Merge pull request #660 from rajnandan1/fix-timezone-sw

refactor: update timestamp handling to respect selected timezone

src/lib/components/MinuteGrid.svelte

@@ -5,6 +5,8 @@
   import TrendingUp from "@lucide/svelte/icons/trending-up";
   import { t } from "$lib/stores/i18n";
   import { formatDate } from "$lib/stores/datetime";
+  import { selectedTimezone } from "$lib/stores/timezone";
+  import { toZonedTime } from "date-fns-tz";
   import * as Tooltip from "$lib/components/ui/tooltip/index.js";
 
   interface MinuteData {
@@ -74,7 +76,7 @@
     const minutesByHour: Map<number, MinuteData[]> = new Map();
 
     for (const minute of minutes) {
-      const date = new Date(minute.timestamp * 1000);
+      const date = toZonedTime(minute.timestamp * 1000, $selectedTimezone);
       const hour = date.getHours();
 
       if (!minutesByHour.has(hour)) {

src/lib/stores/timezone.ts

@@ -37,7 +37,7 @@ function createTimezoneStore() {
       // Check localStorage for saved preference (only in browser)
       if (typeof window !== "undefined") {
         const savedTimezone = localStorage.getItem(TIMEZONE_STORAGE_KEY);
-        if (savedTimezone && allTimezones.includes(savedTimezone)) {
+        if (savedTimezone && (savedTimezone === "UTC" || allTimezones.includes(savedTimezone))) {
           preferredTimezone = savedTimezone;
         } else {
           // Save the default timezone to localStorage
@@ -47,7 +47,7 @@ function createTimezoneStore() {
 
       set({
         selectedTimezone: preferredTimezone,
-        availableTimezones: allTimezones,
+        availableTimezones: ["UTC", ...allTimezones],
       });
     },
 
@@ -56,7 +56,7 @@ function createTimezoneStore() {
      */
     setTimezone(timezone: string): void {
       update((state) => {
-        if (state.availableTimezones.includes(timezone)) {
+        if (timezone === "UTC" || state.availableTimezones.includes(timezone)) {
           // Save to localStorage
           if (typeof window !== "undefined") {
             localStorage.setItem(TIMEZONE_STORAGE_KEY, timezone);