Senior Python Backend Engineer for Enterprise-Grade AI Infrastructure (FastAPI, Postgres)

We are an early-stage venture building enterprise infrastructure for AI agents. We are looking for one strong backend developer to build the first production version of our platform with us. This is not a prototype or a proof of concept. The system will be reviewed by enterprise security and compliance teams, so it needs to be built to that standard from the start: real authentication, tenant isolation, complete audit records, and a deployment path that works both hosted and inside a customer's own cloud environment. What we need built A well-documented REST API that external developers integrate into their own systems A rules and evaluation service that returns results within a sub-second budget Append-only, tamper-evident record keeping with full context on every transaction, queryable and exportable A lightweight Python client library so customers can integrate with minimal changes to their code Containerized deployment, with configuration for both a hosted service and a customer-managed environment A simple internal admin interface for configuration and review, after the API is solid Required skills Strong Python with production FastAPI experience Postgres, including schema design for high-write, append-only workloads Designing and versioning public-facing APIs used by external developers Authentication, authorization, role-based access control, and multi-tenant architecture Latency-sensitive services in a live request path, with real experience holding a p95 target Docker, plus deployment on AWS, GCP, or Azure Structured logging, tracing, and monitoring Testing discipline and clear written communication in English Nice to have Integrating LLM APIs into backend services, including timeouts, retries, and fallbacks Familiarity with agent frameworks such as LangGraph or LlamaIndex Rules engines, policy-as-code, approval workflows, or risk and fraud decisioning systems Compliance-heavy environments (fintech, healthcare, regtech) where audit trails were a hard requirement Experience with enterprise security reviews, SOC 2 readiness, or EU data residency and privacy requirements