day-cli

The day command line: create, build, run, test, and package Day apps.

day new app hello         # a working project: Day.toml, src/, a starter UI
day launch -p macos-appkit -p android-widget
day doctor                # what's installed, what's missing, how to fix it
day pack -p macos-appkit  # a signed .dmg; .ipa, .apk, .flatpak, .msix, .hap per target

Building for seven toolkits normally means juggling seven build systems — cargo, xcodebuild, Gradle, hvigor, resource compilers, code signing. day drives all of them, in parallel when you ask for several targets at once, so a Day project keeps no platform build files of its own beyond the small checked-in scaffolds.

It is also built for automation. Every command has a JSON output mode, day drive steps through a running app one action at a time (the tool coding agents use), and day mcp-server offers the same tools over the Model Context Protocol.

Install it with cargo install --locked day-cli, then run day new.

Part of Day

This crate is one piece of Day, a Rust framework for building apps out of each platform's real native widgets — AppKit, UIKit, Android's Material widgets, GTK 4, Qt 6, WinUI, and ArkUI — from one codebase. There is no web view and no bundled rendering engine: when you write button("Save"), macOS shows an NSButton and Android shows a Material button.

New to Day? Start at daybrite.dev, or browse the source repository.