Layout engine (Milestone 2)

Status: complete (v0.2.0+).

Flutter-like layout widgets and a replaceable theme seam — built on top of Milestone 1 without breaking existing APIs.

Layout widgets

Widget	Role
`Row`	Horizontal flex: justify, align, gap
`Column`	Vertical flex: align, gap
`Center`	Flex-center children
`Padding`	Spacing wrapper — prefer fluent `Padding::make()->x(6)->y(4)->child(...)`
`Spacer`	Flex grow empty space
`Expanded`	Flex grow around one child
`SizedBox`	Explicit width/height
`Stack`	Relative layer context (absolute children later)
`Divider`	Semantic `<hr>`
`Scaffold`	App shell slots: appBar, sidebar, body, footer

Flutter-style composition

use Serixa\Component\Button;
use Serixa\Component\Center;
use Serixa\Component\Column;
use Serixa\Component\SizedBox;
use Serixa\Component\Text;
use Serixa\Rendering\Renderer;

$html = (new Renderer())->render(
    Center::make(
        Column::make([
            Text::make('Welcome'),
            SizedBox::height(20),
            Button::make('Continue')->primary()->large(),
        ]),
    ),
);

Array or variadic children are supported on layout widgets:

Column::make([Text::make('A'), Text::make('B')]);
Column::make(Text::make('A'), Text::make('B'));

Padding (fluent)

Preferred:

Padding::make()
    ->x(6)
    ->y(4)
    ->child(Text::make('Inset'));

Deprecated static factories still work (Padding::all(4), Padding::x(2, $child), …) via __callStatic so instance methods can share the same names.

Scaffold

Structural application shell (no routing/auth):

use Serixa\Component\Scaffold;

Scaffold::make()
    ->appBar(Text::make('Top'))
    ->sidebar(Text::make('Nav'))
    ->body(Text::make('Page'))
    ->footer(Text::make('Foot'));

Theme seam

Widgets never hard-code Tailwind. They resolve classes through:

ThemeManager::current()->classes('row', ['justify' => 'between', 'gap' => 4]);

Convenience shortcuts (for docs and apps):

ThemeManager::current()->buttonPrimary();

Swap themes without touching widget code:

ThemeManager::set(new MyBootstrapTheme());

DefaultTheme is the Tailwind implementation. Future Material/Bootstrap themes implement ThemeInterface.

SizedBox note

PHP cannot define static and instance methods with the same name. Use:

SizedBox::height(20) / SizedBox::width(32) — factories
->withWidth() / ->withHeight() — chain the other axis

Backward compatibility

Milestone 1 APIs remain: variant(), size(), Container::make(...$children), etc. Milestone 2 only adds fluent aliases (primary(), large(), rounded()) and moves class maps into the theme.

Out of scope

Routing, forms, auth, ORM, CLI, HTTP, and a Page widget (compose with Center / Column / Container instead).

Layouts