#### PR Dependency Tree
* **PR #14510** 👈
This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)
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## Summary by CodeRabbit
* **Bug Fixes**
* Improved calendar sync reliability with exponential backoff for
repeated failures.
* Better handling of token refresh failures with automatic account
invalidation and cleanup when needed.
* Subscriptions are now automatically disabled and related events
removed when the calendar provider reports missing resources.
* **Tests**
* Added comprehensive tests covering sync failures, backoff behavior,
token refresh handling, skipping retries during backoff, and recovery.
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