Frontend Engineer, Core Platform

Lumbra•Arlington, VA

3d•Onsite

About The Position

Lumbra is hiring a Frontend Engineer for its Core Platform team to own and build the interface for Nebula, its agentic harness. The interface must make agents’ work legible as it streams, show sources and reasoning, and help analysts navigate dense, connected data under pressure. The application must perform reliably in both commercial cloud and disconnected, classified environments. This is an on-site role in Arlington, Virginia; remote and hybrid work are not available. The role is structured around approximately 70% product development in React and TypeScript, 20% quality and performance work, and 10% collaboration with users and product partners. The engineer will build conversation, workflow, and graph interfaces; establish front-end architecture and shared design-system components; and ensure performance, accessibility, testing, and offline operation. The role works with Forward Deployed Engineers and analysts to translate field feedback into interface improvements. The position is focused on the front end, though it involves reading and shaping backend API contracts. It is not limited to implementing mockups: the engineer will help shape the product experience and will be responsible for front-end performance. The role offers the opportunity to work alongside government officers, engineers, veterans, and applied AI engineers, and to own part of an early-stage company. The role spans Engineer II and Senior Engineer levels, with compensation based on scope, autonomy, and technical capability.

Requirements

Real depth shipping production front-end software in React and TypeScript; meaningful ownership of front-end systems is valued over a specific year count. 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 experience with component design, state management, and render performance, 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 loose 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 accessibility (WCAG) 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 production product features in React and TypeScript, including conversation interfaces, workflow views, and graph views.
Build conversation and streaming interfaces for agent output, including tool calls, citations, confidence, and long-running work that can recover 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 can withstand frequent change.
Build and maintain shared components and the design system in code.
Measure and improve performance and accessibility; profile performance issues and address slowness as a defect.
Write component, integration, and end-to-end tests that cover the specification.
Ensure builds work in disconnected, air-gapped deployments without relying on external CDNs, fonts, or services.
Work with Forward Deployed Engineers and analysts to turn field feedback into interface changes.
Turn loosely defined requests into working interfaces without requiring finished designs.

Benefits

Health, dental, and vision insurance, with 99% of employee premiums and 100% of dependent premiums covered.
Optional HSA plan that is lower premium, HSA eligible, fully 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.
Fully covered Wellhub Gold membership, including access to gyms and studios.
Unlimited PTO.
Every federal holiday and additional paid days off over winter break.
Supportive leave of absence program, including time off for military service, medical events, and parental leave.
Breakfast, lunch, and snacks in the office.
Pre-tax commuter benefits.
Company-paid phone plan and iPhone.
Equity as part of total compensation.