feat(agent): enhance configuration safety and multiline command handling

- Add explicit AAA/password configuration prohibition to safety reminders
- Implement multiline command expansion for banner and similar commands
- Add error handling for devices with missing device_type tags
- Improve logging for configuration errors and multiline expansions

gns3server/agent/gns3_copilot/prompts/lab_automation_assistant_prompt.py

@@ -165,6 +165,7 @@ vlan 10
 # SAFETY REMINDERS
 
 While you have configuration permissions, exercise caution:
+- ⚠️ **FORBIDDEN**: AAA/password config (enable secret, username, aaa new-model, service password-encryption, line vty) - Provide guidance only
 - ⚠️ Avoid destructive commands (reload, erase, format) unless explicitly requested
 - ⚠️ Warn user before making major changes
 - ⚠️ Recommend backup for critical configurations

gns3server/agent/gns3_copilot/tools_v2/config_tools_nornir.py

@@ -196,6 +196,13 @@ class ExecuteMultipleDeviceConfigCommands(BaseTool):
             )
         )
 
+        # Expand multiline commands (e.g., banner commands with embedded newlines)
+        # This converts commands like "banner motd #\nline1\nline2\n#" into
+        # separate commands: ["banner motd #", "line1", "line2", "#"]
+        device_configs_list = self._expand_multiline_commands(
+            device_configs_list
+        )
+
         # Create a mapping of device names to their configuration commands
         device_configs_map = self._configs_map(device_configs_list)
 
@@ -208,6 +215,26 @@ class ExecuteMultipleDeviceConfigCommands(BaseTool):
             logger.error("Failed to prepare device hosts data: %s", e)
             return [{"error": str(e)}]
 
+        # Check if any devices have errors (e.g., missing device_type tag)
+        error_devices = {
+            name: data
+            for name, data in hosts_data.items()
+            if "error" in data
+        }
+        if error_devices:
+            logger.error(
+                "Devices with configuration errors: %s",
+                list(error_devices.keys())
+            )
+            return [
+                {
+                    "device_name": name,
+                    "status": "failed",
+                    "error": data["error"]
+                }
+                for name, data in error_devices.items()
+            ]
+
         # Initialize Nornir
         try:
             dynamic_nr = self._initialize_nornir(hosts_data)
@@ -445,6 +472,60 @@ class ExecuteMultipleDeviceConfigCommands(BaseTool):
 
         return filtered_list, blocked_commands_map
 
+    def _expand_multiline_commands(
+        self, device_configs_list: list[dict[str, Any]]
+    ) -> list[dict[str, Any]]:
+        """
+        Expand commands that contain embedded newline characters.
+
+        Some commands (like banner) are passed as single strings with embedded
+        newlines. This method splits them into separate commands for proper
+        execution by netmiko_send_config.
+
+        Note: netmiko_send_config automatically handles entering config mode,
+        so any config mode entry commands (configure terminal, system-view, etc.)
+        are left as-is and will be safely ignored by the device.
+
+        Example:
+            Input:  ["banner motd #\nline1\nline2\n#", "exit"]
+            Output: ["banner motd #", "line1", "line2", "#", "exit"]
+
+        Args:
+            device_configs_list: List of device configs with config_commands.
+
+        Returns:
+            List of device configs with multiline commands expanded.
+        """
+        expanded_list = []
+
+        for device_config in device_configs_list:
+            device_name = device_config["device_name"]
+            config_commands = device_config["config_commands"]
+
+            expanded_commands = []
+            for cmd in config_commands:
+                # Check if command contains embedded newlines
+                if "\n" in cmd:
+                    # Split by newline and expand
+                    lines = cmd.split("\n")
+                    # Filter out empty lines but keep all content lines
+                    expanded_commands.extend([line for line in lines if line.strip()])
+                    logger.info(
+                        "Device %s: Expanded multiline command (%d lines)",
+                        device_name,
+                        len(lines),
+                    )
+                else:
+                    # Keep single-line commands as-is
+                    expanded_commands.append(cmd)
+
+            # Create updated device config
+            expanded_config = device_config.copy()
+            expanded_config["config_commands"] = expanded_commands
+            expanded_list.append(expanded_config)
+
+        return expanded_list
+
     def _configs_map(
         self, device_config_list: list[dict[str, Any]]
     ) -> dict[str, list[str]]:

gns3server/agent/gns3_copilot/tools_v2/display_tools_nornir.py

@@ -211,6 +211,26 @@ class ExecuteMultipleDeviceCommands(BaseTool):
             logger.error("Failed to prepare device hosts data: %s", e)
             return [{"error": str(e)}]
 
+        # Check if any devices have errors (e.g., missing device_type tag)
+        error_devices = {
+            name: data
+            for name, data in hosts_data.items()
+            if "error" in data
+        }
+        if error_devices:
+            logger.error(
+                "Devices with configuration errors: %s",
+                list(error_devices.keys())
+            )
+            return [
+                {
+                    "device_name": name,
+                    "status": "failed",
+                    "error": data["error"]
+                }
+                for name, data in error_devices.items()
+            ]
+
         # Initialize Nornir
         try:
             dynamic_nr = self._initialize_nornir(hosts_data)

gns3server/agent/gns3_copilot/utils/get_gns3_device_port.py

@@ -104,20 +104,25 @@ def get_device_ports_from_topology(
                 elif tag.startswith("platform:"):
                     platform = tag.split(":", 1)[1].strip()
 
-            # Use defaults if not found in tags
+            # Return error if device_type not found in tags
+            # Using a default would cause command execution errors
             if device_type is None:
-                device_type = "cisco_ios_telnet"
-                logger.debug(
-                    "Device '%s': device_type not found in tags, using default: "
-                    "cisco_ios_telnet",
-                    device_name,
-                )
-            else:
-                logger.debug(
-                    "Device '%s': extracted device_type=%s from tags",
-                    device_name,
-                    device_type,
+                error_msg = (
+                    f"Device '{device_name}': device_type tag not found. "
+                    f"Please add 'device_type:<type>' tag to this device in GNS3. "
+                    f"Current tags: {tags}"
                 )
+                logger.error(error_msg)
+                hosts_data[device_name] = {
+                    "error": error_msg
+                }
+                continue
+
+            logger.debug(
+                "Device '%s': extracted device_type=%s from tags",
+                device_name,
+                device_type,
+            )
 
             if platform is None:
                 platform = "cisco_ios"