Full-Stack Dev — Claw-Machine Lead-Capture Kiosk (MVP)

We're building an MVP for a branded claw-machine trade-show activation: a touchscreen kiosk that captures an attendee lead, then unlocks one play on a commercial claw machine. This contract is a single-machine, end-to-end build. If it goes well there's more work ahead (fleet management, more interaction types, etc), but this post is scoped to the MVP only. WHAT YOU'LL BUILD (single machine, end to end) - Fluent with AI-assisted development and comfortable owning and reviewing AI-generated code. - A touchscreen kiosk app (Electron on Linux) running a "Data Collection" flow: the attendee fills out a short form/quiz on-screen. - Offline-first capture: the lead is written and durably persisted (fsync) BEFORE the machine unlocks, so we never lose a lead even if Wi-Fi or power drops. This is our #1 requirement. - Hardware unlock: after capture, the app fires a single credit pulse to the machine's existing coin-mechanism input via a USB opto-isolated relay board. The machine's native "play till you win" and prize detection stay intact. The app also reads the prize-detection line to log win vs. abandoned. - A basic cloud console (React + NestJS + PostgreSQL) to create/edit events and export captured leads as CSV. - The kiosk syncs event content from the cloud, then runs fully offline during the show. "HOW WE WORK (AI-FIRST)" section in the description (I'd place it right after TECH STACK): HOW WE WORK (AI-FIRST) This is an AI-assisted build and we expect you to work that way. We already have a detailed PRD + engineering spec (largely AI-generated) that you'll build from, not a blank page. You should be fluent with AI coding tools (Claude Code, Cursor, Copilot, Codex, etc.) to move fast — and equally disciplined about reviewing, testing, and hardening what the AI produces. You own correctness; the AI is a tool, not an excuse. Bonus if you've set up AI-driven workflows (agents, spec-to-code, auto-generated tests/CI) on real projects. TECH STACK (locked) TypeScript throughout. NestJS + Prisma + PostgreSQL (cloud). React + Vite (console). Electron on Linux/balenaOS (kiosk). SQLite (better-sqlite3) local store. serialport / node-hid for the hardware layer, with a mock controller so most of the app is built and tested with no physical machine. HARDWARE You will NOT need the physical machine to build ~90% of this (we provide a mock hardware controller). The real coin-pulse tuning is a short characterization step we'll coordinate. Comfort with serial/USB, GPIO, or embedded Linux (e.g., Raspberry Pi) is important. Safety rule: never fire pulses into an unattended machine; a person is always physically present during hardware testing. WHO WE'RE LOOKING FOR - Senior full-stack TypeScript engineer, LATAM-based (nearshore, US timezone overlap). - Strong on offline-first / data-integrity thinking (this matters more to us than fancy UI). - Some hardware-interfacing comfort (serial/USB/GPIO). You don't need to be an electronics engineer, but you shouldn't be scared of a relay and a multimeter. - Clear communicator who works in small, well-defined milestones. ENGAGEMENT Hourly, $45-60/hr depending on experience. ~1-3 months. One-off contract for this MVP. We have a detailed spec (PRD + engineering spec) to share with shortlisted candidates. PLEASE ANSWER THESE 3 QUESTIONS IN YOUR PROPOSAL: 1. Have you built an Electron (or similar) kiosk/desktop app that runs offline and syncs later? Share a link or a short description. 2. Have you interfaced software with hardware over serial/USB/GPIO (a relay, Arduino, Raspberry Pi, coin/vending mechanism, etc.)? Briefly, what did you build? 3. How do you guarantee a piece of captured data is never lost before a downstream action fires (write durability, retries, idempotency)? One or two sentences.