The Notebook Concat Text Document api is not currently on track for finalization. Instead of having this functionality as part of VS Code core, we believe that individual extensions/languages are better equipped to build their own virtual document model of notebooks (in cases where such a model makes sense)

We plan to remove this proposed API once all current consumers have migrated off of it. The only known consumers today are:

• Jupyter @DonJayamanne
• Dot Net Interactive @brettfo, @colombod Migrate off of the concat text document API proposal dotnet/interactive#1966

Please let me know if you are still consuming this API and if there are any blockers that would prevent migrating off of it