fix: show risk amount only in full-margin mode across four exchanges

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_position_sizing_risk_display.py

@@ -0,0 +1,34 @@
+"""全仓 / 以损定仓 风险展示文案。"""
+from __future__ import annotations
+
+import sys
+import unittest
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(ROOT))
+
+from position_sizing_lib import (  # noqa: E402
+    format_risk_display_text,
+    risk_percent_for_storage,
+)
+
+
+class TestPositionSizingRiskDisplay(unittest.TestCase):
+    def test_full_margin_shows_amount_only(self):
+        self.assertEqual(
+            format_risk_display_text("full_margin", 1.0, 2.58, decimals=2),
+            "2.58U",
+        )
+        self.assertIsNone(risk_percent_for_storage("full_margin", 1.0))
+
+    def test_risk_mode_shows_percent_and_amount(self):
+        self.assertEqual(
+            format_risk_display_text("risk", 2.0, 10.5, decimals=2),
+            "2%≈10.5U",
+        )
+        self.assertEqual(risk_percent_for_storage("risk", 2.0), 2.0)
+
+
+if __name__ == "__main__":
+    unittest.main()