feat: add locale-aware formatting utilities

Author: Roy Lin

Cargo.lock

@@ -116,8 +116,12 @@ gtk4 = []
 gtk4-native = ["gtk4", "dep:gtk4_crate"]
 
 [dependencies]
+fixed_decimal = { version = "0.7.2", features = ["ryu"] }
 icu_collator = "2.2.1"
+icu_datetime = "2.2.0"
+icu_decimal = { version = "2.2.0", features = ["alloc"] }
 icu_locale_core = "2.2.0"
+icu_provider = { version = "2.2.0", features = ["sync"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 swc_atoms = { version = "9.0.3", optional = true }

Cargo.toml

@@ -25,9 +25,10 @@ object graph at the host boundary.
   touch/pen long-press selection entry, collection keyboard navigation,
   hierarchical tree expansion, activation-ordered overlay dismissal, modal
   background inertness, nested focus containment/restoration, typed anchored
-  overlay placement, inherited locale/direction, versioned capability
-  reporting, shared native event-source state machines, and accessibility
-  conformance checks. Versioned native-input manifests expand every role marked
+  overlay placement, inherited locale/direction, locale-aware collation and
+  decimal/date/time formatting, versioned capability reporting, shared native
+  event-source state machines, and accessibility conformance checks. Versioned
+  native-input manifests expand every role marked
   native into strict OS-automation cases; adapter and headless traces cannot
   satisfy that evidence gate.
   A WinUI smoke runner records real XAML Button and list-item mouse and keyboard
@@ -40,8 +41,9 @@ object graph at the host boundary.
   Populating the AppKit and GTK4 manifests with real platform automation,
   role-edge input parity, real-platform layout-aware page-navigation fixtures,
   IME/dead-key conformance, measured overlay collision/arrow conformance and
-  scroll locking, remaining native focus conformance, and locale formatting
-  are still in progress.
+  scroll locking, remaining native focus conformance, message catalogs,
+  currency/percent/unit and date-range/time-zone formatting are still in
+  progress.
 - `.rsx` component source modules with imports, local Rust types, hook
   registrations, Rust selector/reducer expressions, and a final `rsx!(...)`
   view.

README.md

@@ -452,6 +452,17 @@ prefers the GDK Unicode scalar over its symbolic key name, and WinUI uses
 `ToUnicode` with the active keyboard layout and the non-mutating flag before
 falling back to a stable virtual-key name. Full IME and dead-key composition
 remains an adapter conformance gap.
+`I18nManager` also resolves that inherited locale for reusable
+`LocaleCollator`, `LocaleNumberFormatter`, and `LocaleDateFormatter` objects.
+The public collator exposes search/sort usage, ECMA-402 sensitivity,
+case-first, and numeric ordering. Decimal formatting exposes grouping,
+sign-display, and bounded fraction digits with half-expand rounding. Date and
+time formatting exposes short through full styles, optional seconds, calendar
+selection, numbering systems, and hour-cycle overrides through BCP 47 Unicode
+extensions. These formatters use compiled ICU4X data, are `Send + Sync`, and
+perform no platform, file, or network I/O. The collection typeahead path uses
+the same public collator implementation so interactive search and application
+sorting cannot drift to separate locale rules.
 AppKit keeps logical item identity separate from the collection selection
 target: a row button is registered as the ListBoxItem or TreeItem responder,
 while activation reports the selected value to the owning collection.

docs/architecture.md

@@ -256,7 +256,13 @@ The first shared interaction milestone is available in the portable runtime:
 - `I18nManager` projects inherited locale and writing direction through the
   keyed native tree. Scoped overrides and default locale changes are preserved
   across rerenders, and BCP 47 language/script subtags provide deterministic
-  RTL inference.
+  RTL inference. It creates reusable, thread-safe `LocaleCollator`,
+  `LocaleNumberFormatter`, and `LocaleDateFormatter` values from the effective
+  node locale. Collation covers search/sort sensitivity, case-first, and
+  numeric ordering; stable ICU4X decimal formatting covers grouping, signs,
+  and fraction digits; date/time formatting covers localized short through
+  full styles, seconds, calendar, numbering-system, and hour-cycle locale
+  extensions. Collection typeahead reuses this public collator.
 - Native IR capabilities are versioned. Every host exposes a feature manifest
   with unsupported, portable, or native support levels, role-specific
   overrides, and auditable capability issues. Protocol render responses carry
@@ -375,7 +381,7 @@ props:
 | P1 | Event propagation | Add platform-run conformance fixtures for conditional `Stop`/`Continue` across nested native controls. |
 | P1 | Focus management | Add platform-run conformance fixtures for post-mount `autoFocus`, nested containment, and restoration. |
 | P1 | Collections and selection | Complete IME/dead-key typeahead conformance and add real-platform fixtures for layout-aware page navigation. |
-| P1 | Internationalization | Add message formatting, number/date formatting, locale-aware collation, and localized interaction behavior on top of inherited locale/direction. |
+| P1 | Internationalization | Add message formatting, currency/percent/unit number styles, date ranges/time zones, and localized input behavior. Reusable decimal/date/time formatting and locale-aware collation now build on inherited locale/direction. |
 | P1 | Accessibility conformance | Complete OS accessibility API projection, relationships, live regions, value announcements, and role-specific native adapter coverage. |
 | P2 | Overlays | Complete measured boundary-driven collision and arrow projection, native scroll locking, configurable outside-interaction filters, multi-window layer coordination, and real-platform positioning conformance fixtures. |
 | P2 | Capability enforcement | Turn reported capability gaps into adapter policy and conformance gates where portable fallback is not sufficient. |

docs/react-aria-native.md

@@ -19,6 +19,9 @@ pub enum GuiError {
     InvalidTree {
         message: String,
     },
+    Internationalization {
+        message: String,
+    },
     Host {
         message: String,
     },
@@ -41,6 +44,9 @@ impl Display for GuiError {
                 write!(f, "missing required prop {prop:?} on component {component}")
             }
             GuiError::InvalidTree { message } => write!(f, "invalid native UI tree: {message}"),
+            GuiError::Internationalization { message } => {
+                write!(f, "internationalization error: {message}")
+            }
             GuiError::Host { message } => write!(f, "native host error: {message}"),
         }
     }
@@ -60,4 +66,10 @@ impl GuiError {
             message: message.into(),
         }
     }
+
+    pub fn internationalization(message: impl Into<String>) -> Self {
+        GuiError::Internationalization {
+            message: message.into(),
+        }
+    }
 }