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Codex

**Tier:** Fully supported · **Repo:** a5c-ai/babysitter-codex · **Harness key:** codex

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In Plain English

**On Codex you get the full Babysitter experience through the $ mention picker: type $babysitter:call (and friends) to drive an orchestration run.**

Install the plugin once, and Babysitter surfaces as a set of skills you invoke from Codex's mention picker. The orchestration loop is driven by Codex's SessionStart + UserPromptSubmit + Stop hooks, auto-detected from the plugin's hooks.json.

**Estimated time to first run:** about 5 minutes. **End state:** you can mention $babysitter:call in Codex and watch a run iterate to a quality target.

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On this page

• Install
• Verify
• Command Surface
• Hook / Continuation Model
• First Run
• Related Documentation

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Install

# 1. Core CLI (host-side)
npm install -g @a5c-ai/babysitter

# 2a. Marketplace path (per-repo — the package repo ships its own
#     .agents/plugins/marketplace.json, so no --sparse needed)
codex plugin marketplace add a5c-ai/babysitter-codex
codex plugin list --marketplace babysitter
codex plugin add babysitter --marketplace babysitter

# 2a-alt. From the monorepo with a sparse checkout:
codex plugin marketplace add a5c-ai/babysitter --ref <released-tag> --sparse .agents/plugins

--marketplace babysitter is the marketplace **name** declared in the manifest, not the repo name.

For the monorepo form, use the released default branch / tag for --ref - **never** --ref staging. The Codex plugin publishes its own released tag; do not use a 6.0.x-staging.* build-metadata version.

**Alternative (npx installer):**

npx --yes @a5c-ai/babysitter-codex install --global
# or, scoped to a workspace:
npx --yes @a5c-ai/babysitter-codex install --workspace <path>

**Alternative (SDK helper):**

babysitter harness:install-plugin codex [--workspace <path>]

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Verify

After install, open Codex and bring up the mention picker ($). You should see the babysitter:* skills ($babysitter:babysit, $babysitter:call, ...). If they are missing, re-run codex plugin list --marketplace babysitter to confirm the plugin is registered.

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Command Surface

Codex surfaces Babysitter as skills through the $ **mention picker** (16 skills):

$babysitter:assimilate    $babysitter:babysit      $babysitter:call
$babysitter:doctor        $babysitter:forever      $babysitter:help
$babysitter:issue         $babysitter:model        $babysitter:observe
$babysitter:plan          $babysitter:project-install  $babysitter:resume
$babysitter:retrospect    $babysitter:team-install $babysitter:user-install
$babysitter:yolo

The core entry point is the babysit skill; $babysitter:call, $babysitter:plan, and $babysitter:resume are the wrappers you will use most. See Slash Commands and Modes.

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Hook / Continuation Model

**Model: SessionStart + UserPromptSubmit + Stop.**

• Plugin-level lifecycle hooks are auto-detected via ./hooks/hooks.json.
• The **proxied-stop** hook advances the orchestration loop after each turn.
• **UserPromptSubmit** participates in prompt handling.

This differs from Claude Code (which has no UserPromptSubmit in its loop) and from the non-Stop harnesses entirely. See Hooks for the full per-harness table.

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First Run

$babysitter:call build a calculator with add, subtract, multiply, divide using TDD

Babysitter creates a run and iterates toward your quality target, pausing for approval at breakpoints. Resume with $babysitter:resume.

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Related Documentation

• Installation · Quickstart
• Slash Commands and Modes
• Hooks · Adapters
• Install Matrix - all other supported harnesses
• Claude Code - the other fully-supported harness

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Next steps

• **Next:** Install Matrix
• **Related:** Claude Code, Slash Commands, Adapters