I've seen Houdini use two different locations for a user directory:

• $HOME/houdini18.0
  
• $HOME/Documents/houdini18.0
  

How does Houdini decide which location to use?

I think you have to edit “C:\Users\%username%\…\Sidefx\houdini18.0\houdini.env”
Check if there is such a line , if not, add it, and edit it, such as :
HOME = “C:\Users\yourpath\Sidefx”

This ended up being related to how HOME was being handled by two tools I was using to develop with.

This may be worth articulating for others:
The Windows HOMEvariable dictates where Houdini will set HOUDINI_USER_DIR.

Some applications set a HOMEvariable explicitly, so Houdini produces a different HOUDINI_USER_DIRresolution when loading from that environment.

Since some of us use applications like Cmder or VS Code, which *add* a HOMEvariable to the windows default environment, Houdini's default launcher will also set HOUDINI_USER_DIRto that location. Not ideal, if you're making a Houdini plugin.

To summarize: Houdini will determine HOUDINI_USER_DIRbased on HOME.. To find out where that goes, type set HOMEin a windows terminal you plan to launch from.

@SideFX: From a tool authoring perspective, this behavior seems fragile; maybe it's worth creating another environment variable which stabilizes the location?

Omer