There doesn't appear to be any public API to do this. Searching GitHub, there are some codes that do this, but they are using non-public API (e.g. using CGSCopyManagedDisplaySpaces)

let window : NSWindow? = nil ... window?.collectionBehavior = .canJoinAllSpaces // window will be in all Spaces window?.collectionBehavior = .moveToActiveSpace // when window is activated, move to active Space window?.collectionBehavior = .stationary // Expose doesn't affect window, so it stays visible and stationary, like the Desktop window window?.collectionBehavior = .managed // window participates in Spaces and Expose (i.e. normal window). there are other options....

Thanks for your response. https://feedbackassistant.apple.com/feedback/9824294 By definition the bug only occurs occasionally. Gave a link to the code and the line to comment out to get the problem to appear. Unfortunately, there is no deterministic way to reproduce.

One clue is when the code starts, it always captures the Desktop background images correctly. It seems to fail only when the NSWorkspace.activeSpaceDidChangeNotification is sent. Introducing a block for 0.25 seconds seems to insure the image capture succeeds. Would prefer a better option than blocking.