Document service contracts and Riverpod provider graph
epic-achievement-badges-services-task-018 — Write developer documentation for the four badge backend services: method signatures with parameter and return type descriptions, Riverpod provider dependency graph (who depends on whom), idempotency guarantees, honorar threshold counting rules for Blindeforbundet, tier eligibility calculation formula, and known edge cases. Documentation targets backend engineers integrating badge evaluation and UI engineers consuming provider state.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 8 - 48 tasks
Can start after Tier 7 completes
Implementation Notes
Use Dart doc-comment style (///) for inline documentation on service classes and methods so that dart doc can generate HTML output. Supplement with a standalone BADGE_SERVICES.md file for the provider dependency graph and the cross-cutting rules (idempotency, honorar thresholds, eligibility formula). For the Riverpod graph, list providers in dependency order top-to-bottom; use Mermaid graph TD syntax if the repo supports it in markdown. Document the honorar counting rules using a table with columns: Threshold Number, Honorar Type, Trigger Condition.
For the eligibility formula, use the format: tierScore = f(activityCount, honorarCount, periodDays) with variable definitions below. Cross-reference the integration test file so readers can verify the documented behavior against executable tests.
Testing Requirements
No automated tests for documentation itself. However, a peer review by one backend engineer and one UI engineer is required before the documentation is considered complete.
Reviewers must confirm that: (1) they can understand the provider graph without reading source code, (2) idempotency guarantees match the integration tests written in task-017, (3) the honorar threshold rules match the test fixture values used in task-017.
peer-mentor-stats-aggregator must compute streaks and threshold counts across potentially hundreds of activity records per peer mentor. Naive queries (full table scans or N+1 patterns) will cause slow badge evaluation, especially when triggered on every activity save for all active peer mentors.
Mitigation & Contingency
Mitigation: Design aggregation queries using Supabase RPCs with window functions or materialised views from the start. Add database indexes on (peer_mentor_id, activity_date, activity_type) before writing any service code. Profile all aggregation queries against a dataset of 500+ activities during development.
Contingency: If query performance is insufficient at launch, implement incremental stat caching: maintain a peer_mentor_stats snapshot table updated on each activity insert via a database trigger, so the aggregator reads from pre-computed values rather than scanning raw activity rows.
badge-award-service must be idempotent, but if two concurrent edge function invocations evaluate the same peer mentor simultaneously (e.g., from a rapid double-save), both could pass the uniqueness check before either commits, resulting in duplicate badge records.
Mitigation & Contingency
Mitigation: Rely on the database-level uniqueness constraint (peer_mentor_id, badge_definition_id) as the final guard. In the service layer, use an upsert with ON CONFLICT DO NOTHING and return the existing record. Add a Postgres advisory lock or serialisable transaction for the award sequence during the edge function integration epic.
Contingency: If duplicate records are discovered in production, run a deduplication migration to remove extras (keeping earliest earned_at) and add a unique index if not already present. Alert engineering via Supabase database webhook on constraint violations.
The badge-configuration-service must validate org admin-supplied criteria JSON on save, but the full range of valid criteria types (threshold, streak, training-completion, tier-based) may not be fully enumerated during development, leading to either over-permissive or over-restrictive validation that frustrates admins.
Mitigation & Contingency
Mitigation: Define a versioned Dart sealed class hierarchy for CriteriaType before writing the validation logic. Review the hierarchy with product against all known badge types across NHF, Blindeforbundet, and HLF before implementation. Build the validator against the sealed class so new criteria types require an explicit code addition.
Contingency: If admins encounter validation rejections for legitimate criteria, expose a 'criteria_raw' escape hatch (JSON passthrough, admin-only) with a product warning, and schedule a sprint to formalise the new criteria type properly.