Proxy Contact List Provider

This is a low-complexity Riverpod provider with no external service dependencies, making it one of the lower-risk components in the proxy registration feature set. Development effort is primarily in implementing correct cache invalidation logic — ensuring the contact list refreshes when underlying data changes without triggering unnecessary re-fetches. Because it is marked as shared and consumed by at least three screens (proxy mode selector, single-selector, multi-select), any behavioral change or bug fix will have a broader blast radius and requires regression testing across all consuming screens. No backend or database migrations are needed.

The main delivery risk is ensuring cache invalidation timing aligns with the lifecycle of each screen, which requires close coordination with UI developers working on the consuming widgets.

ProxyContactListProvider is a Riverpod provider (likely AsyncNotifierProvider or StreamProvider) that wraps the coordinator's peer mentor contact list and exposes it as reactive state to multiple UI layers. watchCoordinatorMentors(coordinatorId) sets up the primary stream or future, while searchMentors(query) performs client-side filtering over the cached list to avoid redundant API calls during search interactions. refreshContacts() manually invalidates the provider's cache, triggering a fresh fetch — important for pull-to-refresh patterns. getMentorById(mentorId) provides O(1) lookup from the cached list for detail retrieval without a network round-trip.

The component operates exclusively in the mobile execution context. Because it is shared across multiple screens within the same session, the provider's ref.keepAlive() or autoDispose behavior must be carefully configured to balance memory usage against re-fetch cost. No dependencies on other components are declared, implying direct Supabase client or repository access at the provider level.