Build a working web app on the user's own accounts and put it live on their Cloudflare domain. Do every step yourself with the CLIs and only ask for what needs a human (a browser login, a device code, a payment, a secret key). Talk to the user in their language, short messages, no jargon. For a private tool only the user and their agent use, switch to create-internal-app; for a page with no sign-in, switch to create-landing.

If you got this skill from a link instead of a local folder, install nothing else from the repo: download a file it links only when a step needs it, with curl -fsSL https://raw.githubusercontent.com/Melvynx/ai-maxxing-skills/main/skills/create-software/<path> -o <scratch>/<file> (for example references/fast-app.md), and read another skill it names only when you reach it, from https://raw.githubusercontent.com/Melvynx/ai-maxxing-skills/main/skills/<skill-name>/SKILL.md.

Keep this stack unless the user asks to swap a layer:

App, routing, server functions: TanStack Start (React, TypeScript, Vite).
UI: shadcn/ui on Base UI + Tailwind CSS v4, lucide-react icons, sonner toasts.
Database, backend, files, crons: Convex for everything, no other database or API server.
Auth: Better Auth through @convex-dev/better-auth, email OTP by default.
Marketing and login emails: Lumail through @lumail/convex.
Payments, only if the app sells: Stripe Checkout with the stripe-checkout skill.
Video: Tella embeds from the URL the user pastes.
Hosting, domain, DNS: Cloudflare Workers with @cloudflare/vite-plugin, deployed with cf.
Code: Git and one private GitHub repo.

Reach for the TanStack library before any other package for client jobs: @tanstack/react-query + @convex-dev/react-query (convexQuery(api.x.y, args)) for fetching and cache, @tanstack/react-table for lists, sorting, filters and pagination, @tanstack/react-virtual for long lists, @tanstack/react-form + zod for forms, @tanstack/markdown to render markdown, @tanstack/react-hotkeys for shortcuts (cmd+k, j/k, esc), @tanstack/react-pacer to debounce search and throttle saves, @tanstack/ai-react for AI chat or generation. Check each package's current API (npm view <pkg> version, then its README or find-docs) instead of writing it from memory.

Check access and fix what fails with the matching setup skill (setup-github, setup-cloudflare, setup-convex, setup-lumail, setup-node when npx is missing) before writing code. When a login needs the browser, give the exact link or code and wait for "done".