The build streams live, and a progress rail tracks its five phases: Reserve, Design, Write, Check and Ready. You see the model's reasoning (for the models that reason before writing), then __main__.py line by line as it is written. The plugin's name, summary and slash commands fill in as soon as they are decided, next to the files it will ship: __main__.py, manifest.json, README.md and requirements.txt.
You can leave the page
The build keeps running without you. It lands in Saved builds when it finishes and settles your credits on its own.
When a plugin needs more room
A meter shows how much of the build budget has been used. When a plugin is running large, the builder warns you before it reaches the limit and offers to hold a little more, so the build keeps going without stopping.
If a build does reach its budget, it pauses instead of losing the work. Press Continue building to start a new pass with up to double the room, capped at what the model can write in one pass, or Save & finish later to pick it up from Saved builds. Continuing picks up where the build stopped rather than starting again, and the button shows the extra hold before you press it.