folder-index-file

an `index.ts` in a folder that is not a package's entry

Deterministic checkadvisory by defaultbasecode

The argument

No Folder Index Files

An index.ts is a package's entry — the file its manifest publishes to other packages — and nothing else.

Every import already names the declaring file, so an index.ts in a folder lists names that nothing reads through it. It is a second copy of what the folder holds, kept by hand, that drifts the first time someone adds a file and forgets it.
A package's entry stays. Other packages import it, so it is the package's contract. It sits at the package root or its src/, or the manifest names it — a subpath export such as "./contracts": "./src/contracts/index.ts" makes that file an entry too.
A route is not an index file. A file router's src/routes/index.tsx is a route the framework loads.

Delete a folder's index.ts, and import each name from the file that declares it.

The proof

fail

export { ingestRecords } from './ingestRecords';

pass

{
	"name": "folder-index-file-pass-fixture",
	"private": true,
	"exports": { ".": "./src/index.ts" },
	"dependencies": {
		"@tanstack/react-router": "1.168.3",
		"@tanstack/react-start": "1.167.5"
	}
}

Turn it down

Both lines go in your lightsout.config.json.

"standards-checks": { "folder-index-file": "advisory" }

"standards-checks": { "folder-index-file": "off" }