Get a second-opinion review from a fresh session or another model
Review the agent's diff in a session that didn't write it, either a fresh Claude Code session or Codex on the PR, and act only on findings that affect correctness.
Tools used
- Claude CodeWrites the change; a fresh session or subagent reviews it
- CodexOptional cross-model review on the GitHub PR
Step navigator
A review from a reviewer without the author's context, with the correctness issues fixed.
Developers merging agent-written code.
Before you start
On r/ClaudeAI, developers who have Claude Code write their code describe two review habits: a second, adversarial session that reads the diff cold, or Codex reviewing the PR. Both rest on the same idea: the reviewer shouldn't be the author.
Step-by-step instructions
Review in a context that did not write the code
"Just a second Claude Code session with the diff as context and instructions to be adversarial. Two sessions of the same model catch more than you'd think because the second one doesn't have the sunk-cost bias of having written the code." Anthropic's guide says the same: "A fresh context improves code review."
Review the diff on this branch against PLAN.md. Report only gaps that affect correctness or the stated requirements: missing edge cases, untested paths, changes outside scope. Cite file and line.
Why this works
The author session is biased toward its own code.
Or ask Codex to review the PR
Some developers add a different model for the important changes. With the repo connected to Codex, comment @codex review on the PR, or turn on automatic reviews in Codex settings; it follows guidance in AGENTS.md. A developer running parallel streams: "Codex reviewing Opus's work caught things Opus missed on its own."
@codex review
Tell the reviewer what counts as a finding
Anthropic warns: "A reviewer prompted to find gaps will usually report some, even when the work is sound". Tell it to flag only correctness and requirement gaps, and treat the rest as optional.
Why this works
Chasing every finding leads to over-engineering.
Feed the findings back to the writing session
Paste the review into the session that wrote the code, have it fix the real issues, and re-run the tests. Anthropic's Writer/Reviewer example is exactly this loop.
Here's the review feedback: <paste>. Fix the correctness issues, skip the style notes, and run the test suite.
End of guide · Reviewed Oct 26, 2026
Pro tips2
- Claude Code's bundled /code-review skill reviews the current diff in a fresh subagent.
- Write your review rules in AGENTS.md so Codex follows them.
Common mistakes2
- Asking the session that wrote the code to review it.
- Fixing every nit a reviewer raises.
FAQ2
Same model or a different one?
Does Codex review need setup?
Related field guides.
CodingRun parallel Claude Code agents in git worktrees without merge hell
Give each agent its own worktree, scope tasks so their files do not overlap, merge one stream at a time, and rebase the rest on the new main.
CodingMake a coding agent write the failing tests first, then implement
Split the work into separate prompts: tests only, confirm they fail for the right reason, commit, then implement without touching the tests.
CodingSet up Claude Code hooks for formatting, tests and protected files
Add PostToolUse hooks that format and test after edits, a PreToolUse hook that blocks protected files, and a notification for long runs.