diff --git a/ament_cmake_auto/cmake/ament_auto_generate_code.cmake b/ament_cmake_auto/cmake/ament_auto_generate_code.cmake
index 67a44ab8..a5d7c954 100644
--- a/ament_cmake_auto/cmake/ament_auto_generate_code.cmake
+++ b/ament_cmake_auto/cmake/ament_auto_generate_code.cmake
@@ -13,10 +13,90 @@
 # limitations under the License.
 
 #
-# Execute the extension point ``ament_auto_generate_code``.
+# Generate code from msg/srv/action interface files.
+#
+# Requires that the package declares all of the following in `package.xml`:
+# - runtime dependency on `rosidl_default_runtime`
+# - buildtool dependency on `rosidl_default_generators`
+# - membership in group `rosidl_interface_packages`
+# If any is missing, the macro fails with a hint message.
+#
+# :param TARGETS: list of targets in same package that should be linked against
+#   same package's interface typesupport library so they can use the generated code of interfaces.
+# :type TARGETS: list of strings
 #
 # @public
 #
 macro(ament_auto_generate_code)
+  cmake_parse_arguments(_ARG "" "" "TARGETS" ${ARGN})
+  if(_ARG_UNPARSED_ARGUMENTS)
+    message(FATAL_ERROR "ament_auto_generate_code called with unused arguments: ${_ARG_UNPARSED_ARGUMENTS}")
+  endif()
+
+  # Ensure package.xml is parsed so *_DEPENDS variables are available
+  if(NOT _AMENT_PACKAGE_NAME)
+    ament_package_xml()
+  endif()
+
+  # Validate required <exec_depend> tags
+  if(NOT rosidl_default_runtime IN_LIST ${PROJECT_NAME}_EXEC_DEPENDS)
+    message(FATAL_ERROR
+      "ament_auto_generate_code: '${PROJECT_NAME}' must declare an exec_depend on 'rosidl_default_runtime' to use generated interfaces at runtime.\n"
+      "Hint:\n"
+      "  - package.xml: add <exec_depend>rosidl_default_runtime</exec_depend>\n")
+  endif()
+
+  # Validate required <buildtool_depend> tags
+  if(NOT rosidl_default_generators IN_LIST ${PROJECT_NAME}_BUILDTOOL_DEPENDS)
+    message(FATAL_ERROR
+      "ament_auto_generate_code: '${PROJECT_NAME}' must declare a buildtool dependency on 'rosidl_default_generators' to generate interfaces.\n"
+      "Hint:\n"
+      "  - package.xml: add <buildtool_depend>rosidl_default_generators</buildtool_depend>\n")
+  endif()
+
+  # Validate required <member_of_group> tags
+  if(NOT rosidl_interface_packages IN_LIST ${PROJECT_NAME}_MEMBER_OF_GROUPS)
+    message(FATAL_ERROR
+      "ament_auto_generate_code: '${PROJECT_NAME}' should join a `rosidl_interface_packages` group so tools can discover interface packages.\n"
+      "Hint:\n"
+      "  - package.xml: add <member_of_group>rosidl_interface_packages</member_of_group>\n")
+  endif()
+
+  set(${PROJECT_NAME}_interface_files "")
+  file(
+    GLOB
+    ${PROJECT_NAME}_interface_files
+    RELATIVE
+    "${CMAKE_CURRENT_SOURCE_DIR}"
+    CONFIGURE_DEPENDS
+    "msg/*.msg"
+    "srv/*.srv"
+    "action/*.action"
+  )
+
+  if(NOT ${PROJECT_NAME}_interface_files)
+    message(WARNING "ament_auto_generate_code: no message, service, or action files found")
+    return()
+  endif()
+
+  # Only forward DEPENDENCIES if present to avoid passing empty args
+  set(_rosidl_args
+    ${PROJECT_NAME}
+    ${${PROJECT_NAME}_interface_files}
+  )
+  if(${PROJECT_NAME}_FOUND_BUILD_DEPENDS)
+    list(APPEND _rosidl_args DEPENDENCIES ${${PROJECT_NAME}_FOUND_BUILD_DEPENDS})
+  endif()
+  rosidl_generate_interfaces(${_rosidl_args})
+  ament_export_dependencies(rosidl_default_runtime)
+
+  # Optionally wire interfaces into same-package targets
+  if(_ARG_TARGETS)
+    rosidl_get_typesupport_target(${PROJECT_NAME}_auto_typesupport_target ${PROJECT_NAME} rosidl_typesupport_cpp)
+    foreach(target IN LISTS _ARG_TARGETS)
+      target_link_libraries(${target} ${${PROJECT_NAME}_auto_typesupport_target})
+    endforeach()
+  endif()
+
   ament_execute_extensions(ament_auto_generate_code)
 endmacro()