Preserve Android feedback state and supplementary Unicode characters

tools/chatgui-android/app/src/main/java/com/utun/chat/viewmodel/ChatViewModel.kt

@@ -1249,6 +1249,7 @@ class ChatViewModel : ViewModel() {
         r.sendMessage(ch.id, text)
         viewModelScope.launch {
             _messages.value = withContext(Dispatchers.IO) { r.getMessages(ch.id) }
+                .map { it.copy(feedback = feedbackCache[it.messageId]) }
             refreshChannels()
         }
     }

tools/chatgui-android/jni_bridge/android_jni_bridge.c

@@ -1923,7 +1923,21 @@ JNIEXPORT jstring JNICALL Java_com_utun_chat_data_NativeLib_nativeGetMessages(
     (void)thiz;
     const char* ch = (*env)->GetStringUTFChars(env, channelId, NULL);
     char* json = utun_bridge_get_messages_json(ch, (int)limit);
-    jstring result = (*env)->NewStringUTF(env, json);
+    /* String(byte[], UTF-8) корректно восстанавливает четырёхбайтовые emoji. */
+    jclass strings = (*env)->FindClass(env, "java/lang/String");
+    jmethodID constructor = strings ? (*env)->GetMethodID(env, strings, "<init>", "([BLjava/lang/String;)V") : NULL;
+    size_t bytes = json ? strlen(json) : 0;
+    jbyteArray data = (*env)->NewByteArray(env, (jsize)bytes);
+    jstring charset = (*env)->NewStringUTF(env, "UTF-8");
+    jstring result = NULL;
+    if (constructor && data && charset) {
+        (*env)->SetByteArrayRegion(env, data, 0, (jsize)bytes, (const jbyte*)json);
+        if (!(*env)->ExceptionCheck(env)) result = (jstring)(*env)->NewObject(env, strings, constructor, data, charset);
+    }
+    if (!result) DEBUG_ERROR(DEBUG_CATEGORY_CHAT, "bridge: UTF-8 message result allocation failed");
+    if (data) (*env)->DeleteLocalRef(env, data);
+    if (charset) (*env)->DeleteLocalRef(env, charset);
+    if (strings) (*env)->DeleteLocalRef(env, strings);
     u_free(json);
     (*env)->ReleaseStringUTFChars(env, channelId, ch);
     return result;