From 3112f7c47e41611b719914c7cca39647ae8181db Mon Sep 17 00:00:00 2001
From: schroda <50052685+schroda@users.noreply.github.com>
Date: Mon, 6 Jul 2026 23:57:04 +0200
Subject: [PATCH] Fix native language codes usage in "browse languages"

The native language code returned by the browser could be a code that is not included in the defined ISOLanguages object. E.g. "en-GB" while the object only has "en".

This caused the "English" browse language to not be able to get selected as an allowed language.
---
 CHANGELOG.md                                |  1 +
 src/features/metadata/Metadata.constants.ts | 17 +++++++++++++++++
 src/lib/ISOLanguageUtil.ts                  |  4 +++-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f0712607..aa07bc7b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -72,6 +72,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 - (**Reader**) Fix preserving scroll position
 - (**Reader**) Fix missing gap between chapters in continuous vertical and horizontal reading modes with disabled transition page
 - (**Browse**) Fix showing only nsfw sources in the browse source page when the "show nsfw" setting is disabled
+- (**Browse**) Fix not being able to select some languages as an "allowed language" in some situations (e.g., browser native language "en-GB" prevented "English" from getting visually shown as enabled)
 - (**Manga/Library**) Fix mark as read/unread option not being disabled for manga without any chapters
 - (**Manga/Library**) Fix delete/download option not being disabled for manga without any chapters
 - (**Source**) Fix changing configuration settings with multi option selection where a selected option does not exist anymore. (E.g. Komgas "Default libraries" setting, still having a library selected that has been deleted)
diff --git a/src/features/metadata/Metadata.constants.ts b/src/features/metadata/Metadata.constants.ts
index da4dbc47..a00098ff 100644
--- a/src/features/metadata/Metadata.constants.ts
+++ b/src/features/metadata/Metadata.constants.ts
@@ -726,6 +726,23 @@ export const METADATA_MIGRATIONS: IMetadataMigration[] = [
                 })) satisfies IMetadataMigration['values'])(),
         ],
     },
+    {
+        values: [
+            {
+                key: 'browseLanguages',
+                oldValue: /^\[.*]$/g,
+                newValue: (browseLanguagesValue) => {
+                    const convertedBrowseLanguages = convertToObject<string[]>(browseLanguagesValue, []);
+
+                    const convertedToValidIsoCodes = convertedBrowseLanguages.map(
+                        (language) => getISOLanguage(language)?.isoCode ?? language,
+                    );
+
+                    return JSON.stringify(convertedToValidIsoCodes);
+                },
+            },
+        ],
+    },
 ];
 
 export const ALL_APP_METADATA_KEY_PREFIXES: string[] = [
diff --git a/src/lib/ISOLanguageUtil.ts b/src/lib/ISOLanguageUtil.ts
index 11224bcc..872ffbbb 100644
--- a/src/lib/ISOLanguageUtil.ts
+++ b/src/lib/ISOLanguageUtil.ts
@@ -116,7 +116,9 @@ const toUniqueISOLanguageCodes = (codes: string[]): string[] => {
 };
 
 export function getPreferredISOLanguageCodes(): readonly string[] {
-    const preferredLanguages = toUniqueISOLanguageCodes([...navigator.languages]);
+    const preferredLanguages = toUniqueISOLanguageCodes([...navigator.languages]).map(
+        (language) => getISOLanguage(language)?.isoCode ?? language,
+    );
 
     if (!preferredLanguages.length) {
         return [DEFAULT_LANGUAGE];