diff --git a/src/main.cpp b/src/main.cpp
index 45a5eaf..eb723a8 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -49,6 +49,7 @@
 #ifdef _WIN32
 #include "platform/windows_backdrop.h"
 #include <windows.h>
+#include <io.h>
 #include <dwmapi.h>
 #include <shlobj.h>
 #include <propkey.h>
@@ -553,7 +554,7 @@ static void drawWindowBackdrop(dragonx::App& app, ImDrawList* bgDL, ImVec2 p0, I
 }
 
 // ── Window-dimension diagnostic tracer ──────────────────────────────────────────────────────
-// Always-on (writes to stderr → dragonx-debug.log on Windows) so it's visible in release builds,
+// Always-on (writes to stderr → dragonx-stdout.log on Windows) so it's visible in release builds,
 // unlike DRAGONX_DEBUG-gated DEBUG_LOGF. Grep the log for "[WINLOG]" to trace how the window size
 // changes when dragging between monitors of different DPI. Low volume — only fires on window
 // resize / move / DPI-scale events. TODO: remove once the multi-monitor sizing bug is resolved.
@@ -919,8 +920,10 @@ int main(int argc, char* argv[])
     // above so the two writers don't interleave/contend on one file.
     {
         std::string logPath = (std::filesystem::path(dragonx::util::Platform::getObsidianDragonDir()) / "dragonx-stdout.log").string();
-        freopen(logPath.c_str(), "w", stdout);
-        freopen(logPath.c_str(), "a", stderr);
+        freopen(logPath.c_str(), "w", stdout);    // per-run truncation
+        freopen("NUL", "w", stderr);              // GUI subsystem may have no valid fd 2 — give it one first
+        _dup2(_fileno(stdout), _fileno(stderr));  // stderr now shares stdout's handle + file offset
+        setvbuf(stderr, nullptr, _IONBF, 0);      // keep stderr unbuffered (crash diagnostics)
     }
     // Install crash handler for diagnostics
     SetUnhandledExceptionFilter(CrashHandler);