Full-Stack Engineer, Agentic Development

Expression•Washington, DC

About The Position

Expression is seeking a Full Stack Engineer to develop and deliver software across federal mission systems, using AI coding agents as a primary development tool. The role spans web interfaces, backend services and APIs, databases, and the containers and pipelines used to deploy applications to AWS. The engineer directs agents such as Claude Code, OpenAI Codex, and Factory’s Droids while owning planning, technical decisions, code review, testing, and the quality of every change. They also use AI to explore unfamiliar codebases, evaluate technologies, and develop proofs of concept. The role requires strong software engineering fundamentals, practical experience using AI agents, the ability to identify and correct flawed or insecure generated code, and the ability to work independently when AI tools are unavailable. The engineer collaborates with senior engineers, technical leads, product owners, and end users, owning clearly scoped features from planning through deployment and potentially taking on broader design responsibilities over time. A Secret clearance or higher eligibility is required. The position is hybrid in the DMV or remote, with onsite work at Expression headquarters and client sites as needed. Remote employees should expect travel a few times per year. Expression provides data fusion, data analytics, AI/ML, software engineering, information technology, and electromagnetic spectrum management solutions to the U.S. Department of Defense, Department of State, and national security community. Its culture emphasizes agile delivery, sustained client engagement, professional growth, and a collaborative environment.

Requirements

Bachelor’s degree in Computer Science, Software Engineering, Information Technology, or a related field, or equivalent professional experience.
At least three years of professional software engineering experience.
Strong programming skills in JavaScript, TypeScript, and Python.
Hands-on experience developing web interfaces using React or a similar framework and backend services or REST APIs using Node.js, Python, or similar technologies.
Strong understanding of browsers, HTTP, REST APIs, and authentication.
Strong understanding of relational data modeling and SQL.
Strong understanding of core data structures and algorithms.
Strong understanding of software testing and debugging.
Strong understanding of common application security risks, including the OWASP Top 10.
Strong understanding of Linux command-line tools, Bash scripting, and Git.
Hands-on experience with MongoDB or a similar document database, including document schema design, queries, aggregations, and index selection.
Hands-on Docker experience, including writing Dockerfiles, troubleshooting image builds, and running multi-container applications with Docker Compose.
Experience building or modifying CI/CD pipelines using GitLab CI, GitHub Actions, or similar platforms.
Hands-on experience deploying applications to AWS using services such as EC2, S3, and RDS, with a working understanding of IAM and VPC networking.
Regular, hands-on use of AI coding agents such as Claude Code, OpenAI Codex, Factory’s Droids, or similar tools for most implementation work. Experience must include directing agents that read code, run commands, and make changes, with independent verification through testing, code review, and comparison against requirements. Personal and open-source projects qualify; autocomplete-only experience does not meet this requirement.
Experience with Elasticsearch, including index mappings, search queries, and aggregations.
Experience with PostgreSQL.
Experience using Python for ETL, data pipelines, or migrations, including validation and reconciliation of results.
Experience using AI for technical research, evaluation, or proofs of concept, such as exploring an unfamiliar codebase, comparing libraries, or prototyping a proposed solution.
Demonstrated initiative through independently identifying problems, proposing improvements, and delivering solutions.
Clear written communication skills, including the ability to prepare precise instructions, explain technical decisions, and present recommendations.
Ability to develop, troubleshoot, and maintain software when AI tools are unavailable.
Eligible for Secret clearance or higher.

Nice To Haves

Experience developing agent instructions, prompts, or reusable skills, including CLAUDE.md or AGENTS.md files, custom commands, or Model Context Protocol (MCP) servers.
Experience preparing design documents or technical proposals and guiding them through review.
Experience configuring AWS infrastructure, including IAM policies and VPC networks.
Experience with infrastructure as code tools such as Terraform or CloudFormation, or with AWS GovCloud.
Experience with Playwright or another end-to-end testing framework.
Experience with Keycloak or another identity and access management platform.
Experience with additional languages or frameworks, such as Java, Angular, or PySpark.
Experience working in air-gapped or other restricted environments.
Experience supporting Department of Defense or other federal customers, including STIG requirements and classification marking requirements.

Responsibilities

Develop features across the application stack, including React interfaces, Node.js and Python services, REST APIs, and relational and MongoDB data models.
Own assigned features from requirements clarification and implementation through testing, deployment, and documentation.
Write and maintain unit, integration, and end-to-end tests.
Troubleshoot issues across application layers, identify root causes, and implement fixes with tests or monitoring to prevent recurrence.
Direct AI coding agents through clear task descriptions, implementation plans, and acceptance criteria.
Review, test, and correct agent-generated code to ensure it meets functional, security, maintainability, and performance requirements.
Use AI to research unfamiliar code, libraries, and services; compare technical approaches; and document recommendations and tradeoffs.
Develop proofs of concept to validate ideas and reduce design risk, then mature approved approaches into production software with appropriate tests, CI/CD, and documentation.
Help maintain agent instructions, prompts, and reusable skills to improve the team’s development practices.
Package applications using Docker and build and maintain CI/CD pipelines that test, scan, and deploy software.
Deploy and support services on AWS, coordinating infrastructure and security changes with senior engineers.
Contribute to security hardening and Security Technical Implementation Guide (STIG) evidence.
Maintain documentation that enables other engineers and their AI tools to understand, operate, and support the software.
Collaborate with engineers, technical leads, product owners, and end users to clarify needs and deliver practical solutions.
Proactively identify issues such as unreliable tests, slow application performance, manual processes, and documentation gaps.
Propose improvements, communicate their value and tradeoffs, and carry approved changes through completion.