Need Experienced Senior Full Stack Engineer

Looking for a Senior Full-Stack Engineer to take a validated React prototype through production launch on AWS and deliver a clean handoff. This is not a greenfield architecture exercise. The product direction, reference architecture, data model, implementation plan, and major milestones are already defined. You will be responsible for turning that foundation into a secure, scalable, production-ready multi-tenant SaaS platform. You will own the stack end-to-end, from database design and tenant isolation through API, frontend, integrations, cloud infrastructure, auditability, and deployment. The target platform includes PostgreSQL 15 on RDS Multi-AZ with row-level security enforcing tenant isolation at the database layer; Node/TypeScript or Python APIs running on ECS Fargate; Cognito-based authentication and tenant context; Next.js 14 on Vercel with subdomain-based tenant routing; S3, SQS, SES, and Lob for document generation and delivery; Bedrock-based AI capabilities with complete input/output and decision logging; and integrations with Realware SOAP, Tyler REST, and Patriot SFTP. The database foundation is already drafted as 19 migrations across 29 tables, supported by architecture decision records. The broader foundation also includes a four-tenant reference architecture, a full project plan with WBS and milestone schedule, and five AI capabilities already specified for Bedrock. Key responsibilities include hardening and implementing the schema, defining production-grade RLS policies, building the API layer, refactoring the existing React prototype into the Next.js production application, implementing tenant routing and theming, creating a normalized integration layer across SOAP/REST/SFTP systems, establishing CI/CD, implementing comprehensive audit logging, and standing up the technical controls and evidence required for SOC 2 Type I. The engineer should be comfortable defending architecture and security choices in detail, including tenant isolation, Postgres RLS, audit immutability, encryption, document retention, migration strategy, background workers, and AWS design decisions. The right candidate has successfully shipped at least three multi-tenant B2B SaaS platforms or productionization engagements, has implemented PostgreSQL RLS in a real production environment, can work comfortably across database, backend, cloud infrastructure, and Next.js frontend code, and treats documentation, security, and auditability as first-class engineering deliverables. Experience in govtech, regtech, healthtech, fintech, or other compliance-heavy environments is a strong plus. Final deliverables include a fully operational production platform, completed integrations, deployment pipelines, SOC 2 Type I technical evidence, and a comprehensive handover package including architecture decision records, runbooks, migration documentation, integration playbooks, source code and deployment artifacts, and onboarding documentation. This is an execution-focused engagement: the plan and architecture are substantially defined. We are looking for someone who can pressure-test the design where necessary, make sound production decisions, and deliver the platform through launch and handoff.