
 AI-DLC works with any coding agent that supports project-level rules or steering files. The general approach:

aidlc-rules/aws-aidlc-rules/core-workflow.md

@@ -13,7 +13,7 @@
 ## MANDATORY: Rule Details Loading
 **CRITICAL**: When performing any phase, you MUST read and use relevant content from rule detail files. Check these paths in order and use the first one that exists, regardless of which IDE or setup method was used:
 - `.aidlc/aidlc-rules/aws-aidlc-rule-details/` (typical with AI-assisted setup)
-- `.aidlc-rule-details/` (typical with Cursor, Cline, Claude Code, GitHub Copilot)
+- `.aidlc-rule-details/` (typical with Cursor, Cline, Claude Code, GitHub Copilot, OpenAI Codex)
 - `.kiro/aws-aidlc-rule-details/` (typical with Kiro IDE and CLI)
 - `.amazonq/aws-aidlc-rule-details/` (typical with Amazon Q Developer)