modes: make available modes user selectable with a registration option

Some modes should only be run within the context of a mode executor and the user should not be able
to select them in the GCS. With this change, the external component registration request can be
used to set if a mode is selectable or not.

msg/px4_msgs_old/msg/RegisterExtComponentReplyV0.msg

@@ -0,0 +1,15 @@
+uint32 MESSAGE_VERSION = 0
+
+uint64 timestamp # time since system start (microseconds)
+
+uint64 request_id          # ID from the request
+char[25] name              # name from the request
+
+uint16 px4_ros2_api_version
+
+bool success
+int8 arming_check_id      # arming check registration ID (-1 if invalid)
+int8 mode_id              # assigned mode ID (-1 if invalid)
+int8 mode_executor_id     # assigned mode executor ID (-1 if invalid)
+
+uint8 ORB_QUEUE_LENGTH = 2

msg/px4_msgs_old/msg/RegisterExtComponentRequestV0.msg

@@ -0,0 +1,24 @@
+# Request to register an external component
+
+uint32 MESSAGE_VERSION = 0
+
+uint64 timestamp # time since system start (microseconds)
+
+uint64 request_id                  # ID, set this to a random value
+char[25] name                      # either the requested mode name, or component name
+
+uint16 LATEST_PX4_ROS2_API_VERSION = 1 # API version compatibility. Increase this on a breaking semantic change. Changes to any message field are detected separately and do not require an API version change.
+
+uint16 px4_ros2_api_version   # Set to LATEST_PX4_ROS2_API_VERSION
+
+# Components to be registered
+bool register_arming_check
+bool register_mode                 # registering a mode also requires arming_check to be set
+bool register_mode_executor        # registering an executor also requires a mode to be registered (which is the owned mode by the executor)
+
+bool enable_replace_internal_mode  # set to true if an internal mode should be replaced
+uint8 replace_internal_mode        # vehicle_status::NAVIGATION_STATE_*
+bool activate_mode_immediately     # switch to the registered mode (can only be set in combination with an executor)
+
+
+uint8 ORB_QUEUE_LENGTH = 2

msg/translation_node/translations/all_translations.h

@@ -12,6 +12,8 @@
 #include "translation_battery_status_v1.h"
 #include "translation_event_v1.h"
 #include "translation_home_position_v1.h"
+#include "translation_register_ext_component_reply_v1.h"
+#include "translation_register_ext_component_request_v1.h"
 #include "translation_vehicle_attitude_setpoint_v1.h"
 #include "translation_vehicle_status_v1.h"
 #include "translation_vehicle_local_position_v1.h"

msg/translation_node/translations/translation_register_ext_component_reply_v1.h

@@ -0,0 +1,45 @@
+/****************************************************************************
+ * Copyright (c) 2025 PX4 Development Team.
+ * SPDX-License-Identifier: BSD-3-Clause
+ ****************************************************************************/
+#pragma once
+
+// Translate RegisterExtComponentReply v0 <--> v1
+#include <px4_msgs_old/msg/register_ext_component_reply_v0.hpp>
+#include <px4_msgs/msg/register_ext_component_reply.hpp>
+
+class RegisterExtComponentReplyV1Translation {
+public:
+    using MessageOlder = px4_msgs_old::msg::RegisterExtComponentReplyV0;
+    static_assert(MessageOlder::MESSAGE_VERSION == 0);
+
+    using MessageNewer = px4_msgs::msg::RegisterExtComponentReply;
+    static_assert(MessageNewer::MESSAGE_VERSION == 1);
+
+    static constexpr const char* kTopic = "fmu/out/register_ext_component_reply";
+
+    static void fromOlder(const MessageOlder &msg_older, MessageNewer &msg_newer) {
+	    msg_newer.timestamp = msg_older.timestamp;
+	    msg_newer.request_id = msg_older.request_id;
+	    msg_newer.name = msg_older.name;
+	    msg_newer.px4_ros2_api_version = msg_older.px4_ros2_api_version;
+	    msg_newer.success = msg_older.success;
+	    msg_newer.arming_check_id = msg_older.arming_check_id;
+	    msg_newer.mode_id = msg_older.mode_id;
+	    msg_newer.mode_executor_id = msg_older.mode_executor_id;
+	    msg_newer.not_user_selectable = false;
+    }
+
+    static void toOlder(const MessageNewer &msg_newer, MessageOlder &msg_older) {
+	    msg_older.timestamp = msg_newer.timestamp;
+	    msg_older.request_id = msg_newer.request_id;
+	    msg_older.name = msg_newer.name;
+	    msg_older.px4_ros2_api_version = msg_newer.px4_ros2_api_version;
+	    msg_older.success = msg_newer.success;
+	    msg_older.arming_check_id = msg_newer.arming_check_id;
+	    msg_older.mode_id = msg_newer.mode_id;
+	    msg_older.mode_executor_id = msg_newer.mode_executor_id;
+    }
+};
+
+REGISTER_TOPIC_TRANSLATION_DIRECT(RegisterExtComponentReplyV1Translation);

msg/translation_node/translations/translation_register_ext_component_request_v1.h

@@ -0,0 +1,49 @@
+/****************************************************************************
+ * Copyright (c) 2025 PX4 Development Team.
+ * SPDX-License-Identifier: BSD-3-Clause
+ ****************************************************************************/
+#pragma once
+
+// Translate RegisterExtComponentRequest v0 <--> v1
+#include <px4_msgs_old/msg/register_ext_component_request_v0.hpp>
+#include <px4_msgs/msg/register_ext_component_request.hpp>
+
+class RegisterExtComponentRequestV1Translation {
+public:
+    using MessageOlder = px4_msgs_old::msg::RegisterExtComponentRequestV0;
+    static_assert(MessageOlder::MESSAGE_VERSION == 0);
+
+    using MessageNewer = px4_msgs::msg::RegisterExtComponentRequest;
+    static_assert(MessageNewer::MESSAGE_VERSION == 1);
+
+    static constexpr const char* kTopic = "fmu/in/register_ext_component_request";
+
+    static void fromOlder(const MessageOlder &msg_older, MessageNewer &msg_newer) {
+	    msg_newer.timestamp = msg_older.timestamp;
+	    msg_newer.request_id = msg_older.request_id;
+	    msg_newer.name = msg_older.name;
+	    msg_newer.px4_ros2_api_version = msg_older.px4_ros2_api_version;
+	    msg_newer.register_arming_check = msg_older.register_arming_check;
+	    msg_newer.register_mode = msg_older.register_mode;
+	    msg_newer.register_mode_executor = msg_older.register_mode_executor;
+	    msg_newer.enable_replace_internal_mode = msg_older.enable_replace_internal_mode;
+	    msg_newer.replace_internal_mode = msg_older.replace_internal_mode;
+	    msg_newer.activate_mode_immediately = msg_older.activate_mode_immediately;
+	    msg_newer.not_user_selectable = false;
+    }
+
+    static void toOlder(const MessageNewer &msg_newer, MessageOlder &msg_older) {
+	    msg_older.timestamp = msg_newer.timestamp;
+	    msg_older.request_id = msg_newer.request_id;
+	    msg_older.name = msg_newer.name;
+	    msg_older.px4_ros2_api_version = msg_newer.px4_ros2_api_version;
+	    msg_older.register_arming_check = msg_newer.register_arming_check;
+	    msg_older.register_mode = msg_newer.register_mode;
+	    msg_older.register_mode_executor = msg_newer.register_mode_executor;
+	    msg_older.enable_replace_internal_mode = msg_newer.enable_replace_internal_mode;
+	    msg_older.replace_internal_mode = msg_newer.replace_internal_mode;
+	    msg_older.activate_mode_immediately = msg_newer.activate_mode_immediately;
+    }
+};
+
+REGISTER_TOPIC_TRANSLATION_DIRECT(RegisterExtComponentRequestV1Translation);

msg/versioned/RegisterExtComponentReply.msg

@@ -1,4 +1,4 @@
-uint32 MESSAGE_VERSION = 0
+uint32 MESSAGE_VERSION = 1
 
 uint64 timestamp # time since system start (microseconds)
 
@@ -12,4 +12,6 @@ int8 arming_check_id      # arming check registration ID (-1 if invalid)
 int8 mode_id              # assigned mode ID (-1 if invalid)
 int8 mode_executor_id     # assigned mode executor ID (-1 if invalid)
 
+bool not_user_selectable  # mode cannot be selected by the user
+
 uint8 ORB_QUEUE_LENGTH = 2

msg/versioned/RegisterExtComponentRequest.msg

@@ -1,6 +1,6 @@
 # Request to register an external component
 
-uint32 MESSAGE_VERSION = 0
+uint32 MESSAGE_VERSION = 1
 
 uint64 timestamp # time since system start (microseconds)
 
@@ -19,6 +19,6 @@ bool register_mode_executor        # registering an executor also requires a mod
 bool enable_replace_internal_mode  # set to true if an internal mode should be replaced
 uint8 replace_internal_mode        # vehicle_status::NAVIGATION_STATE_*
 bool activate_mode_immediately     # switch to the registered mode (can only be set in combination with an executor)
-
+bool not_user_selectable           # mode cannot be selected by the user
 
 uint8 ORB_QUEUE_LENGTH = 2

src/modules/commander/ModeManagement.cpp

@@ -232,6 +232,7 @@ void ModeManagement::checkNewRegistrations(UpdateRequest &update_request)
 		static_assert(sizeof(request.name) == sizeof(reply.name), "size mismatch");
 		memcpy(reply.name, request.name, sizeof(request.name));
 		reply.request_id = request.request_id;
+		reply.not_user_selectable = request.not_user_selectable;
 		reply.px4_ros2_api_version = register_ext_component_request_s::LATEST_PX4_ROS2_API_VERSION;
 
 		// validate

src/modules/mavlink/streams/AVAILABLE_MODES.hpp

@@ -38,6 +38,7 @@
 #include <uORB/topics/register_ext_component_reply.h>
 #include <lib/modes/standard_modes.hpp>
 #include <lib/modes/ui.hpp>
+#include <limits.h>
 
 class MavlinkStreamAvailableModes : public MavlinkStream
 {
@@ -71,6 +72,8 @@ private:
 		char name[sizeof(register_ext_component_reply_s::name)] {};
 	};
 	ExternalModeName *_external_mode_names{nullptr};
+	uint8_t _not_user_selectable_mask{0};
+	static_assert(MAX_NUM_EXTERNAL_MODES <= (sizeof(_not_user_selectable_mask) * CHAR_BIT), "Mask too small");
 
 	uORB::Subscription _vehicle_status_sub{ORB_ID(vehicle_status)};
 	uORB::Subscription _register_ext_component_reply_sub{ORB_ID(register_ext_component_reply)};
@@ -116,6 +119,10 @@ private:
 				} else if (_external_mode_names) {
 					strncpy(available_modes.mode_name, _external_mode_names[external_mode_index].name, sizeof(available_modes.mode_name));
 					available_modes.mode_name[sizeof(available_modes.mode_name) - 1] = '\0';
+
+					if ((_not_user_selectable_mask & (1 << external_mode_index)) > 0) {
+						available_modes.properties |= MAV_MODE_PROPERTY_NOT_USER_SELECTABLE;
+					}
 				}
 
 			} else { // Internal
@@ -205,6 +212,13 @@ private:
 
 				if (_external_mode_names && mode_index < MAX_NUM_EXTERNAL_MODES) {
 					memcpy(_external_mode_names[mode_index].name, reply.name, sizeof(ExternalModeName::name));
+
+					if (reply.not_user_selectable) {
+						_not_user_selectable_mask |= (1 << mode_index);
+
+					} else {
+						_not_user_selectable_mask &= ~(1 << mode_index);
+					}
 				}
 
 				dynamic_update = true;