diff --git a/packages/mcp/scripts/smoke-package.mjs b/packages/mcp/scripts/smoke-package.mjs
index 0b122b3..1b18ce2 100644
--- a/packages/mcp/scripts/smoke-package.mjs
+++ b/packages/mcp/scripts/smoke-package.mjs
@@ -10,6 +10,10 @@ import { Client } from "@modelcontextprotocol/sdk/client/index.js";
 import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";
 
 import { buildStandaloneMcpPackage } from "./build-package-lib.mjs";
+import {
+  findSingleTarball,
+  normalizePackedTarEntries,
+} from "../../../scripts/root-release-guard.mjs";
 
 const REQUIRED_TOOLS = [
   "martin_doctor",
@@ -78,21 +82,16 @@ export async function runStandaloneMcpSmoke(options = {}) {
   try {
     await buildStandaloneMcpPackage({ packageDir });
 
-    const packDryRun = await runCommand(npmCommand(), ["pack", "--ignore-scripts", "--json", "--dry-run"], {
-      cwd: packageDir,
-    });
-    const dryRunEntry = parsePackEntry(packDryRun.stdout);
-    const tarballFiles = dryRunEntry.files.map((file) => file.path).sort();
-    assertTarballFileSet(tarballFiles);
-
-    const packRun = await runCommand(
+    await runCommand(
       npmCommand(),
-      ["pack", "--ignore-scripts", "--json", "--pack-destination", packDir],
+      ["pack", "--ignore-scripts", "--pack-destination", packDir],
       { cwd: packageDir },
     );
-    const packEntry = parsePackEntry(packRun.stdout);
-    const tarballFilename = packEntry.filename;
-    const tarballPath = path.join(packDir, packEntry.filename);
+    const tarballFilename = await findSingleTarball(packDir);
+    const tarballPath = path.join(packDir, tarballFilename);
+    const tarList = await runCommand(tarCommand(), ["-tf", tarballFilename], { cwd: packDir });
+    const tarballFiles = normalizePackedTarEntries(tarList.stdout.split(/\r?\n/u)).sort();
+    assertTarballFileSet(tarballFiles);
 
     const [packedManifestOutput, packedServerOutput] = await Promise.all([
       runCommand(
@@ -302,15 +301,6 @@ function readTextContent(result) {
   return first.text;
 }
 
-function parsePackEntry(stdout) {
-  const parsed = JSON.parse(stdout);
-  const entry = Array.isArray(parsed) ? parsed[0] : null;
-  if (!entry || typeof entry.filename !== "string" || !Array.isArray(entry.files)) {
-    throw new Error("npm pack did not return a usable pack result.");
-  }
-  return entry;
-}
-
 function npmCommand() {
   return process.platform === "win32" ? "npm.cmd" : "npm";
 }
diff --git a/scripts/pack-root-release.mjs b/scripts/pack-root-release.mjs
index 140b08a..21b7c9b 100644
--- a/scripts/pack-root-release.mjs
+++ b/scripts/pack-root-release.mjs
@@ -6,23 +6,18 @@ import path from "node:path";
 import { fileURLToPath } from "node:url";
 
 import { resolveRcCommandExecution } from "./rc-validation.mjs";
-import { extractPackJsonPayload } from "./root-release-guard.mjs";
+import { findSingleTarball } from "./root-release-guard.mjs";
 
 export async function packRootRelease(options = {}) {
   const rootDir = options.rootDir ?? process.cwd();
   const outputDir = path.resolve(rootDir, options.outputDir ?? "dist-release");
   await mkdir(outputDir, { recursive: true });
 
-  const packRun = await runCommand(
-    ["npm", "pack", "--json", "--pack-destination", outputDir],
+  await runCommand(
+    ["npm", "pack", "--pack-destination", outputDir],
     { cwd: rootDir },
   );
-  const packArtifacts = extractPackJsonPayload(packRun.stdout);
-  const tarballName = Array.isArray(packArtifacts) ? packArtifacts[0]?.filename : null;
-
-  if (typeof tarballName !== "string" || tarballName.length === 0) {
-    throw new Error("npm pack did not return a tarball filename.");
-  }
+  const tarballName = await findSingleTarball(outputDir);
 
   return {
     outputDir,
diff --git a/scripts/public-facade-smoke.mjs b/scripts/public-facade-smoke.mjs
index 16c72ce..91446ea 100644
--- a/scripts/public-facade-smoke.mjs
+++ b/scripts/public-facade-smoke.mjs
@@ -9,7 +9,7 @@ import { fileURLToPath } from "node:url";
 import { resolveRcCommandExecution } from "./rc-validation.mjs";
 import {
   assertPackedSurface,
-  extractPackJsonPayload,
+  findSingleTarball,
   inspectPackedFiles,
 } from "./root-release-guard.mjs";
 
@@ -56,16 +56,10 @@ export async function runPublicFacadeSmoke(options = {}) {
   await mkdir(appDir, { recursive: true });
 
   try {
-    const packRun = await runCommand(["npm", "pack", "--json", "--ignore-scripts", "--pack-destination", packDir], {
+    await runCommand(["npm", "pack", "--ignore-scripts", "--pack-destination", packDir], {
       cwd: rootDir,
     });
-    const packArtifacts = extractPackJsonPayload(packRun.stdout);
-    const tarballName = Array.isArray(packArtifacts) ? packArtifacts[0]?.filename : undefined;
-
-    if (typeof tarballName !== "string" || tarballName.trim().length === 0) {
-      throw new Error("npm pack did not return a tarball filename.");
-    }
-
+    const tarballName = await findSingleTarball(packDir);
     const tarballPath = path.join(packDir, tarballName);
     await writeFile(
       path.join(appDir, "package.json"),
diff --git a/scripts/root-release-guard.mjs b/scripts/root-release-guard.mjs
index c0b0cef..78ebaae 100644
--- a/scripts/root-release-guard.mjs
+++ b/scripts/root-release-guard.mjs
@@ -114,13 +114,10 @@ export async function inspectPackedFiles(options = {}) {
     }
     await runCommand(command, { cwd: rootDir });
 
-    const tarballs = (await readdir(packDestination)).filter((entry) => entry.endsWith(".tgz"));
-    if (tarballs.length !== 1) {
-      throw new Error(`npm pack produced ${tarballs.length} tarballs; expected exactly one.`);
-    }
+    const tarballName = await findSingleTarball(packDestination);
 
     const tarRun = await runCommand(
-      ["tar", "-tf", path.join(packDestination, tarballs[0])],
+      ["tar", "-tf", path.join(packDestination, tarballName)],
       { cwd: rootDir },
     );
     const files = normalizePackedTarEntries(tarRun.stdout.split(/\r?\n/u));
@@ -134,6 +131,14 @@ export async function inspectPackedFiles(options = {}) {
   }
 }
 
+export async function findSingleTarball(directory) {
+  const tarballs = (await readdir(directory)).filter((entry) => entry.endsWith(".tgz"));
+  if (tarballs.length !== 1) {
+    throw new Error(`npm pack produced ${tarballs.length} tarballs; expected exactly one.`);
+  }
+  return tarballs[0];
+}
+
 export function normalizePackedTarEntries(entries) {
   return entries
     .map((entry) => entry.trim().replace(/^package\//u, ""))
diff --git a/scripts/tests/root-release-guard.test.mjs b/scripts/tests/root-release-guard.test.mjs
index d852b69..e87d081 100644
--- a/scripts/tests/root-release-guard.test.mjs
+++ b/scripts/tests/root-release-guard.test.mjs
@@ -10,6 +10,7 @@ import {
   assertRootVersionPolicy,
   assertVendoredCliManifest,
   extractPackFilePaths,
+  findSingleTarball,
   normalizePackedTarEntries,
   runRootReleaseGuard,
 } from "../root-release-guard.mjs";
@@ -110,6 +111,14 @@ test("normalizePackedTarEntries reads the real npm tarball surface", () => {
   );
 });
 
+test("findSingleTarball discovers the real npm pack artifact", async () => {
+  await withTempRoot(async (tempRoot) => {
+    await writeFile(path.join(tempRoot, "martin-loop-0.5.0.tgz"), "artifact", "utf8");
+
+    assert.equal(await findSingleTarball(tempRoot), "martin-loop-0.5.0.tgz");
+  });
+});
+
 test("assertVendoredCliManifest accepts the sanitized vendored CLI package manifest", async () => {
   await withTempRoot(async (tempRoot) => {
     await writeFile(