Three bugs in the time↔distance x-axis toggle:
1. GPS speed glitches (e.g. a 1-second spike at 222 km/h) were accumulated
into dist_km, pushing all subsequent points ~60 m too far right on the
distance axis and compressing the rest of the chart. Cap speed at 150 km/h
during dist_km integration; values above that are treated as 0 movement.
2. Observable Plot auto-infers the y domain from plottable points only.
When x-mode changes, which points are "plottable" changes too, so the
y axis range silently shifted between time and distance views. Fix by
computing lineDomainMin/Max once from the full dataset and passing an
explicit domain to Plot.
3. monotone-x curve requires strictly increasing x. In distance mode,
stopped segments produce consecutive points with identical dist_km,
causing NaN Bézier control points and visual artifacts. Use linear
curve for distance mode (data is dense enough that it looks smooth).
container div, causing the layout to collapse to zero height for a moment.
The browser then scrolls to keep the viewport anchored, but since the page
got shorter it jumps to the top. When the new SVG is appended, the page is
taller again but the scroll position was already reset.
Fix: give the chart container a min-height matching the chart height (220px)
so it never collapses.
Davide Scaini