feat: add editor component

crates/theme/src/lib.rs

@@ -57,6 +57,8 @@ pub struct Theme {
     pub titlebar_height: Pixels,
     /// The platform's native root font size; rem-based sizing scales with it.
     pub root_font_size: Pixels,
+    /// The platform's monospace family, for code surfaces.
+    pub mono_font: &'static str,
     pub sizes: SizeTable,
     pub accessibility: AccessibilityPreferences,
 }
@@ -411,6 +413,7 @@ impl Theme {
             scrollbar: resolved.scrollbar,
             titlebar_height: resolved.titlebar_height,
             root_font_size: resolved.root_font_size,
+            mono_font: resolved.mono_font,
             sizes: resolved.sizes,
             accessibility: resolved.accessibility,
         }

crates/theme/src/resolve.rs

@@ -33,6 +33,8 @@ pub struct ResolvedTheme {
     pub titlebar_height: gpui::Pixels,
     /// The platform's native root font size; the fallback theme uses 16.
     pub root_font_size: gpui::Pixels,
+    /// The platform's monospace family, for code surfaces.
+    pub mono_font: &'static str,
     pub sizes: SizeTable,
     pub accessibility: crate::system::AccessibilityPreferences,
 }
@@ -244,11 +246,23 @@ pub(crate) fn resolve(
         },
         titlebar_height,
         root_font_size,
+        mono_font: mono_font(),
         sizes,
         accessibility,
     }
 }
 
+/// The platform's monospace family, for code surfaces.
+fn mono_font() -> &'static str {
+    if cfg!(target_os = "macos") {
+        "Menlo"
+    } else if cfg!(target_os = "windows") {
+        "Consolas"
+    } else {
+        "monospace"
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;