refactor: use date-fns/tz instead of a custom tz impl

apps/desktop/src/components/main/sidebar/timeline/item.tsx

@@ -8,7 +8,7 @@ import {
   TooltipContent,
   TooltipTrigger,
 } from "@hypr/ui/components/ui/tooltip";
-import { cn, safeParseDate } from "@hypr/utils";
+import { cn, format, getYear, safeParseDate, TZDate } from "@hypr/utils";
 
 import { useListener } from "../../../../contexts/listener";
 import { useIsSessionEnhancing } from "../../../../hooks/useEnhancedNotes";
@@ -423,47 +423,23 @@ function formatDisplayTime(
   precision: TimelinePrecision,
   timezone?: string,
 ): string {
-  const date = safeParseDate(timestamp);
-  if (!date) {
+  const parsed = safeParseDate(timestamp);
+  if (!parsed) {
     return "";
   }
 
-  const timeOptions: Intl.DateTimeFormatOptions = {
-    hour: "numeric",
-    minute: "numeric",
-    timeZone: timezone,
-  };
-
-  const time = date.toLocaleTimeString([], timeOptions);
+  const date = timezone ? new TZDate(parsed, timezone) : parsed;
+  const time = format(date, "h:mm a");
 
   if (precision === "time") {
     return time;
   }
 
-  const now = new Date();
-  const yearInTz = timezone
-    ? parseInt(
-        new Intl.DateTimeFormat("en-US", {
-          year: "numeric",
-          timeZone: timezone,
-        }).format(date),
-      )
-    : date.getFullYear();
-  const currentYearInTz = timezone
-    ? parseInt(
-        new Intl.DateTimeFormat("en-US", {
-          year: "numeric",
-          timeZone: timezone,
-        }).format(now),
-      )
-    : now.getFullYear();
-  const sameYear = yearInTz === currentYearInTz;
-
-  const dateOptions: Intl.DateTimeFormatOptions = sameYear
-    ? { month: "short", day: "numeric", timeZone: timezone }
-    : { month: "short", day: "numeric", year: "numeric", timeZone: timezone };
-
-  const dateStr = date.toLocaleDateString([], dateOptions);
+  const now = timezone ? new TZDate(new Date(), timezone) : new Date();
+  const sameYear = getYear(date) === getYear(now);
+  const dateStr = sameYear
+    ? format(date, "MMM d")
+    : format(date, "MMM d, yyyy");
 
   return `${dateStr}, ${time}`;
 }

apps/desktop/src/utils/timeline.ts

@@ -1,55 +1,15 @@
-import { isPast, safeParseDate } from "@hypr/utils";
-
-interface DateParts {
-  year: number;
-  month: number;
-  day: number;
-}
-
-function getDatePartsInTimezone(date: Date, timezone?: string): DateParts {
-  const formatter = new Intl.DateTimeFormat("en-CA", {
-    timeZone: timezone,
-    year: "numeric",
-    month: "2-digit",
-    day: "2-digit",
-  });
-  const formatted = formatter.format(date);
-  const [year, month, day] = formatted.split("-").map(Number);
-  return { year, month, day };
-}
-
-function datePartsToUtcMidnight(parts: DateParts): number {
-  return Date.UTC(parts.year, parts.month - 1, parts.day);
-}
-
-function differenceInCalendarDaysInTimezone(
-  dateLeft: Date,
-  dateRight: Date,
-  timezone?: string,
-): number {
-  const leftParts = getDatePartsInTimezone(dateLeft, timezone);
-  const rightParts = getDatePartsInTimezone(dateRight, timezone);
-  const leftUtc = datePartsToUtcMidnight(leftParts);
-  const rightUtc = datePartsToUtcMidnight(rightParts);
-  return Math.round((leftUtc - rightUtc) / (1000 * 60 * 60 * 24));
-}
-
-function differenceInCalendarMonthsInTimezone(
-  dateLeft: Date,
-  dateRight: Date,
-  timezone?: string,
-): number {
-  const leftParts = getDatePartsInTimezone(dateLeft, timezone);
-  const rightParts = getDatePartsInTimezone(dateRight, timezone);
-  return (
-    (leftParts.year - rightParts.year) * 12 +
-    (leftParts.month - rightParts.month)
-  );
-}
-
-function getSortKeyForDateInTimezone(date: Date, timezone?: string): number {
-  const parts = getDatePartsInTimezone(date, timezone);
-  return datePartsToUtcMidnight(parts);
+import {
+  differenceInCalendarDays,
+  differenceInCalendarMonths,
+  isPast,
+  safeParseDate,
+  startOfDay,
+  startOfMonth,
+  TZDate,
+} from "@hypr/utils";
+
+function toTZ(date: Date, timezone?: string): Date {
+  return timezone ? new TZDate(date, timezone) : date;
 }
 
 // comes from QUERIES.timelineEvents
@@ -109,8 +69,10 @@ export function getBucketInfo(
   precision: TimelinePrecision;
 } {
   const now = new Date();
-  const daysDiff = differenceInCalendarDaysInTimezone(date, now, timezone);
-  const sortKey = getSortKeyForDateInTimezone(date, timezone);
+  const tzDate = toTZ(date, timezone);
+  const tzNow = toTZ(now, timezone);
+  const daysDiff = differenceInCalendarDays(tzDate, tzNow);
+  const sortKey = startOfDay(tzDate).getTime();
   const absDays = Math.abs(daysDiff);
 
   if (daysDiff === 0) {
@@ -136,7 +98,7 @@ export function getBucketInfo(
       const weekRangeEnd = new Date(
         now.getTime() - weekRangeEndDay * 24 * 60 * 60 * 1000,
       );
-      const weekSortKey = getSortKeyForDateInTimezone(weekRangeEnd, timezone);
+      const weekSortKey = startOfDay(toTZ(weekRangeEnd, timezone)).getTime();
 
       return {
         label: weeks === 1 ? "a week ago" : `${weeks} weeks ago`,
@@ -145,25 +107,17 @@ export function getBucketInfo(
       };
     }
 
-    let months = Math.abs(
-      differenceInCalendarMonthsInTimezone(date, now, timezone),
-    );
+    let months = Math.abs(differenceInCalendarMonths(tzDate, tzNow));
     if (months === 0) {
       months = 1;
     }
-    const targetParts = getDatePartsInTimezone(date, timezone);
-    const monthStartKey = datePartsToUtcMidnight({
-      year: targetParts.year,
-      month: targetParts.month,
-      day: 1,
-    });
+    const monthStartKey = startOfMonth(tzDate).getTime();
     const lastDayInMonthBucket = new Date(
       now.getTime() - 28 * 24 * 60 * 60 * 1000,
     );
-    const lastDayKey = getSortKeyForDateInTimezone(
-      lastDayInMonthBucket,
-      timezone,
-    );
+    const lastDayKey = startOfDay(
+      toTZ(lastDayInMonthBucket, timezone),
+    ).getTime();
     const monthSortKey = Math.min(monthStartKey, lastDayKey);
     return {
       label: months === 1 ? "a month ago" : `${months} months ago`,
@@ -182,7 +136,7 @@ export function getBucketInfo(
     const weekRangeStart = new Date(
       now.getTime() + weekRangeStartDay * 24 * 60 * 60 * 1000,
     );
-    const weekSortKey = getSortKeyForDateInTimezone(weekRangeStart, timezone);
+    const weekSortKey = startOfDay(toTZ(weekRangeStart, timezone)).getTime();
 
     return {
       label: weeks === 1 ? "next week" : `in ${weeks} weeks`,
@@ -191,23 +145,17 @@ export function getBucketInfo(
     };
   }
 
-  let months = differenceInCalendarMonthsInTimezone(date, now, timezone);
+  let months = differenceInCalendarMonths(tzDate, tzNow);
   if (months === 0) {
     months = 1;
   }
-  const targetParts = getDatePartsInTimezone(date, timezone);
-  const monthStartKey = datePartsToUtcMidnight({
-    year: targetParts.year,
-    month: targetParts.month,
-    day: 1,
-  });
+  const monthStartKey = startOfMonth(tzDate).getTime();
   const firstDayInMonthBucket = new Date(
     now.getTime() + 28 * 24 * 60 * 60 * 1000,
   );
-  const firstDayKey = getSortKeyForDateInTimezone(
-    firstDayInMonthBucket,
-    timezone,
-  );
+  const firstDayKey = startOfDay(
+    toTZ(firstDayInMonthBucket, timezone),
+  ).getTime();
   const monthSortKey = Math.max(monthStartKey, firstDayKey);
   return {
     label: months === 1 ? "next month" : `in ${months} months`,

packages/utils/src/date.ts

@@ -9,6 +9,7 @@ import { format as dateFnsFormat, isValid } from "date-fns";
 
 // Re-export ALL date-fns functions so users can import any date-fns function from @hypr/utils
 export * from "date-fns";
+export { TZDate } from "@date-fns/tz";
 
 export function safeParseDate(value: unknown): Date | null {
   if (value === null || value === undefined) {