How can I capture "Align To" into an action?

Canvas should be equal ot same as Select > All. If you select all it is safe to align. Even if they change something in development selection will always match canvas and you won't have problem.

@musekic 

You're welcome!

There is a misunderstanding.

The "clue" is in the name of the script:

Align Active Layer to Select All.jsx

The script aligns the currently selected, active layer to a Select All "marching ant" selection. The selection and deselection is automatically performed by the script, as they are simply a means to an end. An action could do the same.

So the script doesn't select any layers.

So, are you looking for legacy ExtendScript code to select all floating layers for another task? If so:

app.runMenuItem(stringIDToTypeID('selectAllLayers'));

Otherwise, like the native command or action recording, select all layers will not include a special Background layer, extra steps are required for that (not my code):

selectAllLayers(true); // Change to false to also select the Background layer

function selectAllLayers(ignoreBackground) {
  // Select all layers (doesn't include Background)
  try {
    var desc = new ActionDescriptor();
    var ref = new ActionReference();
    ref.putEnumerated( charIDToTypeID('Lyr '), charIDToTypeID('Ordn'), charIDToTypeID('Trgt') );
    desc.putReference( charIDToTypeID('null'), ref );
    executeAction( stringIDToTypeID('selectAllLayers'), desc, DialogModes.NO );
  } catch(e) {}
  if ( !ignoreBackground ) {
    // Add Background Layer to the selection (if it exists)
    try {
      activeDocument.backgroundLayer;
      var bgID = activeDocument.backgroundLayer.id;
      var ref = new ActionReference();
      var desc = new ActionDescriptor();
      ref.putIdentifier(charIDToTypeID('Lyr '), bgID);
      desc.putReference(charIDToTypeID('null'), ref);
      desc.putEnumerated( stringIDToTypeID('selectionModifier'), stringIDToTypeID('selectionModifierType'), stringIDToTypeID('addToSelection') );
      desc.putBoolean(charIDToTypeID('MkVs'), false);
      executeAction(charIDToTypeID('slct'), desc, DialogModes.NO);
    } catch(e) {}
  }
}

With action you can't do that. With scripting I doubt but you can align to selection / canvas.

The other thread you've created for other problem. After my answer you marked it as correct solution, but then someone unmarked it. I don't know who, maybe you for some reason? Now it's remarked but maybe unnecessarily?

Did you have an Active selection  when  you tried to Record Align Layers to selection? Was there a selection to align to?