Overview

Platform Foundations keeps many independent Platform apps consistent without a heavy in-house framework. It ships tokens and conventions, not a component library.

The source lives at PlainConceptsPlatform/Foundations.

How it works

PlainConcepts is a consultancy, so every app has its own team, domain, and lifecycle. The foundation shares the two things that benefit from being shared, and stays out of the way on everything else:

• The look, through one small token package every app installs.
• The conventions, through docs, a reference architecture, and installable agent skills.

A few decisions shape the whole thing, and it helps to know why:

• shadcn/ui with shared tokens, not a component library. Apps copy component source into their own repo, so they can read and edit it and are never locked into our versioning. What keeps them consistent is that they all import the same tokens. You get local control and a shared look at the same time.
• Tokens are the shared artifact, not components. One small package is cheap to maintain and hard to diverge from. To roll out a change everywhere, edit the tokens and bump the version.
• Pragmatic Feature-Sliced Design. Enough structure to scale, without forcing every layer on a small app. Start with three folders and earn the rest.
• The same stack we recommend. The foundation itself is Next.js, React, and TypeScript, so it dogfoods its own advice rather than shipping something it does not use.
• Backend is in scope too. The .NET conventions live here as well, sourced from the Plain engineering skills.

The result is meant to be a foundation teams actually adopt, not a platform that is impressive but expensive to live with.

What this showcase is for

• See the Platform theme applied to real components and screens.
• Copy the token names and patterns your app should use.
• It is not a copy of the shadcn docs. For full component APIs, use ui.shadcn.com.

Start here

What you get from the foundation

The stack

Next.js (App Router) + React + TypeScript, shadcn/ui on Radix + Tailwind v4, themed by @plainconceptsplatform/ui-theme, icons from Lucide. DI via inversify-hooks (mandatory). Package manager pnpm. The full stack list and repo layout are in the Architecture reference.