Staff Product Engineer, Enterprise AI

We're building Thunderbolt (https://github.com/thunderbird/thunderbolt (https://github.com/thunderbird/thunderbolt)). We're an 8-person and growing team within the ~60-person company behind Thunderbird, the open-source email client used by 20M+ people. Thunderbolt is an open-source, cross-platform AI product built on the principle that people and organizations should be in control of their data, infrastructure, and model choices. It's moving from early development into enterprise use cases, and we need someone to own features end to end — concept through launch, adoption, and iteration — not just close tickets. You'd work full-stack on AI-powered chat, search, research, workflow automation, admin, and integrations. We're looking for 10+ years of engineering experience at Staff scope, hands-on AI product work (LLMs, RAG, agents, retrieval, model/provider abstraction), and comfort in ambiguity — architecture and enterprise requirements are still being defined. Bonus: self-hosted or regulated deployments, EU AI Act / GDPR / SOC 2 familiarity. Must reside in and have work authorization for the US or Canada. No sponsorship. We read every cover letter - please make it authentic.