1 files changed, 43 insertions, 9 deletions
diff --git a/src/state/persisted/schema.ts b/src/state/persisted/schema.ts
index 331a111a2..804017949 100644
--- a/src/state/persisted/schema.ts
+++ b/src/state/persisted/schema.ts
@@ -1,7 +1,8 @@
 import {z} from 'zod'
 
+import {deviceLanguageCodes, deviceLocales} from '#/locale/deviceLocales'
+import {findSupportedAppLanguage} from '#/locale/helpers'
 import {logger} from '#/logger'
-import {deviceLocales} from '#/platform/detection'
 import {PlatformInfo} from '../../../modules/expo-bluesky-swiss-army'
 
 const externalEmbedOptions = ['show', 'hide'] as const
@@ -55,10 +56,39 @@ const schema = z.object({
     lastEmailConfirm: z.string().optional(),
   }),
   languagePrefs: z.object({
-    primaryLanguage: z.string(), // should move to server
-    contentLanguages: z.array(z.string()), // should move to server
-    postLanguage: z.string(), // should move to server
+    /**
+     * The target language for translating posts.
+     *
+     * BCP-47 2-letter language code without region.
+     */
+    primaryLanguage: z.string(),
+    /**
+     * The languages the user can read, passed to feeds.
+     *
+     * BCP-47 2-letter language codes without region.
+     */
+    contentLanguages: z.array(z.string()),
+    /**
+     * The language(s) the user is currently posting in, configured within the
+     * composer. Multiple languages are psearate by commas.
+     *
+     * BCP-47 2-letter language code without region.
+     */
+    postLanguage: z.string(),
+    /**
+     * The user's post language history, used to pre-populate the post language
+     * selector in the composer. Within each value, multiple languages are
+     * separated by values.
+     *
+     * BCP-47 2-letter language codes without region.
+     */
     postLanguageHistory: z.array(z.string()),
+    /**
+     * The language for UI translations in the app.
+     *
+     * BCP-47 2-letter language code with or without region,
+     * to match with {@link AppLanguage}.
+     */
     appLanguage: z.string(),
   }),
   requireAltTextEnabled: z.boolean(), // should move to server
@@ -108,13 +138,17 @@ export const defaults: Schema = {
     lastEmailConfirm: undefined,
   },
   languagePrefs: {
-    primaryLanguage: deviceLocales[0] || 'en',
-    contentLanguages: deviceLocales || [],
-    postLanguage: deviceLocales[0] || 'en',
-    postLanguageHistory: (deviceLocales || [])
+    primaryLanguage: deviceLanguageCodes[0] || 'en',
+    contentLanguages: deviceLanguageCodes || [],
+    postLanguage: deviceLanguageCodes[0] || 'en',
+    postLanguageHistory: (deviceLanguageCodes || [])
       .concat(['en', 'ja', 'pt', 'de'])
       .slice(0, 6),
-    appLanguage: deviceLocales[0] || 'en',
+    // try full language tag first, then fallback to language code
+    appLanguage: findSupportedAppLanguage([
+      deviceLocales.at(0)?.languageTag,
+      deviceLanguageCodes[0],
+    ]),
   },
   requireAltTextEnabled: false,
   largeAltBadgeEnabled: false,