Implement proxy wizard BLoC state management
epic-bulk-and-proxy-registration-bulk-ui-task-004 — Build the ProxyActivityWizardCubit/BLoC that carries the selected peer_mentor_id and recorded_by_user_id through all wizard steps, manages step transitions in proxy mode, and assembles the final ProxyActivityPayload on submission. State must surface the attribution data to the banner widget via Riverpod or BLoC context.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 3 - 413 tasks
Can start after Tier 2 completes
Implementation Notes
Use Cubit rather than full BLoC (no event classes needed) since state transitions are straightforward method calls. Define `ProxyActivityWizardState` as an immutable class with: currentStepIndex, peerMentorId, peerMentorFullName, recordedByUserId, activityType, date, duration, notes, status (enum: initial/loading/success/error), errorMessage. Implement `copyWith` for all fields. For step index management, compute the valid step list once in the Cubit constructor based on isProxyMode and store it as a final List — use the list length for boundary checks rather than hardcoded step counts.
For Riverpod integration, expose the Cubit via a `StateNotifierProvider` or `Provider` scoped to the wizard route. Ensure the repository abstraction (interface + Supabase implementation) is injected via constructor for testability.
Testing Requirements
Use bloc_test's `blocTest` function for all Cubit tests. Cover: (1) emits correct initial state with provided peer_mentor_id and recorded_by_user_id, (2) nextStep increments step index and skips peer mentor step, (3) previousStep decrements step index correctly, (4) submit with a mock Supabase repository emits loading then success state, (5) submit with a repository that throws emits loading then error state with non-empty message, (6) state equality — two states with identical fields are equal. Mock the Supabase repository using Mockito or a hand-written fake. No widget tests required in this task — those are covered in tasks 002 and 003.
If the batch insert RPC returns a mix of successes and failures (e.g., 3 of 10 mentors fail due to constraint violations that slipped through application-level duplicate detection), the confirmation screen result state becomes ambiguous. A coordinator who sees '7 of 10 succeeded' may not know whether to manually register the 3 failures, retry, or escalate — leading to either duplicate registrations or silent underreporting.
Mitigation & Contingency
Mitigation: Design the Bulk Registration Service to return a strongly typed BulkRegistrationResult with per-mentor RegistrationOutcome (success | duplicate_detected | constraint_violation | permission_denied). Design the result screen to list each failed mentor with a specific, plain-language reason and a one-tap 'Retry for this mentor' action that pre-fills the activity wizard with the batch template for that individual.
Contingency: If per-mentor retry UI is too complex to deliver within the epic scope, fall back to displaying failed mentors with their error codes and instructing coordinators to use single-proxy mode for the failures. Document this as a known limitation in release notes and create a follow-up ticket for per-mentor retry in the next sprint.
The Proxy Activity Wizard must reuse the existing activity wizard step widgets (type, date, duration, notes) while injecting a proxy attribution banner and a different submission payload builder. If the existing wizard is not designed for composability, the proxy variant may require forking the widget tree, creating two maintenance-diverging codebases that will drift out of sync when the base wizard is updated (e.g., new activity types added, new mandatory fields).
Mitigation & Contingency
Mitigation: Before implementing the Proxy Activity Wizard, audit the existing activity wizard's architecture. If steps are already extracted as independent StatelessWidget/ConsumerWidget classes, compose them directly with a wrapping Column that injects the attribution banner. If they are tightly coupled inside a parent widget, refactor the existing wizard to accept a nullable ProxyContext parameter before starting the proxy variant — this refactor should be a prerequisite task in this epic.
Contingency: If refactoring the base wizard is blocked by unrelated in-flight work on that component, implement the proxy wizard as a full fork but create a shared StepWidgets library file that both the base wizard and proxy wizard import. Schedule a deduplication refactor as a tech-debt ticket in the next planning cycle.
The bulk registration flow spans three sequential screens (multi-select → activity form → confirmation → result) with shared mutable state: the selected mentor list, the activity template, the per-mentor duplicate warnings, and the final submission result. Managing this state across screens without a well-designed Bloc risks state leaks, stale duplicate warning data after mentor removal, and confirmation screen inconsistencies if the user navigates back and changes the mentor selection.
Mitigation & Contingency
Mitigation: Define a single BulkRegistrationBloc (or Cubit) with explicit state transitions covering: MentorsSelected → ActivityTemplateCompleted → DuplicatesChecked → ConfirmationReady → Submitting → SubmissionResult. Each backward navigation event (e.g., 'Back' from confirmation to mentor selection) dispatches a ResetToMentorSelection event that clears downstream state. Unit test every state transition with edge cases including empty mentor list, all mentors having duplicates, and network failure during submission.
Contingency: If state management complexity causes persistent bugs in testing, simplify by passing state explicitly through Navigator arguments (immutable snapshots per screen) rather than a shared Bloc. This reduces flexibility but eliminates cross-screen state mutation bugs.