diff --git a/src/backend/wayland/wl_backend.c b/src/backend/wayland/wl_backend.c
index a99f638..81bfce7 100644
--- a/src/backend/wayland/wl_backend.c
+++ b/src/backend/wayland/wl_backend.c
@@ -959,9 +959,20 @@ wl_display_open(const char *name)
      * is set (run inside an existing Wayland compositor), otherwise headless.
      * Both modes always include a headless backend (headless_inner) so that
      * wlr_headless_add_input_device works regardless of nesting. */
+    /* Auto-detect nested mode: if WAYLAND_DISPLAY is set we are running inside
+     * an existing Wayland session and should use wlr_wl_backend so the
+     * compositor appears as a window on the host desktop.
+     * WMAKER_WAYLAND_NESTED=0 can be used to force headless even when
+     * WAYLAND_DISPLAY is present (e.g. for automated testing). */
     {
         const char *nested_env = getenv("WMAKER_WAYLAND_NESTED");
-        wl_state.is_nested = (nested_env && nested_env[0]) ? 1 : 0;
+        const char *wayland_display = getenv("WAYLAND_DISPLAY");
+        if (nested_env && nested_env[0] == '0')
+            wl_state.is_nested = 0;   /* explicit override: force headless */
+        else if (nested_env && nested_env[0])
+            wl_state.is_nested = 1;   /* explicit override: force nested */
+        else
+            wl_state.is_nested = (wayland_display && wayland_display[0]) ? 1 : 0;
     }
 
     /* Always create a headless backend for input devices. */
diff --git a/tests/wl-smoke-test.sh b/tests/wl-smoke-test.sh
index 5f5aa87..1d05c71 100755
--- a/tests/wl-smoke-test.sh
+++ b/tests/wl-smoke-test.sh
@@ -179,7 +179,7 @@ if [ -z "$XDG_RUNTIME_DIR" ]; then
     export XDG_RUNTIME_DIR
 fi
 
-WMAKER_USE_WAYLAND=1 src/wmaker \
+WMAKER_USE_WAYLAND=1 WMAKER_WAYLAND_NESTED=0 src/wmaker \
     --no-dock --no-clip --no-autolaunch \
     --dont-restore --static \
     --for-real 2>/tmp/wl-smoke-stderr &