Forward-Deployed Engineer / Tech Lead — .NET + React + AI (proposal now, build if we win)

We're a boutique AI and data consultancy that acts as a fractional AI/engineering team for our clients. We're pursuing a significant engagement and I'm looking for a sharp engineer to partner with - first on the bid, then on the build. The immediate ask (this week, possibly the next ~2 weeks): I need a partner to help me write a winning technical proposal for a competitive RFP. That means co-architecting the solution, shaping the phased delivery plan, writing the technical approach, and pressure-testing estimates. Strong technical writing and clear thinking matter as much as coding here. If we win (the bigger picture): You stay on as the forward-deployed engineer - the technical lead who talks directly to the client and owns the engineering side of delivery, working alongside me. Part-time now, scaling toward full-time on award. This is a relationship I want to grow, one step at a time. Note on scope: If we win, you'll run the technical side to start. As the build scales, we'll bring on a dedicated data engineer and a dedicated infrastructure/DevOps person. Your focus stays on application engineering, AI integration, and client-facing technical leadership - not data pipelines or infra ownership. Knowing where your scope ends is part of the role. The work (generic - details under NDA): A hotel procurement company needs their existing .NET + React (SQL Server) enterprise application revived and modernized to a current stack - revived, not rebuilt - and a sovereign, on-premise data foundation stood up beneath it, with an AI layer (a separate Python service: RAG, agents, governed tool/MCP access) layered on top once the data is trustworthy. Data-residency and on-prem constraints are central. You are: - Senior/lead with real depth in .NET + React + SQL Server - Experienced modernizing / refactoring existing enterprise apps (not just greenfield) - security hardening, test coverage, CI/CD, version upgrades - AI-integration literate - comfortable wiring an app to an AI service (LLM/RAG/agent endpoints, tool interfaces); you don't have to be the ML researcher, but you get how it fits together - Genuinely client-facing - excellent spoken and written English, calm and credible in front of stakeholders, can run a technical conversation solo - Able to write a crisp technical proposal, not just code - Available this week with meaningful GMT+4 working-hours overlap Nice to have: Python/FastAPI, PostgreSQL/pgvector, on-prem/sovereign or regulated-industry delivery, procurement/ERP domain, .NET 8/10 migration experience. Engagement: Hourly, part-time to start (~10-20 hrs/wk), scaling toward full-time if the build is awarded. $60-160/hr depending on seniority and fit. Long-term potential for the right person. To apply (please - no generic/AI-spray applications; I read every word): Start your reply with the word "Sovereign" so I know you read this.