Since version 3.16.0 of the LSP spec, a data field is available for diagnostics (source). This data field can be used to provide additional context for code actions. One useful example is a diagnostic/marker indicating a variable is undefined, and a code action providing a "Replace with ...", using this data to get the string to replace with.

However, the IMarker and IMarkerData interfaces currently don't have this field.

Steps:

• Add the data field to the monaco core (this repo): Expose data attribute to marker #279065
• Update the monaco-editor repo once this is done.