MEAI chat web template with --aspire flag: Class name mismatch in AppHost Program.cs causes build error

[ViveliDuCh]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When using dotnet new aichatweb --provider [azureopenai,openai,ollama,githubmodels] --aspire -o my.aichatweb.project, if the project name or a related template class contains a dot (e.g. some.name), the generator creates a normalized class name with underscores (some_name) in the Projects namespace. However, in the generated Program.cs within the AppHost project, the original (non-normalized) name (some.name) is used in:

var webApp = builder.AddProject<Projects.some.name>("aichatweb-app");

This causes a build error because Projects.some.name does not exist, only Projects.some_name does. The issue appears with any of the providers and requires manual editing of Program.cs to use the normalized name. This should be handled automatically by the template or generator logic.

Expected Behavior

The generated Program.cs should use the normalized class name, e.g. Projects.some_name, to match the generated class and avoid build errors.

Steps To Reproduce

1. Run dotnet new aichatweb --provider openai --aspire -o my.aichatweb.project
2. Use a project name or template parameter that contains a dot (e.g. some.name)
3. Configure the AI Model Provider
4. Try to build the solution
5. Observe the CS0234 build error referencing a missing type or namespace name some.name in the namespace 'Projects'
6. Manually change to Projects.some_name in some.name.AppHost/Program.cs to fix the build

Exceptions (if any)

Build error: error CS0234: The type or namespace name 'some' does not exist in the namespace 'Projects' (are you missing an assembly reference?)

.NET Version info

dotnet --info
.NET SDK:
 Version:           9.0.304
 Commit:            f12f5f689e
 Workload version:  9.0.300-manifests.75243b89
 MSBuild version:   17.14.16+5d8159c5f

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.26100
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\9.0.304\

Anything else?

• .NET Aspire version: 9.4.0-preview.1.25378.8
• The IDE: VS/VS Code
• This issue occurs with all listed providers: azureopenai, openai, ollama, githubmodels
• The issue is not reported in the issue tracker as of this writing.

Side note:

There is a related issue with template-generated class and namespace normalization when project or folder names contain characters not allowed in C# identifiers (such as #). While the code generator correctly normalizes these names (e.g., converting on#ly to on_ly) for type and namespace declarations, it fails to apply the same normalization in all code references—such as those in Web/Program.cs. This inconsistency causes build errors due to mismatched identifiers and requires manual intervention to resolve. For robust code generation, identifier normalization should be applied consistently across all generated files and references.

[jeffhandley]

To fix this, we would need our template logic to replace the class name using the same logic as Aspire's code generator with the (((?<=\.)|^)(?=\d)|\W) regex defined here:

https://github.com/dotnet/aspire/blob/5be4f73b7dfb0d1665d73bd96434295e268a0453/src/Aspire.Hosting.AppHost/build/Aspire.Hosting.AppHost.in.targets#L8

Our template can define another replacer similar to what was done in this PR:
Generate the vector store index name using project name. Fix symbol handling for CSS and dimensions. (dotnet/extensions#6025)