- Snap clamps after rounding so it can't overshoot max on narrow viewports
- atEnd computed inline each render from live measureMax()
- forceUpdate on resize guarantees re-render even when left doesn't change
- Track gets explicit width (TOTAL_W) so gap areas are hit-testable
- Resize handler always calls setLeft (clamp or no-op) to keep state consistent
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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