Implement ReceiptThresholdValidator service
epic-receipt-capture-and-attachment-core-logic-task-004 — Create the ReceiptThresholdValidator service that evaluates whether an expense claim amount exceeds the 100 kr threshold requiring a receipt attachment. Implement isReceiptRequired(amount) and getThresholdConfig() methods reading from org-specific configuration. This validator drives the mandatory attachment UI state in the expense wizard.
Acceptance Criteria
Technical Requirements
Implementation Notes
Represent monetary amounts as double or, preferably, as an integer number of øre (smallest currency unit) to avoid floating-point comparison bugs. If using doubles, use a small epsilon only at the display layer — comparisons in this service should be exact. The threshold value (100 kr) originates from the HLF workshop requirement: 'Kvitteringsbilde for utlegg over 100 kr'. Store this as a named constant (kDefaultReceiptThresholdNOK = 100.0) and document its business origin.
Load org config via a Riverpod provider that reads from Supabase's org_settings table or a locally cached version. This service will be read on every keystroke in the amount field — keep it O(1) and allocation-free.
Testing Requirements
Unit tests (flutter_test): cover isReceiptRequired with amounts of 0, 50, 99.99, 100.00, 100.01, and 500. Cover getThresholdConfig with a mock config source returning an org-specific override and with a missing/null config to verify fallback. All tests must be synchronous where the method is synchronous. Target 100% branch coverage for this service given its small surface area.
Non-blocking upload creates a race condition: if the claim record is submitted and saved before the upload completes, the storage path may never be written to the claim_receipts table, leaving the claim with a missing receipt that was nonetheless required.
Mitigation & Contingency
Mitigation: Design the attachment service to queue a completion callback that writes the storage path to the claim record upon upload completion, even after the claim form has submitted. Use a local task queue with persistence to survive app backgrounding. Test the race condition explicitly with simulated slow uploads.
Contingency: If the async path association proves unreliable, fall back to blocking upload before claim submission with a clear progress indicator, accepting the UX trade-off in exchange for data integrity.
The offline capture requirement (cache locally, sync when connected) significantly increases state management complexity. If the offline queue is not durable, receipts captured without connectivity may be lost when the app is killed, causing claim submission failures users are not aware of.
Mitigation & Contingency
Mitigation: Persist the offline upload queue to local storage (e.g., Hive or SQLite) on every state transition. Implement background sync using WorkManager (Android) and BGTaskScheduler (iOS). Scope the initial delivery to online-only flow if offline sync cannot be adequately tested before release.
Contingency: Ship without offline support in the first release, displaying a clear 'Upload requires connection' message. Add offline sync as a follow-on task once the core online flow is validated in production.
The inline bottom sheet presentation within a multi-step wizard can conflict with existing modal navigation and back-button handling, particularly if the expense wizard itself uses nested navigation or custom route management.
Mitigation & Contingency
Mitigation: Review the expense wizard navigation architecture before implementation. Use showModalBottomSheet with barrier dismissal disabled to prevent accidental dismissal. Coordinate with the expense wizard team on modal stacking behavior and ensure the camera sheet does not interfere with wizard step transitions.
Contingency: If modal stacking causes navigation issues, present the camera sheet as a full-screen dialog using PageRouteBuilder with a transparent barrier, preserving wizard state via the existing Bloc while still appearing inline.