Offer to apply archinstall language to target system locale and timezone

After picking an installer language with a known locale mapping, prompt
the user to apply sys_lang, sys_enc, console_font, and (where the country
maps to a single IANA zone) timezone to the target system. Each row is
shown only when its target value differs from the current setting, so
re-picking a language with fewer mappings resets stale fields too.

default_timezone is set in languages.json only for unambiguous single
mainland zones; multi-zone countries (en_US, ru_RU, es_ES, pt_BR, ...)
and codes that span countries are left without a default. Timezone
candidates are validated against list_timezones().

Author: Softer

archinstall/lib/global_menu.py

@@ -8,11 +8,14 @@
 from archinstall.lib.bootloader.utils import validate_bootloader_layout
 from archinstall.lib.configuration import ConfigurationOutput, save_config
 from archinstall.lib.disk.disk_menu import DiskLayoutConfigurationMenu
+from archinstall.lib.exceptions import SysCallError
 from archinstall.lib.general.general_menu import select_hostname, select_ntp, select_timezone
 from archinstall.lib.general.system_menu import select_kernel, select_swap
 from archinstall.lib.hardware import SysInfo
+from archinstall.lib.locale import list_timezones
 from archinstall.lib.locale.locale_menu import LocaleMenu
 from archinstall.lib.menu.abstract_menu import AbstractMenu, SpecialMenuKey
+from archinstall.lib.menu.helpers import Confirmation
 from archinstall.lib.mirror.mirror_handler import MirrorListHandler
 from archinstall.lib.mirror.mirror_menu import MirrorMenu
 from archinstall.lib.models.application import ApplicationConfiguration, ZramConfiguration
@@ -27,13 +30,14 @@
 from archinstall.lib.models.pacman import PacmanConfiguration
 from archinstall.lib.models.profile import ProfileConfiguration
 from archinstall.lib.network.network_menu import select_network
-from archinstall.lib.output import FormattedOutput
+from archinstall.lib.output import FormattedOutput, debug
 from archinstall.lib.packages.packages import list_available_packages, select_additional_packages
 from archinstall.lib.pacman.config import PacmanConfig
 from archinstall.lib.pacman.pacman_menu import PacmanMenu
-from archinstall.lib.translationhandler import Language, tr, translation_handler
+from archinstall.lib.translationhandler import DEFAULT_TIMEZONE, Language, tr, translation_handler
 from archinstall.tui.ui.components import tui
 from archinstall.tui.ui.menu_item import MenuItem, MenuItemGroup
+from archinstall.tui.ui.result import ResultType
 
 
 class GlobalMenu(AbstractMenu[None]):
@@ -160,7 +164,7 @@ def _get_menu_options(self) -> list[MenuItem]:
 			MenuItem(
 				text=tr('Timezone'),
 				action=select_timezone,
-				value='UTC',
+				value=DEFAULT_TIMEZONE,
 				preview_action=self._prev_tz,
 				key='timezone',
 			),
@@ -254,8 +258,80 @@ async def _select_archinstall_language(self, preset: Language) -> Language:
 
 		self._update_lang_text()
 
+		await self._maybe_apply_language_to_locale(language)
+
 		return language
 
+	async def _maybe_apply_language_to_locale(self, language: Language) -> None:
+		"""Offer to mirror the selected archinstall language into the target system locale.
+
+		Triggered only when the language has a sys_lang mapping, since otherwise
+		there is no target locale to offer. Console font and timezone rows are
+		added to the prompt only when their language-derived target value differs
+		from the current setting, so re-picking a language with fewer mappings
+		(for example switching from Ukrainian to German, which has no console_font
+		of its own) resets the stale Ukrainian font alongside the new locale.
+		"""
+		if not language.sys_lang:
+			return
+
+		locale_item = self._item_group.find_by_key('locale_config')
+		locale_config: LocaleConfiguration | None = locale_item.value
+		if not locale_config:
+			return
+
+		tz_item = self._item_group.find_by_key('timezone')
+		current_tz: str = tz_item.value or DEFAULT_TIMEZONE
+		target_tz = language.target_timezone
+		offer_tz = self._is_timezone_offerable(target_tz, current_tz)
+
+		diff = locale_config.language_diff(language)
+		if diff.is_empty() and not offer_tz:
+			return
+
+		rows = diff.labeled_rows()
+		if offer_tz:
+			rows.append((tr('Timezone'), target_tz))
+
+		if not await self._confirm_locale_apply(rows):
+			return
+
+		locale_config.apply_language_diff(diff)
+		if offer_tz:
+			tz_item.value = target_tz
+
+	def _is_timezone_offerable(self, target_tz: str, current_tz: str) -> bool:
+		"""Return True when the candidate differs from the current and exists in tzdata.
+
+		The same source the timezone menu reads from, so we never offer a value
+		the user could not have selected manually. UTC is always present, so this
+		is effectively a no-op for the reset-to-default case.
+		"""
+		if target_tz == current_tz:
+			return False
+		try:
+			return target_tz in list_timezones()
+		except SysCallError as err:
+			debug(f'Failed to validate target timezone {target_tz}: {err}')
+			return False
+
+	async def _confirm_locale_apply(self, rows: list[tuple[str, str]]) -> bool:
+		"""Render and show the confirmation dialog for the locale changes."""
+		label_w = max(len(label) for label, _ in rows)
+		data_lines = [f'  {label.ljust(label_w)}  : {value}' for label, value in rows]
+
+		question = tr('Use this language as the target system language as well?')
+		header = tr('The following settings will be applied:')
+
+		# The TUI centers every line of the prompt independently, so pad all
+		# lines to a common width; otherwise the colon column drifts.
+		width = max(len(question), len(header), *(len(line) for line in data_lines))
+		separator = '=' * width
+		prompt = question.ljust(width) + '\n\n' + header.ljust(width) + '\n' + separator + '\n' + '\n'.join(line.ljust(width) for line in data_lines) + '\n'
+
+		result = await Confirmation(header=prompt, preset=True).show()
+		return result.type_ == ResultType.Selection and result.item() == MenuItem.yes()
+
 	def _prev_archinstall_language(self, item: MenuItem) -> str | None:
 		if not item.value:
 			return None

archinstall/lib/models/locale.py

@@ -2,7 +2,36 @@
 from typing import Any, Self
 
 from archinstall.lib.locale.utils import get_kb_layout
-from archinstall.lib.translationhandler import tr
+from archinstall.lib.translationhandler import DEFAULT_CONSOLE_FONT, Language, tr
+
+
+@dataclass
+class LocaleLanguageDiff:
+	"""Locale fields to write when applying a Language to a LocaleConfiguration.
+
+	Each field carries the new value, or None when no change is needed. sys_enc
+	is paired with sys_lang so the encoding row is shown alongside the locale
+	row in the confirmation dialog, even when the encoding portion itself does
+	not change.
+	"""
+
+	sys_lang: str | None = None
+	sys_enc: str | None = None
+	console_font: str | None = None
+
+	def is_empty(self) -> bool:
+		return self.sys_lang is None and self.sys_enc is None and self.console_font is None
+
+	def labeled_rows(self) -> list[tuple[str, str]]:
+		"""Return [(label, value)] for fields that would change."""
+		rows: list[tuple[str, str]] = []
+		if self.sys_lang is not None:
+			rows.append((tr('Locale language'), self.sys_lang))
+		if self.sys_enc is not None:
+			rows.append((tr('Locale encoding'), self.sys_enc))
+		if self.console_font is not None:
+			rows.append((tr('Console font'), self.console_font))
+		return rows
 
 
 @dataclass
@@ -14,7 +43,7 @@ class LocaleConfiguration:
 	# can be checked using
 	# zgrep "CONFIG_FONT" /proc/config.gz
 	# https://wiki.archlinux.org/title/Linux_console#Font
-	console_font: str = 'default8x16'
+	console_font: str = DEFAULT_CONSOLE_FONT
 
 	@classmethod
 	def default(cls) -> Self:
@@ -38,6 +67,36 @@ def preview(self) -> str:
 		output += '{}: {}'.format(tr('Console font'), self.console_font)
 		return output
 
+	def language_diff(self, language: Language) -> LocaleLanguageDiff:
+		"""Compute the locale fields that would change if applying this language.
+
+		Returns an empty diff for languages without a sys_lang mapping. console_font
+		is offered when the language-derived target value differs - so re-picking
+		a language with fewer mappings still resets stale fonts left over from a
+		previous pick.
+		"""
+		diff = LocaleLanguageDiff()
+		if not language.sys_lang:
+			return diff
+
+		if self.sys_lang != language.sys_lang:
+			diff.sys_lang = language.sys_lang
+			diff.sys_enc = language.target_sys_enc or self.sys_enc
+
+		target_font = language.target_console_font
+		if self.console_font != target_font:
+			diff.console_font = target_font
+
+		return diff
+
+	def apply_language_diff(self, diff: LocaleLanguageDiff) -> None:
+		if diff.sys_lang is not None:
+			self.sys_lang = diff.sys_lang
+		if diff.sys_enc is not None:
+			self.sys_enc = diff.sys_enc
+		if diff.console_font is not None:
+			self.console_font = diff.console_font
+
 	def _load_config(self, args: dict[str, str]) -> None:
 		if 'sys_lang' in args:
 			self.sys_lang = args['sys_lang']

archinstall/lib/translationhandler.py

@@ -21,12 +21,31 @@ class Language:
 	translation_percent: int
 	translated_lang: str | None
 	console_font: str | None = None
+	sys_lang: str | None = None
+	default_timezone: str | None = None
 
 	@property
 	def display_name(self) -> str:
 		name = self.name_en
 		return f'{name} ({self.translation_percent}%)'
 
+	@property
+	def target_sys_enc(self) -> str | None:
+		"""Encoding portion of sys_lang (e.g. 'UTF-8' from 'uk_UA.UTF-8'). None when sys_lang has no '.'."""
+		if self.sys_lang and '.' in self.sys_lang:
+			return self.sys_lang.split('.', 1)[1]
+		return None
+
+	@property
+	def target_console_font(self) -> str:
+		"""Console font implied by this language; falls back to the system default."""
+		return self.console_font or DEFAULT_CONSOLE_FONT
+
+	@property
+	def target_timezone(self) -> str:
+		"""Timezone implied by this language; falls back to UTC."""
+		return self.default_timezone or DEFAULT_TIMEZONE
+
 	def is_match(self, lang_or_translated_lang: str) -> bool:
 		if self.name_en == lang_or_translated_lang:
 			return True
@@ -38,7 +57,8 @@ def json(self) -> str:
 		return self.name_en
 
 
-_DEFAULT_FONT = 'default8x16'
+DEFAULT_CONSOLE_FONT = 'default8x16'
+DEFAULT_TIMEZONE = 'UTC'
 _ENV_FONT = os.environ.get('FONT')
 
 
@@ -69,7 +89,7 @@ def _set_font(self, font_name: str | None) -> bool:
 		if not running_from_iso():
 			return False
 
-		target = font_name or _DEFAULT_FONT
+		target = font_name or DEFAULT_CONSOLE_FONT
 		try:
 			SysCommand(['setfont', target])
 			return True
@@ -132,6 +152,8 @@ def _get_translations(self) -> list[Language]:
 			lang = mapping_entry['lang']
 			translated_lang = mapping_entry.get('translated_lang', None)
 			console_font = mapping_entry.get('console_font', None)
+			sys_lang = mapping_entry.get('sys_lang', None)
+			default_timezone = mapping_entry.get('default_timezone', None)
 
 			try:
 				# get a translation for a specific language
@@ -146,7 +168,7 @@ def _get_translations(self) -> list[Language]:
 					# prevent cases where the .pot file is out of date and the percentage is above 100
 					percent = min(100, percent)
 
-				language = Language(abbr, lang, translation, percent, translated_lang, console_font)
+				language = Language(abbr, lang, translation, percent, translated_lang, console_font, sys_lang, default_timezone)
 				languages.append(language)
 			except FileNotFoundError as err:
 				raise FileNotFoundError(f"Could not locate language file for '{lang}': {err}")

archinstall/locales/base.pot

@@ -163,6 +163,12 @@ msgstr ""
 msgid "Archinstall language"
 msgstr ""
 
+msgid "Use this language as the target system language as well?"
+msgstr ""
+
+msgid "The following settings will be applied:"
+msgstr ""
+
 msgid "Wipe all selected drives and use a best-effort default partition layout"
 msgstr ""