Define badge criteria evaluator interfaces
epic-achievement-badges-evaluation-engine-task-001 — Define TypeScript interfaces and abstract base classes for the three criteria evaluator types: threshold-based, streak-based, and training-completion. Establish the CriteriaEvaluator contract that all evaluators must implement, including input/output types for aggregated peer mentor stats and evaluation results.
Acceptance Criteria
Technical Requirements
Implementation Notes
Place all interface files under supabase/functions/_shared/badge-evaluation/ so they are importable by any Edge Function in the project. Use Deno's native TypeScript support — no tsconfig.json is needed for Edge Functions, but add // @ts-check comments if running in a mixed environment. Keep the generic CriteriaEvaluator
Name the barrel file mod.ts following Deno conventions rather than index.ts if the project already uses mod.ts convention — check existing Edge Functions for the pattern in use.
Testing Requirements
Type-level tests using tsd or TypeScript's own type assertion patterns to verify assignability: assert that a valid ThresholdCriteriaConfig satisfies ThresholdCriteriaConfig, that an invalid config (missing required field) causes a compile error. Unit test the AbstractCriteriaEvaluator.validate() helper with a concrete test subclass — verify it throws BadCriteriaConfigError when required fields are absent and does not throw when all fields are present. Run deno test with --check flag to confirm all type exports are valid Deno modules.
Supabase Edge Functions may experience cold start latency of 500ms–2s when they have not been invoked recently. If evaluation latency consistently exceeds the 2-second UI expectation, the celebration overlay timing SLA cannot be met without the optimistic UI fallback from the UI epic.
Mitigation & Contingency
Mitigation: Keep the edge function warm by scheduling a lightweight health-check invocation every 5 minutes in production. Optimise the function size to minimise Deno module load time. Implement the optimistic UI path in badge-bloc (from the UI epic) as the primary UX path so cold start only affects server-side reconciliation, not perceived responsiveness.
Contingency: If cold starts remain problematic, migrate badge evaluation to a Supabase database function (pl/pgsql) triggered directly by a database trigger on activity insert, eliminating the Edge Function overhead entirely for the evaluation logic while keeping Edge Function only for FCM notification dispatch.
Supabase database webhooks can fail silently if the edge function returns a non-2xx response or times out. A missed webhook means a peer mentor does not receive a badge they earned, which is both a functional defect and a trust issue for organisations relying on milestone tracking.
Mitigation & Contingency
Mitigation: Implement idempotent webhook processing: the edge function reads the activity ID from the webhook payload and checks whether evaluation for this activity has already run (via an audit log query) before proceeding. Add Supabase webhook retry configuration (3 retries with exponential backoff). Monitor webhook failure rates via Supabase logs alert.
Contingency: Implement a nightly reconciliation job (Supabase scheduled function) that scans all activities from the past 24 hours, re-evaluates badge criteria for any peer mentor with no corresponding evaluation log entry, and awards any missing badges. Alert operations if reconciliation awards more than 5% of badges, indicating systematic webhook failure.
The evaluation service loads badge definitions per organisation, but a misconfigured RLS policy or incorrect organisation scoping in the edge function could cause one organisation's badge criteria to be evaluated against another organisation's peer mentor activity data, leading to incorrect or cross-contaminated badge awards.
Mitigation & Contingency
Mitigation: The edge function must extract organisation_id from the webhook payload activity record and pass it explicitly to every database query. Write a security test that seeds two organisations with distinct badge definitions and verifies that evaluating a peer mentor in org A never reads or awards org B definitions. Use Supabase service role key only within the edge function, never the anon key.
Contingency: If cross-org contamination is detected in audit logs, immediately disable the edge function webhook, run a targeted SQL query to identify and revoke incorrectly awarded badges, notify affected organisations, and perform a full security review of all RLS policies on badge-related tables before re-enabling.