Spec42 for VS Code
Spec42 is open, local-first tooling for SysML v2 and KerML: edit textual models with live feedback, understand structure and behavior beyond the source, and keep the same analysis engine in the editor, CI, and assistant workflows.
This extension is the primary modeling surface. Marketplace builds include the matching language server, standard library, and Elan8 domain libraries — install, open a .sysml or .kerml file, and start modeling.
Why Spec42 in the editor
Textual SysML v2 is only as useful as the feedback around it. Spec42 focuses on three things that matter while you work:
- Confidence while editing — diagnostics, navigation, and completion that stay with you as the model grows across files.
- Understanding beyond the source — Feature Inspector shows resolved semantics, not just tokens.
- Continuity outside the IDE — the same engine powers CLI checks, GitHub Actions, and assistant tools, so editor results and automation stay aligned.
Everything runs locally. Models stay in your workspace; Spec42 does not require a cloud modeling runtime.
What you get
- Live diagnostics, semantic highlighting, completion, hover, snippets, and formatting.
- Elan8 file icons for
.sysml and .kerml files in light and dark themes, unless your file
icon theme supplies its own matching icons.
- Import completion for definitions in other packages, including admitted libraries. Accepting
a suggestion inserts its reference and a private import together; the package path distinguishes
definitions with the same name.
- Add all unambiguous missing imports in Source Actions (
source.fixAll.spec42.imports).
It groups repeated references and leaves ambiguous or conflicting cases for individual fixes.
- Definitions, references, rename, document symbols, and hierarchy navigation.
- Workspace-aware indexing for multi-file models and configured libraries.
- Feature Inspector for resolved typing, inheritance, relationships, values, and keyword help.
- Bundled SysML standard library plus searchable Elan8 domain libraries.
- A persistent Views panel in the secondary side bar, backed by the native renderer.
Choose an authored view from namespace groups sorted alphabetically. The title bar offers
Fit View, Go to View Definition, and Export View…. The export menu offers SVG,
PNG, transparent-background variants, and Copy view JSON. The canvas follows the editor
theme; image exports use white by default. Views refresh as analysis completes, and unsupported
syntax has clickable diagnostic locations in the view details.
Spec42: Open Views focuses the panel.
- Built-in Copilot Language Model Tools for check, doctor, model export, and diagnostic explanation.
Views
| View |
What it is for |
| General View |
Structure and relationships across the exposed model. |
| Interconnection View |
Parts, ports, connectors, and architecture wiring. |
| Action Flow View |
Control and data flow through actions. |
| State Transition View |
States and transitions for lifecycle behavior. |
| Sequence View |
Lifelines and messages for interaction-oriented models. |
| Browser View |
Hierarchical membership browsing. |
| Grid View |
Tabular arrangement of exposed elements and relationships. |
| Geometry View |
Spatial items (partial while authored geometry and 3D catch up). |
Get started
- Install SysML v2 Editor from the Visual Studio Marketplace.
- Open a
.sysml or .kerml file — or pick the starred timer example from the Spec42 sidebar.
- Use navigation, diagnostics, Feature Inspector, and Open Views as you explore.
Full walkthrough: Getting Started.
For CLI checks, CI, environment diagnostics, and other AI hosts, see the main Spec42 README and the docs linked below. Editor and automation share the same analysis engine.
Learn more
Settings, advanced configuration, and contributor notes live in docs/ and the repository development guide rather than this Marketplace overview.
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