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viewport::grid_body makes one FoldMemo and passes it to every cell and total through GridLayout::evaluate_in / column_total, so a fold row's formula chain is evaluated once across the row (9, not 45). The bench gains a folded five-formula chain case; stored-only grids are unchanged. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze