Codex Review Unstaged

Use codex exec as an independent reviewer on the working-tree changes Claude just made. Codex sees only the summary + diff (no conversation history), so its critique catches things Claude rationalized into "good enough" during implementation. The output is a prioritized iteration plan — what to fix now, what to defer, what to reject.

• When to use
• Instructions
• Codex prompt
• Output format
• Notes

When to use

• After Claude finishes a non-trivial implementation pass and before commit
• When the user says "review my changes with codex", "have codex check what I just did", or /cmd-codex-review-unstaged
• As an outside cross-check before opening a PR — complements cmd-follow-up (Claude self-review) and cmd-pr-edgecase (edge-case sweep) by adding a fresh pair of eyes that didn't write the code

Instructions

1. Build Claude's implementation summary

Write a short summary of what was just implemented. Keep it factual, not promotional:

• What was the goal?
• What files changed and why?
• What design decisions were made (and what was rejected)?
• What was deliberately deferred (TODOs, follow-ups, scope cuts)?
• What was tested manually vs. covered by automated tests?

This summary anchors codex's review — without it, codex will judge the diff against a generic standard instead of the actual intent.

2. Capture the diff

Default scope: git diff HEAD — captures both staged and unstaged working-tree changes since the last commit.

DIFF_FILE=$(mktemp -t codex-diff.XXXXXX.patch)
SUMMARY_FILE=$(mktemp -t codex-summary.XXXXXX.md)
OUT_FILE=$(mktemp -t codex-review.XXXXXX.md)

git diff HEAD > "$DIFF_FILE"
git status --short >> "$DIFF_FILE"

If the user explicitly asks for unstaged-only or branch diff, swap in:

• Unstaged only: git diff
• Branch vs main: git diff main...HEAD
• Include untracked: append git ls-files --others --exclude-standard separately

Write the summary from step 1 verbatim to $SUMMARY_FILE using the Write tool.

Sanity check before invoking codex:

• If $DIFF_FILE is empty (no changes), tell the user there's nothing to review and stop.
• If the diff is enormous (>50k lines), warn the user — codex will still run but the review quality drops on huge surfaces. Suggest narrowing scope (e.g., per-file or per-phase review).

3. Run codex in headless review mode

codex exec \
  --sandbox read-only \
  --skip-git-repo-check \
  --color never \
  --output-last-message "$OUT_FILE" \
  "$(cat <<PROMPT
You are reviewing a working-tree diff produced by another coding agent (Claude).

You will receive two files:
- $SUMMARY_FILE — Claude's own summary of what it implemented and why
- $DIFF_FILE — the raw \`git diff HEAD\` output plus \`git status --short\`

Read both before reviewing.

You also have access to two skill methodology references (read them before forming your review — they describe what to look for):
- ~/.codex/skills/cmd-follow-up/SKILL.md — post-implementation reflection methodology (incomplete tasks, idiomatic concerns, modularity, simplification, comments/prose)
- ~/.codex/skills/cmd-pr-edgecase/SKILL.md — edge case and failure mode methodology (test gaps, malformed inputs, integration risks)

Apply BOTH methodologies to this diff. Then go further: look for issues those skills do not cover.

Your job:
1. **Correctness bugs** — logic errors, off-by-ones, wrong conditionals, race conditions, incorrect API usage. Cite file:line.
2. **Test gaps** — code paths added without tests, edge cases not covered, regression risks. Cite which test file should exist or be extended.
3. **Edge cases & failure modes** — what happens with empty input, null, concurrent calls, malformed data, network failure, partial state.
4. **Adjacent improvements** — things the diff touches that could be cleaned up in the same pass (dead code nearby, stale comments, naming inconsistencies).
5. **Simplification opportunities** — over-engineering, premature abstraction, defensive code for impossible states, dead branches.
6. **Idiomatic / convention violations** — where the diff diverges from the project's patterns (look at surrounding files in the diff for the local convention).
7. **What Claude likely missed** — read the summary critically. Did Claude defer something that actually matters? Claim test coverage that isn't there? Skip a constraint?
8. **What's good** — 1-3 honest bullets on what the implementation gets right. No flattery.

Constraints:
- Do NOT modify files. This is a read-only review.
- Be specific: cite \`file_path:line_number\` for every finding. Vague critique is useless.
- Rank findings by severity (critical / high / medium / low).
- If the implementation is solid, say so. Do not invent issues.

Output format (markdown):

## Verdict
One sentence: ship-as-is | minor-tweaks | needs-rework | blocked

## Critical / High
[bullets — bugs, missing tests for risky paths, broken invariants — with file:line]

## Medium
[bullets — edge cases, simplification opportunities, idiomatic concerns — with file:line]

## Low / Adjacent
[bullets — nice-to-haves, follow-up TODOs, stale-comment cleanup — with file:line]

## What Claude Likely Missed
[bullets called out from reading the summary against the diff]

## What's Good
[1-3 honest bullets]
PROMPT
)" < /dev/null

Stream codex's progress to the user as it runs. Capture the final review from $OUT_FILE.

Note: the prompt references $SUMMARY_FILE and $DIFF_FILE by absolute path. Since codex runs read-only in the same working directory, it will read those tempfiles when instructed. Use full paths in the heredoc (substituted by the shell) so codex can locate them without ambiguity.

4. Present codex's raw feedback

Show the contents of $OUT_FILE to the user verbatim under a heading:

## Codex review

> Independent review from `codex exec` — diff + summary only, no conversation context.

<contents of $OUT_FILE>

Do NOT paraphrase. The user wants codex's voice.

5. Synthesize an iteration plan

Read codex's findings and convert them into a concrete iteration plan. For each finding, decide:

• Apply now — fix in this iteration before commit
• Defer with TODO — legitimate but out of scope; add a TODO_TECHDEBT / TODO_IDEA comment in the relevant file
• Reject — wrong, irrelevant, or codex misunderstood context Claude has

Don't blindly accept everything. If a finding is wrong (codex missed context, misread the diff, or proposed something contrary to the project's conventions), mark it rejected and explain why.

6. Cleanup

rm -f "$DIFF_FILE" "$SUMMARY_FILE" "$OUT_FILE"

Codex prompt

The exact prompt is embedded in step 3. Key requirements when adapting it:

• Tell codex it's reviewing another agent's diff (sets tone)
• Point codex at the skill methodology files in ~/.codex/skills/ — those are symlinked to the repo and codex can read them in read-only mode
• Demand file:line references — vague critique is useless
• Force a verdict line for triage at a glance
• Allow codex to say "looks good" — no manufactured issues

Output format

After codex returns, present the result as three sections in order:

1. Codex's raw review

Quoted verbatim under a ## Codex review heading.

2. Iteration plan

Prioritized checklist Claude will execute (or propose to execute) next. Group by decision:

**Apply now (P0):**
- [ ] `path/to/file.py:42` — fix off-by-one in pagination loop
- [ ] `path/to/test_file.py` — add test for empty-list case

**Apply now (P1):**
- [ ] `path/to/other.py:88` — extract duplicated normalization helper

**Defer with TODO:**
- [ ] `path/to/file.py:120` — add `TODO_TECHDEBT` for connection pooling
      Why deferred: not blocking; needs separate evaluation of pgbouncer vs in-app pooling

**Rejected:**
- [ ] Codex suggestion: "Wrap entire handler in try/except"
      Why rejected: framework already converts exceptions to 500s; adding try/except would swallow stack traces

3. Changelog

Table summarizing every codex finding and what Claude decided:

S	Finding	Severity	Decision	Reason
🟢	Off-by-one in pagination at loader.py:42	High	Apply now	Genuine bug, codex caught it
🟡	Connection pooling	Medium	Defer	TODO_TECHDEBT added; out of scope
🔴	Wrap handler in try/except	Low	Reject	Framework handles it; would hide errors
🟢	Add empty-list test in test_loader.py	Medium	Apply now	Real gap, test is small

🟢 Apply now · 🟡 Defer (with TODO) · 🔴 Reject · ⚪ Already addressed

End with a one-line tl;dr: e.g., "3 fixes to apply, 1 TODO to add, 1 suggestion rejected. Verdict: minor-tweaks."

6. Ask before applying

After presenting the iteration plan, ask the user whether to apply the P0/P1 fixes now or wait. Don't auto-apply — the user wants to see the plan first.

Notes

• Codex needs auth — if codex exec errors with auth issues, tell the user to run codex login and stop.
• Read-only sandbox — codex cannot modify files even if it tries. This is intentional.
• Skill paths are symlinked — ~/.codex/skills/cmd-follow-up/SKILL.md resolves to this repo via make link-skills. If codex reports it can't read those paths, the user may need to run make link-skills from ~/workspace/agent-skills.
• Don't loop — one codex review per invocation. After applying fixes, the user can re-run for another pass if desired.
• Untracked files — git diff HEAD does NOT show untracked files. If the implementation added new files that aren't yet tracked, mention this to the user and offer to git add -N them so they appear in the diff (intent-to-add stages the path without content, making the diff include them).
• Companion skill — pair with cmd-codex-review-plan (pre-implementation plan review) for full coverage: codex reviews the plan before execution AND the diff after.