import type { ImportExtension } from './utils';
/**
 * Detects appropriate import extension based on project configuration.
 *
 * Detection priority:
 * 1. Bundler config files present → 'none'
 * 2. Bundler in dependencies → 'none'
 * 3. moduleResolution: 'bundler' → 'none'
 * 4. moduleResolution: 'node16'/'nodenext' (or inferred from module) + allowImportingTsExtensions → '.ts'
 * 5. moduleResolution: 'node16'/'nodenext' (or inferred from module) → '.js'
 * 6. Otherwise → null (use default)
 *
 * Note: If moduleResolution is not set but module is 'Node16' or 'NodeNext',
 * moduleResolution is inferred per TypeScript's behavior.
 *
 * @param projectDir - Directory to analyze (where package.json/tsconfig.json are)
 * @returns Detected import extension or null if no detection could be made
 */
export declare function detectTypeScriptImportExtension(projectDir: string): Promise<ImportExtension | null>;