Founding Engineer | AI-Native Mental Health Care (backed by Y Combinator, $3.3M+ ARR, $7M+ raised)

About Legion HealthLegion Health (backed by Y Combinator) is building autonomous mental healthcare-AI that takes real responsibility across the full care loop: before the visit, during the visit, and after the visit.We run our own psychiatric practice, which means we ship into reality-not theory. We're rebuilding the patient experience end-to-end:Outside the visit: scheduling, intake, benefits checks, paperwork, reminders, care coordination, billing, risk detection, follow-ups, and patient messagingInside the visit: visit support, real-time note scaffolding, structured history capture, differential reasoning support, diagnostic signal extraction, treatment planning assistance, medication decision support, and clinician workflows that make great care feel effortlessNot "doctor-in-a-box." Not a layer of prompts. We're building AI teammates that clinicians can trust-agents that do the work, show their reasoning, handle edge cases, and escalate cleanly when humans need to step in.Our agent system already supports 2,200+ patients with a tiny team. The systems you build go straight into production and show up in patient outcomes, clinician velocity, and the quality of care-immediately.Legion exists to make mental healthcare fast, affordable, and excellent at scale. This role is one of the highest-leverage ways to get there: you'll help turn clinical judgment into reliable systems, and turn AI from a tool into a true operator-so patients get sharper care and clinicians get their time back.Role: Founding Engineer - AI-Native Mental Health Care (In-Person in SF)Hey-I'm Daniel Wilson, co-founder & CTO at Legion. I studied applied math + CS at Princeton, then led the Office Scripts + Power Automate integration at Microsoft-shipping the highest retention-driving feature in the product. Before that, I did deep learning + RL research. I'm obsessed with building AI systems that make real workflows cleaner, safer, and more autonomous. Github: https://github.com/danielgwilsonI'm hiring a Founding Engineer to own core product + agent systems end-to-end. You'll build the layer that coordinates patients, clinicians, and AI agents as one coherent machine-tight feedback loops, high standards, and real ownership.This isn't "just infra." It's building the product heart of an autonomous care system: the workflows, the agent behaviors, the guardrails, the integrations, the UX that makes it usable, and the reliability that makes it trusted.Roles evolve quickly here-including mine. I'm looking for someone who wants to carry real weight, take full ownership, and grow into running major parts of the system-not someone who needs a perfectly scoped box to operate inside.• What You'll DoOwn our event-driven backend - Architect and scale our Node.js / TypeScript / Supabase (Postgres) / AWS stack. Design schemas, invariants, and workflows that encode how psychiatric care actually operates. Turn messy real-world processes into clean state machines and event streams.Build real LLM agents as coworkers - Implement tool use, retries, memory, and safety rails. Design action schemas and evaluation loops so agents can run reliably in production. Work on orchestration, context management, and multi-step workflows.Shape human + AI ops UX - Build internal tools used by both humans and agents. Make it trivial to see "what happened, why, and what should happen next" in any patient journey.Define world-state & simulation - Model the canonical state of a patient's journey across time. Power alerting, routing, and decision-making from that live simulation.Own data, safety & compliance - Engineer HIPAA-compliant pipelines for transcripts, events, and EHR data. Ensure PHI access, agent actions, and human overrides are all auditable.Drive architecture & strategy - Work directly with me to debate tradeoffs, define new primitives, and decide what we build next.You don't need to be a pure backend engineer-we value great product engineers who can learn fast, make strong simplifying decisions, and grow into owning backend/agent systems.You Might be a Fit If...You've owned real systems 0→1 or 1→N, not just tickets.You think in events, state, and invariants, not just CRUD endpoints.You're either already LLM-fluent or a strong systems/backend engineer who can get dangerous fast.You care about velocity and correctness-moving quickly while keeping things understandable and robust.You like small, high-candor teams and direct feedback.You want to see your work go live in production weekly, not sit on a roadmap.Nice to HaveExperience with Node.js / TypeScript, Postgres, or Supabase.Experience with LLMs, agents, tool-calling, or RAG.Experience in healthcare, fintech, or other regulated / high-stakes domains.Experience in early-stage startups or founding teams.Our Tech StackBackend: Node.js, TypeScript, Supabase (Postgres), AWS (ECS, Lambda, S3)Frontend: Next.js 15 (App Router), Tailwind, VercelAI: OpenAI, Anthropic, tool-calling agents, embeddings + vector DBs, Langfuse-style observabilityOther: PHI security, audit trails, real-time schedulers, transcript ingestionHow to Apply and Hiring ProcessApply here: https://jobs.ashbyhq.com/legionhealth/ffdd2b52-eb21-489e-b124-3c0804231424Overview of our hiring process:Systems/portfolio deep dive (45 min) - walk through 1-2 systems you've shipped; architecture, tradeoffs, failure modes.Practical work trial (1.5 hours) - short, realistic backend/LLM-systems exercise. No LeetCode, no puzzles.Final onsite (1.5 hours) - meet the team, pair on a real issue, and talk through how you'd own a domain.Estimated time-to-hire: 7-10 daysStart date: ASAPRole Logistics, Compensation, and BenefitsJob type: Full-timeRole type: EngineeringIdeal Experience Level: Doesn't matter if you're crackedUS Visa Sponsorship: YesSalary: CompetitiveEarly-Stage Equity: 0.2%-0.8% meaningful early ownershipHealth Insurance: Medical, dental, and vision benefitsAdditional Perks: In-person retreats, meal stipends, etc.Time Off: Flexible, unlimited vacation policyWork Hours: Flexible but demanding because we're literally saving livesWork Setup: In-person @ San Francisco HQImpact: Work on something that truly matters to millions of patients and families.Autonomy and Learning: Ownership over your projects with the freedom to set priorities, shape processes, and drive outcomes end-to-end.Growth Opportunities: As we scale, we envision our top performers from our founding team stepping into expanded roles and joining our executive leadership team.Equal Employment Opportunity