- Lock #positioning-canvas min-height to current offsetHeight before each
HTMX swap, release it in htmx:afterSwap — prevents flash-to-zero during
Chart.js initialization in the new content
- Add CSS min-height:200px fallback on all canvas containers so they never
fully collapse even before JS runs
- Extract _swapCanvas() helper to deduplicate setRange/setType logic
Root cause of visual collapse: cot_positioning_combined table missing
(needs sqlmesh plan prod + export_serving to materialize).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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