Find bugs with ultrareview changedultrareview
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77> Ultrareview is a research preview feature. The feature, pricing, and availability may change based on feedback. The command is `/code-review ultra`. When ultrareview is available to your account, `/ultrareview` is an alias.
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9Ultrareview is a deep code review that runs as a [cloud session](/docs/en/claude-code-on-the-web) on Anthropic's infrastructure. When you run `/code-review ultra`, Claude Code launches a fleet of reviewer agents in a cloud sandbox to find bugs in your branch or pull request.
9Ultrareview is a deep code review that runs as a [cloud session](/docs/en/claude-code-on-the-web.md) on Anthropic's infrastructure. When you run `/code-review ultra`, Claude Code launches a fleet of reviewer agents in a cloud sandbox to find bugs in your branch or pull request.
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1111Compared to a local `/code-review`, ultrareview offers:
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1414* **Broader coverage**: a larger fleet of reviewer agents explores the change in parallel, which surfaces issues that a local review can miss
1515* **No local resource use**: the review runs entirely in a cloud sandbox, so your terminal stays free for other work while it runs
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17Ultrareview requires authentication with a claude.ai account because it runs as a cloud session on Anthropic's infrastructure. If you are signed in with an API key only, run `/login` and authenticate with claude.ai first. Ultrareview is not available when using Claude Code with Amazon Bedrock, Google Cloud's Agent Platform, or Microsoft Foundry, and it is not available to organizations that have enabled Zero Data Retention or have the [HIPAA configuration](/docs/en/hipaa-setup) applied. In these cases, `/code-review ultra` runs a local review in your session instead. Organizations that use [customer-managed encryption keys](https://platform.claude.com/docs/en/manage-claude/cmek) (CMEK) can't run ultrareview. To review your changes locally, run `/code-review`.
17Ultrareview requires authentication with a claude.ai account because it runs as a cloud session on Anthropic's infrastructure. If you are signed in with an API key only, run `/login` and authenticate with claude.ai first. Ultrareview is not available when using Claude Code with Amazon Bedrock, Google Cloud's Agent Platform, or Microsoft Foundry, and it is not available to organizations that have enabled Zero Data Retention or have the [HIPAA configuration](/docs/en/hipaa-setup.md) applied. In these cases, `/code-review ultra` runs a local review in your session instead. Organizations that use [customer-managed encryption keys](https://platform.claude.com/docs/en/manage-claude/cmek) (CMEK) can't run ultrareview. To review your changes locally, run `/code-review`.
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1919## Run ultrareview from the CLI
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2727Without arguments, ultrareview reviews the diff between your current branch and the default branch, including uncommitted and staged changes.
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29For a branch review, Claude Code bundles the repository state and uploads it to a cloud sandbox under the rules for [uploading a local repository to a cloud session](/docs/en/claude-code-on-the-web#send-local-repositories-without-github), which cover the size limits, the checkout requirements, and what happens to uncommitted changes in files named like credentials or keys, such as `.env` and `*.tfvars` files. When you [review a pull request](#review-a-pull-request), Claude Code uploads nothing from your machine.
29For a branch review, Claude Code bundles the repository state and uploads it to a cloud sandbox under the rules for [uploading a local repository to a cloud session](/docs/en/claude-code-on-the-web.md#send-local-repositories-without-github), which cover the size limits, the checkout requirements, and what happens to uncommitted changes in files named like credentials or keys, such as `.env` and `*.tfvars` files. When you [review a pull request](#review-a-pull-request), Claude Code uploads nothing from your machine.
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3131Before launching, Claude Code shows a confirmation dialog with the review scope, your remaining free runs, and the estimated cost; for a branch review, the scope includes the file and line count. After you confirm, the review continues in the background while you keep using your session.
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5555The command also accepts `#1234`, `PR 1234`, and pasted PR URLs; a pasted URL must point to the repository in your current directory.
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57PR mode needs a repository on `github.com`. For a repository on a [GitHub Enterprise Server](/docs/en/github-enterprise-server) instance, run `/code-review ultra` without a PR number to review your local branch instead.
57PR mode needs a repository on `github.com`. For a repository on a [GitHub Enterprise Server](/docs/en/github-enterprise-server.md) instance, run `/code-review ultra` without a PR number to review your local branch instead.
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5959In PR mode, the cloud sandbox clones the pull request from `github.com` instead of uploading your working tree. It uses the GitHub account connected to your Claude account, so that account needs read access to the repository.
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100100Ultrareview checks the diff before any review work runs and tells you when it can't review it as-is:
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102* **Diff too large**: a branch review can include up to 500 changed files and 8,000 changed lines by default. The exact values can change, and the [refusal](/docs/en/errors#diff-is-too-large-for-ultrareview) names the ones in effect, the size of your diff, and the files with the most changed lines. Claude Code refuses a too-large pull request the same way, naming its file and line counts but not the per-file breakdown
102* **Diff too large**: a branch review can include up to 500 changed files and 8,000 changed lines by default. The exact values can change, and the [refusal](/docs/en/errors.md#diff-is-too-large-for-ultrareview) names the ones in effect, the size of your diff, and the files with the most changed lines. Claude Code refuses a too-large pull request the same way, naming its file and line counts but not the per-file breakdown
103103* **Nothing to review**: when the diff against the base is empty, ultrareview refuses and names the branch or commit it compared against and the case you're in, such as being on the base branch itself with nothing uncommitted, or a branch whose commits are all part of the base already. It also suggests the way out for that case, such as switching to the branch with your work, staging or committing local edits, or passing a different base
104104* **First commit**: a repository's first commit has nothing earlier to compare with, so ultrareview reviews every file in it after you confirm in the launch dialog. If you have untracked files, it refuses instead and tells you to `git add` the ones you want reviewed. The same size limits apply.
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106106 A first commit is reviewed whole only after that confirmation, so the `claude ultrareview` subcommand and `claude -p` refuse it and point you to an interactive session instead. Requires Claude Code v2.1.277 or later
107107* **No merge base**: when your branch shares no history with the base branch, or the repository has no base branch to compare with, ultrareview reviews every tracked file in the repository instead. The fallback requires a full clone and applies the same size limits. It launches only when you confirm in the launch dialog or run the `claude ultrareview` subcommand yourself. In `claude -p` and anywhere else neither happens, ultrareview refuses, says the review would cover every file, and points you to an interactive session.
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109 On a checkout with no branches or other refs, such as a detached HEAD created by checking out `FETCH_HEAD` after fetching a URL, Claude Code [refuses the review](/docs/en/errors#your-checkout-has-no-branches) and suggests creating a branch first
109 On a checkout with no branches or other refs, such as a detached HEAD created by checking out `FETCH_HEAD` after fetching a URL, Claude Code [refuses the review](/docs/en/errors.md#your-checkout-has-no-branches) and suggests creating a branch first
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111111## Pricing and free runs
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136136Claude can also tell you that a review was stopped or that its session wasn't found:
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138* If the review's cloud session is stopped or [archived](/docs/en/claude-code-on-the-web#archive-sessions) on claude.ai before the review finishes, Claude tells you it was stopped.
138* If the review's cloud session is stopped or [archived](/docs/en/claude-code-on-the-web.md#archive-sessions) on claude.ai before the review finishes, Claude tells you it was stopped.
139139* If the review's cloud session was deleted, or you've signed in to a different Claude account or organization since launching it, Claude tells you the session wasn't found.
140140* If you switched accounts, the review may still finish under the account that started it. If the review is still running, sign back in as that account and resume the conversation with `claude --resume` to re-attach it.
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181181* If the run fails, is stopped, or times out, the subcommand posts nothing.
182182* If the review completes but the comment isn't posted, Claude Code prints the reason to stderr, and the findings stay on stdout so you can post them by hand.
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184For automatic reviews on GitHub pull requests, [Code Review](/docs/en/code-review) integrates with your repository directly and posts findings as inline PR comments without a CLI step.
184For automatic reviews on GitHub pull requests, [Code Review](/docs/en/code-review.md) integrates with your repository directly and posts findings as inline PR comments without a CLI step.
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186186## How ultrareview compares to /code-review
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201201## Related resources
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203* [Use Claude Code in the cloud](/docs/en/claude-code-on-the-web): learn how cloud sessions and cloud sandboxes work
204* [Manage costs effectively](/docs/en/costs): track usage and set spending limits
203* [Use Claude Code in the cloud](/docs/en/claude-code-on-the-web.md): learn how cloud sessions and cloud sandboxes work
204* [Manage costs effectively](/docs/en/costs.md): track usage and set spending limits
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