Unit 3 — Extended Track

Build the Core app to a higher bar: organized across files, using Python's built-in data tools, and ready for the bigger version of the change request.

This Track Is for You If…

You've finished the Core checklist ideas in your head and want the next layer.
You want to organize a bigger program, and you're comfortable with functions and try/except.

What You'll Build

The same app as Core, from the Unit 3 menu. It also has its data code in a separate file, uses a standard-library tool where it fits, and handles the change request.

Requirements Checklist

Everything on the Core checklist, plus these. (Ticking the boxes is just for you, it doesn't save.)

Everything on the Core checklist
Data code in its own file (for example storage.py), with the menu in main.py. They talk through functions.
A standard-library tool where it fits (collections, json, csv or dataclasses), with a sentence in your README saying why
try / except for a missing file and a damaged file (json.JSONDecodeError)
A docstring on every function, and names that say what each value holds
Feature request triaged, then implemented or declined with a clear reason, and tested
AI Collaboration section filled in

Checkpoints at Extended

Checkpoint	What it looks like at Extended
CP1	Core CP1, plus a short plan for which files your program will have and what each one does
CP2	Core CP2, plus the storage file working on its own (you can call its functions from a test)
CP3	Core CP3, plus the feature request done and tested. The README says which standard-library tool you chose and why.

Start each checkpoint commit with CP1:, CP2: or CP3:, and push before your teacher calls you up.

When You're Stuck

Go back to the matching Unit 3 lesson (3.1 to 3.4), then to the Unit 2 lessons on try/except if you're fixing an error.
Check the imports. If storage.py can't be found, check it's in the same folder as main.py.
Three before me: check your notes, then ask a neighbour, then ask your teacher.

Done Looks Like…

Someone can read your file names and README and tell what each file is for. If you changed the save format, you'd only need to touch storage.py, not main.py.