diff --git a/docs/release-control/v6/internal/subsystems/deployment-installability.md b/docs/release-control/v6/internal/subsystems/deployment-installability.md
index 89e7110d7..dbcd4eacf 100644
--- a/docs/release-control/v6/internal/subsystems/deployment-installability.md
+++ b/docs/release-control/v6/internal/subsystems/deployment-installability.md
@@ -2145,6 +2145,17 @@ artifact-selection behaviour.
     secrets, and seed hosted approvals through a single explicit tenant runtime
     restart when a release proof needs transactionally visible approval state.
 
+   Browser execution must invoke the npm-ci-installed
+   `/work/node_modules/@playwright/test/cli.js` directly with Node inside the
+   selected Playwright image. Missing or inaccessible mounted dependencies
+   must fail admission rather than trigger an npx registry download of a
+   substitute runner. Preserve the existing container UID/GID, mount, image
+   version selection and exit status. The executed-shell fixture in
+   `scripts/release_control/internal/release_preflight_test.py` verifies the
+   runner path, argument quoting, container identity and failure propagation
+   with mocked Docker; it is not browser qualification or proof that the
+   retained spawn-sh EACCES failure has been repaired.
+
 ## Forbidden Paths
 
 1. Leaving deployment bootstrap, installer, or update-runtime files unowned under broad monitoring or generic API ownership
diff --git a/scripts/release-preflight-worker.sh b/scripts/release-preflight-worker.sh
index ed9166e4f..19a859e96 100755
--- a/scripts/release-preflight-worker.sh
+++ b/scripts/release-preflight-worker.sh
@@ -257,6 +257,9 @@ else
     --tag pulse:test \
     .
 fi
+# Use only the npm-ci-installed runner. npx may fetch a different version when
+# the mounted dependency tree is missing or inaccessible, masking the actual
+# admission failure and breaking parity with the selected browser image.
 run_playwright() {
   docker run --rm \
     --network host \
@@ -269,7 +272,7 @@ run_playwright() {
     --volume "$REPOSITORY_DIR/tests/integration:/work" \
     --workdir /work \
     "$PLAYWRIGHT_IMAGE" \
-    npx playwright test "$@"
+    node /work/node_modules/@playwright/test/cli.js test "$@"
 }
 
 run_rehearsal_smoke() {
diff --git a/scripts/release_control/internal/release_preflight_test.py b/scripts/release_control/internal/release_preflight_test.py
index 0c2cc4950..d8ef5ea87 100755
--- a/scripts/release_control/internal/release_preflight_test.py
+++ b/scripts/release_control/internal/release_preflight_test.py
@@ -264,6 +264,39 @@ class ReleasePreflightTest(unittest.TestCase):
         self.assertIn('--env "PLAYWRIGHT_BASE_URL=${PULSE_E2E_BASE_URL}"', worker)
         self.assertNotIn("localhost:7655", worker)
 
+    def test_browser_uses_installed_runner_and_preserves_failure(self) -> None:
+        worker = (ROOT / "scripts/release-preflight-worker.sh").read_text()
+        function = re.search(
+            r"run_playwright\(\) \{.*?\n\}", worker, flags=re.DOTALL
+        ).group(0)
+        # Exercise the real shell function without starting Docker or a browser.
+        # A failed container must propagate, not become a successful admission.
+        for status in (0, 13):
+            with self.subTest(status=status):
+                result = subprocess.run(
+                    ["bash", "-c", """
+docker() { printf '%s\n' "$@"; return """ + str(status) + """; }
+REPOSITORY_DIR='/tmp/worker with spaces/repo'
+PLAYWRIGHT_IMAGE='mcr.microsoft.com/playwright:v1.61.1-noble'
+PULSE_E2E_BASE_URL='http://localhost:27655'
+""" + function + """
+run_playwright 'tests/a test.spec.ts' --project=chromium
+"""],
+                    text=True, capture_output=True, check=False,
+                )
+                self.assertEqual(result.returncode, status, result.stderr)
+                args = result.stdout.splitlines()
+                self.assertEqual(args[-5:], [
+                    "node", "/work/node_modules/@playwright/test/cli.js",
+                    "test", "tests/a test.spec.ts", "--project=chromium",
+                ])
+                self.assertNotIn("npx", args)
+                self.assertEqual(args[args.index("--volume") + 1],
+                                 "/tmp/worker with spaces/repo/tests/integration:/work")
+                self.assertEqual(args[args.index("--user") + 1],
+                                 f"{os.getuid()}:{os.getgid()}")
+                self.assertIn("mcr.microsoft.com/playwright:v1.61.1-noble", args)
+
     def test_worker_serializes_resource_intensive_test_suites(self) -> None:
         worker = (ROOT / "scripts/release-preflight-worker.sh").read_text()
         scheduling_block = re.search(