Terminal: buy-average price per coin in Poinbase and Web3; drop the price line on the Poinbase card

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

tests/Decentralized.Domain.Tests/Program.cs

@@ -248,6 +248,20 @@ internal static class Program
             Check(hi.Price <= 300 + 1e-9, $"上限 3 倍：{hi.Price:0.0}");
         });
 
+        Test("钱包：买入均价按买入记录算，卖出和转出按比例减少，挖出的币不计入", () =>
+        {
+            var w = new Wallet { Address = "x" };
+            w.Add("PSC", 10);                       // 挖出的 10 个，无买入记录
+            Check(w.AvgBuy("PSC") == null, "没有买入记录时没有均价");
+            w.Add("PSC", 5); w.RecordBuy("PSC", 5, 400);
+            w.Add("PSC", 5); w.RecordBuy("PSC", 5, 600);
+            Check(Near(w.AvgBuy("PSC").Value, 100, 1e-9), "买 5 个花 400 + 买 5 个花 600：均价 100");
+            w.Add("PSC", -10);                      // 卖掉一半（20 个里的 10 个）
+            Check(Near(w.AvgBuy("PSC").Value, 100, 1e-9) && Near(w.BuyQty["PSC"], 5, 1e-9), "卖出后均价不变，买入记录按比例减少");
+            w.Add("PSC", -10);
+            Check(w.AvgBuy("PSC") == null, "清仓后记录清除");
+        });
+
         Test("市场：减半抬高价格锚（逐日靠拢），减半前一周有预期行情", () =>
         {
             Check(Near(Market.SupplyTarget(10, Tuning.BlockReward), 1.0, 1e-9), "减半前很远：目标因子 1");