fix: add TTY guard to interactive CLI commands to prevent CPU spin (#3933)

When interactive TUI commands are invoked non-interactively (e.g. via
the agent's terminal() tool through a subprocess pipe), curses loops
spin at 100% CPU and input() calls hang indefinitely.

Defense in depth — two layers:

1. Source-level guard in curses_checklist() (curses_ui.py + checklist.py):
   Returns cancel_returns immediately when stdin is not a TTY. This
   catches ALL callers automatically, including future code.

2. Command-level guards with clear error messages:
   - hermes tools (interactive checklist, not list/disable/enable)
   - hermes setup (interactive wizard)
   - hermes model (provider/model picker)
   - hermes whatsapp (pairing setup)
   - hermes skills config (skill toggle)
   - hermes mcp configure (tool selection)
   - hermes uninstall (confirmation prompt)

Non-interactive subcommands (hermes tools list, hermes tools enable,
hermes mcp add/remove/list/test, hermes skills search/install/browse)
remain unaffected.

hermes_cli/checklist.py

@@ -5,6 +5,7 @@ toggleable list of items.  Falls back to a numbered text UI when
 curses is unavailable (Windows without curses, piped stdin, etc.).
 """
 
+import sys
 from typing import List, Set
 
 from hermes_cli.colors import Colors, color
@@ -26,6 +27,10 @@ def curses_checklist(
         The indices the user confirmed as checked.  On cancel (ESC/q),
         returns ``pre_selected`` unchanged.
     """
+    # Safety: return defaults when stdin is not a terminal.
+    if not sys.stdin.isatty():
+        return set(pre_selected)
+
     try:
         import curses
         selected = set(pre_selected)

hermes_cli/curses_ui.py

@@ -4,6 +4,7 @@ Used by `hermes tools` and `hermes skills` for interactive checklists.
 Provides a curses multi-select with keyboard navigation, plus a
 text-based numbered fallback for terminals without curses support.
 """
+import sys
 from typing import Callable, List, Optional, Set
 
 from hermes_cli.colors import Colors, color
@@ -31,6 +32,11 @@ def curses_checklist(
     if cancel_returns is None:
         cancel_returns = set(selected)
 
+    # Safety: curses and input() both hang or spin when stdin is not a
+    # terminal (e.g. subprocess pipe).  Return defaults immediately.
+    if not sys.stdin.isatty():
+        return cancel_returns
+
     try:
         import curses
         chosen = set(selected)

hermes_cli/main.py

@@ -50,6 +50,23 @@ import sys
 from pathlib import Path
 from typing import Optional
 
+def _require_tty(command_name: str) -> None:
+    """Exit with a clear error if stdin is not a terminal.
+
+    Interactive TUI commands (hermes tools, hermes setup, hermes model) use
+    curses or input() prompts that spin at 100% CPU when stdin is a pipe.
+    This guard prevents accidental non-interactive invocation.
+    """
+    if not sys.stdin.isatty():
+        print(
+            f"Error: 'hermes {command_name}' requires an interactive terminal.\n"
+            f"It cannot be run through a pipe or non-interactive subprocess.\n"
+            f"Run it directly in your terminal instead.",
+            file=sys.stderr,
+        )
+        sys.exit(1)
+
+
 # Add project root to path
 PROJECT_ROOT = Path(__file__).parent.parent.resolve()
 sys.path.insert(0, str(PROJECT_ROOT))
@@ -617,6 +634,7 @@ def cmd_gateway(args):
 
 def cmd_whatsapp(args):
     """Set up WhatsApp: choose mode, configure, install bridge, pair via QR."""
+    _require_tty("whatsapp")
     import subprocess
     from pathlib import Path
     from hermes_cli.config import get_env_value, save_env_value
@@ -803,12 +821,14 @@ def cmd_whatsapp(args):
 
 def cmd_setup(args):
     """Interactive setup wizard."""
+    _require_tty("setup")
     from hermes_cli.setup import run_setup_wizard
     run_setup_wizard(args)
 
 
 def cmd_model(args):
     """Select default model — starts with provider selection, then model picker."""
+    _require_tty("model")
     from hermes_cli.auth import (
         resolve_provider, AuthError, format_auth_error,
     )
@@ -2459,6 +2479,7 @@ def cmd_version(args):
 
 def cmd_uninstall(args):
     """Uninstall Hermes Agent."""
+    _require_tty("uninstall")
     from hermes_cli.uninstall import run_uninstall
     run_uninstall(args)
 
@@ -4131,6 +4152,7 @@ For more help on a command:
     def cmd_skills(args):
         # Route 'config' action to skills_config module
         if getattr(args, 'skills_action', None) == 'config':
+            _require_tty("skills config")
             from hermes_cli.skills_config import skills_command as skills_config_command
             skills_config_command(args)
         else:
@@ -4341,6 +4363,7 @@ For more help on a command:
             from hermes_cli.tools_config import tools_disable_enable_command
             tools_disable_enable_command(args)
         else:
+            _require_tty("tools")
             from hermes_cli.tools_config import tools_command
             tools_command(args)
 

hermes_cli/mcp_config.py

@@ -511,6 +511,10 @@ def _interpolate_value(value: str) -> str:
 
 def cmd_mcp_configure(args):
     """Reconfigure which tools are enabled for an existing MCP server."""
+    import sys as _sys
+    if not _sys.stdin.isatty():
+        print("Error: 'hermes mcp configure' requires an interactive terminal.", file=_sys.stderr)
+        _sys.exit(1)
     name = args.name
     servers = _get_mcp_servers()