Principal Simulation Engineer (Modeling & Simulation)

About Code Metal Code Metal is the leader in automated software engineering you can trust. As AI writes more of the world's code, the bottleneck in software has shifted from writing code to verifying it works, and AI cannot verify its own work with certainty. Code Metal takes a fundamentally different approach: constrain AI to what it does reliably, verify every step independently of the model using formal methods, and keep engineers in the loop on the decisions that matter. The result isn't code that probably works — it's code that is provably correct, with auditable proof. Customers including the U.S. Air Force, L3Harris, RTX, and Toshiba use Code Metal to modernize legacy code, optimize performance on real hardware, and move prototypes to production, fast. Founded in 2023 with offices in Boston and San Francisco, Code Metal is funded by Accel, Salesforce Ventures, B Capital, Smith Point Capital, J2 Ventures, Shield Capital, Overmatch, RTX, and others. Learn more at codemetal.ai . About the Role: Our Modeling & Simulation team is building the next-generation wargaming and decision-support platform that helps the DoW make multi-billion-dollar force-design decisions before those decisions are made in the real world. The team spans simulation and physics, backend and data systems, frontend and geospatial visualization, and AI systems, working together to turn operational questions into extensible, mission- and campaign-level simulations that government users can trust. In this role, you'll develop simulation frameworks, platform and effects models, scenario infrastructure, and evaluation workflows that let defense users explore force-design choices before committing to them in the real world. This is a deeply hands-on software-engineering role — you'll spend most of your time designing, writing, reviewing, and shipping production C++ and Python. You'll own important parts of a cloud-distributed simulation environment and work directly with government users, leading through technical execution. Scope of ownership, architectural authority, and mentorship responsibility scale with level — see “Level Expectations by Track” below. What You’ll Do: Design and implement mission- and campaign-level simulation capabilities in modern C++ and Python. Build and extend event-driven, discrete-event, agent-based, and constructive simulation frameworks. Own core framework functionality, including event scheduling, simulation time, state transitions, platform abstractions, scenario execution, data collection, and deterministic replay. Develop models for platforms, sensors, weapons, communications, electronic warfare, jamming, command and control, logistics, and environmental effects. Extend AFSIM and comparable simulation environments through C++ plugins, framework services, SDK integrations, new platform types, and reusable model interfaces. Translate operational concepts, system specifications, and subject-matter expertise into maintainable software models with explicit assumptions and testable behavior. Modernize legacy campaign and mission-analysis tools and integrate them into a coherent simulation architecture. Build scenario-generation, Monte Carlo, sensitivity-analysis, campaign-execution, and evaluation workflows. Scale simulations across developer workstations, on-premises infrastructure, and cloud compute while preserving reproducibility and model provenance. Connect constructive simulations with distributed, operational, hardware-in-the-loop, or human-in-the-loop environments where appropriate. Establish verification and validation practices, reference scenarios, regression suites, and quantitative measures of model credibility. Work directly with government, Air Force, and broader DoD stakeholders to understand acquisition questions and deliver usable capabilities quickly. Collaborate with physics, backend, geospatial, AI, and product teams to integrate the simulation kernel into a larger interactive platform. Lead design and code reviews, mentor teammates, and improve architecture, documentation, testing, and release practices. What We’re Looking For: Required Qualifications The following apply to this role at every level. Years of experience, scope of ownership, and architectural/mentorship expectations scale by level — see “Level Expectations by Track” below. Five or more years of professional software-development experience building simulation, autonomy, robotics, game-engine, digital-twin, or similarly complex systems. Strong production experience in modern C++, with proficiency in Python for tooling, orchestration, analysis, or automation. Hands-on experience developing or extending a simulation framework — not only configuring simulation tools or analyzing their output. Experience with event-driven, discrete-event, agent-based, constructive, or distributed simulation architectures. Demonstrated ability to represent complex real-world entities, interactions, rules, and edge cases as clear software abstractions. Experience building plugins, SDKs, reusable model interfaces, framework services, platform types, or similar extension mechanisms. Strong understanding of software architecture, data structures, algorithms, APIs, testing, debugging, and performance engineering. Experience making substantial changes within a large existing codebase while maintaining ongoing delivery. Experience with model verification, validation, calibration, or regression testing. Ability to turn ambiguous operational or technical requirements into executable engineering plans. Strong written and verbal communication skills, including the ability to document model assumptions, limitations, interfaces, and intended use. Bachelor's degree or equivalent experience in computer science, engineering, applied mathematics, operations research, physics, or a related discipline. Active Secret clearance or eligibility to obtain one. Strongly Preferred: Direct experience developing AFSIM plugins, framework extensions, event infrastructure, or custom platform types. Experience with behavior trees, finite state machines, and planning languages (e.g., PDDL) in the context of mission planning and behavior modeling Experience supporting Air Force, Space Force, joint, or broader DoD acquisition and mission-analysis programs. Experience developing models for sensors, weapons, electronic warfare, jamming, communications, logistics, or command and control. Experience translating or modernizing a large legacy modeling or campaign-analysis system into C++. Experience designing a simulation framework, event stack, plugin architecture, or campaign system from the ground up. Familiarity with HLA, DIS, OneSAF, JSAF, NGTS, STK, or other constructive and distributed simulation environments. Experience spanning both operational and constructive simulation. Active TS/SCI clearance. Principal Level Expectations Years of Experience: 10+ Engineering Craft & Code Quality: Sets the quality and correctness bar across the department; their work is the example others learn from; improves the automated systems and practices that ensure quality department-wide. Architecture & Technical Knowledge: Provides architectural guidance across the department and invents paradigms that solve CodeMetal-specific domain problems (e.g., translation, optimization, deployment across target environments); a key resource on every major system. Delivery, Scoping & De-risking: A consistent contributor to the company's technical roadmap; gives reliable estimates for large cross-team initiatives; ensures pragmatic scoping toward the most valuable outcomes. Technical Leadership & Mentorship: An active driver of company-wide architectural reviews and proposals; mentors mid-level and senior staff at scale; influences others across departments toward the best technical outcome. Benefits Pay depends on experience, but we strive to be at the upper end of the salary range Health care plan with 100% premium coverage, including medical, dental, and vision 401k with 5% matching Paid Time Off (uncapped vacation, plus sick and public holidays) Flexible hybrid or remote work arrangement Relocation assistance for qualifying employees Wage Transparency - The salary range for this role is not a guarantee of compensation or salary, as the final offer amount may vary based on factors including, but not limited to, individual proficiency, skills, experience, and location. We are an equal opportunity employer. US Citizenship may be required for certain project assignments involving security clearance. Pursuant to the San Francisco Fair Chance Ordinance, we will consider for employment qualified applicants with arrest and conviction records.