What you are building
Brushnook is a paint app you assemble in twelve short stages. The teaching stack is Qt Quick (Python 3, PySide6, Qt Quick QML). By the end you should understand the shell, the data you persist, and the everyday workflows people expect from this kind of app.
Qt Quick (QML) is a different path from widgets—declarative UI plus a Canvas for drawing strokes.
Expose brush settings from Python to QML. Keep the stroke list serializable so undo stays understandable.
Work in order. Early folders are intentionally small so you can see the window (or server) boot before features pile on. From the data-layer part onward, each snapshot should still run after you install dependencies.
Read the goal, clone the matching GitHub folder, run it, then skim the code against the notes below. If something fails, fix the run path first—most “bugs” on day one are the wrong directory or a skipped install.
Parts in order
Each chapter below is one checkpoint. Open a part when you are ready for that feature—not all at once.