Implement per-branch expand and collapse in HierarchyTreeView
epic-organizational-hierarchy-management-core-services-task-017 — Add independent expand/collapse state per tree branch to HierarchyTreeView using an AnimatedContainer or ExpansionTile equivalent. Each node remembers its expanded state locally. Provide expand-all and collapse-all controls at the tree root. Animate transitions for smooth UX compliant with WCAG 2.2 AA reduced-motion requirements.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 6 - 158 tasks
Can start after Tier 5 completes
Implementation Notes
Store expanded state in HierarchyNodeTile as a bool _isExpanded in local State<>. For expand-all/collapse-all, lift state management using a ValueNotifier
Check MediaQuery.of(context).disableAnimations at build time and set duration to Duration.zero if true — this is the WCAG 2.2 AA reduced motion compliance pattern in Flutter. Do not use ExpansionTile from Flutter's material library unless you can fully override its animation — it has opinionated sizing and header padding that conflicts with the design token system.
Testing Requirements
Widget tests (flutter_test): mount a 3-level tree; tap chevron on root node and assert children are hidden; tap again and assert children are visible. Test that expand-all makes all nodes' children visible. Test that collapse-all hides all children. Test that expanding node A and collapsing node B does not affect node A's state.
Accessibility test: set MediaQuery.disableAnimations = true in test scope and assert no AnimationController is running after toggle. Verify chevron tap target is at least 44×44dp using a Size assertion.
Injecting all unit assignment IDs into JWT claims for users assigned to many units (up to 5 for NHF peer mentors, many more for national coordinators) may exceed JWT size limits, causing authentication failures.
Mitigation & Contingency
Mitigation: Store unit IDs in a Supabase session variable or a dedicated Postgres function rather than embedding them directly in the JWT payload. Use set_config('app.unit_ids', ...) within RLS helper functions querying the assignments table at policy evaluation time.
Contingency: Fall back to querying the unit_assignments table directly within RLS policies using the authenticated user ID, accepting a small per-query overhead in exchange for removing the JWT size constraint.
Rendering 1,400+ nodes in a recursive Flutter tree widget may cause jank or memory pressure on lower-end devices used by field peer mentors, degrading the admin experience.
Mitigation & Contingency
Mitigation: Implement lazy tree expansion — only the root level is rendered on initial load. Child nodes are rendered on demand when the parent is expanded. Use const constructors and ListView.builder for all node lists to minimize rebuild scope.
Contingency: Add a search/filter bar that scopes the visible tree to matching nodes, reducing the visible node count. Provide a 'flat list' fallback view for administrators who prefer searching over browsing the tree.
Requirements for what constitutes a valid hierarchy structure may expand during NHF sign-off (e.g., mandatory coordinator assignments per chapter, minimum member counts per region), requiring repeated validator redesign.
Mitigation & Contingency
Mitigation: Design the validator as a pluggable rule engine where each check is a discrete, independently testable function. New rules can be added without changing the core validation orchestration. Surface all rules in a configuration table per organization.
Contingency: Defer non-blocking validation rules to warning-level feedback rather than hard blocks, allowing structural changes to proceed while flagging potential issues for admin review.
Deploying RLS policy migrations to a shared Supabase project used by multiple organizations simultaneously could lock tables or interrupt active sessions, causing downtime during production migration.
Mitigation & Contingency
Mitigation: Write all RLS policies as CREATE POLICY IF NOT EXISTS statements. Schedule migrations during off-peak hours. Use Supabase's migration preview environment to validate policies against production data shapes before applying.
Contingency: Prepare rollback migration scripts for every RLS policy. If a migration causes issues, execute the rollback immediately and re-test the policy logic in staging before reattempting.