.NET Assembly
.NET assembly execution is for compiled add-ins and commands.
Scripts, MCP toolsets, and compiled commands each load in isolated assembly contexts: Revit 2025+ uses a collectible AssemblyLoadContext; Revit 2022–2024 on .NET Framework uses net48 scoped resolve.
Use it when you are developing a compiled command and want to run it from RevitDevTool during iteration.
In Revit, this fills the same practical role as Revit Add-In Manager: build a command assembly, load it, and run commands without packaging a full add-in workflow each time. For many development workflows, RevitDevTool can replace Add-In Manager while also giving you the surrounding logging, scripting, visualization, and tool workflow.
Running the Assembly
In Revit, assembly execution is centered around Revit command contracts such as IExternalCommand. In other hosts, the same idea applies to that host's command/tool assembly model.
Typical workflow:
- Build a command assembly.
- Add its folder to RevitDevTool settings.
- Let the command tree discover the assembly.
- Run the command from the panel or command browser.
Debugging
Attach a .NET debugger to the running host process (Revit.exe, acad.exe, …), set breakpoints in your compiled source, then run the command from RevitDevTool.
| IDE | Workflow |
|---|---|
| Visual Studio | Debug → Attach to Process → select host → Run command |
| VS Code | C# Dev Kit → Attach to Process → select host → Run command |
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For shared attach guidance (including C# and F# scripts), see Attach Debugger.
Version Notes
| Autodesk version | Runtime behavior |
|---|---|
| 2022-2024 | .NET Framework / net48; no unloadable AssemblyLoadContext |
| 2025-2026 | .NET 8; unloadable AssemblyLoadContext can be used |
| 2027 | .NET 10; follows modern .NET path |
The legacy .NET Framework path needs extra care around assembly loading and unmanaged DLL resolution.
Samples
Current samples:
samples/CSharpDemo/
samples/AcadCSharpDemo/
samples/McpToolsetDemo/
samples/RevitMcpToolSet/
User Guidance
When building external assemblies:
- target the correct Autodesk year/runtime;
- keep host API references aligned with the target year;
- test against the actual host when command behavior depends on host API context.
For build commands, see Build From Source.