About the Role Join an early-stage consumer AI company as its founding product engineer, with end-to-end ownership of an AI assistant and its user experience. You will shape how the assistant reasons, communicates, and takes action, combining hands-on engineering with close product collaboration and regular user feedback. What You'll Do • Build the assistant's agent architecture, including tool-use loops, memory, context assembly, prompt design, and model routing. • Create evaluation systems with conversation replay, turn-level assessment, and regression tests to guide release decisions. • Own product experiences across web and mobile, including onboarding, follow-ups, group conversations, approvals, and trusted-network features. • Ship features from discovery through experimentation and launch, using user feedback and product data to guide iteration. • Develop integrations with services such as email, calendars, bookings, and payments, along with reliable approval and recovery flows. • Review conversation transcripts, speak with users, and help set engineering standards as the team grows. What We're Looking For • At least 4 years of software engineering experience at an AI product company, AI lab, or consumer product company. • Production experience building agents with tool use, memory, and long-running conversations, plus evaluation systems trusted for release decisions. • Full-stack experience with TypeScript, React, Next.js, and Postgres. • Experience with third-party APIs, OAuth, payments, or agent tooling such as function calling, MCP servers, or browser automation. • A record of owning features end to end and demonstrating measurable product impact. • Strong product judgment, experience with AI-assisted development workflows, and the ability to validate and take responsibility for shipped work. • Experience leading a growing engineering team while remaining hands-on; post-training or fine-tuning experience is a plus. Compensation & Benefits Base salary: $200,000 to $300,000 annually. Visa sponsorship is not available. Location On-site in San Francisco, California.