Make Timestamp a special SATS type

crates/bindings-csharp/BSATN.Runtime.Tests/Tests.cs

@@ -143,12 +143,28 @@ public static void NonHexStrings()
     [Fact]
     public static void TimestampConversionChecks()
     {
-        ulong us = 1737582793990639;
-        var time = ScheduleAt.DateTimeOffsetFromMicrosSinceUnixEpoch(us);
+        var us = 1737582793990639L;
 
+        var time = ScheduleAt.DateTimeOffsetFromMicrosSinceUnixEpoch(us);
         Assert.Equal(ScheduleAt.ToMicrosecondsSinceUnixEpoch(time), us);
 
         var interval = ScheduleAt.TimeSpanFromMicroseconds(us);
         Assert.Equal(ScheduleAt.ToMicroseconds(interval), us);
+
+        var stamp = new Timestamp(us);
+        var dto = (DateTimeOffset)stamp;
+        var stamp_ = (Timestamp)dto;
+        Assert.Equal(stamp, stamp_);
+
+        var duration = new TimeDuration(us);
+        var timespan = (TimeSpan)duration;
+        var duration_ = (TimeDuration)timespan;
+        Assert.Equal(duration, duration_);
+
+        var newIntervalUs = 333L;
+        var newInterval = new TimeDuration(newIntervalUs);
+        var laterStamp = stamp + newInterval;
+        Assert.Equal(laterStamp.MicrosecondsSinceUnixEpoch, us + newIntervalUs);
+        Assert.Equal(laterStamp.TimeDurationSince(stamp), newInterval);
     }
 }

crates/bindings-csharp/BSATN.Runtime/BSATN.Runtime.csproj

@@ -11,6 +11,8 @@
     <!-- Note: the binary produced by this package is used in Unity too, which is limited to .NET Standard 2.1. -->
     <TargetFrameworks>netstandard2.1;net8.0</TargetFrameworks>
     <RootNamespace>SpacetimeDB</RootNamespace>
+    <!-- You can enable this when debugging codegen problems. Outputs in obj/debug/[version]/generated. -->
+    <!-- <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles> -->
   </PropertyGroup>
 
   <ItemGroup>