Senior Full - Stack / Infra Engineer

Responsibilities:

• Run MicoAI in production: Own monitoring, dashboards, and alerts that actually fire; on-call runbooks; rollback; and incident follow-up with root-cause analysis.
• Track and control cost: Make AWS and model (token) costs visible per environment and per successful outcome, and set budgets and alerts before usage grows.
• Build the platform as code: Evolve our Terraform for ECS Fargate, Aurora MySQL, Valkey, load balancing, and private networking, and our CI/CD with build-once, promote-to-production releases.
• Harden security: Close security findings, tune edge protection and security alerting, and manage secrets and access with least privilege.
• Ship features end-to-end: Build across the TypeScript backend and the React web app, for example, making writes to the marketing platform more reliable or improving the review experience.
• Make the agent runtime dependable: Long-running and resumable agent runs, sessions, and deploys that don't interrupt users.
• Raise the bar: Most code is written with AI tools; review it with tests as the gate, and mentor engineers in India.

Requirements:

• 3+ years of professional software engineering, with substantial time owning production systems on AWS, including on-call.
• Strong AWS in production: ECS (Fargate), RDS/Aurora MySQL, ElastiCache (Redis or Valkey), ALB, VPC networking, and IAM.
• Infrastructure as code with Terraform: modules, multiple environments, safe changes.
• CI/CD with GitHub Actions and Docker, including environment promotion and rollback.
• Observability and operations: CloudWatch or similar, alert design, on-call, incident response, and root-cause analysis.
• Strong TypeScript and Node.js on the backend (Fastify, NestJS, or similar) and working React on the frontend.
• Cost awareness: has measured and reduced cloud costs.
• Security basics: secrets management, least-privilege access, web application security.
• Test-driven habits: defines a change by its tests and treats AI-written code as untrusted until verified.
• Clear written English. The team works across Japan and India, mostly asynchronously.
• A bachelor's degree or higher in computer science or a related field, or equivalent experience.

Nice to Have:

• Production experience with LLM-based products or AI agents (tool calling, streaming, and evals).
• Experience with Mastra, the Vercel AI SDK, or MCP.
• gRPC services and cross-account private networking (AWS PrivateLink).
• Web application firewalls and security monitoring.
• Tracking LLM token cost and routing work to cheaper models.
• Marketing tech, CRM messaging (LINE, SMS), or e-commerce.
• Mentoring engineers, or working in a cross-border team with Japan.
• Japanese language ability.

Tech Stack:

• Backend: TypeScript, Node.js, Fastify, Mastra on the Vercel AI SDK, Prisma, gRPC.
• Frontend: React 19, Vite, Tailwind.
• Data: Aurora MySQL, Valkey.
• Infrastructure: AWS (ECS Fargate, ALB, ElastiCache, Secrets Manager), Terraform, GitHub Actions, CloudWatch.

Skills

AWS, Node.js, React Native, React.js, Tailwind CSS, Terraform, TypeScript, Vite