_evaluate_simple_expression used 'if "|" in expr' / expr.split("|", 1) to detect a filter pipe, so a literal '|' inside a quoted operand (e.g. inputs.x == 'a|b') was mistaken for a filter separator and raised a spurious ValueError ('unknown filter') instead of comparing the string. Use the existing quote/bracket-aware _find_top_level helper (added for the operator-splitting fix) so only a top-level pipe is treated as a filter separator.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>