Casette: a simple CAS calculator and SageMath frontend.

I spent a year doing Math Academy, starting with a grim confrontation with fractions and ending with multivariable calculus. Starting with MVC, after earning the privilege by grinding months of trig identity integrals, I adopted SageMath as my daily companion.

Sage is fantastic, but it's 2026, and CLI/TUI interfaces are obsolete. The Sage REPL is not especially discoverable (I was today less 1 month old when I discovered '_'). I would rather eat a bug than write Python directly into a Jupyter notebook.

So this:

• It's a calculator.

• It keeps a running tape of expressions.

• You can click an expression to expand, simplify, transpose, or take a derivative of a prior value.

• You can refer to prior values by their entry number on the tape, like diff(#13, x).

• It renders LaTeX math.

• In addition to accepting straight Sage-flavored Python, there's also a poorly-documented and somewhat extensive shortcut syntax, and a graphical formula expander that I shoplifted from Numbers.app.

• It accepts Matlab matrix definition notation.

It will probably get better. Importantly: this repo should be pretty discoverable for Claude or Codex; it has a straightforward design, and it's basically pure SwiftUI surfacing stuff from a SageMath process. Knock yourself out!