OmniPostOmnichannel Notification Delivery Platform

Prioritized queues, automated circuit breaker provider fallback, exponential backoff retries, and timezone-aware quiet-hours compliance.

F1-F7: Relational State Ledgers

Nine relational tables powering immutable delivery tracking, versioned templates, user preferences, and lease-based queue states.

Strict request idempotency with E.164 phone and email normalization, and 4-tier priority preemption (URGENT, HIGH, NORMAL, LOW).

Jinja2 SandboxedEnvironment preventing template injection attacks while enabling dynamic conditionals, loops, and language fallback.

Polymorphic drivers for Email, SMS segments, and Webhook HMAC-SHA256 with deterministic cost and health failover.

Asynchronous workers with token bucket rate limiting, exponential backoff with full jitter, and manual DLQ redrive APIs.

Enforces quiet hours with midnight wrap-around and rolling 24-hour frequency capping across global timezones with DST.

FastAPI REST API protected by SHA-256 hashed API keys, deny-by-default RBAC, and adversarial multi-tenant data isolation.

Comprehensive architectural deep dive modeling 10 million notifications/day across 17 technical chapters and an ADR log.

150+ categorized technical questions and answers paired with first-person 'Say It Out Loud' interview rehearsal scripts.