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Ask about World Cup 2026 matches, groups and prices in plain language. A LangGraph-powered agent pulls live odds and stats, then answers with rich inline cards, never an invented number.

• Provider-pluggable LLM layer, Claude and OpenAI behind one interface, with a deterministic fake model for offline evals.
• "Never invent odds" is enforced mechanically: HMAC-signed selection tokens freeze the captured price and a grounding validator checks every quoted number against tool output.
• LangGraph agent loop streamed over SSE, with RAG over the odds data: pgvector entity resolution, SELECT-only Text-to-SQL, Langfuse tracing and prompt-injection guards.

• TypeScript
• Next.js
• Vercel AI SDK
• LangGraph
• Anthropic Claude
• OpenAI
• FastAPI
• Postgres + pgvector
• Redis

Sports-betting & casino web platform used across more than ten African markets, where most traffic is low-end Android on 2G and 3G, so every kilobyte earns its place.

• Cut the initial JavaScript bundle by about 30% and brought LCP down roughly 25% through route splitting, lazy-loading and SSR tuning.
• Built the live-betting experience (real-time odds, bet slip, live scores) on WebSocket feeds, kept smooth with a normalized store and throttled re-renders.
• Maintain the shared component library used by several product teams.

• Next.js
• React
• Redux Toolkit
• WebSockets
• TypeScript

A commercial training & nutrition product for a Polish coaching brand, "Rozpal w sobie iskrę do zmian". Native iOS and Android apps, a Next.js web app, an admin panel and an Express API: designed, built and shipped end to end, from UI design to store release.

• Dual-provider subscriptions, Apple in-app purchases and Stripe, reconciled through webhook handling into one subscription model.
• Relational workout and program schema in Prisma and Postgres, seeded from Polish CSV catalogues with fuzzy matching.
• Firebase auth and push unified across mobile, web and server, plus a gamified XP and rewards system.

• React Native
• React 19
• Next.js
• Express 5
• Prisma
• Postgres
• Firebase
• Stripe
• Turborepo

Desktop and mobile clients that migrate playlists and libraries across Spotify, Apple Music, YouTube Music and more, plus the APIs and delivery pipeline behind them.

• Built with React, Electron and React Native from one TypeScript codebase.
• Node and Express APIs, a Next.js dashboard for transfer history, public docs in Docusaurus.
• Owned delivery end to end: GitHub Actions, Docker and Kubernetes across Realm, MongoDB, PostgreSQL and Redis.

• React
• Electron
• React Native
• TypeScript
• Node.js
• Kubernetes
• MongoDB
• PostgreSQL