Features

• 🎨 8 diagram kinds — overview / block definition (BDD) / internal block (IBD) / requirement / use case / state / activity / sequence
• ✏️ Edit straight from the diagram — move, resize, connect, rename and delete, all written back to the text (manual layout saved to a sidecar)
• 🔎 Language support — syntax highlighting, real-time diagnostics (syntactic + semantic), completion, outline, cross-file go-to-definition and hover
• 🔗 Two-way sync — click a diagram element ⇄ jump to source, editor cursor ⇄ highlight in the diagram
• 🤖 Claude (MCP) integration — analyze, validate and query the model as structure (Claude Code / Desktop / VS Code AI)
• 📦 Multi-file / remote ready (Remote-SSH / WSL / Dev Containers), 📚 bundled standard library + official OMG samples

Installation

Search for “SysML v2 Studio” in the VS Code Marketplace and install, or:

code --install-extension engineer-fumi.sysml-v2-studio

Requires VS Code 1.101 or later. To build a .vsix from source, see the development guide.

Quick start — preview a diagram

1. Open a .sysml / .kerml file (the bundled samples/ are the easiest start)
2. Click the diagram icon at the top-right of the editor, or run “SysML: Open Diagram” from the Command Palette → the diagram previews next to the editor
3. Switch between the 8 kinds via the selector at the top of the panel, or “SysML: Open Diagram by Kind”
4. Drag boxes to lay them out, right-click to connect / change line style / delete → changes are written back to the source text automatically (layout saved to .sysml-layout.json)

Click an element in the diagram to jump to the matching source line; the editor cursor position is highlighted back in the diagram.

Claude (MCP) integration

The extension bundles a standalone MCP server so AI like Claude can treat your .sysml model as structure rather than text — exposing tools for parsing, validation, requirement listing and diagram structure.

Depending on which client you use, do one of these two things.

① Using VS Code's AI (Copilot / agent) → nothing to configure

If you have this extension installed on VS Code 1.101 or later, there is nothing to do. The extension registers the MCP server automatically. Open “MCP: List Servers” from the Command Palette — if “SysML v2 Studio” is listed, it's active.

② Using Claude Code / Claude Desktop → one line to register

For Claude Code (a client separate from VS Code), run this once at your project root (npx, so no prior install needed):

claude mcp add sysml -- npx -y @engineer-fumi/sysml-v2-mcp "$(pwd)"

For Claude Desktop, add this to the config file:

{ "mcpServers": { "sysml": {
  "command": "npx",
  "args": ["-y", "@engineer-fumi/sysml-v2-mcp", "<absolute path to your model folder>"]
} } }

Tools provided: list_files / outline / validate / find_element / list_requirements / describe_diagram. For registration variants (explicit path, self-build), tool details and usage examples, see the Claude (MCP) integration guide.

Notation ↔ diagram

The same text model is rendered differently depending on the diagram kind you choose. Below is a minimal example for each kind and its actual rendered result (the hero overview image above is generated the same way).

Block definition diagram (BDD) — structure, composition, specialization of definitions

package Powertrain {
  part def Vehicle;
  part def Engine;
  part def Cylinder;
  part v : Vehicle { part engine : Engine; }
  part e : Engine { part cylinders : Cylinder[4]; }
}

Internal block diagram (IBD) — connections inside a part (port / connect)

package Hydraulics {
  port def FluidPort;
  part def Pump { port outlet : FluidPort; }
  part def Tank { port inlet : FluidPort; }
  part system {
    part pump : Pump;
    part tank : Tank;
    connect pump.outlet to tank.inlet;
  }
}

Requirement diagram — requirements and satisfy relations

package Requirements {
  requirement def MassLimit {
    doc /* 車両総質量は 1500 kg 以下であること */ // "Total vehicle mass shall be at most 1500 kg"
    attribute limit : Real = 1500.0;
  }
  requirement massReq : MassLimit;
  part vehicle;
  satisfy massReq by vehicle;
}

Use case diagram — use cases with actors and perform

package Robot {
  part def Operator;
  use case def Operate { subject robot : Robot; actor operator : Operator; }
  use case def Maintain { subject robot : Robot; actor operator : Operator; }
  use case operate : Operate;
  part operator : Operator { perform operate; }
}

State transition diagram — states and transitions (with triggers)

package Machine {
  state def BrewCycle {
    state off;
    state idle;
    state heating;
    state brewing;
    transition first off accept powerOn then idle;
    transition first idle accept startCmd then heating;
    transition first heating accept ready then brewing;
  }
}

Activity diagram — actions with succession / item flow

package Process {
  item def Order;
  action def Fulfill {
    action validate;
    action ship;
    first validate then ship;
    flow of Order from validate to ship;
  }
}

For diagram kinds, editing operations and layout persistence, see the diagram feature guide.

SysML v2 conformance

This extension implements a practical subset of the OMG SysML v2 textual notation (overview based on a code audit; for details and evidence see the conformance matrix).

The level definitions (Full / Partial / Parse-only / None) and the evidence for each area are documented in the conformance matrix.

Documentation

• Diagram features — diagram kinds, editing, layout persistence
• Supported notation & limitations — the SysML v2 subset supported
• Conformance matrix — detailed language area × level table
• Claude (MCP) integration guide — MCP server registration, tools, usage
• Development guide — architecture, build, test, publish

Documentation pages are currently written in Japanese.

License

MIT. The official OMG samples under samples/omg/ are EPL-2.0 (details). Bundled third-party components (React, etc.) are listed in THIRD-PARTY-NOTICES.txt.