Notebooks

In a world, open “Files”. Notebooks are listed under “Notebooks”, each with how many cells it has, and who changed it last and when. “Open” opens one in a window of its own.

The world's owners and builders can make one with “New notebook”, or bring one in with “Import a notebook”: a Jupyter notebook file (.ipynb), from Jupyter, VS Code or a course. Everyone else who reads the world can open and read them.

• Nothing in a notebook runs when you open or import it.

A text cell holds writing (Markdown: headings, lists, links, pictures). A code cell holds Python: press “Run” beside it, or “Shift-Enter”, and what it prints, its tables and its charts show under it. The number beside a code cell, like [3], is the order the cells were run in.

• “+ Code” and “+ Text” add a cell below the one you chose. Each cell has Move up, Move down, “Text” or “Code” to change its kind, and “Delete”. A deleted cell comes back with Z.
• “Run all” runs every cell from the top. “Stop” stops the cell that's running. “Restart” starts Python again, with nothing defined.
• The keys, as the app says them: Shift-Enter runs a cell. Esc, then A or B adds one, D D deletes it, M makes it text, Y makes it code.
• Pictures and tables from earlier runs show as they were kept. Web pages and widgets made by code aren't run, and say “Interactive output, not shown here. Open in VS Code to use it.”
• Pictures from the web in a text cell load only after you press “Show images from the web”, because loading one tells that site who opened the notebook.

It saves as you type, and the line beside its name says “Saving…”, then “Saved”. Offline, it says “Saved on this computer” and catches up when you're back.

• If the same notebook was changed on another device meanwhile, nothing is overwritten. It says, for example, “Changed on Ana's iPhone since. Keep both, or use this one?” “Keep both” keeps yours as a copy beside it; “Use this one” puts yours over the other.
• A notebook is edited in one place at a time. Where it is open on another device, it says “Open on Ana's MacBook. Take over here?”, with “Take over here”.
• Someone who reads the world but doesn't build in it sees “Read only”: they can read it, but not change it.

• A notebook is at most 2 MB and 500 cells, and outputs are kept up to 1 MB in all. A bigger output says “Output too big to keep. Run again to see it.”
• A notebook from a Jupyter older than nbformat 4 can't be imported. It says “This notebook is from an old Jupyter. Open it in Jupyter and save it again.”

Claude Code, Claude, ChatGPT and the other apps connected to Nirvaana can list a world's notebooks and read them, but never change or run them. What they read is marked as the notebook's words, not instructions for them. A notebook in an exam can't be read by them until it's submitted.