Where to go next

The counter is a small app that exercised the whole path: a native window with the platform's own controls, a React frontend, native storage, a menu, signing for two stores, scripted store assets, and a deploy that produced a submittable bundle.

What you touched, and where it is covered properly:

Topic	Book
The language: types, generics, traits, optionals, error handling	Language Reference
std: collections, JSON, filesystem, processes, networking	Standard Library
The CLI, peko.toml, packages, the registry	CLI and Projects
Windows, menus, storage, the bridge, pop-ups, mobile	Building UIs
C interop, external declarations, Box<T>, manual memory	Low Level

A few things the counter did not need:

• A real menu bar. Delete use_html_menu() and call set_menu with the same action ids. The React handler does not change.
• Pop-up windows. peko.windows.open('/route') opens an app route as a dialog on desktop and a sheet on mobile.
• Mobile. ios and android are already in target_platforms. The frameless chrome collapses to a plain header on a phone, which is why Toolbar and platform.mobile exist.
• Recordings. s.recording(...) scripts the same way a screenshot does and produces the video some stores accept.