https://android.googlesource.com/platform/packages/apps/Calendar/+/84849aca7813b0c746d37ccbbaced820a838e3b1/extensions_src/com/android/calendar/extensions
extensions_src/com/android/calendar/extensions - platform/packages/apps/Calendar - Git at Google
android calendarplatform packagesextensionssrc
https://www.groupcal.app/
GroupCal - Calendar Platform Built for Sharing Schedules
Mar 29, 2026 - A robust platform for real-time calendar sync and seamless coordination across groups, teams, communities, and audiences.
calendar platformbuiltsharingschedules