Container Architecture

The Attendrix platform is divided into four decoupled container tiers: Client, Gateway, Persistence, and Serverless Compute.

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1. Client Tier: Flutter Mobile Container

• Runtime: Flutter 3.x with Dart 3 on Android and iOS.
• Framework: FlutterFlow visual architecture combined with handwritten custom actions and structs.
• Key Modules:
  • FFAppState: Global reactive in-memory state tree.
  • OfflineRoutingCache: In-memory storage of the 152k-pair pedestrian distance matrix.
  • FlutterSecureStorage: Encrypted storage for Supabase JWT refresh tokens.
  • syncAppData.dart: Tiered data synchronization engine managing cache invalidation.

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2. Gateway & Authentication Tier: Supabase Kong & GoTrue

• Reverse Proxy: Kong API Gateway running on port 443 with TLS 1.3 termination.
• Authentication: GoTrue issuing signed RS256 / HS256 JWTs containing the user's sub (UUID) and role (authenticated).
• PostgREST: High-performance HTTP-to-SQL translation engine converting REST calls directly into parameterized PostgreSQL queries.

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3. Serverless Compute Tier: Deno Edge Isolates

• Runtime: Deno runtime on V8 isolates with sub-20ms cold-start latency.
• Security Context: Authenticated with the internal SUPABASE_SERVICE_ROLE_KEY, giving Edge Functions audited administrative access to Vault and PGMQ queues.
• Workers:
  • google-calendar-sync-worker: Reconciles calendar events using deterministic IDs.
  • notify-worker: Dispatches multi-tone push alerts via OneSignal.
  • notify-scheduled-evaluator: Cron-triggered batch evaluator for upcoming events.
  • google-calendar-auth: PKCE OAuth URL generation and code exchange.
  • google-calendar-disconnect: Revocation and secondary calendar deletion.
  • fetch-apod: Nightly NASA APOD ingestion.

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4. Persistence Tier: PostgreSQL 17

• Engine: PostgreSQL 17 running on AWS EC2 instances in ap-south-1.
• Extensions Active:
  • pg_net: Asynchronous HTTP requests from within PostgreSQL.
  • pgmq: Lightweight transactional message queuing.
  • postgis & postgis_raster: Spatial geometry and geography support.
  • pgrouting: Graph traversal and shortest-path calculation.
  • pg_stat_statements: Real-time query performance monitoring.
  • pgcrypto & supabase_vault: AES-256 secret encryption.