feat: Add option to hide line numbers in code blocks (#5857)

Co-authored-by: Jacob Richman <jacob314@gmail.com>

packages/cli/src/config/settings.ts

@@ -141,6 +141,7 @@ export interface Settings {
   loadMemoryFromIncludeDirectories?: boolean;
 
   chatCompression?: ChatCompressionSettings;
+  showLineNumbers?: boolean;
 }
 
 export interface SettingsError {

packages/cli/src/gemini.tsx

@@ -41,6 +41,7 @@ import { validateNonInteractiveAuth } from './validateNonInterActiveAuth.js';
 import { checkForUpdates } from './ui/utils/updateCheck.js';
 import { handleAutoUpdate } from './utils/handleAutoUpdate.js';
 import { appEvents, AppEvent } from './utils/events.js';
+import { SettingsContext } from './ui/contexts/SettingsContext.js';
 
 export function validateDnsResolutionOrder(
   order: string | undefined,
@@ -257,12 +258,14 @@ export async function main() {
     setWindowTitle(basename(workspaceRoot), settings);
     const instance = render(
       <React.StrictMode>
-        <AppWrapper
-          config={config}
-          settings={settings}
-          startupWarnings={startupWarnings}
-          version={version}
-        />
+        <SettingsContext.Provider value={settings}>
+          <AppWrapper
+            config={config}
+            settings={settings}
+            startupWarnings={startupWarnings}
+            version={version}
+          />
+        </SettingsContext.Provider>
       </React.StrictMode>,
       { exitOnCtrlC: false },
     );

packages/cli/src/ui/contexts/SettingsContext.tsx

@@ -0,0 +1,20 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import React, { useContext } from 'react';
+import { LoadedSettings } from '../../config/settings.js';
+
+export const SettingsContext = React.createContext<LoadedSettings | undefined>(
+  undefined,
+);
+
+export const useSettings = () => {
+  const context = useContext(SettingsContext);
+  if (context === undefined) {
+    throw new Error('useSettings must be used within a SettingsProvider');
+  }
+  return context;
+};

packages/cli/src/ui/utils/CodeColorizer.tsx

@@ -20,6 +20,7 @@ import {
   MaxSizedBox,
   MINIMUM_MAX_HEIGHT,
 } from '../components/shared/MaxSizedBox.js';
+import { LoadedSettings } from '../../config/settings.js';
 
 // Configure theming and parsing utilities.
 const lowlight = createLowlight(common);
@@ -129,9 +130,11 @@ export function colorizeCode(
   availableHeight?: number,
   maxWidth?: number,
   theme?: Theme,
+  settings?: LoadedSettings,
 ): React.ReactNode {
   const codeToHighlight = code.replace(/\n$/, '');
   const activeTheme = theme || themeManager.getActiveTheme();
+  const showLineNumbers = settings?.merged.showLineNumbers ?? true;
 
   try {
     // Render the HAST tree using the adapted theme
@@ -167,12 +170,14 @@ export function colorizeCode(
 
           return (
             <Box key={index}>
-              <Text color={activeTheme.colors.Gray}>
-                {`${String(index + 1 + hiddenLinesCount).padStart(
-                  padWidth,
-                  ' ',
-                )} `}
-              </Text>
+              {showLineNumbers && (
+                <Text color={activeTheme.colors.Gray}>
+                  {`${String(index + 1 + hiddenLinesCount).padStart(
+                    padWidth,
+                    ' ',
+                  )} `}
+                </Text>
+              )}
               <Text color={activeTheme.defaultColor} wrap="wrap">
                 {contentToRender}
               </Text>
@@ -198,9 +203,11 @@ export function colorizeCode(
       >
         {lines.map((line, index) => (
           <Box key={index}>
-            <Text color={activeTheme.defaultColor}>
-              {`${String(index + 1).padStart(padWidth, ' ')} `}
-            </Text>
+            {showLineNumbers && (
+              <Text color={activeTheme.defaultColor}>
+                {`${String(index + 1).padStart(padWidth, ' ')} `}
+              </Text>
+            )}
             <Text color={activeTheme.colors.Gray}>{line}</Text>
           </Box>
         ))}

packages/cli/src/ui/utils/MarkdownDisplay.test.tsx

@@ -7,6 +7,8 @@
 import { render } from 'ink-testing-library';
 import { describe, it, expect, vi, beforeEach } from 'vitest';
 import { MarkdownDisplay } from './MarkdownDisplay.js';
+import { LoadedSettings } from '../../config/settings.js';
+import { SettingsContext } from '../contexts/SettingsContext.js';
 
 describe('<MarkdownDisplay />', () => {
   const baseProps = {
@@ -15,19 +17,32 @@ describe('<MarkdownDisplay />', () => {
     availableTerminalHeight: 40,
   };
 
+  const mockSettings = new LoadedSettings(
+    { path: '', settings: {} },
+    { path: '', settings: {} },
+    { path: '', settings: {} },
+    [],
+  );
+
   beforeEach(() => {
     vi.clearAllMocks();
   });
 
   it('renders nothing for empty text', () => {
-    const { lastFrame } = render(<MarkdownDisplay {...baseProps} text="" />);
+    const { lastFrame } = render(
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text="" />
+      </SettingsContext.Provider>,
+    );
     expect(lastFrame()).toMatchSnapshot();
   });
 
   it('renders a simple paragraph', () => {
     const text = 'Hello, world.';
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -40,7 +55,9 @@ describe('<MarkdownDisplay />', () => {
 #### Header 4
 `;
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -48,7 +65,9 @@ describe('<MarkdownDisplay />', () => {
   it('renders a fenced code block with a language', () => {
     const text = '```javascript\nconst x = 1;\nconsole.log(x);\n```';
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -56,7 +75,9 @@ describe('<MarkdownDisplay />', () => {
   it('renders a fenced code block without a language', () => {
     const text = '```\nplain text\n```';
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -64,7 +85,9 @@ describe('<MarkdownDisplay />', () => {
   it('handles unclosed (pending) code blocks', () => {
     const text = '```typescript\nlet y = 2;';
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} isPending={true} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} isPending={true} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -76,7 +99,9 @@ describe('<MarkdownDisplay />', () => {
 + item C
 `;
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -88,7 +113,9 @@ describe('<MarkdownDisplay />', () => {
     * Level 3
 `;
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -99,7 +126,9 @@ describe('<MarkdownDisplay />', () => {
 2. Second item
 `;
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -113,7 +142,9 @@ World
 Test
 `;
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -126,7 +157,9 @@ Test
 | Cell 3   | Cell 4   |
 `;
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -138,7 +171,9 @@ Some text before.
 |---|
 | 1 | 2 |`;
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -148,7 +183,9 @@ Some text before.
 
 Paragraph 2.`;
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
@@ -169,8 +206,39 @@ some code
 Another paragraph.
 `;
     const { lastFrame } = render(
-      <MarkdownDisplay {...baseProps} text={text} />,
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
     );
     expect(lastFrame()).toMatchSnapshot();
   });
+
+  it('hides line numbers in code blocks when showLineNumbers is false', () => {
+    const text = '```javascript\nconst x = 1;\n```';
+    const settings = new LoadedSettings(
+      { path: '', settings: {} },
+      { path: '', settings: { showLineNumbers: false } },
+      { path: '', settings: {} },
+      [],
+    );
+
+    const { lastFrame } = render(
+      <SettingsContext.Provider value={settings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
+    );
+    expect(lastFrame()).toMatchSnapshot();
+    expect(lastFrame()).not.toContain(' 1 ');
+  });
+
+  it('shows line numbers in code blocks by default', () => {
+    const text = '```javascript\nconst x = 1;\n```';
+    const { lastFrame } = render(
+      <SettingsContext.Provider value={mockSettings}>
+        <MarkdownDisplay {...baseProps} text={text} />
+      </SettingsContext.Provider>,
+    );
+    expect(lastFrame()).toMatchSnapshot();
+    expect(lastFrame()).toContain(' 1 ');
+  });
 });

packages/cli/src/ui/utils/MarkdownDisplay.tsx

@@ -10,6 +10,7 @@ import { Colors } from '../colors.js';
 import { colorizeCode } from './CodeColorizer.js';
 import { TableRenderer } from './TableRenderer.js';
 import { RenderInline } from './InlineMarkdownRenderer.js';
+import { useSettings } from '../contexts/SettingsContext.js';
 
 interface MarkdownDisplayProps {
   text: string;
@@ -298,6 +299,7 @@ const RenderCodeBlockInternal: React.FC<RenderCodeBlockProps> = ({
   availableTerminalHeight,
   terminalWidth,
 }) => {
+  const settings = useSettings();
   const MIN_LINES_FOR_MESSAGE = 1; // Minimum lines to show before the "generating more" message
   const RESERVED_LINES = 2; // Lines reserved for the message itself and potential padding
 
@@ -322,6 +324,8 @@ const RenderCodeBlockInternal: React.FC<RenderCodeBlockProps> = ({
         lang,
         availableTerminalHeight,
         terminalWidth - CODE_BLOCK_PREFIX_PADDING,
+        undefined,
+        settings,
       );
       return (
         <Box paddingLeft={CODE_BLOCK_PREFIX_PADDING} flexDirection="column">
@@ -338,6 +342,8 @@ const RenderCodeBlockInternal: React.FC<RenderCodeBlockProps> = ({
     lang,
     availableTerminalHeight,
     terminalWidth - CODE_BLOCK_PREFIX_PADDING,
+    undefined,
+    settings,
   );
 
   return (

packages/cli/src/ui/utils/__snapshots__/MarkdownDisplay.test.tsx.snap

@@ -23,6 +23,8 @@ exports[`<MarkdownDisplay /> > handles a table at the end of the input 1`] = `
 
 exports[`<MarkdownDisplay /> > handles unclosed (pending) code blocks 1`] = `" 1 let y = 2;"`;
 
+exports[`<MarkdownDisplay /> > hides line numbers in code blocks when showLineNumbers is false 1`] = `" const x = 1;"`;
+
 exports[`<MarkdownDisplay /> > inserts a single space between paragraphs 1`] = `
 "Paragraph 1.
 
@@ -87,3 +89,5 @@ exports[`<MarkdownDisplay /> > renders unordered lists with different markers 1`
  + item C
 "
 `;
+
+exports[`<MarkdownDisplay /> > shows line numbers in code blocks by default 1`] = `" 1 const x = 1;"`;