review-diff

name	review-diff
description	Generate a Markdown review file with C4 architecture diagrams and code walkthrough for the current git changes
allowed-tools	Bash(git *), Bash(mkdir *), Read, Glob, Grep, Write, Edit

PR Review Markdown Generator

Generate a Markdown review file for the current uncommitted git changes (or a specified PR). Save it to .review/review.md.

What to produce

The file must contain three sections:

1. System Architecture Diagram (C4 Container Level)

A single Mermaid flowchart showing the system architecture with the changed/new components highlighted:

• Use flowchart TD (top-down) for the diagram
• Show the request flow from user through frontend to backend
• Group unchanged peer components into a single summary node (e.g. "Other 5 scenarios")
• Highlight changed components with dark green fill/border for dark theme: fill:#0d3320,stroke:#238636,stroke-width:3px,color:#aff0b5
• Highlight new components with dark green fill/border and a green circle emoji prefix: fill:#0d3320,stroke:#238636,stroke-width:3px,color:#aff0b5
• Highlight data sources read by new code with dark blue: fill:#0d2044,stroke:#388bfd,stroke-width:2px,color:#79c0ff
• Include a legend below the diagram

2. Component Detail Flowchart

A Mermaid flowchart showing the internal logic flow of the changed component:

• Show the decision tree / branching logic
• Mark new code paths with dark green and green circle emoji: fill:#0d3320,stroke:#238636,stroke-width:2px,color:#aff0b5
• Mark removed paths with dark red dashed and red circle emoji: fill:#3d0f14,stroke:#da3633,stroke-width:2px,stroke-dasharray:5 5,color:#ffa198
• Mark unchanged paths with dark grey: fill:#1c1c1c,stroke:#555,color:#aaa
• Add a description table below the diagram explaining each node

3. Code Walkthrough

For each logical chunk of the change:

• A narrative paragraph explaining what the code does and why
• An inline diff block using standard markdown diff syntax (```diff)

Diagram guidelines

Keep Mermaid node labels SHORT (under 25 characters) to prevent text truncation. Use the description table below each diagram for detailed explanations. Avoid \n for line breaks in labels — use single-line text or unicode separators like · or ‹›.

Always include this Mermaid init for dark theme rendering:

%%{init: {'theme': 'dark', 'flowchart': {'useMaxWidth': true}} }%%

Steps

1. Run git diff HEAD and git diff --stat HEAD to understand the changes
2. Read the changed files and their surrounding architecture (imports, callers, class hierarchy)
3. Create .review/ directory if it doesn't exist
4. Generate .review/review.md with all three sections
5. Verify the Mermaid code blocks are well-formed and node labels are under 25 characters

Arguments

• $ARGUMENTS — optional: a git ref, PR number, or branch name to diff against (defaults to uncommitted changes vs HEAD)