codex skill

Codex CLI

Delegate coding tasks to Codex via the Hermes terminal. Codex is OpenAI's autonomous coding agent CLI.

When to use

• Building features
• Refactoring
• PR reviews
• Batch issue fixing

Requires the codex CLI and a git repository.

Prerequisites

from the Codex CLI login flow

• Codex installed: npm install -g @openai/codex
• OpenAI auth configured: either OPENAIAPIKEY or Codex OAuth credentials

• Must run inside a git repository — Codex refuses to run outside one
• Use pty=true in terminal calls — Codex is an interactive terminal app

For Hermes itself, model.provider: openai-codex uses Hermes-managed Codex OAuth from ~/.hermes/auth.json after hermes auth add openai-codex. For the standalone Codex CLI, a valid CLI OAuth session may live under ~/.codex/auth.json; do not treat a missing OPENAIAPIKEY alone as proof that Codex auth is missing.

One-Shot Tasks

terminal(command="codex exec 'Add dark mode toggle to settings'", workdir="~/project", pty=true)

For scratch work (Codex needs a git repo):

terminal(command="cd $(mktemp -d) && git init && codex exec 'Build a snake game in Python'", pty=true)

Background Mode (Long Tasks)

# Start in background with PTY
terminal(command="codex exec --sandbox workspace-write 'Refactor the auth module'", workdir="~/project", background=true, pty=true)
# Returns session_id

# Monitor progress
process(action="poll", session_id="<id>")
process(action="log", session_id="<id>")

# Send input if Codex asks a question
process(action="submit", session_id="<id>", data="yes")

# Kill if needed
process(action="kill", session_id="<id>")

Key Flags

Deprecated: --full-auto still works but the live CLI warns to use --sandbox workspace-write instead.

Hermes Gateway Caveat

When invoking the Codex CLI from a Hermes gateway/service context (for example, Telegram-driven agent sessions), Codex workspace-write sandboxing may fail even when the same command works in the user's interactive shell. A typical symptom is bubblewrap/user-namespace errors such as setting up uid map: Permission denied or loopback: Failed RTM_NEWADDR: Operation not permitted.

In that context, prefer:

codex exec --sandbox danger-full-access "<task>"

Use process boundaries as the safety layer instead: explicit workdir, clean git status before launch, narrow task prompts, git diff review, targeted tests, and human/agent confirmation before committing broad changes.

PR Reviews

Clone to a temp directory for safe review:

terminal(command="REVIEW=$(mktemp -d) && git clone https://github.com/user/repo.git $REVIEW && cd $REVIEW && gh pr checkout 42 && codex review --base origin/main", pty=true)

Parallel Issue Fixing with Worktrees

# Create worktrees
terminal(command="git worktree add -b fix/issue-78 ~/.hermes/cache/scratch/issue-78 main", workdir="~/project")
terminal(command="git worktree add -b fix/issue-99 ~/.hermes/cache/scratch/issue-99 main", workdir="~/project")

# Launch Codex in each
terminal(command="codex --sandbox workspace-write exec 'Fix issue #78: <description>. Commit when done.'", workdir="~/.hermes/cache/scratch/issue-78", background=true, pty=true)
terminal(command="codex --sandbox workspace-write exec 'Fix issue #99: <description>. Commit when done.'", workdir="~/.hermes/cache/scratch/issue-99", background=true, pty=true)

# Monitor
process(action="list")

# After completion, push and create PRs
terminal(command="cd ~/.hermes/cache/scratch/issue-78 && git push -u origin fix/issue-78")
terminal(command="gh pr create --repo user/repo --head fix/issue-78 --title 'fix: ...' --body '...'")

# Cleanup
terminal(command="git worktree remove ~/.hermes/cache/scratch/issue-78", workdir="~/project")

Batch PR Reviews

# Fetch all PR refs
terminal(command="git fetch origin '+refs/pull/*/head:refs/remotes/origin/pr/*'", workdir="~/project")

# Review multiple PRs in parallel
terminal(command="codex exec 'Review PR #86. git diff origin/main...origin/pr/86'", workdir="~/project", background=true, pty=true)
terminal(command="codex exec 'Review PR #87. git diff origin/main...origin/pr/87'", workdir="~/project", background=true, pty=true)

# Post results
terminal(command="gh pr comment 86 --body '<review>'", workdir="~/project")

Rules

1. Always use pty=true — Codex is an interactive terminal app and hangs without a PTY
2. Git repo required — Codex won't run outside a git directory. Use mktemp -d && git init for scratch
3. Use exec for one-shots — codex exec "prompt" runs and exits cleanly
4. --sandbox workspace-write for building — auto-approves changes within the sandbox (--full-auto is deprecated for this)
5. Background for long tasks — use background=true and monitor with process tool
6. Don't interfere — monitor with poll/log, be patient with long-running tasks
7. Parallel is fine — run multiple Codex processes at once for batch work