core-quality-unused-export

Pack: core-quality Default severity: MAJOR Languages: TypeScript, JavaScript Lifecycle: experimental Confidence: 0.7

What it catches

export declarations whose exported name is not referenced by any import { Name } anywhere else in the project. Cross-file pivot debris: the consumer was rewired or removed but the export was forgotten.

The check is name-based, using the allImportedNames set built once per scan from every TS/JS file. The rule does NOT do path resolution — if Foo is imported anywhere by name, every Foo export in the project is considered used. This is the SAFE direction (under-reports rather than over-reports).

Why this matters for vibe-coded apps

The single most common cross-file vibe-coding artifact: a feature gets rewritten or removed, the consumer is deleted, the export stays behind. The exported NAME often reveals what the dead concept was — oldAuthCheck, legacyValidate, previousAdminFlag — and the AI may try to re-import it when working on a future fix, locking in obsolete behaviour.

Example — flagged

// src/legacy.ts
export function oldAuthCheck(token: string): boolean { ... }   // ← flag
export const legacyMaxRetries = 7;                              // ← flag
export interface UnusedShape { id: string; legacyFlag: boolean; }  // ← flag
export type UnusedAlias = number | string;                      // ← flag
export function used(): string { return 'ok'; }                 // imported by entry.ts → silent

// src/entry.ts
import { used } from './legacy';

Example — not flagged

• The export is consumed by another file in the project (any name match anywhere).
• The file is an entry-point basename: index.ts, route.ts, page.tsx, layout.tsx, middleware.ts, main.ts, server.ts, cli.ts, framework config (next.config.js, tailwind.config.ts, etc.). Their exports flow to a runtime that the rule can't see.
• The export name is `_`-prefixed (TS convention for deliberately unused).
• The export is a `export default` (default imports often bind to arbitrary local names; too noisy to flag in v1).
• The file is a test file (*.test.ts / *.spec.ts) — exports there feed the test runner.

Suggested fix

• Genuine pivot debris: drop the export. If nothing else in the file references it either, delete the whole declaration. (core-quality-unused-variable will catch any leftover binding.)
• Should be consumed: find the call site that needs the export and add the import.
• Public package surface (the consumers live outside this repo): suppress with a Reason comment. The rule doesn't yet parse package.json#exports to recognise these automatically.

Suppressing

// Reason: re-exported via barrel `src/index.ts` for external consumers; the analyser
// only sees imports inside this repo.
// codemore-ignore-next-line: core-quality-unused-export
export function publicHelper(): void {}

The directive must be on the line immediately before the target. If you put a comment between them, the directive suppresses the comment instead.

Implementation

Uses ProjectIndex.allImportedNames, a set populated once per scan from every TS/JS file's import clauses (default name, namespace name, both local alias and original name from named-import specifiers). The rule walks the current file's top-level export declarations (function / class / interface / type / enum / variable-statement / export { X }) and emits a finding for every name that isn't in the imported-names set.

Coverage gap:

• Name collision: if Foo is exported by two files but only one is consumed, both stay marked "used". Safe direction.
• Dynamic imports (import('./x').then(m => m.Foo)) — not tracked.
• `package.json#exports` — not consulted; library packages should suppress with a Reason comment until v1.1 lands the parse path.

Source: `shared/packs/core-quality/core-quality-unused-export.ts` Fixtures: `corpus/rules/core-quality-unused-export/`