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LyftLyft

Machine Learning Engineer, Safety and Customer Care AI

Builds and productionizes post-trained open-source language models and AI agents for safety and customer-care workflows. The role requires applied ML/AI experience, Python and PyTorch expertise, agentic development, generative AI evaluation, and real-time deployment experience.

About the job

Responsibilities

  • Conduct literature reviews and build post-training frameworks and lifecycles.
  • Curate and process human and synthetic data for SFT, LoRA, RLHF, RLAIF, and RLVR, iterating on model quality for support and safety tasks.
  • Develop, evaluate, and productionize AI agents, designing tools, state, and control flow in LangGraph or equivalent frameworks.
  • Take agents through the full agent development lifecycle.
  • Build and scale evaluation frameworks, golden sets, rubric-based grading, LLM-as-judge systems where appropriate, and regression testing.
  • Ship models and agents into real-time production, with monitoring and guardrails for safe operation at millions of interactions per month.
  • Apply traditional machine learning, including classification, ranking, and gradient-boosted trees, where appropriate.
  • Partner with product, operations, and data science teams to scope problems and define success metrics.

Requirements

  • 3+ years of industry experience in applied ML/AI, inclusive of an MS or PhD in Computer Science, Machine Learning, Artificial Intelligence, or a related technical field.
  • Post-training experience with open-source models.
  • Hands-on familiarity with fine-tuning and preference-tuning paradigms such as SFT, LoRA, RLHF, RLAIF, and RLVR.
  • Experience building and shipping agents with LangGraph or equivalent frameworks.
  • Experience with the full agent development lifecycle.
  • Experience designing metrics and building offline and online evaluations for generative systems.
  • Experience deploying ML/AI applications to real-time production use cases.
  • Strong programming skills in Python.
  • Hands-on experience with PyTorch.

Nice-to-haves

  • Experience applying ML/AI to customer support or trust and safety workflows, including agent assist, routing, resolution recommendation, or abuse and safety detection.
  • PhD in Computer Science, Machine Learning, Statistics, or a related technical field.
  • Publications at top-tier peer-reviewed research venues such as NeurIPS, ICML, ICLR, ACL, or CVPR.

Compensation and Benefits

  • Expected base pay range in the Toronto area: CAD $118,800–$148,500, excluding potential equity, bonus, and benefits.
  • Extended health and dental coverage, life insurance, and disability benefits.
  • Mental health benefits.
  • Family-building benefits.
  • Child care and pet benefits.
  • Lyft-funded Health Care Savings Account.
  • RRSP plan with company match.
  • Flexible paid time off for salaried team members; hourly team members receive 15 days paid time off, with an additional day for each year of service.
  • 18 weeks of paid parental leave for eligible biological, adoptive, and foster parents.
  • Subsidized commuter benefits and Lyft ride credits.

Skills

Python, PyTorch, LangGraph, LLMs, Sft, Lora, RLHF, Rlaif, Rlvr, Model Fine-Tuning, AI Agents, Machine Learning Evaluation, Real-Time Production, Gradient-Boosted Trees

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