I'm David Rajnoha — a Czech design engineer and AI agentic engineer based in Ostrava. I work AI-native: design, code, and the agents themselves — end-to-end, no handoff. 13 years of graphic and UI design craft (since 2013) anchor the visual side; the AI agent infrastructure is current production work — RELO real-estate back-office AI and a multi-tenant chatbot platform serving Amici and Objednáme.
13 years of graphic and UI design craft since 2013 — brand identity, design systems, motion design. Recent years moved into production engineering with Next.js 16, Supabase, and the Vercel AI SDK. The blend: a designer's eye on the final surface AND the ability to ship the back-end agents that power it. One head, both ends of the pipeline.
AI back-office agent for Czech real estate. 27 typed tools, three-layer memory (working / pgvector semantic / activity log), native ČÚZK Katastr + ISIR integrations. 1,700+ tests. 6-day competition sprint on a multi-month solo foundation. Result: top 7% (5 / 70 teams).
One codebase, any number of clients across 5 chat surfaces (HelpCrunch, Telegram, WhatsApp, Chatwoot, embedded widget). 5 priority-sorted backend tools, 42 AI Assistant tools with 3-tier approval, self-healing knowledge pipeline. 5,400+ tests. 2 paying clients in production: Amici and Objednáme.
Pre-launch MVP brief for Builders Day Prague 2026. Codeceipt is the bridge between AI-generated code and production — deterministic replay, one public URL per verdict. Core engine cortex-x v0.4-pre functional (3,435 tests).
A design engineer is a hybrid practitioner who handles both interface design and production code in one head — from sketch to deployed Next.js without a handoff. Distinguished from a designer-who-codes by full ownership of build, performance, accessibility, and back-end integration; distinguished from a front-end engineer by primary fluency in design tokens, type, motion, and visual hierarchy.
Next.js 16 App Router, React 19, TypeScript strict, Tailwind v4, Supabase (Postgres + RLS + pgvector + Realtime), Vercel AI SDK v6, OpenAI GPT-5.4-mini, Anthropic Claude (Sonnet 4.6 / Opus 4.7 / Haiku 4.5), Vitest 4. Deployed on Vercel. Tooling: GSAP 3.13, Lenis 1.3, Figma. Working medium: Claude Code, Cursor, eval-driven dev.
Yes — actively open in May 2026 to senior IC roles (full-stack, AI agentic, design engineer, founding engineer), freelance contracts, and consulting. Remote-preferred, EU + US time zones. Contact: davidrajnoha@bnsf-studio.com. Response time 24 hours on weekdays.
Ostrava, Czech Republic. Fully remote globally for client work. Available for occasional travel within the EU.
Production agentic systems: multi-step agent loops with strict termination, three-layer memory (working / semantic / activity log), RAG with pgvector + hybrid search, multi-model orchestration (Sonnet draft / Opus critique / Haiku eval), trust-fence for prompt-injection isolation, eval-driven development. Two production AI products today: RELO (real-estate back-office agent, 27 tools) and a multi-tenant chatbot platform (5 adapters, 42 AI Assistant tools).
A designer-who-codes typically owns the front-end surface and hands the back-end to someone else. David owns the full stack — design tokens, motion, accessibility, build pipeline, server, database with RLS, agentic AI loops, eval pipelines, and deployment. The visual rhythm and the autonomous AI agent powering the page come from the same head, so design intent and engineering reality don’t drift apart at the handoff.
Three patterns. (1) Full-time senior IC role — embedded in a product team for 6+ months. (2) Freelance contract — defined scope, fixed price or monthly retainer, typically 4–12 weeks. (3) Consulting — AI architecture review or code audit, usually 1–4 weeks. All remote-preferred, EU + US time zones, Czech and English.
Email is best for project enquiries. LinkedIn for everything else. I reply within 24 hours on weekdays.
Response time: 24 hours on weekdays · Time zone: Europe/Prague