Define ReportingPeriod domain model and boundary types
epic-bufdir-data-aggregation-core-logic-task-001 — Create the ReportingPeriod domain model with start/end date boundaries, period type enum (monthly, quarterly, annual, custom), and immutable value object semantics. Define interfaces for period boundary filtering used throughout the aggregation pipeline.
Acceptance Criteria
Technical Requirements
Implementation Notes
Model this as a pure Dart value object in a dedicated lib/domain/reporting_period/ directory to keep domain logic separate from infrastructure (Supabase) and UI layers. Use Dart's @immutable annotation and make all fields final. Derive the id as '${type.name}-${startDate.toIso8601String()}' to produce a deterministic, human-readable identifier useful for Supabase row keys. For PeriodBoundaryFilter, prefer a functional interface (typedef + extension method) over an abstract class to keep it lightweight and composable.
Norwegian grant reporting cycles follow calendar boundaries: monthly = first to last day of month, quarterly = Jan-Mar/Apr-Jun/Jul-Sep/Oct-Dec, annual = Jan 1 to Dec 31 — bake these as named constructors (ReportingPeriod.monthly(year, month), etc.) to prevent off-by-one errors downstream.
Testing Requirements
Pure Dart unit tests (no Flutter widgets, no Supabase). One test file per public class. Test cases must cover: valid construction for each PeriodType, invalid construction (reversed dates, equal dates), equality and hash consistency, contains() with date on boundary (startDate inclusive, endDate exclusive), contains() with date outside period, overlaps() for adjacent/overlapping/non-overlapping/identical periods, and PeriodBoundaryFilter with an empty list, a list where all items fall inside the period, and a list where some items fall outside. Run with `flutter test` in the package root.
NHF members can belong to up to 5 local chapters. When a participant has activities registered under different chapter IDs within the same reporting period, deduplication requires a reliable cross-chapter identity key. If national IDs are absent for some members (a known data quality issue in NHF's systems), the deduplication service may fail to identify duplicates, resulting in inflated counts submitted to Bufdir.
Mitigation & Contingency
Mitigation: Implement a multi-attribute identity matching strategy: primary match on national_id, fallback to (full_name + birth_year + municipality) composite key. Expose a low-confidence match list in DeduplicationAnomalyReport that coordinators can review and manually resolve before submission.
Contingency: If identity data quality is too poor for reliable automated deduplication for specific organisations, add an organisation-level config flag that disables cross-chapter deduplication for that org and requires coordinators to manually review the anomaly report before submitting.
The geographic distribution algorithm must resolve NHF's 1,400 local chapter hierarchy to regional aggregates. If the organizational unit hierarchy in the database is incomplete (missing parent-child relationships for some chapters), the geographic service will silently drop activities from unmapped chapters, producing an understated geographic breakdown.
Mitigation & Contingency
Mitigation: Add a hierarchy completeness validation step in GeographicDistributionService that counts activities without a resolvable region assignment and surfaces them as an 'unmapped_activities' field in the distribution result. Block export if unmapped_activities > 0.
Contingency: Provide a 'national' fallback bucket for activities from chapters with no region assignment, clearly labelled in the preview screen so coordinators are alerted to fix the org hierarchy data before re-running aggregation.
BufdirAggregationService orchestrates four dependent services. If one service (e.g., GeographicDistributionService) throws mid-pipeline, the partially assembled metrics payload may be silently cached or returned as if complete, resulting in a Bufdir submission missing the geographic breakdown section.
Mitigation & Contingency
Mitigation: Implement the orchestrator as a transactional pipeline using Dart's Result type pattern: each stage returns Either<AggregationError, PartialResult>, and the orchestrator only proceeds if all stages succeed. The final payload is only assembled and persisted when all stages return success.
Contingency: If a partial failure state reaches the UI, the AggregationProgressIndicator must display a specific stage failure message with a retry option that re-runs only the failed stage rather than the full pipeline.
Internal activity types that have no corresponding Bufdir category in the mapping configuration will cause the aggregation to silently exclude those activities from the final counts. Coordinators may not notice the omission until Bufdir queries why submission totals are lower than expected.
Mitigation & Contingency
Mitigation: BufdirAggregationService must produce an unmapped_activity_types list as part of its output. If any internal activity types are unmapped, display a blocking warning in the AggregationSummaryWidget listing the unmapped types before allowing the coordinator to proceed to export.
Contingency: Allow coordinators to temporarily assign unmapped activity types to a Bufdir 'other' catch-all category as an emergency workaround, with an audit flag indicating manual override was applied for that submission.