diff --git a/hermes_cli/setup.py b/hermes_cli/setup.py
index a4c089b9aa25a..a8a4facaca614 100644
--- a/hermes_cli/setup.py
+++ b/hermes_cli/setup.py
@@ -2924,6 +2924,13 @@ def run_setup_wizard(args):
 
 def _offer_launch_chat():
     """Prompt the user to jump straight into chat after setup."""
+    # Guard: chat requires interactive TTY (prompt_toolkit)
+    if not is_interactive_stdin():
+        print_noninteractive_setup_guidance(
+            "Chat mode requires an interactive terminal. "
+            "Run 'hermes chat' directly in your terminal to start."
+        )
+        return
     print()
     if prompt_yes_no("Launch hermes chat now?", True):
         from hermes_cli.main import cmd_chat