feat(settings): user timezone preference for scheduled tasks

Add a Timezone preference under Settings → General. Scheduled tasks now run
in the user's chosen IANA zone instead of whatever device created them.

- settings table gains a nullable `timezone` column (migration 0236); null
  means "use the browser-detected zone", so existing users are unchanged
- contract: validated IANA `timezone` on the settings get/update shapes
- useTimezone() resolves the saved zone or the browser fallback; the task
  modal captures it instead of recomputing the device zone
- General settings adds a searchable timezone combobox defaulting to the
  detected zone
- shared timezone util (getBrowserTimezone / getSupportedTimezones)

Author: waleedlatif1

apps/sim/app/api/users/me/settings/route.ts

@@ -24,6 +24,7 @@ const defaultSettings = {
   errorNotificationsEnabled: true,
   snapToGridSize: 0,
   showActionBar: true,
+  timezone: null,
   lastActiveWorkspaceId: null,
 }
 
@@ -52,6 +53,7 @@ export const GET = withRouteHandler(async () => {
         errorNotificationsEnabled: settings.errorNotificationsEnabled,
         snapToGridSize: settings.snapToGridSize,
         showActionBar: settings.showActionBar,
+        timezone: settings.timezone,
         lastActiveWorkspaceId: settings.lastActiveWorkspaceId,
       })
       .from(settings)
@@ -78,6 +80,7 @@ export const GET = withRouteHandler(async () => {
           errorNotificationsEnabled: userSettings.errorNotificationsEnabled ?? true,
           snapToGridSize: userSettings.snapToGridSize ?? 0,
           showActionBar: userSettings.showActionBar ?? true,
+          timezone: userSettings.timezone ?? null,
           lastActiveWorkspaceId: userSettings.lastActiveWorkspaceId ?? null,
         },
       },

apps/sim/app/workspace/[workspaceId]/scheduled-tasks/components/schedule-calendar/components/time-grid/time-grid.tsx

@@ -138,7 +138,7 @@ function DayEvents({
  * they stay aligned. The sticky header paints chrome on the day cells only —
  * its gutter spacer is transparent and border-free, so the hour labels scroll
  * clear to the top of the viewport. Today's column is `relative` and hosts the
- * {@link CurrentTimeIndicator}. Events flow in via `eventsByHour` — the single
+ * {@link CurrentTimeIndicator}. Events flow in via `eventsByDay` — the single
  * injection point the container fills.
  */
 export function TimeGrid({

apps/sim/app/workspace/[workspaceId]/scheduled-tasks/components/task-modal/task-modal.tsx

@@ -23,9 +23,9 @@ import {
   DEFAULT_RECURRENCE,
   type Recurrence,
 } from '@/app/workspace/[workspaceId]/scheduled-tasks/utils/recurrence'
+import { useTimezone } from '@/hooks/queries/general-settings'
 import type { ChatContext } from '@/stores/panel'
 
-const DEFAULT_TIMEZONE = Intl.DateTimeFormat().resolvedOptions().timeZone
 const DEFAULT_TIME = '09:00'
 const PAST_LAUNCH_MESSAGE = "You can't schedule a one-time task in the past"
 
@@ -131,6 +131,7 @@ function TaskModalContent({
   onRequestDelete,
 }: Omit<TaskModalProps, 'open'>) {
   const { workspaceId } = useParams<{ workspaceId: string }>()
+  const timezone = useTimezone()
   const editor = usePromptEditor({ workspaceId, initialValue: edit?.prompt })
   const setContexts = editor.setContexts
 
@@ -163,7 +164,7 @@ function TaskModalContent({
       contexts: editor.contexts.length > 0 ? editor.contexts : undefined,
       launchDate,
       launchTime,
-      timezone: DEFAULT_TIMEZONE,
+      timezone,
       recurrence,
     })
     close()

apps/sim/app/workspace/[workspaceId]/settings/components/general/general.tsx

@@ -8,6 +8,7 @@ import { useRouter } from 'next/navigation'
 import {
   Button,
   Chip,
+  ChipCombobox,
   ChipModal,
   ChipModalBody,
   ChipModalError,
@@ -26,6 +27,7 @@ import { ANONYMOUS_USER_ID } from '@/lib/auth/constants'
 import { getEnv, isTruthy } from '@/lib/core/config/env'
 import { isHosted } from '@/lib/core/config/feature-flags'
 import { handleKeyboardActivation } from '@/lib/core/utils/keyboard'
+import { getBrowserTimezone, getSupportedTimezones } from '@/lib/core/utils/timezone'
 import { getBaseUrl } from '@/lib/core/utils/urls'
 import { SettingsSection } from '@/app/workspace/[workspaceId]/settings/components/settings-section/settings-section'
 import { useProfilePictureUpload } from '@/app/workspace/[workspaceId]/settings/hooks/use-profile-picture-upload'
@@ -40,6 +42,12 @@ import { clearUserData } from '@/stores'
 
 const logger = createLogger('General')
 
+/** IANA zones for the timezone picker; labels drop underscores so search reads naturally. */
+const TIMEZONE_OPTIONS = getSupportedTimezones().map((tz) => ({
+  label: tz.replace(/_/g, ' '),
+  value: tz,
+}))
+
 /**
  * Extracts initials from a user's name.
  * @param name - The user's full name
@@ -197,6 +205,10 @@ export function General() {
     await updateSetting.mutateAsync({ key: 'theme', value: value as 'system' | 'light' | 'dark' })
   }
 
+  const handleTimezoneChange = async (value: string) => {
+    await updateSetting.mutateAsync({ key: 'timezone', value })
+  }
+
   const handleAutoConnectChange = async (checked: boolean) => {
     if (checked !== settings?.autoConnect && !updateSetting.isPending) {
       await updateSetting.mutateAsync({ key: 'autoConnect', value: checked })
@@ -406,6 +418,31 @@ export function General() {
                 />
               </div>
 
+              <div className='flex items-center justify-between gap-4'>
+                <div className='flex items-center gap-1.5'>
+                  <Label htmlFor='timezone-select'>Timezone</Label>
+                  <Tooltip.Root>
+                    <Tooltip.Trigger asChild>
+                      <Info className='size-[14px] cursor-default text-[var(--text-muted)]' />
+                    </Tooltip.Trigger>
+                    <Tooltip.Content side='bottom' align='start'>
+                      <p>The timezone scheduled tasks run in. Defaults to this device's zone.</p>
+                    </Tooltip.Content>
+                  </Tooltip.Root>
+                </div>
+                <ChipCombobox
+                  className='min-w-0 max-w-[260px]'
+                  align='start'
+                  dropdownWidth={260}
+                  searchable
+                  searchPlaceholder='Search timezones'
+                  value={settings?.timezone ?? getBrowserTimezone()}
+                  onChange={handleTimezoneChange}
+                  placeholder='Select timezone'
+                  options={TIMEZONE_OPTIONS}
+                />
+              </div>
+
               <div className='flex items-center justify-between'>
                 <div className='flex items-center gap-1.5'>
                   <Label htmlFor='auto-connect'>Auto-connect on drop</Label>

apps/sim/hooks/queries/general-settings.ts

@@ -9,6 +9,7 @@ import {
   updateUserSettingsContract,
 } from '@/lib/api/contracts'
 import { syncThemeToNextThemes } from '@/lib/core/utils/theme'
+import { getBrowserTimezone } from '@/lib/core/utils/timezone'
 
 const logger = createLogger('GeneralSettingsQuery')
 
@@ -34,6 +35,8 @@ export interface GeneralSettings {
   errorNotificationsEnabled: boolean
   snapToGridSize: number
   showActionBar: boolean
+  /** Saved IANA timezone, or `null` when unset (the app falls back to the browser zone). */
+  timezone: string | null
 }
 
 /**
@@ -52,6 +55,7 @@ export function mapGeneralSettingsResponse(data: UserSettingsApi): GeneralSettin
     errorNotificationsEnabled: data.errorNotificationsEnabled,
     snapToGridSize: data.snapToGridSize,
     showActionBar: data.showActionBar,
+    timezone: data.timezone ?? null,
   }
 }
 
@@ -130,6 +134,16 @@ export function useErrorNotificationsEnabled(): boolean {
   return data?.errorNotificationsEnabled ?? true
 }
 
+/**
+ * The user's effective scheduling timezone: their saved preference, or the
+ * browser-detected zone when unset. Use this wherever a task's timezone is
+ * captured so scheduling honors the account preference rather than the device.
+ */
+export function useTimezone(): string {
+  const { data } = useGeneralSettings()
+  return data?.timezone ?? getBrowserTimezone()
+}
+
 /**
  * Update general settings mutation
  */

apps/sim/lib/api/contracts/user.ts

@@ -64,6 +64,19 @@ export const userSettingsEmailPreferencesSchema = z.object({
 export const mothershipEnvironmentSchema = z.enum(['default', 'dev', 'staging', 'prod'])
 export type MothershipEnvironment = z.infer<typeof mothershipEnvironmentSchema>
 
+/** An IANA timezone identifier (e.g. `America/New_York`), validated against the runtime's zone database. */
+export const ianaTimezoneSchema = z.string().refine(
+  (tz) => {
+    try {
+      new Intl.DateTimeFormat('en-US', { timeZone: tz })
+      return true
+    } catch {
+      return false
+    }
+  },
+  { message: 'Must be a valid IANA timezone (e.g. America/New_York)' }
+)
+
 export const userSettingsSchema = z.object({
   theme: z.enum(['system', 'light', 'dark']).default('system'),
   autoConnect: z.boolean().default(true),
@@ -76,6 +89,8 @@ export const userSettingsSchema = z.object({
   errorNotificationsEnabled: z.boolean().default(true),
   snapToGridSize: z.number().min(0).max(50).default(0),
   showActionBar: z.boolean().default(true),
+  /** IANA timezone for scheduling; `null` means the client falls back to the browser-detected zone. */
+  timezone: z.string().nullable().default(null),
   lastActiveWorkspaceId: z.string().nullable().optional(),
 })
 
@@ -93,6 +108,8 @@ export const updateUserSettingsBodySchema = z.object({
   errorNotificationsEnabled: z.boolean().optional(),
   snapToGridSize: z.number().min(0).max(50).optional(),
   showActionBar: z.boolean().optional(),
+  /** IANA timezone; explicit `null` resets to the browser-detected zone. */
+  timezone: ianaTimezoneSchema.nullable().optional(),
   /** Mirrors `userSettingsSchema.lastActiveWorkspaceId` so explicit `null` is accepted to clear the active workspace. */
   lastActiveWorkspaceId: z.string().nullable().optional(),
 })

apps/sim/lib/core/utils/timezone.ts

@@ -0,0 +1,12 @@
+/** The IANA timezone the current runtime resolves to (e.g. `America/New_York`). */
+export function getBrowserTimezone(): string {
+  return Intl.DateTimeFormat().resolvedOptions().timeZone
+}
+
+/**
+ * Every IANA timezone identifier the runtime knows, for populating a picker.
+ * Empty on runtimes without `Intl.supportedValuesOf` so callers can fall back.
+ */
+export function getSupportedTimezones(): string[] {
+  return typeof Intl.supportedValuesOf === 'function' ? Intl.supportedValuesOf('timeZone') : []
+}

packages/db/migrations/0237_user_settings_timezone.sql

@@ -0,0 +1 @@
+ALTER TABLE "settings" ADD COLUMN "timezone" text;