Fix security list pre-close decoding

tests/fixtures/security_list.json

@@ -3,6 +3,6 @@
   "first": {
     "code": "999999",
     "name": "上证指数",
-    "pre_close": 11654847.33
+    "pre_close": 3966.171142578125
   }
-}
+}

tests/unit/test_commands_offline.py

@@ -7,6 +7,7 @@ fixtures/ 目录下每个 .hex 文件是一次真实服务器响应的 body（
 from __future__ import annotations
 
 import pathlib
+import struct
 
 FIXTURES = pathlib.Path(__file__).parent.parent / "fixtures"
 
@@ -50,13 +51,37 @@ def test_security_list_parse():
     r0 = records[0]
     assert r0.code == "999999"
     assert r0.name == "上证指数"
-    # pre_close is a float; the index level is stored ×100 and has many decimal places
-    assert abs(r0.pre_close - 11654847.33) < 1.0
+    assert abs(r0.pre_close - 3966.171142578125) < 0.01
 
     # _raw present and non-empty for every record
     assert all(len(r._raw) > 0 for r in records)
 
 
+def test_security_list_pre_close_uses_tdx_float_for_a_share():
+    from xmtdx.commands.security_list import GetSecurityListCmd
+    from xmtdx.models.enums import Market
+
+    body = (
+        struct.pack("<H", 1)
+        + struct.pack(
+            "<6sH8s4sBI4s",
+            b"600000",
+            100,
+            "\u6d66\u53d1\u94f6\u884c".encode("gbk"),
+            b"\x00\x00\x00\x00",
+            2,
+            0x411B851F,
+            b"\x00\x00\x00\x00",
+        )
+    )
+
+    record = GetSecurityListCmd(Market.SH, 24000).parse_response(body)[0]
+
+    assert record.code == "600000"
+    assert record.name == "浦发银行"
+    assert abs(record.pre_close - 9.72) < 0.01
+
+
 def test_security_list_gbk_no_crash():
     """Bug #2 修复验证：GBK 解码不崩溃，所有记录均有 code。"""
     from xmtdx.commands.security_list import GetSecurityListCmd