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>

2 files changed, 23 insertions, 2 deletions

diff --git a/scripts/config_reference_check.py b/scripts/config_reference_check.py
index f9aa5e72..c23b284b 100644
--- a/scripts/config_reference_check.py
+++ b/scripts/config_reference_check.py
@@ -35,7 +35,9 @@ SKIPPED_SUBTREES = ("keys.command",)
 FIELD_RE = re.compile(r"^\s*pub ([a-z_][a-z0-9_]*):\s*(.+?),?\s*$")
 STRUCT_RE = re.compile(r"^\s*pub(?:\(crate\))? struct ([A-Za-z0-9_]+)\s*\{\s*$")
 ENUM_RE = re.compile(r"^\s*pub(?:\(crate\))? enum ([A-Za-z0-9_]+)\s*\{\s*$")
-VARIANT_RE = re.compile(r"^\s*([A-Z][A-Za-z0-9_]*)\s*(?:\(.*\))?\s*,?\s*$")
+VARIANT_RE = re.compile(
+    r"^\s*([A-Z][A-Za-z0-9_]*)\s*(?:\(.*\)|\{)?\s*,?\s*$"
+)
 RENAME_ALL_RE = re.compile(r'rename_all\s*=\s*"([^"]+)"')
 RENAME_RE = re.compile(r'rename\s*=\s*"([^"]+)"')
 
@@ -190,11 +192,11 @@ def parse_enum_body(
             index += 1
             break
 
-        depth += stripped.count("{") - stripped.count("}")
         if depth == 0 and not stripped.startswith(("#[", "///")):
             match = VARIANT_RE.match(stripped)
             if match:
                 variants.append(apply_rename_all(match.group(1), rename_all or "lowercase"))
+        depth += stripped.count("{") - stripped.count("}")
         index += 1
 
     model.enums[name] = variants
diff --git a/scripts/test_config_reference_check.py b/scripts/test_config_reference_check.py
index 317aae8a..b5a804b1 100644
--- a/scripts/test_config_reference_check.py
+++ b/scripts/test_config_reference_check.py
@@ -32,6 +32,8 @@ pub struct UiConfig {
     pub sidebar_width: u16,
     /// Host cursor policy. Default: auto.
     pub host_cursor: HostCursorModeConfig,
+    /// Tab bar status entries.
+    pub tab_bar_right: Vec<TabBarRightEntryConfig>,
     #[serde(rename = "accent_color")]
     pub accent: String,
     #[serde(skip)]
@@ -64,6 +66,19 @@ pub enum HostCursorModeConfig {
 }
 
 #[derive(Debug, Deserialize)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum TabBarRightEntryConfig {
+    Hostname,
+    Datetime {
+        format: String,
+    },
+    Command {
+        command: String,
+        interval_seconds: u64,
+    },
+}
+
+#[derive(Debug, Deserialize)]
 #[serde(untagged)]
 pub enum BindingConfig {
     One(String),
@@ -129,6 +144,10 @@ class CollectKeysTests(unittest.TestCase):
         self.assertEqual(
             entries["ui.host_cursor"]["values"], ["auto", "native-cursor", "drawn"]
         )
+        self.assertEqual(
+            entries["ui.tab_bar_right"]["values"],
+            ["hostname", "datetime", "command"],
+        )
         self.assertNotIn("values", entries["keys.zoom"])