WireViz0.4.0 or later; which requires Python 3.7 or later, and the Graphviz binaries (through the installer, not pip)
Running
Open a WireViz YAML file.
Use the WireViz: Preview button on the editor toolbar (right of tabs),
or using the default F8 shortcut key.
Once the preview is open, it will refresh every time you save the file.
This behaviour can be disabled by setting "wireviz.refreshPreviewOnSave": false.
Configuration
Open VSCode settings, filter for WireViz. You'll find settings for command-line args to specify, and a couple extension-specific settings.
Troubleshooting
Please make sure you're running WireViz 0.4 or above. Their new command line options are incompatible with 0.3 and below.
Errors will result in a pop-up message. The full message (if available) should also be shown in the Output window. In the event that the output window doesn't show automatically, please select View > Output, and select WireViz Preview in the dropdown.