prepare-branch-context

name	prepare-branch-context
description	Analyze the current branch's diff from main and related PR to build context for followup requests. Triggers on "prepare context", "branch context", "catch me up", "what's on this branch".
user-invocable	true

Prepare Branch Context

Build a comprehensive understanding of the current branch so you can handle followup requests with full context.

Steps

1. Identify the current branch and base branch:

   git branch --show-current
   git merge-base HEAD main
   

2. Gather the diff from main:

   git diff main...HEAD --stat
   git diff main...HEAD
   

   Read through the full diff carefully. Understand what files were changed, added, or removed, and what the changes do.

3. Review the commit history on this branch:

   git log main..HEAD --oneline
   

   Read commit messages to understand the progression of changes.

4. Check for a related PR:

   gh pr list --head "$(git branch --show-current)" --json number,title,body,url,state,comments --jq '.[0]'
   

   If a PR exists, read its title, description, and comments for additional context (acceptance criteria, discussion, review feedback).

5. Summarize your understanding to the user:

   • What this branch does (high-level purpose)
   • Key files and areas of the codebase affected
   • Notable decisions or patterns visible in the changes
   • Any open review comments or discussion from the PR
   • Current state (clean, uncommitted changes, etc.)

6. Signal readiness: Tell the user you're ready for followup questions or tasks related to this branch.

Rules

• Do NOT make any changes to files. This skill is read-only.
• Read the actual diff content, not just the stat summary. You need to understand the code changes.
• If there's no PR, that's fine — just skip that step and note it.
• If the diff is very large, focus on understanding the overall structure first, then read key files in detail.
• Keep the summary concise but thorough enough that you could confidently make changes to this branch.
• If the branch is main or has no divergence from main, tell the user there's nothing to analyze.