Preserve existing proto files instead of overwriting

If a proto file already exists (committed to repo), don't overwrite it
with a placeholder. This allows first-time builds to work correctly
when the proto file is already in the repository.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Svrnty.CQRS.Grpc.Generators/ProtoFileSourceGenerator.cs

@@ -65,7 +65,7 @@ public class ProtoFileSourceGenerator : IIncrementalGenerator
                     /// <summary>
                     /// Contains the auto-generated Protocol Buffer definition
                     /// </summary>
-                    internal static class GeneratedProtoFile
+                    public static class GeneratedProtoFile
                     {
                         public const string FileName = "{{protoFileName}}";
 

Svrnty.CQRS.Grpc.Generators/WriteProtoFileTask.cs

@@ -39,6 +39,16 @@ public class WriteProtoFileTask : Task
     [Required]
     public string ProtoFileName { get; set; } = string.Empty;
 
+    /// <summary>
+    /// The root namespace of the project (optional, falls back to AssemblyName)
+    /// </summary>
+    public string RootNamespace { get; set; } = string.Empty;
+
+    /// <summary>
+    /// The assembly name of the project (used for proto namespace if RootNamespace not set)
+    /// </summary>
+    public string AssemblyName { get; set; } = string.Empty;
+
     public override bool Execute()
     {
         try
@@ -57,6 +67,16 @@ public class WriteProtoFileTask : Task
                 "GeneratedProtoFile.g.cs"
             );
 
+            // Check if proto file already exists (committed to repo or from previous build)
+            var existingProtoPath = Path.Combine(ProjectDirectory, OutputDirectory, ProtoFileName);
+            if (File.Exists(existingProtoPath) && !File.Exists(generatedFilePath))
+            {
+                Log.LogMessage(MessageImportance.High,
+                    $"Svrnty.CQRS.Grpc: Using existing proto file at {existingProtoPath}. " +
+                    "To regenerate, delete the file and build twice.");
+                return true;
+            }
+
             if (!File.Exists(generatedFilePath))
             {
                 Log.LogWarning(
@@ -65,13 +85,30 @@ public class WriteProtoFileTask : Task
 
                 // Write a minimal placeholder proto file so Grpc.Tools doesn't fail
                 // The real content will be generated on the next build
-                var placeholderProto = @"syntax = ""proto3"";
+                // Use project's namespace so GrpcGenerator can find the service base types
+                var projectNamespace = !string.IsNullOrEmpty(RootNamespace) ? RootNamespace
+                    : !string.IsNullOrEmpty(AssemblyName) ? AssemblyName
+                    : "Generated";
+                var grpcNamespace = $"{projectNamespace}.Grpc";
 
-option csharp_namespace = ""Generated.Grpc"";
+                var placeholderProto = $@"syntax = ""proto3"";
+
+option csharp_namespace = ""{grpcNamespace}"";
 
 package cqrs;
 
-// Placeholder proto file - will be regenerated on next build
+// Placeholder proto file - will be regenerated on next build with actual services
+// Using namespace: {grpcNamespace}
+
+// Empty service definitions so Grpc.Tools generates base classes
+service CommandService {{
+}}
+
+service QueryService {{
+}}
+
+service DynamicQueryService {{
+}}
 ";
                 var placeholderOutputPath = Path.Combine(ProjectDirectory, OutputDirectory);
                 Directory.CreateDirectory(placeholderOutputPath);

Svrnty.CQRS.Grpc.Generators/build/Svrnty.CQRS.Grpc.Generators.targets

@@ -32,6 +32,8 @@
       ProjectDirectory="$(MSBuildProjectDirectory)"
       IntermediateOutputPath="$(IntermediateOutputPath)"
       OutputDirectory="$(ProtoOutputDirectory)"
-      ProtoFileName="$(GeneratedProtoFileName)" />
+      ProtoFileName="$(GeneratedProtoFileName)"
+      RootNamespace="$(RootNamespace)"
+      AssemblyName="$(AssemblyName)" />
   </Target>
 </Project>