Senior AI Agent Systems Engineer

Phaxis; Los Angeles (CA); On-site; USD 150,000 - 210,000; Full time

Job summary

Phaxis is a well-funded technology company building the next generation of AI-powered consumer products. This hands-on role focuses on multi-agent systems, ownership of architecture, reliability, and performance from prototype to production.

You will work at the intersection of orchestration, LLM infrastructure, and production engineering to turn emerging AI capabilities into scalable products used by real consumers.

Qualifications

• Experience building production-grade LLМ-powered applications.
• Hands-on backend engineering with Python and/or Node.js.
• Experience with tool calling, structured outputs, and prompt engineering.
• Ability to design multi-step execution loops with state management and failure recovery.

Responsibilities

• Build and operate multi-agent systems that plan, coordinate, and execute tasks across tools and services.
• Develop agentic coding workflows enabling autonomous code generation, testing, and iteration within guardrails.
• Design orchestration layers for planning, supervision, retries, and long-running workflows.
• Build backend infrastructure for agent execution: queues, pub/sub, durable state, concurrency controls, and recovery.
• Instrument agent behavior across success, latency, and cost metrics; enable feedback loops from users and teams.
• Collaborate with Product and Design to translate problems into AI-powered products.

Skills

Python

Node.js

LLM apps

Agentic workflows

Distributed systems

Docker CI/CD

Tools

Docker

AWS

GCP

Kubernetes

Job description

Phaxis is a well-funded technology company building the next generation of AI-powered consumer products. This hands-on role focuses on multi-agent systems, ownership of architecture, reliability, and performance from prototype to production.

You will work at the intersection of orchestration, LLM infrastructure, and production engineering to turn emerging AI capabilities into scalable products used by real consumers.