wayland: Phase 46 — client_close vtable; title updates; protocol guards

Add client_close vtable slot to WMBackend:
  - x11: XKillClient + XFlush
  - wl: wlr_xdg_toplevel_send_close (politely asks client to close)
  - wClientKill: use wm_backend->client_close() for Wayland path

Guard wClientSendProtocol with if (!dpy) return so it is safe to call
on Wayland windows (protocols.DELETE_WINDOW is always 0 for Wayland).

Wire XDG toplevel set_title signal: add title_listener to
wl_toplevel_view; handle_toplevel_title updates wwin->wm_class /
wm_instance when the client changes its title, and calls
wWindowUpdateName (which no-ops on frameless windows but posts
WMNChangedName when a frame is present).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/backend/backend.h

@@ -811,6 +811,12 @@ typedef struct WMBackend {
      */
     void (*client_remove_from_save_set)(WNativeWindow win);
 
+    /*
+     * Request a client window to close itself.
+     * On X11: XKillClient (forceful); on Wayland: xdg_toplevel_send_close.
+     */
+    void (*client_close)(WNativeWindow win);
+
     /* ------------------------------------------------------------------ */
     /* Fake group-leader window  (Phase 13)                               */
     /* ------------------------------------------------------------------ */

src/backend/wayland/wl_backend.c

@@ -27,6 +27,9 @@
  * so clients receive size changes from the WM.
  * Phase 45: pointer_query returns 1 (always on-screen); wWindowFocus/Unfocus
  * guarded on frame!=NULL so wSetFocusTo works without a frame window.
+ * Phase 46: client_close vtable slot (wlr_xdg_toplevel_send_close);
+ * title_listener updates wwin->wm_instance/wm_class on set_title signal;
+ * wClientSendProtocol/wClientKill guarded for Wayland.
  */
 
 #ifdef HAVE_CONFIG_H
@@ -75,6 +78,7 @@ struct wl_toplevel_view {
     struct wl_listener       map_listener;
     struct wl_listener       unmap_listener;
     struct wl_listener       destroy_listener;
+    struct wl_listener       title_listener;    /* Phase 46: xdg_toplevel set_title */
     WNativeWindow            id;           /* synthetic handle, >= 0x10000000 */
     struct wl_list           link;         /* wl_state.toplevel_list */
 };
@@ -159,6 +163,34 @@ wl_find_view_by_id(WNativeWindow id)
     return NULL;
 }
 
+/*
+ * Phase 46: XDG toplevel title changed — update wwin->wm_instance.
+ */
+static void
+handle_toplevel_title(struct wl_listener *listener, void *data)
+{
+    struct wl_toplevel_view *view = VIEW_FROM_LISTENER(listener, title_listener);
+    (void)data;
+    const char *new_title = view->xdg_surface->toplevel->title;
+
+    WObjDescriptor *desc = wm_backend->context_find(view->id, WM_CTX_CLIENT_WIN);
+    if (!desc || desc->parent_type != WCLASS_WINDOW)
+        return;
+    WWindow *wwin = (WWindow *)desc->parent;
+
+    if (wwin->wm_instance)
+        wfree(wwin->wm_instance);
+    wwin->wm_instance = new_title ? strdup(new_title) : NULL;
+
+    if (wwin->wm_class)
+        wfree(wwin->wm_class);
+    const char *app_id = (view->xdg_surface->toplevel->app_id)
+                         ? view->xdg_surface->toplevel->app_id : "wayland-client";
+    wwin->wm_class = strdup(app_id);
+
+    wWindowUpdateName(wwin, new_title);
+}
+
 /*
  * Phase 38: toplevel map — surface is ready to be managed.
  */
@@ -226,6 +258,7 @@ handle_toplevel_destroy(struct wl_listener *listener, void *data)
     wl_list_remove(&view->map_listener.link);
     wl_list_remove(&view->unmap_listener.link);
     wl_list_remove(&view->destroy_listener.link);
+    wl_list_remove(&view->title_listener.link);
     wl_list_remove(&view->link);
     wl_state.managed_surface_count--;
     wfree(view);
@@ -254,10 +287,12 @@ handle_xdg_new_surface(struct wl_listener *listener, void *data)
     view->map_listener.notify     = handle_toplevel_map;
     view->unmap_listener.notify   = handle_toplevel_unmap;
     view->destroy_listener.notify = handle_toplevel_destroy;
+    view->title_listener.notify   = handle_toplevel_title;
 
-    wl_signal_add(&xdg_surface->events.map,     &view->map_listener);
-    wl_signal_add(&xdg_surface->events.unmap,   &view->unmap_listener);
-    wl_signal_add(&xdg_surface->events.destroy, &view->destroy_listener);
+    wl_signal_add(&xdg_surface->events.map,                  &view->map_listener);
+    wl_signal_add(&xdg_surface->events.unmap,                &view->unmap_listener);
+    wl_signal_add(&xdg_surface->events.destroy,              &view->destroy_listener);
+    wl_signal_add(&xdg_surface->toplevel->events.set_title,  &view->title_listener);
 
     wl_list_insert(&wl_state.toplevel_list, &view->link);
     wl_state.managed_surface_count++;
@@ -864,6 +899,15 @@ wl_client_synth_configure(WNativeWindow client_win,
 static void wl_client_add_to_save_set(WNativeWindow win) { (void)win; }
 static void wl_client_remove_from_save_set(WNativeWindow win) { (void)win; }
 
+static void
+wl_client_close(WNativeWindow win)
+{
+    /* Phase 46: ask the XDG toplevel to close itself. */
+    struct wl_toplevel_view *v = wl_find_view_by_id(win);
+    if (v && v->xdg_surface)
+        wlr_xdg_toplevel_send_close(v->xdg_surface);
+}
+
 static void wl_client_query_shaped(WNativeWindow win, int *shaped_out)
 { (void)win; *shaped_out = 0; }
 
@@ -1101,6 +1145,7 @@ const WMBackend wl_backend = {
     .client_synth_configure = wl_client_synth_configure,
     .client_add_to_save_set = wl_client_add_to_save_set,
     .client_remove_from_save_set = wl_client_remove_from_save_set,
+    .client_close           = wl_client_close,
     .client_query_shaped    = wl_client_query_shaped,
     .client_get_gnustep_attrs = wl_client_get_gnustep_attrs,
     .client_get_pid         = wl_client_get_pid,

src/backend/x11/x11_backend.c

@@ -963,6 +963,13 @@ x11_client_remove_from_save_set(WNativeWindow win)
     XRemoveFromSaveSet(dpy, WNW_TO_XID(win));
 }
 
+static void
+x11_client_close(WNativeWindow win)
+{
+    XKillClient(dpy, WNW_TO_XID(win));
+    XFlush(dpy);
+}
+
 /* -------------------------------------------------------------------- */
 /* Fake group-leader window  (Phase 13)                                  */
 /* -------------------------------------------------------------------- */
@@ -2458,6 +2465,7 @@ const WMBackend x11_backend = {
     .client_reparent         = x11_client_reparent,
     .client_add_to_save_set  = x11_client_add_to_save_set,
     .client_remove_from_save_set = x11_client_remove_from_save_set,
+    .client_close            = x11_client_close,
     .fake_leader_create      = x11_fake_leader_create,
     .fake_leader_destroy     = x11_fake_leader_destroy,
     .icccm_set_class_hint    = x11_icccm_set_class_hint,

src/client.c

@@ -250,6 +250,9 @@ void wClientSendProtocol(WWindow * wwin, Atom protocol, Time time)
 {
 	XEvent event;
 
+	if (!dpy)
+		return; /* Wayland: no X11 ClientMessage */
+
 	event.xclient.type = ClientMessage;
 	event.xclient.message_type = w_global.atom.wm.protocols;
 	event.xclient.format = 32;
@@ -265,6 +268,11 @@ void wClientSendProtocol(WWindow * wwin, Atom protocol, Time time)
 
 void wClientKill(WWindow * wwin)
 {
+	if (!dpy) {
+		/* Wayland: request close via vtable */
+		wm_backend->client_close(wwin->client_win);
+		return;
+	}
 	XKillClient(dpy, wwin->client_win);
 
 	XFlush(dpy);