fix: preserve search input and add choseong lookup

tests/MBN_STOCK_WEBVIEW.LegacyApplication.Tests/LegacyParityStockSearchServiceTests.cs

@@ -66,6 +66,48 @@ public sealed class LegacyParityStockSearchServiceTests
             call => Assert.Equal(string.Empty, call.Spec.Parameters[0].Value));
     }
 
+    [Fact]
+    public async Task InitialConsonantSearch_FiltersOnlyLegacySearchCandidatesInProviderOrder()
+    {
+        var executor = new RecordingExecutor(new Dictionary<string, DataTable>
+        {
+            ["LEGACY_PARITY_KOSPI_MASTER"] = Table(
+                ("삼성전자", "005930")),
+            ["LEGACY_PARITY_KOSDAQ_MASTER"] = Table(
+                ("삼성중공업", "010140")),
+            ["LEGACY_PARITY_NXT_KOSPI_MASTER"] = Table(
+                ("삼성전자(NXT)", "005930"),
+                ("삼성화재(NXT)", "000810")),
+            ["LEGACY_PARITY_NXT_KOSDAQ_MASTER"] = Table(
+                ("카카오게임즈(NXT)", "293490")),
+            ["LEGACY_PARITY_KOSPI"] = Table(
+                ("삼성전자", "005930"),
+                ("서울반도체", "046890")),
+            ["LEGACY_PARITY_KOSDAQ"] = Table(
+                ("삼성중공업", "010140")),
+            ["LEGACY_PARITY_NXT_KOSPI"] = Table(
+                ("삼성전자(NXT)", "005930")),
+            ["LEGACY_PARITY_NXT_KOSDAQ"] = Table()
+        });
+        var service = new LegacyParityStockSearchService(executor);
+
+        var result = await service.SearchAsync("ㅅㅅ");
+
+        Assert.Equal(
+            ["삼성전자", "삼성중공업", "삼성전자(NXT)"],
+            result.DisplayNames);
+        Assert.DoesNotContain("삼성화재(NXT)", result.DisplayNames);
+        Assert.NotNull(result.ResolveLastByDisplayName("삼성화재(NXT)"));
+        Assert.Equal(8, executor.Calls.Count);
+        Assert.All(
+            executor.Calls.Where(call => !call.TableName.EndsWith("_MASTER", StringComparison.Ordinal)),
+            call => Assert.Equal(string.Empty, call.Spec.Parameters[0].Value));
+        Assert.Contains(
+            executor.Calls,
+            call => call.TableName == "LEGACY_PARITY_NXT_KOSPI" &&
+                call.Spec.Sql.Contains("N_ONLINE", StringComparison.Ordinal));
+    }
+
     private static DataTable Table(params (string Name, string Code)[] rows)
     {
         var table = new DataTable();