Founding ML Research Engineer

ABOUT THE ROLE As the Founding ML Research Engineer on a consumer AI assistant team, you will lead hands-on research and engineering to improve how the assistant responds, uses tools, and acts safely. Your work will shape product quality while balancing reliability, latency, and model costs. WHAT YOU'LL DO - Build evaluation systems that turn real conversations and user preferences into trustworthy measures for product decisions. - Post-train models using supervised fine-tuning, preference tuning, and distillation, then ship the improvements to production. - Develop and evaluate model routing that uses smaller models for routine requests and more capable models when needed. - Manage the tradeoffs among response quality, latency, and cost across the product. - Improve agent reliability on websites without APIs, including navigation, sign-in, and checkout flows. - Test for adversarial inputs, data exposure, and unintended actions, then build safeguards and evaluations. - Apply ML to memory, retrieval, tool selection, and decisions about when to act or ask the user. - Review real conversations, identify opportunities for improvement, and help set research direction as the team grows. WHAT WE'RE LOOKING FOR - At least 4 years of ML or software engineering experience in an AI lab, AI product company, or equivalent environment. - Hands-on experience fine-tuning or post-training large language models and shipping results to production. - Experience designing evaluations, such as LLM judges, human preference data, or traffic replay, that support product decisions. - Background in one or more areas: red teaming, browser or computer-use agents, model routing, or production agents with tool use and long-running memory. - Strong Python skills and familiarity with the ML stack, plus comfort using TypeScript for product code. - A founding-team mindset, with the ability and interest to take ownership and set research direction. COMPENSATION & BENEFITS Annual salary range: $200,000 to $300,000. Visa sponsorship is not available. LOCATION Full-time, on-site in San Francisco, California.