rvt-mcp CLAUDE.md

RvtMcp-MCP

Open-source (Apache-2.0) MCP gateway that lets Claude Code (and any MCP-capable client) drive Autodesk Revit 2022–2027.

Architecture

Full C# stack. No TypeScript. Single language, single build system. Multi-version: one plugin shell per Revit 2022–2027.

MCP client (Claude Code / Cursor / Cline / …) → stdio → C# MCP Server (.NET 8 Console App) → TCP or Named Pipe → per-version C# plugin shell → Revit 2022–2027 API

Two processes:

• RvtMcp.Server.exe — MCP Server, runs as separate process, stdio transport (ModelContextProtocol NuGet)
• RvtMcp.Plugin.dll — Revit addin, loads inside Revit.exe, TCP listener (R22–R24) or Named Pipe (R25–R27) + ExternalEvent marshalling. Each Revit version gets its own shell DLL compiled from the same src/shared/ source glob.

Communication: newline-delimited JSON (NDJSON). Discovery files written per Revit version in %LOCALAPPDATA%\RvtMcp\:

• revit-2022.json / revit-2023.json / revit-2024.json — TCP transport (port OS-assigned) + auth token + PID
• revit-2025.json / revit-2026.json / revit-2027.json — Named Pipe transport + auth token + PID

Discovery file format (schema_version=2):

{
  "schema_version": 2,
  "revit_year": 2024,
  "transport": "tcp",
  "port": 49891,
  "pipe_name": null,
  "auth_token": "...",
  "pid": 67890
}

Server auto-detects which Revit is running by scanning these files (skipping any whose pid is dead). Use --target 2022 etc. (4-digit calendar year, NOT legacy R-codes) to pin a specific version when multiple Revits run. Agents should call revit_list_available_targets to enumerate live instances and revit_get_current_target to inspect the pinned target rather than guessing version strings — revit_switch_target hard-fails with an educational error if passed an R-code like R24.

Project Structure

src/
├── RvtMcp.sln         # Solution (Server + 6 plugin shells)
│
├── server/                   # MCP Server (Console App, .NET 8)
│   ├── RvtMcp.Server.csproj
│   └── Program.cs            # MCP tools + transport client to plugin shells
│
├── shared/                   # Source shared by all plugin shells (glob-included)
│   ├── Handlers/             # One file per command (send_code, create_grid, batch_execute, …)
│   ├── Commands/             # Ribbon button commands
│   ├── Config/               # Configuration loaders
│   ├── Infrastructure/       # CommandDispatcher, McpEventHandler, ResponseSizeGuard, …
│   ├── Transport/            # TcpTransportServer, PipeTransportServer, ITransportServer
│   ├── Logging/              # McpLogger
│   ├── Security/             # AuthToken, SecretMasker
│   ├── ToolBaker/            # Self-evolution engine (list_baked_tools, run_baked_tool, adaptive suggestions)
│   └── Views/                # HistoryWindow
│
├── plugin-r22/               # Revit 2022 shell (.NET 4.8, TCP)
├── plugin-r23/               # Revit 2023 shell (.NET 4.8, TCP)
├── plugin-r24/               # Revit 2024 shell (.NET 4.8, TCP)
├── plugin-r25/               # Revit 2025 shell (.NET 8, Named Pipe)
├── plugin-r26/               # Revit 2026 shell (.NET 8, Named Pipe)
└── plugin-r27/               # Revit 2027 shell (.NET 10, Named Pipe)