Reopen preview without restarting server

The current preview experience feels a bit rough around the edges:

• If I close the preview terminal the preview pane stays open pointing to an inexistent server.
• If I close the preview pane the server at the terminal keeps running but...
  • if I then open preview again a new server is launched

The first point may be okeyish. But I believe the second one needs improvement. Closing and opening preview panes is a common operation since the pane uses screen real estate. That the server stays running is a red herring that makes one believe that a new panel will just reconnect to it. Relaunching the server is pointless and a bit slow, also breaks any open connection from an external browser since the port is changed.

Perhaps an option to set the port that, when active, forces the preview pane to reconnect instead of launching a new server (I assume this is because the previous port was lost at that point).

The issue names no files, tests, or entry points. Start by tracing how preview panes launch and track the preview server; done means reopening a pane reconnects to the existing server and preserves its port instead of launching another server.