refactor(python): migrate all callers to MetaDataLoader class + module shortcuts

Replaces every `from metaobjects.loader.meta_data_loader import load_directory`
import with the new public API (typically `from metaobjects import
MetaDataLoader` + `MetaDataLoader.from_directory(...)`), completing the
loader-unification cutover. Ten call sites updated:

  - tests/conformance/conformance_adapter.py
  - tests/codegen/test_runner.py, test_golden.py
  - tests/unit/test_loader.py, test_loader_bom.py, test_meta_source.py,
    test_one_primary_source.py, test_field_enum.py,
    test_relationship_referential_actions.py, test_common_attrs.py

Full python suite now passes (442 tests), matching the pre-task baseline
plus 25 new tests for the source/loader/shortcut layer. The single
pre-existing `doc-common-attrs-on-all-types` conformance failure is
unchanged (it is a metadata gap, not a loader regression — tracked
elsewhere as a known issue).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: dmealing

server/python/tests/codegen/test_golden.py

@@ -1,7 +1,7 @@
 import importlib.util
 from pathlib import Path
 
-from metaobjects.loader.meta_data_loader import load_directory
+from metaobjects import MetaDataLoader
 from metaobjects.codegen.config import GenConfig
 from metaobjects.codegen.runner import run_gen
 from metaobjects.codegen.generators.entity_model import entity_model
@@ -17,7 +17,7 @@ def _generate(case_dir: Path, out: Path) -> Path:
     meta_dir = out / "meta"
     meta_dir.mkdir(parents=True)
     (meta_dir / "meta.json").write_text((case_dir / "meta.json").read_text())
-    root = load_directory(str(meta_dir)).root
+    root = MetaDataLoader.from_directory(meta_dir).root
     gen_out = out / "gen"
     run_gen(GenConfig(out_dir=str(gen_out)), root, generators=[entity_model()])
     return gen_out

server/python/tests/codegen/test_runner.py

@@ -3,7 +3,7 @@
 
 import pytest
 
-from metaobjects.loader.meta_data_loader import load_directory
+from metaobjects import MetaDataLoader
 from metaobjects.meta.meta_data import MetaData
 from metaobjects.codegen.config import GenConfig
 from metaobjects.codegen.runner import run_gen
@@ -13,7 +13,7 @@
 def _load(meta_dir: Path, doc: dict[str, object]) -> MetaData:
     meta_dir.mkdir(parents=True, exist_ok=True)
     (meta_dir / "meta.json").write_text(json.dumps(doc))
-    return load_directory(str(meta_dir)).root
+    return MetaDataLoader.from_directory(meta_dir).root
 
 
 def test_run_gen_writes_a_model_per_entity(tmp_path: Path) -> None:

server/python/tests/conformance/conformance_adapter.py

@@ -3,9 +3,9 @@
 
 from pathlib import Path
 
+from metaobjects import LoadResult, MetaDataLoader
 from metaobjects.core_types import core_provider
 from metaobjects.documentation import doc_provider
-from metaobjects.loader.meta_data_loader import LoadResult, load_directory
 from metaobjects.meta.meta_data import MetaData
 from metaobjects.serializer_json import canonical_serialize
 
@@ -14,12 +14,12 @@
 
 def load_fixture(input_dir: Path) -> tuple[list[str], list[str], str]:
     """Return (error_codes, warnings, canonical_serialization)."""
-    result = load_directory(str(input_dir), providers=_PROVIDERS)
+    result = MetaDataLoader.from_directory(input_dir, providers=_PROVIDERS)
     codes = [e.code.name for e in result.errors]
     canonical = canonical_serialize(result.root)
     return codes, list(result.warnings), canonical
 
 
 def load_fixture_result(input_dir: Path) -> LoadResult:
     """Return the full LoadResult (including the root node) for script.json checks."""
-    return load_directory(str(input_dir), providers=_PROVIDERS)
+    return MetaDataLoader.from_directory(input_dir, providers=_PROVIDERS)

server/python/tests/unit/test_common_attrs.py

@@ -248,7 +248,7 @@ def test_doc_provider_registers_common_attrs() -> None:
 
 def test_stringarray_desugar_via_common_attr() -> None:
     """A string scalar for a stringArray common attr is desugared to a single-element list."""
-    from metaobjects.loader.meta_data_loader import load_directory
+    from metaobjects import MetaDataLoader
     import json
     import tempfile
     import os
@@ -275,7 +275,7 @@ def test_stringarray_desugar_via_common_attr() -> None:
         path = os.path.join(tmpdir, "meta.acme.json")
         with open(path, "w") as f:
             json.dump(fixture, f)
-        result = load_directory(tmpdir, providers=[core_provider, doc_provider])
+        result = MetaDataLoader.from_directory(tmpdir, providers=[core_provider, doc_provider])
 
     assert not result.errors, f"Unexpected errors: {result.errors}"
 

server/python/tests/unit/test_field_enum.py

@@ -9,9 +9,9 @@
 
 import pytest
 
+from metaobjects import MetaDataLoader
 from metaobjects.core_types import core_provider
 from metaobjects.errors import ErrorCode
-from metaobjects.loader.meta_data_loader import load_directory
 from metaobjects.meta.core.attr.attr_constants import ATTR_SUBTYPE_STRINGARRAY
 from metaobjects.meta.core.field.field_constants import FIELD_ATTR_VALUES, FIELD_SUBTYPE_ENUM
 from metaobjects.meta.core.field.meta_field import MetaField
@@ -34,7 +34,7 @@ def _load(doc: dict) -> tuple[list[str], str]:
     with tempfile.TemporaryDirectory() as tmpdir:
         path = os.path.join(tmpdir, "meta.test.json")
         Path(path).write_text(json.dumps(doc))
-        result = load_directory(tmpdir, providers=[core_provider])
+        result = MetaDataLoader.from_directory(tmpdir, providers=[core_provider])
         codes = [e.code.name for e in result.errors]
         canonical = canonical_serialize(result.root)
         return codes, canonical

server/python/tests/unit/test_loader.py

@@ -1,7 +1,7 @@
 import json
 from pathlib import Path
 
-from metaobjects.loader.meta_data_loader import load_directory
+from metaobjects import MetaDataLoader
 from metaobjects.serializer_json import canonical_serialize
 
 
@@ -14,7 +14,7 @@ def test_load_single_entity_dir(tmp_path: Path) -> None:
             ]}}
         ]}
     }))
-    result = load_directory(str(tmp_path))
+    result = MetaDataLoader.from_directory(tmp_path)
     assert not result.errors
     assert result.root.frozen
     out = json.loads(canonical_serialize(result.root))

server/python/tests/unit/test_loader_bom.py

@@ -4,8 +4,8 @@
 import json
 from pathlib import Path
 
+from metaobjects import MetaDataLoader
 from metaobjects.errors import ErrorCode
-from metaobjects.loader.meta_data_loader import load_directory
 
 
 def _minimal_root_json() -> str:
@@ -40,7 +40,7 @@ def test_bom_prefixed_file_does_not_produce_malformed_json_error(tmp_path: Path)
     bom_file = tmp_path / "meta.items.json"
     bom_file.write_text(bom + _minimal_root_json(), encoding="utf-8")
 
-    result = load_directory(str(tmp_path))
+    result = MetaDataLoader.from_directory(tmp_path)
 
     malformed = [e for e in result.errors if e.code == ErrorCode.ERR_MALFORMED_JSON]
     assert not malformed, (
@@ -54,7 +54,7 @@ def test_bom_prefixed_file_parses_entity(tmp_path: Path) -> None:
     bom_file = tmp_path / "meta.items.json"
     bom_file.write_text(bom + _minimal_root_json(), encoding="utf-8")
 
-    result = load_directory(str(tmp_path))
+    result = MetaDataLoader.from_directory(tmp_path)
 
     assert not result.errors, f"Unexpected errors: {result.errors}"
     entity_names = [c.name for c in result.root.children() if c.name]
@@ -66,6 +66,6 @@ def test_file_without_bom_still_loads(tmp_path: Path) -> None:
     plain_file = tmp_path / "meta.items.json"
     plain_file.write_text(_minimal_root_json(), encoding="utf-8")
 
-    result = load_directory(str(tmp_path))
+    result = MetaDataLoader.from_directory(tmp_path)
 
     assert not result.errors, f"Unexpected errors: {result.errors}"

server/python/tests/unit/test_meta_source.py

@@ -10,8 +10,8 @@
 import tempfile
 from pathlib import Path
 
+from metaobjects import MetaDataLoader
 from metaobjects.core_types import core_provider
-from metaobjects.loader.meta_data_loader import load_directory
 from metaobjects.meta.persistence.source.meta_source import MetaSource
 from metaobjects.meta.persistence.source.source_constants import (
     DEFAULT_SOURCE_KIND,
@@ -173,7 +173,7 @@ def _load(doc: dict) -> tuple[list[str], str]:
     with tempfile.TemporaryDirectory() as tmpdir:
         path = os.path.join(tmpdir, "meta.test.json")
         Path(path).write_text(json.dumps(doc))
-        result = load_directory(tmpdir, providers=[core_provider])
+        result = MetaDataLoader.from_directory(tmpdir, providers=[core_provider])
         codes = [e.code.name for e in result.errors]
         canonical = canonical_serialize(result.root)
         return codes, canonical

server/python/tests/unit/test_one_primary_source.py

@@ -18,15 +18,15 @@
 import tempfile
 from pathlib import Path
 
+from metaobjects import MetaDataLoader
 from metaobjects.core_types import core_provider
-from metaobjects.loader.meta_data_loader import load_directory
 
 
 def _load(doc: dict) -> list[str]:
     with tempfile.TemporaryDirectory() as tmpdir:
         path = os.path.join(tmpdir, "meta.test.json")
         Path(path).write_text(json.dumps(doc))
-        result = load_directory(tmpdir, providers=[core_provider])
+        result = MetaDataLoader.from_directory(tmpdir, providers=[core_provider])
         return [e.code.name for e in result.errors]
 
 

server/python/tests/unit/test_relationship_referential_actions.py

@@ -19,8 +19,8 @@
 import tempfile
 from pathlib import Path
 
+from metaobjects import MetaDataLoader
 from metaobjects.core_types import core_provider
-from metaobjects.loader.meta_data_loader import load_directory
 from metaobjects.meta.core.relationship.meta_relationship import MetaRelationship
 from metaobjects.meta.core.relationship.relationship_constants import (
     ON_DELETE_DEFAULT_BY_SUBTYPE,
@@ -92,7 +92,7 @@ def _load(doc: dict) -> list[str]:
     with tempfile.TemporaryDirectory() as tmpdir:
         path = os.path.join(tmpdir, "meta.test.json")
         Path(path).write_text(json.dumps(doc))
-        result = load_directory(tmpdir, providers=[core_provider])
+        result = MetaDataLoader.from_directory(tmpdir, providers=[core_provider])
         return [e.code.name for e in result.errors]