loc: replace reflection-based args with tuple-params + IDictionary overloads

CONTRIBUTING.md

@@ -175,7 +175,7 @@ Output is the same TAP stream as a normal selftest run. The runner detects AOT a
 
 A native crash terminates the AOT process — the per-fixture managed watchdog can't fire. Iterate by tailing the TAP output for the *last* `# Running: <name>` line before exit, add that name to the skip list, and re-run. Be conservative when wildcarding a family: many `Family_*` fixtures pass even when one member crashes.
 
-**4. Expected pass count.** As of 2026-05-20, an AOT run of the suite produces roughly: 735 fixtures total → 193 skipped, ~542 passed, 0 failed. The skip list covers fixtures that exercise subsystems documented as not-yet-AOT-clean in [`docs/aot-support.md`](docs/aot-support.md) (PropertyGrid auto-discovery, devtools/MCP, UseObservable on POCOs, anonymous-type localization args, theme resource lookup, XAML-metadata-dependent control hosting). When you fix one of those subsystems, drop the corresponding entries from `DefaultAotSkipPatterns`. The non-AOT run on the same commit is 735/735 pass.
+**4. Expected pass count.** As of 2026-05-20, an AOT run of the suite produces roughly: 735 fixtures total → 192 skipped, ~543 passed, 0 failed. The skip list covers fixtures that exercise subsystems documented as not-yet-AOT-clean in [`docs/aot-support.md`](docs/aot-support.md) (PropertyGrid auto-discovery, devtools/MCP, UseObservable on POCOs, theme resource lookup, XAML-metadata-dependent control hosting). When you fix one of those subsystems, drop the corresponding entries from `DefaultAotSkipPatterns`. The non-AOT run on the same commit is 735/735 pass.
 
 ### 3. E2E tests (`tests/Reactor.AppTests`) — MSTest + WinAppDriver
 

docs/_pipeline/apps/localization/App.cs

@@ -69,7 +69,7 @@ public override Element Render()
         var title = intl.Message(new MessageKey("App", "title"));
         var greeting = intl.Message(
             new MessageKey("App", "greeting"),
-            new { name = "Alice" });
+            ("name", "Alice"));
 
         return VStack(12,
             TextBlock(title).FontSize(24).Bold(),
@@ -156,7 +156,7 @@ public override Element Render()
                     var title = intl.Message(new MessageKey("App", "title"));
                     var greeting = intl.Message(
                         new MessageKey("App", "greeting"),
-                        new { name = "World" });
+                        ("name", "World"));
                     return VStack(4,
                         TextBlock(title).FontSize(18).Bold(),
                         TextBlock(greeting));

docs/_pipeline/templates/localization.md.dt

@@ -56,7 +56,10 @@ picks up the new locale automatically.
 
 Call `UseIntl()` in any descendant — it is a [hook](hooks.md) — to get the
 `IntlAccessor`. Use `.Message()` to look up translated strings by key. Pass
-arguments as an anonymous object for interpolation:
+arguments as `("name", value)` tuples for interpolation — the first item is
+the placeholder name as a string literal (matching the `{name}` in the
+`.resw` pattern), the second is the value. This is the compact, AOT-safe
+shape supported by the tuple-params overload:
 
 ```csharp snippet="localization/useintl-messages"
 ```

docs/aot-support.md

@@ -31,7 +31,6 @@ These subsystems compile cleanly with `IsAotCompatible=true` (the warnings are s
 | **DataGrid `AutoColumns<T>`** | Reflects over `T`'s public properties via `TypeRegistry`. The `T` parameter is annotated `[DynamicallyAccessedMembers(PublicProperties)]` so the trimmer keeps the members, but `AutoColumns` ultimately funnels into `TypeRegistry.Resolve`, which is `RequiresUnreferencedCode`. Use explicit `Column<T,V>(…)` definitions instead. | Issue #70 |
 | **`UseObservable` on POCOs** | `ObservableTreeTracker` walks public properties via reflection to subscribe to INPC. Observables built explicitly (`Observable<T>`, `IObservableCollection`) are fine; the implicit-INPC path is not. | Issue #70 |
 | **Form validation** | `FormField`'s default editor resolution goes through `TypeRegistry`. Same caveat as PropertyGrid. | Issue #70 |
-| **Localization with anonymous-type args** | `t.Message(Loc.X, new { count = 3 })` reflects over the anonymous type to build the ICU args dictionary. Use `t.Message(Loc.X, new Dictionary<string, object> { ["count"] = 3 })` under AOT. | Issue #70 |
 | **Navigation state JSON** | `NavigationHandle` serializes deep-link state via `JsonSerializer` without a source-generated context. Custom types that ride through navigation state will fail to serialize under AOT. | Issue #70 |
 | **Component discovery (`ReactorApp.Run<TApp>` reflection paths)** | The instantiation of `TApp` itself is annotated and works. The devtools-only `--list-components` enumeration scans `Assembly.GetTypes`; that path is gated to non-AOT builds. | Issue #70 |
 | **Theme resource lookup (`Theme.X`, `ThemeRef.Resolve`)** | `ThemeRef.Resolve` walks `Application.Current.Resources` + its merged/theme dictionaries. The token records (`Theme.Accent`, `Theme.PrimaryText`, …) construct fine, but at runtime the `XamlControlsResources` entries that `ReactorApplication.xaml` brings in aren't fully populated under AOT — `Resolve` returns `null` for keys that exist under the JIT. Brushes applied via `.Foreground(Theme.X)` will fall back to control defaults. | Issue #70 |

docs/guide/localization.md

@@ -90,7 +90,10 @@ picks up the new locale automatically.
 
 Call `UseIntl()` in any descendant — it is a [hook](hooks.md) — to get the
 `IntlAccessor`. Use `.Message()` to look up translated strings by key. Pass
-arguments as an anonymous object for interpolation:
+arguments as `("name", value)` tuples for interpolation — the first item is
+the placeholder name as a string literal (matching the `{name}` in the
+`.resw` pattern), the second is the value. This is the compact, AOT-safe
+shape supported by the tuple-params overload:
 
 ```csharp
 class LocalizedContent : Component
@@ -101,7 +104,7 @@ class LocalizedContent : Component
         var title = intl.Message(new MessageKey("App", "title"));
         var greeting = intl.Message(
             new MessageKey("App", "greeting"),
-            new { name = "Alice" });
+            ("name", "Alice"));
 
         return VStack(12,
             TextBlock(title).FontSize(24).Bold(),
@@ -228,7 +231,7 @@ class PseudoLocDemo : Component
                     var title = intl.Message(new MessageKey("App", "title"));
                     var greeting = intl.Message(
                         new MessageKey("App", "greeting"),
-                        new { name = "World" });
+                        ("name", "World"));
                     return VStack(4,
                         TextBlock(title).FontSize(18).Bold(),
                         TextBlock(greeting));

docs/guide/navigation.md

@@ -640,10 +640,10 @@ class DiagnosticsDemo : Component
 
         UseEffect(() =>
         {
-            Action<NavigationDiagnosticEvent> onRequested =
-                e => updateLog(l => [.. l, $"Requested: {e.From} → {e.To}"]);
-            Action<NavigationDiagnosticEvent> onCompleted =
-                e => updateLog(l => [.. l, $"Completed: {e.To}"]);
+            EventHandler<NavigationDiagnosticEvent> onRequested =
+                (_, e) => updateLog(l => [.. l, $"Requested: {e.From} → {e.To}"]);
+            EventHandler<NavigationDiagnosticEvent> onCompleted =
+                (_, e) => updateLog(l => [.. l, $"Completed: {e.To}"]);
 
             NavigationDiagnostics.NavigationRequested += onRequested;
             NavigationDiagnostics.NavigationCompleted += onCompleted;

docs/reference/localization-howto.md

@@ -379,7 +379,7 @@ public override Element Render()
 
     return VStack(
         Text(t.Message(Loc.MyComponent.Title)),
-        Text(t.Message(Loc.MyComponent.ItemCount, new { count = items.Count })),
+        Text(t.Message(Loc.MyComponent.ItemCount, ("count", items.Count))),
         Text(t.FormatDate(DateTimeOffset.Now)),
         Text(t.FormatNumber(price)),
         Text(t.FormatList(names, ListFormatType.Conjunction))

src/Reactor.Cli/Loc/SourceRewriter.cs

@@ -75,16 +75,21 @@ private static string BuildReplacement(KeyedLocString entry)
             var argParts = new List<string>();
             foreach (var param in icuParams)
             {
+                // The ICU param name becomes a string literal in the emitted
+                // source, so it has to be C#-escaped. Most ICU params are
+                // identifiers, but the spec doesn't forbid `"` or `\` —
+                // FormatLiteral keeps the emission valid in those cases.
+                var keyLit = SymbolDisplay.FormatLiteral(param, quote: true);
                 if (argMap.TryGetValue(param, out var exprText) && param != exprText)
-                    argParts.Add($"{param} = {exprText}");
+                    argParts.Add($"({keyLit}, {exprText})");
                 else
-                    argParts.Add(param); // direct variable reference
+                    argParts.Add($"({keyLit}, {param})");
             }
 
             if (argParts.Count > 0)
             {
                 var args = string.Join(", ", argParts);
-                return $"t.Message({locPath}, new {{ {args} }})";
+                return $"t.Message({locPath}, {args})";
             }
         }
 

src/Reactor/Core/Localization/IntlAccessor.cs

@@ -1,8 +1,5 @@
-using System.Collections.Concurrent;
-using System.Diagnostics.CodeAnalysis;
 using System.Diagnostics.Tracing;
 using System.Globalization;
-using System.Reflection;
 using System.Text.RegularExpressions;
 using Microsoft.UI.Reactor.Core;
 using Microsoft.UI.Reactor.Core.Diagnostics;
@@ -22,7 +19,6 @@ public sealed class IntlAccessor
     private readonly CultureInfo _culture;
     private readonly bool _pseudoLocalize;
     private readonly Dictionary<string, string> _assetCache = new();
-    private static readonly ConcurrentDictionary<Type, PropertyInfo[]> _propertyCache = new();
 
     public IntlAccessor(
         string locale,
@@ -55,7 +51,7 @@ public IntlAccessor(
     /// Loads a string resource by key, then formats it with ICU MessageFormat.
     /// Falls back to the default locale if the key is missing in the current locale.
     /// </summary>
-    public string Message(MessageKey key, object? args = null)
+    public string Message(MessageKey key, IDictionary<string, object>? args = null)
     {
         var pattern = ResolvePattern(key);
         if (pattern is null)
@@ -64,13 +60,9 @@ public string Message(MessageKey key, object? args = null)
         string result;
         try
         {
-            if (args is null)
-                result = _messageCache.Format(Locale, pattern);
-            else
-            {
-                var dict = ToArgsDictionary(args);
-                result = _messageCache.Format(Locale, pattern, dict);
-            }
+            result = args is null
+                ? _messageCache.Format(Locale, pattern)
+                : _messageCache.Format(Locale, pattern, args);
         }
         catch (Exception ex)
         {
@@ -84,6 +76,27 @@ public string Message(MessageKey key, object? args = null)
         return _pseudoLocalize ? PseudoLocalizer.Transform(result) : result;
     }
 
+    /// <summary>
+    /// Compact tuple-args overload for the common case of formatting a single
+    /// message with a handful of ICU placeholders. Builds a plain
+    /// <see cref="Dictionary{TKey, TValue}"/> in-place — no reflection, AOT-safe.
+    /// </summary>
+    /// <remarks>
+    /// Tuples with a null <c>Value</c> are dropped before the dictionary is
+    /// built — this matches the behavior of the prior reflection path, which
+    /// skipped null-valued properties so the formatter saw the placeholder as
+    /// "missing" rather than substituting an empty string.
+    /// </remarks>
+    /// <example>
+    /// <code>
+    /// t.Message(Greeting, ("name", "World"));
+    /// t.Message(SearchResults, ("count", 0), ("query", "test"));
+    /// </code>
+    /// </example>
+    public string Message(MessageKey key, (string Name, object? Value) arg1,
+        params (string Name, object? Value)[] more)
+        => Message(key, BuildArgs(arg1, more));
+
     /// <summary>
     /// Formats a message that contains rich text tags (e.g., &lt;bold&gt;text&lt;/bold&gt;),
     /// mapping each tag to an element factory. Returns a GroupElement containing the
@@ -95,7 +108,7 @@ public string Message(MessageKey key, object? args = null)
     /// rendered as plain text (tag markers stripped). Nested tags are not supported — only
     /// the outermost tag is processed.
     /// </remarks>
-    public Element RichMessage(MessageKey key, object? args = null,
+    public Element RichMessage(MessageKey key, IDictionary<string, object>? args = null,
         Dictionary<string, Func<string, Element>>? tags = null)
     {
         var pattern = ResolvePattern(key);
@@ -116,8 +129,7 @@ public Element RichMessage(MessageKey key, object? args = null,
                 // BEFORE formatting so a translator-controlled arg can't
                 // mint a `<link>` tag that ParseRichText would dispatch to a
                 // developer-supplied factory.
-                var dict = ToArgsDictionary(args);
-                var escaped = EscapeForRichTags(dict);
+                var escaped = EscapeForRichTags(args);
                 formatted = _messageCache.Format(Locale, pattern, escaped);
             }
         }
@@ -137,6 +149,17 @@ public Element RichMessage(MessageKey key, object? args = null,
         return ParseRichText(formatted, tags);
     }
 
+    /// <summary>
+    /// Compact tuple-args overload of the dict-based <c>RichMessage</c> —
+    /// same allocation profile as the tuple-args <c>Message</c> overload.
+    /// Tags must be supplied via the dict-based overload; this variant is for
+    /// the common case where the developer just wants the formatted text.
+    /// Null-valued tuples are dropped (see the tuple-args <c>Message</c> remarks).
+    /// </summary>
+    public Element RichMessage(MessageKey key, (string Name, object? Value) arg1,
+        params (string Name, object? Value)[] more)
+        => RichMessage(key, BuildArgs(arg1, more));
+
     /// <summary>
     /// Resolves a locale-qualified asset path. Falls back to the unqualified path
     /// if no locale-specific asset exists.
@@ -334,47 +357,20 @@ private static Element ParseRichText(string formatted, Dictionary<string, Func<s
         return null;
     }
 
-    [UnconditionalSuppressMessage("Trimming", "IL2026", Justification = "ToArgsDictionary uses reflection on anonymous types for localization args.")]
-    [UnconditionalSuppressMessage("Trimming", "IL2070", Justification = "ToArgsDictionary uses reflection on anonymous types for localization args.")]
-    private static IDictionary<string, object> ToArgsDictionary(object args)
-    {
-        if (args is IDictionary<string, object> dict)
-            return dict;
-
-        // SECURITY (TASK-051): refuse arbitrary DTOs. Anonymous types and the
-        // [LocArgs]-marked record contract are the only accepted shapes;
-        // anything else (e.g. a domain DTO with `AccessToken`/`Email`/...)
-        // would expose every public property to translator-controlled patterns.
-        var type = args.GetType();
-        if (!IsAcceptableArgsContainer(type))
-            throw new ArgumentException(
-                $"Localization args must be an IDictionary<string,object>, an anonymous type, or a record marked with [LocArgs]. Got '{type.FullName}'.",
-                nameof(args));
-
-        var result = new Dictionary<string, object>();
-        var props = _propertyCache.GetOrAdd(type,
-            t => t.GetProperties(BindingFlags.Public | BindingFlags.Instance));
-        foreach (var prop in props)
-        {
-            var value = prop.GetValue(args);
-            if (value is not null)
-                result[prop.Name] = value;
-        }
-        return result;
-    }
-
-    private static bool IsAcceptableArgsContainer(Type type)
+    // Null-valued tuples are skipped so the formatter sees a "missing"
+    // placeholder rather than receiving a null arg — preserves the behavior
+    // of the prior reflection path, which dropped null-valued properties.
+    private static Dictionary<string, object> BuildArgs(
+        (string Name, object? Value) arg1,
+        (string Name, object? Value)[] more)
     {
-        // Anonymous types are sealed, generic, public-property-only with a
-        // compiler-generated name like `<>f__AnonymousType0`.
-        if (type.Name.StartsWith("<>", StringComparison.Ordinal)) return true;
-        // Allow opt-in via [LocArgs] attribute name match.
-        foreach (var attr in type.GetCustomAttributes(inherit: false))
+        var dict = new Dictionary<string, object>(more.Length + 1);
+        if (arg1.Value is not null) dict[arg1.Name] = arg1.Value;
+        foreach (var (k, v) in more)
         {
-            var n = attr.GetType().Name;
-            if (n == "LocArgsAttribute" || n == "LocArgs") return true;
+            if (v is not null) dict[k] = v;
         }
-        return false;
+        return dict;
     }
 
     /// <summary>
@@ -403,7 +399,7 @@ private static string SanitizeBidi(string text)
 
     /// <summary>
     /// HTML-escapes string-valued args before they are substituted into a
-    /// pattern that <see cref="RichMessage"/> will tag-parse. TASK-053.
+    /// pattern that the <c>RichMessage</c> overloads will tag-parse. TASK-053.
     /// Non-string values pass through untouched.
     /// </summary>
     private static IDictionary<string, object> EscapeForRichTags(IDictionary<string, object> args)

tests/Reactor.AppTests.Host/Fixtures/LocalizationFixtures.cs

@@ -136,18 +136,18 @@ public override Element Render()
                 VStack(8,
                     TextBlock(t.Message(AppTitle)).Set(tb => tb.FontSize = 24).AutomationId("LocTitle"),
                     TextBlock(t.Message(Welcome)).AutomationId("LocWelcome"),
-                    TextBlock(t.Message(Greeting, new { name = "World" })).AutomationId("LocGreeting"),
+                    TextBlock(t.Message(Greeting, ("name", "World"))).AutomationId("LocGreeting"),
 
                     // Plural scenarios
-                    TextBlock(t.Message(ItemCount, new { count = 0 })).AutomationId("LocPluralZero"),
-                    TextBlock(t.Message(ItemCount, new { count = 5 })).AutomationId("LocPluralFive"),
+                    TextBlock(t.Message(ItemCount, ("count", 0))).AutomationId("LocPluralZero"),
+                    TextBlock(t.Message(ItemCount, ("count", 5))).AutomationId("LocPluralFive"),
 
                     // Search-results with multiple plural + param
-                    TextBlock(t.Message(SearchResults, new { count = 0, query = locale == "ko-KR" ? "\ud14c\uc2a4\ud2b8" : "test" }))
+                    TextBlock(t.Message(SearchResults, ("count", 0), ("query", locale == "ko-KR" ? "\ud14c\uc2a4\ud2b8" : "test")))
                         .AutomationId("LocSearchZero"),
-                    TextBlock(t.Message(SearchResults, new { count = 1, query = locale == "ko-KR" ? "\ud14c\uc2a4\ud2b8" : "test" }))
+                    TextBlock(t.Message(SearchResults, ("count", 1), ("query", locale == "ko-KR" ? "\ud14c\uc2a4\ud2b8" : "test")))
                         .AutomationId("LocSearchOne"),
-                    TextBlock(t.Message(SearchResults, new { count = 42, query = locale == "ko-KR" ? "\ud14c\uc2a4\ud2b8" : "test" }))
+                    TextBlock(t.Message(SearchResults, ("count", 42), ("query", locale == "ko-KR" ? "\ud14c\uc2a4\ud2b8" : "test")))
                         .AutomationId("LocSearchMany"),
 
                     // Direction label