Honor the system default speech voice

tests/voice.test.cjs

@@ -117,17 +117,19 @@ test('recognition watchdog closes a session that never ends and permits retry',
   assert.equal(h.recognitions.length, 2);
 });
 
-test('TTS selects Swedish fallback, applies rate, and cancellation invalidates callbacks', () => {
+test('TTS uses the system default voice unless a named Swedish voice is selected', () => {
   const h = makeHarness();
   h.controller.update({mode: 'game-voice', rate: 1.4});
   assert.equal(h.controller.speak('Hej.'), true);
   const first = h.utterances[0];
   assert.equal(first.lang, 'sv-SE');
   assert.equal(first.rate, 1.4);
-  assert.equal(first.voice.name, 'Svensk');
+  assert.equal(first.voice, null);
   h.controller.cancelSpeech();
   first.onend();
   assert.equal(h.controller.getState(), 'IDLE');
+  assert.equal(h.controller.speak('Namngiven röst.', {voiceName: 'Svensk'}), true);
+  assert.equal(h.utterances.at(-1).voice.name, 'Svensk');
 });
 
 test('a player gesture restores the iOS speech primer after cancelling a queued reply', () => {

voice.js

@@ -233,9 +233,14 @@
       utterance.pitch = isNarrator ? 1 : Math.min(2, Math.max(0, Number(voiceOptions.pitch ?? profile.pitch ?? identityProfile.pitch) || 1));
       const requestedName = voiceOptions.voiceName || profile.voiceName || settings.voiceName;
       const voices = availableVoices();
-      utterance.voice = voices.find(voice => voice.name === requestedName)
+      // An empty selection means the operating system should choose its
+      // default voice for the requested language. Forcing the first voice
+      // returned by WebKit can select a voice that is listed but cannot speak.
+      utterance.voice = requestedName
+        ? voices.find(voice => voice.name === requestedName)
           || voices.find(voice => /^sv(-|$)/i.test(voice.lang))
-        || null;
+          || null
+        : null;
       utterance.onstart = () => {
         if (token !== generation) return;
         if (speechStartTimer !== null) win.clearTimeout(speechStartTimer);