Phase 2: Bidirectional Google Calendar sync

[akhilk999]

Summary

Follow-up to app → CSA Member Calendar sync (v1). Add calendar → app updates so schedule/location edits on the shared CSA Member Calendar update the corresponding points event.

Background

v1 already pushes eligible org events (create/update/delete) to the Member Calendar via a service account and stores google_event_id on events. Mixers, Jiating Events, and Sports Spectator children are excluded.

Proposed approach

1. Use Google Calendar push notifications (events.watch) to a Next.js webhook (e.g. /api/google-calendar/webhook) with channel renewal, or periodic events.list with syncToken.
2. Match Calendar events to app rows via google_event_id.
3. Update only fields the app allows today: starts_at / ends_at / location (and maybe description / RSVP metadata).
4. Conflict handling: last-write-wins with timestamps, or treat the app as authoritative for points metadata and Calendar as authoritative only for schedule/location.
5. Ignore Spectator / non-mapped Calendar edits; do not auto-create points events from arbitrary Calendar creates unless an explicit mapping rule is added later.

Out of scope (unless revisited)

• Per-member personal calendar sync
• Expanding member Google OAuth scopes
• Editing event name/category from Calendar
• Auto-import of manually created Google events into the points app

Acceptance criteria

• Edits to synced events on the CSA Member Calendar update matching app events (schedule/location at minimum)
• Non-mapped / ineligible Calendar changes do not create or corrupt points events
• Channel renewal or sync-token polling is reliable in production
• Conflict behavior is documented and deterministic