Senior Fullstack Engineer, Replay

Lyric is an AI-first, platform-based healthcare technology company committed to simplifying healthcare payment integrity. The Senior Fullstack Engineer will be responsible for modernizing the payment integrity platform, building scalable web experiences, and utilizing AI tools to enhance productivity and quality in the software development process.

Responsibilities:

• Use AI agents (Cursor, Claude Code, Codex) to blow through framework upgrades, refactors, API extraction, test scaffolding, and documentation - while catching hallucinations and preventing regressions before they hit a PR
• Build reusable playbooks the team can actually follow: prompt templates, repo-level agent instructions, migration checklists, review heuristics, and clear 'definition of done' standards for AI-assisted changes
• Upgrade legacy services to current .NET (LTS where it makes sense), untangling architecture boundaries and fixing the performance issues that have been 'known' for years
• Push toward a proper API-layer architecture - RESTful, versioned - built for correctness and maintainability, not just 'it works.'
• Get your hands dirty with SQL Server: query performance, indexing, transactional correctness. If there are data pipeline needs (Kafka, etc.), you'll help build those too
• Build with security and privacy as defaults, not afterthoughts. Least privilege, safe data handling, the works. This is healthcare - getting it wrong isn't an option
• Put real quality guardrails in place: automated tests that actually catch things, CI that blocks bad changes, structured logging, observability that tells you what's happening before users do
• Review code thoughtfully, have honest architectural conversations, and raise the bar without being a jerk about it
• Partner with analysts, stakeholders, and other engineers to turn business problems into working software - not just technically correct software, but software that actually solves the problem
• Help build delivery plans that are honest about trade-offs. 'Right' vs. 'right now' is a real tension - you'll help the team navigate it with pragmatic milestones

Requirements:

• 5+ years building and shipping production systems. Not side projects - real software with real users solving skills; able to work independently and collaboratively in fastmoving teams
• Some C# and modern .NET experience (Core and beyond). Especially in large codebases and you've done meaningful refactoring and migration work, not just greenfield
• Strong SQL Server chops - schema design, query tuning, performance troubleshooting. You've worked on data-heavy applications where the database wasn't an afterthought
• Cloud experience with Azure and/or AWS. Azure is particularly relevant here
• API design experience - you've built and maintained service-oriented architectures with real versioning, auth, reliability, and testing practices
• You actually use AI coding tools as a daily driver. Cursor, Claude Code, Codex, or similar - and not just for autocomplete. You've used agents for multi-file refactors, migrations, test generation, and review workflows. You have opinions about what works and what doesn't
• You communicate clearly. Good PR descriptions, straightforward design docs, pragmatic collaboration, low ego. We don't need a rockstar - we need someone the team trusts
• You've actually done a legacy ASP.NET / .NET Framework modernization before. You know where the bodies are buried and you have the scars to prove it. Bonus points for Azure modernization patterns
• Experience with distributed systems tooling - Kafka, event-driven architectures, or working with Postgres alongside SQL Server
• Front-end experience with Angular and/or React/Next.js
• You've helped establish agent-friendly engineering practices: writing repo instructions that AI tools can follow, breaking work into agent-sized tasks, setting up CI guardrails for AI-generated code, feature flags, canary deployments - any part of the progressive delivery toolkit
• Background in regulated domains (healthcare, fintech, payments) where 'move fast and break things' will get you fired