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GhostPosted Oct 15, 2026
Member of Technical Staff - Post-Training
San Franciscofull timeOn SiteseniorH1B: no
Ghost Member of Technical Staff - Post-Training at Ghost post-trains open models to power personal agents running locally on Core. The role focuses on improving tool use, reasoning, and execution across complex tasks through supervised fine-tuning and reinforcement learning.
Responsibilities
- Post-train open models to power personal agents that run locally on Core.
- Improve tool use, reasoning, and reliable execution across complex, multi-step tasks.
- Build training datasets and feedback pipelines grounded in realistic agent workflows.
- Develop supervised fine-tuning and reinforcement learning methods that translate model capability into useful product behavior.
- Build evaluations that measure task completion, personalization, and when agents should act or ask for guidance.
- Work closely with the agent and inference teams to improve quality within on-device memory, compute, and latency constraints.
Qualification
Strong Python and PyTorch skillsFamiliarity with tool-using agentsStrong experimental judgment
Required
- Experience post-training language models through supervised fine-tuning, reinforcement learning, or preference optimization.
- Strong Python and PyTorch skills, with experience building and debugging training pipelines.
- Experience creating datasets and evaluations that produce measurable improvements in model behavior.
- Familiarity with tool-using agents, multi-step environments, and the challenges of training against task outcomes.
- Strong experimental judgment: you can diagnose failures, test hypotheses, and distinguish benchmark gains from meaningful product improvements.
Company
Ghost
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