Enhance world simulation and API functionality; implement clock management improvements, ensure proper handling of world states during updates, and refine data persistence methods to prevent resurrecting deleted worlds.

tests/TheLivingWorld.Tests/WorldStoreTests.cs

@@ -47,6 +47,39 @@ public sealed class WorldStoreTests : IDisposable
         Assert.Equal(1, await _store.CountAsync());
     }
 
+    [Fact]
+    public async Task TryUpdateSummaryAsync_writes_over_an_existing_state_file()
+    {
+        var summary = Summary("alpha-11111111", "Alpha");
+        await _store.SaveSummaryAsync(summary);
+
+        Assert.True(await _store.TryUpdateSummaryAsync(summary with { Name = "Renamed" }));
+        Assert.Equal("Renamed", (await _store.GetSummaryAsync(summary.Id))?.Name);
+    }
+
+    [Fact]
+    public async Task TryUpdateSummaryAsync_refuses_to_recreate_a_deleted_world()
+    {
+        var summary = Summary("alpha-11111111", "Alpha");
+        await _store.SaveSummaryAsync(summary);
+        Assert.True(_store.Delete(summary.Id));
+
+        Assert.False(await _store.TryUpdateSummaryAsync(summary));
+        Assert.False(Directory.Exists(Path.Combine(_root, summary.Id)));
+        Assert.Equal(0, await _store.CountAsync());
+    }
+
+    [Fact]
+    public async Task SaveSummaryAsync_leaves_no_scratch_files_behind()
+    {
+        var summary = Summary("alpha-11111111", "Alpha");
+        await _store.SaveSummaryAsync(summary);
+        await _store.SaveSummaryAsync(summary with { Name = "Alpha again" });
+
+        var files = Directory.GetFiles(Path.Combine(_root, summary.Id));
+        Assert.Equal(["state.json"], files.Select(static path => Path.GetFileName(path)).Order().ToArray()!);
+    }
+
     private static WorldSummaryDto Summary(string id, string name) => new()
     {
         Id = id,