From 02339893ee80a448844bef89f03db6e16c852653 Mon Sep 17 00:00:00 2001
From: Virgil <virgil@lethean.io>
Date: Thu, 2 Apr 2026 09:40:20 +0000
Subject: [PATCH] feat(i18n): add handler chain replacement helpers

Co-Authored-By: Virgil <virgil@lethean.io>
---
 i18n.go         | 15 +++++++++++++++
 i18n_test.go    | 19 +++++++++++++++++++
 service.go      |  7 +++++++
 service_test.go | 19 +++++++++++++++++++
 4 files changed, 60 insertions(+)

diff --git a/i18n.go b/i18n.go
index 4173ca6..576827a 100644
--- a/i18n.go
+++ b/i18n.go
@@ -172,6 +172,13 @@ func AddHandler(handlers ...KeyHandler) {
 	}
 }
 
+// SetHandlers replaces the default service's handler chain.
+func SetHandlers(handlers ...KeyHandler) {
+	if svc := Default(); svc != nil {
+		svc.SetHandlers(handlers...)
+	}
+}
+
 // LoadFS loads additional translations from an fs.FS into the default service.
 //
 // Call this from init() in packages that ship their own locale files:
@@ -195,6 +202,14 @@ func PrependHandler(handlers ...KeyHandler) {
 	}
 }
 
+// CurrentHandlers returns a copy of the default service's handler chain.
+func CurrentHandlers() []KeyHandler {
+	if svc := Default(); svc != nil {
+		return svc.Handlers()
+	}
+	return nil
+}
+
 // ClearHandlers removes all handlers from the default service.
 func ClearHandlers() {
 	if svc := Default(); svc != nil {
diff --git a/i18n_test.go b/i18n_test.go
index c3c91bf..b12bd8d 100644
--- a/i18n_test.go
+++ b/i18n_test.go
@@ -401,6 +401,25 @@ func TestClearHandlers_Good(t *testing.T) {
 	assert.Empty(t, svc.Handlers())
 }
 
+func TestSetHandlers_Good(t *testing.T) {
+	svc, err := New()
+	require.NoError(t, err)
+	_ = Init()
+	prev := Default()
+	SetDefault(svc)
+	t.Cleanup(func() {
+		SetDefault(prev)
+	})
+
+	SetHandlers(serviceStubHandler{})
+
+	handlers := CurrentHandlers()
+	require.Len(t, handlers, 1)
+	assert.IsType(t, serviceStubHandler{}, handlers[0])
+	assert.Equal(t, "stub", T("custom.stub"))
+	assert.Equal(t, "i18n.label.status", T("i18n.label.status"))
+}
+
 func TestNewWithHandlers_SkipsNil(t *testing.T) {
 	svc, err := New(WithHandlers(nil, LabelHandler{}))
 	require.NoError(t, err)
diff --git a/service.go b/service.go
index 1109dba..0568635 100644
--- a/service.go
+++ b/service.go
@@ -406,6 +406,13 @@ func (s *Service) AddHandler(handlers ...KeyHandler) {
 	s.handlers = append(s.handlers, filterNilHandlers(handlers)...)
 }
 
+// SetHandlers replaces the current handler chain.
+func (s *Service) SetHandlers(handlers ...KeyHandler) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.handlers = filterNilHandlers(handlers)
+}
+
 func (s *Service) PrependHandler(handlers ...KeyHandler) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
diff --git a/service_test.go b/service_test.go
index d697123..44bae7a 100644
--- a/service_test.go
+++ b/service_test.go
@@ -1034,6 +1034,25 @@ func TestServiceHandlers(t *testing.T) {
 	}
 }
 
+func TestServiceSetHandlers(t *testing.T) {
+	svc, err := New()
+	if err != nil {
+		t.Fatalf("New() failed: %v", err)
+	}
+
+	svc.SetHandlers(serviceStubHandler{}, nil, LabelHandler{})
+	handlers := svc.Handlers()
+	if got, want := len(handlers), 2; got != want {
+		t.Fatalf("len(Handlers()) = %d, want %d", got, want)
+	}
+	if _, ok := handlers[0].(serviceStubHandler); !ok {
+		t.Fatalf("Handlers()[0] = %T, want serviceStubHandler", handlers[0])
+	}
+	if _, ok := handlers[1].(LabelHandler); !ok {
+		t.Fatalf("Handlers()[1] = %T, want LabelHandler", handlers[1])
+	}
+}
+
 func TestWithDefaultHandlers_Idempotent(t *testing.T) {
 	svc, err := New(WithDefaultHandlers())
 	if err != nil {
-- 
2.45.3