diff --git a/packages/ui/src/components/file-viewer/monaco-diff-viewer.tsx b/packages/ui/src/components/file-viewer/monaco-diff-viewer.tsx
index 6856fb24..26b7e6c0 100644
--- a/packages/ui/src/components/file-viewer/monaco-diff-viewer.tsx
+++ b/packages/ui/src/components/file-viewer/monaco-diff-viewer.tsx
@@ -15,6 +15,79 @@ interface MonacoDiffViewerProps {
   viewMode?: "split" | "unified"
   contextMode?: "expanded" | "collapsed"
   wordWrap?: "on" | "off"
+  unifiedGutterStyle?: "compact" | "classic"
+}
+
+function getLineCount(value: string): number {
+  if (!value) return 1
+  return value.split("\n").length
+}
+
+function getDigitCount(value: number): number {
+  return String(Math.max(1, value)).length
+}
+
+function getUnifiedGutterSizing(options: {
+  unifiedGutterStyle: "compact" | "classic" | null
+  before: string
+  after: string
+}) {
+  const beforeLineCount = getLineCount(options.before)
+  const afterLineCount = getLineCount(options.after)
+  const beforeDigitCount = getDigitCount(beforeLineCount)
+  const afterDigitCount = getDigitCount(afterLineCount)
+  const maxDigitCount = Math.max(beforeDigitCount, afterDigitCount)
+  const extraDigits = Math.max(0, maxDigitCount - 2)
+  // Reserve one extra character so the number lane keeps a visible gap before
+  // the +/- indicator lane once the line numbers grow beyond trivial widths.
+  const beforeNumberChars = Math.max(2, beforeDigitCount + 1)
+  const afterNumberChars = Math.max(2, afterDigitCount + 1)
+  const fourDigitPenalty = Math.max(0, maxDigitCount - 3)
+
+  if (options.unifiedGutterStyle === "compact") {
+    const sharedNumberChars = Math.max(beforeNumberChars, afterNumberChars)
+    return {
+      diffEditorLineNumbersMinChars: sharedNumberChars,
+      originalLineNumbersMinChars: sharedNumberChars,
+      modifiedLineNumbersMinChars: sharedNumberChars,
+      lineDecorationsWidth: 8 + extraDigits * 4 + fourDigitPenalty * 2,
+    }
+  }
+
+  if (options.unifiedGutterStyle === "classic") {
+    return {
+      diffEditorLineNumbersMinChars: Math.max(beforeNumberChars, afterNumberChars),
+      originalLineNumbersMinChars: beforeNumberChars,
+      modifiedLineNumbersMinChars: afterNumberChars,
+      lineDecorationsWidth: 10 + extraDigits * 4 + fourDigitPenalty * 4,
+    }
+  }
+
+  return {
+    diffEditorLineNumbersMinChars: 4,
+    originalLineNumbersMinChars: 4,
+    modifiedLineNumbersMinChars: 4,
+    lineDecorationsWidth: 12,
+  }
+}
+
+function getSplitGutterSizing(options: { before: string; after: string }) {
+  const beforeLineCount = getLineCount(options.before)
+  const afterLineCount = getLineCount(options.after)
+  const beforeDigitCount = getDigitCount(beforeLineCount)
+  const afterDigitCount = getDigitCount(afterLineCount)
+  const maxDigitCount = Math.max(beforeDigitCount, afterDigitCount)
+  const extraDigits = Math.max(0, maxDigitCount - 2)
+  const beforeNumberChars = Math.max(2, beforeDigitCount + 1)
+  const afterNumberChars = Math.max(2, afterDigitCount + 1)
+  const fourDigitPenalty = Math.max(0, maxDigitCount - 3)
+
+  return {
+    diffEditorLineNumbersMinChars: Math.max(beforeNumberChars, afterNumberChars),
+    originalLineNumbersMinChars: beforeNumberChars,
+    modifiedLineNumbersMinChars: afterNumberChars,
+    lineDecorationsWidth: 10 + extraDigits * 2 + fourDigitPenalty * 2,
+  }
 }
 
 export function MonacoDiffViewer(props: MonacoDiffViewerProps) {
@@ -95,30 +168,68 @@ export function MonacoDiffViewer(props: MonacoDiffViewerProps) {
     monaco.editor.setTheme(isDark() ? "vs-dark" : "vs")
   })
 
+  createEffect(() => {
+    if (!host) return
+    host.dataset.viewMode = props.viewMode === "split" ? "split" : "unified"
+    host.dataset.unifiedGutterStyle = props.unifiedGutterStyle ?? ""
+  })
+
   createEffect(() => {
     if (!ready() || !monaco || !diffEditor) return
     const viewMode = props.viewMode === "unified" ? "unified" : "split"
     const contextMode = props.contextMode === "collapsed" ? "collapsed" : "expanded"
     const wordWrap = props.wordWrap === "on" ? "on" : "off"
+    const unifiedGutterStyle = viewMode === "unified" ? props.unifiedGutterStyle ?? null : null
+    const { before, after } = resolvedContent()
+    const sizing =
+      viewMode === "unified"
+        ? getUnifiedGutterSizing({
+            unifiedGutterStyle,
+            before,
+            after,
+          })
+        : getSplitGutterSizing({ before, after })
+    const {
+      diffEditorLineNumbersMinChars,
+      originalLineNumbersMinChars,
+      modifiedLineNumbersMinChars,
+      lineDecorationsWidth,
+    } = sizing
+    const compactUnifiedGutter = unifiedGutterStyle === "compact"
 
     diffEditor.updateOptions({
       renderSideBySide: viewMode === "split",
       renderSideBySideInlineBreakpoint: 0,
+      compactMode: compactUnifiedGutter,
+      renderIndicators: true,
+      lineNumbersMinChars: diffEditorLineNumbersMinChars,
+      lineDecorationsWidth,
       hideUnchangedRegions:
         contextMode === "collapsed"
           ? { enabled: true }
           : { enabled: false },
       wordWrap,
+      experimental: {
+        useTrueInlineView: compactUnifiedGutter,
+      },
     })
 
     try {
-      diffEditor.getOriginalEditor?.()?.updateOptions?.({ wordWrap })
+      diffEditor.getOriginalEditor?.()?.updateOptions?.({
+        wordWrap,
+        lineNumbersMinChars: originalLineNumbersMinChars,
+        lineDecorationsWidth,
+      })
     } catch {
       // ignore
     }
 
     try {
-      diffEditor.getModifiedEditor?.()?.updateOptions?.({ wordWrap })
+      diffEditor.getModifiedEditor?.()?.updateOptions?.({
+        wordWrap,
+        lineNumbersMinChars: modifiedLineNumbersMinChars,
+        lineDecorationsWidth,
+      })
     } catch {
       // ignore
     }
diff --git a/packages/ui/src/components/instance/shell/right-panel/RightPanel.tsx b/packages/ui/src/components/instance/shell/right-panel/RightPanel.tsx
index c031ac87..91aae989 100644
--- a/packages/ui/src/components/instance/shell/right-panel/RightPanel.tsx
+++ b/packages/ui/src/components/instance/shell/right-panel/RightPanel.tsx
@@ -21,6 +21,7 @@ import type { BackgroundProcess } from "../../../../../../server/src/api-types"
 import type { Session } from "../../../../types/session"
 import type { DrawerViewState } from "../types"
 import type { DiffContextMode, DiffViewMode, DiffWordWrapMode, RightPanelTab } from "./types"
+import { preferences, setGitDiffUnifiedGutterStyle } from "../../../../stores/preferences"
 
 import { getDefaultWorktreeSlug, getOrCreateWorktreeClient, getWorktreeSlugForSession } from "../../../../stores/worktrees"
 import { requestData } from "../../../../lib/opencode-api"
@@ -921,9 +922,11 @@ const RightPanel: Component<RightPanelProps> = (props) => {
               diffViewMode={diffViewMode}
               diffContextMode={diffContextMode}
               diffWordWrapMode={diffWordWrapMode}
+              unifiedGutterStyle={() => preferences().gitDiffUnifiedGutterStyle}
               onViewModeChange={setDiffViewMode}
               onContextModeChange={setDiffContextMode}
               onWordWrapModeChange={setDiffWordWrapMode}
+              onUnifiedGutterStyleChange={setGitDiffUnifiedGutterStyle}
               onOpenFile={(path: string) => void openGitFile(path)}
               onRefresh={() => void refreshGitStatus()}
               listOpen={gitChangesListOpen}
diff --git a/packages/ui/src/components/instance/shell/right-panel/tabs/GitChangesTab.tsx b/packages/ui/src/components/instance/shell/right-panel/tabs/GitChangesTab.tsx
index 019dce1d..c03d8b76 100644
--- a/packages/ui/src/components/instance/shell/right-panel/tabs/GitChangesTab.tsx
+++ b/packages/ui/src/components/instance/shell/right-panel/tabs/GitChangesTab.tsx
@@ -6,6 +6,7 @@ import { RefreshCw } from "lucide-solid"
 import DiffToolbar from "../components/DiffToolbar"
 import SplitFilePanel from "../components/SplitFilePanel"
 import type { DiffContextMode, DiffViewMode, DiffWordWrapMode } from "../types"
+import type { GitDiffUnifiedGutterStyle } from "../../../../../stores/preferences"
 
 const LazyMonacoDiffViewer = lazy(() =>
   import("../../../../file-viewer/monaco-diff-viewer").then((module) => ({ default: module.MonacoDiffViewer })),
@@ -32,9 +33,11 @@ interface GitChangesTabProps {
   diffViewMode: Accessor<DiffViewMode>
   diffContextMode: Accessor<DiffContextMode>
   diffWordWrapMode: Accessor<DiffWordWrapMode>
+  unifiedGutterStyle: Accessor<GitDiffUnifiedGutterStyle>
   onViewModeChange: (mode: DiffViewMode) => void
   onContextModeChange: (mode: DiffContextMode) => void
   onWordWrapModeChange: (mode: DiffWordWrapMode) => void
+  onUnifiedGutterStyleChange: (style: GitDiffUnifiedGutterStyle) => void
 
   onOpenFile: (path: string) => void
   onRefresh: () => void
@@ -139,6 +142,7 @@ const GitChangesTab: Component<GitChangesTabProps> = (props) => {
                           viewMode={props.diffViewMode()}
                           contextMode={props.diffContextMode()}
                           wordWrap={props.diffWordWrapMode()}
+                          unifiedGutterStyle={props.unifiedGutterStyle()}
                         />
                       </Suspense>
                     )}
@@ -264,6 +268,7 @@ const GitChangesTab: Component<GitChangesTabProps> = (props) => {
                 onContextModeChange={props.onContextModeChange}
                 onWordWrapModeChange={props.onWordWrapModeChange}
               />
+
             </>
           }
         list={{ panel: renderListPanel, overlay: renderListOverlay }}
diff --git a/packages/ui/src/components/settings/appearance-settings-section.tsx b/packages/ui/src/components/settings/appearance-settings-section.tsx
index 10974d0b..4a3495ab 100644
--- a/packages/ui/src/components/settings/appearance-settings-section.tsx
+++ b/packages/ui/src/components/settings/appearance-settings-section.tsx
@@ -5,6 +5,7 @@ import { useI18n } from "../../lib/i18n"
 import { useTheme, type ThemeMode } from "../../lib/theme"
 import { useConfig } from "../../stores/preferences"
 import { getBehaviorSettings, type BehaviorSetting } from "../../lib/settings/behavior-registry"
+import type { GitDiffUnifiedGutterStyle } from "../../stores/preferences"
 
 const themeModeOptions: Array<{ value: ThemeMode; icon: typeof Laptop }> = [
   { value: "system", icon: Laptop },
@@ -26,12 +27,21 @@ export const AppearanceSettingsSection: Component = () => {
     togglePromptSubmitOnEnter,
     toggleShowPromptVoiceInput,
     setDiffViewMode,
+    setGitDiffUnifiedGutterStyle,
     setToolOutputExpansion,
     setDiagnosticsExpansion,
     setThinkingBlocksExpansion,
     setToolInputsVisibility,
   } = useConfig()
 
+  const gitDiffGutterStyleOptions = createMemo<Array<{ value: GitDiffUnifiedGutterStyle; label: string }>>(() => [
+    { value: "compact", label: t("settings.appearance.gitDiff.gutterMode.option.compact") },
+    { value: "classic", label: t("settings.appearance.gitDiff.gutterMode.option.normal") },
+  ])
+  const selectedGitDiffGutterStyle = createMemo(() =>
+    gitDiffGutterStyleOptions().find((option) => option.value === preferences().gitDiffUnifiedGutterStyle),
+  )
+
   const behaviorSettings = createMemo(() =>
     getBehaviorSettings({
       preferences,
@@ -265,6 +275,49 @@ export const AppearanceSettingsSection: Component = () => {
 
         <div class="settings-stack">
           <For each={behaviorSettings()}>{(setting) => <BehaviorRow setting={setting} />}</For>
+
+          <div class="settings-toggle-row">
+            <div>
+              <div class="settings-toggle-title">{t("settings.appearance.gitDiff.gutterMode.title")}</div>
+              <div class="settings-toggle-caption">{t("settings.appearance.gitDiff.gutterMode.subtitle")}</div>
+            </div>
+            <Select<{ value: GitDiffUnifiedGutterStyle; label: string }>
+              value={selectedGitDiffGutterStyle()}
+              onChange={(opt) => {
+                if (!opt) return
+                setGitDiffUnifiedGutterStyle(opt.value)
+              }}
+              options={gitDiffGutterStyleOptions()}
+              optionValue="value"
+              optionTextValue="label"
+              itemComponent={(itemProps) => (
+                <Select.Item item={itemProps.item} class="selector-option">
+                  <Select.ItemLabel class="selector-option-label">{itemProps.item.rawValue.label}</Select.ItemLabel>
+                </Select.Item>
+              )}
+            >
+              <Select.Trigger class="selector-trigger" aria-label={t("settings.appearance.gitDiff.gutterMode.title")}>
+                <div class="flex-1 min-w-0">
+                  <Select.Value<{ value: GitDiffUnifiedGutterStyle; label: string }>>
+                    {(state) => (
+                      <span class="selector-trigger-primary selector-trigger-primary--align-left">
+                        {state.selectedOption()?.label}
+                      </span>
+                    )}
+                  </Select.Value>
+                </div>
+                <Select.Icon class="selector-trigger-icon">
+                  <ChevronDown class="w-3 h-3" />
+                </Select.Icon>
+              </Select.Trigger>
+
+              <Select.Portal>
+                <Select.Content class="selector-popover">
+                  <Select.Listbox class="selector-listbox" />
+                </Select.Content>
+              </Select.Portal>
+            </Select>
+          </div>
         </div>
       </div>
     </div>
diff --git a/packages/ui/src/lib/i18n/messages/en/instance.ts b/packages/ui/src/lib/i18n/messages/en/instance.ts
index d56f481c..9258aa9c 100644
--- a/packages/ui/src/lib/i18n/messages/en/instance.ts
+++ b/packages/ui/src/lib/i18n/messages/en/instance.ts
@@ -146,6 +146,10 @@ export const instanceMessages = {
   "instanceShell.diff.switchToUnified": "Switch to unified view",
   "instanceShell.diff.enableWordWrap": "Enable word wrap",
   "instanceShell.diff.disableWordWrap": "Disable word wrap",
+  "instanceShell.diff.switchToCompactGutter": "Switch unified gutter to compact",
+  "instanceShell.diff.switchToClassicGutter": "Switch unified gutter to classic",
+  "instanceShell.diff.gutterStyleCompact": "Compact",
+  "instanceShell.diff.gutterStyleClassic": "Classic",
   "instanceShell.worktree.create": "+ Create worktree",
 
   "instanceShell.plan.noSessionSelected": "Select a session to view plan.",
diff --git a/packages/ui/src/lib/i18n/messages/en/settings.ts b/packages/ui/src/lib/i18n/messages/en/settings.ts
index f77b7b48..10b9943c 100644
--- a/packages/ui/src/lib/i18n/messages/en/settings.ts
+++ b/packages/ui/src/lib/i18n/messages/en/settings.ts
@@ -137,6 +137,10 @@ export const settingsMessages = {
   "settings.behavior.diffView.subtitle": "Choose how tool-call diffs are displayed.",
   "settings.behavior.diffView.option.split": "Split",
   "settings.behavior.diffView.option.unified": "Unified",
+  "settings.appearance.gitDiff.gutterMode.title": "Git diff gutter mode",
+  "settings.appearance.gitDiff.gutterMode.subtitle": "Choose the Monaco gutter presentation used for Git Changes diffs.",
+  "settings.appearance.gitDiff.gutterMode.option.compact": "Compact",
+  "settings.appearance.gitDiff.gutterMode.option.normal": "Normal",
   "settings.behavior.toolOutputsDefault.title": "Tool outputs default",
   "settings.behavior.toolOutputsDefault.subtitle": "Choose whether tool outputs start expanded or collapsed.",
   "settings.behavior.diagnosticsDefault.title": "Diagnostics default",
diff --git a/packages/ui/src/lib/i18n/messages/es/instance.ts b/packages/ui/src/lib/i18n/messages/es/instance.ts
index e0293f1f..56ad2360 100644
--- a/packages/ui/src/lib/i18n/messages/es/instance.ts
+++ b/packages/ui/src/lib/i18n/messages/es/instance.ts
@@ -130,6 +130,10 @@ export const instanceMessages = {
   "instanceShell.gitChanges.loading": "Cargando cambios de Git...",
   "instanceShell.gitChanges.empty": "Aún no hay cambios de Git.",
   "instanceShell.gitChanges.deleted": "Eliminado",
+  "instanceShell.diff.switchToCompactGutter": "Cambiar el gutter unificado a compacto",
+  "instanceShell.diff.switchToClassicGutter": "Cambiar el gutter unificado a clásico",
+  "instanceShell.diff.gutterStyleCompact": "Compacto",
+  "instanceShell.diff.gutterStyleClassic": "Clásico",
 
   "instanceShell.filesShell.fileListTitle": "Lista de archivos",
   "instanceShell.filesShell.mobileSelectorLabel": "Seleccionar archivo",
diff --git a/packages/ui/src/lib/i18n/messages/fr/instance.ts b/packages/ui/src/lib/i18n/messages/fr/instance.ts
index 26c56844..547c2bd8 100644
--- a/packages/ui/src/lib/i18n/messages/fr/instance.ts
+++ b/packages/ui/src/lib/i18n/messages/fr/instance.ts
@@ -130,6 +130,10 @@ export const instanceMessages = {
   "instanceShell.gitChanges.loading": "Chargement des changements Git...",
   "instanceShell.gitChanges.empty": "Aucun changement Git pour l'instant.",
   "instanceShell.gitChanges.deleted": "Supprimé",
+  "instanceShell.diff.switchToCompactGutter": "Passer la gouttière unifiée en mode compact",
+  "instanceShell.diff.switchToClassicGutter": "Passer la gouttière unifiée en mode classique",
+  "instanceShell.diff.gutterStyleCompact": "Compact",
+  "instanceShell.diff.gutterStyleClassic": "Classique",
 
   "instanceShell.filesShell.fileListTitle": "Liste des fichiers",
   "instanceShell.filesShell.mobileSelectorLabel": "Sélectionner un fichier",
diff --git a/packages/ui/src/lib/i18n/messages/he/instance.ts b/packages/ui/src/lib/i18n/messages/he/instance.ts
index 1db1b29c..f78f223b 100644
--- a/packages/ui/src/lib/i18n/messages/he/instance.ts
+++ b/packages/ui/src/lib/i18n/messages/he/instance.ts
@@ -144,6 +144,10 @@ export const instanceMessages = {
   "instanceShell.diff.switchToUnified": "עבור לתצוגה מאוחדת",
   "instanceShell.diff.enableWordWrap": "הפעל גלישת מילים",
   "instanceShell.diff.disableWordWrap": "כבה גלישת מילים",
+  "instanceShell.diff.switchToCompactGutter": "עבור לשוליים מאוחדים קומפקטיים",
+  "instanceShell.diff.switchToClassicGutter": "עבור לשוליים מאוחדים קלאסיים",
+  "instanceShell.diff.gutterStyleCompact": "קומפקטי",
+  "instanceShell.diff.gutterStyleClassic": "קלאסי",
   "instanceShell.worktree.create": "+ צור worktree",
 
   "instanceShell.plan.noSessionSelected": "בחר סשן לצפייה בתוכנית.",
diff --git a/packages/ui/src/lib/i18n/messages/ja/instance.ts b/packages/ui/src/lib/i18n/messages/ja/instance.ts
index 546a22ef..ae4afab3 100644
--- a/packages/ui/src/lib/i18n/messages/ja/instance.ts
+++ b/packages/ui/src/lib/i18n/messages/ja/instance.ts
@@ -130,6 +130,10 @@ export const instanceMessages = {
   "instanceShell.gitChanges.loading": "Git の変更を読み込み中...",
   "instanceShell.gitChanges.empty": "Git の変更はまだありません。",
   "instanceShell.gitChanges.deleted": "削除済み",
+  "instanceShell.diff.switchToCompactGutter": "統合ガターをコンパクト表示に切り替え",
+  "instanceShell.diff.switchToClassicGutter": "統合ガターをクラシック表示に切り替え",
+  "instanceShell.diff.gutterStyleCompact": "コンパクト",
+  "instanceShell.diff.gutterStyleClassic": "クラシック",
 
   "instanceShell.filesShell.fileListTitle": "ファイル一覧",
   "instanceShell.filesShell.mobileSelectorLabel": "ファイルを選択",
diff --git a/packages/ui/src/lib/i18n/messages/ru/instance.ts b/packages/ui/src/lib/i18n/messages/ru/instance.ts
index 8a4b6a89..1ceb2505 100644
--- a/packages/ui/src/lib/i18n/messages/ru/instance.ts
+++ b/packages/ui/src/lib/i18n/messages/ru/instance.ts
@@ -130,6 +130,10 @@ export const instanceMessages = {
   "instanceShell.gitChanges.loading": "Загрузка изменений Git...",
   "instanceShell.gitChanges.empty": "Изменений Git пока нет.",
   "instanceShell.gitChanges.deleted": "Удалено",
+  "instanceShell.diff.switchToCompactGutter": "Переключить объединённую область на компактный режим",
+  "instanceShell.diff.switchToClassicGutter": "Переключить объединённую область на классический режим",
+  "instanceShell.diff.gutterStyleCompact": "Компактный",
+  "instanceShell.diff.gutterStyleClassic": "Классический",
 
   "instanceShell.filesShell.fileListTitle": "Список файлов",
   "instanceShell.filesShell.mobileSelectorLabel": "Выбрать файл",
diff --git a/packages/ui/src/lib/i18n/messages/zh-Hans/instance.ts b/packages/ui/src/lib/i18n/messages/zh-Hans/instance.ts
index 10675d0a..0c62bad8 100644
--- a/packages/ui/src/lib/i18n/messages/zh-Hans/instance.ts
+++ b/packages/ui/src/lib/i18n/messages/zh-Hans/instance.ts
@@ -130,6 +130,10 @@ export const instanceMessages = {
   "instanceShell.gitChanges.loading": "正在加载 Git 更改...",
   "instanceShell.gitChanges.empty": "暂无 Git 更改。",
   "instanceShell.gitChanges.deleted": "已删除",
+  "instanceShell.diff.switchToCompactGutter": "切换统一边栏为紧凑模式",
+  "instanceShell.diff.switchToClassicGutter": "切换统一边栏为经典模式",
+  "instanceShell.diff.gutterStyleCompact": "紧凑",
+  "instanceShell.diff.gutterStyleClassic": "经典",
 
   "instanceShell.filesShell.fileListTitle": "文件列表",
   "instanceShell.filesShell.mobileSelectorLabel": "选择文件",
diff --git a/packages/ui/src/stores/preferences.tsx b/packages/ui/src/stores/preferences.tsx
index 21209c75..f5b04813 100644
--- a/packages/ui/src/stores/preferences.tsx
+++ b/packages/ui/src/stores/preferences.tsx
@@ -26,6 +26,7 @@ export interface ModelPreference {
 }
 
 export type DiffViewMode = "split" | "unified"
+export type GitDiffUnifiedGutterStyle = "compact" | "classic"
 export type ExpansionPreference = "expanded" | "collapsed"
 export type ToolInputsVisibilityPreference = "hidden" | "collapsed" | "expanded"
 export type ListeningMode = "local" | "all"
@@ -59,6 +60,7 @@ export interface UiSettings {
   showPromptVoiceInput: boolean
   locale?: string
   diffViewMode: DiffViewMode
+  gitDiffUnifiedGutterStyle: GitDiffUnifiedGutterStyle
   toolOutputExpansion: ExpansionPreference
   diagnosticsExpansion: ExpansionPreference
   toolInputsVisibility: ToolInputsVisibilityPreference
@@ -136,6 +138,7 @@ const defaultUiSettings: UiSettings = {
   promptSubmitOnEnter: false,
   showPromptVoiceInput: true,
   diffViewMode: "split",
+  gitDiffUnifiedGutterStyle: "compact",
   toolOutputExpansion: "expanded",
   diagnosticsExpansion: "expanded",
   toolInputsVisibility: "collapsed",
@@ -160,6 +163,8 @@ const defaultSpeechSettings: SpeechSettings = {
 
 function normalizeUiSettings(input?: Partial<UiSettings> | null): UiSettings {
   const sanitized = input ?? {}
+  const gitDiffUnifiedGutterStyle: GitDiffUnifiedGutterStyle =
+    sanitized.gitDiffUnifiedGutterStyle === "classic" ? "classic" : "compact"
   return {
     showThinkingBlocks: sanitized.showThinkingBlocks ?? defaultUiSettings.showThinkingBlocks,
     showKeyboardShortcutHints:
@@ -170,6 +175,7 @@ function normalizeUiSettings(input?: Partial<UiSettings> | null): UiSettings {
     showPromptVoiceInput: sanitized.showPromptVoiceInput ?? defaultUiSettings.showPromptVoiceInput,
     locale: sanitized.locale ?? defaultUiSettings.locale,
     diffViewMode: sanitized.diffViewMode ?? defaultUiSettings.diffViewMode,
+    gitDiffUnifiedGutterStyle,
     toolOutputExpansion: sanitized.toolOutputExpansion ?? defaultUiSettings.toolOutputExpansion,
     diagnosticsExpansion: sanitized.diagnosticsExpansion ?? defaultUiSettings.diagnosticsExpansion,
     toolInputsVisibility:
@@ -622,6 +628,11 @@ function setDiffViewMode(mode: DiffViewMode): void {
   updateUiSettings({ diffViewMode: mode })
 }
 
+function setGitDiffUnifiedGutterStyle(style: GitDiffUnifiedGutterStyle): void {
+  if (preferences().gitDiffUnifiedGutterStyle === style) return
+  updateUiSettings({ gitDiffUnifiedGutterStyle: style })
+}
+
 function setToolOutputExpansion(mode: ExpansionPreference): void {
   if (preferences().toolOutputExpansion === mode) return
   updateUiSettings({ toolOutputExpansion: mode })
@@ -742,6 +753,7 @@ interface ConfigContextValue {
   togglePromptSubmitOnEnter: typeof togglePromptSubmitOnEnter
   toggleShowPromptVoiceInput: typeof toggleShowPromptVoiceInput
   setDiffViewMode: typeof setDiffViewMode
+  setGitDiffUnifiedGutterStyle: typeof setGitDiffUnifiedGutterStyle
   setToolOutputExpansion: typeof setToolOutputExpansion
   setDiagnosticsExpansion: typeof setDiagnosticsExpansion
   setThinkingBlocksExpansion: typeof setThinkingBlocksExpansion
@@ -793,6 +805,7 @@ const configContextValue: ConfigContextValue = {
   togglePromptSubmitOnEnter,
   toggleShowPromptVoiceInput,
   setDiffViewMode,
+  setGitDiffUnifiedGutterStyle,
   setToolOutputExpansion,
   setDiagnosticsExpansion,
   setThinkingBlocksExpansion,
@@ -874,6 +887,7 @@ export {
   togglePromptSubmitOnEnter,
   toggleShowPromptVoiceInput,
   setDiffViewMode,
+  setGitDiffUnifiedGutterStyle,
   setToolOutputExpansion,
   setDiagnosticsExpansion,
   setThinkingBlocksExpansion,
diff --git a/packages/ui/src/styles/panels/right-panel.css b/packages/ui/src/styles/panels/right-panel.css
index 8af0cac3..0352ec04 100644
--- a/packages/ui/src/styles/panels/right-panel.css
+++ b/packages/ui/src/styles/panels/right-panel.css
@@ -337,6 +337,45 @@
   direction: ltr;
 }
 
+.file-viewer-content--monaco .monaco-viewer[data-unified-gutter-style="compact"] .line-numbers {
+  text-align: left !important;
+  padding-left: 4px;
+}
+
+.file-viewer-content--monaco .monaco-viewer[data-unified-gutter-style="classic"] .line-numbers {
+  text-align: left !important;
+  padding-left: 4px;
+}
+
+.file-viewer-content--monaco .monaco-viewer[data-view-mode="split"] .editor.original .line-numbers,
+.file-viewer-content--monaco .monaco-viewer[data-view-mode="split"] .editor.modified .line-numbers {
+  text-align: left !important;
+  padding-left: 4px;
+}
+
+.file-viewer-content--monaco .monaco-viewer[data-view-mode="split"] .editor.original .glyph-margin {
+  width: 0 !important;
+}
+
+.file-viewer-content--monaco .monaco-viewer[data-view-mode="split"] .editor.original .line-numbers {
+  left: 0 !important;
+}
+
+.file-viewer-content--monaco .monaco-viewer[data-view-mode="split"] .editor.original .cldr.delete-sign {
+  left: 14px !important;
+}
+
+.file-viewer-content--monaco .monaco-viewer[data-view-mode="split"] .editor.original .margin,
+.file-viewer-content--monaco .monaco-viewer[data-view-mode="split"] .editor.original .margin-view-zones,
+.file-viewer-content--monaco .monaco-viewer[data-view-mode="split"] .editor.original .margin-view-overlays {
+  width: 24px !important;
+}
+
+.file-viewer-content--monaco .monaco-viewer[data-view-mode="split"] .editor.original .editor-scrollable {
+  left: 24px !important;
+  width: calc(100% - 24px) !important;
+}
+
 .file-viewer-empty {
   @apply flex flex-col items-center justify-center h-full gap-3 text-center;
   color: var(--text-muted);