AI Systems Engineer, Codex Agents

AI Systems Engineer - Codex Core Agents


About The Team
The Codex Core Agents team builds the agent harness that turns model capability into real-world action. We own the systems around the model: prompting and interpreting model outputs executing actions safely in real environments and feeding production experience back into better models and better agent behavior.
This team sits close to research and works across the stack: harness model interaction inference sandboxed execution orchestration evals production reliability and the performance envelope around tokens latency cost capacity and quality. The harness is open source and increasingly part of how models are trained and evaluated making this one of the highest-leverage layers in Codex.

About The Role
Were looking for engineers to build the AI systems that make Codex agents dependable in production. The ideal candidate is an agent-systems builder: hands-on across low-level systems and ML workflows able to debug Codex behavior end to end across the harness model behavior inference/runtime stack GPU fleet and product surface.

Youll work with research infrastructure and product to design agent harness capabilities run experiments and ablations across the model system prompt harness stack build frameworks for assessing production agent performance and turn messy failures into durable improvements.

What Youll Do

• Design and build the core agent harness and execution loop that lets Codex agents interpret model outputs use tools execute code and complete long-horizon tasks safely.

• Build sandboxing isolation orchestration state and workflow infrastructure for agents operating in real development environments.

• Develop evaluation experimentation and debugging systems that distinguish harness issues model behavior inference/runtime issues and product failures.

• Run ablations across prompts model-facing interfaces context construction tool-use strategies and harness behavior to improve solve rate reliability latency and cost.

• Improve observability profiling and diagnostics across the agent stack from backend systems to inference GPUs and fleet capacity.

• Work closely with research to make the harness trainable measurable and useful for improving frontier agentic models.

• Build shared primitives that make Codex faster safer more reliable and easier for other teams and open-source users to build on.
  
  You Might Be A Good Fit If You

• Have built or operated production systems in distributed systems infrastructure developer tooling sandboxing virtualization cloud platforms or ML systems.

• Enjoy working across layers: Rust systems code Python configuration layers APIs agent orchestration evals logs/traces inference behavior runtime constraints and user outcomes.

• Have hands-on experience with LLM applications coding agents evals model deployment inference compiler/runtime performance or developer platforms.

• Care deeply about reliability safety performance debuggability and clean abstractions.

• Can debug from evidence and move quickly from ambiguous production failures to practical durable fixes.

• Want to work close to research while still shipping changes to production

• Still write meaningful code show strong ownership and can lead scoped or multi-team AI systems work.

Bonus Points

• Deep Rust systems sandboxing isolation or low-level platform experience.

• Experience with coding agents agent harnesses tool-using LLM systems model evals or post-training feedback loops.

• Background in compilers kernels runtimes inference optimization GPU systems benchmarking profiling or performance engineering.

• Experience building production infrastructure used by many engineers or users under demanding reliability and security constraints.

• Open-source infrastructure or developer-platform work with strong taste for APIs and usability.

About OpenAI

OpenAI is an AI research and deployment company dedicated to ensuring that general-purpose artificial intelligence benefits all of humanity. We push the boundaries of the capabilities of AI systems and seek to safely deploy them to the world through our products. AI is an extremely powerful tool that must be created with safety and human needs at its core and to achieve our mission we must encompass and value the many different perspectives voices and experiences that form the full spectrum of humanity.

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Required Experience:

Unclear Seniority