fix(google-calendar): require timeZone for recurring timed events, clarify recurrence replace semantics

Author: waleedlatif1

apps/sim/tools/google_calendar/create.ts

@@ -7,6 +7,7 @@ import {
   type GoogleCalendarEventRequestBody,
 } from '@/tools/google_calendar/types'
 import {
+  assertRecurringTimeZone,
   buildEventDateTime,
   buildGoogleMeetConferenceData,
   normalizeAttendees,
@@ -128,6 +129,10 @@ export const createTool: ToolConfig<GoogleCalendarCreateParams, GoogleCalendarCr
       const recurrence = normalizeRecurrence(params.recurrence)
       const isRecurring = recurrence.length > 0
 
+      if (isRecurring) {
+        assertRecurringTimeZone([params.startDateTime, params.endDateTime], params.timeZone)
+      }
+
       const eventData: GoogleCalendarEventRequestBody = {
         summary: params.summary,
         start: buildEventDateTime(params.startDateTime, params.timeZone),

apps/sim/tools/google_calendar/update.ts

@@ -7,6 +7,7 @@ import {
   type GoogleCalendarUpdateResponse,
 } from '@/tools/google_calendar/types'
 import {
+  assertRecurringTimeZone,
   buildEventDateTime,
   buildGoogleMeetConferenceData,
   normalizeAttendees,
@@ -97,7 +98,7 @@ export const updateTool: ToolConfig<GoogleCalendarUpdateParams, GoogleCalendarUp
       required: false,
       visibility: 'user-or-llm',
       description:
-        'Recurrence rule(s) in RFC 5545 format (e.g., RRULE:FREQ=WEEKLY;BYDAY=MO,WE,FR). Separate multiple rules with newlines.',
+        "Recurrence rule(s) in RFC 5545 format (e.g., RRULE:FREQ=WEEKLY;BYDAY=MO,WE,FR). Separate multiple rules with newlines. When provided, replaces the event's recurrence; leaving it empty keeps the existing recurrence unchanged. Requires a timeZone for timed events.",
     },
     addGoogleMeet: {
       type: 'boolean',
@@ -138,6 +139,10 @@ export const updateTool: ToolConfig<GoogleCalendarUpdateParams, GoogleCalendarUp
       const recurrence = normalizeRecurrence(params.recurrence)
       const isRecurring = recurrence.length > 0
 
+      if (isRecurring) {
+        assertRecurringTimeZone([params.startDateTime, params.endDateTime], params.timeZone)
+      }
+
       if (params.summary !== undefined) {
         updateData.summary = params.summary
       }

apps/sim/tools/google_calendar/utils.ts

@@ -48,6 +48,26 @@ export function normalizeAttendees(
   return list.filter((email) => email.length > 0).map((email) => ({ email }))
 }
 
+/**
+ * Recurring events require a named `timeZone` on their timed start/end — the Calendar API
+ * rejects them otherwise, and an RFC3339 offset is not a substitute (an IANA zone cannot be
+ * derived from a fixed offset). Throws a clear error so we fail fast with guidance instead of
+ * silently guessing a zone (which would misalign the recurrence) or sending an invalid request.
+ * All-day recurring events (date-only values) do not need a timezone and are allowed.
+ */
+export function assertRecurringTimeZone(
+  dateTimes: Array<string | undefined>,
+  timeZone: string | undefined
+): void {
+  if (timeZone) return
+  const hasTimedValue = dateTimes.some((value) => value?.includes('T'))
+  if (hasTimedValue) {
+    throw new Error(
+      'Recurring events require a time zone. Provide the timeZone parameter (an IANA name, e.g. America/New_York).'
+    )
+  }
+}
+
 /** Normalize recurrence rules (single string, newline-separated string, or array) into an array. */
 export function normalizeRecurrence(recurrence: string | string[] | undefined): string[] {
   if (!recurrence) return []