Senior AI Engineer

Sierra is scaling the next generation of conversational AI agents that go beyond simple chat to solve complex customer problems through autonomous reasoning. As a Senior AI Engineer, you will architect and refine the orchestration layers that allow our agents to interact with third-party APIs, maintain state across long-term dialogues, and deliver brand-consistent experiences. You will play a pivotal role in pushing the boundaries of LLM reliability and latency for millions of concurrent global users.

- Design and implement sophisticated agentic workflows that enable LLMs to perform multi-step reasoning and tool use. - Optimize the inference stack to reduce latency and cost while maintaining high conversational quality. - Develop robust evaluation pipelines to continuously benchmark agent performance against real-world customer interactions. - Collaborate with product and design teams to build "human-in-the-loop" systems for complex edge cases. - Stay at the forefront of LLM research to integrate new techniques in long-context window management and structured output generation. - Mentor junior engineers and contribute to codebase scalability through rigorous code reviews and architecture design. - Partner with infrastructure teams to manage the lifecycle of models deployed across global regions.

- 5+ years of software engineering experience with at least 2 years focused on production-grade AI/ML systems. - Proven track record of deploying LLM-based applications using frameworks like LangChain, LlamaIndex, or custom orchestration layers. - Deep understanding of prompt engineering, fine-tuning methodologies, and RAG architectures. - Expert-level proficiency in Python and experience with distributed systems in high-traffic environments. - Experience with evaluation frameworks to measure and improve agentic accuracy, safety, and hallucination rates. - Strong product intuition with the ability to translate consumer brand voice into technical AI constraints. - Background in building scalable APIs and integrating with complex enterprise backends (ERP, CRM, etc.).