Rangel Koli

About

Backend engineer who built and scaled a zero-to-one social product backend using Supabase (Postgres, Edge Functions, Auth, Realtime) plus Neo4j for graph-based friend recommendations. Demonstrates strong production rigor: staged rollouts with metrics, incident rollback/postmortems, and complex schema refactors using expand-contract/dual-write with reconciliation and feature flags. Notably proactive about edge cases like geo-boundary realtime delivery and idempotent retry safety.

Key Strengths

• Designed zero-to-one backend architecture using Supabase + Neo4j for a social app
• Pragmatic scalability/high-availability tradeoff decisions with multi-database complexity management
• Implemented geo-based realtime feed filtering using geohash with staged zone rollouts
• Metrics-driven performance validation (latency, query performance, failed deliveries, boundary edge cases)
• Strong API reliability/security practices in FastAPI (JWT, Pydantic validation, CORS lockdown, rate limiting, structured logging)
• Incident response with fast rollback, bottleneck isolation, query optimization, caching, and safe roll-forward
• Led high-risk schema refactor using expand-contract, dual writes, batched backfills, reconciliation, and feature-flagged cutover
• Diagnosed and mitigated tail-latency spikes during dual-write by canarying traffic and throttling backfill
• Deep Supabase/Postgres RLS expertise (policies + underlying grants; auth.uid null failure mode testing)
• Improved robustness by introducing idempotency keys + uniqueness constraints to prevent duplicate side effects on retries

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