diff --git a/arcllm/__init__.py b/arcllm/__init__.py
index 4647f80..debf79c 100644
--- a/arcllm/__init__.py
+++ b/arcllm/__init__.py
@@ -69,7 +69,7 @@
 
 from __future__ import annotations
 
-__version__ = "0.4.1"
+__version__ = "0.4.2"
 __all__ = [
     "APIConnectionError",
     "APIError",
diff --git a/arcllm/types.py b/arcllm/types.py
index fbb4412..8091392 100644
--- a/arcllm/types.py
+++ b/arcllm/types.py
@@ -427,11 +427,17 @@ def model_dump(self) -> dict[str, Any]:
 
 
 class EmbeddingResponse(msgspec.Struct):
-    """Response from an embedding request."""
+    """Response from an embedding request.
 
-    model: str
-    data: list[EmbeddingData]
-    usage: EmbeddingUsage
+    All fields default — matches the litellm-compat contract where test
+    fixtures construct ``EmbeddingResponse()`` with no args and populate
+    fields after the fact. Adapters always set every field on real
+    responses, so this is purely for caller ergonomics.
+    """
+
+    model: str = ""
+    data: list[EmbeddingData] = []
+    usage: EmbeddingUsage | None = None
     object: str = "list"
 
     def model_dump(self) -> dict[str, Any]:
@@ -439,7 +445,7 @@ def model_dump(self) -> dict[str, Any]:
         return {
             "model": self.model,
             "data": [d.model_dump() for d in self.data],
-            "usage": self.usage.model_dump(),
+            "usage": self.usage.model_dump() if self.usage is not None else None,
             "object": self.object,
         }
 
diff --git a/pyproject.toml b/pyproject.toml
index 0b7db88..d46cbc8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "arcllm-sdk"
-version = "0.4.1"
+version = "0.4.2"
 description = "The arc connecting you to every LLM. Minimal dependencies, maximum performance."
 readme = "README.md"
 license = "Apache-2.0"