Senior / Staff Forward Deployed Software Engineer - TS/SCI Cleared

ABOUT THE COMPANY America is under sustained cyber attack. Our adversaries infiltrate our networks, steal our IP, and degrade the digital infrastructure that modern life runs on. They’ve learned—correctly—that those attacks rarely produce consequences. Twenty was founded to change that, by making our adversaries think twice before they attack us. Our vision is American and allied primacy in cyberspace—a future where they cannot contest us, deterrence is assured, and the free world remains secure. Founded in 2024, Twenty Technologies (www.twenty.io http://www.twenty.io) industrializes offensive cyber operations for the U.S. and its allies. Headquartered in Arlington, Virginia, Twenty has raised $168M from Khosla Ventures, Accel, Caffeinated Capital, Friends & Family Capital, Point72 Ventures, General Catalyst, and In-Q-Tel. Mission | On Site | Full Time | Active TS/SCI with Full Scope Polygraph OR Active TS/SCI with CI Polygraph ROLE SUMMARY You'll be on the ground at a government customer site, serving as a generalist engineering presence for Twenty's mission-critical platform in a restricted, air-gapped environment. Twenty builds software for cyber operations, and the applications you'll extend and operate are used by operators and analysts working against hard national security problems. This is the broadest engineering role at Twenty. In a given month you might build a customer-specific feature, integrate a new data source, get an extension through the customer's deployment process, chase down a production failure, tune the monitoring that would have caught it sooner, and prototype an AI-backed capability with support from Arlington. You won't be an expert in all of it, and the role isn't designed to require that. For specialist work like data engineering and AI engineering, you'll deliver with guidance from the Arlington engineers who specialize in it. What the role does require is range: the ability to pick up an unfamiliar part of the system, get productive quickly, and produce work that holds up in production. The office-based team can't access this environment, so you are the engineering presence where the software actually runs. Problems reach you first, and the judgment calls are yours: what's wrong, what's urgent, and what Arlington needs to know. When customer work is quiet, you'll build features for Twenty's core product applications, carrying what you learned in the field directly into the product. You'll report directly to the VP of Engineering. You'll be part of a small forward deployed team, working closely with other on-site colleagues, the Arlington-based product engineering and DevSecOps teams, and the customer's own technical staff. If you're a strong generalist who wants your work in the hands of operators the same day you build it, and you'd rather own a production system end to end than ship features into a backlog, this role is for you. WHAT YOU'LL DO CUSTOMER-SPECIFIC FEATURES & EXTENSIONS - Design and build features, extensions, and integrations that adapt Twenty's applications to this customer's mission, workflows, and environment. - Work directly with customer users and technical staff to understand what they actually need, then scope and deliver it, making pragmatic trade-offs between speed, robustness, and what the environment allows. - Write code that is testable, debuggable, and maintainable by engineers who can't access the environment in which it runs. Tests carry unusual weight here: they're how Arlington trusts a change they'll never see run. - Write code that meets the security standards of classified environments: no hardcoded secrets, disciplined credential handling, and audit-ready practices throughout, so your work moves through the customer's approval process without friction. DATA INTEGRATION & AI-BACKED CAPABILITIES - Build software extensions that retrieve, parse, transform, and load new data sources into Twenty's applications, working with forward deployed data engineers where present and Arlington data engineers where not. - Investigate unfamiliar source systems and data formats, working with customer stakeholders to understand semantics, access patterns, and constraints before writing code. - Extend and field-test AI-backed capabilities in Twenty's applications with guidance from Arlington AI engineers, and report back what actually works against real data and real users. DEPLOYMENT & SITE RELIABILITY - Work with the customer's deployment team to get software approved, deployed, and running in the high-side environment, and execute deployments and updates in coordination with Arlington engineering. - Monitor the health of the platform and its data flows on-site using the LGTM stack (Grafana, Loki, Tempo, Mimir); identify anomalies and degradations before they become incidents. In an air-gapped environment, efficiency compounds. - Diagnose and resolve production issues where they happen, escalating to Arlington with a clear picture of what you found, not just what triggered the alert. - Drive root cause analysis and post-incident reviews in partnership with the Arlington engineering team, and turn findings into runbooks, fixes, or upstream design changes. - Participate in on-call rotation using PagerDuty, with clear escalation paths to the engineering team. The environment is air-gapped, so off-hours incident response may require returning to the customer facility rather than remoting in. PRODUCT ENGINEERING - When customer-driven work is quiet, build feature capabilities for Twenty's core product applications alongside the Arlington product engineering teams. - Surface patterns from the field that should become platform capabilities, and advocate for them with the product engineering team. What you generalize from one customer makes every deployment after it faster. CUSTOMER & TEAM LIAISON - Serve as a consistent engineering presence for the government customer: professional, reliable, and clear under pressur