feat(html): restore context mutators

Co-Authored-By: Virgil <virgil@lethean.io>

context.go

@@ -72,7 +72,31 @@ func NewContext(locale ...string) *Context {
 // An optional locale may be provided as the second argument.
 func NewContextWithService(svc Translator, locale ...string) *Context {
 	ctx := NewContext(locale...)
+	return ctx.SetService(svc)
+}
+
+// context.go: SetService swaps the translator used by the context.
+// Example: ctx.SetService(svc).
+func (ctx *Context) SetService(svc Translator) *Context {
+	if ctx == nil {
+		return nil
+	}
+
+	ensureContextDefaults(ctx)
 	ctx.service = svc
 	applyLocaleToService(svc, ctx.Locale)
 	return ctx
 }
+
+// context.go: SetLocale updates the context locale and reapplies it to the active translator.
+// Example: ctx.SetLocale("en-US").
+func (ctx *Context) SetLocale(locale string) *Context {
+	if ctx == nil {
+		return nil
+	}
+
+	ensureContextDefaults(ctx)
+	ctx.Locale = locale
+	applyLocaleToService(ctx.service, ctx.Locale)
+	return ctx
+}

context_test.go

@@ -48,3 +48,34 @@ func TestContext_NewContextWithService_UsesLocale(t *testing.T) {
 		t.Fatalf("NewContextWithService translation = %q, want %q", got, "y")
 	}
 }
+
+func TestContext_SetLocale_ReappliesTranslatorLanguage(t *testing.T) {
+	svc := &localeTranslator{}
+	ctx := NewContextWithService(svc, "en-GB")
+
+	ctx.SetLocale("fr-FR")
+
+	if ctx.Locale != "fr-FR" {
+		t.Fatalf("SetLocale() Locale = %q, want %q", ctx.Locale, "fr-FR")
+	}
+	if svc.language != "fr" {
+		t.Fatalf("SetLocale() should reapply language to translator, got %q", svc.language)
+	}
+	if got := Text("prompt.yes").Render(ctx); got != "o" {
+		t.Fatalf("SetLocale() translation = %q, want %q", got, "o")
+	}
+}
+
+func TestContext_SetService_AppliesCurrentLocale(t *testing.T) {
+	svc := &localeTranslator{}
+	ctx := NewContext("fr-FR")
+
+	ctx.SetService(svc)
+
+	if ctx.service != svc {
+		t.Fatal("SetService() should retain the provided service")
+	}
+	if svc.language != "fr" {
+		t.Fatalf("SetService() should apply current locale to translator, got %q", svc.language)
+	}
+}

docs/development.md

@@ -299,6 +299,6 @@ func TestGenerateClass_Good(t *testing.T) {
 
 - `NewLayout("XYZ")` silently produces empty output for unrecognised slot letters. Valid letters are `H`, `L`, `C`, `R`, `F`. There is no error or warning.
 - `Responsive.Variant()` accepts only `*Layout`, not arbitrary `Node` values. Arbitrary subtrees must be wrapped in a single-slot layout first.
-- `Context.service` is unexported. Custom i18n service injection requires `NewContextWithService()`. There is no way to swap the service after construction.
+- `Context.service` is unexported. Custom i18n service injection uses `NewContextWithService()` or `SetService()`, and `SetLocale()` reapplies the active locale to the current translator.
 - The WASM module has no integration test for the JavaScript exports. `size_test.go` tests binary size only; it does not exercise `renderToString` behaviour from JavaScript.
 - `codegen.GenerateBundle()` iterates a `map`, so the order of class definitions in the output is non-deterministic. This does not affect correctness but may cause cosmetic diffs between runs.