[xen2]

Game Studio 4.4 is built for .NET 10. Until now, a game had to target the same .NET version as the editor: move your game to .NET 11, and Game Studio could not load it anymore.

With this PR, you can move your game to .NET 11 (or any later version) and keep using the same Game Studio. When a project needs a newer .NET, Game Studio restarts itself on it. The asset compiler does the same during dotnet build.

Related issues

• Fixes Target .NET STS Versions #2696: games can use a .NET STS release such as .NET 11 without Stride itself moving to it.
• Fixes the second part of Unable to build project with latest Visual Studio #2523: the asset compiler no longer runs on an older .NET than the game and silently skips assets, so the DOTNET_ROLL_FORWARD=LatestMajor workaround is not needed anymore. The first part (the MSBuild lookup when the editor's runtime has no matching SDK installed) is unchanged.
• See also fix: Prepare ThreadPool for .Net11+ #3351, which prepared the engine's thread pool for .NET 11.

What you can do

Move your game to .NET 11

1. Install the .NET 11 SDK.
2. Change <TargetFramework> in your game projects to net11.0.
3. Open the project in Game Studio, as usual.

Game Studio notices that the project needs .NET 11 and restarts on it. The window title shows the .NET version it runs on, together with the graphics API:

Opening another project later (File > Open, File > New) switches back and forth between .NET 10 and .NET 11 as each project needs. dotnet build of the game runs the asset compiler on .NET 11 too.

Get a clear message when .NET is missing

If the project needs a .NET version that is not installed, Game Studio tells you what is missing and where to get it, then returns to the project selection window:

Try Game Studio on a newer .NET from the launcher

When a newer .NET is installed, the launcher shows a runtime selector below the version. The default is the editor's own .NET, and each newer version is offered as a minimum:

• .NET 10 or newer (default): Game Studio runs on .NET 10, or on what the project needs.
• .NET 11 or newer: Game Studio runs on .NET 11 even for a .NET 10 project, for example to try your project on .NET 11 before moving it.

A project that needs a newer version always gets it. The selector only appears for Stride versions that support it, so older versions work as before. With only one .NET installed, it stays hidden.

Note: it's the same selector we had a long time ago when we had both .NET Framework and .NET Core side by side.

Same from the command line

stride studio                         # restarts on the .NET version the project needs
stride studio --framework net11.0     # at least .NET 11

Start with only a newer .NET installed

Game Studio, the launcher, the CLI and the asset compiler now start even when .NET 10 is not installed, as long as a newer version is. When .NET 10 is installed, they keep using it.

How it works

Choosing the .NET version

DotNetHostSelector (in sources/shared/Stride.NuGetResolver, used by Game Studio, the launcher and the CLI) picks the .NET major from:

Input	Rule
The session's executable projects	First TargetFramework(s) entry, from obj/project.assets.json or the csproj. A minimum.
--framework net11.0 or STRIDE_RUNTIME_MAJOR (launcher choice, CLI)	Also a minimum: it can raise the project's major, never lower it.
global.json SDK pin	Exact, and wins over both (MSBuild runs inside the editor and must use that SDK).

The editor never runs below its own major. When a newer major is needed, the selector writes the editor's runtimeconfig re-pointed at that major under %LOCALAPPDATA%\stride\host and restarts through dotnet exec --runtimeconfig <file> ... --host-relaunched.

Game Studio

• The check runs at startup and on every restart path (project selection, File > Open, File > New, reload, restart after a partial load), all through one restart helper that replays the original arguments.
• A restarted editor is a dotnet.exe process. It gets a per-install taskbar identity and the Stride icon, so it does not show as ".NET Host", and no console window opens.

Asset compiler

• The package ships Stride.AssetCompiler.runtimeconfig.template.json, written at build time by the SDK's own GenerateRuntimeConfigurationFiles task with every framework at {MAJOR}.0.0-0 and LatestMinor, so previews and releases of a major are both found.
• Stride.AssetCompiler.targets compares the project's major with the compiler's. When the project's is newer, it fills {MAJOR} with one literal Replace, writes the file under obj/, and runs the compiler through dotnet exec --runtimeconfig. No JSON editing in MSBuild, no environment variable.
• Compiler slave processes start on the same runtime as their parent.

Tools

RollForward=Major on Game Studio, the launcher, the CLI and the asset compiler.

Launcher and CLI

• The runtime selector is shown only for editors that understand the choice, detected by a type-reference scan of the editor assembly, so older Stride versions never receive the new arguments. Its strings are localized.
• Uninstalling a version detects a running editor, including one restarted through dotnet exec, through a per-install named mutex.
• stride studio --framework is dropped for older editors. stride new and stride upgrade run the asset compiler on the session's major.

Also in this PR

• Launcher: legacy target framework selector removed. It only mattered for Stride 4.0.1 (.NET Framework 4.7.2 or .NET 5 editor), and it was already broken: the launcher ignored the choice and always started the 4.7.2 editor. Not worth fixing for such an old release.
• Launcher: recent projects open with the exact Stride version they reference when that version is installed (useful for dev builds), else with the installed version of the same major.minor, as before.
• Launcher: uninstall fix. The package store now waits for the "still running" check before deleting files, and the dialog is shown on the UI thread. Before, the check did not block the deletion, and when it found a running process the launcher crashed.

Testing

• Unit tests: 35 selector tests in Stride.Launcher.Tests (decision table, first-target-framework rule, global.json pin, explicit choice as a minimum, missing runtime and SDK messages, runtimeconfig rewrite, editor capability scan).
• Manual, Windows, .NET 10 and .NET 11 RC 1: the scenarios above, from a local dev build and from an installed package, plus uninstall refused while a restarted editor is open, and stride studio with an older editor (beta6). Starting with only a newer .NET installed was checked with a small app using the same RollForward=Major setting, not with Game Studio itself.
• Not tested: Linux, the asset compiler targets under Visual Studio's msbuild.exe, and the compiler slave path (no production command starts slaves today).

Known limitations

• Game Studio runs on a newer .NET than it was built for when the project asks for it. This is the user's choice, so there is no "untested runtime" warning.
• For a multi-targeting game, the first target framework decides, on every platform. This matches how the editor already picks the project to load.