Update PR

Overview

Rewrite pull request metadata as if drafting it from scratch for the current diff. Treat the title and body as a current reviewer-facing summary of the final net-new feature or bug fix in the PR, not as commentary about prior versions of the PR or the path taken to get there.

Workflow

1. Read the current PR title/body and the current branch diff before drafting.
2. Identify the PR's current net-new scope, APIs, behavior changes, and reviewer-relevant context.
3. Rewrite the body from scratch so it describes the shipped feature/fix as it exists now.
4. Review the title at the same time and update it whenever the body is updated.
5. Apply the update with gh pr edit.

Rules