Founding Engineer | AI-Native Ops Infrastructure (backed by Y Combinator, $3M+ ARR, $7M+ raised)

Legion Health (YC S21) is building the AI-native operations layer for mental health care.

We run our own psychiatric practice and are rebuilding what happens outside the visit—scheduling, intake, documentation, billing, risk detection, and coordination. Not “doctor-in-a-box,” but the operational backend that mental health actually runs on.

Our agent infrastructure already supports 2,000+ patients with one human support lead. The systems you build will land in real clinical workflows immediately.

Legion exists to make mental health care fast, affordable, and effective at scale—and this role is one of the highest-leverage ways to get there. By owning the infrastructure that turns clinical intent into reliable operations (and AI agents into trustworthy teammates), you’ll directly improve access, cost, and quality for thousands of patients while helping clinicians spend more time caring and less time fighting workflows.

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 bleeding-edge AI systems that make real workflows faster, safer, and more automated. Github: https://github.com/danielgwilson

I’m hiring a Founding Engineer to own core backend + agent systems end-to-end. You’ll help design and build the infrastructure that coordinates human clinicians, support staff, and AI agents like a single, coherent system.

Roles evolve quickly here—including mine. I’m looking for someone who wants to grow into owning major parts of the system, not someone depending on me to stay in a narrow CTO role forever.

• Own 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’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.

• Experience 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.

• Backend: Node.js, TypeScript, Supabase (Postgres), AWS (ECS, Lambda, S3)

• Frontend: Next.js 15 (App Router), Tailwind, Vercel

• AI: OpenAI, Anthropic, tool-calling agents, embeddings + vector DBs, Langfuse-style observability

• Other: PHI security, audit trails, real-time schedulers, transcript ingestion

• Apply here: https://jobs.ashbyhq.com/legionhealth/ffdd2b52-eb21-489e-b124-3c0804231424

• Overview of our hiring process:

  1. Systems/portfolio deep dive (45 min) – walk through 1–2 systems you’ve shipped; architecture, tradeoffs, failure modes.

  2. Practical work trial (1.5 hours) – short, realistic backend/LLM-systems exercise. No LeetCode, no puzzles.

  3. 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 days

• Start date: ASAP

• Job type: Full-time

• Role type: Engineering

• Ideal Experience Level: Doesn’t matter if you’re cracked

• US Visa Sponsorship: Yes

• Salary: $130,000–$190,000 (based on experience)

• Early-Stage Equity: 0.2%–0.8% meaningful early ownership

• Health Insurance: Medical, dental, and vision benefits

• Additional Perks: In-person retreats, meal stipends, etc.

• Time Off: Flexible, unlimited vacation policy

• Work Hours: Flexible but demanding because we're literally saving lives

• Work Setup: In-person @ San Francisco HQ

• Impact: 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.

Legion Health is proud to be an Equal Opportunity Employer. We celebrate diversity and are committed to creating an inclusive environment for all employees, contractors, and applicants without regard to race, color, religion, sex, sexual orientation, gender identity or expression, national origin, age, disability, veteran status, genetic information, or any other protected characteristic under applicable law. We encourage applicants from all backgrounds to apply.