A few things outside what you named that are still worth knowing (not extra tools to install as products):
- You will need **system packages** for GTK4 and the C toolchain (libgtk-4-dev, CMake, Ninja). The agent can install them, but you should approve those commands.
- Put the project in its **own empty folder** and git init it. /undo helps; git is the real safety net.
- **Contributor** means Meta may train on prompts and code you send. Fine for this exercise; do not point it at private work later without switching model IDs.