diff --git a/hermes_cli/oneshot.py b/hermes_cli/oneshot.py
index b79644f67..1dd24951c 100644
--- a/hermes_cli/oneshot.py
+++ b/hermes_cli/oneshot.py
@@ -191,11 +191,15 @@ def run_oneshot(
         except Exception:
             pass
 
-    if response:
-        real_stdout.write(response)
-        if not response.endswith("\n"):
-            real_stdout.write("\n")
-        real_stdout.flush()
+    if not (response or "").strip():
+        sys.stderr.write("hermes -z: no final response was produced; treating the run as failed.\n")
+        sys.stderr.flush()
+        return 1
+
+    real_stdout.write(response)
+    if not response.endswith("\n"):
+        real_stdout.write("\n")
+    real_stdout.flush()
     return 0
 
 
diff --git a/tests/hermes_cli/test_tui_resume_flow.py b/tests/hermes_cli/test_tui_resume_flow.py
index bcf552a8f..ef002c9af 100644
--- a/tests/hermes_cli/test_tui_resume_flow.py
+++ b/tests/hermes_cli/test_tui_resume_flow.py
@@ -638,6 +638,30 @@ def test_oneshot_rejects_invalid_only_toolsets(monkeypatch, capsys):
     assert "did not contain any valid toolsets" in err
 
 
+def test_oneshot_fails_closed_on_empty_final_response(monkeypatch, capsys):
+    _stub_plugin_discovery(monkeypatch)
+    import hermes_cli.oneshot as oneshot_mod
+
+    monkeypatch.setattr(oneshot_mod, "_run_agent", lambda *_args, **_kwargs: "")
+
+    assert oneshot_mod.run_oneshot("hello") == 1
+    captured = capsys.readouterr()
+    assert captured.out == ""
+    assert "no final response" in captured.err
+
+
+def test_oneshot_prints_nonempty_final_response(monkeypatch, capsys):
+    _stub_plugin_discovery(monkeypatch)
+    import hermes_cli.oneshot as oneshot_mod
+
+    monkeypatch.setattr(oneshot_mod, "_run_agent", lambda *_args, **_kwargs: "done")
+
+    assert oneshot_mod.run_oneshot("hello") == 0
+    captured = capsys.readouterr()
+    assert captured.out == "done\n"
+    assert captured.err == ""
+
+
 def test_oneshot_filters_invalid_toolsets_before_redirect(monkeypatch, capsys):
     _stub_plugin_discovery(monkeypatch)
     from hermes_cli.oneshot import _validate_explicit_toolsets