Document data layer contracts and encryption design
epic-contact-detail-and-edit-foundation-task-018 — Write developer documentation covering: typed interfaces for all repository methods, field-encryption-utils API surface, MaskedFieldResult contract, contact-form-validator ValidationResult structure, and the NHF 5-chapter affiliation rule. Include a sequence diagram for the encrypted field fetch-decrypt-display flow so service and UI tier developers have stable contracts to build upon.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 8 - 48 tasks
Can start after Tier 7 completes
Implementation Notes
Use Mermaid syntax for the sequence diagram (GitHub renders it natively). Structure the document with the following H2 sections: Overview, ContactDetailRepository API, AssignmentRepository API, FieldEncryptionUtils API, MaskedFieldResult Contract, ContactFormValidator & ValidationResult, NHF 5-Chapter Affiliation Rule, Riverpod Provider Dependency Graph, Testing Override Examples. Keep prose minimal — prefer typed method signatures and bullet lists over paragraphs. The sequence diagram must include the masked fallback branch (alt/else block in Mermaid).
Cross-reference the relevant test file from task-016 so readers can see the contracts exercised. This document is a living contract — note at the top that it must be updated whenever a public interface changes.
Testing Requirements
No automated tests for documentation. However, the document must be technically reviewed: a second developer should attempt to implement a stub service using only the documentation (without reading source code) and confirm all required information is present and unambiguous.
Record the review outcome as a PR comment.
Blindeforbundet's encryption key retrieval mechanism may not be finalised at implementation time, or session key availability via Supabase RLS may be inconsistent, causing decryption failures that expose masked placeholders to users and degrade the experience.
Mitigation & Contingency
Mitigation: Agree with Blindeforbundet on key storage and retrieval contract before implementation starts. Prototype key retrieval in a spike against the staging Supabase instance and validate the full decrypt/verify cycle with real test data before committing to the implementation.
Contingency: Implement a fallback that shows a 'field temporarily unavailable' state with a retry affordance. Log decryption failures server-side for audit. Escalate to Blindeforbundet stakeholders to unblock key management before the service tier epic begins.
NHF contacts may belong to up to 5 chapters, each governed by separate RLS policies. A coordinator's chapter scope may not cover all affiliations, causing partial profile reads or silent data omissions that are difficult to detect in tests.
Mitigation & Contingency
Mitigation: Map all RLS policy combinations for multi-chapter contacts early. Write integration tests that create contacts with 5 affiliations and query them from coordinators with varying chapter scopes. Use Supabase's RLS test utilities to verify row visibility per role.
Contingency: Add an explicit 'affiliation partially visible' state in the repository response model so the UI can communicate scope limitations to the coordinator rather than silently showing incomplete data.
Organisation-specific validation rules (e.g., NHF chapter limit, Blindeforbundet encrypted field edit flow) may expand in scope during implementation as edge cases are discovered, causing the validator to grow beyond the planned complexity.
Mitigation & Contingency
Mitigation: Define the complete validation rule set with product and org stakeholders before coding begins. Document each rule with its source organisation and acceptance test. Use a rule registry pattern so new rules can be added without modifying core validator logic.
Contingency: Timebox validator enhancements to 2 hours per additional rule. Defer non-blocking rules to a follow-on maintenance task rather than blocking the epic delivery.