Plugin is missing a sanity.json file (Studio v2)

This page documents the Studio v2 parts system, which was removed in Studio v3. Current Sanity does not read sanity.json, and sanity start is now a deprecated alias that previews a production build — the dev server is sanity dev. For current plugin authoring, see Developing plugins.

You're probably here because you tried to run sanity start, but got:

No "sanity.json" file found in plugin "my-plugin-name"
See https://docs.sanity.io/help/missing-plugin-sanity-json

This can be fixed by adding a sanity.json file to the root level of the plugin in question. Also, you might want to define and/or implement a part, e.g.:

{
  "paths": {
    "source": "./src",
    "compiled": "./lib"
  },
  "parts": [
    {
      "name": "part:@sanity/base/components/unicorn-slider",
      "description": "React component which provides a slider input"
    },
    {
      "implements": "part:@sanity/base/components/unicorn-slider",
      "path": "components/Slider.js"
    }
  ]
}