diff --git a/app/main_gtk.py b/app/main_gtk.py
index d8ff38c..585eb53 100644
--- a/app/main_gtk.py
+++ b/app/main_gtk.py
@@ -61,6 +61,30 @@ def _build_pipeline_config(config: AppConfig) -> PipelineConfig:
     )
 
 
+def _guess_locale_lang() -> str:
+    """Tries to find the user's locale from the OS.
+
+    Falls back to RU if the locale can't be read
+    or doesn't map to a supported language.
+    """
+    import locale
+
+    for env_var in ("LC_ALL", "LC_MESSAGES", "LANG", "LANGUAGE"):
+        val = os.environ.get(env_var, "")
+        if val:
+            code = val.split(".")[0].split("_")[0].upper()
+            if code in ("RU", "EN", "ES"):
+                return code
+    try:
+        loc = locale.getlocale()[0] or ""
+        code = loc.split("_")[0].upper()
+        if code in ("RU", "EN", "ES"):
+            return code
+    except Exception:  # noqa: BLE001
+        pass
+    return "RU"
+
+
 def main() -> int:
     load_dotenv()
     logging.basicConfig(
@@ -72,20 +96,29 @@ def main() -> int:
     # Off unless asked for: it records every chat line in full.
     debug_log.configure(config.debug_capture_trace)
 
-    # The Qt entry point has always done this and the GTK one never did, so
-    # every Linux user got the default interface language regardless of what
-    # they picked in Settings — and the default is Russian.
-    tr.set_language(config.ui_language)
-
     # First run: no config file yet, or no translation API configured →
     # run the setup wizard (its own blocking GTK loop) before normal startup.
     if not os.path.exists(CONFIG_FILE) or not any_configured(config.providers):
+        # Give the wizard itself a reasonable display language BEFORE it opens.
+        # It has no config yet to base this on (config.ui_language is just the
+        # RU default, not a real signal), so guess from the OS locale instead —
+        # the wizard's own on-screen text otherwise defaults to Russian for
+        # every first-run user regardless of their system language.
+        tr.set_language(_guess_locale_lang())
+
         from app.setup_wizard_gtk import run_setup_wizard
 
         config = run_setup_wizard(config)
         if config is None:  # user closed the wizard without finishing
             return 0
 
+    # The Qt entry point has always done this and the GTK one never did, so
+    # every Linux user got the default interface language regardless of what
+    # they picked — and the default is Russian. Must run AFTER the wizard:
+    # applying it first used the pre-wizard config and ignored the language
+    # the user had just chosen on first run.
+    tr.set_language(config.ui_language)
+
     overlay = ChatOverlayGtk(config)
 
     # Reply translator (outgoing): default EN unless own language is EN.
@@ -124,6 +157,9 @@ def _open_settings() -> None:
         def _on_saved(updated: AppConfig) -> None:
             # Apply live: rebuild pipeline config (channels/langs).
             pipeline.update_config(_build_pipeline_config(updated))
+            # If this save is what FIRST configured a provider, this is the
+            # signal the startup failsafe was waiting on, start scanning now.
+            _start_pipeline_if_ready(updated)
             # Rebuild the reply translator so API key/priority changes take
             # effect without a restart.
             new_translator = TranslatorService.from_config(updated)
@@ -192,7 +228,7 @@ def _toggle_translation(enabled: bool) -> None:
     except Exception:  # noqa: BLE001
         logging.exception("history load failed (continuing without it)")
 
-    pipeline.start()
+    _start_pipeline_if_ready(config)
     try:
         return overlay.run()
     except KeyboardInterrupt:
diff --git a/app/setup_wizard_gtk.py b/app/setup_wizard_gtk.py
index 68f6dd3..2765c71 100644
--- a/app/setup_wizard_gtk.py
+++ b/app/setup_wizard_gtk.py
@@ -43,7 +43,7 @@
 
 class _WizardWindow(Gtk.ApplicationWindow):
     def __init__(self, app: Gtk.Application, config: AppConfig, result: dict) -> None:
-        super().__init__(application=app, title="BabelChat Setup")
+        super().__init__(application=app, title=tr("wizard.title"))
         self._config = config
         self._result = result  # {"config": AppConfig|None}
         self.set_default_size(520, 480)
@@ -51,10 +51,7 @@ def __init__(self, app: Gtk.Application, config: AppConfig, result: dict) -> Non
         self._stack = Gtk.Stack()
         self._stack.set_vexpand(True)
         self._pages: list[Gtk.Widget] = []
-        for builder in (self._page_welcome, self._page_api, self._page_wow, self._page_langs, self._page_ready):
-            page = builder()
-            self._pages.append(page)
-            self._stack.add_child(page)
+        self._build_pages()
         self._index = 0
 
         # Nav bar
@@ -79,6 +76,77 @@ def __init__(self, app: Gtk.Application, config: AppConfig, result: dict) -> Non
         self.set_child(root)
         self._sync_nav()
 
+    # ── page (re)building ────────────────────────────────────────────────
+    def _build_pages(self) -> None:
+        """(Re)build all pages from scratch so tr() text reflects the current
+        language. Called on init and again whenever the interface-language
+        dropdown changes, so the wizard updates live rather than only on the
+        NEXT run."""
+        snapshot = self._snapshot_fields() if self._pages else None
+
+        for page in self._pages:
+            self._stack.remove(page)
+        self._pages = []
+
+        for builder in (self._page_welcome, self._page_api, self._page_wow,
+                        self._page_langs, self._page_ready):
+            page = builder()
+            self._pages.append(page)
+            self._stack.add_child(page)
+
+        if snapshot is not None:
+            self._restore_fields(snapshot)
+            self._stack.set_visible_child(self._pages[self._index])
+
+    def _snapshot_fields(self) -> dict:
+        """Capture whatever the user has already entered, so switching the
+        interface language mid-wizard (a rebuild) doesn't lose it."""
+        snap: dict = {
+            "ui_lang": self._dd_code(self._ui_lang),
+            "priority": self._dd_code(self._priority),
+            "wow_path": self._wow_entry.get_text(),
+            "own_lang": self._dd_code(self._own_lang),
+            "target_lang": self._dd_code(self._target_lang),
+            "providers": {
+                pid: {key: entry.get_text() for key, entry in fields.items()}
+                for pid, fields in self._provider_entries.items()
+            },
+        }
+        return snap
+
+    def _restore_fields(self, snap: dict) -> None:
+        self._set_dd_code(self._ui_lang, snap["ui_lang"])
+        self._set_dd_code(self._priority, snap["priority"])
+        self._wow_entry.set_text(snap["wow_path"])
+        self._set_dd_code(self._own_lang, snap["own_lang"])
+        self._set_dd_code(self._target_lang, snap["target_lang"])
+        for pid, values in snap["providers"].items():
+            fields = self._provider_entries.get(pid, {})
+            for key, text in values.items():
+                entry = fields.get(key)
+                if entry is not None:
+                    entry.set_text(text)
+
+    @staticmethod
+    def _set_dd_code(dd: Gtk.DropDown, code: str) -> None:
+        codes = getattr(dd, "_codes", [])
+        try:
+            dd.set_selected(codes.index(code))
+        except ValueError:
+            pass
+
+    def _on_ui_lang_changed(self, dd: Gtk.DropDown, _param: object) -> None:
+        code = self._dd_code(dd)
+        if code == tr.get_language():
+            return
+        tr.set_language(code)
+        self._config.ui_language = code
+        # Rebuild so every page (including this one) re-renders in the new
+        # language immediately, instead of only taking effect next launch.
+        self._build_pages()
+        self._sync_nav()
+        self.set_title(tr("wizard.title"))
+
     # ── navigation ────────────────────────────────────────────────────────
     def _go(self, delta: int) -> None:
         self._index = max(0, min(len(self._pages) - 1, self._index + delta))
@@ -88,6 +156,7 @@ def _go(self, delta: int) -> None:
     def _sync_nav(self) -> None:
         last = self._index == len(self._pages) - 1
         self._back.set_sensitive(self._index > 0)
+        self._back.set_label(tr("wizard.back"))
         self._next.set_label(tr("wizard.start") if last else tr("wizard.next"))
         # Same step names the Qt wizard uses, from the one string that holds
         # them; the key wants a name as well as the numbers.
@@ -146,7 +215,14 @@ def _page_welcome(self) -> Gtk.Widget:
         )
         row = Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL, spacing=8)
         row.append(self._body(tr("wizard.welcome.ui_lang")))
-        self._ui_lang = self._dropdown(_UI_LANGS, self._config.ui_language or "EN")
+        # Source the selection from tr (what's actually on screen right now),
+        # not self._config.ui_language directly — before anything is saved,
+        # config.ui_language is just its raw default and can disagree with
+        # the language the page text is actually rendered in (e.g. the
+        # locale-guessed language on first open), showing a dropdown value
+        # that doesn't match what the user is looking at.
+        self._ui_lang = self._dropdown(_UI_LANGS, tr.get_language())
+        self._ui_lang.connect("notify::selected", self._on_ui_lang_changed)
         row.append(self._ui_lang)
         box.append(row)
         return box