Frontend Engineer, Core Platform

Lumbra • Arlington, VA

4d • $120,000 - $300,000 • Onsite

About The Position

Lumbra is hiring a Frontend Engineer for its Core Platform to own the interface for Nebula, its agentic harness. The role builds the React and TypeScript application analysts use to review agent work, sources, reasoning, and dense connected data. The interface must be fast, legible, and reliable in both commercial cloud and disconnected, classified environments.

The work is structured as approximately 70% product development, 20% quality and performance, and 10% user and product collaboration. The engineer will build conversation and streaming interfaces, workflow and knowledge-graph views, front-end architecture, shared components and design-system patterns, and automated tests. The role also focuses on profiling and improving performance, accessibility, and ensuring builds run without external dependencies in air-gapped deployments.

This is an on-site position in Arlington, Virginia; remote and hybrid work are not available. The role spans Engineer II and Senior Engineer levels. Base salary is $120,000 to $300,000, with placement based on scope, autonomy, and technical capability. Base salary is one part of total compensation, alongside equity and benefits.

Requirements

• Production front-end experience with substantial depth in React and TypeScript; engineers with 2+ years who have owned meaningful front-end systems are welcome.
• Experience building interfaces for real-time or streaming data, such as WebSockets or server-sent events, including the underlying state model.
• Strong component-design, state-management, and render-performance experience, including examples of profiling and fixing problems.
• Ability to write clean, well-tested code, including component and end-to-end tests.
• Enough backend fluency to read and shape API contracts.
• Comfort turning a loosely defined request into a working interface without a finished design.
• A humble, hands-on approach.
• Willingness to work on site in Arlington, Virginia.

Nice To Haves

• Python experience.
• Experience building LLM or agent interfaces, including streaming output, tool-call visualization, and citation surfacing.
• Experience with data-visualization or graph-exploration libraries.
• Experience building or maintaining a design system.
• Experience with WCAG accessibility in complex applications.
• Experience building analytical, intelligence, financial, or developer-facing tools.
• Experience shipping front ends into restricted or offline environments.
• An active U.S. security clearance or eligibility to obtain one.

Responsibilities

• Build product features in React and TypeScript, including conversation interfaces, workflow views, and graph views.
• Develop conversation and streaming interfaces for agent output, including tool calls, citations, confidence, and long-running work that recovers from timeouts and reconnects.
• Create workflow and knowledge-graph visualizations that keep dense analytical data legible.
• Own front-end architecture, including state management, data fetching, backend API contracts, and patterns that accommodate change.
• Build shared components and design-system patterns that make features consistent.
• Measure and improve performance and accessibility; profile issues rather than guessing and treat slowness as a defect.
• Write component, integration, and end-to-end tests that cover the specification.
• Ensure builds work on disconnected networks without reliance on external CDNs, fonts, or services.
• Work with Forward Deployed Engineers and analysts to turn field feedback into interface changes.
• Read and shape API contracts with backend partners.

Benefits

• Health, dental, and vision insurance, with 99% of employee premiums and 100% of dependents' premiums covered.
• Optional HSA plan that is lower-premium, HSA-eligible, portable, and self-directed or managed.
• Health Reimbursement Account for qualified healthcare expenses.
• Company-paid $150,000 life insurance plus AD&D.
• 401(k) with a 100% match on the first 6%, immediately vested with no cliff or waiting period.
• Wellhub Gold membership, including access to gyms and studios.
• Unlimited PTO.
• Federal holidays and additional paid days off over the winter break.
• Supportive leave-of-absence program, including time off for military service, medical events, and parental leave.
• Breakfast, lunch, and snacks at the office.
• Pre-tax commuter benefits.
• Company-paid phone plan and new iPhone.
• Equity.

What This Job Offers

• Job Type: Full-time
• Career Level: Mid Level
• Education Level: No Education Listed