feat(codegen): validate contracts and unify Unity weaving

Editor/Core/ShrinkAssemblyWeaver.cs

@@ -57,6 +57,14 @@ public static class ShrinkAssemblyWeaver
 
             var module = assembly.MainModule;
             var marker = FindType(module, "ShrinkSDK.Runtime.ShrinkCodeGenWovenAttribute", "ShrinkRuntime.Abstractions");
+            // Unity passes transitive reference paths even when C# emitted no direct reference.
+            // All Unity postprocessors must see the same marker before another pass runs.
+            if (marker == null)
+            {
+                var runtime = resolver.Resolve(new AssemblyNameReference("ShrinkRuntime.Abstractions", new System.Version(0, 0, 0, 0)));
+                var definition = runtime?.MainModule.GetType("ShrinkSDK.Runtime.ShrinkCodeGenWovenAttribute");
+                if (definition != null) marker = module.ImportReference(definition);
+            }
             var existingMarker = marker == null ? null : assembly.CustomAttributes.FirstOrDefault(a => a.AttributeType.FullName == marker.FullName);
             if (existingMarker != null)
             {
@@ -140,14 +148,13 @@ public static class ShrinkAssemblyWeaver
         if (type.Fields.Any(field => field.Name == bindingFieldName))
             throw new InvalidOperationException($"Reserved generated field already exists on {type.FullName}: {bindingFieldName}.");
 
-        var disposableType = module.ImportReference(typeof(IDisposable));
+        var disposableType = new TypeReference("System", "IDisposable", module, module.TypeSystem.CoreLibrary);
         var bindingField = new FieldDefinition(bindingFieldName, FieldAttributes.Private, disposableType);
         type.Fields.Add(bindingField);
         var eventBusType = RequireType(module, "ShrinkEventBus.EventBus", EventRuntime);
         var attachMethod = ImportMethod(module, eventBusType,
             method => method.Name == "Attach" && method.IsStatic && method.Parameters.Count == 2);
-        var disposeMethod = module.ImportReference(typeof(IDisposable).GetMethod(nameof(IDisposable.Dispose))
-            ?? throw new InvalidOperationException("IDisposable.Dispose was not found."));
+        var disposeMethod = new MethodReference("Dispose", module.TypeSystem.Void, disposableType) { HasThis = true };
         InjectAwake(type, module, bindingField, attachMethod);
         InjectOnDestroy(type, module, bindingField, disposeMethod);
     }
@@ -638,10 +645,14 @@ public static class ShrinkAssemblyWeaver
         {
             var opcode = Convert.ToInt32(attribute.ConstructorArguments[0].Value);
             var route = attribute.ConstructorArguments.Count > 1 ? attribute.ConstructorArguments[1].Value as string ?? string.Empty : string.Empty;
-            var key = $"{opcode}:{route}";
-            if (seen.TryGetValue(key, out var previous))
-                throw new InvalidOperationException($"Duplicate network opcode/route {key}: {previous} and {type.FullName}.");
-            seen[key] = type.FullName;
+            Check("opcode:" + opcode);
+            if (!string.IsNullOrWhiteSpace(route)) Check("route:" + route.Trim());
+            void Check(string key)
+            {
+                if (seen.TryGetValue(key, out var previous))
+                    throw new InvalidOperationException($"SHRINK002 Duplicate {key}: {previous} and {type.FullName}. Assign unique opcodes and nonempty routes.");
+                seen[key] = type.FullName;
+            }
         }
     }