Getting VS Code to allow unstable API's (KV in particular.)

[skybrian]

I'm using VS Code to write command-line tools that use KV, which is currently an unstable API.

For these files, the only way I know to get VS Code to type-check unstable API's is to add this to the top of each file:

   /// <reference lib="deno.unstable"/>

Supposedly, setting vscode.unstable to true in .vscode/settings.json should do it, but I've never been able to get it to work.
Specifically, it has no effect on command line tools (which I put in a commands subdirectory). Looks like it works for libraries (which I put in a lib/ subdirectory).

Has anyone else seen this work? Some kind of bug?