diff --git a/src/platforms/apple/core/__tests__/runner-macos-products.test.ts b/src/platforms/apple/core/__tests__/runner-macos-products.test.ts
new file mode 100644
index 000000000..b410159f5
--- /dev/null
+++ b/src/platforms/apple/core/__tests__/runner-macos-products.test.ts
@@ -0,0 +1,108 @@
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import path from 'node:path';
+
+import { test } from 'vitest';
+
+import { MACOS_DEVICE } from '../../../../__tests__/test-utils/device-fixtures.ts';
+import { mkdtempForTestSync } from '../../../../__tests__/test-utils/tmp-dir.ts';
+import { AppError } from '@agent-device/kernel/errors';
+import {
+  isExpectedRunnerRepairFailure,
+  repairMacOsRunnerProductsIfNeeded,
+} from '../runner/runner-macos-products.ts';
+import { createLocalAppleToolProvider, withAppleToolProvider } from '../tool-provider.ts';
+
+const XCTESTRUN_PATH = '/tmp/agent-device-runner.xctestrun';
+
+test('repair discovers and re-signs nested code before the product', async () => {
+  const { productPath, embeddedItemPaths } = createProduct();
+  const calls: string[][] = [];
+  const provider = createCodesignProvider(
+    calls,
+    (args) => args.includes('--sign') && args.at(-1) === productPath,
+  );
+
+  await withAppleToolProvider(provider, async () => {
+    await repairMacOsRunnerProductsIfNeeded(MACOS_DEVICE, [productPath], XCTESTRUN_PATH);
+  });
+
+  const signingArgs = [
+    '--force',
+    '--preserve-metadata=identifier,entitlements,flags,runtime',
+    '--sign',
+    '-',
+  ];
+  assert.deepEqual(calls.slice(1, -1), [
+    ...embeddedItemPaths.map((itemPath) => [...signingArgs, itemPath]),
+    [...signingArgs, productPath],
+  ]);
+  assert.deepEqual(calls.at(-1), ['--verify', '--deep', '--strict', productPath]);
+});
+
+test('repair fails when re-signing leaves the product unverifiable', async () => {
+  const productPath = createProductPath();
+  const provider = createCodesignProvider([], () => false);
+
+  const error = await withAppleToolProvider(
+    provider,
+    async () =>
+      await repairMacOsRunnerProductsIfNeeded(MACOS_DEVICE, [productPath], XCTESTRUN_PATH).then(
+        () => null,
+        (thrown: unknown) => thrown,
+      ),
+  );
+
+  assert.ok(error instanceof AppError);
+  assert.equal(isExpectedRunnerRepairFailure(error), true);
+});
+
+function createProductPath(): string {
+  return createProduct().productPath;
+}
+
+function createProduct(): {
+  productPath: string;
+  embeddedItemPaths: string[];
+} {
+  const root = mkdtempForTestSync('agent-device-runner-products-');
+  const productPath = path.join(root, 'AgentDeviceRunnerUITests-Runner.app');
+  fs.mkdirSync(productPath);
+  const frameworksRoot = path.join(productPath, 'Contents', 'Frameworks');
+  const embeddedItemPaths = [
+    'FutureTestSupport.framework',
+    'AnotherTestSupport.framework',
+    'libFutureTestSupport.dylib',
+  ].map((itemName) => path.join(frameworksRoot, itemName));
+  for (const itemPath of embeddedItemPaths) {
+    if (itemPath.endsWith('.framework')) {
+      fs.mkdirSync(itemPath, { recursive: true });
+    } else {
+      fs.mkdirSync(path.dirname(itemPath), { recursive: true });
+      fs.writeFileSync(itemPath, '');
+    }
+  }
+  return { productPath, embeddedItemPaths: embeddedItemPaths.sort() };
+}
+
+function createCodesignProvider(
+  calls: string[][],
+  isRepairingSignature: (args: readonly string[]) => boolean,
+) {
+  let repaired = false;
+  return createLocalAppleToolProvider({
+    runCommand: async (command, args = []) => {
+      assert.equal(command, 'codesign');
+      calls.push([...args]);
+      if (isRepairingSignature(args)) {
+        repaired = true;
+      }
+      const verifying = args[0] === '--verify';
+      return {
+        exitCode: verifying && !repaired ? 1 : 0,
+        stdout: '',
+        stderr: '',
+      };
+    },
+  });
+}
diff --git a/src/platforms/apple/core/runner/runner-macos-products.ts b/src/platforms/apple/core/runner/runner-macos-products.ts
index b3e177df2..bf5c578d2 100644
--- a/src/platforms/apple/core/runner/runner-macos-products.ts
+++ b/src/platforms/apple/core/runner/runner-macos-products.ts
@@ -1,4 +1,5 @@
 import fs from 'node:fs';
+import path from 'node:path';
 import { isMacOs, type DeviceInfo } from '@agent-device/kernel/device';
 import { AppError, asAppError } from '@agent-device/kernel/errors';
 import { runAppleToolCommand } from '../tool-provider.ts';
@@ -8,6 +9,14 @@ const RUNNER_PRODUCT_REPAIR_FAILURE_REASONS = new Set([
   'RUNNER_PRODUCT_REPAIR_FAILED',
 ]);
 
+const AD_HOC_RESIGN_ARGS = [
+  '--force',
+  // Designated requirements must be regenerated for the ad-hoc identity.
+  '--preserve-metadata=identifier,entitlements,flags,runtime',
+  '--sign',
+  '-',
+] as const;
+
 export async function repairMacOsRunnerProductsIfNeeded(
   device: DeviceInfo,
   productPaths: string[],
@@ -39,24 +48,52 @@ export async function repairMacOsRunnerProductsIfNeeded(
     if (await hasValidCodeSignature(productPath)) {
       continue;
     }
-    await runAppleToolCommand('codesign', ['--remove-signature', productPath], {
-      allowFailure: true,
-    });
-    try {
-      await runAppleToolCommand('codesign', ['--force', '--sign', '-', productPath]);
-    } catch (error) {
-      const appError = asAppError(error, 'COMMAND_FAILED');
-      throw new AppError('COMMAND_FAILED', 'Failed to repair macOS runner product signature', {
-        reason: 'RUNNER_PRODUCT_REPAIR_FAILED',
-        productPath,
-        xctestrunPath,
-        error: appError.message,
-        details: appError.details,
-      });
+    await resignRunnerProduct(productPath, xctestrunPath);
+  }
+}
+
+async function resignRunnerProduct(productPath: string, xctestrunPath: string): Promise<void> {
+  try {
+    const frameworksPath = path.join(productPath, 'Contents', 'Frameworks');
+    const embeddedCodePaths = fs.existsSync(frameworksPath)
+      ? fs
+          .readdirSync(frameworksPath)
+          .sort()
+          .map((itemName) => path.join(frameworksPath, itemName))
+      : [];
+    for (const embeddedCodePath of embeddedCodePaths) {
+      await runAppleToolCommand('codesign', [...AD_HOC_RESIGN_ARGS, embeddedCodePath]);
     }
+    await runAppleToolCommand('codesign', [...AD_HOC_RESIGN_ARGS, productPath]);
+  } catch (error) {
+    const appError = asAppError(error, 'COMMAND_FAILED');
+    throw repairFailure(productPath, xctestrunPath, appError.message, appError.details);
+  }
+
+  if (!(await hasValidCodeSignature(productPath))) {
+    throw repairFailure(
+      productPath,
+      xctestrunPath,
+      'Product still fails code signature verification after re-signing',
+    );
   }
 }
 
+function repairFailure(
+  productPath: string,
+  xctestrunPath: string,
+  error: string,
+  details?: unknown,
+): AppError {
+  return new AppError('COMMAND_FAILED', 'Failed to repair macOS runner product signature', {
+    reason: 'RUNNER_PRODUCT_REPAIR_FAILED',
+    productPath,
+    xctestrunPath,
+    error,
+    details,
+  });
+}
+
 export function isExpectedRunnerRepairFailure(error: unknown): boolean {
   if (!(error instanceof AppError)) {
     return false;