Full-Stack AI-Friendly Developer

FULL-STACK DEVELOPER Location: Remote Type: Full-Time Compensation: Competitive, commensurate with experience ABOUT US Market Muscles is a SaaS platform serving martial arts and dance studios across the country. Our CRM handles everything from contact management and billing (Stripe + Authorize.Net) to scheduling, communications (Twilio VoIP/SMS), student portals, AI-assisted coaching, and website building — all under one roof. We move fast, ship often, and rely heavily on AI-assisted development to keep pace with our growing client base. THE ROLE We're looking for a senior full-stack developer who can hit the ground running on a mature, production React + Supabase codebase. You'll be squashing bugs, shipping features, and improving code quality across the platform — working alongside our existing team and leveraging AI tools to maximize your throughput. This is not a "prompt an AI and hope for the best" role. We expect you to use AI as a force multiplier — generating drafts, exploring solutions, and accelerating boilerplate — while exercising the engineering judgment to verify, refactor, and own every line that ships to production. WHAT YOU'LL WORK WITH FRONTEND * React 18 + TypeScript (client-side SPA, not Next.js) * Vite 5 build tooling * Tailwind CSS v3 + shadcn/ui (Radix primitives) * Semantic design tokens with no raw color classes * React Router v6 * React Hook Form + Zod validation * TanStack React Query for server state * TipTap rich text editor * Recharts for data visualization * Capacitor for native iOS/Android wrappers BACKEND / DATABASE * Supabase — Postgres, Auth, Storage, and Edge Functions * PostgreSQL with Row-Level Security (RLS) * Multi-tenant architecture: Business → Location → User * Deno Edge Functions (100+ in production) * pg_cron for scheduled background jobs PAYMENTS & INTEGRATIONS * Stripe — subscriptions, invoices, POS, and Connect * Stripe API version 2025-08-27 * Authorize.Net * Dual-gateway architecture — every payment path must support both Stripe and Authorize.Net * Twilio — SMS, VoIP via @twilio/voice-sdk, and SIP desk phones * Resend — transactional and inbound email * ElevenLabs — AI voice assistant * Google Calendar API * Facebook Graph API * Zapier webhooks AI / LLM * Gemini (Google) for chat, document generation, and schema extraction * pgvector for RAG embeddings * Internal AI assistant ("Kai") with tool-calling and voice mode DEV TOOLING * Vitest + React Testing Library for unit tests * Playwright for E2E testing * ESLint * Supabase CLI * Docker for the local Supabase stack WHAT WE'RE LOOKING FOR MUST-HAVE SKILLS * 3+ years building production React + TypeScript applications * Strong PostgreSQL experience * Ability to write and debug RLS policies * Understanding of multi-tenant data isolation * Ability to read and understand query plans * Comfortable writing Deno/TypeScript Edge Functions * Experience with Stripe or similar payment integrations * Solid understanding of CSS/Tailwind * Ability to build responsive, accessible UIs without fighting the design system * Experience working with REST APIs and webhooks such as Twilio, Stripe, Resend, and similar services AI-ASSISTED DEVELOPMENT — THE DIFFERENTIATOR * You're fluent with AI coding tools such as Claude Code, GitHub Copilot, Cursor, ChatGPT, or equivalent tools * You use AI to accelerate your work, including drafting implementations, exploring unfamiliar code, generating test cases, explaining complex logic, and triaging bugs * You understand AI's limitations and review, verify, and refactor everything it produces * You can diagnose problems from logs and data by reading Edge Function logs, querying the database, and tracing issues across the stack before asking AI for a fix * You know how to prompt effectively by providing context, constraints, and examples to get production-grade output rather than generic boilerplate * You treat AI output like a pull request from a junior developer — it's a good starting point, but you're the senior reviewer responsible for making sure it meets the bar CODE QUALITY STANDARDS * You write code that other humans and AI tools can understand * You use clear naming, small functions, and logical separation * You don't ship AI-generated code blindly — you read it, test it, and own it * You understand the difference between "it works" and "it's correct" * You think about edge cases, race conditions, failures, and what happens when the network goes down * You're comfortable with code review, including both giving and receiving constructive feedback * You write meaningful tests designed to catch regressions rather than simply increase coverage percentages NICE-TO-HAVE * Experience with Supabase, including RLS, Edge Functions, and PostgREST quirks * Capacitor or mobile development experience for iOS and Android * Background in SaaS billing or subscription management * Familiarity with the martial arts or fitness studio industry * Experience with AI/LLM integrations, including prompt engineering, function calling, embeddings, and RAG * Open-source contributions or an active developer community presence WHAT YOU'LL BE DOING DAY-TO-DAY Bug Triage & Fixes: Clients report issues. You'll investigate logs, query the database, reproduce the problem, and ship a fix. AI may assist with drafting solutions, but you're responsible for verifying the final result. Feature Development: Take a feature from concept and specification through production, working across both the frontend and backend. Code Quality Improvements: Refactor existing code, add tests, improve type safety, and clean up technical debt. Integration Maintenance: Keep Stripe, Twilio, Authorize.Net, and other third-party integrations healthy as their APIs evolve. Code Review: Review both AI-generated and human-authored pull requests while holding both to the same quality standards. Documentation: Keep internal documentation and CLAUDE.md, our AI context file, accurate as the codebase evolves. HOW WE WORK WITH AI We don't just tolerate AI tools — we've built our workflow around them. Our team uses AI to: * Generate initial implementations and boilerplate * Explore unfamiliar parts of the codebase * Draft tests and documentation * Debug issues by analyzing error logs and stack traces * Suggest refactors and optimizations But the human developer is always the reviewer, the owner, and the person who signs off on the work. If you've used AI to dramatically increase your development output while maintaining — or improving — code quality, we want to talk. HOW TO APPLY Send us: 1. Your resume 2. A short note — just a few paragraphs — explaining how you use AI tools in your development workflow, including what works, what doesn't, and how you maintain quality. 3. One or two examples of your work. This could include a pull request, a project, an open-source contribution, or a write-up of a difficult bug you solved. BONUS: Tell us about a time AI gave you the wrong answer and how you caught it.