diff --git a/tests/unit/test_embedding_client_fallback.py b/tests/unit/test_embedding_client_fallback.py
new file mode 100644
index 0000000..816cde8
--- /dev/null
+++ b/tests/unit/test_embedding_client_fallback.py
@@ -0,0 +1,52 @@
+import asyncio
+
+import pytest
+
+from aci.infrastructure.embedding import OpenAIEmbeddingClient, RetryConfig
+from aci.infrastructure.embedding.errors import BatchSizeError, NonRetryableError
+
+
+def test_embed_with_fallback_skips_oversized_single_item() -> None:
+    texts = ["ok-1", "oversized", "ok-2"]
+
+    client = OpenAIEmbeddingClient(
+        api_url="https://api.example.com/embeddings",
+        api_key="test-key",
+        dimension=4,
+        batch_size=2,
+        retry_config=RetryConfig(max_retries=0, enable_batch_fallback=True, min_batch_size=1),
+    )
+
+    async def fake_embed_single_batch(batch: list[str]) -> list[list[float]]:
+        if "oversized" in batch:
+            raise BatchSizeError("Token limit exceeded")
+        return [[float(i)] * 4 for i, _ in enumerate(batch, start=1)]
+
+    client._embed_single_batch = fake_embed_single_batch  # type: ignore[method-assign]
+
+    embeddings = asyncio.run(client.embed_batch(texts))
+
+    assert len(embeddings) == len(texts)
+    assert embeddings[0] == [1.0, 1.0, 1.0, 1.0]
+    assert embeddings[1] == [0.0, 0.0, 0.0, 0.0]
+    assert embeddings[2] == [1.0, 1.0, 1.0, 1.0]
+
+
+def test_embed_with_fallback_still_raises_when_disabled() -> None:
+    client = OpenAIEmbeddingClient(
+        api_url="https://api.example.com/embeddings",
+        api_key="test-key",
+        dimension=4,
+        batch_size=2,
+        retry_config=RetryConfig(max_retries=0, enable_batch_fallback=False, min_batch_size=1),
+    )
+
+    async def fake_embed_single_batch(_: list[str]) -> list[list[float]]:
+        raise BatchSizeError("Token limit exceeded")
+
+    client._embed_single_batch = fake_embed_single_batch  # type: ignore[method-assign]
+
+    with pytest.raises(NonRetryableError) as exc_info:
+        asyncio.run(client.embed_batch(["oversized"]))
+
+    assert "fallback is disabled" in str(exc_info.value).lower()