Software Engineer (UI) - Agent-first Design Systems

We’re building a next-generation design system: semantic tokens, composable primitives, and product-grade patterns that scale across a suite of B2B SaaS experiences in the energy sector. The next step change is that AI agents will increasingly participate in the design and build of software and user interfaces.

This role helps define what “agent-ready” design systems look like while shipping world-class UX for humans today. Your goal is to make great UI repeatable at scale: build a token-driven foundation of primitives that grows into product-grade composites and patterns grounded in real needs while maintaining a high bar for visual craft, accessibility, and interaction quality. In parallel, you’ll help redefine the end-to-end design process for an agentic era: faster prototyping loops, tighter iteration cycles, and interaction-level refinement powered by automated AI workflows. We’re building the practical scaffolding that makes this scalable and reliable.

• Design tokens & theming: Own a token-first approach: semantic tokens that encode intent (not just values), multi-theme support, and predictable propagation into CSS variables and Tailwind mappings. Define conventions for naming, layering (core > semantic > component), and change management so teams can adopt incrementally. Ensure components consume tokens (not hard-coded styles) so overrides and theme changes behave reliably.
• Primitives & component architecture: Design and build highly reusable primitives and components with accessibility, state correctness, and interaction quality as default. Leverage headless UI foundations to ship production-ready components with crisp, maintainable APIs. Design systems around composition-first principles: small orthogonal building blocks, clear extension points, and patterns that avoid fragmentation (controlled/uncontrolled, slots/compound components, render props where appropriate).
• Composites & product patterns: Build and evolve product-oriented composites and patterns over time (tables, filters, dashboards, workflows), turning repeated needs into stable, documented patterns. Validate patterns against real constraints: data density, empty/error/loading states, performance, and responsive behaviour.
• Visual craft, motion & interaction: Apply deep CSS expertise to ship refined micro-interactions, transitions, and animations that communicate hierarchy, feedback, and affordance. Hold a high bar across variants and edge cases; improve quality without adding unnecessary complexity.
• Process, ops & agent readiness: Build the workflows that keep iteration fast: prototyping playbooks, tight feedback cycles, and repeatable ways to explore solutions, variants, states, and granular interactions without creating one-off debt. Define agent-legible representations of components/tokens/states and the guardrails needed for safe recomposition and generation. Create feedback loops so system changes (both human and agent-made) are observable, comparable, and trustworthy (docs, examples, internal tooling, regression checks).
• Collaboration & governance: Partner with product and engineering on adoption strategy, compatibility, deprecations, and migration paths. Help define standards for contribution, review, and release discipline; shape the culture and leverage of the design function as it grows.

Required attributes:

• Strong React/TypeScript fundamentals with proven experience building component libraries/design systems used across teams or products.
• Experience applying Tailwind CSS in scalable design systems using structured utility patterns, class composition and design tokens.
• Skilled at headless UI composition and component API design with accessibility baked in.
• High bar for visual quality and interaction design.
• Familiarity with agent coding tools (e.g. Claude Code, Codex, OpenCode) and emerging AI powered workflow patterns e.g. Spec Driven Development / Plan modes, parallelisation using worktrees, multi-agent orchestration, agents.md, skills etc.

Desirable attributes:

• Experience with data-heavy B2B interfaces and charting/theming systems.
• Internal tooling/CLI/platform experience.
• Experience with Rive.app.

A collaborative, mission-driven environment focused on transforming the global energy transition. A fun, informal, collaborative, and international work culture. A competitive salary package. Access to regular coaching and mentoring sessions, and the opportunity to learn from experienced professionals.

Some of the benefits we include are:

• Private Medical Insurance
• Dental Insurance
• Parental Support
• Salary-Exchange Pension
• Employee Assistance Programme (EAP)
• Local Oxford Discounts
• Cycle-to-work Scheme
• Flu Jabs

At AER, we are committed to offering flexibility in the way we work. Most of our roles are hybrid with a mix of in-office/home working and potentially adjustable working hours. Let’s discuss what works for you and AER during the interview process.

The Company is committed to the principle that no employee or job applicant shall receive unfavourable treatment on grounds of age, disability, gender reassignment, race, religion or belief, sex, sexual orientation, marriage or civil partnership, pregnancy, and maternity.

To apply, please submit your Résumé / CV, a personal summary, your salary expectations and please inform us of your notice period. Unfortunately, we are unable to accept applications via email, telephone, or social media platforms. To be considered for this position, please submit your application using the link provided. Applications submitted through any other channel will not be reviewed.