Senior Full-Stack Engineer (TypeScript)

Description

Summary: This role involves building human-to-agent interaction surfaces, including dashboards, approval flows, real-time visualizations, and counterparty portals. Highlights: 1. Architecting real-time, event-driven TypeScript/React applications. 2. Designing data visualization and API layers for multi-tenant SaaS. 3. Developing secure authentication and session management systems. You'll build the surfaces through which humans interact with our agents — dashboards, approval flows, real\-time visualizations, and the counterparty portal that pulls new companies into the network. **What you'll do** * **Chat \& real\-time architecture** — WebSocket\-based event streaming, agent notification routing, dynamic query handling. * **Cash forecast visualization** — Probabilistic forecasts with uncertainty bands and drill\-down into underlying invoices and assumptions. * **Counterparty portal** — A lightweight portal where suppliers and customers can see invoice status, disputes, and payment promises via secure magic links. * **Approval UI** — The human\-in\-the\-loop interface where agent reasoning and source documents are reviewed before actions are approved. * **Authentication \& session management** — OAuth 2\.0 / OIDC integration, JWT with tenant context, session lifecycle (Redis\-backed), magic link token issuance for the counterparty portal. * **API / BFF (Backend\-for\-Frontend) layer** — The TypeScript service layer that mediates between the React frontend and the Python agent backend. REST, GraphQL, and WebSocket endpoints with tenant\-scoped security. * **MCP server** — A Model Context Protocol endpoint for external AI agent integration, enabling agent\-to\-agent interoperability across the supply chain. **What we're looking for** * 5\+ years architecting TypeScript/React applications in production. * Systems design instincts — you think in components, contracts, data flows, and failure modes. * Deep experience with real\-time architectures (WebSockets, event\-driven frontends). * Experience designing data visualization systems and API layers for multi\-tenant SaaS. * Strong understanding of frontend security (CSP, CSRF, session management, input sanitization). * Effective use of AI coding tools with strong code review skills for security\-sensitive output. * Strong product sense. You have opinions, you back them with data and gut, and you speak up.