How do I review diagrams in pull requests?

Store diagrams as Mermaid or PlantUML code in your repository. When a diagram is changed on a branch, the pull request shows a text diff of exactly what changed — new components, modified relationships, removed services. GitHub also renders Mermaid in Markdown preview.

Can GitHub render Mermaid in pull requests?

Yes. When Mermaid code is embedded in a Markdown file (```mermaid blocks), GitHub renders it as a visual diagram in the PR file preview. Reviewers see both the code diff and the rendered diagram.

How does this improve architecture reviews?

Instead of reviewing a screenshot or slide, reviewers see a precise diff showing what changed. They can comment on specific lines, require approval from architecture leads, and link changes to tickets. Every decision has an audit trail.

Diagrams in Pull Requests

Review architecture in PRs

Architecture changes deserve the same review process as code changes. Diagram diffs in pull requests — see exactly what changed, comment on specific lines, and approve with confidence.

Start reviewing diagrams →Diagrams in Git

Architecture changes need review

You wouldn't merge a major code change without review. Why do architecture changes bypass review entirely? When diagrams live on whiteboards or in Lucidchart, there's no formal review process — someone updates the diagram and hopes the team notices.

With diagram-as-code, architecture changes go through the same pull request workflow as code: branch, commit, open PR, review, merge. The diff shows exactly what changed — a new service, a removed dependency, a renamed database.

Cybewave generates the Mermaid & PlantUML code from plain English so your team can focus on reviewing the architecture, not the syntax.

Workflow

Same PR workflow you already use, applied to architecture.

Branch for changes

Create a feature branch for your architecture change — just like any code change.

Update diagram code

Edit the Mermaid or PlantUML source, or use Cybewave AI to regenerate from an updated description.

Open a pull request

The diff shows exactly which components, relationships, or labels changed. Mermaid renders in the PR preview.

Review and merge

Team reviews the architecture change with full context: commit message, linked issues, and visual diff.

Benefits

Architecture review with the same rigor as code review.

Text diffs for architecture

See exactly what changed: a new service added, a database renamed, a relationship removed. No comparing screenshots.

Comment on specific changes

PR reviewers can comment on specific lines: "Why does the order service talk directly to the payment DB?"

Link to context

Architecture changes are linked to tickets, features, and discussions. Six months later, the PR explains why.

Approval workflow

Require architecture reviews from senior engineers. Same CODEOWNERS rules you use for critical code paths.

Mermaid preview in PR

GitHub and GitLab render Mermaid in Markdown preview. See the actual diagram, not just the code, in the PR.

CI validation

Run diagram linting in CI. Catch syntax errors before they land. Auto-render updated diagrams on merge.

What a diagram diff looks like

Clear, reviewable changes — not "I updated the architecture."

 graph TD
   Client --> Gateway[API Gateway]
   Gateway --> Auth[Auth Service]
   Gateway --> Orders[Order Service]
   Orders --> DB[(PostgreSQL)]
+  Orders --> Cache[(Redis Cache)]
+  Orders --> Queue[RabbitMQ]
+  Queue --> Notifications[Email Worker]
-  Orders --> Legacy[Legacy Monolith]

Added Redis cache and async notifications. Removed legacy monolith dependency.

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