From 87557b66e419477d663a4171f2aa5fa0f9011825 Mon Sep 17 00:00:00 2001
From: Virgil <virgil@lethean.io>
Date: Wed, 1 Apr 2026 08:17:37 +0000
Subject: [PATCH] feat(i18n): load registered locales during init

Co-Authored-By: Virgil <virgil@lethean.io>
---
 hooks_test.go | 38 ++++++++++++++++++++++++++++++++++++++
 service.go    |  8 +++++++-
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/hooks_test.go b/hooks_test.go
index d6c78b0..7727fb6 100644
--- a/hooks_test.go
+++ b/hooks_test.go
@@ -1,6 +1,7 @@
 package i18n
 
 import (
+	"sync"
 	"testing"
 	"testing/fstest"
 
@@ -72,6 +73,43 @@ func TestRegisterLocales_Good_AfterLocalesLoaded(t *testing.T) {
 	assert.Equal(t, "arrived late", got)
 }
 
+func TestInit_LoadsRegisteredLocales(t *testing.T) {
+	// Save and restore global service state.
+	registeredLocalesMu.Lock()
+	savedLocales := registeredLocales
+	savedLoaded := localesLoaded
+	registeredLocales = nil
+	localesLoaded = false
+	registeredLocalesMu.Unlock()
+
+	defaultOnce = sync.Once{}
+	defaultService.Store(nil)
+
+	defer func() {
+		registeredLocalesMu.Lock()
+		registeredLocales = savedLocales
+		localesLoaded = savedLoaded
+		registeredLocalesMu.Unlock()
+		defaultService.Store(nil)
+		defaultOnce = sync.Once{}
+	}()
+
+	fs := fstest.MapFS{
+		"locales/en.json": &fstest.MapFile{
+			Data: []byte(`{"init.registered": "loaded on init"}`),
+		},
+	}
+	RegisterLocales(fs, "locales")
+
+	require.NoError(t, Init())
+
+	svc := Default()
+	require.NotNil(t, svc)
+
+	got := svc.T("init.registered")
+	assert.Equal(t, "loaded on init", got)
+}
+
 func TestLoadRegisteredLocales_Good(t *testing.T) {
 	svc, err := New()
 	require.NoError(t, err)
diff --git a/service.go b/service.go
index b06714a..20a33bd 100644
--- a/service.go
+++ b/service.go
@@ -136,9 +136,15 @@ func Init() error {
 		}
 		svc, err := New()
 		if err == nil {
+			// Register and load any locales queued before initialisation.
+			loadRegisteredLocales(svc)
 			// CAS prevents overwriting a concurrent SetDefault call that
 			// raced between the Load check above and this store.
-			defaultService.CompareAndSwap(nil, svc)
+			if !defaultService.CompareAndSwap(nil, svc) {
+				// If a concurrent caller already installed a service, load
+				// registered locales into that active default service instead.
+				loadRegisteredLocales(defaultService.Load())
+			}
 		}
 		defaultErr = err
 	})
-- 
2.45.3