Organization Persistence Repository

This is a low-complexity data layer component with a single dependency on the local storage adapter, making it one of the earliest deliverables in the mobile data layer. A junior-to-mid developer can implement and test it within two to three days. It is a foundational dependency for the Organization Selection Service, so it must be completed and verified before service-layer integration work begins — plan it early in the sprint to avoid blocking downstream tasks. Testing should cover save, load, and clear operations including null/empty state handling and behavior on first install when no value is stored.

No network or backend dependencies reduce deployment risk to near zero.

A thin repository wrapping Flutter's `SharedPreferences` plugin, this component exposes three async operations: `saveSelectedOrgId(String orgId)`, `loadSelectedOrgId()` returning `Future`, and `clearSelectedOrgId()`. It depends on a `local-storage-adapter` abstraction, which should be injected via constructor for testability — allowing unit tests to mock storage without hitting the file system. The nullable return type on `loadSelectedOrgId()` is intentional and must be handled by callers (typically the Organization Selection Service) to distinguish first-run from previously persisted state. Keep this class strictly focused on storage I/O; business logic such as validation or fallback organization selection belongs in the service layer above it.