Research Engineer, Mid-Training

San Francisco FullTime

Posted 1mo ago

Job Location

San Francisco

Tech Stack

Remote Work Policy

On-site

Employment Type

FullTime

Categories

AI Research Engineer

About the job

We are an applied AI lab building end-to-end software agents, known for creating Devin, the first AI software engineer. Our team is composed of highly talented individuals with backgrounds in competitive programming and leadership roles at cutting-edge AI companies. We are tackling significant global challenges and developing AI capable of real-world reasoning. This role focuses on the critical 'mid-training' phase, bridging pre-training and post-training to refine raw model capabilities. You will be instrumental in shaping our models' fundamental abilities by owning late-stage training decisions, including data mix and quality, annealing schedules, context length extension, capability injection, and synthetic data strategies.

Responsibilities

  • Design and iterate on high-quality data mixtures for late-stage and annealing training runs.
  • Develop principled methods for sourcing, filtering, and weighting data to sharpen model capabilities.
  • Drive targeted improvements in coding, mathematics, and long-horizon reasoning through curated data strategies.
  • Develop and evaluate synthetic data pipelines for generating training signal at scale.
  • Research and optimize multi-stage learning rate schedules, warmup strategies, and compute allocation.
  • Research and implement methods for extending effective context length without degrading performance.
  • Build evaluations to distinguish real capability improvements from benchmark overfitting.
  • Measure how mid-training interventions scale with compute and data.
  • Develop new approaches when existing methods hit ceilings.

Requirements

  • Deep familiarity with the LLM training pipeline end to end.
  • Hands-on experience with continual pre-training, annealing, or late-stage data mixing for large models.
  • Strong intuition for data quality, including filtering and curation at scale.
  • Experience developing or evaluating synthetic data pipelines for capability improvement.
  • Proficiency in Python and deep learning frameworks like PyTorch.
  • Comfort debugging distributed training at scale.
  • Strong fundamentals in optimization, statistics, and ML theory.
  • Ability to distinguish real effects from noise, instability, and overfitting.
  • A track record of original contributions (publications, open-source impact, or internal results).
  • Comfort operating in ambiguous, fast-moving environments.

About Cognition

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