feat: add Codex integration support for agent installation

README.md

@@ -61,7 +61,7 @@ Stacks naturally form a tree structure—a single branch can have multiple child
 - 🔒 **Branch protection** — `lock` or `freeze` branches to prevent accidental modifications
 - 🔍 **Branch inspection** — Easily see parent/child relationships with `children` and `parent` commands
 - ⚙️ **Advanced configuration** — Customize branch naming patterns and submit behavior
-- 🤖 **AI assistant integration** — Generate integration files for Cursor and Claude Code
+- 🤖 **AI assistant integration** — Generate integration files for Cursor, Claude Code, and Codex
 - 🐙 **GitHub Integration** — Install CI checks to prevent merging locked PRs
 - ⚓ **Git Hooks** — Automatically validate branch state before committing with `precommit`
 - 📂 **Worktrees** — Work on multiple stacks in parallel with dedicated directories and post-creation hooks
@@ -189,13 +189,13 @@ Stackit includes specialized commands designed for Claude Code, providing intell
 | `stack-fix` | Diagnose and fix common stack issues | Resolving compilation errors or structural problems |
 | `stack-describe` | Generate or update stack description from changes | Documenting your stack for PRs |
 
-### Setting Up Claude Integration
+### Setting Up AI Agent Integration
 
 ```bash
 stackit agent install
 ```
 
-This creates the necessary integration files for Claude Code to use these specialized commands. The commands are designed to:
+This creates integration files for Claude Code, Codex, and Cursor. The Claude commands are designed to:
 
 - **Understand Context**: Each command analyzes your current stack state and git status
 - **Provide Validation**: Commands include quality checks and error handling
@@ -275,7 +275,7 @@ stack-submit --stack         # Creates/updates all PRs in the stack
 ### Integrations
 | Command | Description |
 |:---|:---|
-| `stackit agent install` | Setup integration files for Cursor and Claude Code |
+| `stackit agent install` | Setup integration files for Cursor, Claude Code, and Codex |
 | `stackit github install` | Install GitHub Action CI checks for branch locking |
 | `stackit precommit install` | Install git pre-commit hook for branch state validation |
 | `stackit precommit uninstall` | Remove the git pre-commit hook |

doc/src/integrations/claude.md

@@ -25,7 +25,7 @@ Install the Claude integration files:
 stackit agent install
 ```
 
-This creates the necessary integration files for Claude Code to use specialized stacking commands.
+This creates the necessary integration files for Claude Code, plus Codex/Cursor agent formats.
 
 ## Available commands
 

doc/src/integrations/index.md

@@ -12,13 +12,13 @@ Stackit integrates with your development tools to provide a seamless stacking wo
 
 <div class="grid cards" markdown>
 
--   :material-robot:{ .lg .middle } **Claude Code**
+-   :material-robot:{ .lg .middle } **AI Agents**
 
     ---
 
-    AI-assisted stacking with intelligent commands for creating, syncing, and managing stacks.
+    AI-assisted stacking with intelligent commands and skill files for Claude Code, Codex, and Cursor.
 
-    [Setup Claude →](claude.md)
+    [Setup agents →](claude.md)
 
 -   :material-github:{ .lg .middle } **GitHub**
 
@@ -51,7 +51,7 @@ Stackit integrates with your development tools to provide a seamless stacking wo
 Install all recommended integrations:
 
 ```bash
-# Claude Code integration
+# Agent integration (Claude Code + Codex + Cursor)
 stackit agent install
 
 # GitHub Actions
@@ -69,7 +69,7 @@ eval "$(stackit shell zsh)"  # or bash/fish
 
 | Integration | Purpose | Setup Command |
 |:------------|:--------|:--------------|
-| Claude Code | AI-assisted stacking commands | `stackit agent install` |
+| AI Agents (Claude/Codex/Cursor) | AI-assisted stacking commands | `stackit agent install` |
 | GitHub | CI checks for PRs | `stackit github install` |
 | Pre-commit hook | Block commits to locked branches | `stackit precommit install` |
 | Pre-push hook | Block pushes to locked branches | `stackit prepush install` |

internal/cli/init.go

@@ -139,7 +139,7 @@ func (h *cliInitHandler) offerIntegrations(splog output.Output) {
 	if agentsInstalled {
 		splog.Info("✓ AI agent files already installed")
 	} else {
-		installAgents, err := tui.PromptConfirm("Install AI agent files? (Claude Code / Cursor integration)", false)
+		installAgents, err := tui.PromptConfirm("Install AI agent files? (Claude Code / Codex integration)", false)
 		if err == nil && installAgents {
 			if err := integrations.InstallAgents(h.runner, false, false, h.version, h.writer); err != nil {
 				splog.Warn("Failed to install agent files: %v", err)