Implement personnummer extraction and Supabase user persistence
epic-bankid-vipps-login-services-task-006 — Complete the Vipps Authentication Service post-authentication flow: upsert the authenticated Vipps user into Supabase (creating account if new, linking if existing), write the extracted personnummer back to the User Identity Repository with user consent handling, and establish a Supabase session via the Auth Session Manager. This is the core data gap resolution for partner organizations.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 5 - 253 tasks
Can start after Tier 4 completes
Implementation Notes
The Edge Function should: (1) verify the Vipps access token by calling the Vipps userinfo endpoint, (2) look up existing Supabase user by Vipps sub claim using admin API, (3) create or update the user, (4) if consent was granted (passed as a boolean in the request body from mobile), encrypt and upsert the NIN via supabase.rpc('store_encrypted_nin', {...}), (5) create a Supabase session and return the JWT. Keep the NIN in a Deno string variable only as long as needed — delete immediately after the RPC call. On the Flutter side, pass the Vipps access token and the user's consent decision (boolean) to the Edge Function via a POST body. Store the returned JWT using flutter_secure_storage with the key supabase_session_v1.
Then call authSessionManager.setSession(jwt) to trigger the AuthState.authenticated emission. For existing user linking, use the Vipps 'sub' claim as the stable identifier to match against a vipps_sub column on the auth.users metadata — not email, which can change.
Testing Requirements
Unit tests (flutter_test): mock the Edge Function response and verify AuthState transitions for success, failure, and consent-denied paths. Verify flutter_secure_storage.write() is called with the Supabase JWT on success. Verify no write occurs on consent denial. Integration tests: deploy Edge Function to Supabase test project, perform end-to-end Vipps auth flow, verify user record created, NIN stored encrypted, session JWT returned.
Test idempotency: run the upsert twice with the same Vipps identity, verify only one user record exists. Test rollback: simulate database constraint failure mid-upsert, verify no partial records. Security tests: attempt to call the Edge Function with an invalid Vipps access token, verify 401 rejection. Verify NIN column is unreadable via direct Supabase client (RLS).
GDPR test: verify consent denial results in null NIN field.
The PKCE OAuth flow requires the code verifier to survive an app backgrounding during the Vipps redirect, which can trigger OS memory pressure and clear in-memory state. If the verifier is lost between authorization request and callback, the token exchange fails and the user is stranded with a confusing error.
Mitigation & Contingency
Mitigation: Store the PKCE code verifier in AuthTokenStore (Flutter Secure Storage) immediately after generation, before launching the Vipps redirect. Clear it only after a successful or explicitly failed token exchange.
Contingency: If state loss occurs in production, implement a retry flow that generates a new PKCE pair and restarts the authorization URL request, with a user-visible 'Try again' prompt rather than a generic error.
Resuming a Supabase session after biometric verification requires the session token to still be valid. If the session has expired in the background (e.g., after a long device offline period), biometric success will not produce a valid session, and the user will see a confusing 'Face ID worked but still logged out' experience.
Mitigation & Contingency
Mitigation: Before presenting the biometric prompt, check session token expiry. If expired, skip biometrics and route directly to full BankID/Vipps re-authentication. Only offer biometric re-auth if the stored refresh token is still within its validity window.
Contingency: If session expiry during biometric flow occurs in production, implement a graceful transition message ('Your session has expired — please log in again') that preserves the user's last-used authentication method preference.
BankID and Vipps may return different user identifiers (personnummer, phone number, sub claim) that must be correctly linked to an existing Supabase auth user. If the linking logic has edge cases (e.g., user previously registered via email/password), duplicate Supabase accounts may be created.
Mitigation & Contingency
Mitigation: Design the identity linking logic with explicit disambiguation: check for existing users by personnummer before creating a new Supabase identity. Implement the linking via Supabase Edge Function to keep the logic server-side and auditable.
Contingency: Implement an admin-facing account merge tool in the admin portal to resolve duplicate accounts if they occur. Add a Supabase unique constraint on the personnummer field to make duplicates fail loudly rather than silently.
The Vipps nin (personnummer) scope requires explicit approval from Vipps as part of the merchant agreement. If this scope approval is not in place before the production release, the Vipps flow will succeed but return no personnummer, making the primary business value (membership data gap fill) non-functional without user-visible error.
Mitigation & Contingency
Mitigation: Apply for Vipps nin scope approval as part of the merchant onboarding process, well before Phase 2 launch. Implement the service to gracefully handle absent nin claims and show users a clear message if personnummer could not be retrieved.
Contingency: If nin scope is delayed, ship the Vipps login flow without personnummer write-back first (delivering login value immediately) and add personnummer sync as a post-approval update with no UI changes required.