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, 24 insertions, 2 deletions

diff --git a/src/config/model.rs b/src/config/model.rs
index 9bd83a96..16aa1d7d 100644
--- a/src/config/model.rs
+++ b/src/config/model.rs
@@ -5,8 +5,8 @@ use serde::{de, Deserialize, Deserializer, Serialize};
 
 use super::{
     ActionKeybinds, BindingConfig, CommandKeybindConfig, IndexedKeybind, Keybinds, SidebarConfig,
-    SoundConfig, ThemeConfig, DEFAULT_MOBILE_WIDTH_THRESHOLD, DEFAULT_MOUSE_SCROLL_LINES,
-    DEFAULT_SCROLLBACK_LIMIT_BYTES,
+    SoundConfig, TabBarRightEntryConfig, ThemeConfig, DEFAULT_MOBILE_WIDTH_THRESHOLD,
+    DEFAULT_MOUSE_SCROLL_LINES, DEFAULT_SCROLLBACK_LIMIT_BYTES,
 };
 
 pub const MAX_TOAST_DELAY_SECONDS: u64 = 3600;
@@ -874,6 +874,10 @@ pub struct UiConfig {
     pub hide_tab_bar_when_single_tab: bool,
     /// Desktop tab row placement. Default: top.
     pub tab_bar_position: TabBarPositionConfig,
+    /// Ordered entries shown at the right edge of the desktop tab row. Empty by default.
+    pub tab_bar_right: Vec<TabBarRightEntryConfig>,
+    /// Text inserted between visible right-side tab bar entries. Default: one space.
+    pub tab_bar_right_separator: String,
     /// Agent sidebar ordering. Saved values are "spaces" or "priority". Default: "spaces".
     pub agent_panel_sort: AgentPanelSortConfig,
     /// Retired setting that Herdr wrote before the workspace filter was removed.
@@ -1088,6 +1092,8 @@ impl Default for UiConfig {
             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(),
             agent_panel_sort: AgentPanelSortConfig::Spaces,
             _legacy_agent_panel_scope: None,
             status_indicators: StatusIndicatorStyle::Dots,
@@ -1344,6 +1350,8 @@ status_indicators = "symbols"
             default_config.ui.tab_bar_position,
             TabBarPositionConfig::Top
         );
+        assert!(default_config.ui.tab_bar_right.is_empty());
+        assert_eq!(default_config.ui.tab_bar_right_separator, " ");
 
         let toml = r#"
 [ui]
@@ -1354,6 +1362,14 @@ pane_gaps = true
 show_agent_labels_on_pane_borders = true
 hide_tab_bar_when_single_tab = true
 tab_bar_position = "bottom"
+tab_bar_right = [
+  { type = "zoom" },
+  { type = "hostname" },
+  { type = "datetime", format = "%H:%M" },
+  { type = "text", text = "prod" },
+  { type = "command", command = "status.sh", interval_seconds = 10, timeout_seconds = 3 },
+]
+tab_bar_right_separator = " · "
 "#;
         let config: Config = toml::from_str(toml).unwrap();
         assert!(!config.ui.pane_borders);
@@ -1363,6 +1379,12 @@ tab_bar_position = "bottom"
         assert!(config.ui.show_agent_labels_on_pane_borders);
         assert!(config.ui.hide_tab_bar_when_single_tab);
         assert_eq!(config.ui.tab_bar_position, TabBarPositionConfig::Bottom);
+        assert_eq!(config.ui.tab_bar_right.len(), 5);
+        assert!(matches!(
+            config.ui.tab_bar_right[1],
+            TabBarRightEntryConfig::Hostname
+        ));
+        assert_eq!(config.ui.tab_bar_right_separator, " · ");
     }
 
     #[test]