fix(build): use basename to detect package.json in copyTracedFiles

[ash1day]

What

copyTracedFiles decides whether a traced file is a node-package manifest with

if (module.endsWith("package.json")) {
  nodePackages.set(path.dirname(module), path.dirname(dst));
}

endsWith matches any filename whose tail is package.json, so files like care-package.json or my-package.json get registered as if their parent directory were a node package. The map is then handed to the Cloudflare adapter's copyWorkerdPackages, which tries to read <parent-dir>/package.json and surfaces:

ERROR Failed to copy /path/to/data/tables

The actual file copy is unaffected — that goes through filesToCopy, which is keyed by full paths — so the error is purely cosmetic. But it's misleading enough that someone hitting it usually has to dig into OpenNext's source to convince themselves the deploy is fine, which is what motivated this patch.

Repro

In a Next.js app, statically import a JSON data file whose name ends in -package.json:

// src/lib/foo.ts
import careData from '@@/data/tables/care-package.json' assert { type: 'json' };

Next traces that file, OpenNext walks the .nft.json, and the inline endsWith check fires on care-package.json. Cloudflare adapter's deploy log then prints Failed to copy <dir> for each affected directory.

Fix

Switch the inline check to a real basename comparison. The helper is exported so the regression is covered by a unit test alongside isExcluded / isNonLinuxPlatformPackage.

export function isPackageJson(modulePath: string): boolean {
  const lastSep = Math.max(
    modulePath.lastIndexOf("/"),
    modulePath.lastIndexOf("\\"),
  );
  return modulePath.slice(lastSep + 1) === "package.json";
}

path.basename was avoided because traced paths can come from either platform after path.join, and path.basename only splits on the OS-native separator. The manual scan handles both.

Tests

Added three cases in packages/tests-unit/tests/build/copyTracedFiles.test.ts:

• positive: …/next/package.json and bare package.json → true
• regression: …/care-package.json, …/my-package.json → false
• cross-platform: Windows-style \ separators behave the same

✓ packages/tests-unit/tests/build/copyTracedFiles.test.ts (12 tests) 3ms

Risk

Behavior only changes for filenames that share the package.json suffix but aren't actually package manifests. Real package.json traces continue to be picked up identically.

Changeset

Included a patch changeset under .changeset/fix-copytraced-package-json-suffix.md.

[changeset-bot]

🦋 Changeset detected

Latest commit: 646b685

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@opennextjs/aws	Patch
app-pages-router	Patch

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[sommeeeer]

LGTM!

[vicb]

I guess using path.basename could be a proper fix?

[vicb]

We should avoid using OS specific constructs as much as possible.
I don't think this is needed here.

[vicb]

Would that work instead?

Suggested change

	if (isPackageJson(module)) {
	if (path.basename(module) === "package.json") {