BugBot duplicate-fix preflight

Steps:

1. Search open PR titles for the affected file or symbol — avoids competing fixes.
2. Search all issues for the symbol — finds prior diagnosis and superseding work.
3. Rebase onto current main and reproduce again — stale CI or snapshots do not prove the defect remains.
4. Extend or comment on an existing touching PR instead of opening a duplicate.
5. Rerun verification before requesting review. Gotchas:

• Bundling subjective wording/default changes with correctness fixes looks efficient but obscures the regression; keep UX opinions separate. Verify:
• [ ] gh pr list --state open --search "in:title <file-or-symbol>" checked.
• [ ] gh issue list --state all --search "<symbol>" checked.
• [ ] Failure reproduces on rebased main.