diff --git a/python/packages/core/agent_framework/_vectors.py b/python/packages/core/agent_framework/_vectors.py
index 1993d4dc75..142a709b78 100644
--- a/python/packages/core/agent_framework/_vectors.py
+++ b/python/packages/core/agent_framework/_vectors.py
@@ -572,16 +572,33 @@ def encode(value: Any) -> Mapping[str, Any]:
     return encode
 
 
+def _pydantic_validation_key(name: str, field_info: Any) -> str:
+    """Return the key that feeds one model field from a mapping keyed by field name.
+
+    A string validation alias (which ``alias=`` also installs) or a string model alias is the key
+    Pydantic accepts, so it is used unchanged. ``AliasChoices`` declares several accepted aliases and
+    validates on any one of them, so the first string choice is used; keying such a field by its own
+    name only validates when the model also allows population by name, which declaring an alias does
+    not require. Nested ``AliasPath`` aliases keep the previous field-name fallback.
+    """
+    validation_alias = getattr(field_info, "validation_alias", None)
+    if isinstance(validation_alias, str):
+        return validation_alias
+    choices = getattr(validation_alias, "choices", None)
+    if isinstance(choices, Sequence) and not isinstance(choices, str):
+        for choice in cast("Sequence[Any]", choices):
+            if isinstance(choice, str):
+                return choice
+    alias = getattr(field_info, "alias", None)
+    return alias if isinstance(alias, str) else name
+
+
 def _default_vector_model_decoder(record_type: type[Any]) -> VectorModelDecoder:
     if issubclass(record_type, BaseModel):
 
         def decode_pydantic(value: Mapping[str, Any]) -> Any:
             validation_value = {
-                field.validation_alias
-                if isinstance(field.validation_alias, str)
-                else field.alias
-                if isinstance(field.alias, str)
-                else name: value[name]
+                _pydantic_validation_key(name, field): value[name]
                 for name, field in record_type.model_fields.items()
                 if name in value
             }
diff --git a/python/packages/core/tests/core/test_vectors.py b/python/packages/core/tests/core/test_vectors.py
index 34d0cd8793..a79ca1cf01 100644
--- a/python/packages/core/tests/core/test_vectors.py
+++ b/python/packages/core/tests/core/test_vectors.py
@@ -15,7 +15,7 @@
 
 import msgspec
 import pytest
-from pydantic import BaseModel
+from pydantic import AliasChoices, BaseModel
 from pydantic import Field as PydanticField
 
 from agent_framework import (
@@ -721,6 +721,38 @@ class AliasedRecord(BaseModel):
     assert restored.id == "one"
 
 
+async def test_pydantic_alias_choices_records_round_trip_through_a_collection() -> None:
+    # The encoder stores field names, so the decoder feeds the first declared alias choice back to
+    # Pydantic. Falling back to the field name only validates when the model also populates by name,
+    # which an alias-only field does not, so the record read back failed after a successful upsert.
+    @vectorstoremodel(collection_name="alias_choices_records")
+    class AliasChoiceRecord(BaseModel):
+        id: Annotated[
+            str,
+            PydanticField(validation_alias=AliasChoices("record_id", "document_id")),
+            VectorStoreField("key"),
+        ]
+        text: Annotated[str, VectorStoreField("data")]
+        embedding: Annotated[list[float], VectorStoreField("vector", dimensions=2)] = PydanticField(
+            default_factory=list
+        )
+
+    collection: InMemoryCollection[str, AliasChoiceRecord] = InMemoryCollection(AliasChoiceRecord)
+    await collection.ensure_collection_exists()
+
+    keys = await collection.upsert(
+        [AliasChoiceRecord(record_id="one", text="plain sample", embedding=[0.25, 0.75])],
+        generate_vectors=False,
+    )
+    restored = await collection.get(keys, include_vectors=True)
+
+    assert keys == ["one"]
+    assert len(restored) == 1
+    assert restored[0].id == "one"
+    assert restored[0].text == "plain sample"
+    assert restored[0].embedding == [0.25, 0.75]
+
+
 async def test_collection_serializes_records_and_generates_vectors() -> None:
     embedding_client = MockEmbeddingClient()
     collection = MockCollection(embedding_generator=embedding_client)