Codex for Developers: Mastery — Automating Engineering with Codex

The expert level for engineers who set up Codex for a whole team. Learners standardise AGENTS.md across repositories, package team know-how as skills and plugins, connect tools through MCP, add hooks as guardrails, run Codex headless with codex exec and the official GitHub Action under least privilege, lock settings with organisation policy, defend against prompt injection, and measure cost and quality from real runs. They finish by automating one engineering workflow end to end.

What this course covers

The course runs across 11 topics, each one a short adaptive session rather than a recorded lecture. The tutor explains the idea, works an example, checks understanding, and adjusts the next step to the answer given.

Team conventions in AGENTS.md — Layer AGENTS.md across personal defaults, the repo root and subfolders, knowing the closest file wins. Keep each one short, point to task files such as code_review.md, and update it through a retrospective when Codex repeats a mistake.
Skills and plugins: packaging team know-how — Write focused SKILL.md skills with descriptions that trigger at the right time, keep team skills in .agents/skills, and share them more widely as plugins. Review what a plugin brings in, including any hooks, before you trust it.
MCP: connecting Codex to team tools and data — Add MCP servers in the app's settings or with codex mcp add, starting with one tool that removes a repeated manual step. Give each server the least access it needs and agree which servers the team allows.
Hooks as guardrails — Write a PreToolUse hook that blocks risky commands with a clear reason, trust and test it with /hooks, and know its limits: unsupported output lets the action continue, so back hooks with sandbox, approval and organisation settings.
Headless Codex with codex exec — Run Codex from scripts with codex exec, read its JSON event stream, constrain the final answer with an output schema, and keep the sandbox read-only unless the job must edit files. Use an API key from a secret store, never a personal sign-in.
Codex in GitHub Actions, safely — Use openai/codex-action@v1 with the right permission profile and safety strategy, read-only repository permissions in the Codex job, and a separate job that posts the result. Restrict who can trigger runs and treat pull requests from forks as untrusted.
Automated review at team scale — Turn on Codex review for pull requests, automatically or on @codex review, guided by the team's code_review.md. Decide which findings block a merge and keep a human as the owner of every merge.
Organisation policy and admin controls — Admins set limits users cannot override - allowed sandbox modes and approval policies, approved MCP servers and managed hooks - through the ChatGPT workspace's Codex policies or a system requirements file, and set sensible defaults separately. Codex Local and Codex Cloud access are controlled separately.
Security: prompt injection and secrets — Treat pull request text, issues, commit messages, web pages and tool output as untrusted instructions. Keep secrets away from agents, leave network access off unless a task needs it, and never let automation push to protected branches.
Measuring cost and quality from real runs — Pick reasoning effort per task, keep context lean and use subagents and worktrees for bounded parallel work. Measure tokens, run time, review time, acceptance rate and defects from real runs instead of guessing.
Capstone: automate one engineering workflow — Automate one real team workflow end to end: an AGENTS.md rule, a shared skill, a guardrail hook backed by policy, a least-privilege CI job, and a cost and quality note based on measured runs.

Skills you build

Results are measured against named skills in the OneRange taxonomy of more than 10,000 skills, so a manager sees proficiency per skill rather than a completion tick.

Who it is for

Senior developers, tech leads and platform teams who already use Codex daily (after Codex for Developers: Advanced or equivalent experience). The material is pitched at expert level, and takes roughly 180 minutes at a typical pace. Because every session adapts, someone who already knows a topic moves through it quickly instead of sitting through an explanation they do not need.

It sits in the Tool: Codex track of the Vero AI Catalog, and can be assigned to one person, a team, or the whole company.

How it is delivered and assessed

Delivery is conversational and interactive, including guided lab, code lab, branching scenario exercises. There is no video to sit through and no slide deck to click past.

Understanding is checked with a tool assessment of 5 items, with a pass mark of 70%.

Administrators can copy this course into their own library and adapt it — edit the outline, change the duration, swap the assessment format, or ground it in internal documentation so answers cite the company's own source material.

Also in this track

Codex for Everyone: Mastery — Owning Team Tools — The expert level for business builders whose Codex-built tools other people now depend on, built on the 4Ds of AI fluency: Delegation, Description, Discernment and Diligence. Learners decide what belongs in Codex, in ChatGPT Work, in Chat or with engineers, write specs an agent and an engineer can both follow, run a small portfolio of tools, review what agents produce, and work with IT on data, access and approved settings. They finish by measuring impact honestly and leading adoption on their team. No code.
Codex for Developers: Advanced — Automation & CI — An advanced course on running Codex as a serious engineering tool. Learners orchestrate parallel tasks, integrate with CI, manage large refactors safely, and set team guardrails for agentic development. They finish able to define how their team uses Codex at scale.
Codex for Everyone: Advanced — Multi-Step Tools & Agents — The advanced level for business builders whose Codex tools now have several steps or several users. Learners plan before building, split a bigger tool into steps they can each check, write rules in AGENTS.md that keep Codex consistent, save routines as skills, connect work apps carefully, hand work off to Codex in the cloud if their plan includes it, choose how much Codex may do without asking, and keep secrets and company data out. No code.
Codex for Developers: Core — A developer's working introduction to Codex, OpenAI's agentic coding tool. Learners delegate real tasks against a repository, manage context, review PR-style output, and keep human judgment in the loop. They finish using Codex daily with review discipline intact.
What's New in Codex — A short refresher on the latest Codex updates
Codex for Developers Pathway — Use Codex as a daily engineering tool, from your first week to automating engineering for a whole team. Also includes 4 optional playbooks to take any time after Essentials; they don't count toward the certificate.

Frequently asked questions

How long does this course take?

It runs roughly 180 minutes at a typical pace. Because every session adapts, someone who already knows a topic moves through it quickly instead of sitting through an explanation they do not need.

How is it assigned to a team?

An administrator assigns it from the Vero dashboard to one person, a team, a department or the whole company, and sees progress and results per person and per skill.

Can we customise it with our own documents and terminology?

Yes. Administrators can copy this course into their own library and adapt it — edit the outline, change the duration, swap the assessment format, or ground it in internal documentation so answers cite the company's own source material.

Course code TUL-CDX-DEV-301.