Extension commands are not proxied between remote and workstation extension hosts

Per this documentation I expect messages to be proxied between remote and local extension hosts. https://code.visualstudio.com/api/advanced-topics/remote-extensions#communicating-between-extensions-using-commands

This is my setup.

Version: 1.74.1 (user setup)
Commit: 1ad8d514439d5077d2b0b7ee64d2ce82a9308e5a
Date: 2022-12-14T10:30:51.966Z
Electron: 19.1.8
Chromium: 102.0.5005.167
Node.js: 16.14.2
V8: 10.2.154.15-electron.0
OS: Windows_NT x64 10.0.22621
Sandboxed: No

And yes, I have tried using Insiders 1.75.0

I don't know whether this is SSH or all remoting. I only have SSH to test with.

Steps to Reproduce

1. Get the test samples
   • https://github.com/PeterWone/remote-client-for-sample-agent
   • https://github.com/PeterWone/sample-agent
2. Build a VSIX for sample-agent and install it
3. Build a VSIX for the test client.
4. Connect to a remote workspace then install the test client VSIX so as to get it onto the workspace extension host.

5. Test the command for local and remote workspaces.

Here it is working for a local workspace.

Here it is failing for a remote workspace ie when the command is invoked from a remote extension host.

Does this issue occur when you try this locally?: No obviously not
Does this issue occur when you try this locally and all extensions are disabled?: Yes but not finding the agent is hardly surprising if you don't allow it to run

For further information see https://stackoverflow.com/questions/74780962