Design.OrphanExport

Flags exports that no other file in the project imports — the most common form of dead code left behind by refactors.

Why

Single-file linters (like tsc's noUnusedLocals) miss this case: an export marked export is "used" from the file's perspective even if no consumer ever imports it. The waste is only visible when you look at the project as a whole.

What gets flagged

• export function foo() {} / export class Foo {} / export const x = ... whose name appears in zero import { ... } statements anywhere in the project.
• export default ... whose file is never the target of an import x from './that/file'.
• Local re-exports (export { x }) when neither x nor the file is reachable from any import or namespace touch.

What's not flagged

• Re-export forwarding nodes (export { x } from './y', export * from './y') — they're routing, not endpoints. Whether the underlying definition is consumed is what matters, and that's evaluated on its own row.
• Anything in test or mock files, by default. Configurable via test_file_patterns.
• Type-only exports (export type X, export interface I, export type { X } from './m'), unless include_type_only = true. Type-only consumption is harder to attribute reliably without full type-aware analysis; opt in if your project's types matter as much as its values.
• Files reached via import * as ns from './m' — namespace imports are treated as touching every named export of the target file. If you want finer-grained tracking, switch the consumer to named imports.

Configuration

[checks."Design.OrphanExport"]
include_type_only = false  # set true to flag unused type-only exports
test_file_patterns = [".test.", ".spec.", "_test.", "_spec.", "/__tests__/", "/__mocks__/"]

Limitations

• Only static import and export declarations are tracked. require(), module.exports = ..., and dynamic import('...') calls are ignored — flagged exports that are reached only through dynamic loading will be false positives.
• No package.json main/module/exports allowlist yet — public-API entry points appear orphan if no in-project file imports them. Run with the project's published surface in mind for now; an allowlist is a planned follow-up.
• Re-export chain attribution stops at the immediate re-exporter; if your intermediate barrel re-exports x and only the barrel is consumed, the underlying x will (correctly) be considered touched. If the barrel itself is also unused, you'll see two findings rather than one — pick a side and fix that file.