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views/formulas were empty-means-closed, so an open panel over a document with no formulas built the same RenderModel as a closed one. Option<Vec<_>> carries both facts in one field; the page hides on null. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze