fix: timezone parsing issues for calendars

packages/app-store/ics-feedcalendar/lib/CalendarService.ts

@@ -159,11 +159,17 @@ export default class ICSFeedCalendarService implements Calendar {
         // if (vevent?.getFirstPropertyValue("transp") === "TRANSPARENT") return;
 
         const event = new ICAL.Event(vevent);
+        // Fix timezone extraction - get TZID from DTSTART property parameters
+        const dtstartProperty = vevent.getFirstProperty("dtstart");
+        const tzidFromDtstart = dtstartProperty?.getParameter("tzid");
+
         const dtstart: { [key: string]: string } | undefined = vevent?.getFirstPropertyValue("dtstart");
         const timezone = dtstart ? dtstart["timezone"] : undefined;
         // We check if the dtstart timezone is in UTC which is actually represented by Z instead, but not recognized as that in ICAL.js as UTC
         const isUTC = timezone === "Z";
-        const tzid: string | undefined = vevent?.getFirstPropertyValue("tzid") || isUTC ? "UTC" : timezone;
+
+        // Fix precedence: prioritize TZID from DTSTART property, then check for UTC, then fallback
+        const tzid: string | undefined = tzidFromDtstart || (isUTC ? "UTC" : timezone);
         // In case of icalendar, when only tzid is available without vtimezone, we need to add vtimezone explicitly to take care of timezone diff
         if (!vcalendar.getFirstSubcomponent("vtimezone")) {
           const timezoneToUse = tzid || userTimeZone;

packages/lib/CalendarService.ts

@@ -393,11 +393,17 @@ export default abstract class BaseCalendarService implements Calendar {
         if (vevent?.getFirstPropertyValue("transp") === "TRANSPARENT") return;
 
         const event = new ICAL.Event(vevent);
+        // Fix timezone extraction - get TZID from DTSTART property parameters
+        const dtstartProperty = vevent.getFirstProperty("dtstart");
+        const tzidFromDtstart = dtstartProperty?.getParameter("tzid");
+
         const dtstart: { [key: string]: string } | undefined = vevent?.getFirstPropertyValue("dtstart");
         const timezone = dtstart ? dtstart["timezone"] : undefined;
         // We check if the dtstart timezone is in UTC which is actually represented by Z instead, but not recognized as that in ICAL.js as UTC
         const isUTC = timezone === "Z";
-        const tzid: string | undefined = vevent?.getFirstPropertyValue("tzid") || isUTC ? "UTC" : timezone;
+
+        // Fix precedence: prioritize TZID from DTSTART property, then check for UTC, then fallback
+        const tzid: string | undefined = tzidFromDtstart || (isUTC ? "UTC" : timezone);
         // In case of icalendar, when only tzid is available without vtimezone, we need to add vtimezone explicitly to take care of timezone diff
         if (!vcalendar.getFirstSubcomponent("vtimezone")) {
           const timezoneToUse = tzid || userTimeZone;