diff --git a/src/backend/wayland/wl_backend.c b/src/backend/wayland/wl_backend.c
index 3745ef9..15e03ef 100644
--- a/src/backend/wayland/wl_backend.c
+++ b/src/backend/wayland/wl_backend.c
@@ -51,6 +51,9 @@
  * (all XDG toplevels support close); wClientSendProtocol dispatches
  * client_close in the Wayland path so MC_CLOSE is enabled and kill_close=0.
  * wManageWindow succeeded log now includes kill_close= field.
+ * Phase 64: zxdg_decoration_manager_v1 advertised; new_toplevel_decoration
+ * listener responds immediately with CLIENT_SIDE mode so clients draw their
+ * own title bars (no X11 frame rendering in the Wayland path).
  */
 
 #ifdef HAVE_CONFIG_H
@@ -74,6 +77,7 @@
 #include <wlr/types/wlr_seat.h>
 #include <wlr/types/wlr_keyboard.h>
 #include <wlr/types/wlr_xdg_shell.h>
+#include <wlr/types/wlr_xdg_decoration_v1.h>
 #include <wlr/util/box.h>
 /* Generated xdg-shell protocol implementation (Wayland glue code) */
 #include "protocols/xdg-shell-protocol.c"
@@ -135,6 +139,9 @@ struct wl_compositor_state {
     struct wlr_seat                *seat;
     struct wlr_data_device_manager *data_device_mgr;
     struct wlr_xdg_shell           *xdg_shell;
+    /* Phase 64: XDG decoration manager — tell clients to use CSD */
+    struct wlr_xdg_decoration_manager_v1 *decoration_manager;
+    struct wl_listener              decoration_new_listener;
     /* Phase 36: XDG toplevel tracking */
     struct wl_listener              xdg_new_surface_listener;
     int                             managed_surface_count; /* surfaces seen */
@@ -306,6 +313,21 @@ handle_toplevel_destroy(struct wl_listener *listener, void *data)
     wfree(view);
 }
 
+/*
+ * Phase 64: new_toplevel_decoration listener.
+ * Immediately respond with CLIENT_SIDE so clients draw their own
+ * title bars and borders (the Wayland path has no X11 frame rendering).
+ */
+static void
+handle_new_toplevel_decoration(struct wl_listener *listener, void *data)
+{
+    struct wlr_xdg_toplevel_decoration_v1 *deco = data;
+    (void)listener;
+    wlr_xdg_toplevel_decoration_v1_set_mode(deco,
+        WLR_XDG_TOPLEVEL_DECORATION_V1_MODE_CLIENT_SIDE);
+    wwarning("wl_backend: decoration mode=client_side for new toplevel");
+}
+
 /*
  * Phase 36 / 38: new XDG surface listener.
  * Allocates a wl_toplevel_view, assigns a synthetic WNativeWindow ID,
@@ -428,6 +450,18 @@ wl_display_open(const char *name)
         wlr_data_device_manager_create(wl_state.display);
     wl_state.xdg_shell        = wlr_xdg_shell_create(wl_state.display);
 
+    /* Phase 64: advertise zxdg_decoration_manager_v1 so clients that
+     * support server-side decorations can negotiate; we respond with
+     * CLIENT_SIDE since the Wayland path has no X11 frame rendering. */
+    wl_state.decoration_manager =
+        wlr_xdg_decoration_manager_v1_create(wl_state.display);
+    if (wl_state.decoration_manager) {
+        wl_state.decoration_new_listener.notify = handle_new_toplevel_decoration;
+        wl_signal_add(&wl_state.decoration_manager->events.new_toplevel_decoration,
+                      &wl_state.decoration_new_listener);
+        wwarning("wl_backend: xdg-decoration-manager created");
+    }
+
     /* Phase 36: advertise wl_shm (needed by SHM buffer clients) and
      * expose the headless output as a wl_output global. */
     wlr_renderer_init_wl_shm(wl_state.renderer, wl_state.display);
diff --git a/tests/wl-smoke-test.sh b/tests/wl-smoke-test.sh
index 1da024c..37cc8a8 100755
--- a/tests/wl-smoke-test.sh
+++ b/tests/wl-smoke-test.sh
@@ -47,6 +47,9 @@
 #  21. (Phase 63) PropGetProtocols sets DELETE_WINDOW=1 for Wayland windows;
 #      wClientSendProtocol dispatches client_close so MC_CLOSE is enabled and
 #      polite close works; verified by wManageWindow logging kill_close=0.
+#  22. (Phase 64) zxdg_decoration_manager_v1 advertised in global registry;
+#      compositor logs "xdg-decoration-manager created"; new toplevels receive
+#      CLIENT_SIDE mode ("decoration mode=client_side" logged).
 #
 # This test grows as wl_backend vtable slots are implemented.
 #
@@ -151,6 +154,14 @@ PTR_POS=$(grep -o 'virtual pointer initialised at [0-9]*,[0-9]*' /tmp/wl-smoke-s
           | head -1 | sed 's/virtual pointer initialised at //')
 echo "  pointer check: virtual pointer initialised at $PTR_POS"
 
+# -- 4c. Phase 64: XDG decoration manager must be created ----------------
+#
+# wl_display_open() logs "xdg-decoration-manager created" when
+# wlr_xdg_decoration_manager_v1_create() succeeds.
+grep -q 'xdg-decoration-manager created' /tmp/wl-smoke-stderr \
+    || die "compositor did not log xdg-decoration-manager creation"
+echo "  decoration check: xdg-decoration-manager created"
+
 # -- 5. Core Wayland globals must be advertised ---------------------------
 #
 # Phase 35: wl_compositor, wl_seat, and xdg_wm_base must appear in the
@@ -172,7 +183,10 @@ if command -v weston-info >/dev/null 2>&1; then
     # Phase 53: seat must advertise pointer capability
     echo "$WI" | grep -q 'pointer' \
         || die "wl_seat does not advertise pointer capability"
-    echo "  globals check: wl_compositor, wl_seat, xdg_wm_base, wl_shm, wl_output present; seat has pointer capability"
+    # Phase 64: zxdg_decoration_manager_v1 must be in the global registry
+    echo "$WI" | grep -q 'zxdg_decoration_manager_v1' \
+        || die "zxdg_decoration_manager_v1 not in Wayland global registry"
+    echo "  globals check: wl_compositor, wl_seat, xdg_wm_base, wl_shm, wl_output, zxdg_decoration_manager_v1 present; seat has pointer capability"
 else
     echo "  globals check: skipped (weston-info not installed)"
 fi