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fix(map): anchor timeline offsets to the Now slot, not wall-clock

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When wall-clock is past :30, the hour *after* Now rounded to "0h" and
the Now slot kept its "Now" tag — two adjacent buttons both reading
as the current hour. Anchor the offset math to the Now slot itself so
the label sequence reads "-1h / Now / +1h / +2h" regardless of where
inside the hour the user loaded the page.
This commit is contained in:
Graham McIntire 2026-04-19 12:32:41 -05:00
parent fd48263992
commit 9db9e6a893
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GPG key ID: F4ABF488E6029E59
1 changed files with 8 additions and 3 deletions
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11
assets/js/propagation_map_hook.ts
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@ -1326,8 +1326,7 @@ export const PropagationMap: Record<string, unknown> & {
const dt = new Date(t.time)
const isSelected = t.time === this.selectedTime
const isPast = dt.getTime() < now.getTime() - 1800000 // 30min grace
const offsetH = Math.round((dt.getTime() - now.getTime()) / 3600000)
return { ...t, dt, isSelected, isPast, offsetH, idx, label: "" }
return { ...t, dt, isSelected, isPast, offsetH: 0, idx, label: "" }
})
// "Now" = the latest forecast hour at or before wall-clock. Picking
@ -1343,11 +1342,17 @@ export const PropagationMap: Record<string, unknown> & {
? items.indexOf(pastOrNow.reduce((latest, t) => t.dt.getTime() > latest.dt.getTime() ? t : latest))
: -1
// Label offsets relative to the "Now" slot, not wall-clock. If we
// round from wall-clock, the hour after "Now" rounds to "0h" when
// the clock is past the half-hour, which reads as a second "now".
const anchorMs = nowIdx >= 0 ? items[nowIdx].dt.getTime() : nowMs
items.forEach((t, i) => {
const diff = Math.round((t.dt.getTime() - anchorMs) / 3600000)
t.offsetH = diff
if (i === nowIdx) {
t.label = "Now"
} else {
const diff = t.offsetH
t.label = diff > 0 ? `+${diff}h` : `${diff}h`
}
})