feat: add configurable tab bar status (#2586)

* feat: show a zoom indicator in the desktop tab bar

Reserve the right edge of the tab row for a ZOOM pill while the
focused pane is zoomed, matching the accent style of the mode bars.
The per-tab Z suffix stays; the pill makes the zoomed state visible
at a glance like tmux's status-right flag.

* feat: optionally show the hostname in the desktop tab bar

Add ui.tab_bar_hostname to display the machine's hostname at the right
edge of the tab row, like tmux's #h in status-right. The value resolves
where the server renders, so remote sessions show the remote host. Off
by default.

* fix: strip control characters from the tab bar hostname

* fix: hide the hostname when it would squeeze out the tab strip

* feat: add configurable tab bar status

* fix: harden tab bar status updates

* fix: terminate tab bar status process trees

* fix: disable status commands on unsupported platforms

* fix: skip unchanged status command renders

* fix: keep tab bar status opt-in by default

---------

Co-authored-by: David Heinemeier Hansson <david@hey.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/src/platform/fallback.rs b/src/platform/fallback.rs
index f6380df8..2086e2a7 100644
--- a/src/platform/fallback.rs
+++ b/src/platform/fallback.rs
@@ -89,6 +89,28 @@ pub(crate) fn should_draw_host_cursor_by_default() -> bool {
     false
 }
 
+pub(crate) fn hostname() -> Option<String> {
+    None
+}
+
+pub(crate) fn local_datetime() -> Option<time::PrimitiveDateTime> {
+    None
+}
+
+pub(crate) fn status_commands_supported() -> bool {
+    false
+}
+
+pub(crate) fn configure_status_command(_process: &mut std::process::Command) {}
+
+pub(crate) struct StatusCommandGuard;
+
+impl StatusCommandGuard {
+    pub(crate) fn new(_child: &tokio::process::Child) -> std::io::Result<Self> {
+        Ok(Self)
+    }
+}
+
 fn raw_command_argv(command: &str, flag: &str) -> Vec<std::ffi::OsString> {
     vec!["/bin/sh".into(), flag.into(), command.into()]
 }