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).
Davide Scaini
104328bc50