editor: Add configurable git gutter width setting (#61304)

## Summary

Adds a `gutter.git_gutter_width` setting that lets users pin the width,
in pixels, of the git diff hunk indicators in the editor gutter.

Previously the width was always derived from the buffer font size
(`floor(0.275 * line_height)`), which can render too thin or too thick
depending on font family and display pixel density. This adds an
optional override:

```json
{
  "gutter": {
    "git_gutter_width": 6
  }
}
```

When the setting is unset (`null`, the default), the width continues to
scale with the buffer font size, so existing behavior is unchanged.

## Motivation

Requested in [discussion
#27799](https://github.com/zed-industries/zed/discussions/27799). Beyond
the width itself, participants noted the git hunk hit target is
extremely narrow and hard to click. Because the hunk hitbox reuses the
painted strip bounds, setting a wider `git_gutter_width` also widens the
clickable area, addressing that complaint with the same setting.

## Changes

- `settings_content`: new `git_gutter_width: Option<f32>` on
`GutterContent`.
- `editor`: mirror field on the resolved `Gutter`; `gutter_strip_width`
now consults the setting, and the value flows through `diff_hunk_bounds`
(including the deleted-hunk marker) and the gutter layout anchors for
line numbers, folds, and expand toggles.
- `settings` (VS Code import): pass through the new field.
- Docs + `default.json`: document the new setting.

## Notes

- `Eq` was dropped from `GutterContent`/`Gutter` because `f32` is not
`Eq`; this matches the existing `EditorSettingsContent` convention for
float-bearing settings.

Release Notes:

- Added a `gutter.git_gutter_width` setting to configure the width of
git diff indicators in the editor gutter

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

assets/settings/default.json

@@ -695,6 +695,9 @@
     "folds": true,
     // Minimum number of characters to reserve space for in the gutter.
     "min_line_number_digits": 4,
+    // The width, in pixels, of the git diff hunk indicators in the gutter.
+    // When set to null, the width scales with the buffer font size.
+    "git_gutter_width": null,
   },
   "indent_guides": {
     // Whether to show indent guides in the editor.

crates/editor/src/editor_settings.rs

@@ -141,7 +141,7 @@ impl Minimap {
     }
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[derive(Copy, Clone, Debug, PartialEq)]
 pub struct Gutter {
     pub min_line_number_digits: usize,
     pub line_numbers: bool,
@@ -149,6 +149,7 @@ pub struct Gutter {
     pub breakpoints: bool,
     pub bookmarks: bool,
     pub folds: bool,
+    pub git_gutter_width: Option<f32>,
 }
 
 /// Forcefully enable or disable the scrollbar for each axis
@@ -267,6 +268,7 @@ impl Settings for EditorSettings {
                 bookmarks: gutter.bookmarks.unwrap(),
                 breakpoints: gutter.breakpoints.unwrap(),
                 folds: gutter.folds.unwrap(),
+                git_gutter_width: gutter.git_gutter_width,
             },
             scroll_beyond_last_line: editor.scroll_beyond_last_line.unwrap(),
             vertical_scroll_margin: editor.vertical_scroll_margin.unwrap() as f64,

crates/editor/src/element.rs

@@ -1676,6 +1676,7 @@ impl EditorElement {
                         gutter_hitbox.bounds,
                         hunk,
                         snapshot,
+                        cx,
                     );
                     *hitbox = Some(window.insert_hitbox(hunk_bounds, HitboxBehavior::BlockMouse));
                 }
@@ -2669,7 +2670,7 @@ impl EditorElement {
             .ilog10()
             + 1;
 
-        let git_gutter_width = Self::gutter_strip_width(line_height)
+        let git_gutter_width = Self::gutter_strip_width(line_height, cx)
             + gutter_dimensions
                 .git_blame_entries_width
                 .unwrap_or_default();
@@ -5228,6 +5229,7 @@ impl EditorElement {
                             layout.gutter_hitbox.bounds,
                             hunk,
                             &layout.position_map.snapshot,
+                            cx,
                         );
                         Some((
                             hunk_bounds,
@@ -5313,8 +5315,11 @@ impl EditorElement {
         });
     }
 
-    fn gutter_strip_width(line_height: Pixels) -> Pixels {
-        (0.275 * line_height).floor()
+    fn gutter_strip_width(line_height: Pixels, cx: &App) -> Pixels {
+        match EditorSettings::get_global(cx).gutter.git_gutter_width {
+            Some(width) => px(width),
+            None => (0.275 * line_height).floor(),
+        }
     }
 
     fn diff_hunk_bounds(
@@ -5323,9 +5328,10 @@ impl EditorElement {
         gutter_bounds: Bounds<Pixels>,
         hunk: &DisplayDiffHunk,
         snapshot: &EditorSnapshot,
+        cx: &App,
     ) -> Bounds<Pixels> {
         let scroll_top = scroll_position.y * ScrollPixelOffset::from(line_height);
-        let gutter_strip_width = Self::gutter_strip_width(line_height);
+        let gutter_strip_width = Self::gutter_strip_width(line_height, cx);
 
         match hunk {
             DisplayDiffHunk::Folded { display_row, .. } => {
@@ -5351,7 +5357,10 @@ impl EditorElement {
                             .into();
                     let end_y = start_y + line_height;
 
-                    let width = (0.35 * line_height).floor();
+                    let width = match EditorSettings::get_global(cx).gutter.git_gutter_width {
+                        Some(width) => px(width),
+                        None => (0.35 * line_height).floor(),
+                    };
                     let highlight_origin = gutter_bounds.origin + point(px(0.), start_y);
                     let highlight_size = size(width, end_y - start_y);
                     Bounds::new(highlight_origin, highlight_size)
@@ -6720,7 +6729,7 @@ impl Gutter<'_> {
             AvailableSpace::Definite(self.line_height),
         );
         let indicator_size = button.layout_as_root(available_space, window, cx);
-        let git_gutter_width = EditorElement::gutter_strip_width(self.line_height)
+        let git_gutter_width = EditorElement::gutter_strip_width(self.line_height, cx)
             + self.dimensions.git_blame_entries_width.unwrap_or_default();
 
         let x = git_gutter_width + px(2.);
@@ -9148,7 +9157,7 @@ impl Element for EditorElement {
                         );
                     }
 
-                    let git_gutter_width = Self::gutter_strip_width(line_height)
+                    let git_gutter_width = Self::gutter_strip_width(line_height, cx)
                         + gutter_dimensions
                             .git_blame_entries_width
                             .unwrap_or_default();

crates/settings/src/vscode_import.rs

@@ -350,6 +350,7 @@ impl VsCodeSettings {
                 "never" => Some(false),
                 _ => None,
             }),
+            git_gutter_width: None,
         })
     }
 

crates/settings_content/src/editor.rs

@@ -483,7 +483,7 @@ pub struct ScrollbarAxesContent {
 
 /// Gutter related settings
 #[with_fallible_options]
-#[derive(Clone, Debug, Default, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq, Eq)]
+#[derive(Clone, Debug, Default, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq)]
 pub struct GutterContent {
     /// Whether to show line numbers in the gutter.
     ///
@@ -509,6 +509,11 @@ pub struct GutterContent {
     ///
     /// Default: true
     pub folds: Option<bool>,
+    /// The width, in pixels, of the git diff hunk indicators in the gutter.
+    /// When unset, the width scales with the buffer font size.
+    ///
+    /// Default: null
+    pub git_gutter_width: Option<f32>,
 }
 
 /// Whether to display code lenses from language servers above code elements.

crates/settings_ui/src/page_data.rs

@@ -2182,7 +2182,7 @@ fn editor_page() -> SettingsPage {
         ]
     }
 
-    fn gutter_section() -> [SettingsPageItem; 9] {
+    fn gutter_section() -> [SettingsPageItem; 10] {
         [
             SettingsPageItem::SectionHeader("Gutter"),
             SettingsPageItem::SettingItem(SettingItem {
@@ -2339,6 +2339,30 @@ fn editor_page() -> SettingsPage {
                 metadata: None,
                 files: USER,
             }),
+            SettingsPageItem::SettingItem(SettingItem {
+                title: "Git Gutter Width",
+                description: "Width, in pixels, of the git diff indicators in the gutter. When unset, the width scales with the buffer font size.",
+                field: Box::new(SettingField {
+                    organization_override: None,
+                    json_path: Some("gutter.git_gutter_width"),
+                    pick: |settings_content| {
+                        settings_content
+                            .editor
+                            .gutter
+                            .as_ref()
+                            .and_then(|gutter| gutter.git_gutter_width.as_ref())
+                    },
+                    write: |settings_content, value, _| {
+                        settings_content
+                            .editor
+                            .gutter
+                            .get_or_insert_default()
+                            .git_gutter_width = value;
+                    },
+                }),
+                metadata: None,
+                files: USER,
+            }),
             SettingsPageItem::SettingItem(SettingItem {
                 title: "Inline Code Actions",
                 description: "Show code action button at start of buffer line.",

docs/src/reference/all-settings.md

@@ -838,7 +838,8 @@ List of `string` values
     "runnables": true,
     "breakpoints": true,
     "folds": true,
-    "min_line_number_digits": 4
+    "min_line_number_digits": 4,
+    "git_gutter_width": null
   }
 }
 ```
@@ -850,6 +851,7 @@ List of `string` values
 - `breakpoints`: Whether to show breakpoints in the gutter
 - `folds`: Whether to show fold buttons in the gutter
 - `min_line_number_digits`: Minimum number of characters to reserve space for in the gutter
+- `git_gutter_width`: The width, in pixels, of the git diff hunk indicators in the gutter. When `null`, the width scales with the buffer font size
 
 ## Hide Mouse