diff --git a/scdataloader/collator.py b/scdataloader/collator.py
index b9d7c41..4342545 100644
--- a/scdataloader/collator.py
+++ b/scdataloader/collator.py
@@ -8,6 +8,20 @@
 from .utils import load_genes
 
 
+def build_axis_mapping(native_axis: list[str], global_gene_index: dict[str, int]):
+    """Map one artifact's native gene axis into the model's global gene axis."""
+    positions = np.fromiter(
+        (global_gene_index.get(gene, -1) for gene in native_axis),
+        dtype=np.int64,
+        count=len(native_axis),
+    )
+    accepted = positions >= 0
+    model_positions = positions[accepted]
+    if len(model_positions) == 0:
+        raise ValueError("native var axis has no model genes")
+    return accepted, model_positions
+
+
 class Collator:
     def __init__(
         self,
@@ -25,6 +39,7 @@ def __init__(
         class_names: List[str] = [],
         genelist: List[str] = [],
         genedf: Optional[pd.DataFrame] = None,
+        storage_gene_mappings: list[tuple[np.ndarray, np.ndarray]] | None = None,
     ):
         """
         Collator for preparing gene expression data batches for the scPRINT model.
@@ -94,6 +109,7 @@ def __init__(
         self.organism_name = organism_name
         self.tp_name = tp_name
         self.class_names = class_names
+        self.storage_gene_mappings = storage_gene_mappings
         self.start_idx = {}
         self.accepted_genes = {}
         self.to_subset = {}
@@ -156,7 +172,7 @@ def __call__(self, batch) -> dict[str, Tensor]:
                 - organism_name (any): Organism identifier (column name set by `organism_name`).
                 - tp_name (float, optional): Time point value (column name set by `tp_name`).
                 - class_names... (any, optional): Additional class labels.
-                - "_storage_idx" (int, optional): Dataset storage index.
+                - "_store_idx" (int, optional): Dataset storage index.
                 - "is_meta" (int, optional): Metadata flag.
                 - "knn_cells" (array, optional): KNN neighbor expression data.
                 - "knn_cells_info" (array, optional): KNN neighbor metadata.
@@ -178,7 +194,7 @@ def __call__(self, batch) -> dict[str, Tensor]:
                 - "knn_cells_info" (Tensor, optional): KNN metadata. Present if input
                   contains "knn_cells_info".
                 - "dataset" (Tensor, optional): Dataset indices as int64. Present if input
-                  contains "_storage_idx".
+                  contains "_store_idx".
 
         Note:
             Batch size in output may be smaller than input if some samples are filtered
@@ -198,14 +214,30 @@ def __call__(self, batch) -> dict[str, Tensor]:
         knn_cells = []
         knn_cells_info = []
         for elem in batch:
+            storage_mapping = None
+            storage_gene_locs = None
             organism_id = elem[self.organism_name]
             if organism_id not in self.organism_ids:
                 continue
-            if "_storage_idx" in elem:
-                dataset.append(elem["_storage_idx"])
+            storage_idx = elem.get("_store_idx", elem.get("_storage_idx"))
+            if storage_idx is not None:
+                dataset.append(storage_idx)
             expr = np.array(elem["X"])
             total_count.append(expr.sum())
-            if len(self.accepted_genes) > 0:
+            if self.storage_gene_mappings is not None:
+                if storage_idx is None:
+                    raise KeyError("storage-aware gene mapping requires _store_idx")
+                storage_mapping = self.storage_gene_mappings[int(storage_idx)]
+                accepted, storage_gene_locs = storage_mapping
+                if len(expr) != len(accepted):
+                    raise ValueError(
+                        "expression/native-axis length mismatch for storage "
+                        f"{storage_idx}: {len(expr)} != {len(accepted)}"
+                    )
+                expr = expr[accepted]
+                if "knn_cells" in elem:
+                    elem["knn_cells"] = elem["knn_cells"][:, accepted]
+            elif len(self.accepted_genes) > 0:
                 expr = expr[self.accepted_genes[organism_id]]
                 if "knn_cells" in elem:
                     elem["knn_cells"] = elem["knn_cells"][
@@ -287,7 +319,10 @@ def __call__(self, batch) -> dict[str, Tensor]:
                 knn_cells_info.append(elem["knn_cells_info"])
             # then we need to add the start_idx to the loc to give it the correct index
             # according to the model
-            gene_locs.append(loc + self.start_idx[organism_id])
+            if storage_mapping is not None and storage_gene_locs is not None:
+                gene_locs.append(storage_gene_locs[loc])
+            else:
+                gene_locs.append(loc + self.start_idx[organism_id])
 
             if self.tp_name is not None:
                 tp.append(elem[self.tp_name])
diff --git a/scdataloader/datamodule.py b/scdataloader/datamodule.py
index 6c83377..1845dde 100644
--- a/scdataloader/datamodule.py
+++ b/scdataloader/datamodule.py
@@ -1,3 +1,4 @@
+import hashlib
 import math
 import multiprocessing as mp
 import os
@@ -12,6 +13,7 @@
 import numpy as np
 import pandas as pd
 import torch
+from lamindb.core.storage._anndata_accessor import _safer_read_index
 from torch.utils.data import DataLoader, Sampler, Subset
 from torch.utils.data.sampler import (
     RandomSampler,
@@ -21,8 +23,9 @@
 )
 from tqdm import tqdm
 
-from .collator import Collator
+from .collator import Collator, build_axis_mapping
 from .data import Dataset
+from .mapped import _Connect
 from .utils import fileToList, getBiomartTable, listToFile
 
 FILE_DIR = os.path.dirname(os.path.abspath(__file__))
@@ -38,6 +41,7 @@ def __init__(
         n_samples_per_epoch: int = 2_000_000,
         validation_split: float = 0.2,
         test_split: float = 0,
+        gene_embeddings: str = "",
         use_default_col: bool = True,
         # this is for the mappedCollection
         clss_to_predict: List[str] = ["organism_ontology_term_id"],
@@ -94,6 +98,9 @@ def __init__(
             test_split (float | int, optional): Proportion (float) or absolute number (int)
                 of samples for testing. Uses entire datasets as test sets, rounding to
                 nearest dataset boundary. Defaults to 0.
+            gene_embeddings (str, optional): Parquet file whose index defines the exact
+                model gene axis. This legacy CLI source can be paired to the model's
+                ``precpt_gene_emb`` argument. Defaults to an empty string.
             use_default_col (bool, optional): Whether to use the default Collator for batch
                 preparation. If False, no collate_fn is applied. Defaults to True.
             clss_to_predict (List[str], optional): Observation columns to encode as prediction
@@ -186,14 +193,64 @@ def __init__(
         self.metacell_mode = bool(metacell_mode)
         self.gene_pos = None
         self.collection_name = collection_name
-        if gene_subset is not None:
-            tokeep = set(mdataset.genedf.index.tolist())
-            gene_subset = [u for u in gene_subset if u in tokeep]
+        gene_frame = mdataset.genedf
+        if gene_frame is None:
+            raise ValueError("dataset gene registry is unavailable")
+        if gene_embeddings:
+            embedding_genes = (
+                pd.read_parquet(gene_embeddings, columns=[]).index.astype(str).tolist()
+            )
+            available = set(gene_frame.index.astype(str))
+            gene_subset = [gene for gene in embedding_genes if gene in available]
+        elif gene_subset is not None:
+            available = set(gene_frame.index.astype(str))
+            gene_subset = [str(gene) for gene in gene_subset if str(gene) in available]
         self.classes = {k: len(v) for k, v in mdataset.class_topred.items()}
         # we might want not to order the genes by expression (or do it?)
         # we might want to not introduce zeros and
 
         if use_default_col:
+            model_genes = gene_subset or gene_frame.index.astype(str).tolist()
+            global_gene_index = {gene: index for index, gene in enumerate(model_genes)}
+            if len(global_gene_index) != len(model_genes):
+                raise ValueError("global model gene ids are not unique")
+            mapping_cache = {}
+            storage_gene_mappings = []
+            overlap_sizes = []
+            for storage_index, storage in enumerate(
+                mdataset.mapped_dataset.storages, start=1
+            ):
+                with _Connect(storage) as store:
+                    native_axis = _safer_read_index(store["var"]).astype(str).tolist()
+                digest = hashlib.sha256("\0".join(native_axis).encode()).digest()
+                key = (len(native_axis), digest)
+                mapping = mapping_cache.get(key)
+                if mapping is None:
+                    mapping = build_axis_mapping(native_axis, global_gene_index)
+                    if len(mapping[1]) < max_len:
+                        raise ValueError(
+                            "artifact maps fewer genes than max_len: "
+                            f"storage={storage_index - 1}, mapped={len(mapping[1])}, "
+                            f"max_len={max_len}"
+                        )
+                    mapping_cache[key] = mapping
+                storage_gene_mappings.append(mapping)
+                overlap_sizes.append(len(mapping[1]))
+                if storage_index % 1000 == 0:
+                    print(
+                        "STORAGE_GENE_MAP_PROGRESS "
+                        f"{storage_index}/{len(mdataset.mapped_dataset.storages)} "
+                        f"unique_axes={len(mapping_cache)}",
+                        flush=True,
+                    )
+            print(
+                "STORAGE_GENE_MAP_PASS "
+                f"storages={len(storage_gene_mappings)} "
+                f"unique_axes={len(mapping_cache)} "
+                f"min_overlap={min(overlap_sizes)} "
+                f"max_overlap={max(overlap_sizes)}",
+                flush=True,
+            )
             kwargs["collate_fn"] = Collator(
                 organisms=mdataset.organisms if organisms is None else organisms,
                 how=how,
@@ -205,6 +262,7 @@ def __init__(
                 class_names=list(self.classes.keys()),
                 genedf=genedf,
                 n_bins=n_bins,
+                storage_gene_mappings=storage_gene_mappings,
             )
         self.gene_subset = gene_subset
         self.n_bins = n_bins
@@ -305,9 +363,21 @@ def genes(self) -> list:
 
     @property
     def genes_dict(self):
+        if self.gene_subset is None:
+            return {
+                organism: self.dataset.genedf.index[
+                    self.dataset.genedf.organism == organism
+                ].tolist()
+                for organism in self.dataset.organisms
+            }
+        organism_by_gene = self.dataset.genedf["organism"].to_dict()
         return {
-            i: self.dataset.genedf.index[self.dataset.genedf.organism == i].tolist()
-            for i in self.dataset.organisms
+            organism: [
+                gene
+                for gene in self.gene_subset
+                if organism_by_gene.get(gene) == organism
+            ]
+            for organism in self.dataset.organisms
         }
 
     def set_valid_genes_collator(self, genes):
@@ -701,6 +771,7 @@ def __init__(
         super(LabelWeightedSampler, self).__init__(None)
         self.count = 0
         self.curiculum = curiculum
+        self.restrict_to_subset = restrict_to_subset
 
         # Compute label weights (incorporating class frequencies)
         # Directly use labels as numpy array without conversion
diff --git a/tests/test_gene_axis_mapping.py b/tests/test_gene_axis_mapping.py
new file mode 100644
index 0000000..9541d5d
--- /dev/null
+++ b/tests/test_gene_axis_mapping.py
@@ -0,0 +1,92 @@
+from __future__ import annotations
+
+import inspect
+from types import SimpleNamespace
+
+import numpy as np
+import pandas as pd
+
+from scdataloader import DataModule
+from scdataloader.collator import Collator, build_axis_mapping
+from scdataloader.datamodule import LabelWeightedSampler
+
+
+def test_gene_embeddings_is_an_explicit_datamodule_cli_parameter():
+    assert "gene_embeddings" in inspect.signature(DataModule.__init__).parameters
+
+
+def test_build_axis_mapping_preserves_model_gene_order():
+    accepted, model_positions = build_axis_mapping(
+        ["g2", "missing", "g0"], {"g0": 0, "g1": 1, "g2": 2}
+    )
+
+    assert accepted.tolist() == [True, False, True]
+    assert model_positions.tolist() == [2, 0]
+
+
+def test_storage_mapping_reorders_expression_and_emits_storage_index():
+    gene_frame = pd.DataFrame(
+        {"organism": ["org", "org", "org"]}, index=["g0", "g1", "g2"]
+    )
+    mapping = build_axis_mapping(
+        ["g2", "missing", "g0"], {"g0": 0, "g1": 1, "g2": 2}
+    )
+    collator = Collator(
+        organisms=["org"],
+        how="all",
+        org_to_id={"org": 0},
+        valid_genes=["g0", "g1", "g2"],
+        max_len=3,
+        organism_name="organism_ontology_term_id",
+        genedf=gene_frame,
+        storage_gene_mappings=[mapping],
+    )
+    # Collator's existing genedf path does not initialize this derived set.
+    collator.organism_ids = {0}
+
+    result = collator(
+        [
+            {
+                "X": np.array([20.0, 99.0, 10.0]),
+                "organism_ontology_term_id": 0,
+                "_store_idx": 0,
+            }
+        ]
+    )
+
+    assert result["x"].tolist() == [[20.0, 10.0]]
+    assert result["genes"].tolist() == [[2, 0]]
+    assert result["dataset"].tolist() == [0]
+    assert result["depth"].tolist() == [129.0]
+
+
+def test_genes_dict_uses_embedding_subset_order():
+    datamodule = object.__new__(DataModule)
+    datamodule.gene_subset = ["g2", "g0", "g3"]
+    datamodule.dataset = SimpleNamespace(
+        organisms=["org_a", "org_b"],
+        genedf=pd.DataFrame(
+            {"organism": ["org_a", "org_a", "org_b", "org_b"]},
+            index=["g0", "g1", "g2", "g3"],
+        ),
+    )
+
+    assert datamodule.genes_dict == {
+        "org_a": ["g0"],
+        "org_b": ["g2", "g3"],
+    }
+
+
+def test_weighted_sampler_initializes_and_applies_subset_restriction():
+    sampler = LabelWeightedSampler(
+        labels=np.array([0, 0, 1]),
+        num_samples=8,
+        weight_scaler=10,
+        element_weights=np.array([0.1, 0.9, 1.0]),
+        n_workers=1,
+        chunk_size=10,
+        restrict_to_subset=1,
+    )
+
+    assert sampler.restrict_to_subset == 1
+    assert set(iter(sampler)) == {1}