An existing PR title and body are provided in <existing_pr>, along with the full commit log in <commit_log>, changed files in <changed_files>, and diff in <diff> for the current branch. Update the PR title and body to reflect new commits. PRESERVATION RULES. Treat <existing_pr> as authoritative for all content it covers. Copy it verbatim — same wording, punctuation, capitalization, bullet order, section order, and section headers. Stylistic rewording is forbidden; factual correction from new commits is required. Title — rewrite ONLY if new commits change the Conventional Commits type or scope, OR if the title's claim is now inaccurate (e.g. the feature was renamed, narrowed, or reverted in new commits). Otherwise leave byte-identical. Existing bullet — rewrite ONLY if a new commit invalidates its claim (e.g. a later commit changes the described behavior). Remove ONLY if the change was fully reverted. Otherwise leave byte-identical — do NOT adjust phrasing, tense, punctuation (periods, dashes, em-dashes, commas), or capitalization. Section headers and section order — never change. Adding new content — append new bullets from new commits to the end of the matching existing section. Do not interleave with or reorder existing bullets. Add a new section only if new commits introduce a Conventional Commits type not already present. Intra-branch churn — if a new commit is a fix/refactor of code introduced earlier in this same branch, prefer updating the existing bullet in place (if its claim is now wrong) over adding a new bullet. Do not list the churn itself. If uncertain whether a change is warranted, prefer no change. The title MUST use Conventional Commits format (feat:, fix:, refactor:, build:, chore:, docs:, style:, test:, perf:, ci:) on a single line. Use ! (e.g. feat!:) when this PR would require a semver MAJOR version bump — i.e., it removes or incompatibly changes behavior that users of the current release rely on. Examples: removed command or flag, renamed required argument, changed output format that consumers parse. When in doubt, omit !. If the changed interface was introduced after the last tag (never shipped to consumers), it is not breaking — omit !. Follow with a blank line, then the PR body: group changes by conventional commit type using markdown headers (e.g. ### Features, ### Bug Fixes, ### Refactors, ### Docs) and list each change as a concise bullet under the relevant section. Only include sections that have changes. Phrase each bullet as a practical outcome from the reader's perspective — describe what users or developers can now do, what no longer happens, or what improved — rather than listing implementation steps or internal file changes. After the change sections, add a ### Test Plan section with a short bullet list of manual steps a reviewer can follow to verify the changes work. Output ONLY the title and body. Do not wrap in code blocks or backticks.