Senior Software Engineer 5 — Validation & Safety Platform w Warszawa, Polska

Who you are

• Experienced building and operating a platform used by other engineering teams — you think about your product as a platform, not a one-off tool.
• Comfortable making product calls: what capability the platform should own, what it should expose as an API, and when to extend versus build new.
• An advanced user of agentic coding tools — you work daily with hooks, MCPs, and context management, even if you haven't built an agentic platform yourself.
• Security-minded: you have a working understanding of agent sandboxing, scoping, and redaction, even if it isn't your primary background.
• A strong communicator who can document technical tradeoffs clearly for both engineering and non-technical stakeholders.
• An advocate for a strong testing culture: familiar with test frameworks, code coverage tooling, CI systems, and post-deployment verification.

Experience we'd be excited about

• You have designed or operated developer-platform infrastructure: distribution, CI/CD, or versioning systems used by many teams.
• You have built or integrated LLM-based evaluation systems (LLM-as-judge, agent trajectory scoring, or similar).
• You have worked with mutation testing, static analysis, or test-selection systems at scale.
• You have hands-on experience sandboxing or scoping agent access to sensitive systems or data.

About the team

The Validation & Safety Platform is one of three pillars inside the new System Health, Validation & Insights Platform group in Productivity Engineering. Our mandate: catch safety and correctness regressions in human-written or agent-generated code before they reach production.

Netflix's agent fleet now writes, tests, refactors, and deploys code continuously across every domain. As agent volume grows, the constraint shifts from producing changes to knowing which ones are safe. Quality assurance can no longer be a human-gated step at the end of a PR — it has to be embedded at every stage of the developer loop, proactive and automated.

Today the team runs the validation and safety gates for the fleet: automated test generation, coverage and safeguards show teams where they stand. We're extending to other safety signals built specifically for agent-generated code, so we can judge whether a change is genuinely correct as agents write and modify code at scale.

About the role

We are looking for a Senior Software Engineer to help build the next generation of this platform: tools and guardrails that keep pace with an engineering org where a growing share of code is agent-generated.

You will design systems that thousands of engineers and their agents depend on, make build-vs-extend calls on what the platform should own versus expose through an API, and bring a security-conscious view to how autonomous agents get sandboxed, scoped, and safely given access to test infrastructure.

,[Design and build validation and safety products used platform-wide: test generation, coverage and safeguards, deterministic and predictive test selection, and mutation testing at scale., Build the polyglot static analysis layer that gives agent-generated code an automated, language-agnostic first quality gate., Develop agent-specific safety signals: detect prompt flakiness (an agent producing inconsistent output across identical prompts or seeds), evaluate agent trajectories against execution traces, and score semantic correctness of agent-generated code against the original requirement, the agent's own stated intent, and observed behavior change., Define clear platform capabilities and make deliberate build-vs-buy, build-vs-extend calls as the platform's scope grows., Apply sound judgment on agent sandboxing, scoping, and data redaction wherever the platform gives agents access to test infrastructure or execution environments.] Requirements: Java, Python, LLM, AI Agents, MCP, Testing, CI/CD, Spinnaker, Mutation Testing, Static Analysis, Agentic Evals, Distributed Tracing Additionally: Private medical package, Life insurance, Conferences, International environment, Work Not Drive, Employee Giving, Employee Assistance Program, Family Forming & Reproductive Health, PPK, Flexible working hours, In-house trainings, ESOP, Psychological support, Modern office building, Team events, Free lunch, Free parking, Mobile phone, Free snacks and beverages, Bike parking, No dress code, Shower, Free breakfast.