fix: make entropy_compress backend constructible

src/lightmem/configs/pre_compressor/base.py

@@ -10,7 +10,7 @@ class PreCompressorConfig(BaseModel):
 
     _model_configs: ClassVar[Dict[str, str]] = {
         "llmlingua-2": "lightmem.configs.pre_compressor.llmlingua_2.LlmLingua2Config",  
-        "entropy_compress": "lightmem.configs.pre_compressor.entropy_compress.EntropyCompressor"
+        "entropy_compress": "lightmem.configs.pre_compressor.entropy_compress.EntropyCompressorConfig"
     }
 
     configs: Dict[str, Any] = Field(
@@ -47,4 +47,4 @@ def load_config_class(self) -> 'PreCompressorConfig':
 
         except (ImportError, AttributeError) as e:
             raise ValueError(f"Could not load config class '{config_path}': {e}")
-        return self
+        return self

src/lightmem/factory/pre_compressor/factory.py

@@ -5,7 +5,7 @@
 class PreCompressorFactory:
     _MODEL_MAPPING: Dict[str, str] = {
         "llmlingua-2": "lightmem.factory.pre_compressor.llmlingua_2.LlmLingua2Compressor",
-        "entropy_compress": "lightmem.factory.pre_compressor.entropy_compress.",
+        "entropy_compress": "lightmem.factory.pre_compressor.entropy_compress.EntropyCompressor",
     }
 
     @classmethod
@@ -53,4 +53,4 @@ def from_config(cls, config: PreCompressorConfig):
         except Exception as e:
             raise ValueError(
                 f"Failed to instantiate {model_name} compressor: {str(e)}"
-            ) from e
+            ) from e

tests/test_pre_compressor_factory.py

@@ -0,0 +1,37 @@
+from types import SimpleNamespace
+
+from lightmem.configs.pre_compressor.base import PreCompressorConfig
+from lightmem.configs.pre_compressor.entropy_compress import EntropyCompressorConfig
+from lightmem.factory.pre_compressor.factory import PreCompressorFactory
+
+
+def test_entropy_compressor_config_resolves_to_its_config_class():
+    config = PreCompressorConfig(model_name="entropy_compress")
+
+    assert isinstance(config.configs, EntropyCompressorConfig)
+
+
+def test_entropy_compressor_factory_resolves_to_its_implementation(monkeypatch):
+    compressor_config = object()
+    imported = {}
+
+    class FakeEntropyCompressor:
+        def __init__(self, config=None):
+            self.config = config
+
+    def fake_import_module(module_path):
+        imported["module_path"] = module_path
+        return SimpleNamespace(EntropyCompressor=FakeEntropyCompressor)
+
+    monkeypatch.setattr(
+        "lightmem.factory.pre_compressor.factory.import_module",
+        fake_import_module,
+    )
+
+    compressor = PreCompressorFactory.from_config(
+        SimpleNamespace(model_name="entropy_compress", configs=compressor_config)
+    )
+
+    assert imported["module_path"] == "lightmem.factory.pre_compressor.entropy_compress"
+    assert isinstance(compressor, FakeEntropyCompressor)
+    assert compressor.config is compressor_config