fix(python): avoid full-width bitpacking panic

python/Cargo.toml

@@ -20,6 +20,9 @@ arrow = { workspace = true, features = ["pyarrow"] }
 async-trait.workspace = true
 bytes.workspace = true
 lancedb.workspace = true
+# Maturin includes direct path dependencies in source distributions. The
+# workspace patch also applies to transitive Lance writer dependencies.
+lance-encoding = { path = "../vendor/lance-encoding", version = "=13.0.0-beta.12" }
 datafusion-common.workspace = true
 lance-core.workspace = true
 lance-namespace.workspace = true

python/python/tests/test_table.py

@@ -6,6 +6,7 @@ import ctypes
 import gc
 import json
 import os
+import random
 import sys
 import threading
 import warnings
@@ -412,6 +413,21 @@ def test_create_table_rejects_single_dictionary(mem_db: DBConnection):
     )
 
 
+def test_create_table_with_negative_int64_dictionary_tail(tmp_db: DBConnection):
+    # A dictionary of negative values can have a full 64-bit width and a
+    # partial 1024-value chunk. The writer must not choose out-of-line
+    # bitpacking, which requires at least one bit of savings.
+    rng = random.Random(42)
+    values = list(range(-800, 800))
+    rows = [{"f0": values[rng.randrange(len(values))]} for _ in range(9216)]
+    schema = pa.schema([pa.field("f0", pa.int64(), nullable=True)])
+
+    table = tmp_db.create_table("negative_int64_tail", data=rows, schema=schema)
+
+    assert table.count_rows() == len(rows)
+    assert table.to_arrow().column("f0").to_pylist() == [row["f0"] for row in rows]
+
+
 def test_empty_table(mem_db: DBConnection):
     schema = pa.schema(
         [