pr-updatelisted

# Update an Existing PR Update the description of PR #$ARGUMENTS. ## Steps ### 1. Fetch current PR state Run: ```text gh pr view $ARGUMENTS --json body,title,headRefName,baseRefName ``` ### 2. Find the watermark Look in the PR body for a comment in this exact format: ```text <!-- pr-update-watermark: <commit-sha> --> ``` If found, note the SHA — this is where the last update stopped. Call it `$WATERMARK_SHA`. If not found, treat the entire commit history on the branch as new. ### 3. Get new commits Run: ```text git log <baseRefName>..<headRefName> --oneline ``` If a watermark was found, filter to only commits **after** `$WATERMARK_SHA`: ```text git log ${WATERMARK_SHA}..HEAD --oneline ``` If there are no new commits since the watermark, tell me and stop — the description is already up to date. ### 4. Analyse the new commits For each new commit, run: ```text git show <sha> --stat ``` Understand what changed and why. Group related commits into coherent change categories. ### 5. Produce the updated PR body Take the existing PR body and update it: - **Do not rewrite from scratch.** Preserve existing content unless it is now inaccurate. - The body structure follows `~/.claude/library/templates/pr-description.md` (the same template `pr-create` fills) — keep updates within that structure rather than adding new top-level sections. - Update the `## Changes` section to incorporate the new commits. If collapsible `<details>` blocks already exist, add new entries o