Implement NavigateSlide event handler in BLoC
epic-annual-impact-summary-orchestration-task-004 — Implement the NavigateSlide event handler to manage current slide index within WrappedSummaryLoaded state. The handler must enforce boundary conditions (first/last slide), update slide position in emitted state, and record slide-view analytics events. Slide count is derived from the loaded summary payload.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 2 - 518 tasks
Can start after Tier 1 completes
Implementation Notes
Since all logic is synchronous, use the standard `on
min(current + 1, slides.length - 1) : max(current - 1, 0)`. Skip emission if `newIndex == currentIndex` (boundary hit). Fire analytics with `unawaited(_analyticsService.recordSlideView(...))` so failures are silently absorbed. If using Dart sealed classes, the `state is!
WrappedSummaryLoaded` guard will be enforced by the compiler when pattern matching — prefer that approach.
Testing Requirements
Unit tests with bloc_test. Test cases: (1) next navigation from middle index increments index by 1, (2) previous navigation from middle index decrements by 1, (3) next from last index emits no state change, (4) previous from index 0 emits no state change, (5) event ignored when state is WrappedSummaryLoading, (6) analytics service receives correct slideIndex and period on valid navigation, (7) analytics service failure does not emit error state. Verify that non-index fields (slides, milestones, period) are identical between input and output states using Equatable.
If the device transitions between online and offline states while the user is mid-session in the wrapped screen, the BLoC may emit conflicting state transitions (loaded → error → offline) that cause visual flickering or an inconsistent UI state such as showing the offline banner over an already-loaded summary.
Mitigation & Contingency
Mitigation: Implement a connectivity stream listener in the BLoC that only triggers a state re-evaluation when transitioning from online to offline, not on every connectivity event. Once a summary is in the Loaded state, the BLoC should not transition to error/offline unless the user explicitly requests a refresh. Store the last-loaded data in BLoC state so it survives connectivity changes.
Contingency: If state flickering is observed in testing, add a minimum 3-second debounce on connectivity state changes before the BLoC reacts, and display a non-blocking top banner rather than replacing the entire screen state.
The push notification deep-link to the wrapped-summary-screen must work correctly whether the app is in the foreground, background, or terminated state. Handling all three app launch states on both iOS and Android is a common source of edge-case bugs, particularly when authentication state must be restored before the deep link can be resolved.
Mitigation & Contingency
Mitigation: Implement deep-link handling through the existing notification-deep-link-handler component which already manages app-state-aware routing. Define the wrapped-summary route in the navigation config early in the epic so the router is ready before notification dispatch is wired. Test all three app states (foreground, background, terminated) explicitly in the QA checklist.
Contingency: If terminated-state deep-linking fails on specific platforms, fall back to launching the app to the home screen with an in-app notification banner prompting the user to open their summary, rather than direct deep-link navigation.
The wrapped-summary-screen manages a large number of AnimationController instances (one or more per slide) via the wrapped-animation-controller. If disposal is not triggered correctly when the user exits mid-flow (e.g., via system back gesture or deep-link away), memory leaks will accumulate across session navigation.
Mitigation & Contingency
Mitigation: Implement screen disposal via Flutter's dispose() lifecycle method calling a single wrapped-animation-controller.disposeAll() method that iterates the named controller registry. Write a test that navigates to the screen, starts animations, then navigates away and verifies no active AnimationController listeners remain using Flutter's test binding.
Contingency: If disposal bugs are detected in production via memory profiling, patch by converting all AnimationControllers to use AutomaticKeepAliveClientMixin false and wrap each slide in a widget that disposes its own controller when removed from the widget tree.