Is there a way to make my own save command that overrides the standard file save keybind?

I'm contributing to an open issue regarding keybindings and custom editors. More specifically, if one were to edit a Markdown file in the standard .md text editor then hit CMD+S, not only does VSCode save the edits on the open file, but it also toggles to the Markdown's preview mode.

Right now, I have a custom editor save command in the works, and the constructor/keybindings is as follows (in TypeScript):

(new class SaveCustomEditorCommand extends Command {
    public static readonly ID = 'editor.action.customEditor.save';

    constructor() {
        super({
            id: SaveCustomEditorCommand.ID,
            precondition: CONTEXT_HAS_CUSTOM_EDITORS,
            kbOpts: {
                primary: KeyMod.CtrlCmd | KeyCode.KEY_S,
                weight: KeybindingWeight.EditorContrib
            }
        });
    }
    ... // fully implemented runCommand function
}).register();

As the command is, hitting CMD+S simply saves the changes and nothing more. However, if I were to change the KeyCode from KEY_S to KEY_Y (since CMD+Y isn't an already existing keybinding command), the save-to-preview command works as intended. Setting the weight property inside kbOpts to higher enums does not change anything.

I'm certain that somewhere in VSCode source, the File/Save CMD+S command takes total precedence, but given that my command should be running only under the precondition that the context has custom editors, I was wondering if I can somehow force my "Save and Preview" command to run instead of the simple, universal "Save" command.

Any pointers or guidance would be much appreciated; this is my first contribution to anything open-source!

If keeping CMD+Y is the more feasible course of action for a "Save and Preview" keybinding, then that works for me, but I would like to least try with CMD+S if possible.