Paste your OAuth Client ID (Google Cloud → Credentials). It is safe in the page — no secret is used.
Holiday calendars to show
Connect to load your subscribed holiday calendars.
Planner and Calendar now sync automatically in the background — new activities push to Calendar a few seconds after you stop typing, and new Calendar events pull into today's Planned list whenever you add an activity (or tap "sync from calendar"). To-do tasks stay local. The buttons below are for manual/first-time use — Connect once per Google session; after that it reconnects quietly on its own.