Dialog command

/dialog is a Command introduced in the 25w20a snapshot that can display simple dialog interfaces to the player.

In singleplayer opening a dialog pauses the game like with the pause menu.

Craft a dialog

Create a new Datapack and open it in your favourite code editor. (How to create a datapack)
Create a new json file <datapack>/data/<namespace>/dialog/<name>.json with <name> as a custom name for your dialog.

A base dialog json should have

{
   "type": "minecraft:notice", // The dialog type
   "title": "Dialog", // The dialog title, shown at the top of the dialog
   "body": [ // The dialog content, list of UI elements or only one element
      {
         "type": "plain_message",
         "contents": "Hello world!"
      }
   ]
}

All the dialog syntax is aviable on the Minecraft Wiki .

Display your dialog with /dialog show @s <datapack>:<name>.

Here is a project showcasing the dialog system. Dialog Teleport.

Misode dialog generator

Resources

Minecraft Wiki