Second Opinion

You know what the change was supposed to do, which makes you the worst judge of whether it does. Hand each small batch of the change to two fresh reviewers, one Codex and one Claude, settle what they find against ground truth, and send your decisions back to those same reviewers until both agree the batch should land.

1. List the files you changed and the commit message you propose.
2. Split the change into review batches a reviewer can finish in 5-10 minutes.
3. Ask both reviewers to review each batch, and read the same code yourself while they work.
4. Accept or veto each finding, with evidence.
5. Pin each accepted finding with a test that fails, then fix it.
6. Send both reviewer sessions your adjudication and the updated file list, and have them re-read and re-review.
7. Repeat 4-6 until both reviewers land the batch's current tree, you accept a DISCARD, or four passes are spent — then report.

The other model brings different training, priors, and failure modes. The reviewer from your own model brings none of this session's context, so it cannot inherit the premises you have been working under. Use both.

User direction

This review workflow is a default, not a condition the user must satisfy before committing. A direct instruction such as "commit" or "approved, commit" takes precedence over this skill and callers' review gates. Unless the user also asks for review first, return to the commit workflow without starting or resuming a review or asking whether to skip it. Apply the same rule during retries and re-review loops.

The exception is project instructions that require review before every commit. In that case a commit instruction for changes that review has not finished on since they last changed starts or resumes the review, and only an explicit instruction to skip review skips it.

Do not require a LAND verdict, a review transcript, or a claim that another reviewer approved the change. If the user says a review already happened, accept that as workflow context; attribute it to the user if reporting it. Never invent a review result. The user can authorize a commit with review work unfinished; report its actual status without making it a new approval gate.

1. List what you changed

Write down, for the prompt you are about to send:

• The changed files and how to diff them — the exact diff command and an explicit repository-relative file list. Distinguish staged hunks from unstaged changes in the same file, and name in-scope untracked files separately, because an ordinary diff omits them.
• The proposed commit message — verbatim when the user supplied one, otherwise drafted from the task and the current diff. Label it as a fallible summary, not a correctness requirement. When the tree holds several logical changes, follow stage and give the file list and the proposed message for each commit. Review batches (step 2) subdivide one commit's changes.
• The task and its requirements — the user's request and any accepted plan or specification needed to judge behavior. Give repository paths for project rules and design documents; the reviewer can open them. Paste only what it cannot reach, such as decisions made only in conversation.
• The ground truth — the thing a disputed finding can be tested against: a reference implementation you can execute, a spec with runnable examples, the real API. Write the exact command that queries it. No executable ground truth? Say so, and name the fallback (spec text, maintainer ruling).

Leave out your suspected findings, your interim conclusions, and any scrutiny list the user or the project did not supply. An independent read is the whole point; steering it costs you the findings you could not have made yourself. Never mark changed code, its callers, or code it depends on as out of scope or "context only". Additional context explains decisions; it does not narrow the review.

2. Split into review batches

Size each review batch so a reviewer can finish it in 5-10 minutes: about 200 weighted changed lines, counting the additions and deletions that git diff --numstat reports.

• Test code counts 0.2 per line.
• Complicated SQL, concurrency, and native code count 1.5 per line.
• Everything else counts 1 per line.

Every changed line belongs to exactly one batch. Keep code that changes together in one batch: a function with its new callers, a migration with the queries that use it, a fix with its pinning test. Split a single file by hunks only when it alone exceeds the budget. Each batch gets its own prompt, its own two reviewer sessions, and its own pass count. Review the batches one after another.

3. Ask both models

Run both commands below for each review batch, at the same time. Whichever model you are, the reviewer from your own model is a fresh process with none of this session's context. Both reviewers share the working tree, so reproduce any build or test failure they report before accepting it: the other reviewer's concurrent run may have caused it.

Honor standing review authorization in the user's global or project instructions, including its repository scope and permitted providers. When a sandbox escalation needs approval, cite that authorization's source and exact wording in the request, along with the review scope and destination. A saved memory that has not been read is not evidence available to the approval reviewer. Do not ask the user to repeat authorization that already covers the action. This skill does not itself grant permission to disclose code, and standing authorization does not override a host-policy denial.

Both commands run under a supervisor that kills the reviewer after 15 minutes of silence and reaps its whole process group. The window is deliberately generous: a working review goes quiet for a couple of minutes at a stretch, and a review can run a slow build or test suite.

Write the complete reviewer prompt to a fresh UTF-8 temporary file with the host's file-writing tool. Do not interpolate supplied text into a shell command: commit messages and pasted context can contain quotes, dollar signs, backticks, or command substitutions. The supervisor replaces the exact {prompt} argument with the file's contents as one literal process argument. Delete the temporary file after the reviewer exits.

The Codex reviewer:

python3 "<this-skill>/scripts/run_with_idle_timeout.py" \
  --prompt-file "<prompt-file>" -- \
  codex exec \
  -C "<target-repository>" \
  --sandbox workspace-write \
  -c 'model_reasoning_effort="xhigh"' \
  --json \
  --output-last-message "<review-file>" \
  "{prompt}" \
  > "<events-file>"

workspace-write lets the reviewer run the project's typecheck, build, and tests to prove a finding. It can write inside the repository and the temporary directory; every other path is read-only and the network is off. When the project's tests write elsewhere or need the network, add -c 'sandbox_workspace_write.writable_roots=["<path>"]' or -c 'sandbox_workspace_write.network_access=true' to both Codex commands, as the project's guidance directs.

Begin the prompt file with $coding:review, including for a staged diff. Invoke plain codex exec, not the review subcommand: that substitutes Codex's built-in review prompt and cannot load this marketplace's skill. Name the diff range in the prompt itself — "the uncommitted changes", "the changes since <sha>". Codex needs the coding plugin installed:

codex plugin marketplace add photostructure/coding-skills
codex plugin add coding@photostructure

Do not pass --ephemeral: the session must remain resumable for the re-review. --output-last-message captures the clean review while the JSONL stream keeps the supervisor fed. After a clean exit, record the session ID:

jq -sr '[.[] | select(.type=="thread.started") | .thread_id] | last // empty' "<events-file>"

The Claude reviewer:

Run the command with the target repository as its working directory. Resolve <coding-plugin-root> to the plugin directory that contains this skill so the spawned process does not depend on user- or repository-scoped plugin settings.

python3 "<this-skill>/scripts/run_with_idle_timeout.py" \
  --prompt-file "<prompt-file>" -- \
  claude -p "{prompt}" \
  --plugin-dir "<coding-plugin-root>" \
  --permission-mode auto \
  --disallowedTools Edit Write NotebookEdit \
  --model opus \
  --effort xhigh \
  --output-format stream-json --verbose \
  > "<events-file>"

--permission-mode auto lets the reviewer run the project's typecheck, build, and tests, with Claude Code's classifier refusing risky commands. --disallowedTools removes the file-editing tools. --output-format stream-json is what keeps the supervisor fed — plain -p prints nothing at all until it finishes. Both the reasoning and the tool calls stream, so watch the file to see what the reviewer is chewing on. Extract the review after a clean exit:

jq -r 'select(.type=="result").result' "<events-file>"

Claude persists print-mode sessions unless --no-session-persistence is set. Do not set it. Record the session ID:

jq -sr '[.[] | select((.type=="system" and .subtype=="init") or .type=="result") | .session_id // empty] | last // empty' \
  "<events-file>"

Begin the prompt file with /coding:review, including for a staged diff. The -p prompt must begin with the slash command so Claude invokes the skill directly. An unavailable slash command is a plugin-loading failure even when Claude exits 0.

Use xhigh effort for both reviewers. Small batches keep each review short.

Claude.ai OAuth may need to rewrite its credential store when refreshing an expired token. On Codex hosts whose filesystem sandbox can read but not write ~/.claude, the command may return an expired-token 401 even though claude auth status reports logged in or the same command works in the user's terminal. In that specific case, retry the exact supervised command once with the host's narrow filesystem-sandbox escalation (sandbox_permissions: require_escalated where available) so Claude can refresh its existing credential. Do not read, print, copy, or manually rewrite the credential. If the escalated retry fails, use the unauthenticated fallback below.

These command shapes depend on Claude print-session persistence and --resume, and on Codex JSON events, --output-last-message, and exec resume. Revalidate them against a real diff when those CLI options change. Do not substitute a similarly named built-in review mode without the same validation.

After the skill invocation, the prompt file carries the step 1 inputs:

Review the batch below and return the full report to me, the calling agent. I
will accept or veto each finding and send you the results. Do not apply fixes,
and do not ask the user to adjudicate.

Diff command: <exact command, and any hunk limits>
Changed files:
<explicit list, marking in-scope untracked files>
This is review batch <n> of <m>. The other batches change: <files, or "none">.
Read them where they interact with this batch; they are reviewed separately.

Proposed commit message (fallible summary, not a requirement):
<complete message, or one per commit with its files>

Task and requirements: <text, or repository paths>
Additional context: <decisions made only in conversation, or "none">
Ground truth: <exact command, or the fallback>

Read the current diff and files from the repository. Review the full scope and
its interactions, and keep commit-message and grouping advice in Commit notes,
separate from the findings. You may run the project's typecheck, build, and
tests, or a reproducer in the temporary directory, to prove a finding. Do not
edit tracked files. Another reviewer is reviewing this checkout at the same
time and may build and test too: follow the project's shared-checkout rules,
do not clean or delete shared build outputs while another run may be using
them, and rerun any failure a concurrent run could explain before reporting it.

Name the review skill; never ask the reviewer to run second-opinion. If the spawned CLI cannot load the coding plugin, rerun it with the full text of ../review/references/single-pass.md pasted into the prompt instead of naming the skill.

Resolve <this-skill> to this skill's directory. Run both commands in the background and poll each job until it exits:

• 0 — read the review and record the CLI, repository, batch, session ID, pass count, and finding IDs in your task notes. Keep that handle through fixes and handoffs; never select a reviewer with --last or --continue, which can attach to unrelated work. A missing session ID does not invalidate the pass, but it forces the fresh-session fallback in step 6.
• 124 with the supervisor's idle timeout: diagnostic — the reviewer went silent for 15 minutes. Discard the partial review, say so, and finish your own pass.
• 124 without that diagnostic — the reviewer CLI itself returned 124. Report its status and finish your own pass; do not call it an idle timeout.
• a fast non-zero with a CLI usage or unknown-option diagnostic — the invocation is stale. Report it as a bug in this skill; never let it pass as "no issues found".
• 127 or an authentication error — for an expired Claude.ai OAuth error from Codex, use the one-time sandbox-escalation retry above. Otherwise, or if that retry fails, use the fallback below. These are environment failures, not bugs in this skill.
• 0 with an Unknown command, a missing-skill result, or a final review that does not begin with the required LAND, REVISE, or DISCARD verdict — the CLI did not run the shared method. Treat it as a plugin-loading failure, not a clean review, and use the pasted-method fallback above. Allow ordinary Markdown decoration around the verdict text.
• any other non-zero — report the status and finish your own pass.

Read the new code yourself while the reviewers run — you are the third reviewer, and the only one who knows the full context of what the change was supposed to do. Hold your edits until both reports arrive. The reviewers read the repository live, so a file that changes mid-pass gives them a tree that never existed. Write down what you find and adjudicate it in step 4.

If either CLI is not installed or not authenticated, say so plainly and run that reviewer as a task-local subagent of a model you can reach, given the same prompt and the full text of ../review/references/single-pass.md. Save its handle and send the follow-up prompts to that same subagent. Its findings count, but its verdict is not that model's verdict: the step 7 report marks that model's slot as missing.

4. Adjudicate every finding

First set aside every concern that is only about the commit message, or about grouping, splitting, or ordering otherwise-valid content. Those are commit notes, not findings: no severity, no accept, no veto, no pinning test. If they are all that any review raised, the verdict is LAND.

The verdict does not decide what you adjudicate. A LAND carrying findings still carries findings: settle every one. An empty findings list ends the work, not the word LAND.

Then settle each remaining finding — both reviewers' and your own. An Unexplained finding follows its own rule below. For every other finding:

1. Build the empirical test: run ground truth and the new code on the same input, and compare. A finding you cannot test this way becomes an open question, not a silent acceptance.
2. Accept only when ground truth confirms the bug.
3. Veto only when ground truth confirms the code is right, or the finding demands fidelity nothing requires — mirroring a reference implementation's internals on a path no contract pins, for instance.
4. When the diagnosis is right but the proposed fix is mediocre, take the better fix. Reviewers identify problems; you own the remedy.

An Unexplained finding means the reviewer could not say why an added or modified function or branch exists from the code, tests, documentation, and commit message. No ground truth settles it. Answer the reviewer's question instead:

• Veto when the answer is already in the code, tests, documentation, or commit message. Cite where.
• Accept when it is not, and put the answer there: a clearer name, a test, a comment, or the commit message. Simplifying the code until no answer is needed also settles it.
• If you cannot answer the question either, trace what the code does until you can, then accept or veto as above. A defect found this way is settled like any other finding.

Reviewer confidence, eloquence, and agreement between reviewers are not evidence. Two models converging on the same wrong finding is common; one command against ground truth beats both.

When two or more fixes are defensible and nothing chooses between them, ask the user. Give the finding, each alternative with its tradeoff, and your recommendation if you have one, then wait for direction. Ground truth settles whether the code is wrong; it usually does not settle which correct design to adopt, and that choice is the user's.

Your own context of settled decisions and corrected premises catches plausible-but-wrong findings a fresh reader cannot — that is why you adjudicate. It can also contain the defect: a wrong premise this session has carried since birth, which is exactly what the independent pass is for. So a veto of yours carries no special weight. It needs the same recorded evidence as anyone's.

5. Pin, then fix

Every accepted finding gets a pinning test whose expected values come from ground truth; paste the command that produced them into the test's comment. Run it against the unfixed code and confirm it fails, then apply the fix. An accepted Unexplained finding whose fix changed no behavior — a rename, a comment, or a commit-message change — needs no pinning test. Every test the fixes could affect must pass again, not just the new pinning tests.

6. Re-review in the same sessions

Continue this loop only while review remains in scope under User direction.

Send your adjudication to both of the batch's reviewers, even when you vetoed everything and changed no code. If you applied fixes, wait until every test they could affect passes. Re-read the complete current scope yourself, and ask each reviewer to do the same:

Re-read and re-review the complete current scope from the repository, then
return the normal verdict and findings. Do not rely on what you read last pass,
and do not limit the review to the fixes.

Author notes:
Accepted <ID>: <diagnosis, the fix and its location, how it was validated>
Vetoed <ID>: <the concrete evidence that the code is right>
Open <ID>: <what is still unsettled, and what would settle it>

Files now in play: <updated file list, including files the fixes touched>
Proposed commit message: <current complete message>
Changed requirements or ground truth: <updates only, or "unchanged">

Keep existing finding IDs and give new issues new IDs. Report each prior
finding as resolved, still present, or disputed. If you think a veto is wrong,
say what evidence would settle it. Do not apply fixes, and do not ask the user
to adjudicate.

Use none for an empty list. Do not repaste requirements the session already has. Include findings from your own read when they explain a fix.

Resume the recorded session in the same repository, through the same supervisor, with its exact session ID. Do not fork it or start a new session for an ordinary follow-up. For a Claude reviewer:

python3 "<this-skill>/scripts/run_with_idle_timeout.py" \
  --prompt-file "<follow-up-prompt-file>" -- \
  claude -p "{prompt}" \
  --resume "<session-id>" \
  --plugin-dir "<coding-plugin-root>" \
  --permission-mode auto \
  --disallowedTools Edit Write NotebookEdit \
  --model opus \
  --effort xhigh \
  --output-format stream-json --verbose \
  > "<next-events-file>"

For a Codex reviewer:

python3 "<this-skill>/scripts/run_with_idle_timeout.py" \
  --prompt-file "<follow-up-prompt-file>" -- \
  codex exec \
  -C "<target-repository>" \
  --sandbox workspace-write \
  resume \
  -c 'model_reasoning_effort="xhigh"' \
  --json \
  --output-last-message "<next-review-file>" \
  "<session-id>" \
  "{prompt}" \
  > "<next-events-file>"

Apply the same exit-status and output-validity checks as the first pass. If the CLI cannot resume the recorded session, launch a fresh one with the original prompt updated for the current scope, plus the prior report, its finding IDs, and every accept and veto with its evidence. Record the replacement handle and disclose that continuity was unavailable. A resume failure does not justify skipping the re-review.

Then return to step 4 for the new reports. Stop when both reviewers return LAND on the batch as it now stands and every finding from all three reads is either accepted and fixed or vetoed with evidence. A LAND does not cover code you changed after that reviewer's last read: if adjudication changed the tree, run one more pass, subject to the cap. Stop earlier when you adjudicate a DISCARD as correct — the change should not land at all. Preserve that verdict and report it; do not re-review a settled decision.

Stop at four review passes per batch either way. If the fourth leaves accepted fixes or disputed findings, finish the authorized fixes and tests, then report the cap and what is still unsettled; do not describe unreviewed fixes as a clean pass. Skip the loop entirely when the first pass raised nothing substantive and no code changed.

7. Report the verdicts

Summarize for the user (and for whatever plan or PR document tracks this work): every substantive finding, accepted and vetoed, with one-line evidence for each verdict, and which model raised it. Record vetoes especially — the next session will rediscover the same "bug" and must not re-litigate it.

Begin with one top-level Verdict: LAND | REVISE | DISCARD line, then one line per review batch with its files, its pass count, and each model's final verdict: Batch 2 (src/a.ts, src/a.spec.ts): 2 passes; Codex LAND, Claude LAND. Only a reviewer launched through that model's CLI fills its slot. Otherwise write why the slot is empty, for example Codex missing (CLI not installed; Claude subagent LAND) or Claude missing (idle timeout). Project policy may act on these lines. If no review raised a substantive finding, use LAND, follow it with No issues found., and do not invent ledger rows. Otherwise list the accepted and vetoed findings under their original IDs, even when the final verdict is LAND, and state any unresolved questions or unreviewed fixes separately.

The ledger repeats the final verdict in each row so a copied or aggregated row still reads correctly:

ID	Scope	Model	Finding	Severity	Accept/Veto	Evidence (one line)	Verdict

After the ledger — or after No issues found. when there are no rows — add a brief Commit notes section when either model proposed a warranted message or grouping improvement. Name the model, state the specific reason, and give the complete improved message. For a split, identify every independently committable group and give each group's complete message. These notes have no severity and cannot change the verdict.

Scratch files

Any copy this workflow makes — of the repo, of a build-output directory, of a file you replay edits onto — belongs in the operating system's temporary directory, in a fresh directory named for the project and the purpose. Never inside the checkout, and never under a home directory.

Delete it before you finish. A repo or build-output copy runs to gigabytes, nothing reaps a home directory, and the out-of-disk failure that eventually follows surfaces somewhere unrelated — a test suite that hangs, a build that dies mid-link — costing far more to diagnose than the copy ever saved.

Adapting for your project

• Name the ground truth explicitly — e.g. "the vendored reference implementation via ./third-party/tool/run", "CPython 3.12 via uv run python -c ...", "the RFC's test vectors". Step 4 is only as strong as this.
• Say how to name the diff range the way your project talks about it — "the changes on this branch vs develop", "everything since the last tag".
• Optional review focus belongs in project guidance. Keep it a starting point; the reviewers still examine the full scope independently.
• Name sandbox needs: paths outside the repository that the project's tests write, and whether they need the network, so callers add them to the Codex commands.
• Callers welcome: other skills (gitplan, tpp-orchestrate) reference this file as their review gate. Keep the gate generic here; put workflow-specific bookkeeping (where verdicts get recorded, commit conventions) in the calling skill.