fix(practice-opponents): guard duplicate ids + cover edge cases

SVSim.Bootstrap/Importers/PracticeOpponentImporter.cs

@@ -43,7 +43,12 @@ public class PracticeOpponentImporter
             entry.IsMaintenance = s.IsMaintenance;
             entry.IsCampaignPractice = s.IsCampaignPractice;
 
-            if (ex is null) { context.PracticeOpponents.Add(entry); created++; }
+            if (ex is null)
+            {
+                context.PracticeOpponents.Add(entry);
+                existing[s.PracticeId] = entry;
+                created++;
+            }
             else updated++;
         }
 

SVSim.UnitTests/Importers/PracticeOpponentImporterTests.cs

@@ -38,4 +38,57 @@ public class PracticeOpponentImporterTests
 
         Assert.That(after, Is.EqualTo(before));
     }
+
+    [Test]
+    public async Task Leaves_existing_rows_untouched_when_missing_from_seed()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        // Pre-seed an opponent the production seed file doesn't contain.
+        const int legacyId = 9999;
+        db.PracticeOpponents.Add(new SVSim.Database.Models.PracticeOpponentEntry
+        {
+            Id = legacyId,
+            TextId = "legacy",
+            ClassId = 1,
+            CharaId = 1,
+            DegreeId = 1,
+            AiDeckLevel = 1,
+            AiLogicLevel = 1,
+            AiMaxLife = 20,
+            Battle3dFieldId = "1",
+        });
+        await db.SaveChangesAsync();
+
+        await new PracticeOpponentImporter().ImportAsync(db, SeedDir);
+
+        var legacy = await db.PracticeOpponents.FindAsync(legacyId);
+        Assert.That(legacy, Is.Not.Null, "seed-missing row must be left intact");
+        Assert.That(legacy!.TextId, Is.EqualTo("legacy"), "pre-existing values must not be wiped");
+    }
+
+    [Test]
+    public async Task Skips_rows_with_zero_practice_id()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        // Write a one-row seed with PracticeId=0 to a temp dir and confirm it doesn't insert.
+        string tmp = Path.Combine(Path.GetTempPath(), $"seed-{Guid.NewGuid()}");
+        Directory.CreateDirectory(tmp);
+        try
+        {
+            File.WriteAllText(Path.Combine(tmp, "practice-opponents.json"),
+                "[{\"practice_id\":0,\"text_id\":\"junk\",\"class_id\":1}]");
+
+            await new PracticeOpponentImporter().ImportAsync(db, tmp);
+
+            int count = await db.PracticeOpponents.CountAsync();
+            Assert.That(count, Is.EqualTo(0), "rows with practice_id=0 must not be inserted");
+        }
+        finally { Directory.Delete(tmp, true); }
+    }
 }