Extend client mode so the preview can be changed to a view with a

summary of the client terminal and its features, intended to make
troubleshooting easier. "choose-client -i" or the "i" key in the mode.

usr.bin/tmux/cmd-choose-tree.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: cmd-choose-tree.c,v 1.55 2026/06/08 21:01:33 nicm Exp $ */
+/* $OpenBSD: cmd-choose-tree.c,v 1.56 2026/06/13 10:32:54 nicm Exp $ */
 
 /*
  * Copyright (c) 2012 Thomas Adam <thomas@xteddy.org>
@@ -47,8 +47,8 @@ const struct cmd_entry cmd_choose_client_entry = {
 	.name = "choose-client",
 	.alias = NULL,
 
-	.args = { "F:f:hK:kNO:rt:yZ", 0, 1, cmd_choose_tree_args_parse },
-	.usage = "[-hkNrZ] [-F format] [-f filter] [-K key-format] "
+	.args = { "F:f:hiK:kNO:rt:yZ", 0, 1, cmd_choose_tree_args_parse },
+	.usage = "[-hikNrZ] [-F format] [-f filter] [-K key-format] "
 		 "[-O sort-order] " CMD_TARGET_PANE_USAGE " [template]",
 
 	.target = { 't', CMD_FIND_PANE, 0 },

usr.bin/tmux/mode-tree.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: mode-tree.c,v 1.83 2026/06/08 15:16:21 nicm Exp $ */
+/* $OpenBSD: mode-tree.c,v 1.84 2026/06/13 10:32:54 nicm Exp $ */
 
 /*
  * Copyright (c) 2017 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -49,6 +49,7 @@ struct mode_tree_data {
 	const struct menu_item	 *menu;
 
 	struct sort_criteria	  sort_crit;
+	const char		 *view_name;
 
 	mode_tree_build_cb        buildcb;
 	mode_tree_draw_cb         drawcb;
@@ -700,6 +701,12 @@ mode_tree_add(struct mode_tree_data *mtd, struct mode_tree_item *parent,
 	return (mti);
 }
 
+void
+mode_tree_view_name(struct mode_tree_data *mtd, const char *name)
+{
+	mtd->view_name = name;
+}
+
 void
 mode_tree_draw_as_parent(struct mode_tree_item *mti)
 {
@@ -884,9 +891,12 @@ mode_tree_draw(struct mode_tree_data *mtd)
 	screen_write_box(&ctx, w, sy - h, BOX_LINES_DEFAULT, NULL, NULL);
 
 	if (mtd->sort_crit.order_seq != NULL) {
-		xasprintf(&text, " %s (sort: %s%s)", mti->name,
+		xasprintf(&text, " %s (sort: %s%s)%s%s%s", mti->name,
 		    sort_order_to_string(mtd->sort_crit.order),
-		    mtd->sort_crit.reversed ? ", reversed" : "");
+		    mtd->sort_crit.reversed ? ", reversed" : "",
+		    mtd->view_name == NULL ? "" : " (view: ",
+		    mtd->view_name == NULL ? "" : mtd->view_name,
+		    mtd->view_name == NULL ? "" : ")");
 	} else
 		xasprintf(&text, " %s", mti->name);
 	if (w - 2 >= strlen(text)) {

usr.bin/tmux/tmux.1

@@ -1,4 +1,4 @@
-.\" $OpenBSD: tmux.1,v 1.1082 2026/06/13 09:17:29 nicm Exp $
+.\" $OpenBSD: tmux.1,v 1.1083 2026/06/13 10:32:54 nicm Exp $
 .\"
 .\" Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
 .\"
@@ -2864,7 +2864,7 @@ The
 command works only if at least one client is attached.
 .It Xo
 .Ic choose\-tree
-.Op Fl GhkNrswyZ
+.Op Fl GhikNrswyZ
 .Op Fl F Ar format
 .Op Fl f Ar filter
 .Op Fl K Ar key\-format
@@ -2916,6 +2916,7 @@ The following keys may be used in tree mode:
 .It Li "O" Ta "Change sort order"
 .It Li "r" Ta "Reverse sort order"
 .It Li "v" Ta "Toggle preview"
+.It Li "i" Ta "Change view (preview and client information)"
 .It Li "F1 or C\-h" Ta "Display help"
 .It Li "q" Ta "Exit mode"
 .El
@@ -2955,6 +2956,8 @@ first.
 .Pp
 .Fl N
 starts without the preview or if given twice with the larger preview.
+.Fl i
+starts showing client information instead of the preview.
 .Fl h
 hides the pane containing the mode.
 .Fl k

usr.bin/tmux/tmux.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: tmux.h,v 1.1347 2026/06/13 09:17:29 nicm Exp $ */
+/* $OpenBSD: tmux.h,v 1.1348 2026/06/13 10:32:54 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -3565,6 +3565,7 @@ void	 mode_tree_resize(struct mode_tree_data *, u_int, u_int);
 struct mode_tree_item *mode_tree_add(struct mode_tree_data *,
 	     struct mode_tree_item *, void *, uint64_t, const char *,
 	     const char *, int);
+void	 mode_tree_view_name(struct mode_tree_data *, const char *);
 void	 mode_tree_draw_as_parent(struct mode_tree_item *);
 void	 mode_tree_no_tag(struct mode_tree_item *);
 void	 mode_tree_align(struct mode_tree_item *, int);
@@ -3606,7 +3607,7 @@ int		 window_copy_get_current_offset(struct window_pane *, u_int *,
 char		*window_copy_get_hyperlink(struct window_pane *, u_int, u_int);
 void		 window_copy_set_line_numbers(struct window_pane *, int);
 
-/* window-option.c */
+/* window-customize.c */
 extern const struct window_mode window_customize_mode;
 
 /* names.c */

usr.bin/tmux/window-client.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: window-client.c,v 1.39 2026/06/08 21:01:33 nicm Exp $ */
+/* $OpenBSD: window-client.c,v 1.40 2026/06/13 10:32:54 nicm Exp $ */
 
 /*
  * Copyright (c) 2017 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -47,6 +47,93 @@ static void		 window_client_key(struct window_mode_entry *,
 		"M-#{a:#{e|+:97,#{e|-:#{line},10}}}" \
 	"}"
 
+#define WINDOW_CLIENT_FEATURE(f) \
+	"#{?#{I/f:" #f "}," \
+	"#[fg=green],#[dim]}#{p/15:#{l:" #f "}}" \
+	"#[default]"
+static const char *window_client_info_lines[] = {
+	"Client Name   #[acs]x#[default] "
+	"#{client_name} "
+	"#[dim](PID #{client_pid})#[default]",
+	"Session       #[acs]x#[default] "
+	"#{session_name}",
+	"Attach Time   #[acs]x#[default] "
+	"#{t:client_created} "
+	"#[dim](#{t/r:client_created})#[default]",
+	"Activity Time #[acs]x#[default] "
+	"#{t:client_created} "
+	"#[dim](#{t/r:client_created})#[default]",
+	"Terminal Type #[acs]x#[default] "
+	"#{?client_termtype,#{client_termtype},Unknown}",
+	"TERM          #[acs]x#[default] "
+	"#{client_termname}",
+	"Size          #[acs]x#[default] "
+	"#{client_width}x#{client_height} "
+	"#[dim](cell #{client_cell_width}x#{client_cell_height})#[default]",
+	"Bytes Written #[acs]x#[default] "
+	"#{client_written} "
+	"#[dim](#{client_discarded} discarded)#[default]",
+
+	"Features      #[acs]x#[default] "
+	WINDOW_CLIENT_FEATURE(256) " "
+	WINDOW_CLIENT_FEATURE(RGB) " "
+	WINDOW_CLIENT_FEATURE(bpaste) " "
+	WINDOW_CLIENT_FEATURE(ccolour),
+	"              #[acs]x#[default] "
+	WINDOW_CLIENT_FEATURE(clipboard) " "
+	WINDOW_CLIENT_FEATURE(cstyle) " "
+	WINDOW_CLIENT_FEATURE(extkeys) " "
+	WINDOW_CLIENT_FEATURE(focus),
+	"              #[acs]x#[default] "
+	WINDOW_CLIENT_FEATURE(hyperlinks) " "
+	WINDOW_CLIENT_FEATURE(ignorefkeys) " "
+	WINDOW_CLIENT_FEATURE(margins) " "
+	WINDOW_CLIENT_FEATURE(mouse),
+	"              #[acs]x#[default] "
+	WINDOW_CLIENT_FEATURE(osc7) " "
+	WINDOW_CLIENT_FEATURE(overline) " "
+	WINDOW_CLIENT_FEATURE(progressbar) " "
+	WINDOW_CLIENT_FEATURE(rectfill),
+	"              #[acs]x#[default] "
+	WINDOW_CLIENT_FEATURE(sixel) " "
+	WINDOW_CLIENT_FEATURE(strikethrough) " "
+	WINDOW_CLIENT_FEATURE(sync) " "
+	WINDOW_CLIENT_FEATURE(title),
+	"              #[acs]x#[default] "
+	WINDOW_CLIENT_FEATURE(usstyle),
+	"#[acs]qqqqqqqqqqqqqqn#{R:q,#{window_width}}#[default]",
+
+	"prefix        #[acs]x#[default] "
+	"#{prefix}",
+
+	"mouse         #[acs]x#[default] "
+	"#{?mouse,#{?#{I/c:kmous},,#[fg=red]}on,#[dim]off} "
+	"#{?#{I/c:kmous},,#[align=right]unavailable: [kmous] missing}",
+
+	"set-clipboard #[acs]x#[default] "
+	"#{?#{!=:#{set-clipboard},off},#{?#{I/f:clipboard},,#[fg=red]}#{set-clipboard},#[dim]off} "
+	"#{?#{I/f:clipboard},,#[align=right]unavailable: [Ms] missing}",
+
+	"get-clipboard #[acs]x#[default] "
+	"#{?#{!=:#{get-clipboard},off},#{?#{I/f:clipboard},,#[fg=red]}#{get-clipboard},#[dim]off} "
+	"#{?#{I/f:clipboard},,#[align=right]unavailable: [Ms] missing}",
+
+	"focus-events  #[acs]x#[default] "
+	"#{?focus-events,#{?#{I/f:focus},,#[fg=red]}on,#[dim]off} "
+	"#{?#{I/f:focus},,#[align=right]unavailable: [Enfcs] or [Dcfcs] missing}",
+
+	"extended-keys #[acs]x#[default] "
+	"#{?#{!=:#{extended-keys},off},#{?#{I/f:extkeys},,#[fg=red]}#{extended-keys},#[dim]off} "
+	"#{?#{I/f:extkeys},,#[align=right]unavailable: [Eneks] or [Dseks] missing}",
+
+	"set-titles    #[acs]x#[default] "
+	"#{?set-titles,on,#[dim]off}",
+
+	"escape-time   #[acs]x#[default] "
+	"#{escape-time} ms",
+};
+
+
 static const struct menu_item window_client_menu_items[] = {
 	{ "Detach", 'd', NULL },
 	{ "Detach Tagged", 'D', NULL },
@@ -82,7 +169,9 @@ struct window_client_modedata {
 	char				 *format;
 	char				 *key_format;
 	char				 *command;
+
 	int				  hide_preview_this_pane;
+	int				  preview_is_info;
 
 	struct window_client_itemdata	**item_list;
 	u_int				  item_size;
@@ -162,6 +251,32 @@ window_client_build(void *modedata, struct sort_criteria *sort_crit,
 	}
 }
 
+static void
+window_client_draw_info(__unused void *modedata, void *itemdata,
+    struct screen_write_ctx *ctx, u_int sx, u_int sy)
+{
+	struct window_client_itemdata	*item = itemdata;
+	struct client			*c = item->c;
+	struct screen			*s = ctx->s;
+	u_int				 cx = s->cx, cy = s->cy, i;
+	struct format_tree		*ft;
+	char				*expanded;
+
+	ft = format_create_defaults(NULL, c, NULL, NULL, NULL);
+
+	screen_write_cursormove(ctx, cx, cy, 0);
+	for (i = 0; i < nitems(window_client_info_lines); i++) {
+		if (i == sy)
+			break;
+		expanded = format_expand(ft, window_client_info_lines[i]);
+		screen_write_cursormove(ctx, cx, cy + i, 0);
+		format_draw(ctx, &grid_default_cell, sx, expanded, NULL, 0);
+		free(expanded);
+	}
+
+	format_free(ft);
+}
+
 static void
 window_client_draw(void *modedata, void *itemdata,
     struct screen_write_ctx *ctx, u_int sx, u_int sy)
@@ -175,6 +290,10 @@ window_client_draw(void *modedata, void *itemdata,
 
 	if (c->session == NULL || (c->flags & CLIENT_UNATTACHEDFLAGS))
 		return;
+	if (data->preview_is_info) {
+		window_client_draw_info(modedata, itemdata, ctx, sx, sy);
+		return;
+	}
 	wp = c->session->curw->window->active;
 	if (data->hide_preview_this_pane && wp == data->wp) {
 		if (!TAILQ_EMPTY(&c->session->curw->window->last_panes))
@@ -250,6 +369,7 @@ window_client_sort(struct sort_criteria *sort_crit)
 }
 
 static const char* window_client_help_lines[] = {
+	"\r\033[1m          i \033[0m\016x\017 \033[0mToggle info view\n",
 	"\r\033[1m      Enter \033[0m\016x\017 \033[0mChoose selected %1\n",
 	"\r\033[1m          d \033[0m\016x\017 \033[0mDetach selected %1\n",
 	"\r\033[1m          D \033[0m\016x\017 \033[0mDetach tagged %1s\n",
@@ -280,6 +400,7 @@ window_client_init(struct window_mode_entry *wme,
 	wme->data = data = xcalloc(1, sizeof *data);
 	data->wp = wp;
 	data->hide_preview_this_pane = args != NULL && args_has(args, 'h');
+	data->preview_is_info = args != NULL && args_has(args, 'i');
 
 	if (args == NULL || !args_has(args, 'F'))
 		data->format = xstrdup(WINDOW_CLIENT_DEFAULT_FORMAT);
@@ -300,6 +421,11 @@ window_client_init(struct window_mode_entry *wme,
 	    window_client_help, data, window_client_menu_items, &s);
 	mode_tree_zoom(data->data, args);
 
+	if (data->preview_is_info)
+		mode_tree_view_name(data->data, "info");
+	else
+		mode_tree_view_name(data->data, "preview");
+
 	mode_tree_build(data->data);
 	mode_tree_draw(data->data);
 
@@ -389,6 +515,14 @@ window_client_key(struct window_mode_entry *wme, struct client *c,
 		mode_tree_each_tagged(mtd, window_client_do_detach, c, key, 0);
 		mode_tree_build(mtd);
 		break;
+	case 'i':
+		data->preview_is_info = !data->preview_is_info;
+		if (data->preview_is_info)
+			mode_tree_view_name(mtd, "info");
+		else
+			mode_tree_view_name(mtd, "preview");
+		mode_tree_build(mtd);
+		break;
 	case '\r':
 		item = mode_tree_get_current(mtd);
 		mode_tree_run_command(c, NULL, data->command, item->c->ttyname);