Senior Python/FastAPI/React Engineer

We need a senior engineer to build and maintain a scalable AI platform. You will develop backend services, improve system performance, and support frontend integration for a growing product. The role includes working on core platform architecture, optimizing workflows, and helping deliver reliable features for an expanding user base. Experience building production-ready applications and collaborating across teams is important. Our core tech stack includes **Python / FastAPI**, **Supabase / PostgreSQL**, and **React / TypeScript**. What You Will Do * Debug Existing Systems: Trace complex microservice integration failures and fix silent runtime/data-flow bugs where code looks correct on paper but fails in production. * Ship Scoped Features: Execute implementation plans from handover documentation with high autonomy and precise code quality. * Database Management: Write clean PostgreSQL migrations, optimize queries, inspect database state, and handle JSONB fields using Supabase. * API & Integrations: Build and harden REST endpoints, wire up OAuth integrations, and construct a multi-turn SMS session threading layer via Twilio webhooks. * Light Frontend Work: Make occasional UI tweaks or debug data flow issues in our React/TypeScript frontend. Requirements *4+ years of production Python with deep FastAPI experience. *Strong PostgreSQL skills: Schema design, JSONB, migrations, and low-level query debugging. *Proven codebase navigation: Expertise jumping into messy, non-greenfield codebases and tracing root causes quickly. *Solid Git/PR habits: Clear commit histories, detailed PR explanations, and a focus on production stability. *Strong written communication: Clear, asynchronous English for ticket updates and documentation. Nice-to-Haves * Practical knowledge of **React / TypeScript**. * Experience with **Twilio APIs** (SMS handling, voice, and webhook sessions). * Exposure to **WebRTC / real-time audio** or AI observability frameworks (**Langfuse, LiteLLM**). How to Apply Please submit your proposal along with a response to the following prompt: Describe the most complex inherited codebase you have debugged. What was the specific runtime issue, how did you trace it through the system, and what steps did you take to resolve it? (Note: Generic or templated proposals will be ignored automatically.)