halkyon/packages/halkyon_ui/README.md
Tizian 「ティツィアーン」 1b62c8098c
docs: one repository for every app and shared package (ADR 0015)
The root AGENTS.md holds what applies to every app and package (how
work is done, Serverpod, checks with Melos and the tools, CI); Learn's
own is apps/learn/AGENTS.md, Todo's a note that it is still the
scaffold. The root README introduces the project, Learn's moves to its
folder; LICENSE.md says which licence covers which directory, Todo's
packages unlicensed until decided; one CONTRIBUTING.md. ADR 0015
records the decision; ADR 0014 and 0003 note what moved.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
2026-10-22 18:11:04 +02:00

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# halkyon_ui
Halkyon's look, shared by its apps (Learn, Todo, Train): one theme around the
kingfisher's cobalt and copper, the bundled Noto Sans, Material 3's window
sizes, and the widgets every app's screens are built of, with their texts in
British English, American English and German.
Written as the apps are: Dart 3.13's primary constructors, Material from
`package:material_ui` (never `package:flutter/material.dart`), Lucide icons,
LeanCode's lints.
## What it holds
- **Theme** (`lib/src/theme/`): `appTheme(brightness, extensions: …)`, Material
3 with hand-written light and dark schemes (primary cobalt, tertiary copper,
cobalt-tinted neutrals), Material 3 Expressive's 64 dp navigation bar, flat
app bars, floating snack bars; `Brand`; `ThemeExtras`, the status colours
Material has no role for (`Theme.of(context).extras`); `PaletteColor`, the
20 colours a person can give content, each with a text colour held to WCAG
AA by a test; `FittedSnackBars`.
- **Fonts**: Noto Sans for Latin, Greek and Cyrillic, every weight in one
variable file, as `appFontFamily` (`packages/halkyon_ui/Noto Sans`). Chinese,
Japanese and Korean fall back to `Noto Sans JP`, `SC`, `TC` and `KR`, which
an app bundles itself if it needs them (`appFontFallbackFor` puts a
language's own first).
- **Layout** (`lib/src/layout/`): `WindowSize` (`context.windowSize`) and
`readableContentMaxWidth`.
- **Widgets** (`lib/src/widget/`): `showAdaptiveSheet` with `SheetScaffold`;
`TopGradient`, `ScreenTint`, `ScreenColor`, `TintFrame`, `FramedScreen`
and `TabVisibility`; `FloatingNavigationBar`; `AppLoadingIndicator`,
`ButtonLoadingIndicator`, `AppRefreshIndicator`; `SectionCard`,
`SliverCentered`, `EmptyListMessage`, `CountBadge`, `TitleWithKicker`,
`CollapsingRow`, `ScrollHidingFab`, `liftWhileDragged`, `ReorderToggle`,
`ReorderGrip`; `ChevronField`, `requiredDecoration`, `FieldInfoButton`,
`CountStepper`, `PaletteColorPicker`, `TextLimits` with
`nearLimitCounter`; `confirmDestructiveAction`, `showUndoSnackBar`,
`showMoreInfoSheet`; `FoundById`; `KeyboardBackOnResume`; `BrandWordmark`
and `LaunchScreen`, which take the app's word and icon.
What belongs to one app stays in it: its own colours (an extension passed to
`appTheme`), routes, repositories, editors and texts.
## Using it in an app
Depend on it by path, within the repository's workspace (an app's packages sit in
`apps/<app>/`), so a change to the package and to the apps using it is one commit:
```yaml
dependencies:
halkyon_ui:
path: ../../../packages/halkyon_ui
```
Then set the app up as `example/lib/main.dart` does:
```dart
MaterialApp(
theme: appTheme(Brightness.light, extensions: [MyColors.light]),
darkTheme: appTheme(Brightness.dark, extensions: [MyColors.dark]),
localizationsDelegates: const [
AppLocalizations.delegate,
HalkyonUiLocalizations.delegate,
// material_ui's: flutter_localizations' serve only the SDK's Material.
...GlobalMaterialLocalizations.delegates,
],
supportedLocales: AppLocalizations.supportedLocales,
builder: (context, child) => FittedSnackBars(child: child!),
…
);
```
and call `registerFontLicenses()` at start. An app bundling the CJK fonts
declares them in its own `pubspec.yaml` under exactly the names
`appFontFallback` lists (no `packages/` prefix) and registers their licence
itself.
## Texts
`lib/l10n/halkyon_ui_en.arb` is the template (British English, also the
fallback); `halkyon_ui_de.arb` German, informal "du"; `halkyon_ui_en_US.arb`
only what American English spells differently; `halkyon_ui_en_GB.arb` empty. A
new text goes into the template and German together (`test/l10n/` fails
otherwise). `flutter pub get` writes `lib/l10n/halkyon_ui_localizations*.dart`,
which are committed and never edited or
formatted by hand.
## Checks
From the workspace root: `dart analyze --fatal-infos`; then `flutter test` in
`packages/halkyon_ui` and in `packages/halkyon_ui/example`, whose tests check
what only an app sees (the font under the name an app finds it by, its
licence).