Implement ActivityRegistrationCubit initialization with defaults
epic-quick-activity-registration-business-logic-task-008 — Implement the Cubit constructor and initializeWithDefaults() async method that calls RegistrationDefaultsManager.getDefaults() and emits an initial ActivityRegistrationStep state with all fields pre-populated. This is the critical path for the zero-input happy path — the UI must be ready to submit immediately after the sheet opens without the user changing any field.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 2 - 518 tasks
Can start after Tier 1 completes
Implementation Notes
Use the BLoC library's Cubit base class (not Bloc — no events needed here, only method calls). Inject dependencies via constructor to enable easy mocking in tests. The RegistrationDefaultsManager should be a Riverpod provider so it can share cached state across the app — the Cubit reads it via its injected interface, not directly from Riverpod. Do not use emit() after the cubit is closed — guard all async emit calls with `if (!isClosed) emit(...)`.
The date default must be DateTime.now() evaluated at the time initializeWithDefaults() is called, not at construction time. Document that this method must be called from the widget's initState or equivalent — not from the constructor.
Testing Requirements
Unit tests with flutter_test and bloc_test package. Use bloc_test's blocTest() helper to test state emission sequences. Tests: (1) initial state is ActivityRegistrationInitial, (2) after initializeWithDefaults() with valid mocked defaults, states are [ActivityRegistrationInitial, ActivityRegistrationStep(date: today, durationMinutes: 30, ...)], (3) after initializeWithDefaults() with RegistrationDefaultsManager throwing, states are [ActivityRegistrationInitial, ActivityRegistrationFailure(...)], (4) calling initializeWithDefaults() twice re-emits ActivityRegistrationStep — no stuck state, (5) verify RegistrationDefaultsManager.getDefaults() is called exactly once per initializeWithDefaults() invocation.
The wizard Cubit manages multiple concurrent state slices (current step, each field value, submission status, error state). As the number of wizard steps grows, the state class can become unwieldy, making it difficult to reason about transitions, leading to subtle bugs where advancing a step resets a previously filled field.
Mitigation & Contingency
Mitigation: Use an immutable state model (copyWith pattern) with a separate sealed class per wizard step state. Keep the Cubit's emit calls minimal and always derive the next state from the current state to prevent accidental field resets. Document the state machine transitions explicitly in code comments.
Contingency: If state complexity becomes unmanageable, split into a parent WizardCubit (owns step navigation and submission) and per-step child Cubits (own individual field state), coordinating via a shared repository layer.
Organisation-specific compensation eligibility rules (e.g., activity type + duration thresholds) are business logic that may change independently of the app release cycle. Hardcoding these rules in ActivityRegistrationService means rule changes require a new app deployment, causing delays and potential financial errors if the deployed version uses outdated rules.
Mitigation & Contingency
Mitigation: Model compensation rules as configuration fetched from Supabase (stored per organisation), cached locally. ActivityRegistrationService reads from cache with a fallback to hardcoded defaults for offline scenarios. Design the rule schema to be extensible without code changes.
Contingency: If dynamic rules are not ready for initial release, ship with hardcoded rules and a feature flag that enables the remote-config path. Document the rule structure clearly so coordinators can trigger a rule update via a Supabase dashboard entry rather than a code deployment.
The last-used activity type stored in RegistrationPreferencesStore may become invalid if the organisation administrator deactivates that activity type between sessions. The Cubit would pre-populate a deleted type, and either the UI would show a missing item or submission would fail with a foreign-key constraint error.
Mitigation & Contingency
Mitigation: In RegistrationDefaultsManager, validate the retrieved last-used activity type ID against the current list of active types fetched from the activity type repository. If the stored ID is not in the active list, fall back to the first active type alphabetically.
Contingency: If validation cannot be performed offline, surface a non-blocking warning in the activity type step ('Your previously used activity type is no longer available') and require the user to make a new selection before advancing.