Anthropic's Claude Code Team Scales Code Review as Pull Requests Double

Anthropic's Claude Code team now routes every pull request through an AI review first. Merged PRs more than doubled from June to September, while the share of changes that had to be reverted fell by more than 40%. Required human approvals now scale with each change's risk.

Anthropic's Claude Code team has reworked its code review process to keep up with a surge in AI-generated changes. From June to September, merged pull requests to Claude Code's codebase more than doubled, while the share that had to be reverted fell by more than 40 percent, according to a post on claude.dev published Thursday, Oct. 15.

The pressure reaches well beyond one team. In Anthropic's monorepo, changes landing per day rose from about 2,500 in May to more than 30,000 in September. Claude Code lives in its own repository, separate from the monorepo, but the post says it is seeing a lot of pressure too.

At that pace, manual line-by-line review is "incredibly difficult if not impossible," the authors wrote. Once the team had high coverage and deep reviews in place, it started optimizing for the minimum amount of human review time that doesn't raise reverts or incidents.

Every pull request now gets a review from Claude before a person looks at it. The model reads the diff against the whole repo and the PR's stated intent, and checks whether the change solves its problem, fits the system or breaks something else. On a bug fix, it looks for the root cause.

A public version, Code Review for Claude Code, is now generally available on Team and Enterprise plans, and the /code-review command runs a lighter version locally. When Anthropic launched the research preview, the share of internal pull requests getting substantive review comments rose from 16% to 54%.

Human approval is scaled by risk. Docs, copy and additive changes behind a flag need no human approval once automated review and security checks are green, ordinary product changes need one person, and the highest-risk code needs two. A classifier sets the tier from the change rather than the author, and an agent's approval never counts as a person's. A PR also can't merge while any finding from the bug review or a separate automated security review is still open.

Anthropic has rebuilt its source control to handle the volume as well. In a separate engineering post published Tuesday, Oct. 13, the company described Scion, an in-house version control system, and a code review tool called Antique. A team of seven built both, plus half a dozen related systems, and fully migrated the monorepo from Git in five months. That team still reviews every change request for Scion, but its members now examine the intent of a change instead of reading every line.

Anthropic's reviews have let bugs through before. In an April 23 postmortem on Claude Code quality complaints, the company traced the reports to three separate changes, all resolved as of April 20 in v2.1.116. One of them, a caching bug that kept clearing Claude's older reasoning from sessions that had been idle for over an hour, made it past multiple human and automated code reviews. When Anthropic back-tested Code Review against the offending pull requests, Opus 4.7 found the bug once it had the code repositories it needed for full context, and Opus 4.6 didn't. Anthropic said it was landing support for additional repositories as context for code reviews.