Function resolveAliasedImport

src/resolution/import-resolver.ts:440–497

* Resolve an aliased/absolute import. * * Tries, in order: * 1. Project-defined `compilerOptions.paths` (tsconfig/jsconfig). * Each pattern can have multiple replacements; tried in tsconfig * priority order with extension permutations. * 2. The legacy hard-coded fallback list (`@

(
  importPath: string,
  projectRoot: string,
  language: Language,
  context: ResolutionContext
)

 *   3. Direct path lookup (with extensions).
 */
function resolveAliasedImport(
  importPath: string,
  projectRoot: string,
  language: Language,
  context: ResolutionContext
): string | null {
  const extensions = EXTENSION_RESOLUTION[language] || [];
  const tryWithExt = (basePath: string): string | null => {
    for (const ext of extensions) {
      const candidate = basePath + ext;
      if (context.fileExists(candidate)) return candidate;
    }
    if (context.fileExists(basePath)) return basePath;
    return null;
  };

  // 1. Project tsconfig/jsconfig paths.
  const aliasMap = context.getProjectAliases?.();
  if (aliasMap) {
    const candidates = applyAliases(importPath, aliasMap, projectRoot);
    for (const c of candidates) {
      const hit = tryWithExt(c);
      if (hit) return hit;
    }
  }

  // 1.5 Workspace packages (`@scope/ui/widgets` → `packages/ui/widgets`).
  //     Resolves a monorepo member import to the member's directory; the
  //     extension/index permutations below then find its barrel (#629).
  const workspaces = context.getWorkspacePackages?.();
  if (workspaces) {
    const base = resolveWorkspaceImport(importPath, workspaces);
    if (base) {
      const hit = tryWithExt(base);
      if (hit) return hit;
    }
  }

  // 2. Hard-coded fallback list. Kept for projects that use these
  //    conventional aliases without declaring them in tsconfig.
  const fallbackAliases: Record<string, string> = {
    '@/': 'src/',
    '~/': 'src/',
    '@src/': 'src/',
    'src/': 'src/',
    '@app/': 'app/',
    'app/': 'app/',
  };
  for (const [alias, replacement] of Object.entries(fallbackAliases)) {
    if (importPath.startsWith(alias)) {
      const hit = tryWithExt(importPath.replace(alias, replacement));
      if (hit) return hit;
    }
  }

  // 3. Direct path.
  return tryWithExt(importPath);
}