# Codex Review

> Pre-PR code review on the current branch using the OpenAI Codex CLI, with an iterative fix loop.

- Skill: `ultimatile/codex-review` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ultimatile/codex-review`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ultimatile/codex-review/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: ultimatile (https://skillmd.com/u/ultimatile)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/ultimatile/codex-review

---


# Codex Review

Orchestrate `codex exec review` to review branch changes and iterate on fixes.

## The root

The caller supplies the **root** — the ref the change under review is measured from — on `diff-root`'s consumer contract. Apply that contract here, halt included. Every `--base` command below resolves the merge base in its own block, as that skill's per-command conversion requires.

## Core commands

### Review branch diff against base

```bash
mb=$(git merge-base <root-rev> HEAD)
test -n "$mb" || { echo "no merge base for <root>"; exit 1; }
codex exec review --base "$mb" -o <output-file> </dev/null
```

This runs `git diff <base-SHA>` internally and reviews the entire diff. The review covers all committed changes on the current branch relative to the base — both the original work and any subsequent fix commits.

### Other review modes

| Command | Scope |
| -- | -- |
| `codex exec review --uncommitted </dev/null` | Staged + unstaged + untracked changes |
| `codex exec review --commit <SHA> </dev/null` | A single commit's diff |
| `codex exec "<inline prompt>" </dev/null` | Free-form prompt with inline context (see "Switching to `exec` with inline context" below) |

### Output options

| Flag | Effect |
| -- | -- |
| `-o <file>` | Write final review message to file |
| `--json` | Emit JSONL event stream to stdout |
| `"custom prompt"` | Positional arg — additional review instructions |

## Switching to `exec` with inline context

`codex exec review --base ...` operates on `git diff` alone — it cannot read GitHub Issues, ADRs, or any design intent encoded outside the diff. For self-contained changes this is fine; for **phased rollouts** where the judgement criteria live outside the diff, `review` mode systematically misjudges intentional design decisions as regressions. Switch to free-form `codex exec "<inline prompt>"` to attach the context.

**Trigger — before every codex review, check:**

- Is this commit part of a numbered phase in a tracked Issue?
- Does the relevant ADR contain phrases like "unmeasured → sentinel X", "tracked separately in a follow-up", "intentional default until <later phase>", "out of this phase's scope"?
- Are there thresholds, defaults, or scoped-off paths that look like bugs from the diff but are ADR / Issue-intentional?

If any of the above is yes, skip `codex exec review` and use `codex exec "<inline prompt>"` instead.

**Why the workaround is needed:** `--base` and the positional `[PROMPT]` are mutually exclusive on `codex exec review`, so phase context cannot be attached to a `review` invocation. The free-form `codex exec "..."` accepts an arbitrary prompt that can direct codex to read the surrounding context first.

**Inline prompt template** — the prompt should tell codex to:

1. Run `git log <root-rev>..HEAD --oneline` and `git show <sha>` to read the commits.
2. Read the tracking Issue (`gh issue view <n>`) and the relevant ADRs (pass absolute paths so codex doesn't have to search).
3. Enumerate explicitly which states are intentional (sentinel values, scoped-off paths, deferred behaviors) and must NOT be flagged as regressions.
4. List what the review should focus on (forwarding correctness, default / expert contract consistency, docstring drift, missed call sites, etc. — project-specific).
5. List what to ignore — the enumerated intentional states from step 3.

**For non-phased self-contained changes**, keep using vanilla `codex exec review --base ...` in the form Core commands gives. The inline-context workaround is only needed when judgement criteria live outside the diff.

## Triaging review output

codex review operates on `git diff` output alone — it has no access to the broader project context, test results, runtime behavior, or design rationale. This means a significant fraction of its findings will be false positives: technically plausible concerns that don't apply given information the reviewer can't see.

Typical false positive patterns:

- **Assumed standard behavior**: "this regex won't match standard X format" when the actual data uses a project-specific format (verified by tests)
- **Missing context on intentional decisions**: flagging a design choice as a bug when it was deliberate and tested
- **Hypothetical edge cases**: warning about inputs that can't occur given the system's constraints

When presenting review output, triage each finding:

1. **Read the review output** and identify each distinct finding (usually formatted as `[P1/P2] summary — file:line`)
2. **Cross-check against project context** you already have — test results, prior conversation, code you've read. You have far more context than the reviewer did.
3. **Classify each finding** under the `finding-triage` SSOT dispositions, applying each per its definition there. The common codex-review cases are `actionable`, `false-positive`, and `uncertain-validity`.
4. **Present the triage** to the user, not the raw output. Lead with actionable items, note dismissed items with reasoning.

## Review-fix loop

Each iteration runs a full, unbiased review of the entire diff against base. Do NOT inject previous review comments into the prompt — this narrows the reviewer's focus and risks missing new regressions introduced by the fix. The reviewer should always see the code with fresh eyes.

### Procedure

1. **Run review**

   ```bash
   mb=$(git merge-base <root-rev> HEAD)
   test -n "$mb" || { echo "no merge base for <root>"; exit 1; }
   codex exec review --base "$mb" -o /tmp/codex-review.md </dev/null
   ```

2. **Triage the output** using the process above. Present classified findings to the user.

3. **If actionable issues are found**, the user (or Claude) fixes them and commits.

4. **Re-run the review** — same command, same flags. The new diff includes the fix commits, so the reviewer sees the full picture: original changes plus fixes.

5. **Re-triage** — a finding dismissed as false positive in iteration N may become relevant in iteration N+1 if the fix changed the surrounding code. Don't carry over dismissals blindly.

6. **Repeat** until no actionable findings remain, or the user explicitly waives the remainder with reasoning — a waived finding no longer stands as an open actionable finding, in this loop and in any loop wrapping it.

### What "clean" means

No open actionable findings after triage. A review with only false positives counts as clean; a valid but minor finding keeps whichever SSOT disposition it earns — minor-ness alone never makes it clean.

## Important constraints

- **Stdin redirect**: every `codex exec` invocation needs `</dev/null`; hang signal is absence of the `OpenAI Codex v...` banner after `Reading additional input from stdin...`.
- **Run fresh**: run each review with fresh context — fresh reviews are the correct approach for iteration.
- **Non-interactive only**: Always use `codex exec review`, not `codex review`, when running from scripts or automation. The `exec` variant runs non-interactively and exits when done.
- **Timeout**: Set timeout to 600000ms (10 minutes) when calling from Bash. Reviews of large diffs can take several minutes.