Own the architecture, roadmap, and production operation of search and recommendation systems across discovery surfaces. Lead retrieval, ranking, personalization, relevance measurement, experimentation, OpenSearch infrastructure, signal pipelines, and candidate generation. Partner with Product, Data, ML, and Trust & Safety to balance relevance, freshness, safety, latency, and cold-start behavior. Establish engineering standards, instrumentation, rollout processes, and runbooks while mentoring backend engineers.