From 061c1dff4eab6923ce741d203f0224ebdb8706c1 Mon Sep 17 00:00:00 2001
From: Vikhyath Mondreti <vikhyathvikku@gmail.com>
Date: Wed, 15 Oct 2025 11:37:42 -0700
Subject: [PATCH] fix(schedules): offload next run calculation to croner
 (#1640)

* fix(schedules): offload next run calculation to croner

* fix localstorage dependent tests

* address greptile comment
---
 apps/sim/app/api/schedules/route.ts           |   3 +-
 .../components/schedule/schedule-config.tsx   | 215 ++++++-----
 .../workflow-block/workflow-block.tsx         | 130 +++----
 apps/sim/background/schedule-execution.ts     |   8 +-
 apps/sim/lib/schedules/utils.test.ts          | 360 +++++++++++++-----
 apps/sim/lib/schedules/utils.ts               | 339 +++++------------
 apps/sim/stores/panel/console/store.test.ts   |   5 +
 apps/sim/vitest.setup.ts                      |  13 +
 bun.lock                                      |   5 +-
 package.json                                  |   1 +
 10 files changed, 569 insertions(+), 510 deletions(-)

diff --git a/apps/sim/app/api/schedules/route.ts b/apps/sim/app/api/schedules/route.ts
index ecbd7756d..0c9a5489d 100644
--- a/apps/sim/app/api/schedules/route.ts
+++ b/apps/sim/app/api/schedules/route.ts
@@ -309,7 +309,8 @@ export async function POST(req: NextRequest) {
 
       // Additional validation for custom cron expressions
       if (defaultScheduleType === 'custom' && cronExpression) {
-        const validation = validateCronExpression(cronExpression)
+        // Validate with timezone for accurate validation
+        const validation = validateCronExpression(cronExpression, timezone)
         if (!validation.isValid) {
           logger.error(`[${requestId}] Invalid cron expression: ${validation.error}`)
           return NextResponse.json(
diff --git a/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/workflow-block/components/sub-block/components/schedule/schedule-config.tsx b/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/workflow-block/components/sub-block/components/schedule/schedule-config.tsx
index 4b7ff9c99..372e11a3c 100644
--- a/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/workflow-block/components/sub-block/components/schedule/schedule-config.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/workflow-block/components/sub-block/components/schedule/schedule-config.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useState } from 'react'
+import { useCallback, useEffect, useState } from 'react'
 import { Calendar, ExternalLink } from 'lucide-react'
 import { useParams } from 'next/navigation'
 import { Button } from '@/components/ui/button'
@@ -33,17 +33,23 @@ export function ScheduleConfig({
   disabled = false,
 }: ScheduleConfigProps) {
   const [error, setError] = useState<string | null>(null)
-  const [scheduleId, setScheduleId] = useState<string | null>(null)
-  const [nextRunAt, setNextRunAt] = useState<string | null>(null)
-  const [lastRanAt, setLastRanAt] = useState<string | null>(null)
-  const [cronExpression, setCronExpression] = useState<string | null>(null)
-  const [timezone, setTimezone] = useState<string>('UTC')
+  const [scheduleData, setScheduleData] = useState<{
+    id: string | null
+    nextRunAt: string | null
+    lastRanAt: string | null
+    cronExpression: string | null
+    timezone: string
+  }>({
+    id: null,
+    nextRunAt: null,
+    lastRanAt: null,
+    cronExpression: null,
+    timezone: 'UTC',
+  })
   const [isLoading, setIsLoading] = useState(false)
   const [isSaving, setIsSaving] = useState(false)
   const [isDeleting, setIsDeleting] = useState(false)
   const [isModalOpen, setIsModalOpen] = useState(false)
-  // Track when we need to force a refresh of schedule data
-  const [refreshCounter, setRefreshCounter] = useState(0)
 
   const params = useParams()
   const workflowId = params.workflowId as string
@@ -61,79 +67,88 @@ export function ScheduleConfig({
   const blockWithValues = getBlockWithValues(blockId)
   const isScheduleTriggerBlock = blockWithValues?.type === 'schedule'
 
-  // Function to check if schedule exists in the database
-  const checkSchedule = async () => {
+  // Fetch schedule data from API
+  const fetchSchedule = useCallback(async () => {
+    if (!workflowId) return
+
     setIsLoading(true)
     try {
-      // Check if there's a schedule for this workflow, passing the mode parameter
-      // For schedule trigger blocks, include blockId to get the specific schedule
-      const url = new URL('/api/schedules', window.location.origin)
-      url.searchParams.set('workflowId', workflowId)
-      url.searchParams.set('mode', 'schedule')
-
+      const params = new URLSearchParams({
+        workflowId,
+        mode: 'schedule',
+      })
       if (isScheduleTriggerBlock) {
-        url.searchParams.set('blockId', blockId)
+        params.set('blockId', blockId)
       }
 
-      const response = await fetch(url.toString(), {
-        // Add cache: 'no-store' to prevent caching of this request
+      const response = await fetch(`/api/schedules?${params}`, {
         cache: 'no-store',
-        headers: {
-          'Cache-Control': 'no-cache',
-        },
+        headers: { 'Cache-Control': 'no-cache' },
       })
 
       if (response.ok) {
         const data = await response.json()
-        logger.debug('Schedule check response:', data)
-
         if (data.schedule) {
-          setScheduleId(data.schedule.id)
-          setNextRunAt(data.schedule.nextRunAt)
-          setLastRanAt(data.schedule.lastRanAt)
-          setCronExpression(data.schedule.cronExpression)
-          setTimezone(data.schedule.timezone || 'UTC')
-
-          // Note: We no longer set global schedule status from individual components
-          // The global schedule status should be managed by a higher-level component
+          setScheduleData({
+            id: data.schedule.id,
+            nextRunAt: data.schedule.nextRunAt,
+            lastRanAt: data.schedule.lastRanAt,
+            cronExpression: data.schedule.cronExpression,
+            timezone: data.schedule.timezone || 'UTC',
+          })
         } else {
-          setScheduleId(null)
-          setNextRunAt(null)
-          setLastRanAt(null)
-          setCronExpression(null)
-
-          // Note: We no longer set global schedule status from individual components
+          setScheduleData({
+            id: null,
+            nextRunAt: null,
+            lastRanAt: null,
+            cronExpression: null,
+            timezone: 'UTC',
+          })
         }
       }
     } catch (error) {
-      logger.error('Error checking schedule:', { error })
-      setError('Failed to check schedule status')
+      logger.error('Error fetching schedule:', error)
     } finally {
       setIsLoading(false)
     }
-  }
+  }, [workflowId, blockId, isScheduleTriggerBlock])
 
-  // Check for schedule on mount and when relevant dependencies change
+  // Fetch schedule data on mount and when dependencies change
   useEffect(() => {
-    // Check for schedules when workflowId changes, modal opens, or on initial mount
-    if (workflowId) {
-      checkSchedule()
+    fetchSchedule()
+  }, [fetchSchedule])
+
+  // Separate effect for event listener to avoid removing/re-adding on every dependency change
+  useEffect(() => {
+    const handleScheduleUpdate = (event: CustomEvent) => {
+      if (event.detail?.workflowId === workflowId && event.detail?.blockId === blockId) {
+        logger.debug('Schedule update event received in schedule-config, refetching')
+        fetchSchedule()
+      }
     }
 
-    // Cleanup function to reset loading state
+    window.addEventListener('schedule-updated', handleScheduleUpdate as EventListener)
+
     return () => {
-      setIsLoading(false)
+      window.removeEventListener('schedule-updated', handleScheduleUpdate as EventListener)
     }
-  }, [workflowId, isModalOpen, refreshCounter])
+  }, [workflowId, blockId, fetchSchedule])
+
+  // Refetch when modal opens to get latest data
+  useEffect(() => {
+    if (isModalOpen) {
+      fetchSchedule()
+    }
+  }, [isModalOpen, fetchSchedule])
 
   // Format the schedule information for display
   const getScheduleInfo = () => {
-    if (!scheduleId || !nextRunAt) return null
+    if (!scheduleData.id || !scheduleData.nextRunAt) return null
 
     let scheduleTiming = 'Unknown schedule'
 
-    if (cronExpression) {
-      scheduleTiming = parseCronToHumanReadable(cronExpression)
+    if (scheduleData.cronExpression) {
+      scheduleTiming = parseCronToHumanReadable(scheduleData.cronExpression, scheduleData.timezone)
     } else if (scheduleType) {
       scheduleTiming = `${scheduleType.charAt(0).toUpperCase() + scheduleType.slice(1)}`
     }
@@ -142,8 +157,14 @@ export function ScheduleConfig({
       <>
         <div className='truncate font-normal text-sm'>{scheduleTiming}</div>
         <div className='text-muted-foreground text-xs'>
-          <div>Next run: {formatDateTime(new Date(nextRunAt), timezone)}</div>
-          {lastRanAt && <div>Last run: {formatDateTime(new Date(lastRanAt), timezone)}</div>}
+          <div>
+            Next run: {formatDateTime(new Date(scheduleData.nextRunAt), scheduleData.timezone)}
+          </div>
+          {scheduleData.lastRanAt && (
+            <div>
+              Last run: {formatDateTime(new Date(scheduleData.lastRanAt), scheduleData.timezone)}
+            </div>
+          )}
         </div>
       </>
     )
@@ -154,16 +175,11 @@ export function ScheduleConfig({
     setIsModalOpen(true)
   }
 
-  const handleCloseModal = () => {
+  const handleCloseModal = useCallback(() => {
     setIsModalOpen(false)
-    // Force a refresh when closing the modal
-    // Use a small timeout to ensure backend updates are complete
-    setTimeout(() => {
-      setRefreshCounter((prev) => prev + 1)
-    }, 500)
-  }
+  }, [])
 
-  const handleSaveSchedule = async (): Promise<boolean> => {
+  const handleSaveSchedule = useCallback(async (): Promise<boolean> => {
     if (isPreview || disabled) return false
 
     setIsSaving(true)
@@ -246,17 +262,24 @@ export function ScheduleConfig({
       logger.debug('Schedule save response:', responseData)
 
       // 5. Update our local state with the response data
-      if (responseData.cronExpression) {
-        setCronExpression(responseData.cronExpression)
+      if (responseData.cronExpression || responseData.nextRunAt) {
+        setScheduleData((prev) => ({
+          ...prev,
+          cronExpression: responseData.cronExpression || prev.cronExpression,
+          nextRunAt:
+            typeof responseData.nextRunAt === 'string'
+              ? responseData.nextRunAt
+              : responseData.nextRunAt?.toISOString?.() || prev.nextRunAt,
+        }))
       }
 
-      if (responseData.nextRunAt) {
-        setNextRunAt(
-          typeof responseData.nextRunAt === 'string'
-            ? responseData.nextRunAt
-            : responseData.nextRunAt.toISOString?.() || responseData.nextRunAt
-        )
-      }
+      // 6. Dispatch custom event to notify parent workflow-block component to refetch schedule info
+      // This ensures the badge updates immediately after saving
+      const event = new CustomEvent('schedule-updated', {
+        detail: { workflowId, blockId },
+      })
+      window.dispatchEvent(event)
+      logger.debug('Dispatched schedule-updated event', { workflowId, blockId })
 
       // 6. Update the schedule status and trigger a workflow update
       // Note: Global schedule status is managed at a higher level
@@ -266,15 +289,8 @@ export function ScheduleConfig({
       workflowStore.updateLastSaved()
       workflowStore.triggerUpdate()
 
-      // 8. Force a refresh to update the UI
-      // Use a timeout to ensure the API changes are completed
-      setTimeout(() => {
-        logger.debug('Refreshing schedule information after save')
-        setRefreshCounter((prev) => prev + 1)
-
-        // Make a separate API call to ensure we get the latest schedule info
-        checkSchedule()
-      }, 500)
+      // 8. Refetch the schedule to update local state
+      await fetchSchedule()
 
       return true
     } catch (error) {
@@ -284,10 +300,10 @@ export function ScheduleConfig({
     } finally {
       setIsSaving(false)
     }
-  }
+  }, [workflowId, blockId, isScheduleTriggerBlock, setStartWorkflow, fetchSchedule])
 
-  const handleDeleteSchedule = async (): Promise<boolean> => {
-    if (isPreview || !scheduleId || disabled) return false
+  const handleDeleteSchedule = useCallback(async (): Promise<boolean> => {
+    if (isPreview || !scheduleData.id || disabled) return false
 
     setIsDeleting(true)
     try {
@@ -315,7 +331,7 @@ export function ScheduleConfig({
       }
 
       // 4. Make the DELETE API call to remove the schedule
-      const response = await fetch(`/api/schedules/${scheduleId}`, {
+      const response = await fetch(`/api/schedules/${scheduleData.id}`, {
         method: 'DELETE',
       })
 
@@ -326,14 +342,23 @@ export function ScheduleConfig({
       }
 
       // 5. Clear schedule state
-      setScheduleId(null)
-      setNextRunAt(null)
-      setLastRanAt(null)
-      setCronExpression(null)
+      setScheduleData({
+        id: null,
+        nextRunAt: null,
+        lastRanAt: null,
+        cronExpression: null,
+        timezone: 'UTC',
+      })
 
       // 6. Update schedule status and refresh UI
       // Note: Global schedule status is managed at a higher level
-      setRefreshCounter((prev) => prev + 1)
+
+      // 7. Dispatch custom event to notify parent workflow-block component
+      const event = new CustomEvent('schedule-updated', {
+        detail: { workflowId, blockId },
+      })
+      window.dispatchEvent(event)
+      logger.debug('Dispatched schedule-updated event after delete', { workflowId, blockId })
 
       return true
     } catch (error) {
@@ -343,10 +368,18 @@ export function ScheduleConfig({
     } finally {
       setIsDeleting(false)
     }
-  }
+  }, [
+    scheduleData.id,
+    isPreview,
+    disabled,
+    isScheduleTriggerBlock,
+    setStartWorkflow,
+    workflowId,
+    blockId,
+  ])
 
   // Check if the schedule is active
-  const isScheduleActive = !!scheduleId && !!nextRunAt
+  const isScheduleActive = !!scheduleData.id && !!scheduleData.nextRunAt
 
   return (
     <div className='w-full' onClick={(e) => e.stopPropagation()}>
@@ -399,7 +432,7 @@ export function ScheduleConfig({
           blockId={blockId}
           onSave={handleSaveSchedule}
           onDelete={handleDeleteSchedule}
-          scheduleId={scheduleId}
+          scheduleId={scheduleData.id}
         />
       </Dialog>
     </div>
diff --git a/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/workflow-block/workflow-block.tsx b/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/workflow-block/workflow-block.tsx
index 09ef321ee..4891fceab 100644
--- a/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/workflow-block/workflow-block.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/workflow-block/workflow-block.tsx
@@ -280,83 +280,59 @@ export const WorkflowBlock = memo(
       }
     }
 
-    const fetchScheduleInfo = async (workflowId: string) => {
-      if (!workflowId) return
-
-      try {
-        setIsLoadingScheduleInfo(true)
-
-        // For schedule trigger blocks, always include the blockId parameter
-        const url = new URL('/api/schedules', window.location.origin)
-        url.searchParams.set('workflowId', workflowId)
-        url.searchParams.set('mode', 'schedule')
-        url.searchParams.set('blockId', id) // Always include blockId for schedule blocks
-
-        const response = await fetch(url.toString(), {
-          cache: 'no-store',
-          headers: {
-            'Cache-Control': 'no-cache',
-          },
-        })
-
-        if (!response.ok) {
-          setScheduleInfo(null)
-          return
-        }
-
-        const data = await response.json()
-
-        if (!data.schedule) {
-          setScheduleInfo(null)
-          return
-        }
-
-        let scheduleTiming = 'Unknown schedule'
-        if (data.schedule.cronExpression) {
-          scheduleTiming = parseCronToHumanReadable(data.schedule.cronExpression)
-        }
-
-        const baseInfo = {
-          scheduleTiming,
-          nextRunAt: data.schedule.nextRunAt as string | null,
-          lastRanAt: data.schedule.lastRanAt as string | null,
-          timezone: data.schedule.timezone || 'UTC',
-          status: data.schedule.status as string,
-          isDisabled: data.schedule.status === 'disabled',
-          id: data.schedule.id as string,
-        }
+    const fetchScheduleInfo = useCallback(
+      async (workflowId: string) => {
+        if (!workflowId) return
 
         try {
-          const statusRes = await fetch(`/api/schedules/${baseInfo.id}/status`, {
+          setIsLoadingScheduleInfo(true)
+
+          const params = new URLSearchParams({
+            workflowId,
+            mode: 'schedule',
+            blockId: id,
+          })
+
+          const response = await fetch(`/api/schedules?${params}`, {
             cache: 'no-store',
             headers: { 'Cache-Control': 'no-cache' },
           })
 
-          if (statusRes.ok) {
-            const statusData = await statusRes.json()
-            setScheduleInfo({
-              scheduleTiming: baseInfo.scheduleTiming,
-              nextRunAt: statusData.nextRunAt ?? baseInfo.nextRunAt,
-              lastRanAt: statusData.lastRanAt ?? baseInfo.lastRanAt,
-              timezone: baseInfo.timezone,
-              status: statusData.status ?? baseInfo.status,
-              isDisabled: statusData.isDisabled ?? baseInfo.isDisabled,
-              id: baseInfo.id,
-            })
+          if (!response.ok) {
+            setScheduleInfo(null)
             return
           }
-        } catch (err) {
-          logger.error('Error fetching schedule status:', err)
-        }
 
-        setScheduleInfo(baseInfo)
-      } catch (error) {
-        logger.error('Error fetching schedule info:', error)
-        setScheduleInfo(null)
-      } finally {
-        setIsLoadingScheduleInfo(false)
-      }
-    }
+          const data = await response.json()
+
+          if (!data.schedule) {
+            setScheduleInfo(null)
+            return
+          }
+
+          const schedule = data.schedule
+          const scheduleTimezone = schedule.timezone || 'UTC'
+
+          setScheduleInfo({
+            scheduleTiming: schedule.cronExpression
+              ? parseCronToHumanReadable(schedule.cronExpression, scheduleTimezone)
+              : 'Unknown schedule',
+            nextRunAt: schedule.nextRunAt,
+            lastRanAt: schedule.lastRanAt,
+            timezone: scheduleTimezone,
+            status: schedule.status,
+            isDisabled: schedule.status === 'disabled',
+            id: schedule.id,
+          })
+        } catch (error) {
+          logger.error('Error fetching schedule info:', error)
+          setScheduleInfo(null)
+        } finally {
+          setIsLoadingScheduleInfo(false)
+        }
+      },
+      [id]
+    )
 
     useEffect(() => {
       if (type === 'schedule' && currentWorkflowId) {
@@ -366,11 +342,25 @@ export const WorkflowBlock = memo(
         setIsLoadingScheduleInfo(false) // Reset loading state when not a schedule block
       }
 
-      // Cleanup function to reset loading state when component unmounts or workflow changes
+      // Listen for schedule updates from the schedule-config component
+      const handleScheduleUpdate = (event: CustomEvent) => {
+        // Check if the update is for this workflow and block
+        if (event.detail?.workflowId === currentWorkflowId && event.detail?.blockId === id) {
+          logger.debug('Schedule update event received, refetching schedule info')
+          if (type === 'schedule') {
+            fetchScheduleInfo(currentWorkflowId)
+          }
+        }
+      }
+
+      window.addEventListener('schedule-updated', handleScheduleUpdate as EventListener)
+
+      // Cleanup function to reset loading state and remove listener
       return () => {
         setIsLoadingScheduleInfo(false)
+        window.removeEventListener('schedule-updated', handleScheduleUpdate as EventListener)
       }
-    }, [isStarterBlock, isTriggerBlock, type, currentWorkflowId])
+    }, [type, currentWorkflowId, id, fetchScheduleInfo])
 
     // Get webhook information for the tooltip
     useEffect(() => {
diff --git a/apps/sim/background/schedule-execution.ts b/apps/sim/background/schedule-execution.ts
index 691f8255a..24709b432 100644
--- a/apps/sim/background/schedule-execution.ts
+++ b/apps/sim/background/schedule-execution.ts
@@ -49,8 +49,14 @@ function calculateNextRunTime(
   const scheduleType = getSubBlockValue(scheduleBlock, 'scheduleType')
   const scheduleValues = getScheduleTimeValues(scheduleBlock)
 
+  // Get timezone from schedule configuration (default to UTC)
+  const timezone = scheduleValues.timezone || 'UTC'
+
   if (schedule.cronExpression) {
-    const cron = new Cron(schedule.cronExpression)
+    // Use Croner with timezone support for accurate scheduling
+    const cron = new Cron(schedule.cronExpression, {
+      timezone,
+    })
     const nextDate = cron.nextRun()
     if (!nextDate) throw new Error('Invalid cron expression or no future occurrences')
     return nextDate
diff --git a/apps/sim/lib/schedules/utils.test.ts b/apps/sim/lib/schedules/utils.test.ts
index 5e3b81810..1e9033de8 100644
--- a/apps/sim/lib/schedules/utils.test.ts
+++ b/apps/sim/lib/schedules/utils.test.ts
@@ -223,7 +223,7 @@ describe('Schedule Utilities', () => {
       vi.useRealTimers()
     })
 
-    it.concurrent('should calculate next run for minutes schedule', () => {
+    it.concurrent('should calculate next run for minutes schedule using Croner', () => {
       const scheduleValues = {
         scheduleTime: '',
         scheduleStartAt: '',
@@ -244,14 +244,14 @@ describe('Schedule Utilities', () => {
       expect(nextRun instanceof Date).toBe(true)
       expect(nextRun > new Date()).toBe(true)
 
-      // Check minute is a multiple of the interval
-      expect(nextRun.getMinutes() % 15).toBe(0)
+      // Croner will calculate based on the cron expression */15 * * * *
+      // The exact minute depends on Croner's calculation
     })
 
-    it.concurrent('should respect scheduleTime for minutes schedule', () => {
+    it.concurrent('should handle scheduleStartAt with scheduleTime', () => {
       const scheduleValues = {
         scheduleTime: '14:30', // Specific start time
-        scheduleStartAt: '',
+        scheduleStartAt: '2025-04-15', // Future date
         timezone: 'UTC',
         minutesInterval: 15,
         hourlyMinute: 0,
@@ -265,12 +265,13 @@ describe('Schedule Utilities', () => {
 
       const nextRun = calculateNextRunTime('minutes', scheduleValues)
 
-      // Should be 14:30
-      expect(nextRun.getHours()).toBe(14)
-      expect(nextRun.getMinutes()).toBe(30)
+      // Should return the future start date with time
+      expect(nextRun.getFullYear()).toBe(2025)
+      expect(nextRun.getMonth()).toBe(3) // April
+      expect(nextRun.getDate()).toBe(15)
     })
 
-    it.concurrent('should calculate next run for hourly schedule', () => {
+    it.concurrent('should calculate next run for hourly schedule using Croner', () => {
       const scheduleValues = {
         scheduleTime: '',
         scheduleStartAt: '',
@@ -287,13 +288,14 @@ describe('Schedule Utilities', () => {
 
       const nextRun = calculateNextRunTime('hourly', scheduleValues)
 
-      // Just verify it's a valid future date with the right minute
+      // Verify it's a valid future date using Croner's calculation
       expect(nextRun instanceof Date).toBe(true)
       expect(nextRun > new Date()).toBe(true)
+      // Croner calculates based on cron "30 * * * *"
       expect(nextRun.getMinutes()).toBe(30)
     })
 
-    it.concurrent('should calculate next run for daily schedule', () => {
+    it.concurrent('should calculate next run for daily schedule using Croner with timezone', () => {
       const scheduleValues = {
         scheduleTime: '',
         scheduleStartAt: '',
@@ -310,88 +312,96 @@ describe('Schedule Utilities', () => {
 
       const nextRun = calculateNextRunTime('daily', scheduleValues)
 
-      // Verify it's a future date at exactly 9:00
+      // Verify it's a future date at exactly 9:00 UTC using Croner
       expect(nextRun instanceof Date).toBe(true)
       expect(nextRun > new Date()).toBe(true)
-      expect(nextRun.getHours()).toBe(9)
-      expect(nextRun.getMinutes()).toBe(0)
+      expect(nextRun.getUTCHours()).toBe(9)
+      expect(nextRun.getUTCMinutes()).toBe(0)
     })
 
-    it.concurrent('should calculate next run for weekly schedule', () => {
-      const scheduleValues = {
-        scheduleTime: '',
-        scheduleStartAt: '',
-        timezone: 'UTC',
-        minutesInterval: 15,
-        hourlyMinute: 0,
-        dailyTime: [9, 0] as [number, number],
-        weeklyDay: 1, // Monday
-        weeklyTime: [10, 0] as [number, number],
-        monthlyDay: 1,
-        monthlyTime: [9, 0] as [number, number],
-        cronExpression: null,
+    it.concurrent(
+      'should calculate next run for weekly schedule using Croner with timezone',
+      () => {
+        const scheduleValues = {
+          scheduleTime: '',
+          scheduleStartAt: '',
+          timezone: 'UTC',
+          minutesInterval: 15,
+          hourlyMinute: 0,
+          dailyTime: [9, 0] as [number, number],
+          weeklyDay: 1, // Monday
+          weeklyTime: [10, 0] as [number, number],
+          monthlyDay: 1,
+          monthlyTime: [9, 0] as [number, number],
+          cronExpression: null,
+        }
+
+        const nextRun = calculateNextRunTime('weekly', scheduleValues)
+
+        // Should be next Monday at 10:00 AM UTC using Croner
+        expect(nextRun.getUTCDay()).toBe(1) // Monday
+        expect(nextRun.getUTCHours()).toBe(10)
+        expect(nextRun.getUTCMinutes()).toBe(0)
       }
+    )
 
-      const nextRun = calculateNextRunTime('weekly', scheduleValues)
+    it.concurrent(
+      'should calculate next run for monthly schedule using Croner with timezone',
+      () => {
+        const scheduleValues = {
+          scheduleTime: '',
+          scheduleStartAt: '',
+          timezone: 'UTC',
+          minutesInterval: 15,
+          hourlyMinute: 0,
+          dailyTime: [9, 0] as [number, number],
+          weeklyDay: 1,
+          weeklyTime: [9, 0] as [number, number],
+          monthlyDay: 15,
+          monthlyTime: [14, 30] as [number, number],
+          cronExpression: null,
+        }
 
-      // Should be next Monday at 10:00 AM
-      expect(nextRun.getDay()).toBe(1) // Monday
-      expect(nextRun.getHours()).toBe(10)
-      expect(nextRun.getMinutes()).toBe(0)
-    })
+        const nextRun = calculateNextRunTime('monthly', scheduleValues)
 
-    it.concurrent('should calculate next run for monthly schedule', () => {
-      const scheduleValues = {
-        scheduleTime: '',
-        scheduleStartAt: '',
-        timezone: 'UTC',
-        minutesInterval: 15,
-        hourlyMinute: 0,
-        dailyTime: [9, 0] as [number, number],
-        weeklyDay: 1,
-        weeklyTime: [9, 0] as [number, number],
-        monthlyDay: 15,
-        monthlyTime: [14, 30] as [number, number],
-        cronExpression: null,
+        // Current date is 2025-04-12 12:00, so next run should be 2025-04-15 14:30 UTC using Croner
+        expect(nextRun.getFullYear()).toBe(2025)
+        expect(nextRun.getUTCMonth()).toBe(3) // April (0-indexed)
+        expect(nextRun.getUTCDate()).toBe(15)
+        expect(nextRun.getUTCHours()).toBe(14)
+        expect(nextRun.getUTCMinutes()).toBe(30)
       }
+    )
 
-      const nextRun = calculateNextRunTime('monthly', scheduleValues)
+    it.concurrent(
+      'should work with lastRanAt parameter (though Croner calculates independently)',
+      () => {
+        const scheduleValues = {
+          scheduleTime: '',
+          scheduleStartAt: '',
+          timezone: 'UTC',
+          minutesInterval: 15,
+          hourlyMinute: 0,
+          dailyTime: [9, 0] as [number, number],
+          weeklyDay: 1,
+          weeklyTime: [9, 0] as [number, number],
+          monthlyDay: 1,
+          monthlyTime: [9, 0] as [number, number],
+          cronExpression: null,
+        }
 
-      // Current date is 2025-04-12 12:00, so next run should be 2025-04-15 14:30
-      expect(nextRun.getFullYear()).toBe(2025)
-      expect(nextRun.getMonth()).toBe(3) // April (0-indexed)
-      expect(nextRun.getDate()).toBe(15)
-      expect(nextRun.getHours()).toBe(14)
-      expect(nextRun.getMinutes()).toBe(30)
-    })
+        // Last ran 10 minutes ago
+        const lastRanAt = new Date()
+        lastRanAt.setMinutes(lastRanAt.getMinutes() - 10)
 
-    it.concurrent('should consider lastRanAt for better interval calculation', () => {
-      const scheduleValues = {
-        scheduleTime: '',
-        scheduleStartAt: '',
-        timezone: 'UTC',
-        minutesInterval: 15,
-        hourlyMinute: 0,
-        dailyTime: [9, 0] as [number, number],
-        weeklyDay: 1,
-        weeklyTime: [9, 0] as [number, number],
-        monthlyDay: 1,
-        monthlyTime: [9, 0] as [number, number],
-        cronExpression: null,
+        const nextRun = calculateNextRunTime('minutes', scheduleValues, lastRanAt)
+
+        // With Croner, it calculates based on cron expression, not lastRanAt
+        // Just verify we get a future date
+        expect(nextRun instanceof Date).toBe(true)
+        expect(nextRun > new Date()).toBe(true)
       }
-
-      // Last ran 10 minutes ago
-      const lastRanAt = new Date()
-      lastRanAt.setMinutes(lastRanAt.getMinutes() - 10)
-
-      const nextRun = calculateNextRunTime('minutes', scheduleValues, lastRanAt)
-
-      // Should be 5 minutes from the last run (15 min interval)
-      const expectedNextRun = new Date(lastRanAt)
-      expectedNextRun.setMinutes(expectedNextRun.getMinutes() + 15)
-
-      expect(nextRun.getMinutes()).toBe(expectedNextRun.getMinutes())
-    })
+    )
 
     it.concurrent('should respect future scheduleStartAt date', () => {
       const scheduleValues = {
@@ -453,6 +463,12 @@ describe('Schedule Utilities', () => {
       })
     })
 
+    it.concurrent('should validate cron expressions with timezone', () => {
+      const result = validateCronExpression('0 9 * * *', 'America/Los_Angeles')
+      expect(result.isValid).toBe(true)
+      expect(result.nextRun).toBeInstanceOf(Date)
+    })
+
     it.concurrent('should reject invalid cron expressions', () => {
       expect(validateCronExpression('invalid')).toEqual({
         isValid: false,
@@ -482,27 +498,181 @@ describe('Schedule Utilities', () => {
   })
 
   describe('parseCronToHumanReadable', () => {
-    it.concurrent('should parse common cron patterns', () => {
+    it.concurrent('should parse common cron patterns using cronstrue', () => {
+      // cronstrue produces "Every minute" for '* * * * *'
       expect(parseCronToHumanReadable('* * * * *')).toBe('Every minute')
+
+      // cronstrue produces "Every 15 minutes" for '*/15 * * * *'
       expect(parseCronToHumanReadable('*/15 * * * *')).toBe('Every 15 minutes')
-      expect(parseCronToHumanReadable('30 * * * *')).toBe('Hourly at 30 minutes past the hour')
-      expect(parseCronToHumanReadable('0 9 * * *')).toBe('Daily at 9:00 AM')
-      expect(parseCronToHumanReadable('30 14 * * *')).toBe('Daily at 2:30 PM')
-      expect(parseCronToHumanReadable('0 9 * * 1')).toMatch(/Monday at 9:00 AM/)
-      expect(parseCronToHumanReadable('30 14 15 * *')).toMatch(/Monthly on the 15th at 2:30 PM/)
+
+      // cronstrue produces "At 30 minutes past the hour" for '30 * * * *'
+      expect(parseCronToHumanReadable('30 * * * *')).toContain('30 minutes past the hour')
+
+      // cronstrue produces "At 09:00 AM" for '0 9 * * *'
+      expect(parseCronToHumanReadable('0 9 * * *')).toContain('09:00 AM')
+
+      // cronstrue produces "At 02:30 PM" for '30 14 * * *'
+      expect(parseCronToHumanReadable('30 14 * * *')).toContain('02:30 PM')
+
+      // cronstrue produces "At 09:00 AM, only on Monday" for '0 9 * * 1'
+      expect(parseCronToHumanReadable('0 9 * * 1')).toContain('Monday')
+
+      // cronstrue produces "At 02:30 PM, on day 15 of the month" for '30 14 15 * *'
+      expect(parseCronToHumanReadable('30 14 15 * *')).toContain('15')
     })
 
-    it.concurrent('should handle complex patterns', () => {
-      // Test with various combinations
-      expect(parseCronToHumanReadable('* */2 * * *')).toMatch(/Runs/)
-      expect(parseCronToHumanReadable('0 9 * * 1-5')).toMatch(/Runs/)
-      expect(parseCronToHumanReadable('0 9 1,15 * *')).toMatch(/Runs/)
+    it.concurrent('should include timezone information when provided', () => {
+      const resultPT = parseCronToHumanReadable('0 9 * * *', 'America/Los_Angeles')
+      expect(resultPT).toContain('(PT)')
+      expect(resultPT).toContain('09:00 AM')
+
+      const resultET = parseCronToHumanReadable('30 14 * * *', 'America/New_York')
+      expect(resultET).toContain('(ET)')
+      expect(resultET).toContain('02:30 PM')
+
+      const resultUTC = parseCronToHumanReadable('0 12 * * *', 'UTC')
+      expect(resultUTC).not.toContain('(UTC)') // UTC should not be explicitly shown
     })
 
-    it.concurrent('should return a fallback for unrecognized patterns', () => {
-      const result = parseCronToHumanReadable('*/10 */6 31 2 *') // Invalid (Feb 31)
-      // Just check that we get something back that's not empty
-      expect(result.length).toBeGreaterThan(5)
+    it.concurrent('should handle complex patterns with cronstrue', () => {
+      // cronstrue can handle complex patterns better than our custom parser
+      const result1 = parseCronToHumanReadable('0 9 * * 1-5')
+      expect(result1).toContain('Monday through Friday')
+
+      const result2 = parseCronToHumanReadable('0 9 1,15 * *')
+      expect(result2).toContain('day 1 and 15')
+    })
+
+    it.concurrent('should return a fallback for invalid patterns', () => {
+      const result = parseCronToHumanReadable('invalid cron')
+      // Should fallback to "Schedule: <expression>"
+      expect(result).toContain('Schedule:')
+      expect(result).toContain('invalid cron')
+    })
+  })
+
+  describe('Timezone-aware scheduling with Croner', () => {
+    it.concurrent('should calculate daily schedule in Pacific Time correctly', () => {
+      const scheduleValues = {
+        scheduleTime: '',
+        scheduleStartAt: '',
+        timezone: 'America/Los_Angeles',
+        minutesInterval: 15,
+        hourlyMinute: 0,
+        dailyTime: [9, 0] as [number, number], // 9 AM Pacific
+        weeklyDay: 1,
+        weeklyTime: [9, 0] as [number, number],
+        monthlyDay: 1,
+        monthlyTime: [9, 0] as [number, number],
+        cronExpression: null,
+      }
+
+      const nextRun = calculateNextRunTime('daily', scheduleValues)
+
+      // 9 AM Pacific should be 16:00 or 17:00 UTC depending on DST
+      // Croner handles this automatically
+      expect(nextRun instanceof Date).toBe(true)
+      expect(nextRun > new Date()).toBe(true)
+    })
+
+    it.concurrent('should handle DST transition for schedules', () => {
+      // Set a date during DST transition in March
+      vi.useFakeTimers()
+      vi.setSystemTime(new Date('2025-03-08T10:00:00.000Z')) // Before DST
+
+      const scheduleValues = {
+        scheduleTime: '',
+        scheduleStartAt: '',
+        timezone: 'America/New_York',
+        minutesInterval: 15,
+        hourlyMinute: 0,
+        dailyTime: [14, 0] as [number, number], // 2 PM Eastern
+        weeklyDay: 1,
+        weeklyTime: [14, 0] as [number, number],
+        monthlyDay: 1,
+        monthlyTime: [14, 0] as [number, number],
+        cronExpression: null,
+      }
+
+      const nextRun = calculateNextRunTime('daily', scheduleValues)
+
+      // Croner should handle DST transition correctly
+      expect(nextRun instanceof Date).toBe(true)
+      expect(nextRun > new Date()).toBe(true)
+
+      vi.useRealTimers()
+    })
+
+    it.concurrent('should calculate weekly schedule in Tokyo timezone', () => {
+      const scheduleValues = {
+        scheduleTime: '',
+        scheduleStartAt: '',
+        timezone: 'Asia/Tokyo',
+        minutesInterval: 15,
+        hourlyMinute: 0,
+        dailyTime: [9, 0] as [number, number],
+        weeklyDay: 1, // Monday
+        weeklyTime: [10, 0] as [number, number], // 10 AM Japan Time
+        monthlyDay: 1,
+        monthlyTime: [9, 0] as [number, number],
+        cronExpression: null,
+      }
+
+      const nextRun = calculateNextRunTime('weekly', scheduleValues)
+
+      // Verify it's a valid future date
+      // Tokyo is UTC+9, so 10 AM JST = 1 AM UTC
+      expect(nextRun instanceof Date).toBe(true)
+      expect(nextRun > new Date()).toBe(true)
+    })
+
+    it.concurrent('should handle custom cron with timezone', () => {
+      const scheduleValues = {
+        scheduleTime: '',
+        scheduleStartAt: '',
+        timezone: 'Europe/London',
+        minutesInterval: 15,
+        hourlyMinute: 0,
+        dailyTime: [9, 0] as [number, number],
+        weeklyDay: 1,
+        weeklyTime: [9, 0] as [number, number],
+        monthlyDay: 1,
+        monthlyTime: [9, 0] as [number, number],
+        cronExpression: '30 15 * * *', // 3:30 PM London time
+      }
+
+      const nextRun = calculateNextRunTime('custom', scheduleValues)
+
+      // Verify it's a valid future date
+      expect(nextRun instanceof Date).toBe(true)
+      expect(nextRun > new Date()).toBe(true)
+    })
+
+    it.concurrent('should handle monthly schedule on last day of month', () => {
+      vi.useFakeTimers()
+      vi.setSystemTime(new Date('2025-02-15T12:00:00.000Z'))
+
+      const scheduleValues = {
+        scheduleTime: '',
+        scheduleStartAt: '',
+        timezone: 'America/Chicago',
+        minutesInterval: 15,
+        hourlyMinute: 0,
+        dailyTime: [9, 0] as [number, number],
+        weeklyDay: 1,
+        weeklyTime: [9, 0] as [number, number],
+        monthlyDay: 28, // Last day of Feb (non-leap year)
+        monthlyTime: [12, 0] as [number, number], // Noon Central
+        cronExpression: null,
+      }
+
+      const nextRun = calculateNextRunTime('monthly', scheduleValues)
+
+      // Should calculate Feb 28 at noon Central time
+      expect(nextRun.getUTCDate()).toBe(28)
+      expect(nextRun.getUTCMonth()).toBe(1) // February
+
+      vi.useRealTimers()
     })
   })
 
diff --git a/apps/sim/lib/schedules/utils.ts b/apps/sim/lib/schedules/utils.ts
index 0745f8d13..c66003ce6 100644
--- a/apps/sim/lib/schedules/utils.ts
+++ b/apps/sim/lib/schedules/utils.ts
@@ -1,4 +1,5 @@
 import { Cron } from 'croner'
+import cronstrue from 'cronstrue'
 import { createLogger } from '@/lib/logs/console/logger'
 import { formatDateTime } from '@/lib/utils'
 
@@ -7,9 +8,13 @@ const logger = createLogger('ScheduleUtils')
 /**
  * Validates a cron expression and returns validation results
  * @param cronExpression - The cron expression to validate
+ * @param timezone - Optional IANA timezone string (e.g., 'America/Los_Angeles'). Defaults to 'UTC'
  * @returns Validation result with isValid flag, error message, and next run date
  */
-export function validateCronExpression(cronExpression: string): {
+export function validateCronExpression(
+  cronExpression: string,
+  timezone?: string
+): {
   isValid: boolean
   error?: string
   nextRun?: Date
@@ -22,7 +27,8 @@ export function validateCronExpression(cronExpression: string): {
   }
 
   try {
-    const cron = new Cron(cronExpression)
+    // Validate with timezone if provided for accurate next run calculation
+    const cron = new Cron(cronExpression, timezone ? { timezone } : undefined)
     const nextRun = cron.nextRun()
 
     if (!nextRun) {
@@ -267,6 +273,21 @@ export function createDateWithTimezone(
 
 /**
  * Generate cron expression based on schedule type and values
+ *
+ * IMPORTANT: The generated cron expressions use local time values (hours/minutes)
+ * from the user's configured timezone. When used with Croner, pass the timezone
+ * option to ensure proper scheduling:
+ *
+ * Example:
+ *   const cronExpr = generateCronExpression('daily', { dailyTime: [14, 30], timezone: 'America/Los_Angeles' })
+ *   const cron = new Cron(cronExpr, { timezone: 'America/Los_Angeles' })
+ *
+ * This will schedule the job at 2:30 PM Pacific Time, which Croner will correctly
+ * convert to the appropriate UTC time, handling DST transitions automatically.
+ *
+ * @param scheduleType - Type of schedule (minutes, hourly, daily, weekly, monthly, custom)
+ * @param scheduleValues - Object containing schedule configuration including timezone
+ * @returns Cron expression string representing the schedule in local time
  */
 export function generateCronExpression(
   scheduleType: string,
@@ -308,6 +329,7 @@ export function generateCronExpression(
 
 /**
  * Calculate the next run time based on schedule configuration
+ * Uses Croner library with timezone support for accurate scheduling across timezones and DST transitions
  * @param scheduleType - Type of schedule (minutes, hourly, daily, etc)
  * @param scheduleValues - Object with schedule configuration values
  * @param lastRanAt - Optional last execution time
@@ -398,270 +420,83 @@ export function calculateNextRunTime(
     }
   }
 
-  // If we have a scheduleTime (but no future scheduleStartAt), use it for today
-  const scheduleTimeOverride = scheduleValues.scheduleTime
-    ? parseTimeString(scheduleValues.scheduleTime)
-    : null
+  // For recurring schedules, use Croner with timezone support
+  // This ensures proper timezone handling and DST transitions
+  try {
+    const cronExpression = generateCronExpression(scheduleType, scheduleValues)
+    logger.debug(`Using cron expression: ${cronExpression} with timezone: ${timezone}`)
 
-  // Create next run date based on the current date
-  const nextRun = new Date(baseDate)
+    // Create Croner instance with timezone support
+    const cron = new Cron(cronExpression, {
+      timezone,
+    })
 
-  switch (scheduleType) {
-    case 'minutes': {
-      const { minutesInterval } = scheduleValues
+    const nextDate = cron.nextRun()
 
-      // If we have a time override, use it
-      if (scheduleTimeOverride) {
-        const [hours, minutes] = scheduleTimeOverride
-        nextRun.setHours(hours, minutes, 0, 0)
-
-        // Add intervals until we're in the future
-        while (nextRun <= new Date()) {
-          nextRun.setMinutes(nextRun.getMinutes() + minutesInterval)
-        }
-        return nextRun
-      }
-
-      // For subsequent runs after lastRanAt
-      if (lastRanAt) {
-        const baseTime = new Date(lastRanAt)
-        nextRun.setTime(baseTime.getTime())
-        nextRun.setMinutes(nextRun.getMinutes() + minutesInterval, 0, 0)
-
-        // Make sure we're in the future
-        while (nextRun <= new Date()) {
-          nextRun.setMinutes(nextRun.getMinutes() + minutesInterval)
-        }
-        return nextRun
-      }
-
-      // Calculate next boundary for minutes
-      const now = new Date()
-      const currentMinutes = now.getMinutes()
-      const nextIntervalBoundary = Math.ceil(currentMinutes / minutesInterval) * minutesInterval
-      nextRun.setMinutes(nextIntervalBoundary, 0, 0)
-
-      // If we're past this time but haven't reached baseDate, adjust
-      if (nextRun <= now) {
-        nextRun.setMinutes(nextRun.getMinutes() + minutesInterval)
-      }
-
-      return nextRun
+    if (!nextDate) {
+      throw new Error(`No next run date calculated for cron: ${cronExpression}`)
     }
 
-    case 'hourly': {
-      // Use the override time if available, otherwise use hourly config
-      const [targetHours, _] = scheduleTimeOverride || [nextRun.getHours(), 0]
-      const targetMinutes = scheduleValues.hourlyMinute
-
-      nextRun.setHours(targetHours, targetMinutes, 0, 0)
-
-      // If we're in the past relative to now (not baseDate), move to next hour
-      if (nextRun <= new Date()) {
-        nextRun.setHours(nextRun.getHours() + 1)
-      }
-
-      return nextRun
-    }
-
-    case 'daily': {
-      // Use either schedule override or daily time values
-      const [hours, minutes] = scheduleTimeOverride || scheduleValues.dailyTime
-
-      nextRun.setHours(hours, minutes, 0, 0)
-
-      // If we're in the past relative to now (not baseDate), move to tomorrow
-      if (nextRun <= new Date()) {
-        nextRun.setDate(nextRun.getDate() + 1)
-      }
-
-      return nextRun
-    }
-
-    case 'weekly': {
-      // Use either schedule override or weekly time values
-      const [hours, minutes] = scheduleTimeOverride || scheduleValues.weeklyTime
-
-      nextRun.setHours(hours, minutes, 0, 0)
-
-      // Add days until we reach the target day in the future
-      while (nextRun.getDay() !== scheduleValues.weeklyDay || nextRun <= new Date()) {
-        nextRun.setDate(nextRun.getDate() + 1)
-      }
-
-      return nextRun
-    }
-
-    case 'monthly': {
-      // Use either schedule override or monthly time values
-      const [hours, minutes] = scheduleTimeOverride || scheduleValues.monthlyTime
-      const { monthlyDay } = scheduleValues
-
-      nextRun.setDate(monthlyDay)
-      nextRun.setHours(hours, minutes, 0, 0)
-
-      // If we're in the past relative to now (not baseDate), move to next month
-      if (nextRun <= new Date()) {
-        nextRun.setMonth(nextRun.getMonth() + 1)
-      }
-
-      return nextRun
-    }
-
-    default:
-      throw new Error(`Unsupported schedule type: ${scheduleType}`)
+    logger.debug(`Next run calculated: ${nextDate.toISOString()}`)
+    return nextDate
+  } catch (error) {
+    logger.error('Error calculating next run with Croner:', error)
+    throw new Error(
+      `Failed to calculate next run time for schedule type ${scheduleType}: ${error instanceof Error ? error.message : String(error)}`
+    )
   }
 }
 
 /**
- * Converts a cron expression to a human-readable string format
+ * Helper function to get a friendly timezone abbreviation
  */
-export const parseCronToHumanReadable = (cronExpression: string): string => {
-  // Parse the cron parts
-  const parts = cronExpression.split(' ')
-
-  // Handle standard patterns
-  if (cronExpression === '* * * * *') {
-    return 'Every minute'
+function getTimezoneAbbreviation(timezone: string): string {
+  const timezoneMap: Record<string, string> = {
+    'America/Los_Angeles': 'PT',
+    'America/Denver': 'MT',
+    'America/Chicago': 'CT',
+    'America/New_York': 'ET',
+    'Europe/London': 'GMT/BST',
+    'Europe/Paris': 'CET/CEST',
+    'Asia/Tokyo': 'JST',
+    'Asia/Singapore': 'SGT',
+    'Australia/Sydney': 'AEDT/AEST',
+    UTC: 'UTC',
   }
 
-  // Every X minutes
-  if (cronExpression.match(/^\*\/\d+ \* \* \* \*$/)) {
-    const minutes = cronExpression.split(' ')[0].split('/')[1]
-    return `Every ${minutes} minutes`
-  }
+  return timezoneMap[timezone] || timezone
+}
 
-  // Daily at specific time
-  if (cronExpression.match(/^\d+ \d+ \* \* \*$/)) {
-    const minute = Number.parseInt(parts[0], 10)
-    const hour = Number.parseInt(parts[1], 10)
-    const period = hour >= 12 ? 'PM' : 'AM'
-    const hour12 = hour % 12 || 12
-    return `Daily at ${hour12}:${minute.toString().padStart(2, '0')} ${period}`
-  }
-
-  // Every hour at specific minute
-  if (cronExpression.match(/^\d+ \* \* \* \*$/)) {
-    const minute = parts[0]
-    return `Hourly at ${minute} minutes past the hour`
-  }
-
-  // Specific day of week at specific time
-  if (cronExpression.match(/^\d+ \d+ \* \* \d+$/)) {
-    const minute = Number.parseInt(parts[0], 10)
-    const hour = Number.parseInt(parts[1], 10)
-    const dayOfWeek = Number.parseInt(parts[4], 10)
-    const days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']
-    const day = days[dayOfWeek % 7]
-    const period = hour >= 12 ? 'PM' : 'AM'
-    const hour12 = hour % 12 || 12
-    return `Every ${day} at ${hour12}:${minute.toString().padStart(2, '0')} ${period}`
-  }
-
-  // Specific day of month at specific time
-  if (cronExpression.match(/^\d+ \d+ \d+ \* \*$/)) {
-    const minute = Number.parseInt(parts[0], 10)
-    const hour = Number.parseInt(parts[1], 10)
-    const dayOfMonth = parts[2]
-    const period = hour >= 12 ? 'PM' : 'AM'
-    const hour12 = hour % 12 || 12
-    const day =
-      dayOfMonth === '1'
-        ? '1st'
-        : dayOfMonth === '2'
-          ? '2nd'
-          : dayOfMonth === '3'
-            ? '3rd'
-            : `${dayOfMonth}th`
-    return `Monthly on the ${day} at ${hour12}:${minute.toString().padStart(2, '0')} ${period}`
-  }
-
-  // Weekly at specific time
-  if (cronExpression.match(/^\d+ \d+ \* \* [0-6]$/)) {
-    const minute = Number.parseInt(parts[0], 10)
-    const hour = Number.parseInt(parts[1], 10)
-    const dayOfWeek = Number.parseInt(parts[4], 10)
-    const days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']
-    const day = days[dayOfWeek % 7]
-    const period = hour >= 12 ? 'PM' : 'AM'
-    const hour12 = hour % 12 || 12
-    return `Weekly on ${day} at ${hour12}:${minute.toString().padStart(2, '0')} ${period}`
-  }
-
-  // Return a more detailed breakdown if none of the patterns match
+/**
+ * Converts a cron expression to a human-readable string format
+ * Uses the cronstrue library for accurate parsing of complex cron expressions
+ *
+ * @param cronExpression - The cron expression to parse
+ * @param timezone - Optional IANA timezone string to include in the description
+ * @returns Human-readable description of the schedule
+ */
+export const parseCronToHumanReadable = (cronExpression: string, timezone?: string): string => {
   try {
-    const [minute, hour, dayOfMonth, month, dayOfWeek] = parts
-    let description = 'Runs '
+    // Use cronstrue for reliable cron expression parsing
+    const baseDescription = cronstrue.toString(cronExpression, {
+      use24HourTimeFormat: false, // Use 12-hour format with AM/PM
+      verbose: false, // Keep it concise
+    })
 
-    // Time component
-    if (minute === '*' && hour === '*') {
-      description += 'every minute '
-    } else if (minute.includes('/') && hour === '*') {
-      const interval = minute.split('/')[1]
-      description += `every ${interval} minutes `
-    } else if (minute !== '*' && hour !== '*') {
-      const hourVal = Number.parseInt(hour, 10)
-      const period = hourVal >= 12 ? 'PM' : 'AM'
-      const hour12 = hourVal % 12 || 12
-      description += `at ${hour12}:${minute.padStart(2, '0')} ${period} `
+    // Add timezone information if provided and not UTC
+    if (timezone && timezone !== 'UTC') {
+      const tzAbbr = getTimezoneAbbreviation(timezone)
+      return `${baseDescription} (${tzAbbr})`
     }
 
-    // Day component
-    if (dayOfMonth !== '*' && month !== '*') {
-      const months = [
-        'January',
-        'February',
-        'March',
-        'April',
-        'May',
-        'June',
-        'July',
-        'August',
-        'September',
-        'October',
-        'November',
-        'December',
-      ]
-
-      if (month.includes(',')) {
-        const monthNames = month.split(',').map((m) => months[Number.parseInt(m, 10) - 1])
-        description += `on day ${dayOfMonth} of ${monthNames.join(', ')}`
-      } else if (month.includes('/')) {
-        // Handle interval patterns like */3, 1/3, etc.
-        const interval = month.split('/')[1]
-        description += `on day ${dayOfMonth} every ${interval} months`
-      } else if (month.includes('-')) {
-        // Handle range patterns like 1-6
-        const [start, end] = month.split('-').map((m) => Number.parseInt(m, 10))
-        const startMonth = months[start - 1]
-        const endMonth = months[end - 1]
-        description += `on day ${dayOfMonth} from ${startMonth} to ${endMonth}`
-      } else {
-        // Handle specific month numbers
-        const monthIndex = Number.parseInt(month, 10) - 1
-        const monthName = months[monthIndex]
-        if (monthName) {
-          description += `on day ${dayOfMonth} of ${monthName}`
-        } else {
-          description += `on day ${dayOfMonth} of month ${month}`
-        }
-      }
-    } else if (dayOfWeek !== '*') {
-      const days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']
-      if (dayOfWeek.includes(',')) {
-        const dayNames = dayOfWeek.split(',').map((d) => days[Number.parseInt(d, 10) % 7])
-        description += `on ${dayNames.join(', ')}`
-      } else if (dayOfWeek.includes('-')) {
-        const [start, end] = dayOfWeek.split('-').map((d) => Number.parseInt(d, 10) % 7)
-        description += `from ${days[start]} to ${days[end]}`
-      } else {
-        description += `on ${days[Number.parseInt(dayOfWeek, 10) % 7]}`
-      }
-    }
-
-    return description.trim()
-  } catch (_e) {
-    return `Schedule: ${cronExpression}`
+    return baseDescription
+  } catch (error) {
+    logger.warn('Failed to parse cron expression with cronstrue:', {
+      cronExpression,
+      error: error instanceof Error ? error.message : String(error),
+    })
+    // Fallback to displaying the raw cron expression
+    return `Schedule: ${cronExpression}${timezone && timezone !== 'UTC' ? ` (${getTimezoneAbbreviation(timezone)})` : ''}`
   }
 }
 
@@ -672,7 +507,8 @@ export const getScheduleInfo = (
   cronExpression: string | null,
   nextRunAt: string | null,
   lastRanAt: string | null,
-  scheduleType?: string | null
+  scheduleType?: string | null,
+  timezone?: string | null
 ): {
   scheduleTiming: string
   nextRunFormatted: string | null
@@ -689,7 +525,8 @@ export const getScheduleInfo = (
   let scheduleTiming = 'Unknown schedule'
 
   if (cronExpression) {
-    scheduleTiming = parseCronToHumanReadable(cronExpression)
+    // Pass timezone to parseCronToHumanReadable for accurate display
+    scheduleTiming = parseCronToHumanReadable(cronExpression, timezone || undefined)
   } else if (scheduleType) {
     scheduleTiming = `${scheduleType.charAt(0).toUpperCase() + scheduleType.slice(1)}`
   }
diff --git a/apps/sim/stores/panel/console/store.test.ts b/apps/sim/stores/panel/console/store.test.ts
index 9ccc3cf56..0094e1ce0 100644
--- a/apps/sim/stores/panel/console/store.test.ts
+++ b/apps/sim/stores/panel/console/store.test.ts
@@ -21,6 +21,11 @@ describe('Console Store', () => {
       isOpen: false,
     })
     vi.clearAllMocks()
+    // Clear localStorage mock
+    if (global.localStorage) {
+      vi.mocked(global.localStorage.getItem).mockReturnValue(null)
+      vi.mocked(global.localStorage.setItem).mockClear()
+    }
   })
 
   describe('addConsole', () => {
diff --git a/apps/sim/vitest.setup.ts b/apps/sim/vitest.setup.ts
index a2d1c0d7a..2299bb622 100644
--- a/apps/sim/vitest.setup.ts
+++ b/apps/sim/vitest.setup.ts
@@ -8,6 +8,19 @@ global.fetch = vi.fn(() =>
   })
 ) as any
 
+// Mock localStorage and sessionStorage for Zustand persist middleware
+const storageMock = {
+  getItem: vi.fn(() => null),
+  setItem: vi.fn(),
+  removeItem: vi.fn(),
+  clear: vi.fn(),
+  key: vi.fn(),
+  length: 0,
+}
+
+global.localStorage = storageMock as any
+global.sessionStorage = storageMock as any
+
 // Mock drizzle-orm sql template literal globally for tests
 vi.mock('drizzle-orm', () => ({
   sql: vi.fn((strings, ...values) => ({
diff --git a/bun.lock b/bun.lock
index 196e59be8..f45b06834 100644
--- a/bun.lock
+++ b/bun.lock
@@ -6,6 +6,7 @@
       "dependencies": {
         "@linear/sdk": "40.0.0",
         "@t3-oss/env-nextjs": "0.13.4",
+        "cronstrue": "3.3.0",
         "drizzle-orm": "^0.44.5",
         "mongodb": "6.19.0",
         "postgres": "^3.4.5",
@@ -1643,7 +1644,7 @@
 
     "croner": ["croner@9.1.0", "", {}, "sha512-p9nwwR4qyT5W996vBZhdvBCnMhicY5ytZkR4D1Xj0wuTDEiMnjwR57Q3RXYY/s0EpX6Ay3vgIcfaR+ewGHsi+g=="],
 
-    "cronstrue": ["cronstrue@2.61.0", "", { "bin": { "cronstrue": "bin/cli.js" } }, "sha512-ootN5bvXbIQI9rW94+QsXN5eROtXWwew6NkdGxIRpS/UFWRggL0G5Al7a9GTBFEsuvVhJ2K3CntIIVt7L2ILhA=="],
+    "cronstrue": ["cronstrue@3.3.0", "", { "bin": { "cronstrue": "bin/cli.js" } }, "sha512-iwJytzJph1hosXC09zY8F5ACDJKerr0h3/2mOxg9+5uuFObYlgK0m35uUPk4GCvhHc2abK7NfnR9oMqY0qZFAg=="],
 
     "cross-spawn": ["cross-spawn@7.0.6", "", { "dependencies": { "path-key": "^3.1.0", "shebang-command": "^2.0.0", "which": "^2.0.1" } }, "sha512-uV2QOWP2nWzsy2aMp8aRibhi9dlzF5Hgh5SHaB9OiTGEyDTiJJyx0uy51QXdyWbtAHNua4XJzUKca3OzKUd3vA=="],
 
@@ -3357,6 +3358,8 @@
 
     "@trigger.dev/sdk/chalk": ["chalk@5.6.2", "", {}, "sha512-7NzBL0rN6fMUW+f7A6Io4h40qQlG+xGmtMxfbnH/K7TAtt8JQWVQK+6g0UXKMeVJoyV5EkkNsErQ8pVD3bLHbA=="],
 
+    "@trigger.dev/sdk/cronstrue": ["cronstrue@2.61.0", "", { "bin": { "cronstrue": "bin/cli.js" } }, "sha512-ootN5bvXbIQI9rW94+QsXN5eROtXWwew6NkdGxIRpS/UFWRggL0G5Al7a9GTBFEsuvVhJ2K3CntIIVt7L2ILhA=="],
+
     "@trigger.dev/sdk/uuid": ["uuid@9.0.1", "", { "bin": { "uuid": "dist/bin/uuid" } }, "sha512-b+1eJOlsR9K8HJpow9Ok3fiWOWSIcIzXodvv0rQjVoOVNpWMpxf1wZNpt4y9h10odCNrqnYp1OBzRktckBe3sA=="],
 
     "@types/cors/@types/node": ["@types/node@24.2.1", "", { "dependencies": { "undici-types": "~7.10.0" } }, "sha512-DRh5K+ka5eJic8CjH7td8QpYEV6Zo10gfRkjHCO3weqZHWDtAaSTFtl4+VMqOJ4N5jcuhZ9/l+yy8rVgw7BQeQ=="],
diff --git a/package.json b/package.json
index cedfa906d..58805530c 100644
--- a/package.json
+++ b/package.json
@@ -37,6 +37,7 @@
   "dependencies": {
     "@linear/sdk": "40.0.0",
     "@t3-oss/env-nextjs": "0.13.4",
+    "cronstrue": "3.3.0",
     "drizzle-orm": "^0.44.5",
     "mongodb": "6.19.0",
     "postgres": "^3.4.5",