Fix availability that goes from one day to another

app/features/availability/core/Availability.ts

@@ -220,6 +220,32 @@ export function clip(
 	});
 }
 
+/** The ranges cut up into the day tracks they render on, what runs past a track's end continuing on the next day's. */
+export function splitByDayTracks(
+	ranges: Array<TimeRange>,
+	timezone: string,
+): Array<TimeRange> {
+	return ranges.flatMap((range) => {
+		const tracks: Array<TimeRange> = [];
+
+		let startsAt = range.startsAt;
+		while (startsAt < range.endsAt) {
+			const trackEndsAt = dayMinutesToTimestamp({
+				date: dateInTimezone(startsAt, timezone),
+				minutes: AVAILABILITY.TRACK_LATER_END_MINUTES,
+				timezone,
+			});
+			const endsAt = Math.min(range.endsAt, trackEndsAt);
+			if (endsAt <= startsAt) break;
+
+			tracks.push({ startsAt, endsAt });
+			startsAt = endsAt;
+		}
+
+		return tracks;
+	});
+}
+
 /**
  * How one person's schedule relates to an event's window. A busy block overlapping it
  * wins over anything reported (committed elsewhere, schedule known or not). Otherwise the

app/features/availability/core/MySchedule.server.ts

@@ -84,10 +84,15 @@ function editorWeek({
 		Availability.isSameWeek(week.weekStartsAt, range.startsAt),
 	);
 
+	const slots = Availability.splitByDayTracks(
+		matchingWeek?.slots ?? [],
+		timezone,
+	);
+
 	const days = ScheduleWeek.days(range, timezone).map(({ date }) => ({
 		date,
 		ranges: Availability.mergedDayRanges(
-			(matchingWeek?.slots ?? [])
+			slots
 				.filter(
 					(slot) =>
 						Availability.dateInTimezone(slot.startsAt, timezone) === date,

app/features/availability/core/ScheduleWeek.test.ts

@@ -0,0 +1,50 @@
+import { addWeeks } from "date-fns";
+import { describe, expect, test } from "vitest";
+import * as Availability from "./Availability";
+import * as ScheduleWeek from "./ScheduleWeek";
+
+const DAY_SECONDS = 24 * 60 * 60;
+const TIMEZONE = "UTC";
+const FRIDAY = 4;
+const SATURDAY = 5;
+
+describe("ScheduleWeek.memberRow", () => {
+	test("shows a member free on Saturday when their Friday night range runs into their Saturday morning range", () => {
+		const weekStartsAt = Availability.weekStartsAt(
+			addWeeks(new Date(), 1),
+			TIMEZONE,
+		);
+		const range = {
+			startsAt: weekStartsAt,
+			endsAt: weekStartsAt + 7 * DAY_SECONDS,
+		};
+		const days = ScheduleWeek.days(range, TIMEZONE);
+		const fridayAt = (minutes: number) =>
+			Availability.dayMinutesToTimestamp({
+				date: days[FRIDAY].date,
+				minutes,
+				timezone: TIMEZONE,
+			});
+
+		// what SAVE_WEEK stores for Fri 20:00-06:00 + Sat 06:00-10:00
+		const slots = Availability.normalize([
+			{ startsAt: fridayAt(20 * 60), endsAt: fridayAt(30 * 60) },
+			{ startsAt: fridayAt(30 * 60), endsAt: fridayAt(34 * 60) },
+		]);
+
+		const row = ScheduleWeek.memberRow({
+			userId: 1,
+			days,
+			timezone: TIMEZONE,
+			reportedWeeks: [
+				{ userId: 1, weekStartsAt, timezone: TIMEZONE, slots, dayNotes: [] },
+			],
+			range,
+			busy: [],
+		});
+
+		expect(row.days[SATURDAY].ranges).toEqual([
+			{ startsAt: fridayAt(30 * 60), endsAt: fridayAt(34 * 60) },
+		]);
+	});
+});

app/features/availability/core/ScheduleWeek.ts

@@ -48,8 +48,9 @@ export function weekNumber(range: TimeRange, timezone: string) {
 
 /**
  * One member's week bucketed into the viewer's days: effective free time (commitments cut out
- * first), the commitments and their notes. Slots land on the viewer-local day they start on,
- * wherever the author's week put them, adjacent weeks' spillover included.
+ * first), the commitments and their notes. Slots land on the viewer-local day track they start
+ * on, wherever the author's week put them, adjacent weeks' spillover included, and what runs past
+ * the end of that track continues on the next day.
  */
 export function memberRow({
 	userId,
@@ -89,9 +90,12 @@ export function memberRow({
 		};
 	}
 
-	const slots = Availability.subtract(
-		memberWeeks.flatMap((week) => week.slots),
-		busy,
+	const slots = Availability.splitByDayTracks(
+		Availability.subtract(
+			memberWeeks.flatMap((week) => week.slots),
+			busy,
+		),
+		timezone,
 	);
 
 	return {

changelog/2026-09-02-schedule-overnight-days.md

@@ -0,0 +1,5 @@
+---
+navItem: calendar
+type: bug
+---
+Fixed availability that runs into the next morning making that next day look empty on your schedule and on your team's