feat: enhance alias handling and package entry point detection in debarrel codemod

.changeset/beige-sheep-draw.md

@@ -0,0 +1,5 @@
+---
+"debarrel": patch
+---
+
+Fix debarreling codemod's issue with alias imports

codemods/debarrel/scripts/codemod.ts

@@ -7,6 +7,7 @@ import {
   hasPackageJson,
   isBarrelFile,
   isInsideNodeModules,
+  isPackageEntrypoint,
 } from "./utils/paths.ts";
 import { isPureBarrel } from "./utils/barrel.ts";
 import { resolveSpecifier, type SpecRewrite } from "./utils/specifiers.ts";
@@ -136,12 +137,12 @@ const codemod: Codemod<Language> = async (root, options) => {
   rewriteMockCalls(rootNode, barrelRewrites, edits);
 
   // Barrel rename — skip files inside node_modules or inside a package
-  // (renaming a package entry point would break consumers importing via
-  // the package name).
+  // when the barrel is an actual package entrypoint (renaming it would break
+  // consumers importing via the package name).
   if (
     isBarrelFile(filename) &&
     !isInsideNodeModules(filename) &&
-    !hasPackageJson(filename)
+    (!hasPackageJson(filename) || !isPackageEntrypoint(filename))
   ) {
     const { pure, hasWildcards } = isPureBarrel(rootNode);
     if (pure && !hasWildcards) {

codemods/debarrel/scripts/utils/paths.ts

@@ -69,12 +69,94 @@ function fileExists(filePath: string): boolean {
   }
 }
 
-export function hasPackageJson(filename: string): boolean {
+function readJsonFile(filePath: string): unknown | null {
+  try {
+    return JSON.parse(fs.readFileSync(filePath, "utf8"));
+  } catch {
+    return null;
+  }
+}
+
+function normalizePackageTarget(target: string): string {
+  return target.replace(/\\/g, "/").replace(/^\.\//, "");
+}
+
+function collectExportTargets(value: unknown, targets: string[]): void {
+  if (typeof value === "string") {
+    targets.push(normalizePackageTarget(value));
+    return;
+  }
+
+  if (!value || typeof value !== "object") return;
+
+  if (Array.isArray(value)) {
+    for (const item of value) collectExportTargets(item, targets);
+    return;
+  }
+
+  for (const nested of Object.values(value)) {
+    collectExportTargets(nested, targets);
+  }
+}
+
+export function findNearestPackageJson(filename: string): string | null {
   let dir = path.dirname(filename);
   const root = path.parse(dir).root || "/";
-  while (dir !== root) {
-    if (fileExists(path.join(dir, "package.json"))) return true;
+  while (true) {
+    const packageJsonPath = path.join(dir, "package.json");
+    if (fileExists(packageJsonPath)) return packageJsonPath;
+    if (dir === root) return null;
     dir = path.dirname(dir);
   }
-  return false;
+}
+
+export function getPackageName(filename: string): string | null {
+  const packageJsonPath = findNearestPackageJson(filename);
+  if (!packageJsonPath) return null;
+  const parsed = readJsonFile(packageJsonPath);
+  if (!parsed || typeof parsed !== "object") return null;
+  const name = (parsed as { name?: unknown }).name;
+  return typeof name === "string" && name.length > 0 ? name : null;
+}
+
+export function hasPackageJson(filename: string): boolean {
+  return findNearestPackageJson(filename) !== null;
+}
+
+export function isPackageEntrypoint(filename: string): boolean {
+  const packageJsonPath = findNearestPackageJson(filename);
+  if (!packageJsonPath) return false;
+
+  const parsed = readJsonFile(packageJsonPath);
+  if (!parsed || typeof parsed !== "object") return false;
+
+  const packageDir = path.dirname(packageJsonPath);
+  const relativeFilename = path
+    .relative(packageDir, filename)
+    .replace(/\\/g, "/");
+  if (!relativeFilename || relativeFilename.startsWith("../")) return false;
+
+  const manifest = parsed as {
+    main?: unknown;
+    module?: unknown;
+    types?: unknown;
+    typings?: unknown;
+    exports?: unknown;
+  };
+  const entrypoints: string[] = [];
+
+  for (const field of [
+    manifest.main,
+    manifest.module,
+    manifest.types,
+    manifest.typings,
+  ]) {
+    if (typeof field === "string") {
+      entrypoints.push(normalizePackageTarget(field));
+    }
+  }
+
+  collectExportTargets(manifest.exports, entrypoints);
+
+  return entrypoints.includes(relativeFilename);
 }

codemods/debarrel/scripts/utils/specifiers.ts

@@ -2,14 +2,24 @@ import type { SgNode, SgRoot } from "codemod:ast-grep";
 import type { Language } from "./language.ts";
 import { getStringContent } from "./ast.ts";
 import {
-  hasPackageJson,
+  getPackageName,
   isBarrelFile,
   isInsideNodeModules,
   isLocalRelativePath,
   joinImportPaths,
 } from "./paths.ts";
 import { parseBarrelExport } from "./barrel.ts";
 
+function getImportPackageName(importPath: string): string | null {
+  if (importPath.startsWith("@")) {
+    const segments = importPath.split("/");
+    return segments.length >= 2 ? `${segments[0]}/${segments[1]}` : null;
+  }
+
+  const [packageName] = importPath.split("/");
+  return packageName || null;
+}
+
 export interface SpecRewrite {
   consumerName: string;
   newImportPath: string;
@@ -34,12 +44,16 @@ export function resolveSpecifier(
   // package.json "exports" that would break if we change the import subpath.
   if (isInsideNodeModules(def.root.filename())) return null;
 
-  // For non-relative imports (package names, aliases), skip if the resolved
-  // file lives inside a package (has a package.json ancestor). The package's
-  // "exports" field controls valid subpaths — rewriting the import could
-  // produce a path that isn't exported (e.g. @acme/validators → @acme/validators/foo).
-  if (!isLocalRelativePath(importPath) && hasPackageJson(def.root.filename())) {
-    return null;
+  // For non-relative imports, only preserve the package boundary when the
+  // resolved file belongs to the same named package as the import specifier.
+  // This keeps tsconfig aliases like `~/foo` or `@acme/pkg/*` rewriteable
+  // even when the surrounding repo has an unrelated package.json.
+  if (!isLocalRelativePath(importPath)) {
+    const packageName = getPackageName(def.root.filename());
+    const importPackage = getImportPackageName(importPath);
+    if (packageName && importPackage === packageName) {
+      return null;
+    }
   }
 
   if (isBarrelFile(def.root.filename())) {

codemods/debarrel/tests/tsconfig-alias-paths/expected/package.json

@@ -0,0 +1,3 @@
+{
+  "name": "fixture-app"
+}

codemods/debarrel/tests/tsconfig-alias-paths/input/package.json

@@ -0,0 +1,3 @@
+{
+  "name": "fixture-app"
+}