Graphite Agent is the AI reviewer inside Graphite, a code review platform that also handles stacked pull requests and a merge queue. If you searched for Graphite Diamond, this is the same product: in October 2025, Graphite merged Diamond and its Chat feature under the Graphite Agent name. It comments on GitHub pull requests about logic bugs, edge cases, security vulnerabilities, and performance problems.
Design Bug Bot, made by 21st, reviews the UI side of those same pull requests: whether new interface code reuses your components and follows your tokens, spacing, and type scale. Use Graphite Agent for code correctness in a stacked workflow; add Design Bug Bot when small, correct PRs keep adding up to an interface that drifts from your design system.
Disclosure: This page comes from 21st, the company behind Design Bug Bot. Every Graphite detail below is taken from Graphite's docs, pricing page, and blog as they read on September 14, 2026. It compares documented workflows and is not a benchmark; we have not tested both reviewers on the same pull requests.
Graphite Agent vs Design Bug Bot at a glance
| Topic | Graphite Agent | Design Bug Bot |
|---|---|---|
| Where it works | Inside Graphite, next to stacked PRs, a PR page, and a merge queue. Graphite | A GitHub App; results in GitHub and as a full review in 21st |
| What it flags | Logic bugs, edge cases, security vulnerabilities, performance issues, accidentally committed code. Review comments | Component reuse, tokens, spacing, type scale, layout risks, unnecessary dependencies |
| Reference | Context from your entire codebase, plus rules you write. AI reviews | Your repository's existing components, tokens, spacing, and type scale |
| Design conventions | Through custom rules; Graphite's own example asks for design system tokens instead of hex colors. Customization | The main subject of the review |
| Rendered UI evidence | Not described in the AI review docs checked | Desktop and mobile screenshots when the isolated render succeeds; code-backed recommendations when it cannot |
| Fix format | Line comments with a suggestion you can commit. Review comments | Suggested fix code in one review comment that updates with the PR; can push a branch for a fix PR |
| Scope controls | Filters by author, paths, labels, title, and parent branch; generated files skipped via .gitattributes. Customization | Only repositories you enable; PRs with no UI files get a neutral check and no comment |
| Pricing model | Per user; unlimited AI reviews on Team and Enterprise. Pricing | 5 free successful reviews, then AI credits. Details |
What Graphite Agent does well
Graphite Agent fits a workflow built around small pull requests. Graphite's home page describes breaking larger PRs into smaller, sequenced changes that a stack-aware merge queue lands in order, and once AI reviews are enabled for a repository, the agent reviews every new pull request in it. Graphite, setup
Its comments are structured for action: each describes the problem, explains why it matters, and offers a concrete fix you can commit like a teammate's suggestion. Review comments
Customization is detailed and measurable. Custom prompts live in the Rules & exclusions tab, with templates for language style guides, security, and accessibility standards. File-based rules point the agent at documents in your repository through glob patterns, comment exclusions switch off unwanted feedback, and each rule reports issues found and acceptance rate. Customization Chat, now part of the same agent, helps fix CI failures from the PR page. Graphite
On naming: Graphite retired the Diamond name on October 7, 2025 (announcement). On December 19, 2025, it announced a definitive agreement to join Cursor, saying it will continue to operate as an independent product and plans to combine its AI reviewer with Cursor's Bugbot. Graphite blog
Where Design Bug Bot differs: a stack of correct PRs that drifts
Graphite's docs show that design rules are possible. Their customization guide rewrites a vague stylesheet rule as "Never use hex color values directly, always use design system tokens instead." Add that rule and Graphite Agent will review against it.
Now take a three-PR stack for a settings page. The first adds a SettingsCard that re-creates the existing Card with its own border, radius, and padding. The second sets section headings at a pixel size between two steps of your type scale. The third adds a toolbar that hides its secondary actions at phone width. Each PR is small, logically correct, and free of raw hex values, so the token rule has nothing to flag.
Covering the rest with rules means writing down your type scale, every reusable component and when to use it, and your responsive constraints, then keeping that text current. Graphite's docs note that large rule files are truncated and too many files can reduce review quality. Customization
Design Bug Bot treats the repository itself as the reference. It reviews changed UI code against the components, tokens, spacing, and type scale already in the codebase, and looks for layout risks such as horizontal overflow, fixed widths, and actions hidden on mobile. For the SettingsCard, the finding it is built to produce explains the problem, points to the file and line when available, and includes suggested fix code that uses the existing Card. When the isolated render succeeds, the review can add desktop and mobile screenshots; otherwise, findings arrive as code-backed recommendations.
It does not review backend code, logic, or security, it does not block merges, and it runs only on GitHub, for React codebases with Tailwind or plain CSS.
Choosing or combining the two reviewers
Every PR in the stack passes review. Graphite Agent answered its question for each PR. Design Bug Bot reviews the UI files in each one, and it can also review recent changes on the default branch after a chosen number of commits or on a schedule, giving you a pass over the stack once it lands.
You already have a token rule in Graphite. Keep it; it is specific and cheap to maintain. Leave what a text rule handles poorly, such as which existing component fits and whether the layout holds at mobile width, to the design review.
A backend PR lands in the same repository. Design Bug Bot gives PRs without UI files a neutral check and no comment, so the reviewers do not overlap. Graphite Agent does the review.
Graphite pricing
Listed on Graphite pricing on September 14, 2026:
- Hobby: free, with limited AI reviews on personal account repositories.
- Starter: $20 per user per month, billed annually, with limited AI reviews and all GitHub organization repositories.
- Team: $40 per user per month, billed annually, with unlimited AI reviews, AI review customizations, and the merge queue.
- Enterprise: custom pricing.
For Design Bug Bot's free reviews and AI credit billing, see the trial and billing details.
A one-stack trial
- Choose a recent stack that touched UI and list what design review raised later: a duplicated component, an off-scale heading, a layout that broke on a phone.
- Write one Graphite custom rule for your tokens in the format its docs recommend (rule, bad example, good example, reasoning), and watch its acceptance rate on the Rules & exclusions tab.
- Enable Design Bug Bot on the same GitHub repository before the next UI stack, and note which findings came with screenshots.
- After the stack lands, compare the reviewers by fixes merged without rework.
For a manual pass to pair with either reviewer, use the React UI code review checklist; for the Cursor side, see Cursor Bugbot vs Design Bug Bot. Open Design Bug Bot
Frequently asked
- Is Graphite Diamond the same as Graphite Agent?
- Yes. On October 7, 2025, Graphite unified Diamond, its AI reviewer, with Graphite Chat and renamed the combined product Graphite Agent, retiring the Diamond name. Older articles about Diamond describe the reviewer that is now part of Graphite Agent.
- Can Graphite Agent enforce design tokens?
- It can follow a rule you write. Graphite's customization docs use a hex color rule as an example and suggest phrasing it as always using design system tokens. Custom prompts go in the Rules & exclusions tab, and file-based rules point to docs in your repository. The AI review docs we checked do not describe rendering the UI.
- Can Graphite Agent and Design Bug Bot comment on the same pull request?
- Both post to GitHub pull requests, so a team can enable both on one repository. Graphite Agent leaves line comments with suggested fixes. Design Bug Bot updates one review comment, posts a check for each reviewed commit, and gives PRs with no UI files a neutral check and no comment.
- Which Graphite plans include unlimited AI reviews?
- On September 14, 2026, Graphite's pricing page listed unlimited AI reviews on the Team and Enterprise plans, while Hobby and Starter had limited AI reviews. The Team plan also listed AI review customizations and the merge queue.