Merge nucleic/warm-north-vole-pf37 into dev

NucleicProtocol.Interop/ProtocolProjection.cs

@@ -0,0 +1,41 @@
+namespace NucleicProtocol.Interop;
+
+/// Managed ownership wrapper for the shared Swift transcript projector.
+public interface ITranscriptProjector : IDisposable
+{
+    ProjectionDiff Apply(string hostMessageJson);
+}
+
+public sealed class ProtocolProjection : ITranscriptProjector
+{
+    private readonly object gate = new();
+    private readonly INativeProtocol native;
+    private nint handle;
+
+    public ProtocolProjection(INativeProtocol? native = null)
+    {
+        this.native = native ?? PInvokeNativeProtocol.Instance;
+        handle = this.native.ProjectionCreate();
+        if (handle == 0) throw new InvalidOperationException("could not create transcript projection");
+    }
+
+    public ProjectionDiff Apply(string hostMessageJson)
+    {
+        lock (gate)
+        {
+            ObjectDisposedException.ThrowIf(handle == 0, this);
+            var value = native.ProjectionApply(handle, hostMessageJson);
+            return ProjectionDiff.Parse(native.CopyAndFreeString(value));
+        }
+    }
+
+    public void Dispose()
+    {
+        lock (gate)
+        {
+            if (handle == 0) return;
+            native.ProjectionFree(handle);
+            handle = 0;
+        }
+    }
+}