Principal Design Engineer

Position Summary

We’re building the next generation of intelligent, human-centered products that improve people’s health and well-being. We're looking for a Principal Design Engineer to own the bridge between design and code. Our design system serves web, iOS, and Android across every product and customer we support, which makes it the highest-leverage thing the design organization owns.

You'll own that system end to end: the component library, the theming architecture, the tooling that keeps design and code in sync, and the infrastructure that lets AI agents build with it correctly.

This is a senior individual contributor role. The work is infrastructure, so you'll be measured by what other designers and engineers can build because of what you built.

In this role, you will:

• Own and evolve the design system: component authoring, theming architecture, and parity between the design library and what ships in code.
• Own the tooling between design and code, including token pipelines, plugins, and automated checks that catch drift before people do.
• Build the infrastructure that lets AI agents use our design system correctly, including agent skills, reference documentation, and evals that measure whether the output holds up.
• Ship production code into the design system and the surfaces that consume it.
• Hold the cross-platform constraint across web, iOS, and Android, so one design decision serves all 3.
• Set the accessibility bar inside the system so teams inherit it by default.
• Own the open architectural questions about the system and drive each one to a decision.
• Document and teach your AI workflows so the whole design practice improves, not only your own output.
• Set the craft bar through what you ship, and build alignment with designers, engineers, and leads who don't report to you.

About You:

• 6+ years in a hybrid design/frontend role, frontend engineering, product design or design engineering,
• A portfolio of shipped work where you did both the design and the build. 
• You've authored a design system. We'll ask which decisions were yours, what you got wrong, and what you'd do differently.
• Strong design sensibility. You care about craft, consistency, and interaction quality, and you can articulate why a decision was right and what you traded away to get there.
• Fluent in both halves of the job: production React and TypeScript with real judgment about component API design, and Figma at authoring depth (variables, modes, component properties, design-to-code mapping).
• Daily, fluent use of Claude Code or equivalent, with hands-on experience writing agent skills, wiring up MCP servers, and benchmarking the results.
• You account for real-world complexity: edge cases, empty and error states, accessibility, and technical constraints. 
• High agency. You pick up unowned work, form a position, and drive it to a decision.
• Strong writing. Much of your output is documentation read by designers, engineers, and agents

Nice to Have

• Native iOS or Android experience.
• Tooling engineering in Node and TypeScript: CLIs, build scripts, token pipelines, CI automation.
• Server-driven UI development.
• Health tech or another regulated industry.
• Experience designing evals or otherwise benchmarking AI output quality.

Why you should join

• Own the system that every team and every product at League depends on.
• Work at the frontier of design systems built for AI agents, where most of the prior art doesn't exist yet.
• Set the technical direction for how design and engineering collaborate across 3 platforms.
• Partner with a talented, cross-disciplinary team of designers, engineers, and AI experts.
• Join a fast-growing company redefining the future of healthcare experiences.
• Be part of a supportive, forward-thinking design culture that values quality and experimentation.
• Competitive compensation, equity, and comprehensive benefits.
• Flexible vacation and time-off policy.
• Continuous learning and development support (courses, tools, reimbursements, etc.).

What we offer

• Comprehensive Health Benefits: We prioritize your well-being with complete medical, dental, and vision coverage
• Bonus Program: Be rewarded for your contributions with our performance-based bonus program
• Employee Stock Option Program: Become an owner and share in our success through our stock option program
• Unlimited Paid Time Off: Take the time you need to recharge and maintain a healthy work-life balance
• Spending Accounts: Manage your healthcare and dependent care expenses with tax-advantaged spending accounts
• Wellness Days: Prioritize your mental and physical health with dedicated wellness days throughout the year
• Growth Opportunities: We invest in your future with abundant opportunities for professional development and advancement
• Mentorship Program: Benefit from guidance and support from experienced leaders in your field
• Flexible Ways of Working: Enjoy the freedom to work in a way that suits your life and boosts your productivity

Security-Related Responsibilities:

• Compliance with Information Security Policies
• Compliance with League’s secure coding practice
• Responsibility and accountability for executing League's policies and procedures
• Notification of HR, Legal, Compliance & Security of any incidents, breaches or policy violations