Principal Platform Engineer FULLY REMOTE ACROSS UK AND IRELAND Our client is a fast-scaling fintech building the next generation of payment infrastructure. They're merchant-first, engineering-led, and genuinely obsessive about outcomes over process. Small teams, real autonomy, hard problems. They're hiring a Principal Platform Engineer to own the design and delivery of a suite of Model Context Protocol (MCP) servers - the trusted, governed gateway between AI agents and their core payments platform. This is a hands-on principal role. You'll set technical direction and write production code, not just review it. What you'll be doing: Owning the architecture and delivery of MCP servers that expose platform data and capabilities to AI agents and internal developer tooling Designing the transport and session model (Streamable HTTP), including stateful sessions for progress streaming, subscriptions, sampling, and user elicitation flows Implementing robust OAuth-based authentication and author...