Replace the notification system with events. Events can carry a payload of

additional payload (to reduce problems with lifetime of objects) and are
delivered to one or more event sinks. This is more powerful and reduces the
complex dependencies between control mode and hooks. Events are now used for
hooks, control mode notifications and for monitors (set-hook -B).

wait-for can now wait for an event to fire (-E flag, with -F to for filter),
with -v to print the payload, as well as listing (-l) waiting clients on an
event and forcing one to wake (-w).

A few additional hooks are also now available (pane-created, pane-resized, etc)
and some of the existing ones have additional format variables available.

tmux.h

@@ -1,4 +1,4 @@
-/* $OpenBSD$ */
+/* $OpenBSD: tmux.h,v 1.1394 2026/07/10 13:38:45 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -48,6 +48,9 @@ struct cmdq_state;
 struct cmds;
 struct control_state;
 struct environ;
+struct event_payload;
+struct event_payload_item;
+struct events_sink;
 struct format_job_tree;
 struct format_tree;
 struct hyperlinks_uri;
@@ -2302,6 +2305,23 @@ struct monitor_change {
 };
 typedef void (*monitor_cb)(struct monitor_change *, void *);
 
+/* Event payload type. */
+enum event_payload_type {
+	EVENT_PAYLOAD_STRING,
+	EVENT_PAYLOAD_TIME,
+	EVENT_PAYLOAD_INT,
+	EVENT_PAYLOAD_UINT,
+	EVENT_PAYLOAD_CLIENT,
+	EVENT_PAYLOAD_SESSION,
+	EVENT_PAYLOAD_WINDOW,
+	EVENT_PAYLOAD_PANE,
+	EVENT_PAYLOAD_POINTER
+};
+
+/* Event payload callbacks. */
+typedef void (*event_payload_free_cb)(void *);
+typedef void (*event_payload_print_cb)(void *, struct evbuffer *);
+
 /* Key binding and key table. */
 struct key_binding {
 	key_code		 key;
@@ -2611,29 +2631,78 @@ char		*format_grid_hyperlink(struct grid *, u_int, u_int,
 		     struct screen *);
 char		*format_grid_line(struct grid *, u_int);
 
-/* format-draw.c */
-void		 format_draw(struct screen_write_ctx *,
-		     const struct grid_cell *, u_int, const char *,
-		     struct style_ranges *, int);
-u_int		 format_width(const char *);
-char		*format_trim_left(const char *, u_int);
-char		*format_trim_right(const char *, u_int);
+/* events-payload.c */
+struct event_payload *event_payload_create(void);
+void	 event_payload_free(struct event_payload *);
+void printflike(2, 3) event_payload_log(struct event_payload *, const char *,
+	     ...);
+char	*event_payload_item_print(struct event_payload_item *);
+void	 event_payload_set_target(struct event_payload *,
+	     struct cmd_find_state *);
+int	 event_payload_get_target(struct event_payload *,
+	     struct cmd_find_state *);
+void printflike(3, 4) event_payload_set_string(struct event_payload *,
+	     const char *, const char *, ...);
+void	 event_payload_set_time(struct event_payload *, const char *, time_t);
+void	 event_payload_set_int(struct event_payload *, const char *, int);
+void	 event_payload_set_uint(struct event_payload *, const char *, u_int);
+void	 event_payload_set_client(struct event_payload *, const char *,
+	     struct client *);
+void	 event_payload_set_session(struct event_payload *, const char *,
+	     struct session *);
+void	 event_payload_set_window(struct event_payload *, const char *,
+	     struct window *);
+void	 event_payload_set_pane(struct event_payload *, const char *,
+	     struct window_pane *);
+void	 event_payload_set_pointer(struct event_payload *, const char *, void *,
+	     event_payload_free_cb, event_payload_print_cb);
+const char *event_payload_get_string(struct event_payload *, const char *);
+char	*event_payload_print(struct event_payload *, const char *);
+void	 event_payload_add_formats(struct event_payload *,
+	     struct format_tree *, const char *);
+struct event_payload_item *event_payload_first(struct event_payload *);
+struct event_payload_item *event_payload_next(struct event_payload_item *);
+const char *event_payload_item_name(struct event_payload_item *);
+enum event_payload_type event_payload_item_type(struct event_payload_item *);
+time_t	 event_payload_get_time(struct event_payload *, const char *);
+int	 event_payload_get_int(struct event_payload *, const char *, int *);
+int	 event_payload_get_uint(struct event_payload *, const char *, u_int *);
+struct client *event_payload_get_client(struct event_payload *, const char *);
+struct session *event_payload_get_session(struct event_payload *, const char *);
+struct window *event_payload_get_window(struct event_payload *, const char *);
+struct window_pane *event_payload_get_pane(struct event_payload *,
+	     const char *);
+void	*event_payload_get_pointer(struct event_payload *, const char *);
 
-/* notify.c */
-void	notify_hook(struct cmdq_item *, const char *);
-void	notify_monitor_add(struct cmdq_item *, struct options *,
+/* events.c */
+typedef void (*events_cb)(const char *, struct event_payload *, void *);
+struct events_sink *events_add_sink(const char *, events_cb, void *);
+void	 events_remove_sink(struct events_sink *);
+void	 events_fire(const char *, struct event_payload *);
+void	 events_fire_client(const char *, struct client *);
+void	 events_fire_session(const char *, struct session *);
+void	 events_fire_window(const char *, struct window *);
+void	 events_fire_pane(const char *, struct window_pane *);
+void	 events_fire_winlink(const char *, struct winlink *);
+
+/* format-draw.c */
+void	 format_draw(struct screen_write_ctx *, const struct grid_cell *,
+	     u_int, const char *, struct style_ranges *, int);
+u_int	 format_width(const char *);
+char	*format_trim_left(const char *, u_int);
+char	*format_trim_right(const char *, u_int);
+
+/* hooks.c */
+void	 hooks_add_event(const char *);
+int	 hooks_valid_event_name(const char *);
+void	 hooks_build_events(void);
+void	 hooks_run(struct cmdq_item *, const char *);
+void	 hooks_monitor_add(struct cmdq_item *, struct options *,
 	    const char *, enum monitor_type, int, const char *,
 	    struct cmd_find_state *, struct session *);
-void	notify_monitor_remove(struct options *, const char *);
-void	notify_monitor_free(void *);
-char	*notify_monitor_to_string(struct options_entry *);
-void	notify_client(const char *, struct client *);
-void	notify_session(const char *, struct session *);
-void	notify_winlink(const char *, struct winlink *);
-void	notify_session_window(const char *, struct session *, struct window *);
-void	notify_window(const char *, struct window *);
-void	notify_pane(const char *, struct window_pane *);
-void	notify_paste_buffer(const char *, int);
+void	 hooks_monitor_remove(struct options *, const char *);
+void	 hooks_monitor_free(void *);
+char	*hooks_monitor_to_string(struct options_entry *);
 
 /* options.c */
 struct options	*options_create(struct options *);
@@ -3855,20 +3924,7 @@ void	control_add_sub(struct client *, const char *, enum monitor_type, int,
 void	control_remove_sub(struct client *, const char *);
 
 /* control-notify.c */
-void	control_notify_pane_mode_changed(int);
-void	control_notify_window_layout_changed(struct window *);
-void	control_notify_window_pane_changed(struct window *);
-void	control_notify_window_unlinked(struct session *, struct window *);
-void	control_notify_window_linked(struct session *, struct window *);
-void	control_notify_window_renamed(struct window *);
-void	control_notify_client_session_changed(struct client *);
-void	control_notify_client_detached(struct client *);
-void	control_notify_session_renamed(struct session *);
-void	control_notify_session_created(struct session *);
-void	control_notify_session_closed(struct session *);
-void	control_notify_session_window_changed(struct session *);
-void	control_notify_paste_buffer_changed(const char *);
-void	control_notify_paste_buffer_deleted(const char *);
+void	control_build_events(void);
 
 /* session.c */
 extern struct sessions sessions;