TextFieldState models text, selection and composition together. Editing through its transaction API preserves undo history and cursor position in ways string replacement cannot, which matters for any non-trivial input.
Text height depends on content, font and scale, which makes uniform list rows harder than they look. Line-break strategies, hyphenation and baseline-relative padding are the tools that solve it without fixed heights.
Text takes a String or an AnnotatedString. The second lets one composable carry multiple styles, inline content and clickable spans — replacing the Row of Texts that breaks at large font scales.
MaterialTheme scopes values to a subtree, which is the wrong shape for reusable per-component configuration. Compose's styles direction addresses that gap; wrapper composables are the pattern to use today.
Material models colour, type and shape. Everything else a design system needs — spacing, motion, semantic colour — has to be added. Extending with a parallel CompositionLocal is usually right; a full custom system rarely is.
Material's shape scale gives five corner sizes mapped to component categories. The system is simple; the interesting parts are clip ordering, asymmetric corners, and shapes that must respond to state.
Material's type scale gives fifteen named roles instead of a font-size parameter. Naming the role rather than the size is what makes typography consistent across a team and correct at large font scales.
Dynamic colour derives a full Material scheme from the user's wallpaper. It improves the feel of most apps and destroys brand recognition if applied indiscriminately, so the interesting work is deciding what stays fixed.
MaterialTheme provides three CompositionLocals and a handful of defaults. Understanding its actual shape explains how components pick up styling, why hardcoded values break dark mode, and what a custom theme has to replace.
Material 3's SearchBar transitions into a full-screen suggestion surface, which makes it a navigation concern. Chips come in four semantic variants, and the assist/filter/input/suggestion split matters.
Compose's date and time pickers are straightforward components hiding a genuine trap: the selected value is UTC-midnight epoch millis, and converting it naively shifts dates by one in most of the world.
Compose gives you progress indicators; it doesn't tell you when to show one. Duration decides: under 300ms show nothing, over a second show progress, and never let an indicator replace content that could be a skeleton.
