Diffity Diff Skill

Arguments

• ref

  (optional): Git ref to diff (e.g.

  main..feature

  ,

  HEAD~3

  ) or a GitHub PR URL (e.g.

  https://github.com/owner/repo/pull/123

  ). Defaults to working tree changes.

Instructions

1. Check that

   diffity

   is available: run

   which diffity

   . If not found, install it with

   npm install -g diffity

   .
2. Run

   diffity <ref>

   (or just

   diffity

   if no ref) using the Bash tool with

   run_in_background: true

   :
   • The CLI handles everything: if an instance is already running for this repo it reuses it and opens the browser, otherwise it starts a new server and opens the browser.
   • Do NOT use

     &

     or

     --quiet

     — let the Bash tool handle backgrounding.
3. Wait 2 seconds, then run

   diffity list --json

   to get the port.
4. Tell the user diffity is running. Print the URL and keep it short — don't show session IDs, hashes, or other internals. Example:

   Diffity is running at http://localhost:5391

   When you're ready:

   • Leave comments on the diff in your browser, then run /diffity-resolve to fix them
   • Or run /diffity-review to get an AI code review