Implement final metrics payload assembly and audit metadata
epic-bufdir-data-aggregation-core-logic-task-015 — Implement the final output stage of BufdirAggregationService: assembleMetricsPayload(period, orgId) that structures deduplicated counts, geographic breakdowns, and category totals into the Bufdir submission schema. Attach audit metadata: deduplication counts removed, data sources, pipeline timestamps, and version for legal compliance traceability.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 7 - 84 tasks
Can start after Tier 6 completes
Implementation Notes
Define BufdirSubmissionPayload as a freezed data class with toJson() generated by json_serializable. The Bufdir schema should be documented in a const or loaded from an asset file for validation purposes. For audit metadata, define a separate AuditMetadata freezed class containing all traceability fields. Persist audit log using Supabase upsert on a composite unique key (org_id + reporting_period_id + pipeline_version) to ensure idempotency.
Use Dart's DateTime.now().toUtc().toIso8601String() for all timestamps in audit metadata to ensure consistent timezone handling for legal compliance. Define PIPELINE_SCHEMA_VERSION = '1.0.0' as a top-level constant and reference it everywhere. For the ValidationFailureResult pattern, use a sealed class Result
Testing Requirements
Unit tests: assert that assembleMetricsPayload correctly maps deduplicated counts, geographic breakdowns, and category totals into BufdirSubmissionPayload fields. Test toJson() output matches expected JSON structure (snapshot test). Test that audit metadata contains correct deduplication delta (raw - deduped). Test ValidationFailureResult is returned when a required Bufdir schema field is missing.
Test idempotency: call twice, assert audit log has exactly 1 entry (upsert behavior). Integration test: run full pipeline and assert assembled payload JSON passes a Bufdir JSON schema validator (use a Dart JSON schema validation library or manual field-level assertions). Use flutter_test.
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.