Real Decision
Why calendar sync became its own domain with separate ownership and integration rules.
Problem
Calendar synchronization involves external providers, token handling, sync conflicts and retry strategies that do not belong inside core business applications.
Decision
Calendar synchronization was isolated into its own service boundary so provider-specific behavior, sync logic and background reconciliation could be owned and evolved independently.
Why Not
Scatter provider integrations across multiple services.
Mix calendar conflict resolution into normal request-response flows.