---

name: codebase description: "Understand a GitHub repository by analyzing its PR history, architecture, and evolution patterns." argument-hint: "<owner/repo> [prs|notable|<pr-number>|area:<path>]" allowed-tools: Bash, Read

Codebase

Understand a GitHub repository through its PR history and structure.

Arguments

Parse $ARGUMENTS to determine the command:

• <owner/repo> alone → overview
• <owner/repo> prs → list PRs
• <owner/repo> notable → find high-signal PRs
• <owner/repo> <number> → deep dive into PR
• <owner/repo> area:<path> → PRs touching a path

Commands

Overview (default)

When only <owner/repo> is provided:

1. Fetch repo info:

gh repo view <repo> --json description,primaryLanguage,stargazerCount,forkCount

2. Fetch last 30 merged PRs:

gh pr list -R <repo> --state merged --limit 30 --json number,title,author,files,mergedAt

3. Analyze and report:
   • Repository description and stats
   • Most active directories (count file changes by directory)
   • Top contributors (count PRs by author)
   • Recent activity themes (categorize PR titles)

List PRs

When prs is specified:

gh pr list -R <repo> --state merged --limit 20 --json number,title,author,files,comments,mergedAt

Format as a table:

#     Title                              Author      Files  Comments  Merged
1234  Add user authentication            @alice      12     8         2d ago
1233  Fix memory leak in parser          @bob        3      2         3d ago

Notable PRs

When notable is specified:

gh pr list -R <repo> --state merged --limit 50 --json number,title,author,files,comments,body,mergedAt

Filter and rank by:

1. Comment count (most discussed)
2. Files touching 5+ directories (architectural)
3. Body length > 500 chars (well-documented)

Output the top 10 most educational PRs with brief explanations of why they're notable.

PR Deep Dive

When a PR number is specified:

gh pr view <number> -R <repo> --json title,body,author,files,comments,reviews,mergedAt

Extract and present:

• Title and author
• Problem: First paragraph of body (usually explains the why)
• Key files: List files changed, grouped by directory
• Discussion: Summarize review comments, focus on substantive feedback
• Outcome: What was decided, any follow-up items mentioned

If the description is minimal, also fetch the diff to understand changes:

gh pr diff <number> -R <repo>

Area Focus

When area:<path> is specified:

gh pr list -R <repo> --state merged --limit 50 --json number,title,author,files,mergedAt

Filter PRs where any file path contains <path>. Show:

• PRs that touched that area
• When they were merged
• What changed

This reveals the evolution of a specific part of the codebase.

Output Guidelines

• Use tables for lists of PRs
• Use headers to separate sections
• Include PR numbers as #1234 for easy reference
• For deep dives, quote notable review comments
• Keep summaries concise but informative