The opportunity
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…
What you'll 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.
What they're looking for
- 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.
