graph/methods/fetchers.py — deleted
GraphFetchers was a pure passthrough onto GraphCache with identical signatures. Its filtered list methods (fetch_surface_atlases, etc.) were moved directly onto GraphCache as get_surface_atlases, get_surface_transforms, get_volume_atlases, get_volume_transforms.

graph/methods/cache.py — merged + extended
Absorbed all fetcher methods (renamed fetch_* → get_* for consistency with the existing single-item getters), and gained require_surface_atlas — the raising variant that both ops classes previously duplicated privately.
Moved to graph/cache.py and deleted graph/methods

graph/models.py — simplified
Removed the ABC base and abstractmethod decorator. All four subclasses implemented fetch() identically as return self.file_path, so the method now lives once on the concrete Resource base.

graph/builder.py — de-duplicated
Four _parse_* methods (two for atlases, two for transforms) had the same nested-iteration shape. Collapsed to _parse_surface_resources and _parse_volume_resources, each accepting the target model class and a fixed_fields dict. The name prefix logic is derived from fixed_fields uniformly.

graph/utils.py — fetchers → cache
GraphUtils previously held a fetchers: GraphFetchers reference. Now holds cache: GraphCache directly and calls cache.get_surface_atlases / cache.get_surface_transforms.

graph/transforms/surface.py — fetchers → cache, _require_surface_atlas removed
SurfaceTransformOps dropped the fetchers field and the duplicated _require_surface_atlas. All lookups now go through self.cache.get_* or self.cache.require_surface_atlas.

graph/transforms/volume.py — same treatment
VolumeTransformOps dropped fetchers and its own copy of _require_surface_atlas. The _project_volume_to_surface ribbon dict comprehension replaced the sequential for-loop over ("white", "pial").

graph/core.py — fetchers removed, data_dir typed
self.fetchers is gone. The data_dir walrus-operator pattern gives it a clean Path | None type at construction. All fetch_* public methods now call self._cache.get_* directly.

Tests — fetchers → cache, fetch_* → get_*/require_* throughout. The two _require_surface_atlas tests moved from test_surf_to_surf.py to a new TestGraphCacheRequire class in test_graph.py. The vol-to-surf tests that simulated a miss via return_value=None were updated to use side_effect=ValueError(...) since require_surface_atlas raises rather than returning None.

_Unit tests co-written and optimized by by Claude Code_