# System Calendar Sync

System Calendar Sync writes selected birthdays into the Apple Calendar app. It is useful when you want birthdays to appear beside the rest of your schedule, outside Cakeday.

Calendar Sync does not replace Cakeday notifications. It adds calendar events. Keep app notifications on if you still want Cakeday reminder behavior.

## What Cakeday Creates

Cakeday creates and manages a calendar named **Cakeday**. For each friend with **Sync to System Calendar** enabled, it writes all-day birthday events for the current projection window and keeps those events updated when the friend changes.

The event title, notes, date, zodiac details, group name, and Cakeday deep link are managed by the app.

## Permission

Calendar Sync requires full Calendar access. If access is denied, Cakeday cannot create, update, or remove the managed events.

Open **Cakeday > Settings > Calendar Settings** to check permission and request access.

## Per-Friend Calendar Sync

Open a friend, tap **Edit**, then turn on **Sync to System Calendar** in the **Calendar** section.

This per-friend switch is helpful when you want only important birthdays in Apple Calendar while keeping all birthday records in Cakeday.

## Calendar Settings

The Calendar Settings page includes:

- **Auto Sync:** Updates managed calendar events when birthdays are added, edited, or deleted.
- **Sync Now:** Manually rebuilds and updates managed events.
- **Retry Failed:** Re-attempts any birthday events that failed during the last sync.
- **Clean Up Extra Calendar:** Removes an older extra Cakeday calendar while keeping current events and app data.
- **Remove All Events:** Removes the Cakeday calendar and its events from Apple Calendar. This does not delete birthday data from Cakeday.

## iCloud and Calendar Location

When iCloud Sync is enabled in Cakeday, the managed calendar can use an iCloud-backed calendar source when available. This helps the Calendar app show events across devices signed into the same Apple ID.

Calendar availability still depends on Apple's Calendar and iCloud settings on each device.

## Lunar Birthdays

For lunar birthdays, Cakeday calculates the matching solar dates for the projection window and writes those all-day events into the system calendar. If a lunar date cannot be resolved for a year, that year's event is skipped rather than guessed.

## Troubleshooting

**Calendar events do not appear**

Check **Settings > Privacy & Security > Calendars** and make sure Cakeday has full access. Then open **Calendar Settings** and use **Sync Now**.

**I see an extra Cakeday calendar**

Use **Clean Up Extra Calendar** when it appears. It removes an older managed calendar without deleting your birthday records.

**I want to remove calendar events only**

Use **Remove All Events** in Calendar Settings. It removes the Cakeday calendar from Apple Calendar but keeps your birthdays inside Cakeday.