Codex CLI 0.124.0: tighter rollback loops

Tighter review loops do not arrive in a changelog. They come from a rollback contract: a short repo note that tells a reviewer what to undo, and in what order, before the next agent run. We rehearsed this on Codex CLI 0.124.0, OpenAI's coding agent, and the version was never the bottleneck. The fix is not a longer prompt. It is a contract small enough that a tired reviewer reads it.

The test is one question. Why did the agent touch this file? If the only answer lives in a chat transcript, the loop is loose, no matter what the Codex CLI docs say.

Stop scrolling chat to learn what changed

During our rollback drills, review threads turned into archaeology. People scrolled chat history to reconstruct why the agent edited a file and which change came first. That is the symptom of a missing contract, not a missing feature.

Intent that lives in chat cannot be undone. A rollback needs a target state written down somewhere a reviewer can point at. So we moved the truth into AGENTS.md and stopped asking the version to do work that documentation should do.

The shape of the fix is four small notes, each aimed at one thing that breaks an undo plan.

Pin the model and roster your connectors

Four problems quietly make rollbacks harder. Here is each one and the short note that fixes it.

The model pin matters most during an upgrade week, because that is exactly when people swap models without thinking. The connector roster uses the MCP specification as shared language, so a security review starts grounded instead of guessing which server fired.

Put a verification snippet at the top of AGENTS.md

Keep the done checklist short. Ten lines or fewer, at the top of AGENTS.md, so Codex optimizes the right "done" and reviewers share one vocabulary. Here is a snippet you can paste today.

# AGENTS.md verification snippet

- Every Codex CLI run ends with the transcript snippet reviewers can replay.
- Pair browser evidence with the project's normal CLI checks before merge.
- If MCP servers are enabled, list allowed actions beside each connector name.

When a reviewer opens a PR, four gates answer the questions a rollback depends on.

The reviewer handoff comes down to four checks you can copy into a PR template.

• Scopes in the PR body match folders in the diff.
• Primary-doc links were smoke-checked after publishing edits.
• MCP connectors mentioned (if any) list owners.
• Verification command output is pasted or linked.

In our methodology, this is the Document step, and it has to happen before Review. The handoff should survive without the original operator in the room.

If your team is new to the tool, start from the quickstart, then watch the features page, the slash commands reference, and openai/skills for what each release adds. None of it replaces architecture judgement. Agents speed up execution, not ownership.

Common questions

• Does Codex CLI 0.124.0 tighten review loops on its own?

  No. Tighter loops come from the rollback contract, not the changelog. That means a short repo note saying what to undo and in what order, a pinned model, a connector roster, and a done checklist at the top of AGENTS.md. The version bump just sets the stage for the rehearsal.

• What belongs in a rollback contract for Codex runs?

  The shortest set a reviewer can act on: which scopes the run touched, the verification command output, which MCP connectors fired, and who approved sensitive paths. If a reviewer has to replay chat to answer any of those, the contract is not finished yet. Keep adding until none of them need the transcript.

• Why pin the model inside AGENTS.md during upgrades?

  Upgrade weeks invite casual model swaps, and casual swaps make review expectations wobble, because different models carry different risk appetite. The model pin note fixes the default and the escalation rule. Leads can then reason about blast radius while everything else around them is still changing.

• How do MCP connectors complicate a rollback?

  Each connector widens the blast radius an undo has to cover, and connectors tend to accumulate quietly until least-privilege has eroded. A Markdown roster checked into the repo root names every server and its owner. That is what lets the undo plan start from a grounded picture instead of a search.

• Where should I keep practicing this habit?

  Run it against real diffs, not toy examples. Read your most recent agent-assisted PR against the four gates and time how long the reviewer path question takes to answer. If it takes more than a minute, your contract is too long or in the wrong place.

Try it on your next rollback

If your review threads read like archaeology, run the four gates against your last agent-assisted PR and fix the slowest one. The drill repo for this habit is Codex CLI workflows.