Machine Learning Engineer – Lumen Enterprise Models (SWE-focused LLMs) at cosinecosine · London Office

Workplace: On-site

Type: fulltime

Posted: 2026-10-15

Skills: DockerJob title: Machine Learning Engineer – Lumen Enterprise Models (SWE-focused LLMs) Location: London; full in-office working as default Start date: ASAP Reports to: CEO Compensation: Salary and Equity options available for discussion Application deadline: 08/11/26 at 23:59 UK time HELP TRAIN THE SOFTWARE ENGINEERS OF THE FUTURE Cosine is building autonomous software-engineering systems for organisations where reliability, security and control matter most. Our Lumen Enterprise models are designed to work across real codebases. They need to understand unfamiliar architectures, make changes across multiple files, use tools, run tests and produce software that engineers can maintain and trust. We’re looking for a Machine Learning Engineer to help train and improve these models. You’ll work across the full training stack, including pre-training, supervised fine-tuning and reinforcement learning. This is a truly unique role that will provide exposure across all areas of the model training lifecycle. WE’re looking for someone who is just as happy to profile the training loop, identifying performance bottlenecks and memory leaks, as implementing new RL algorithms. This is a hands-on role for someone who enjoys working close to the model and cares about the quality of the software it produces. THE ROLE You’ll work closely with research, infrastructure and product to answer questions such as: - What should Lumen learn next? - Which data and environments will teach it most effectively? - How should we reward correct, maintainable and useful software? - How do we train models to work across large repositories and long contexts? - How do we know when a model is genuinely better for engineers? The models you train will write code, use development tools, run tests and receive feedback from real software-engineering environments. Your work will directly influence how …truncated… of thinking, and we’re committed to creating an inclusive and respectful workplace. We encourage applicati…Sign in to see the original postingBrowse more developer jobs on RoleBurst