diff --git a/src/gz21_ocean_momentum/cli/data.py b/src/gz21_ocean_momentum/cli/data.py
index 6187a298..db082bc2 100755
--- a/src/gz21_ocean_momentum/cli/data.py
+++ b/src/gz21_ocean_momentum/cli/data.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
-import gz21_ocean_momentum.step.data.lib as lib
+import gz21_ocean_momentum.lib.data as lib
 import gz21_ocean_momentum.common.cli as cli
 from   gz21_ocean_momentum.common.bounding_box import BoundingBox
 import gz21_ocean_momentum.common.bounding_box as bounding_box
@@ -60,14 +60,15 @@
 logger.debug("dropping irrelevant data variables...")
 surface_fields = surface_fields[["usurf", "vsurf"]]
 
-if options.ntimes is not None:
-    logger.info(f"slicing {options.ntimes} time points...")
-    surface_fields = surface_fields.isel(time=slice(options.ntimes))
-
 logger.info("selecting input data bounding box...")
 surface_fields = bounding_box.bound_dataset("yu_ocean", "xu_ocean", surface_fields, bbox)
 grid = bounding_box.bound_dataset("yu_ocean", "xu_ocean", grid, bbox)
 
+# TODO 2023-11-29 raehik: original bounded first, sliced (immediately) after
+if options.ntimes is not None:
+    logger.info(f"slicing {options.ntimes} time points...")
+    surface_fields = surface_fields.isel(time=slice(options.ntimes))
+
 logger.debug("placing grid dataset into local memory...")
 grid = grid.compute()
 
diff --git a/src/gz21_ocean_momentum/cli/infer.py b/src/gz21_ocean_momentum/cli/infer.py
index 1e32cda7..696b7cd2 100755
--- a/src/gz21_ocean_momentum/cli/infer.py
+++ b/src/gz21_ocean_momentum/cli/infer.py
@@ -1,9 +1,11 @@
 import configargparse
 
+import gz21_ocean_momentum.common.cli as cli
 import logging
 from dask.diagnostics import ProgressBar
 from gz21_ocean_momentum.utils import TaskInfo
 
+import gz21_ocean_momentum.lib.model as lib
 from gz21_ocean_momentum.data.datasets import (
     pytorch_dataset_from_cm2_6_forcing_dataset,
     #DatasetPartitioner,
@@ -13,27 +15,18 @@
 )
 
 import xarray as xr
-
 import torch
 from torch.utils.data import DataLoader
 
-# TODO hardcode submodel, transformation, NN loss function
-# unlikely for a CLI we need to provide dynamic code loading -- let's just give
-# options
-# we could enable such "dynamic loading" in the "library" interface!-- but, due
-# to the class-based setup, it's a little complicated for a user to come in with
-# their own code for some of these, and it needs documentation. so a task for
-# later
 import gz21_ocean_momentum.models.models1 as model
 import gz21_ocean_momentum.models.submodels as submodels
 import gz21_ocean_momentum.models.transforms as transforms
 import gz21_ocean_momentum.train.losses as loss_funcs
 from gz21_ocean_momentum.inference.utils import predict_lazy_cm2_6
-#from gz21_ocean_momentum.train.base import Trainer
 
 submodel = submodels.transform3
 
-DESCRIPTION = """
+_cli_desc = """
 Use a trained GZ21 neural net to predict forcing for input ocean velocity data.
 
 This script is intended as example of how use the GZ21 neural net, generating
@@ -54,21 +47,21 @@
 into your GCM of choice.
 """
 
-p = configargparse.ArgParser(description=DESCRIPTION)
+p = configargparse.ArgParser(description=_cli_desc)
 p.add("--config-file", is_config_file=True, help="config file path")
-
 p.add("--input-data-dir", type=str, required=True, help="path to input ocean velocity data, in zarr format (folder)")
 p.add("--model-state-dict-file", type=str, required=True, help="model state dict file (*.pth)")
 p.add("--out-dir", type=str, required=True,  help="folder to save forcing predictions dataset to (in zarr format)")
-
 p.add("--device",  type=str, default="cuda", help="neural net device (e.g. cuda, cuda:0, cpu)")
-p.add("--splits",  type=int)
 
 options = p.parse_args()
 
 logging.basicConfig(level=logging.INFO)
 logger = logging.getLogger(__name__)
 
+cli.fail_if_path_is_nonempty_dir(
+        1, f"--out-dir \"{options.out_dir}\" invalid", options.out_dir)
+
 # ---
 
 logger.info("loading input (coarse) ocean momentum data...")
@@ -77,14 +70,7 @@
 with ProgressBar(), TaskInfo("Applying transforms to dataset"):
     ds_computed_xr = submodel.fit_transform(ds_computed_xr)
 
-ds_computed_torch = pytorch_dataset_from_cm2_6_forcing_dataset(ds_computed_xr)
-
-logger.info("performing various dataset transforms...")
-features_transform_ = ComposeTransforms()
-targets_transform_ = ComposeTransforms()
-transform = DatasetTransformer(features_transform_, targets_transform_)
-dataset = DatasetWithTransform(ds_computed_torch, transform)
-
+dataset = lib.gz21_train_data_subdomain_xr_to_torch(ds_computed_xr)
 loader = DataLoader(dataset)
 
 criterion = loss_funcs.HeteroskedasticGaussianLossV2(dataset.n_targets)
diff --git a/src/gz21_ocean_momentum/cli/train.py b/src/gz21_ocean_momentum/cli/train.py
index 93de42ac..b7c15bd1 100755
--- a/src/gz21_ocean_momentum/cli/train.py
+++ b/src/gz21_ocean_momentum/cli/train.py
@@ -7,7 +7,7 @@
 import gz21_ocean_momentum.common.cli as cli
 import gz21_ocean_momentum.common.assorted as common
 import gz21_ocean_momentum.common.bounding_box as bounding_box
-import gz21_ocean_momentum.unsorted.train_data_xr_to_pytorch as lib
+import gz21_ocean_momentum.lib.model as lib
 import gz21_ocean_momentum.models.submodels as submodels
 import gz21_ocean_momentum.models.transforms as transforms
 import gz21_ocean_momentum.models.models1 as model
diff --git a/src/gz21_ocean_momentum/data/datasets.py b/src/gz21_ocean_momentum/data/datasets.py
index 0c7ab637..815c0cbf 100644
--- a/src/gz21_ocean_momentum/data/datasets.py
+++ b/src/gz21_ocean_momentum/data/datasets.py
@@ -429,7 +429,6 @@ def transform(self, x):
         return np.concatenate((left, x, right), axis=self.axis)
 
     def transform_coordinate(self, coords, dim):
-        print(f"{dim}, {self.dim_name}")
         if dim == self.dim_name:
             left = coords[-self.nb_points :] - self.length
             right = coords[: self.nb_points] + self.length
@@ -697,8 +696,6 @@ def __len__(self):
             Number of samples of the dataset.
 
         """
-        print("xrrawdataset len called")
-        print(len(self.xr_dataset[self._index]))
         try:
             return len(self.xr_dataset[self._index])
         except KeyError as e:
@@ -797,7 +794,6 @@ def __getattr__(self, attr):
         raise AttributeError()
 
     def __len__(self):
-        print("len on datasetwithtransform")
         return len(self.dataset)
 
     def add_transforms_from_model(self, model):
@@ -914,6 +910,8 @@ class ConcatDataset_(ConcatDataset):
     - enforces the concatenated dataset to have the same shapes
     - passes on attributes (from the first dataset, assuming they are
                             equal accross concatenated datasets)
+
+    TODO input datasets need to have .height, .width
     """
 
     def __init__(self, datasets):
diff --git a/src/gz21_ocean_momentum/step/data/lib.py b/src/gz21_ocean_momentum/lib/data.py
similarity index 100%
rename from src/gz21_ocean_momentum/step/data/lib.py
rename to src/gz21_ocean_momentum/lib/data.py
diff --git a/src/gz21_ocean_momentum/unsorted/train_data_xr_to_pytorch.py b/src/gz21_ocean_momentum/lib/model.py
similarity index 83%
rename from src/gz21_ocean_momentum/unsorted/train_data_xr_to_pytorch.py
rename to src/gz21_ocean_momentum/lib/model.py
index 22f82bd6..1af01e32 100644
--- a/src/gz21_ocean_momentum/unsorted/train_data_xr_to_pytorch.py
+++ b/src/gz21_ocean_momentum/lib/model.py
@@ -1,7 +1,11 @@
+# Common functions relating to neural net model, training data.
+
 import xarray as xr
 import numpy as np
 import torch.utils.data as torch
 
+from gz21_ocean_momentum.common.assorted import at_idx_pct
+
 from gz21_ocean_momentum.data.datasets import (
     DatasetWithTransform,
     DatasetTransformer,
@@ -11,7 +15,11 @@
     ComposeTransforms,
 )
 
-def cm26_xarray_to_torch(ds_xr: xr.Dataset):
+def cm26_xarray_to_torch(ds_xr: xr.Dataset) -> torch.Dataset:
+    """
+    Obtain a PyTorch `Dataset` view over an xarray dataset, specifically for
+    CM2.6 ocean velocity data annotated with forcings in `S_x` and `S_y`.
+    """
     ds_torch = RawDataFromXrDataset(ds_xr)
     ds_torch.index = "time"
     ds_torch.add_input("usurf")
@@ -20,7 +28,7 @@ def cm26_xarray_to_torch(ds_xr: xr.Dataset):
     ds_torch.add_output("S_y")
     return ds_torch
 
-def gz21_train_data_subdomain_xr_to_torch(ds_xr: xr.Dataset):
+def gz21_train_data_subdomain_xr_to_torch(ds_xr: xr.Dataset) -> torch.Dataset:
     """
     Convert GZ21 training data (coarsened CM2.6 data with diagnosed forcings)
     into a PyTorch dataset.
@@ -39,22 +47,6 @@ def gz21_train_data_subdomain_xr_to_torch(ds_xr: xr.Dataset):
 
     return ds_torch_with_transform
 
-def at_idx_pct(pct: float, a) -> int:
-    """
-    Obtain the index into the given list-like to the given percent.
-    No interpolation is performed: we choose the leftmost closest index i.e. the
-    result is floored.
-
-    e.g. `at_idx_pct(0.5, [0,1,2]) == 1`
-
-    Must be able to `len(a)`.
-
-    Invariant: `0<=pct<=1`.
-
-    Returns a valid index into `a`.
-    """
-    return int(pct * len(a))
-
 def prep_train_test_dataloaders(
         dss: list,
         pct_train_end:  float,
diff --git a/src/gz21_ocean_momentum/step/inference/lib.py b/src/gz21_ocean_momentum/step/inference/lib.py
deleted file mode 100644
index 15684272..00000000
--- a/src/gz21_ocean_momentum/step/inference/lib.py
+++ /dev/null
@@ -1,9 +0,0 @@
-def cm2_6_prep_pytorch(_: xr.Dataset, idx_start: float, idx_end) -> _:
-    """
-    Various transformations, subsetting of a CM2.6 dataset.
-
-    Retrieve using data step lib, slice & restrict spatial domain.
-
-    idx_start: 0->1 subset of dataset to use, start
-    idx_end:   0->1 subset of dataset to use, end (must be > idx_start)
-    """