Hark

Member of Technical Staff, Frontier RL Environments

Hark
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10 days ago
San Jose, CA, USASenior

Base Salary

$180k - $450k/yr

Responsibilities

  • Design and build RL environments and tasks for long-horizon planning, tool and computer use, multimodal interaction, and hardware-based agent behavior.
  • Architect reward functions, graders, and task curricula that determine what environments teach or reveal.
  • Scale environment infrastructure to run thousands of tasks and rollouts in parallel across simulated settings and real agentic or hardware sessions.
  • Influence major training-run decisions and validate whether resulting model improvements work in practice.
  • Build self-improvement loops in which models generate, grade, and refine their own training environments.
  • Translate ambiguous behavioral concerns into hypotheses, experiments, pipelines, analyses, and follow-up decisions.

Requirements

  • Strong machine-learning background with hands-on experience training or fine-tuning large language, multimodal, or equivalent models.
  • Hands-on experience building RL environments, simulators, or task suites such as Gym-style interfaces, game engines, browser or OS automation sandboxes, or robotics and hardware simulators.
  • Direct experience with LLMs and post-training techniques including RL, RLHF/RLAIF, reward modeling, graders, synthetic data pipelines, or agentic and tool-using systems.
  • Track record solving ambiguous problems involving loosely defined objectives and noisy data through hands-on engineering and judgment.
  • Ability to form a strong point of view on useful, trustworthy, and pleasant personal-assistant behavior.
  • Ability to collaborate across research, product, infrastructure, data, hardware, and safety teams and communicate clearly between them.
  • Preferred experience with RLHF, DPO, GRPO, PPO, or similar algorithms applied to language, code, or agentic settings.
  • Preferred familiarity with agent benchmarks and evaluation environments including OSWorld, Toolathlon, and GDPval.
  • Preferred research or publication-level experience in reward-model design, reward signals, or reward-hacking mitigation.
  • Preferred experience with trajectory-based training, imitation learning, data distillation, computer use, GUI agents, multimodal tool-using systems, or 100B+ parameter model training.
  • Open-source ML contributions or publications at venues such as NeurIPS, ICML, ICLR, EMNLP, or COLM are preferred.

Benefits

  • Full-time position.
  • US base salary range of $180,000-$450,000 annually.
  • Total compensation may include additional components and benefits depending on the role.

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About Hark

1-10 employees
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