From ebc3165389da094f455344ee741cd25f36325d7e Mon Sep 17 00:00:00 2001
From: Sun Haoyuan <58774225+Shy7777@users.noreply.github.com>
Date: Tue, 22 Sep 2026 17:50:44 +0800
Subject: [PATCH] Python: preserve integer precision in in-memory Hamming
 search

---
 .../core/agent_framework/_in_memory.py        |  9 +++--
 .../core/tests/core/test_in_memory.py         | 33 +++++++++++++++++++
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/python/packages/core/agent_framework/_in_memory.py b/python/packages/core/agent_framework/_in_memory.py
index 01b5ef6d448..cc8f8046cb7 100644
--- a/python/packages/core/agent_framework/_in_memory.py
+++ b/python/packages/core/agent_framework/_in_memory.py
@@ -96,7 +96,7 @@ def _numeric_vector(value: Any, *, field_name: str) -> tuple[float, ...]:
         number = float(item)
         if not math.isfinite(number):
             raise ValueError(f"Vector field '{field_name}' must contain only finite numbers.")
-        vector.append(number)
+        vector.append(item)
     if not vector:
         raise ValueError(f"Vector field '{field_name}' cannot be empty.")
     return tuple(vector)
@@ -115,6 +115,11 @@ def _paired_vectors(left: Vector, right: Vector) -> tuple[tuple[float, ...], tup
 
 def _calculate_score(left: Vector, right: Vector, distance_function: DistanceFunction) -> float:
     left_values, right_values = _paired_vectors(left, right)
+    if distance_function == "hamming":
+        # Compare coordinates before float conversion can round distinct large integers to the same value.
+        return sum(a != b for a, b in zip(left_values, right_values, strict=True)) / len(left_values)
+    left_values = tuple(float(value) for value in left_values)
+    right_values = tuple(float(value) for value in right_values)
     if distance_function in ("cosine_similarity", "cosine_distance", "DEFAULT"):
         left_scale = max(abs(value) for value in left_values)
         right_scale = max(abs(value) for value in right_values)
@@ -140,8 +145,6 @@ def _calculate_score(left: Vector, right: Vector, distance_function: DistanceFun
         score = sum((a - b) * (a - b) for a, b in zip(left_values, right_values, strict=True))
     elif distance_function == "manhattan":
         score = sum(abs(a - b) for a, b in zip(left_values, right_values, strict=True))
-    elif distance_function == "hamming":
-        score = sum(a != b for a, b in zip(left_values, right_values, strict=True)) / len(left_values)
     else:
         raise NotImplementedError(f"Distance function '{distance_function}' is not supported by InMemoryCollection.")
     if not math.isfinite(score):
diff --git a/python/packages/core/tests/core/test_in_memory.py b/python/packages/core/tests/core/test_in_memory.py
index 6477548c689..1253a189519 100644
--- a/python/packages/core/tests/core/test_in_memory.py
+++ b/python/packages/core/tests/core/test_in_memory.py
@@ -531,6 +531,39 @@ async def test_hamming_scores_and_thresholds_use_mismatch_proportions() -> None:
     ]
 
 
+@pytest.mark.parametrize(
+    ("vector_type", "coordinate"),
+    [("int64", 2**53), ("int64", -(2**53) - 1), ("uint64", 2**64 - 2)],
+)
+@pytest.mark.parametrize("threshold", [None, 0.0])
+async def test_hamming_preserves_large_integer_coordinates(
+    vector_type: str, coordinate: int, threshold: float | None
+) -> None:
+    definition = VectorStoreCollectionDefinition(
+        [
+            VectorStoreField("key", name="id"),
+            VectorStoreField("vector", name="vector", type_=vector_type, dimensions=2, distance_function="hamming"),
+        ],
+        collection_name="integer-hamming",
+    )
+    collection: InMemoryCollection[str, dict[str, Any]] = InMemoryCollection(dict, definition=definition)
+    await collection.ensure_collection_exists()
+    await collection.upsert(
+        [
+            {"id": "different", "vector": [coordinate + 1, 0]},
+            {"id": "same", "vector": [coordinate, 0]},
+        ],
+        generate_vectors=False,
+    )
+
+    results = await collection.search(vector=[coordinate, 0], score_threshold=threshold)
+
+    expected = [("same", 0.0)]
+    if threshold is None:
+        expected.append(("different", 0.5))
+    assert [(result["record"]["id"], result["score"]) async for result in results] == expected
+
+
 @pytest.mark.parametrize("contents", ["empty", "missing_vector", "filtered_out"])
 @pytest.mark.parametrize("score_threshold", [None, 0.5])
 async def test_unsupported_distance_is_rejected_independently_of_records(