Lightweight Charts is timezone-agnostic: it reads epoch seconds as UTC and
labels them as UTC, so the axis disagreed with the wall clock by the viewer's
offset. tickMarkFormatter now formats axis ticks through the browser's own zone,
and localization.timeFormatter does the same for the crosshair readout, which
would otherwise contradict the axis.
Not done by shifting the bar timestamps, which is the other common recipe for
this. Every time in this codebase is epoch UTC by convention, and the chart's
times feed trendline anchors, indexAt, hit testing and the values posted back
for manual lines. An offset applied to the data would put every one of them out
by that offset — the same class of bug that once priced a trendline 147 points
from where it was drawn.
Tick placement is still computed on UTC days, so the day-change divider sits at
00:00 UTC rather than local midnight, carrying the local date. Verified under
America/Chicago: a bar at 13:03 UTC labels as 08:03 and the axis reads 05:30
through 08:00, with no console errors.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Chris Amow
d1056ed486