fix(generators): Resolve duplicate type definitions in MessageJsonContext

.github/dependabot.yml

@@ -6,7 +6,9 @@ updates:
     target-branch: "develop"
     schedule:
       interval: "weekly"
-      day: "monday"
+      day: "friday"
+      time: "17:00"
+      timezone: "America/New_York"
     open-pull-requests-limit: 10
     assignees:
       - "philcarbone"
@@ -24,7 +26,9 @@ updates:
     target-branch: "develop"
     schedule:
       interval: "weekly"
-      day: "monday"
+      day: "friday"
+      time: "17:00"
+      timezone: "America/New_York"
     open-pull-requests-limit: 5
     assignees:
       - "philcarbone"

src/Whizbang.Generators/JsonMessageTypeInfo.cs

@@ -20,7 +20,16 @@ internal sealed record JsonMessageTypeInfo(
     bool IsSerializable,
     PropertyInfo[] Properties,
     bool HasParameterizedConstructor
-);
+) {
+  /// <summary>
+  /// Unique identifier derived from fully qualified name, suitable for C# identifiers.
+  /// Strips "global::" prefix and replaces "." with "_".
+  /// E.g., "global::MyApp.Commands.StartCommand" becomes "MyApp_Commands_StartCommand".
+  /// This prevents duplicate field/method names when types have the same SimpleName.
+  /// </summary>
+  /// <tests>tests/Whizbang.Generators.Tests/MessageJsonContextGeneratorTests.cs:Generator_WithSameSimpleNameInDifferentNamespaces_GeneratesUniqueIdentifiersAsync</tests>
+  public string UniqueIdentifier => FullyQualifiedName.Replace("global::", "").Replace(".", "_");
+}
 
 /// <summary>
 /// Information about a property for JSON serialization.

src/Whizbang.Generators/ListTypeInfo.cs

@@ -15,4 +15,13 @@ public sealed record ListTypeInfo(
     string ListTypeName,
     string ElementTypeName,
     string ElementSimpleName
-);
+) {
+  /// <summary>
+  /// Unique identifier derived from element type name, suitable for C# identifiers.
+  /// Strips "global::" prefix and replaces "." with "_".
+  /// E.g., "global::MyApp.Models.OrderLineItem" becomes "MyApp_Models_OrderLineItem".
+  /// This prevents duplicate field/method names when element types have the same SimpleName.
+  /// </summary>
+  /// <tests>tests/Whizbang.Generators.Tests/MessageJsonContextGeneratorTests.cs:Generator_WithSameSimpleNameInDifferentNamespaces_GeneratesUniqueIdentifiersAsync</tests>
+  public string ElementUniqueIdentifier => ElementTypeName.Replace("global::", "").Replace(".", "_");
+}

src/Whizbang.Generators/MessageJsonContextGenerator.cs

@@ -50,7 +50,7 @@ public class MessageJsonContextGenerator : IIncrementalGenerator {
   private const string PLACEHOLDER_MESSAGE_ID = "MessageId";
   private const string PLACEHOLDER_FULLY_QUALIFIED_NAME = "__FULLY_QUALIFIED_NAME__";
   private const string PLACEHOLDER_SIMPLE_NAME = "__SIMPLE_NAME__";
-  private const string PLACEHOLDER_SAFE_NAME = "__SAFE_NAME__";
+  private const string PLACEHOLDER_UNIQUE_IDENTIFIER = "__UNIQUE_IDENTIFIER__";
   private const string PLACEHOLDER_GLOBAL = "global::";
   private const string PLACEHOLDER_INDEX = "__INDEX__";
   private const string PLACEHOLDER_PROPERTY_TYPE = "__PROPERTY_TYPE__";
@@ -395,7 +395,7 @@ private static string _generateLazyFields(Assembly assembly, ImmutableArray<Json
     foreach (var type in allTypes) {
       var field = messageFieldSnippet
           .Replace(PLACEHOLDER_FULLY_QUALIFIED_NAME, type.FullyQualifiedName)
-          .Replace(PLACEHOLDER_SAFE_NAME, _toSafeMethodName(type.FullyQualifiedName));
+          .Replace(PLACEHOLDER_UNIQUE_IDENTIFIER, type.UniqueIdentifier);
       sb.AppendLine(field);
     }
     sb.AppendLine();
@@ -404,7 +404,7 @@ private static string _generateLazyFields(Assembly assembly, ImmutableArray<Json
     foreach (var type in allTypes.Where(t => t.IsCommand || t.IsEvent)) {
       var field = envelopeFieldSnippet
           .Replace(PLACEHOLDER_FULLY_QUALIFIED_NAME, type.FullyQualifiedName)
-          .Replace(PLACEHOLDER_SAFE_NAME, _toSafeMethodName(type.FullyQualifiedName));
+          .Replace(PLACEHOLDER_UNIQUE_IDENTIFIER, type.UniqueIdentifier);
       sb.AppendLine(field);
     }
 
@@ -466,7 +466,7 @@ private static string _generateGetTypeInfo(Assembly assembly, ImmutableArray<Jso
     foreach (var type in allTypes) {
       var check = messageCheckSnippet
           .Replace(PLACEHOLDER_FULLY_QUALIFIED_NAME, type.FullyQualifiedName)
-          .Replace(PLACEHOLDER_SAFE_NAME, _toSafeMethodName(type.FullyQualifiedName));
+          .Replace(PLACEHOLDER_UNIQUE_IDENTIFIER, type.UniqueIdentifier);
       sb.AppendLine(check);
       sb.AppendLine();
     }
@@ -476,7 +476,7 @@ private static string _generateGetTypeInfo(Assembly assembly, ImmutableArray<Jso
     foreach (var type in allTypes.Where(t => t.IsCommand || t.IsEvent)) {
       var check = envelopeCheckSnippet
           .Replace(PLACEHOLDER_FULLY_QUALIFIED_NAME, type.FullyQualifiedName)
-          .Replace(PLACEHOLDER_SAFE_NAME, _toSafeMethodName(type.FullyQualifiedName));
+          .Replace(PLACEHOLDER_UNIQUE_IDENTIFIER, type.UniqueIdentifier);
       sb.AppendLine(check);
       sb.AppendLine();
     }
@@ -487,7 +487,7 @@ private static string _generateGetTypeInfo(Assembly assembly, ImmutableArray<Jso
       foreach (var listType in listTypes) {
         var check = listCheckSnippet
             .Replace("__ELEMENT_TYPE__", listType.ElementTypeName)
-            .Replace("__ELEMENT_SAFE_NAME__", _toSafeMethodName(listType.ElementTypeName));
+            .Replace("__ELEMENT_UNIQUE_IDENTIFIER__", listType.ElementUniqueIdentifier);
         sb.AppendLine(check);
         sb.AppendLine();
       }
@@ -612,8 +612,7 @@ private static string _generateMessageTypeFactories(Assembly assembly, Immutable
         "PARAMETER_INFO_VALUES");
 
     foreach (var message in messages) {
-      var safeName = _toSafeMethodName(message.FullyQualifiedName);
-      sb.AppendLine($"private JsonTypeInfo<{message.FullyQualifiedName}> Create_{safeName}(JsonSerializerOptions options) {{");
+      sb.AppendLine($"private JsonTypeInfo<{message.FullyQualifiedName}> Create_{message.UniqueIdentifier}(JsonSerializerOptions options) {{");
 
       // Generate properties array
       sb.AppendLine($"  var properties = new JsonPropertyInfo[{message.Properties.Length}];");
@@ -724,8 +723,7 @@ private static string _generateMessageEnvelopeFactories(Assembly assembly, Immut
         "PARAMETER_INFO_VALUES");
 
     foreach (var message in messages) {
-      var safeName = _toSafeMethodName(message.FullyQualifiedName);
-      sb.AppendLine($"private JsonTypeInfo<MessageEnvelope<{message.FullyQualifiedName}>> CreateMessageEnvelope_{safeName}(JsonSerializerOptions options) {{");
+      sb.AppendLine($"private JsonTypeInfo<MessageEnvelope<{message.FullyQualifiedName}>> CreateMessageEnvelope_{message.UniqueIdentifier}(JsonSerializerOptions options) {{");
 
       // Generate properties array for MessageEnvelope<T> (MessageId, Payload, Hops)
       sb.AppendLine("  var properties = new JsonPropertyInfo[3];");
@@ -1037,7 +1035,7 @@ private static string _generateListLazyFields(Assembly assembly, ImmutableArray<
     foreach (var listType in listTypes) {
       var field = snippet
           .Replace("__ELEMENT_TYPE__", listType.ElementTypeName)
-          .Replace("__ELEMENT_SAFE_NAME__", _toSafeMethodName(listType.ElementTypeName));
+          .Replace("__ELEMENT_UNIQUE_IDENTIFIER__", listType.ElementUniqueIdentifier);
       sb.AppendLine(field);
     }
 
@@ -1063,7 +1061,7 @@ private static string _generateListFactories(Assembly assembly, ImmutableArray<L
     foreach (var listType in listTypes) {
       var factory = snippet
           .Replace("__ELEMENT_TYPE__", listType.ElementTypeName)
-          .Replace("__ELEMENT_SAFE_NAME__", _toSafeMethodName(listType.ElementTypeName));
+          .Replace("__ELEMENT_UNIQUE_IDENTIFIER__", listType.ElementUniqueIdentifier);
       sb.AppendLine(factory);
       sb.AppendLine();
     }

src/Whizbang.Generators/Templates/Snippets/JsonContextSnippets.cs

@@ -19,11 +19,11 @@ internal class JsonContextSnippets {
   #endregion
 
   #region LAZY_FIELD_MESSAGE
-  private JsonTypeInfo<__FULLY_QUALIFIED_NAME__>? ___SAFE_NAME__;
+  private JsonTypeInfo<__FULLY_QUALIFIED_NAME__>? ___UNIQUE_IDENTIFIER__;
   #endregion
 
   #region LAZY_FIELD_MESSAGE_ENVELOPE
-  private JsonTypeInfo<MessageEnvelope<__FULLY_QUALIFIED_NAME__>>? _MessageEnvelope___SAFE_NAME__;
+  private JsonTypeInfo<MessageEnvelope<__FULLY_QUALIFIED_NAME__>>? _MessageEnvelope___UNIQUE_IDENTIFIER__;
   #endregion
 
   #region GET_TYPE_INFO_VALUE_OBJECT
@@ -32,13 +32,13 @@ internal class JsonContextSnippets {
 
   #region GET_TYPE_INFO_MESSAGE
 if (type == typeof(__FULLY_QUALIFIED_NAME__)) {
-  return Create___SAFE_NAME__(options);
+  return Create___UNIQUE_IDENTIFIER__(options);
 }
   #endregion
 
   #region GET_TYPE_INFO_MESSAGE_ENVELOPE
 if (type == typeof(MessageEnvelope<__FULLY_QUALIFIED_NAME__>)) {
-  return CreateMessageEnvelope___SAFE_NAME__(options);
+  return CreateMessageEnvelope___UNIQUE_IDENTIFIER__(options);
 }
   #endregion
 
@@ -52,17 +52,17 @@ internal class JsonContextSnippets {
 #endregion
 
 #region LAZY_FIELD_LIST
-private JsonTypeInfo<global::System.Collections.Generic.List<__ELEMENT_TYPE__>>? _List___ELEMENT_SAFE_NAME__;
+private JsonTypeInfo<global::System.Collections.Generic.List<__ELEMENT_TYPE__>>? _List___ELEMENT_UNIQUE_IDENTIFIER__;
 #endregion
 
 #region GET_TYPE_INFO_LIST
 if (type == typeof(global::System.Collections.Generic.List<__ELEMENT_TYPE__>)) {
-  return CreateList___ELEMENT_SAFE_NAME__(options);
+  return CreateList___ELEMENT_UNIQUE_IDENTIFIER__(options);
 }
 #endregion
 
 #region LIST_TYPE_FACTORY
-private JsonTypeInfo<global::System.Collections.Generic.List<__ELEMENT_TYPE__>> CreateList___ELEMENT_SAFE_NAME__(JsonSerializerOptions options) {
+private JsonTypeInfo<global::System.Collections.Generic.List<__ELEMENT_TYPE__>> CreateList___ELEMENT_UNIQUE_IDENTIFIER__(JsonSerializerOptions options) {
   var elementInfo = GetOrCreateTypeInfo<__ELEMENT_TYPE__>(options);
   var collectionInfo = new JsonCollectionInfoValues<global::System.Collections.Generic.List<__ELEMENT_TYPE__>> {
     ObjectCreator = static () => new global::System.Collections.Generic.List<__ELEMENT_TYPE__>(),

tests/Whizbang.Generators.Tests/MessageJsonContextGeneratorTests.cs

@@ -155,7 +155,7 @@ public record CreateOrder(string OrderId) : ICommand;
     await Assert.That(code).IsNotNull();
 
     // Should generate specific factory method for MessageEnvelope<CreateOrder>
-    // Safe names use fully qualified path to avoid collisions (e.g., MyApp_Commands_CreateOrder)
+    // Uses unique identifier from fully qualified name: MyApp.Commands.CreateOrder -> MyApp_Commands_CreateOrder
     await Assert.That(code!).Contains("CreateMessageEnvelope_MyApp_Commands_CreateOrder");
     await Assert.That(code).Contains("MessageEnvelope<global::MyApp.Commands.CreateOrder>");
   }
@@ -613,7 +613,51 @@ public record CreateOrder(string OrderId, List<PublicDetail> PublicItems) : ICom
     await Assert.That(code).IsNotNull();
     await Assert.That(code!).Contains("CreateOrder");
     await Assert.That(code).Contains("PublicDetail");
-    // PublicDetail should have factory method with safe name (namespace-qualified)
+    // PublicDetail should have factory method (uses unique identifier from FQN)
     await Assert.That(code).Contains("Create_MyApp_PublicDetail");
   }
+
+  [Test]
+  [RequiresAssemblyFiles()]
+  public async Task Generator_WithSameSimpleNameInDifferentNamespaces_GeneratesUniqueIdentifiersAsync() {
+    // Arrange - Two types with same SimpleName but different namespaces
+    // This would previously cause duplicate field names (_StartCommand) and factory methods
+    var source = """
+using Whizbang.Core;
+
+namespace MyApp.Commands {
+  public record StartCommand(string Data) : ICommand;
+}
+
+namespace MyApp.Events {
+  public record StartCommand(string Data) : IEvent;
+}
+""";
+
+    // Act
+    var result = GeneratorTestHelper.RunGenerator<MessageJsonContextGenerator>(source);
+
+    // Assert - Should not have compilation errors (duplicate identifiers would cause errors)
+    await Assert.That(result.Diagnostics).DoesNotContain(d => d.Severity == DiagnosticSeverity.Error);
+
+    var code = GeneratorTestHelper.GetGeneratedSource(result, "MessageJsonContext.g.cs");
+    await Assert.That(code).IsNotNull();
+
+    // Both types should be present with fully qualified names
+    await Assert.That(code!).Contains("global::MyApp.Commands.StartCommand");
+    await Assert.That(code).Contains("global::MyApp.Events.StartCommand");
+
+    // Should have unique field names (not duplicate _StartCommand)
+    // Uses namespace-qualified identifiers like _MyApp_Commands_StartCommand
+    await Assert.That(code).Contains("_MyApp_Commands_StartCommand");
+    await Assert.That(code).Contains("_MyApp_Events_StartCommand");
+
+    // Should have unique factory method names
+    await Assert.That(code).Contains("Create_MyApp_Commands_StartCommand");
+    await Assert.That(code).Contains("Create_MyApp_Events_StartCommand");
+
+    // Should have unique MessageEnvelope factory method names
+    await Assert.That(code).Contains("CreateMessageEnvelope_MyApp_Commands_StartCommand");
+    await Assert.That(code).Contains("CreateMessageEnvelope_MyApp_Events_StartCommand");
+  }
 }