diff --git a/install/i18n/ar.sh b/install/i18n/ar.sh
new file mode 100644
index 0000000..c11b692
--- /dev/null
+++ b/install/i18n/ar.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/ar.sh — العربية.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="معالج الإعداد الأولي (5 خطوات)"
+STR_PICK_LANGUAGE="اختر لغة الواجهة:"
+STR_PICK_TRANSPORT="اختر طريقة الاتصال:"
+STR_PICK_PROVIDER="اختر المزود ضمن المجموعة"
+STR_PICK_MODEL="النموذج الافتراضي:"
+
+STR_TR_DIRECT_API="واجهة برمجية مباشرة للمزود (مفتاح)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/دور)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+مفتاح)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="محلي (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="وكيل (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="اشتراك OAuth (ChatGPT)"
+
+STR_AUTH_INTRO="المصادقة لـ"
+STR_AUTH_PROMPT="أدخل القيم (Enter — اتركها فارغة، املأها لاحقًا)."
+STR_AUTH_CURRENT_HINT="(الحالي: <مخفي>)"
+
+STR_DONE_TITLE="اكتمل الإعداد الأولي"
+STR_DONE_CONFIG="التكوين:"
+STR_DONE_SECRETS="الأسرار:"
+
+STR_MENU_TITLE="مثبّت KeiSeiKit"
+STR_MENU_SUBSTRATE="القاعدة الأساسية (دائمًا مثبتة):"
+STR_MENU_PROFILE_PROMPT="اختر ملف التثبيت:"
+STR_MENU_CONFIRM="تأكيد الاختيار؟"
+
+STR_PREFLIGHT_FAILED="فشل Preflight — قد لا يعمل المزود."
+STR_PREFLIGHT_CONTINUE="هل تريد المتابعة على أي حال؟ [y/N]"
diff --git a/install/i18n/de.sh b/install/i18n/de.sh
new file mode 100644
index 0000000..e656640
--- /dev/null
+++ b/install/i18n/de.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/de.sh — Deutsch.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="Einrichtungsassistent (5 Schritte)"
+STR_PICK_LANGUAGE="Oberflächensprache wählen:"
+STR_PICK_TRANSPORT="Verbindungsart wählen:"
+STR_PICK_PROVIDER="Anbieter in der Gruppe wählen"
+STR_PICK_MODEL="Standardmodell:"
+
+STR_TR_DIRECT_API="Direkte API des Anbieters (Schlüssel)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/Rolle)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (Deployment+Schlüssel)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="Lokal (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="Proxy (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="OAuth-Abo (ChatGPT)"
+
+STR_AUTH_INTRO="Authentifizierung für"
+STR_AUTH_PROMPT="Werte eingeben (Enter — leer lassen, später ausfüllen)."
+STR_AUTH_CURRENT_HINT="(aktuell: <ausgeblendet>)"
+
+STR_DONE_TITLE="Einrichtung abgeschlossen"
+STR_DONE_CONFIG="Konfig:"
+STR_DONE_SECRETS="Geheimnisse:"
+
+STR_MENU_TITLE="KeiSeiKit Installer"
+STR_MENU_SUBSTRATE="Substrat-Basis (immer installiert):"
+STR_MENU_PROFILE_PROMPT="Installationsprofil wählen:"
+STR_MENU_CONFIRM="Auswahl bestätigen?"
+
+STR_PREFLIGHT_FAILED="Preflight fehlgeschlagen — Anbieter funktioniert evtl. nicht."
+STR_PREFLIGHT_CONTINUE="Trotzdem fortfahren? [j/N]"
diff --git a/install/i18n/es.sh b/install/i18n/es.sh
new file mode 100644
index 0000000..e56e91d
--- /dev/null
+++ b/install/i18n/es.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/es.sh — Español.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="Asistente de configuración inicial (5 pasos)"
+STR_PICK_LANGUAGE="Elige el idioma de la interfaz:"
+STR_PICK_TRANSPORT="Elige el método de conexión:"
+STR_PICK_PROVIDER="Elige el proveedor dentro de"
+STR_PICK_MODEL="Modelo por defecto:"
+
+STR_TR_DIRECT_API="API directa del proveedor (clave)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/rol)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+clave)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="Local (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="Proxy (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="Suscripción OAuth (ChatGPT)"
+
+STR_AUTH_INTRO="Autenticación para"
+STR_AUTH_PROMPT="Introduce los valores (Enter — dejar vacío, completar luego)."
+STR_AUTH_CURRENT_HINT="(actual: <oculto>)"
+
+STR_DONE_TITLE="Configuración inicial completada"
+STR_DONE_CONFIG="config:"
+STR_DONE_SECRETS="secretos:"
+
+STR_MENU_TITLE="Instalador de KeiSeiKit"
+STR_MENU_SUBSTRATE="Base del sustrato (siempre instalada):"
+STR_MENU_PROFILE_PROMPT="Elige el perfil de instalación:"
+STR_MENU_CONFIRM="¿Confirmar selección?"
+
+STR_PREFLIGHT_FAILED="Preflight falló — el proveedor puede no funcionar."
+STR_PREFLIGHT_CONTINUE="¿Continuar de todos modos? [s/N]"
diff --git a/install/i18n/fr.sh b/install/i18n/fr.sh
new file mode 100644
index 0000000..6fe09ee
--- /dev/null
+++ b/install/i18n/fr.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/fr.sh — Français.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="Assistant de configuration initiale (5 étapes)"
+STR_PICK_LANGUAGE="Choisir la langue de l'interface :"
+STR_PICK_TRANSPORT="Choisir le mode de connexion :"
+STR_PICK_PROVIDER="Choisir le fournisseur dans le groupe"
+STR_PICK_MODEL="Modèle par défaut :"
+
+STR_TR_DIRECT_API="API directe du fournisseur (clé)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/rôle)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+clé)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="Local (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="Proxy (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="Abonnement OAuth (ChatGPT)"
+
+STR_AUTH_INTRO="Authentification pour"
+STR_AUTH_PROMPT="Saisir les valeurs (Entrée — laisser vide, remplir plus tard)."
+STR_AUTH_CURRENT_HINT="(actuel : <masqué>)"
+
+STR_DONE_TITLE="Configuration initiale terminée"
+STR_DONE_CONFIG="config :"
+STR_DONE_SECRETS="secrets :"
+
+STR_MENU_TITLE="Installateur KeiSeiKit"
+STR_MENU_SUBSTRATE="Base du substrat (toujours installée) :"
+STR_MENU_PROFILE_PROMPT="Choisir le profil d'installation :"
+STR_MENU_CONFIRM="Confirmer la sélection ?"
+
+STR_PREFLIGHT_FAILED="Preflight échoué — le fournisseur peut ne pas fonctionner."
+STR_PREFLIGHT_CONTINUE="Continuer quand même ? [o/N]"
diff --git a/install/i18n/hi.sh b/install/i18n/hi.sh
new file mode 100644
index 0000000..7e28f22
--- /dev/null
+++ b/install/i18n/hi.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/hi.sh — हिन्दी.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="प्रारंभिक सेटअप विज़ार्ड (5 चरण)"
+STR_PICK_LANGUAGE="इंटरफ़ेस भाषा चुनें:"
+STR_PICK_TRANSPORT="कनेक्शन विधि चुनें:"
+STR_PICK_PROVIDER="समूह में प्रदाता चुनें"
+STR_PICK_MODEL="डिफ़ॉल्ट मॉडल:"
+
+STR_TR_DIRECT_API="प्रदाता डायरेक्ट API (कुंजी)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/रोल)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+कुंजी)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="लोकल (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="प्रॉक्सी (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="OAuth सब्सक्रिप्शन (ChatGPT)"
+
+STR_AUTH_INTRO="के लिए प्रमाणीकरण"
+STR_AUTH_PROMPT="मान दर्ज करें (Enter — खाली छोड़ें, बाद में भरें)।"
+STR_AUTH_CURRENT_HINT="(वर्तमान: <छिपा हुआ>)"
+
+STR_DONE_TITLE="प्रारंभिक सेटअप पूरा हुआ"
+STR_DONE_CONFIG="कॉन्फ़िग:"
+STR_DONE_SECRETS="सीक्रेट्स:"
+
+STR_MENU_TITLE="KeiSeiKit इंस्टॉलर"
+STR_MENU_SUBSTRATE="सब्सट्रेट बेस (हमेशा स्थापित):"
+STR_MENU_PROFILE_PROMPT="इंस्टॉल प्रोफ़ाइल चुनें:"
+STR_MENU_CONFIRM="चयन की पुष्टि करें?"
+
+STR_PREFLIGHT_FAILED="Preflight विफल — प्रदाता काम नहीं कर सकता।"
+STR_PREFLIGHT_CONTINUE="फिर भी जारी रखें? [y/N]"
diff --git a/install/i18n/id.sh b/install/i18n/id.sh
new file mode 100644
index 0000000..38ba59e
--- /dev/null
+++ b/install/i18n/id.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/id.sh — Bahasa Indonesia.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="Wizard pengaturan awal (5 langkah)"
+STR_PICK_LANGUAGE="Pilih bahasa antarmuka:"
+STR_PICK_TRANSPORT="Pilih metode koneksi:"
+STR_PICK_PROVIDER="Pilih penyedia dalam grup"
+STR_PICK_MODEL="Model default:"
+
+STR_TR_DIRECT_API="API langsung penyedia (kunci)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/role)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+kunci)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="Lokal (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="Proxy (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="Langganan OAuth (ChatGPT)"
+
+STR_AUTH_INTRO="Autentikasi untuk"
+STR_AUTH_PROMPT="Masukkan nilai (Enter — kosongkan, isi nanti)."
+STR_AUTH_CURRENT_HINT="(saat ini: <tersembunyi>)"
+
+STR_DONE_TITLE="Pengaturan awal selesai"
+STR_DONE_CONFIG="konfig:"
+STR_DONE_SECRETS="rahasia:"
+
+STR_MENU_TITLE="Installer KeiSeiKit"
+STR_MENU_SUBSTRATE="Basis substrat (selalu terpasang):"
+STR_MENU_PROFILE_PROMPT="Pilih profil instalasi:"
+STR_MENU_CONFIRM="Konfirmasi pilihan?"
+
+STR_PREFLIGHT_FAILED="Preflight gagal — penyedia mungkin tidak berfungsi."
+STR_PREFLIGHT_CONTINUE="Lanjutkan saja? [y/N]"
diff --git a/install/i18n/it.sh b/install/i18n/it.sh
new file mode 100644
index 0000000..6884986
--- /dev/null
+++ b/install/i18n/it.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/it.sh — Italiano.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="Procedura guidata di configurazione iniziale (5 passi)"
+STR_PICK_LANGUAGE="Scegli la lingua dell'interfaccia:"
+STR_PICK_TRANSPORT="Scegli il metodo di connessione:"
+STR_PICK_PROVIDER="Scegli il provider nel gruppo"
+STR_PICK_MODEL="Modello predefinito:"
+
+STR_TR_DIRECT_API="API diretta del provider (chiave)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/ruolo)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+chiave)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="Locale (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="Proxy (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="Abbonamento OAuth (ChatGPT)"
+
+STR_AUTH_INTRO="Autenticazione per"
+STR_AUTH_PROMPT="Inserisci i valori (Invio — lascia vuoto, compila dopo)."
+STR_AUTH_CURRENT_HINT="(attuale: <nascosto>)"
+
+STR_DONE_TITLE="Configurazione iniziale completata"
+STR_DONE_CONFIG="config:"
+STR_DONE_SECRETS="segreti:"
+
+STR_MENU_TITLE="Installatore KeiSeiKit"
+STR_MENU_SUBSTRATE="Base del substrato (sempre installata):"
+STR_MENU_PROFILE_PROMPT="Scegli il profilo di installazione:"
+STR_MENU_CONFIRM="Confermare la selezione?"
+
+STR_PREFLIGHT_FAILED="Preflight fallito — il provider potrebbe non funzionare."
+STR_PREFLIGHT_CONTINUE="Continuare comunque? [s/N]"
diff --git a/install/i18n/ja.sh b/install/i18n/ja.sh
new file mode 100644
index 0000000..9d5bceb
--- /dev/null
+++ b/install/i18n/ja.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/ja.sh — 日本語.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="初期設定ウィザード (5 ステップ)"
+STR_PICK_LANGUAGE="インターフェース言語を選択:"
+STR_PICK_TRANSPORT="接続方法を選択:"
+STR_PICK_PROVIDER="グループ内のプロバイダを選択"
+STR_PICK_MODEL="デフォルトモデル:"
+
+STR_TR_DIRECT_API="プロバイダ直接 API (キー)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/ロール)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+キー)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="ローカル (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="プロキシ (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="OAuth サブスクリプション (ChatGPT)"
+
+STR_AUTH_INTRO="認証 —"
+STR_AUTH_PROMPT="値を入力 (Enter — 空のまま、後で記入)。"
+STR_AUTH_CURRENT_HINT="(現在: <非表示>)"
+
+STR_DONE_TITLE="初期設定が完了しました"
+STR_DONE_CONFIG="設定:"
+STR_DONE_SECRETS="シークレット:"
+
+STR_MENU_TITLE="KeiSeiKit インストーラ"
+STR_MENU_SUBSTRATE="サブストレートのベース (常にインストール):"
+STR_MENU_PROFILE_PROMPT="インストールプロファイルを選択:"
+STR_MENU_CONFIRM="選択を確認しますか?"
+
+STR_PREFLIGHT_FAILED="Preflight 失敗 — プロバイダが動作しない可能性があります。"
+STR_PREFLIGHT_CONTINUE="それでも続行しますか? [y/N]"
diff --git a/install/i18n/ko.sh b/install/i18n/ko.sh
new file mode 100644
index 0000000..7c20972
--- /dev/null
+++ b/install/i18n/ko.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/ko.sh — 한국어.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="초기 설정 마법사 (5 단계)"
+STR_PICK_LANGUAGE="인터페이스 언어 선택:"
+STR_PICK_TRANSPORT="연결 방법 선택:"
+STR_PICK_PROVIDER="그룹 내 제공자 선택"
+STR_PICK_MODEL="기본 모델:"
+
+STR_TR_DIRECT_API="제공자 직접 API (키)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/역할)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+키)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="로컬 (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="프록시 (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="OAuth 구독 (ChatGPT)"
+
+STR_AUTH_INTRO="인증 —"
+STR_AUTH_PROMPT="값을 입력하세요 (Enter — 비워두고 나중에 작성)."
+STR_AUTH_CURRENT_HINT="(현재: <숨김>)"
+
+STR_DONE_TITLE="초기 설정 완료"
+STR_DONE_CONFIG="설정:"
+STR_DONE_SECRETS="시크릿:"
+
+STR_MENU_TITLE="KeiSeiKit 설치 프로그램"
+STR_MENU_SUBSTRATE="기본 서브스트레이트 (항상 설치):"
+STR_MENU_PROFILE_PROMPT="설치 프로필 선택:"
+STR_MENU_CONFIRM="선택을 확인하시겠습니까?"
+
+STR_PREFLIGHT_FAILED="Preflight 실패 — 제공자가 작동하지 않을 수 있습니다."
+STR_PREFLIGHT_CONTINUE="계속 진행하시겠습니까? [y/N]"
diff --git a/install/i18n/pt.sh b/install/i18n/pt.sh
new file mode 100644
index 0000000..fb4bcf0
--- /dev/null
+++ b/install/i18n/pt.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/pt.sh — Português.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="Assistente de configuração inicial (5 passos)"
+STR_PICK_LANGUAGE="Escolha o idioma da interface:"
+STR_PICK_TRANSPORT="Escolha o método de conexão:"
+STR_PICK_PROVIDER="Escolha o provedor dentro do grupo"
+STR_PICK_MODEL="Modelo padrão:"
+
+STR_TR_DIRECT_API="API direta do provedor (chave)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/função)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+chave)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="Local (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="Proxy (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="Assinatura OAuth (ChatGPT)"
+
+STR_AUTH_INTRO="Autenticação para"
+STR_AUTH_PROMPT="Insira valores (Enter — deixar vazio, preencher depois)."
+STR_AUTH_CURRENT_HINT="(atual: <oculto>)"
+
+STR_DONE_TITLE="Configuração inicial concluída"
+STR_DONE_CONFIG="config:"
+STR_DONE_SECRETS="segredos:"
+
+STR_MENU_TITLE="Instalador KeiSeiKit"
+STR_MENU_SUBSTRATE="Base do substrato (sempre instalada):"
+STR_MENU_PROFILE_PROMPT="Escolha o perfil de instalação:"
+STR_MENU_CONFIRM="Confirmar seleção?"
+
+STR_PREFLIGHT_FAILED="Preflight falhou — o provedor pode não funcionar."
+STR_PREFLIGHT_CONTINUE="Continuar mesmo assim? [s/N]"
diff --git a/install/i18n/tr.sh b/install/i18n/tr.sh
new file mode 100644
index 0000000..2bff611
--- /dev/null
+++ b/install/i18n/tr.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/tr.sh — Türkçe.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="İlk kurulum sihirbazı (5 adım)"
+STR_PICK_LANGUAGE="Arayüz dilini seçin:"
+STR_PICK_TRANSPORT="Bağlantı yöntemini seçin:"
+STR_PICK_PROVIDER="Gruptaki sağlayıcıyı seçin"
+STR_PICK_MODEL="Varsayılan model:"
+
+STR_TR_DIRECT_API="Sağlayıcının doğrudan API'si (anahtar)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/rol)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+anahtar)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="Yerel (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="Proxy (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="OAuth aboneliği (ChatGPT)"
+
+STR_AUTH_INTRO="Kimlik doğrulama —"
+STR_AUTH_PROMPT="Değerleri girin (Enter — boş bırak, sonra doldur)."
+STR_AUTH_CURRENT_HINT="(geçerli: <gizli>)"
+
+STR_DONE_TITLE="İlk kurulum tamamlandı"
+STR_DONE_CONFIG="yapılandırma:"
+STR_DONE_SECRETS="gizli anahtarlar:"
+
+STR_MENU_TITLE="KeiSeiKit Kurulum Aracı"
+STR_MENU_SUBSTRATE="Substrate tabanı (her zaman kurulu):"
+STR_MENU_PROFILE_PROMPT="Kurulum profilini seçin:"
+STR_MENU_CONFIRM="Seçimi onayla?"
+
+STR_PREFLIGHT_FAILED="Preflight başarısız — sağlayıcı çalışmayabilir."
+STR_PREFLIGHT_CONTINUE="Yine de devam edilsin mi? [e/H]"
diff --git a/install/i18n/uk.sh b/install/i18n/uk.sh
new file mode 100644
index 0000000..e594243
--- /dev/null
+++ b/install/i18n/uk.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/uk.sh — Українська.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="Майстер первинного налаштування (5 кроків)"
+STR_PICK_LANGUAGE="Виберіть мову інтерфейсу:"
+STR_PICK_TRANSPORT="Виберіть спосіб підключення:"
+STR_PICK_PROVIDER="Виберіть провайдера у групі"
+STR_PICK_MODEL="Модель за замовчуванням:"
+
+STR_TR_DIRECT_API="Прямий API провайдера (ключ)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/роль)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+ключ)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="Локально (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="Проксі (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="OAuth-підписка (ChatGPT)"
+
+STR_AUTH_INTRO="Автентифікація для"
+STR_AUTH_PROMPT="Введіть значення (Enter — залишити порожнім, заповнити пізніше)."
+STR_AUTH_CURRENT_HINT="(поточне: <приховано>)"
+
+STR_DONE_TITLE="Первинне налаштування завершено"
+STR_DONE_CONFIG="конфіг:"
+STR_DONE_SECRETS="секрети:"
+
+STR_MENU_TITLE="Інсталятор KeiSeiKit"
+STR_MENU_SUBSTRATE="База підкладки (завжди встановлюється):"
+STR_MENU_PROFILE_PROMPT="Виберіть профіль встановлення:"
+STR_MENU_CONFIRM="Підтвердити вибір?"
+
+STR_PREFLIGHT_FAILED="Preflight упав — провайдер може не працювати."
+STR_PREFLIGHT_CONTINUE="Продовжити все одно? [y/N]"
diff --git a/install/i18n/vi.sh b/install/i18n/vi.sh
new file mode 100644
index 0000000..89005b3
--- /dev/null
+++ b/install/i18n/vi.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/vi.sh — Tiếng Việt.
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="Trình hướng dẫn thiết lập ban đầu (5 bước)"
+STR_PICK_LANGUAGE="Chọn ngôn ngữ giao diện:"
+STR_PICK_TRANSPORT="Chọn phương thức kết nối:"
+STR_PICK_PROVIDER="Chọn nhà cung cấp trong nhóm"
+STR_PICK_MODEL="Mô hình mặc định:"
+
+STR_TR_DIRECT_API="API trực tiếp của nhà cung cấp (khóa)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/vai trò)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (deployment+khóa)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="Cục bộ (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="Proxy (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="Đăng ký OAuth (ChatGPT)"
+
+STR_AUTH_INTRO="Xác thực cho"
+STR_AUTH_PROMPT="Nhập giá trị (Enter — để trống, điền sau)."
+STR_AUTH_CURRENT_HINT="(hiện tại: <đã ẩn>)"
+
+STR_DONE_TITLE="Thiết lập ban đầu hoàn tất"
+STR_DONE_CONFIG="cấu hình:"
+STR_DONE_SECRETS="bí mật:"
+
+STR_MENU_TITLE="Trình cài đặt KeiSeiKit"
+STR_MENU_SUBSTRATE="Nền tảng substrate (luôn cài đặt):"
+STR_MENU_PROFILE_PROMPT="Chọn hồ sơ cài đặt:"
+STR_MENU_CONFIRM="Xác nhận lựa chọn?"
+
+STR_PREFLIGHT_FAILED="Preflight thất bại — nhà cung cấp có thể không hoạt động."
+STR_PREFLIGHT_CONTINUE="Vẫn tiếp tục? [y/N]"
diff --git a/install/i18n/zh.sh b/install/i18n/zh.sh
new file mode 100644
index 0000000..303dee0
--- /dev/null
+++ b/install/i18n/zh.sh
@@ -0,0 +1,35 @@
+# shellcheck shell=bash
+# i18n/zh.sh — 简体中文 (Simplified Chinese).
+
+STR_WELCOME_TITLE="KeiSeiKit · Exobrain installer"
+STR_WELCOME_TAGLINE="Portable Rust agent substrate for AI coding tools"
+
+STR_ONBOARDING_INTRO="初始化向导 (5 步)"
+STR_PICK_LANGUAGE="选择界面语言:"
+STR_PICK_TRANSPORT="选择连接方式:"
+STR_PICK_PROVIDER="选择此分组中的提供者"
+STR_PICK_MODEL="默认模型:"
+
+STR_TR_DIRECT_API="提供者直连 API (密钥)"
+STR_TR_AWS_BEDROCK="AWS Bedrock (IAM/角色)"
+STR_TR_AZURE_OPENAI="Azure OpenAI (部署 + 密钥)"
+STR_TR_GOOGLE_VERTEX="Google Vertex AI (GCP)"
+STR_TR_LOCAL="本地 (Ollama/MLX/LMStudio)"
+STR_TR_PROXY="代理 (LiteLLM/OpenRouter)"
+STR_TR_SUBSCRIPTION="OAuth 订阅 (ChatGPT)"
+
+STR_AUTH_INTRO="认证"
+STR_AUTH_PROMPT="输入值 (回车 — 保留为空,稍后填写)。"
+STR_AUTH_CURRENT_HINT="(当前: <已隐藏>)"
+
+STR_DONE_TITLE="初始化完成"
+STR_DONE_CONFIG="配置:"
+STR_DONE_SECRETS="密钥:"
+
+STR_MENU_TITLE="KeiSeiKit 安装器"
+STR_MENU_SUBSTRATE="基础组件 (始终安装):"
+STR_MENU_PROFILE_PROMPT="选择安装配置:"
+STR_MENU_CONFIRM="确认选择?"
+
+STR_PREFLIGHT_FAILED="Preflight 失败 — 提供者可能无法工作。"
+STR_PREFLIGHT_CONTINUE="仍然继续? [y/N]"
diff --git a/install/lib-i18n.sh b/install/lib-i18n.sh
index 3ce29fe..ad6c96e 100644
--- a/install/lib-i18n.sh
+++ b/install/lib-i18n.sh
@@ -21,19 +21,37 @@ i18n_load_default() {
 
 i18n_load_lang() {
   local lang="$1"
-  case "$lang" in
-    en)
-      i18n_load_default
-      ;;
-    ru)
-      i18n_load_default                       # base (fallback values)
-      # shellcheck source=install/i18n/ru.sh
-      [ -f "$I18N_DIR/ru.sh" ] && source "$I18N_DIR/ru.sh"
-      ;;
-    *)
-      i18n_load_default
-      ;;
-  esac
+  # Сначала всегда грузим английский — это база fallback.
+  i18n_load_default
+  # Если выбран не-английский — поверх кладём словарь языка.
+  # Любой STR_*, отсутствующий в файле, остаётся с английским значением.
+  if [ "$lang" != "en" ] && [ -f "$I18N_DIR/${lang}.sh" ]; then
+    # shellcheck disable=SC1090
+    source "$I18N_DIR/${lang}.sh"
+  fi
+}
+
+# Список доступных языков — для onboarding_pick_language.
+# Формат: <code>\t<display_name>
+i18n_available_languages() {
+  cat <<'EOF'
+en	English
+ru	Русский
+uk	Українська
+de	Deutsch
+fr	Français
+es	Español
+pt	Português
+it	Italiano
+tr	Türkçe
+ar	العربية
+hi	हिन्दी
+zh	简体中文
+ja	日本語
+ko	한국어
+id	Bahasa Indonesia
+vi	Tiếng Việt
+EOF
 }
 
 # Welcome banner. Всегда EN. Запускается из install.sh до мастера.
diff --git a/install/lib-onboarding.sh b/install/lib-onboarding.sh
index e724860..e92be51 100644
--- a/install/lib-onboarding.sh
+++ b/install/lib-onboarding.sh
@@ -108,23 +108,42 @@ onboarding_models_for_provider() {
 # UI: язык
 # ───────────────────────────────────────────────────────────────────────
 onboarding_pick_language() {
-  # На этом шаге язык ещё не выбран — экран на двух языках одновременно.
+  # Список языков читается из lib-i18n.sh::i18n_available_languages.
+  # На этом шаге язык ещё не выбран — заголовок двуязычный.
+  local langs
+  langs="$(i18n_available_languages 2>/dev/null)"
+  if [ -z "$langs" ]; then
+    # Fallback если lib-i18n не подключён.
+    langs="$(printf 'en\tEnglish\nru\tРусский\n')"
+  fi
+
   if command -v whiptail >/dev/null 2>&1; then
-    ONBOARDING_LANG=$(whiptail --title "KeiSei · Language / Язык" --radiolist \
-      "Choose interface language / Выберите язык:" 12 60 2 \
-      "en" "English" ON \
-      "ru" "Русский" OFF \
-      3>&1 1>&2 2>&3) || ONBOARDING_LANG="en"
+    local args=() first=1
+    while IFS=$'\t' read -r code name; do
+      [ -z "$code" ] && continue
+      if [ "$first" = "1" ]; then
+        args+=("$code" "$name" "ON"); first=0
+      else
+        args+=("$code" "$name" "OFF")
+      fi
+    done <<< "$langs"
+    ONBOARDING_LANG=$(whiptail --title "KeiSei · Language / Язык / 语言 / 言語 / ..." --radiolist \
+      "Choose interface language / Выберите язык:" 22 70 16 \
+      "${args[@]}" 3>&1 1>&2 2>&3) || ONBOARDING_LANG="en"
   else
     echo "" >&2
-    echo "Choose language / Выберите язык:" >&2
-    echo "  1) en — English (default)" >&2
-    echo "  2) ru — Русский" >&2
-    read -r -p "[1-2, default 1]: " ans
-    case "$ans" in
-      2) ONBOARDING_LANG="ru" ;;
-      *) ONBOARDING_LANG="en" ;;
-    esac
+    echo "Choose language / Выберите язык / 选择语言 / 言語選択:" >&2
+    declare -a codes=()
+    local i=1
+    while IFS=$'\t' read -r code name; do
+      [ -z "$code" ] && continue
+      codes+=("$code")
+      printf "  %2d) %s — %s\n" "$i" "$code" "$name" >&2
+      i=$((i+1))
+    done <<< "$langs"
+    read -r -p "[1-${#codes[@]}, default 1=en]: " ans
+    ans="${ans:-1}"
+    ONBOARDING_LANG="${codes[$((ans-1))]:-en}"
   fi
   # Перегружаем словарь — все последующие строки на выбранном языке.
   if command -v i18n_load_lang >/dev/null 2>&1; then