fix: mission launch file now correctly loads env-specific config at launch time

src/rov_mission/launch/mission.launch.py

@@ -1,30 +1,52 @@
-"""Mission executor launch file."""
+"""
+Mission executor launch file.
+Selects config based on env argument at launch time.
 
+Usage:
+  ros2 launch rov_mission mission.launch.py          # dev config (default)
+  ros2 launch rov_mission mission.launch.py env:=field  # field config
+"""
 from launch import LaunchDescription
-from launch.actions import DeclareLaunchArgument
+from launch.actions import DeclareLaunchArgument, OpaqueFunction
 from launch.substitutions import LaunchConfiguration
 from launch_ros.actions import Node
 from ament_index_python.packages import get_package_share_directory
 import os
 
 
-def generate_launch_description():
+def _launch_with_config(context, *args, **kwargs):
+    """Resolve env argument and return node with correct config file."""
     pkg_dir = get_package_share_directory('rov_mission')
 
-    env_arg = DeclareLaunchArgument(
-        'env', default_value='dev',
-        description='Deployment environment: dev, field'
-    )
+    # Evaluate env argument at launch time
+    env = LaunchConfiguration('env').perform(context)
 
-    env = LaunchConfiguration('env')
+    config_file = os.path.join(pkg_dir, 'config', f'{env}.yaml')
 
-    return LaunchDescription([
-        env_arg,
+    if not os.path.exists(config_file):
+        raise FileNotFoundError(
+            f'Config file not found: {config_file}. '
+            f'Valid environments: dev, field'
+        )
+
+    return [
         Node(
             package='rov_mission',
             executable='mission_executor',
             name='mission_executor',
             output='screen',
-            # Config selected by env argument at launch time
+            parameters=[config_file],
+        )
+    ]
+
+
+def generate_launch_description():
+    """Launch mission executor with environment-specific config."""
+    return LaunchDescription([
+        DeclareLaunchArgument(
+            'env',
+            default_value='dev',
+            description='Deployment environment: dev, field'
         ),
+        OpaqueFunction(function=_launch_with_config),
     ])