diff --git a/native_bridge/src/main.cpp b/native_bridge/src/main.cpp
index baf43d4..27fc909 100644
--- a/native_bridge/src/main.cpp
+++ b/native_bridge/src/main.cpp
@@ -721,7 +721,9 @@ int main(int argc, char* argv[]) {
     // fx-gui port reader) survives FreeConsole.
     if (!std::getenv("SF_KEEP_CONSOLE")) FreeConsole();
 #endif
-    std::cout << "[NativeBridge] Starting DAW Host Bridge Engine..." << std::endl;
+    // stderr, not stdout: stdout is reserved for machine-readable output in
+    // one-shot modes (--scan JSON, --fx-gui "SF_FXGUI_PORT=...").
+    std::cerr << "[NativeBridge] Starting DAW Host Bridge Engine..." << std::endl;
 #ifdef _WIN32
     // Disable Power Throttling (Efficiency Mode) for this background process
 #ifndef PROCESS_POWER_THROTTLING_IGNORE_TIMER_RESOLUTION