ReceiptStorageRepository upload and signed URL methods
epic-receipt-capture-and-attachment-foundation-task-005 — Implement the ReceiptStorageRepository class with methods for uploading a compressed image Uint8List to the Supabase Storage path, generating a short-lived signed URL for displaying a receipt image, and deleting a receipt file by its storage path. Inject the Supabase client via Riverpod. Handle network errors with typed exceptions.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 1 - 540 tasks
Can start after Tier 0 completes
Implementation Notes
The supabase_flutter SDK's storage client exposes supabase.storage.from('receipts').uploadBinary(path, bytes, fileOptions: FileOptions(contentType: mimeType, upsert: false)). Set upsert: false to prevent silent overwrites — callers should always use unique filenames (UUID-based). For progress reporting, use the onUploadProgress callback in FileOptions. Map StorageException.statusCode to StorageErrorType in a private _mapException() helper to keep the catch block clean.
For getSignedUrl, use supabase.storage.from('receipts').createSignedUrl(path, expiresIn) where expiresIn is in seconds. Wrap all three SDK calls in try/catch StorageException and re-throw as ReceiptStorageException. Do not catch generic Exception — let unexpected errors propagate so they surface in crash reporting.
Testing Requirements
Unit tests using a mock IReceiptStorageRepository (via mockito or mocktail) to test callers. For the repository implementation itself, write integration tests (covered in task-015) against a real Supabase test bucket. At minimum, add one unit test per public method that verifies the typed exception is thrown when the underlying Supabase SDK throws a StorageException — use a mock SupabaseClient for this. Assert that ReceiptStorageException.type is correctly mapped from Supabase's HTTP status codes: 403 → unauthorized, 413 → quotaExceeded, network timeout → networkError.
Supabase Storage RLS policies using org/user/claim path scoping may not enforce correctly if claim ownership is not present in the JWT or if path segments are constructed differently at upload vs. read time, leading to data leakage or access denial for legitimate users.
Mitigation & Contingency
Mitigation: Define and test RLS policies in isolation before wiring to app code. Write integration tests that assert cross-org and cross-user access is denied. Use service-role key only in edge functions, never in client code.
Contingency: If client-side RLS proves insufficient, route all storage reads through a Supabase Edge Function that validates ownership before generating signed URLs, adding a controlled server-side enforcement layer.
Aggressive image compression may reduce receipt legibility below the threshold required for financial auditing, causing claim rejections or compliance failures despite technically successful uploads.
Mitigation & Contingency
Mitigation: Define minimum legibility requirements with HLF finance team before implementation. Set compression targets conservatively (e.g., max 1MB, min 80% JPEG quality) and validate with sample receipt images. Provide compression statistics in verbose/debug mode.
Contingency: If post-compression quality is disputed by auditors, increase the quality floor at the cost of larger file sizes, and add a manual override allowing users to skip compression for PDFs and high-quality scans.
The Flutter image_picker package behaves differently on iOS 17+ (PHPicker) vs older Android (Intent-based), particularly for file types, permission flows, and PDF selection, which may cause platform-specific failures not caught in development.
Mitigation & Contingency
Mitigation: Test image picker integration on physical devices for both platforms early in the sprint. Pin the image_picker package version and review changelogs before updates. Write widget tests using mock file results for each platform branch.
Contingency: If PHPicker or Android Intent differences cause blocking issues, implement separate platform-specific picker delegates behind the unified interface, allowing platform-specific fixes without breaking the shared API.