refactor(bootstrap): add seed loader + extractor scaffolding

SVSim.Bootstrap/Importers/SeedLoader.cs

@@ -0,0 +1,42 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace SVSim.Bootstrap.Importers;
+
+/// <summary>
+/// Reads a JSON seed file under <c>SVSim.Bootstrap/Data/seeds/</c>. Replaces ImporterBase.LoadCapture.
+/// Files are produced by extractors in <c>data_dumps/extract/</c>; the bootstrap project does not
+/// transform wire formats. Missing files are non-fatal (returns empty/null) — caller decides.
+/// </summary>
+public static class SeedLoader
+{
+    private static readonly JsonSerializerOptions Options = new()
+    {
+        PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower,
+        NumberHandling = JsonNumberHandling.AllowReadingFromString,
+        ReadCommentHandling = JsonCommentHandling.Skip,
+        AllowTrailingCommas = true,
+    };
+
+    public static List<T> LoadList<T>(string path)
+    {
+        if (!File.Exists(path))
+        {
+            Console.Error.WriteLine($"[SeedLoader] Missing seed file: {path}");
+            return new List<T>();
+        }
+        using var fs = File.OpenRead(path);
+        return JsonSerializer.Deserialize<List<T>>(fs, Options) ?? new List<T>();
+    }
+
+    public static T? LoadObject<T>(string path) where T : class
+    {
+        if (!File.Exists(path))
+        {
+            Console.Error.WriteLine($"[SeedLoader] Missing seed file: {path}");
+            return null;
+        }
+        using var fs = File.OpenRead(path);
+        return JsonSerializer.Deserialize<T>(fs, Options);
+    }
+}

SVSim.Bootstrap/SVSim.Bootstrap.csproj

@@ -27,6 +27,9 @@
     <Content Include="Data\story\*.json">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <None Update="Data\seeds\**\*.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
   </ItemGroup>
 
   <ItemGroup>

SVSim.UnitTests/Importers/SeedLoaderTests.cs

@@ -0,0 +1,39 @@
+using SVSim.Bootstrap.Importers;
+
+namespace SVSim.UnitTests.Importers;
+
+public class SeedLoaderTests
+{
+    private sealed record Row(int Id, string Name);
+
+    [Test]
+    public void LoadList_returns_empty_when_file_missing()
+    {
+        string path = Path.Combine(Path.GetTempPath(), $"missing-{Guid.NewGuid()}.json");
+        var rows = SeedLoader.LoadList<Row>(path);
+        Assert.That(rows, Is.Empty);
+    }
+
+    [Test]
+    public void LoadList_deserializes_snake_case_array()
+    {
+        string path = Path.Combine(Path.GetTempPath(), $"seed-{Guid.NewGuid()}.json");
+        File.WriteAllText(path, "[{\"id\":1,\"name\":\"a\"},{\"id\":2,\"name\":\"b\"}]");
+        try
+        {
+            var rows = SeedLoader.LoadList<Row>(path);
+            Assert.That(rows, Has.Count.EqualTo(2));
+            Assert.That(rows[0].Id, Is.EqualTo(1));
+            Assert.That(rows[1].Name, Is.EqualTo("b"));
+        }
+        finally { File.Delete(path); }
+    }
+
+    [Test]
+    public void LoadObject_returns_null_when_file_missing()
+    {
+        string path = Path.Combine(Path.GetTempPath(), $"missing-{Guid.NewGuid()}.json");
+        var row = SeedLoader.LoadObject<Row>(path);
+        Assert.That(row, Is.Null);
+    }
+}