fix(voices): prevent mixed-language Kokoro selections

src/components/player/VoicesControlBase.tsx

@@ -6,6 +6,7 @@ import {
 import { ChevronUpDownIcon, AudioWaveIcon, CheckIcon } from '@/components/icons/Icons';
 import { useEffect, useMemo, useState } from 'react';
 import { buildKokoroVoiceString, parseKokoroVoiceNames } from '@/lib/shared/kokoro';
+import { keepKokoroVoicesInOneLanguage } from '@/lib/shared/language';
 import { type TtsProviderType } from '@/lib/shared/tts-provider-catalog';
 import { resolveTtsProviderModelPolicy } from '@/lib/shared/tts-provider-policy';
 import { SharedListboxButton, SharedListboxOption, SharedListboxOptions, cn } from '@/components/ui';
@@ -70,8 +71,13 @@ export function VoicesControlBase({
     if (initial.length > maxVoices) {
       initial = initial.slice(0, maxVoices);
     }
+    initial = keepKokoroVoicesInOneLanguage(initial);
     setSelectedVoices(initial);
-  }, [isKokoro, maxVoices, voice, availableVoices]);
+    const combined = buildKokoroVoiceString(initial);
+    if (combined && combined !== voice) {
+      onChangeVoice(combined);
+    }
+  }, [isKokoro, maxVoices, voice, availableVoices, onChangeVoice]);
 
   const currentVoice = useMemo(() => {
     if (isKokoro && maxVoices > 1) {
@@ -101,15 +107,19 @@ export function VoicesControlBase({
           onChange={(vals: string[]) => {
             if (!vals || vals.length === 0) return;
 
-            let next = vals;
-            if (vals.length > maxVoices) {
-              const newlyAdded = vals.find((v) => !selectedVoices.includes(v));
+            const newlyAdded = vals.find((v) => !selectedVoices.includes(v));
+            let next = keepKokoroVoicesInOneLanguage(vals, newlyAdded);
+            if (next.length > maxVoices) {
               if (newlyAdded) {
-                const lastPrev = selectedVoices[selectedVoices.length - 1] ?? selectedVoices[0] ?? '';
-                const pair = Array.from(new Set([lastPrev, newlyAdded])).filter(Boolean);
-                next = pair.slice(0, maxVoices);
+                const compatiblePrevious = selectedVoices.filter(
+                  (voiceId) => voiceId !== newlyAdded && next.includes(voiceId),
+                );
+                next = [
+                  ...compatiblePrevious.slice(-(maxVoices - 1)),
+                  newlyAdded,
+                ];
               } else {
-                next = vals.slice(-maxVoices);
+                next = next.slice(-maxVoices);
               }
             }
 

src/lib/shared/language.ts

@@ -90,6 +90,21 @@ export function getKokoroVoiceLanguages(voice: string | null | undefined): strin
   ));
 }
 
+export function keepKokoroVoicesInOneLanguage(
+  voices: string[],
+  preferredVoice?: string | null,
+): string[] {
+  const preferredLanguage = getKokoroVoiceLanguages(preferredVoice)[0]
+    ?? voices.flatMap((voice) => getKokoroVoiceLanguages(voice))[0];
+  if (!preferredLanguage) return voices;
+
+  const preferredBaseLanguage = toBaseLanguageCode(preferredLanguage);
+  return voices.filter((voice) => {
+    const voiceLanguage = getKokoroVoiceLanguages(voice)[0];
+    return !voiceLanguage || toBaseLanguageCode(voiceLanguage) === preferredBaseLanguage;
+  });
+}
+
 export function resolveTtsLanguage(input: {
   configuredLanguage?: string | null;
   voice?: string | null;
@@ -130,14 +145,7 @@ export function getTtsLanguageCompatibilityWarnings(input: {
     );
   }
 
-  if (voiceBaseLanguages.size > 1) {
-    warnings.push(
-      `Selected Kokoro voices use multiple languages (${voiceLanguages.map(getLanguageDisplayName).join(', ')}).`,
-    );
-    return warnings;
-  }
-
-  const voiceLanguage = voiceLanguages[0];
+  const voiceLanguage = voiceBaseLanguages.size === 1 ? voiceLanguages[0] : undefined;
   if (voiceLanguage && toBaseLanguageCode(voiceLanguage) !== documentBaseLanguage) {
     warnings.push(
       `Selected Kokoro voice is ${getLanguageDisplayName(voiceLanguage)}, but the document is ${getLanguageDisplayName(documentLanguage)}.`,

tests/unit/language.vitest.spec.ts

@@ -5,6 +5,7 @@ import { resolve } from 'path';
 import {
   getTtsLanguageCompatibilityWarnings,
   inferKokoroLanguageFromVoice,
+  keepKokoroVoicesInOneLanguage,
   normalizeOptionalLanguageTag,
   normalizeUnicodeToken,
   resolveTtsLanguage,
@@ -27,6 +28,23 @@ describe('multilingual language utilities', () => {
     expect(inferKokoroLanguageFromVoice('ff_siwis+jf_alpha')).toBeNull();
   });
 
+  test('keeps Kokoro multi-voice selections within the newly selected language', () => {
+    expect(keepKokoroVoicesInOneLanguage(
+      ['af_sarah', 'bf_emma', 'jf_alpha'],
+      'jf_alpha',
+    )).toEqual(['jf_alpha']);
+
+    expect(keepKokoroVoicesInOneLanguage(
+      ['zf_xiaobei', 'zm_yunxi', 'af_sarah'],
+      'zm_yunxi',
+    )).toEqual(['zf_xiaobei', 'zm_yunxi']);
+
+    expect(keepKokoroVoicesInOneLanguage(
+      ['af_sarah', 'bf_emma'],
+      'bf_emma',
+    )).toEqual(['af_sarah', 'bf_emma']);
+  });
+
   test('normalizes valid EPUB metadata language tags and rejects invalid metadata', () => {
     expect(normalizeOptionalLanguageTag(' ja-jp ')).toBe('ja-JP');
     expect(normalizeOptionalLanguageTag('fr, en')).toBe('fr');
@@ -53,9 +71,7 @@ describe('multilingual language utilities', () => {
       model: 'kokoro',
       voice: 'ff_siwis+jf_alpha',
       documentLanguage: 'fr',
-    })).toEqual([
-      'Selected Kokoro voices use multiple languages (French, Japanese).',
-    ]);
+    })).toEqual([]);
 
     expect(getTtsLanguageCompatibilityWarnings({
       model: 'kokoro',