Applied via `dotnet format analyzers --diagnostics IDE0028 CA1825 CA1834 CA1845 CA1847 CA1860 CA1866 CA1853 CA1830 CA1846 CA1806 CA1869 CA2249 --severity info`. 19 files touched, all mechanical syntactic rewrites: - CA1847: string.Contains("x") -> string.Contains('x') - CA2249: s.IndexOf(c) == -1 -> !s.Contains(c) - CA1830: sb.Append(sb.ToString()) -> sb.Append(sb) - CA1834: StringBuilder.Append("x") -> Append('x') - CA1825, CA1860, CA1866, CA1853, IDE0028, CA1845: corresponding fixers Three rules in the batch had no batch fixer available (CA1846 ×4, CA1806 ×1, CA1869 ×1) and stay open for separate manual handling. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>