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@studnicky/single-export ​

Each non-index source file must export exactly one named symbol, and the export name must match the filename base (case-insensitively, supporting camelCase, PascalCase, and SCREAMING_SNAKE_CASE for constant modules). Default exports are forbidden in all files. export * is forbidden outside index files.

Index files (index.ts, index.mts, index.cts, index.tsx) are exempt from the single-symbol limit but still forbid default exports.

Restricted topology may be expressed either as folders (entities/, errors/, interfaces/, constants/, types/) or as filename suffixes such as user.constants.ts and request.types.ts. Those modules are exempt from the single-symbol and filename-match checks. Outside that topology, enum files are exempt only when every export is an enum or a const value.

Constant modules have an additional constraint: every exported symbol must use SCREAMING_SNAKE_CASE.

Fixable: No · Options: No · Suggested severity: error

✗ Incorrect ​

ts
// userService.ts — multiple named exports
export class UserService { /* ... */ }
export class AdminService { /* ... */ }
ts
// userService.ts — default export
export default class UserService { /* ... */ }
ts
// userService.ts — export name does not match filename
export class UserManager { /* ... */ }

✓ Correct ​

ts
// UserService.ts — single named export matching filename
export class UserService { /* ... */ }
ts
// index.ts — multiple exports are allowed in index files
export { UserService } from './UserService.js';
export { AdminService } from './AdminService.js';
ts
// entities/UserEntity.ts — entity files may export their schema trio
export const UserEntitySchema = { type: 'object' } as const;
export type UserEntity = { id: string };
export function validateUserEntity(candidate: unknown): candidate is UserEntity { return true; }
ts
// http.constants.ts — constant modules may use fractal filename topology
export const DEFAULT_TIMEOUT = 1_000;
export const MAX_RETRIES = 3;
ts
// Direction.ts — enum files may also export companion constants
export enum Direction { Up, Down }
export const DEFAULT_DIRECTION = Direction.Up;