diff --git a/tests/tools/test_process_registry.py b/tests/tools/test_process_registry.py
index 6009837cd2d74..b758933e244c0 100644
--- a/tests/tools/test_process_registry.py
+++ b/tests/tools/test_process_registry.py
@@ -1649,6 +1649,10 @@ class TestSystemdCgroupIsolation:
     ENTIRE gateway cgroup, taking down the messaging control plane.
     """
 
+    @pytest.fixture(autouse=True)
+    def _mark_gateway_process(self, monkeypatch):
+        monkeypatch.setenv("_HERMES_GATEWAY", "1")
+
     def _fake_popen_capture(self):
         """Return (fake_popen, captured) where captured["argv"] gets the
         argv passed to subprocess.Popen."""
@@ -1780,6 +1784,63 @@ class TestSystemdCgroupIsolation:
         assert argv == ["/bin/bash", "-lic", "set +m; echo hello"], argv
         assert captured["start_new_session"] is True
 
+    def test_inherited_systemd_marker_does_not_scope_interactive_cli(
+        self, registry, monkeypatch
+    ):
+        """A CLI inside a supervised terminal must keep workers off its tty."""
+        fake_popen, captured = self._fake_popen_capture()
+
+        monkeypatch.setenv("INVOCATION_ID", "herdr-service-inherited-marker")
+        monkeypatch.delenv("_HERMES_GATEWAY", raising=False)
+        monkeypatch.setattr("tools.process_registry._find_shell", lambda: "/bin/bash")
+        monkeypatch.setattr(
+            "tools.process_registry._systemd_run_user_scope_available",
+            lambda: True,
+        )
+        monkeypatch.setattr("shutil.which", lambda name: "/usr/bin/systemd-run")
+
+        with patch("subprocess.Popen", side_effect=fake_popen), \
+            patch("threading.Thread", return_value=MagicMock()), \
+            patch.object(registry, "_write_checkpoint"):
+            registry.spawn_local("echo hello", cwd="/tmp")
+
+        assert captured["argv"] == [
+            "/bin/bash",
+            "-lic",
+            "set +m; echo hello",
+        ]
+        assert captured["start_new_session"] is True
+
+    def test_inherited_systemd_marker_does_not_scope_interactive_cli_pty(
+        self, registry, monkeypatch
+    ):
+        """The same gateway-identity gate applies to PTY-backed workers."""
+        from ptyprocess import PtyProcess
+
+        fake_pty = MagicMock()
+        fake_pty.pid = 4321
+
+        monkeypatch.setenv("INVOCATION_ID", "herdr-service-inherited-marker")
+        monkeypatch.delenv("_HERMES_GATEWAY", raising=False)
+        monkeypatch.setattr("tools.process_registry._find_shell", lambda: "/bin/bash")
+        monkeypatch.setattr(
+            "tools.process_registry._systemd_run_user_scope_available",
+            lambda: True,
+        )
+        monkeypatch.setattr("shutil.which", lambda name: "/usr/bin/systemd-run")
+
+        with patch.object(PtyProcess, "spawn", return_value=fake_pty) as pty_spawn, \
+            patch("threading.Thread", return_value=MagicMock()), \
+            patch.object(registry, "_write_checkpoint"):
+            session = registry.spawn_local("codex", cwd="/tmp", use_pty=True)
+
+        assert pty_spawn.call_args.args[0] == [
+            "/bin/bash",
+            "-lic",
+            "set +m; codex",
+        ]
+        assert session.systemd_unit == ""
+
     def test_systemd_post_spawn_failure_never_kills_gateway_process_group(
         self, registry, monkeypatch
     ):
diff --git a/tools/process_registry.py b/tools/process_registry.py
index a9e142eedf11c..abbf6836b489d 100644
--- a/tools/process_registry.py
+++ b/tools/process_registry.py
@@ -245,6 +245,27 @@ def _systemd_run_user_scope_available() -> bool:
         return available
 
 
+def _is_supervised_gateway_process() -> bool:
+    """Return whether this process is in a supervised Hermes gateway runtime.
+
+    Supervisor markers such as systemd's ``INVOCATION_ID`` are inherited by
+    every descendant. An interactive CLI launched from a supervised terminal
+    manager therefore cannot use that marker alone: its login-shell workers
+    would stay in the CLI's session and could take ownership of the controlling
+    tty. ``gateway.run`` adds ``_HERMES_GATEWAY`` to the gateway process tree;
+    unrelated supervised terminal managers do not.
+    """
+    if os.environ.get("_HERMES_GATEWAY") != "1":
+        return False
+
+    try:
+        from gateway.restart import is_gateway_supervisor_process
+
+        return is_gateway_supervisor_process()
+    except Exception:
+        return False
+
+
 def _build_systemd_scope_argv(
     shell_argv: List[str],
     unit_suffix: str,
@@ -991,18 +1012,12 @@ class ProcessRegistry:
                 # Cgroup isolation for PTY mode (#70716, reviewer gap #1):
                 # Wrap the PTY command in a systemd scope so interactive
                 # executors get their own cgroup, same as pipe mode.
-                pty_use_systemd_scope = False
-                try:
-                    from gateway.restart import is_gateway_supervisor_process
-
-                    pty_under_supervisor = is_gateway_supervisor_process()
-                    pty_use_systemd_scope = (
-                        not _IS_WINDOWS
-                        and pty_under_supervisor
-                        and _systemd_run_user_scope_available()
-                    )
-                except Exception:
-                    pty_use_systemd_scope = False
+                pty_under_supervisor = _is_supervised_gateway_process()
+                pty_use_systemd_scope = (
+                    not _IS_WINDOWS
+                    and pty_under_supervisor
+                    and _systemd_run_user_scope_available()
+                )
 
                 if pty_use_systemd_scope:
                     pty_argv = _build_systemd_scope_argv(
@@ -1081,18 +1096,12 @@ class ProcessRegistry:
         # for both pipe mode and the PTY path above.
         shell_argv = [user_shell, "-lic", f"set +m; {safe_command}"]
         use_systemd_scope = False
-        under_supervisor = False
-        try:
-            from gateway.restart import is_gateway_supervisor_process
-
-            under_supervisor = is_gateway_supervisor_process()
-            use_systemd_scope = (
-                not _IS_WINDOWS
-                and under_supervisor
-                and _systemd_run_user_scope_available()
-            )
-        except Exception:
-            use_systemd_scope = False
+        under_supervisor = _is_supervised_gateway_process()
+        use_systemd_scope = (
+            not _IS_WINDOWS
+            and under_supervisor
+            and _systemd_run_user_scope_available()
+        )
 
         if use_systemd_scope:
             unit_suffix = (