Add method for adding new atlases

Author: kaitj

src/neuromaps_prime/graph/core.py

@@ -127,6 +127,33 @@ def add_transform(
             weight=transform.weight,
         )
 
+    def add_atlas(self, atlas: SurfaceAtlas | VolumeAtlas) -> None:
+        """Regiser an atlas to a graph node and a cache entry.
+
+        Args:
+            resource: SurfaceAtlas or VolumeAtlas to add to existing node.
+
+        Raises:
+            TypeError: If atlas is not SurfaceAtlas or VolumeAtlas.
+            ValueError: If atlas space is not present in the graph.
+        """
+        if not isinstance(atlas, (SurfaceAtlas, VolumeAtlas)):
+            raise TypeError(f"Unsupported atlas type: {type(atlas)}")
+
+        node_name = atlas.space
+        if node_name not in self.nodes:
+            raise ValueError(
+                f"Node '{node_name}' not found. Available nodes: {sorted(self.nodes)}"
+            )
+
+        node_data = self.nodes[node_name]["data"]
+        if isinstance(atlas, SurfaceAtlas):
+            node_data.surfaces.append(atlas)
+            self._cache.add_surface_atlas(atlas)
+        else:
+            node_data.volumes.append(atlas)
+            self._cache.add_volume_atlas(atlas)
+
     # Validation
     def validate_spaces(self, source: str, target: str) -> None:
         """Assert that both source and target exist as nodes in the graph.
@@ -323,7 +350,6 @@ def search_surface_transforms(
         )
 
     # Density helpers
-
     def find_common_density(self, mid_space: str, target_space: str) -> str:
         """Find the highest density shared between mid_space and target_space.