Make it so that if the Mermaid diagrams become larger than the screen—either in width or height—they don’t fit entirely on the screen. In such cases, they should be displayed inside a container that shows a small preview, text on blocks is not shown, and only a thumbnail is shown.
"When clicked, the diagram should open in a full-screen Mermaid view that allows users to drag it around and zoom in or out. While there is already a community plugin called ‘Diagram Zoom Drag’ that provides similar functionality, it does not support this feature in editing mode.
maybe it can be a core plugin so you can enable and disable it as you like*