# Codex

> Orchestrates OpenAI Codex CLI from Claude Code via tmux. Use when delegating implementation tasks to Codex, running /codex with a prompt, or when parallel AI assistance in a separate pane is needed.

- Skill: `majiayu000/codex-7` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds add majiayu000/codex-7`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/codex-7/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/codex-7

---


# Codex Orchestration via tmux

Orchestrate OpenAI Codex CLI in a separate tmux pane for parallel AI-assisted development.

## Prerequisites

- Claude Code must be running inside a tmux session
- `codex` CLI must be available in PATH

## Workflow

### 1. Verify tmux Environment

Before proceeding, verify running inside tmux:

```bash
[ -n "$TMUX" ] && echo "Inside tmux" || echo "Not in tmux"
```

If not in tmux, inform the user and abort.

### 2. Prepare the Prompt

Construct a clear, self-contained prompt for Codex from `$ARGUMENTS`:

- **Plan references**: If user says "implement this plan", read the plan file and inline its contents
- **Context references**: If user references "the function above" or similar, resolve to actual code
- **File references**: If user mentions specific files, verify they exist

The final prompt must be fully self-contained -- Codex has no access to this conversation.

### 3. Manage the Codex Pane

Check for existing Codex pane or create one:

```bash
# List panes and check for one titled "codex"
CODEX_PANE=$(tmux list-panes -F '#{pane_id}:#{pane_title}' | grep ':codex$' | cut -d: -f1 | head -1)

if [ -z "$CODEX_PANE" ]; then
    # Create new pane (horizontal split, 50% height)
    CODEX_PANE=$(tmux split-window -v -P -F '#{pane_id}')
    # Set pane title
    tmux select-pane -t "$CODEX_PANE" -T "codex"
fi
```

### 4. Launch Codex

Send the Codex command to the pane. Required flags:

- `--sandbox danger-full-access` - Full filesystem access (REQUIRED)
- `-C <dir>` - Set working directory to current repo root
- `--full-auto` - Low-friction automatic execution (recommended for supervised use)

```bash
REPO_ROOT=$(git rev-parse --show-toplevel 2>/dev/null || pwd)
tmux send-keys -t "$CODEX_PANE" "codex --sandbox danger-full-access --full-auto -C '$REPO_ROOT' '$PROMPT'" Enter
```

For prompts with special characters, write to a temp file first:

```bash
PROMPT_FILE=$(mktemp)
cat > "$PROMPT_FILE" << 'EOF'
<your resolved prompt here>
EOF
tmux send-keys -t "$CODEX_PANE" "codex --sandbox danger-full-access --full-auto -C '$REPO_ROOT' < '$PROMPT_FILE'" Enter
```

### 5. Supervise Execution

Monitor Codex progress by periodically capturing pane output:

```bash
tmux capture-pane -t "$CODEX_PANE" -p -S -50
```

Supervision responsibilities:

- Watch for approval prompts that require user decision
- If Codex asks for approval on a reasonable action, send `y` + Enter
- If action seems destructive or off-track, send `n` + Enter and provide guidance
- If Codex gets stuck, send additional context or clarification

To send input to Codex pane:

```bash
tmux send-keys -t "$CODEX_PANE" "y" Enter
```

### 6. Detect Completion

Codex completion indicators:

- Pane shows shell prompt (Codex exited)
- Output contains "Task completed" or similar completion message
- No activity for extended period with shell prompt visible

To check if Codex is still running:

```bash
tmux list-panes -t "$CODEX_PANE" -F '#{pane_pid}' | xargs -I{} pgrep -P {} codex
```

### 7. Review Changes

After Codex completes, review all changes made:

```bash
git status
git diff
git ls-files --others --exclude-standard
```

Verification checklist:

- [ ] Changes align with original intent/plan
- [ ] No unintended modifications
- [ ] Code compiles/passes linting
- [ ] Tests pass (if applicable)
- [ ] No secrets or credentials committed

If changes are satisfactory, inform user. If issues found, either:

- Fix issues directly
- Instruct Codex to fix via the pane
- Report issues to user for decision

### 8. Cleanup (Optional)

To close the Codex pane when done:

```bash
tmux kill-pane -t "$CODEX_PANE"
```

## Example Usage

User: `/codex implement the authentication feature from our plan`

1. Read the plan file (e.g., `PLAN.md` or recent planning discussion)
2. Verify tmux environment
3. Create/reuse Codex pane
4. Launch: `codex --sandbox danger-full-access --full-auto -C /repo "Implement authentication feature: [extracted plan details]"`
5. Monitor progress, approve reasonable actions
6. On completion, run `git diff` and verify changes match plan
7. Report results to user

For CLI flag details, see [reference.md](reference.md).