Fix npm pack JSON release validation

scripts/root-release-guard.mjs

@@ -113,9 +113,7 @@ export async function inspectPackedFiles(options = {}) {
     { cwd: rootDir },
   );
   const packArtifacts = extractPackJsonPayload(packRun.stdout);
-  const files = Array.isArray(packArtifacts)
-    ? packArtifacts[0]?.files?.map((entry) => entry.path).filter((entry) => typeof entry === "string")
-    : [];
+  const files = extractPackFilePaths(packArtifacts);
 
   if (files.length === 0) {
     throw new Error("npm pack --dry-run did not report any packaged files.");
@@ -131,6 +129,13 @@ export function extractPackJsonPayload(stdout) {
   return JSON.parse(jsonPayload);
 }
 
+export function extractPackFilePaths(packArtifacts) {
+  const artifact = Array.isArray(packArtifacts) ? packArtifacts[0] : packArtifacts;
+  return Array.isArray(artifact?.files)
+    ? artifact.files.map((entry) => entry.path).filter((entry) => typeof entry === "string")
+    : [];
+}
+
 export async function assertVendoredCliManifest(rootDir) {
   const manifestPath = path.join(rootDir, "dist", "vendor", "cli", "package.json");
   const rootManifest = JSON.parse(await readFile(path.join(rootDir, "package.json"), "utf8"));

scripts/tests/root-release-guard.test.mjs

@@ -9,6 +9,7 @@ import {
   assertPackedSurface,
   assertRootVersionPolicy,
   assertVendoredCliManifest,
+  extractPackFilePaths,
   runRootReleaseGuard,
 } from "../root-release-guard.mjs";
 
@@ -85,6 +86,16 @@ test("assertPackedSurface rejects forbidden vendored implementation paths", () =
   );
 });
 
+test("extractPackFilePaths accepts npm pack object and array envelopes", () => {
+  const artifact = {
+    filename: "martin-loop-0.5.0.tgz",
+    files: [{ path: "package.json" }, { path: "dist/index.js" }],
+  };
+
+  assert.deepEqual(extractPackFilePaths([artifact]), ["package.json", "dist/index.js"]);
+  assert.deepEqual(extractPackFilePaths(artifact), ["package.json", "dist/index.js"]);
+});
+
 test("assertVendoredCliManifest accepts the sanitized vendored CLI package manifest", async () => {
   await withTempRoot(async (tempRoot) => {
     await writeFile(