Bugfix: adding check on missing rosapi services to avoid crashes in older versions (#182)

* Check rosapi required services for action-related tools and throw error/warning if not available (applies to ROS 1 or ROS 2 Humble)
* Improved return messages for action-related tools when required services are not compatible

Author: stex2005

server.py

@@ -2073,6 +2073,45 @@ def get_actions() -> dict:
         dict: Contains list of all active actions,
             or a message string if no actions are found.
     """
+    # Check if required service is available
+    required_services = ["/rosapi/action_servers"]
+
+    with ws_manager:
+        # Get available services to check compatibility
+        services_message = {
+            "op": "call_service",
+            "service": "/rosapi/services",
+            "type": "rosapi/Services",
+            "args": {},
+            "id": "check_services_for_get_actions",
+        }
+
+        services_response = ws_manager.request(services_message)
+        if not services_response or not isinstance(services_response, dict):
+            return {
+                "warning": "Cannot check service availability",
+                "compatibility": {
+                    "issue": "Cannot determine available services",
+                    "required_services": required_services,
+                    "suggestion": "Ensure rosbridge is running and rosapi is available",
+                },
+            }
+
+        available_services = services_response.get("values", {}).get("services", [])
+        missing_services = [svc for svc in required_services if svc not in available_services]
+
+        if missing_services:
+            return {
+                "warning": "Action listing not supported by this rosbridge/rosapi version",
+                "compatibility": {
+                    "issue": "Required action services are not available",
+                    "missing_services": missing_services,
+                    "required_services": required_services,
+                    "available_services": [s for s in available_services if "action" in s],
+                    "suggestion": "This rosbridge version doesn't support action listing services",
+                },
+            }
+
     # rosbridge service call to get action list
     message = {
         "op": "call_service",
@@ -2127,6 +2166,47 @@ def get_action_type(action: str) -> dict:
     if not action or not action.strip():
         return {"error": "Action name cannot be empty"}
 
+    # Check if required service is available
+    required_services = ["/rosapi/interfaces"]
+
+    with ws_manager:
+        # Get available services to check compatibility
+        services_message = {
+            "op": "call_service",
+            "service": "/rosapi/services",
+            "type": "rosapi/Services",
+            "args": {},
+            "id": "check_services_for_get_action_type",
+        }
+
+        services_response = ws_manager.request(services_message)
+        if not services_response or not isinstance(services_response, dict):
+            return {
+                "warning": "Cannot check service availability",
+                "action": action,
+                "compatibility": {
+                    "issue": "Cannot determine available services",
+                    "required_services": required_services,
+                    "suggestion": "Ensure rosbridge is running and rosapi is available",
+                },
+            }
+
+        available_services = services_response.get("values", {}).get("services", [])
+        missing_services = [svc for svc in required_services if svc not in available_services]
+
+        if missing_services:
+            return {
+                "warning": "Action type resolution not supported by this rosbridge/rosapi version",
+                "action": action,
+                "compatibility": {
+                    "issue": "Required services are not available",
+                    "missing_services": missing_services,
+                    "required_services": required_services,
+                    "available_services": [s for s in available_services if "interface" in s],
+                    "suggestion": "This rosbridge version doesn't support interface listing services",
+                },
+            }
+
     # Since there's no direct action_type service, we'll derive it from known patterns
     # or use a mapping approach for common actions
 
@@ -2173,7 +2253,16 @@ def get_action_type(action: str) -> dict:
             "suggestion": "This action might not be available or use a different naming pattern",
         }
 
-    return {"error": f"Failed to get type for action {action}"}
+    return {
+        "error": f"Failed to get type for action {action}",
+        "action": action,
+        "compatibility": {
+            "issue": "Failed to retrieve interfaces from rosapi",
+            "required_services": ["/rosapi/interfaces"],
+            "suggestion": "Ensure rosbridge is running and rosapi is available",
+            "note": "Action type resolution requires /rosapi/interfaces service",
+        },
+    }
 
 
 @mcp.tool(
@@ -2197,6 +2286,57 @@ def get_action_details(action_type: str) -> dict:
     if not action_type or not action_type.strip():
         return {"error": "Action type cannot be empty"}
 
+    # Check if required action detail services are available
+    required_services = [
+        "/rosapi/action_goal_details",
+        "/rosapi/action_result_details",
+        "/rosapi/action_feedback_details",
+    ]
+
+    with ws_manager:
+        # Get available services to check compatibility
+        services_message = {
+            "op": "call_service",
+            "service": "/rosapi/services",
+            "type": "rosapi/Services",
+            "args": {},
+            "id": "check_services_for_action_details",
+        }
+
+        services_response = ws_manager.request(services_message)
+        if not services_response or not isinstance(services_response, dict):
+            return {
+                "error": "Failed to check service availability",
+                "action_type": action_type,
+                "compatibility": {
+                    "issue": "Cannot determine available services",
+                    "required_services": required_services,
+                    "suggestion": "Ensure rosbridge is running and rosapi is available",
+                },
+            }
+
+        available_services = services_response.get("values", {}).get("services", [])
+        missing_services = [svc for svc in required_services if svc not in available_services]
+
+        if missing_services:
+            return {
+                "error": f"Action details for {action_type} not found",
+                "action_type": action_type,
+                "compatibility": {
+                    "issue": "Required action detail services are not available",
+                    "missing_services": missing_services,
+                    "required_services": required_services,
+                    "available_services": [s for s in available_services if "action" in s],
+                    "suggestions": [
+                        "Use get_actions() to list available actions",
+                        "Use get_action_type() to get action type from action name",
+                        "Action details may not be exposed by this rosbridge/rosapi version",
+                        "Consider subscribing to action topics directly for live message inspection",
+                    ],
+                    "note": "Action detail services (/rosapi/action_*_details) are not part of standard rosapi",
+                },
+            }
+
     result = {"action_type": action_type, "goal": {}, "result": {}, "feedback": {}}
 
     # Get goal, result, and feedback details in a single WebSocket context
@@ -2475,6 +2615,50 @@ def inspect_all_actions() -> dict:
         dict: Contains detailed information about all actions,
             including action names, types, and server information.
     """
+    # Check if required action services are available
+    required_services = ["/rosapi/action_servers"]
+
+    with ws_manager:
+        # Get available services to check compatibility
+        services_message = {
+            "op": "call_service",
+            "service": "/rosapi/services",
+            "type": "rosapi/Services",
+            "args": {},
+            "id": "check_services_for_inspect_actions",
+        }
+
+        services_response = ws_manager.request(services_message)
+        if not services_response or not isinstance(services_response, dict):
+            return {
+                "error": "Failed to check service availability",
+                "compatibility": {
+                    "issue": "Cannot determine available services",
+                    "required_services": required_services,
+                    "suggestion": "Ensure rosbridge is running and rosapi is available",
+                },
+            }
+
+        available_services = services_response.get("values", {}).get("services", [])
+        missing_services = [svc for svc in required_services if svc not in available_services]
+
+        if missing_services:
+            return {
+                "error": "Action inspection not supported by this rosbridge/rosapi version",
+                "compatibility": {
+                    "issue": "Required action services are not available",
+                    "missing_services": missing_services,
+                    "required_services": required_services,
+                    "available_services": [s for s in available_services if "action" in s],
+                    "suggestions": [
+                        "This rosbridge version doesn't support action inspection services",
+                        "Use get_actions() to list available actions",
+                        "Consider upgrading rosbridge or using a different implementation",
+                    ],
+                    "note": "Action inspection requires /rosapi/action_servers service",
+                },
+            }
+
     # First get all actions
     actions_message = {
         "op": "call_service",