fix(panel): size the Session label column to the labels it holds

The key column was a hardcoded 46px, which fits "cwd" and "shell" and
little else. In English "changes" folded mid-word into "change / s". In
Chinese and Japanese almost every label wrapped — ja "作業ディレクトリ" is
eight glyphs in a column sized for three ASCII characters.

It now measures the labels actually on screen through the text system and
takes the widest, clamped to 46–108px so one long Japanese label cannot
eat the panel. The labels are `whitespace_nowrap`, so anything past the
clamp runs into the gap rather than folding.

Checked on screen in English and Chinese: "changes" and "工作目录" each sit
on one line, and the values still line up.

src/ui/right_panel.rs

@@ -38,6 +38,54 @@ pub(crate) struct RightPanelState {
 
 const PROCS_POLL: std::time::Duration = std::time::Duration::from_millis(2000);
 
+/// Widest of the labels actually on screen, so the values line up without a
+/// fixed width guessing at them.
+///
+/// A hardcoded 46px fitted "cwd" and "shell" and nothing else: English
+/// "changes" wrapped mid-word to "change / s", and in Chinese and Japanese
+/// almost every label wrapped — ja "作業ディレクトリ" is eight glyphs. The
+/// clamp keeps the longest of those from eating the panel; anything past it
+/// runs into the gap rather than folding, which `whitespace_nowrap` on the
+/// label guarantees.
+fn info_label_column(
+    rows: &[(&'static str, String)],
+    window: &mut Window,
+    cx: &gpui::App,
+) -> gpui::Pixels {
+    const MIN: f32 = 46.;
+    const MAX: f32 = 108.;
+    let font = gpui::Font {
+        family: cx.theme().font_family.clone(),
+        features: Default::default(),
+        fallbacks: None,
+        weight: Default::default(),
+        style: Default::default(),
+    };
+    let widest = rows
+        .iter()
+        .map(|(k, _)| {
+            window
+                .text_system()
+                .shape_line(
+                    gpui::SharedString::from(*k),
+                    px(12.),
+                    &[gpui::TextRun {
+                        len: k.len(),
+                        font: font.clone(),
+                        color: gpui::Hsla::default(),
+                        background_color: None,
+                        underline: None,
+                        strikethrough: None,
+                    }],
+                    None,
+                )
+                .width
+                .as_f32()
+        })
+        .fold(MIN, f32::max);
+    px(widest.clamp(MIN, MAX).ceil())
+}
+
 impl Tty7App {
     pub(crate) fn right_panel_open(&self, _cx: &gpui::App) -> bool {
         self.right_panel_visible && !self.tabs.is_empty()
@@ -426,6 +474,7 @@ impl Tty7App {
         self.sync_procs(pane_id, route, cx);
 
         let mono = cx.theme().mono_font_family.clone();
+        let label_w = info_label_column(&rows, window, cx);
         let mut list = v_flex().px(px(CONTENT_INSET)).py(px(2.)).gap(px(3.));
         for (k, v) in rows {
             list = list.child(
@@ -437,7 +486,8 @@ impl Tty7App {
                     .child(
                         div()
                             .flex_none()
-                            .w(px(46.))
+                            .w(label_w)
+                            .whitespace_nowrap()
                             .text_color(cx.theme().muted_foreground)
                             .child(k),
                     )