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Senior UI Engineer (React & Design Systems - Fixed-Term Contract) Role Overview We are seeking an experienced, high-impact Senior UI Engineer to join our established Agile Scrum team for a 6-month fixed-term engagement. In this role, you will build, extend, and harden our next-generation Building Automation System (BAS) shared UI framework—the component, theming, state, and API-access layer deployed across both edge/on-premises and cloud-hosted environments. This is a fast-paced development contract where you will collaborate directly with permanent engineers to deliver critical feature surfaces, optimize front-end performance, ensure cross-target correctness, and leave behind pristine documentation and test coverage. If you possess deep expertise in React and design systems, we want to hear from you. Key Responsibilities Framework & Feature Development

• Component Engineering:

  Build, extend, and harden reusable React and TypeScript components within our design system, covering states, theming/tokens, keyboard interactions, and accessibility compliance.

• Feature Surfaces:

  Implement assigned BAS UI screens and workflows against defined UX designs and REST/streaming APIs, ensuring robust data fetching, caching, and offline/degraded-connectivity handling.

• Cross-Target Correctness:

  Ensure seamless UI execution across both edge/on-premises and cloud-hosted deployments on supported screen sizes and browsers.

• Defect Triage & Burn-Down:

  Take assigned defects from triage to verified fix, complete with root-cause documentation. Testing, Performance & Handover

• Test Coverage:

  Write and maintain comprehensive unit and component tests (Jest/Vitest + React Testing Library) alongside automated end-to-end flow coverage.

• Performance Optimization:

  Diagnose and resolve front-end bottlenecks, including bundle size, render cost, large data-set virtualization, and memory retention in long-running sessions.

• Documentation & Handover:

  Leave behind clear component documentation, usage examples, and architecture decision notes to empower the permanent team post-engagement. Qualifications & Requirements Minimum Qualifications

• Education & Experience:

  Bachelor's degree in Computer Science, Software Engineering, or equivalent demonstrated professional front-end engineering experience (4+ years building production web applications).

•

Technical Mastery:

oDeep, current expertise in TypeScript and React (hooks, component composition, state management, and rendering behavior). oFluent modern HTML and CSS (responsive layouts, theming, CSS modules / CSS-in-JS). oProven experience building or extending a reusable component library or design system consumed across multiple applications. oStrong debugging and performance profiling skills using browser developer tools.

• Workflow & Agile Habits:

  Active practitioner of CI/CD workflows (small pull requests, automated testing, short-lived branches, rigorous code review); reliable estimator and active contributor to Agile ceremonies (sprint planning, daily standups, retrospectives).

Environment:

Comfortable developing across both Windows and Linux environments. Preferred Attributes

• Accessibility implementation experience adhering to

WCAG 2.1 AA

standards (ARIA patterns, keyboard-only navigation).

• Familiarity with Node.js/BFF or .NET/C# back-end environments to facilitate cross-boundary debugging; Angular experience is also a plus.
• Experience building real-time or high-frequency data UIs (WebSockets/SSE, virtualized tables, time-series charting).
• Background in building automation, industrial control, IoT, SCADA, or operational technology (OT) domains. Engagement Details & Next Steps

• Duration:

  6-Month fixed-term contract engagement.

•

Team Model:

Integrated directly into an active 3-week sprint Agile team. Ramps up quickly with a first reviewed pull request merged within the opening sprint. Equal Opportunity Employer / Disabled / Protected Veterans The Know Your Rights poster is available here: https://www.eeoc.gov/sites/default/files/2023-06/22-088_EEOC_KnowYourRights6.12.pdf The pay transparency policy is available here: https://www.dol.gov/sites/dolgov/files/ofccp/pdf/pay-transp_%20English_formattedESQA508c.pdf For temporary assignments lasting 13 weeks or longer, AllSTEM Connections is pleased to offer major medical, dental, vision, 401k and any statutory sick pay where required. We are committed to working with and providing reasonable accommodations to individuals with disabilities. If you need a reasonable accommodation for any part of the employment process, please contact your staffing representative who will reach out to our HR team. AllSTEM Connections participates in the E-Verify program in certain locations as required by law. Learn more about the E-Verify program.

https:

//e-verify.uscis.gov/web/media/resourcesContents/E-Verify_Participation_Poster_ES.pdf We also consider for employment qualified applicants regardless of criminal histories, consistent with legal requirements, including, if applicable, the City of Los Angeles' Fair Chance Initiative for Hiring Ordinance. Pursuant to applicable state and municipal Fair Chance Laws and Ordinances, we will consider for employment-qualified applicants with arrest and conviction records, including, if applicable, the San Francisco Fair Chance Ordinance. For Los Angeles, CA applicants: Qualified applications with arrest or conviction records will be considered for employment in accordance with the Los Angeles County Fair Chance Ordinance for Employers and the California Fair Chance Act.