/pr-describe

Generate or update the PR description to reflect all changes from main. Works for initial PRs and follow-up commits.

Steps:

1. Check PR exists:

   • Run gh pr view --json number,body -q '.number'
   • If no PR exists, tell user to create one first

2. Get all changes from main:

   • Run git log main..HEAD --oneline to see all commits
   • Run git diff main...HEAD --stat for changed files summary
   • Run git diff main...HEAD for full diff (if not too large)

3. Generate PR description following best practices:

   ## Summary
   <!-- 2-3 sentences: what changed and WHY -->
   
   ## Changes
   <!-- Bullet list of key changes, grouped by concept -->
   -
   
   ## Test Plan
   <!-- How to verify this works (if applicable) -->
   
   ## Related Issues
   <!-- Use "Closes #123" to auto-link/close issues -->
   

   Guidelines:

   • Focus on the "what" and "why", not implementation details
   • Group related changes by concept/problem being solved
   • Include screenshots section if UI changes detected (leave placeholder)
   • Keep it concise but informative
   • Use Closes #N or Fixes #N to link issues

4. Show the description to user and ask for confirmation before updating

5. Update the PR:

   • Run gh pr edit --body "<description>"

6. Confirm the PR was updated with link to view it.