OpenAI Codex

#9Parallel Coding Agent & Independent Reviewer

How we work

1. What we use it for: We use OpenAI Codex (CLI and Desktop) as a second coding agent to run parallel feature branches, automated headless tasks, and independent code reviews against Claude Code’s output.

2. Client use case · A print and signage company and a members' dinner clubState: used

Problem

Having the same model write and review its own pull requests misses model-specific blind spots, and single-threaded sessions slow down multi-page website launches.

What the tool did

Shipped parallel `codex/*` branches (including merged PR #4 on a print and signage company’s site and PR #56 on a members’ dinner club’s site) and evaluated the temporary contact-form sender architecture during launch.

Result

Logged 3,254 indexed sessions across our stack since 2026-07-24: 1,302 automated `exec` runs, 660 subagent runs, 110 `guardian-review` runs, and 90 interactive sessions.

3. What it costs us or the client

$200/month on ChatGPT Pro (or $20/month Plus) plus metered OpenAI API usage for automated headless `codex exec` and review runs (as of 2026-10-22).

4. Setup notes (how it is wired in)

Configured via `~/.codex/config.toml` reading the same repository `AGENTS.md` instructions as Claude Code; runs either on isolated `codex/*` branches or as an automated `guardian-review` / `codex exec` worker checking diffs before merge.

5. What broke & how it was handled

Unbounded headless `exec` loops can burn through API rate limits if a test gate hangs, and on our own `moHelp` voice-and-camera repair guide we had to restrict live edits to Codex-only during quota windows—so every automated loop now runs with a lockfile, a pass cap, and a 429 cooldown.

6. What we compared it against & why we picked it

Compared against running a second Claude Code session as reviewer or delegating to Kimi, ZCode (GLM), or local Ollama (`qwen3.8:27b`). We picked OpenAI Codex as our primary second agent because cross-checking Anthropic code with an OpenAI reasoning model catches edge cases that same-model review misses.

7. Last reviewed: 2026-10-228. Video / tutorial: Episode 4 script package ready: "How We Run Claude Code + Codex + OpenBrain Across Client Builds"

All stack tools

Three separate steps. Stop after any of them.

Step 1 is a free 15-minute fit call. Step 2 is the AI Staff Assessment, $500, a written assessment you keep. Step 3 is your first hire at a published price, or you take the assessment and stop.

Step 1

Fit call

$0 · 15 min

tell me which job eats your week: the phone, the inbox, marketing or support
I tell you whether an AI hire fits, and whether I am the right person for it
you leave with the first hire I would start with
a slide deck

video call · same week

book it

Step 2

AI Staff Assessment

$500

a 60-minute video call about how your business runs
my written assessment the same day: whether an AI hire would pay for itself, the job I would hand off first, what to settle first, and the fixed price for that first hire
not taken off the build, and no separate quoting call: the assessment names the package at its published price
proposals written before anyone learned your business

paid when you book · not taken off the build

start here

Step 3

Your first hire

fixed price

Front Desk Hire or Brain + First Hire, at the published price
built in 2 to 6 weeks, then 30 days of tuning
or take the assessment and stop there
bench developers you never met

priced in the assessment

see the prices

Parallel Coding Agent & Independent ReviewerOpenAI Codex

OpenAI Codex

Three separate steps. Stop after any of them.

Fit call

AI Staff Assessment

Your first hire

Want OpenAI Codex wired into your business?