Implement signed URL generation for declarations
epic-driver-and-confidentiality-management-core-services-task-004 — Extend the declaration storage adapter to generate short-lived signed URLs for authenticated drivers to download their encrypted declaration file. Signed URLs must expire after a configurable TTL (default 24 hours), be scoped to the specific file path, and log each URL generation event for audit purposes.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 3 - 413 tasks
Can start after Tier 2 completes
Implementation Notes
Use supabaseAdmin.storage.from('declarations').createSignedUrl(objectPath, ttlSeconds) from the Supabase Storage JS SDK inside the Edge Function. Parse and validate the requesting user's JWT via supabase.auth.getUser() — extract the org_id claim from app_metadata or user_metadata (whichever the project convention is). Before calling createSignedUrl, perform a storage.from('declarations').list(orgPath) or head() to verify object existence — this prevents generating a signed URL for a non-existent or deleted declaration. Write the audit log row to the declaration_acknowledgement table using the service-role admin client (not the user-scoped client) to ensure the write is not blocked by RLS.
Return the signed URL in a JSON response body { url: string, expiresAt: string } — the Flutter client should store expiresAt locally to avoid fetching a URL it knows has expired.
Testing Requirements
Unit tests (Deno test) with mocked Supabase Storage and database clients: assert correct signed URL is returned for valid inputs, assert TTL is clamped to 86400 when 172800 is supplied, assert AuthorizationError when JWT orgId !== path orgId, assert NotFoundError when storage head returns 404, assert audit log insert is called with correct fields. Integration test against Supabase staging: generate URL with TTL=60s and assert the object is downloadable; wait 61 seconds and assert the URL is no longer valid; attempt cross-org URL generation with a JWT for a different org and assert 403.
Org-scoped encryption key management is complex. If keys are not correctly isolated per organization, a breach in one org's key could expose another org's declarations. Additionally, key rotation is not specified but may be needed for compliance, and the current implementation may not support it.
Mitigation & Contingency
Mitigation: Use Supabase Vault or a dedicated secrets management approach for org-scoped key storage. Define the key derivation strategy (per-org master key) in a security design document reviewed before implementation begins. Include key isolation tests in the test suite.
Contingency: If a full per-org key management system cannot be safely implemented within the sprint, fall back to a single platform-level encryption key with strict RLS isolation as a temporary measure, flagging the key rotation gap as a security debt item with a defined resolution milestone.
Push notification delivery to drivers depends on FCM token availability and device connectivity. If a driver has not granted notification permissions or has an expired FCM token, the declaration delivery notification will silently fail, leaving the coordinator unaware and the declaration unacknowledged.
Mitigation & Contingency
Mitigation: Implement delivery status tracking in declaration-notification-service. Fall back to in-app notification and SMS (if configured) when push delivery fails. Expose delivery failure status in the declaration status badge so coordinators can identify and manually follow up.
Contingency: If push delivery proves unreliable, implement a polling-based in-app notification fallback where drivers see pending declarations on next app open, ensuring the workflow can complete even without push notifications.
The acknowledgement service is meant to validate that the driver has fully scrolled through the declaration before confirming. Implementing reliable scroll completion detection in Flutter across different screen sizes and font sizes is technically non-trivial and could be bypassed.
Mitigation & Contingency
Mitigation: Implement scroll position tracking using ScrollController with a threshold (e.g., 95% of content height reached) and record the validated state server-side before allowing acknowledgement submission. Document the approach in the legal sign-off checkpoint noted in the feature documentation.
Contingency: If reliable scroll detection cannot be implemented within the sprint, add a mandatory reading delay timer (e.g., estimated reading time based on word count) as an alternative validation mechanism, pending legal review of the approach.
The driver assignment service must coordinate with the threshold-based expense approval workflow for fees above configured thresholds. If the expense approval workflow interface changes or is not yet stable, the integration point could break or produce incorrect routing behavior.
Mitigation & Contingency
Mitigation: Define a clear interface contract between driver-assignment-service and the expense approval workflow before implementation. Use dependency injection so the expense workflow client can be mocked in tests. Monitor the expense approval feature for interface changes.
Contingency: If the expense approval workflow interface is not stable, implement a direct database insert to the expense records table as a temporary bypass, with a flag indicating manual review is needed, until the stable interface is available.