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, 10 insertions, 0 deletions

diff --git a/src/app/state.rs b/src/app/state.rs
index e460f62b..cbecef00 100644
--- a/src/app/state.rs
+++ b/src/app/state.rs
@@ -1317,6 +1317,12 @@ pub(crate) struct PaneFocusTarget {
 
 /// All application state — pure data, no channels or async runtime.
 /// Testable without PTYs or a tokio runtime.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum TabBarStatusSegment {
+    Zoom,
+    Text(Option<String>),
+}
+
 pub struct AppState {
     pub terminals:
         std::collections::HashMap<crate::terminal::TerminalId, crate::terminal::TerminalState>,
@@ -1432,6 +1438,8 @@ pub struct AppState {
     pub show_agent_labels_on_pane_borders: bool,
     pub hide_tab_bar_when_single_tab: bool,
     pub tab_bar_position: TabBarPositionConfig,
+    pub tab_bar_right: Vec<TabBarStatusSegment>,
+    pub tab_bar_right_separator: String,
     pub pane_history_persistence: bool,
     /// Expose the focused pane's cursor anchor to the outer terminal even when
     /// the pane requested `?25l`. See `[experimental] reveal_hidden_cursor_for_cjk_ime`.
@@ -1798,6 +1806,8 @@ impl AppState {
             show_agent_labels_on_pane_borders: false,
             hide_tab_bar_when_single_tab: false,
             tab_bar_position: TabBarPositionConfig::Top,
+            tab_bar_right: Vec::new(),
+            tab_bar_right_separator: " ".into(),
             pane_history_persistence: false,
             reveal_hidden_cursor_for_cjk_ime: false,
             cjk_ime_agent_filter_configured: false,