Contain JNI logging failures and preserve UTF-8 payloads

tools/chatgui-android/app/src/test/java/com/utun/chat/data/NativeLogContractTest.kt

@@ -0,0 +1,20 @@
+package com.utun.chat.data
+
+import java.io.File
+import org.junit.Assert.*
+import org.junit.Test
+
+/** Сопоставляет настоящий JNI lookup с JVM-дескриптором скомпилированного Kotlin callback. */
+class NativeLogContractTest {
+    @Test fun nativeLookupMatchesTheCompiledKotlinByteArrayCallback() {
+        val method = LogManager::class.java.declaredMethods.single { it.name == "onNativeLog" }
+        val descriptor = "(" + method.parameterTypes.joinToString("") {
+            if (it == Int::class.javaPrimitiveType) "I" else it.name.replace('.', '/')
+        } + ")" + if (method.returnType == Void.TYPE) "V" else method.returnType.name
+        val source = File(requireNotNull(System.getProperty("utun.androidBridgeSource"))).readText()
+        val native = Regex("GetMethodID\\(env, cls, \\\"onNativeLog\\\", \\\"([^\\\"]+)\\\"\\)").find(source)
+        assertNotNull("JNI onNativeLog lookup missing", native)
+        assertEquals("(I[B[B)V", descriptor)
+        assertEquals(descriptor, native!!.groupValues[1])
+    }
+}