Refactor default path handling to use task-type configuration

Co-authored-by: momchil-flex <92756559+momchil-flex@users.noreply.github.com>

Author: Copilot

tidy3d/web/api/webapi.py

@@ -68,6 +68,61 @@
     "VOLUME_MESH": "VolumeMesher",
 }
 
+# map task_type to default data filename
+DEFAULT_DATA_FILENAME = {
+    "FDTD": "simulation_data.hdf5",
+    "MODE_SOLVER": "simulation_data.hdf5",
+    "MODE": "simulation_data.hdf5",
+    "EME": "simulation_data.hdf5",
+    "HEAT": "simulation_data.hdf5",
+    "HEAT_CHARGE": "simulation_data.hdf5",
+    "VOLUME_MESH": "simulation_data.hdf5",
+    "COMPONENT_MODELER": "cm_data.hdf5",
+    "TERMINAL_COMPONENT_MODELER": "cm_data.hdf5",
+    "RF": "cm_data.hdf5",
+}
+
+
+def _get_default_path(task_id: str, provided_path: PathLike) -> Path:
+    """Get the appropriate default path based on task type.
+
+    If the user provided a non-default path, returns it as-is.
+    Otherwise, returns the task-type-specific default filename.
+
+    Parameters
+    ----------
+    task_id : str
+        Unique identifier of task on server.
+    provided_path : PathLike
+        Path provided by the user.
+
+    Returns
+    -------
+    Path
+        The appropriate path to use for this task type.
+    """
+    path = Path(provided_path)
+
+    # If user provided a custom path (not the generic default), respect it
+    if path.name not in {"simulation_data.hdf5", "simulation_data.hdf5.gz"}:
+        return path
+
+    # Determine task type
+    if _is_modeler_batch(task_id):
+        task_type = "RF"
+    else:
+        task_info = get_info(task_id)
+        task_type = task_info.taskType
+
+    # Get the task-type-specific default filename
+    default_filename = DEFAULT_DATA_FILENAME.get(task_type, "simulation_data.hdf5")
+
+    # Preserve .gz extension if present
+    if path.name.endswith(".gz") and not default_filename.endswith(".gz"):
+        default_filename += ".gz"
+
+    return path.with_name(default_filename)
+
 
 def _get_url(task_id: str) -> str:
     """Get the URL for a task on our server."""
@@ -1018,15 +1073,10 @@ def download(
         Optional callback function called when downloading file with ``bytes_in_chunk`` as argument.
 
     """
-    path = Path(path)
+    # Get the appropriate default path based on task type
+    path = _get_default_path(task_id, path)
 
     if _is_modeler_batch(task_id):
-        # Use a more descriptive default filename for component modeler downloads.
-        # If the caller left the default as 'simulation_data.hdf5', prefer 'cm_data.hdf5'.
-        # TODO: seems like the default should then be maybe set to None and defined somewhere else
-        # per task type?
-        if path.name == "simulation_data.hdf5":
-            path = path.with_name("cm_data.hdf5")
         BatchTask(task_id).get_data_hdf5(
             remote_data_file_gz=CM_DATA_HDF5_GZ,
             to_file=path,
@@ -1182,14 +1232,11 @@ def load(
     Union[:class:`.SimulationData`, :class:`.HeatSimulationData`, :class:`.EMESimulationData`]
         Object containing simulation data.
     """
-    path = Path(path)
-    # For component modeler batches, default to a clearer filename if the default was used.
-    if (
-        task_id
-        and _is_modeler_batch(task_id)
-        and path.name in {"simulation_data.hdf5", "simulation_data.hdf5.gz"}
-    ):
-        path = path.with_name(path.name.replace("simulation", "cm"))
+    # Get the appropriate default path based on task type
+    if task_id is not None:
+        path = _get_default_path(task_id, path)
+    else:
+        path = Path(path)
 
     if task_id is None:
         if not path.exists():