How to create new layer at top of stack

OK, with further testing there appears to be a fundamental difference in how ExtendScript DOM scripting adds a new layer vs. regular Photoshop use...

All one needs to do is use:

app.activeDocument.artLayers.add();

And the new layer will always be created at the top of the stack, regardless of whether an expanded layer group is at the top of the stack or not.

I believe that this is what @r-bin may have been hinting at! :]

@Conrad_C @r-bin @Stephen Marsh  Thanks all.

Select all layers in the target document. If the new layer is duplicated from a separate source document, then it does go to the top of the layer stack, even if there is an expanded/open layer group at the top of the stack!

I can't think of one offhand, but there are shortcuts to create a new layer and move it to the top of the stack (depending on layer structure, groups may get the way) - this can be recorded into an action for F-key shortcut playback:

Cmd/Ctrl + Opt/Alt + Shift + N
Cmd/Ctrl + Shift + ]

Otherwise, a script would offer more precise control and can be made into a custom keyboard shortcut or recorded as an action for an F-key shortcut.

EDIT: I see that @Conrad_C replied with some great options while I was typing!

I’m not sure if there is a direct shortcut. But there are some indirect ways based on how layer selection affects where a new layer appears.

If a layer is selected in the Layers panel, a new layer is created above it.

If no layers are selected in the Layers panel, a new layer is created at the top of the layer stack.

Knowing that, you could get there using a workaround with the mouse, a menu, or two keyboard shortcuts.

• Mouse method: Make sure the Layers panel is tall enough to show an empty area under the layer stack, so you can click there to deselect all layers. 
• Menu method: Choose Select > Deselect All Layers.  
• Keyboard method: The default set of Photoshop keyboard shortcuts does not define a shortcut for Deselect All Layers, but you can add your own by choosing Edit > Keyboard Shortcuts. (That’s what I did.) After you set that up, press your shortcut for the Deselect All Layers command. Now you can press the shortcut for Deselect All Layers followed by the shortcut for Layer > New > Layer. 

After you use any method to deselect all layers, the next layer you create will be at the top of the layer stack.

If you wanted to get it down to one step, use the Actions panel to create an action that combines the two commands. Add an action step that applies the command Select > Deselect All Layers, and another step that applies the command Layer > New > Layer. After you set that up, you can run the action either with the mouse, or by assigning a function key shortcut to the action.