14 files changed, 923 insertions, 17 deletions
diff --git a/packages/cli/src/config/keyBindings.ts b/packages/cli/src/config/keyBindings.ts
index 6f4a21a2..640bf9de 100644
--- a/packages/cli/src/config/keyBindings.ts
+++ b/packages/cli/src/config/keyBindings.ts
@@ -129,20 +129,24 @@ export const defaultKeyBindings: KeyBindingConfig = {
 
   // Text input
   // Original: key.name === 'return' && !key.ctrl && !key.meta && !key.paste
+  // Must also exclude shift to allow shift+enter for newline
   [Command.SUBMIT]: [
     {
       key: 'return',
       ctrl: false,
       command: false,
       paste: false,
+      shift: false,
     },
   ],
   // Original: key.name === 'return' && (key.ctrl || key.meta || key.paste)
   // Split into multiple data-driven bindings
+  // Now also includes shift+enter for multi-line input
   [Command.NEWLINE]: [
     { key: 'return', ctrl: true },
     { key: 'return', command: true },
     { key: 'return', paste: true },
+    { key: 'return', shift: true },
   ],
 
   // External tools
diff --git a/packages/cli/src/gemini.tsx b/packages/cli/src/gemini.tsx
index 68f948da..54e58f72 100644
--- a/packages/cli/src/gemini.tsx
+++ b/packages/cli/src/gemini.tsx
@@ -41,6 +41,7 @@ import {
 import { validateAuthMethod } from './config/auth.js';
 import { setMaxSizedBoxDebugging } from './ui/components/shared/MaxSizedBox.js';
 import { validateNonInteractiveAuth } from './validateNonInterActiveAuth.js';
+import { detectAndEnableKittyProtocol } from './ui/utils/kittyProtocolDetector.js';
 import { checkForUpdates } from './ui/utils/updateCheck.js';
 import { handleAutoUpdate } from './utils/handleAutoUpdate.js';
 import { appEvents, AppEvent } from './utils/events.js';
@@ -263,6 +264,8 @@ export async function main() {
   // Render UI, passing necessary config values. Check that there is no command line question.
   if (config.isInteractive()) {
     const version = await getCliVersion();
+    // Detect and enable Kitty keyboard protocol once at startup
+    await detectAndEnableKittyProtocol();
     setWindowTitle(basename(workspaceRoot), settings);
     const instance = render(
       <React.StrictMode>
diff --git a/packages/cli/src/services/BuiltinCommandLoader.ts b/packages/cli/src/services/BuiltinCommandLoader.ts
index 639bb4d8..7a09cb14 100644
--- a/packages/cli/src/services/BuiltinCommandLoader.ts
+++ b/packages/cli/src/services/BuiltinCommandLoader.ts
@@ -33,6 +33,7 @@ import { toolsCommand } from '../ui/commands/toolsCommand.js';
 import { settingsCommand } from '../ui/commands/settingsCommand.js';
 import { vimCommand } from '../ui/commands/vimCommand.js';
 import { setupGithubCommand } from '../ui/commands/setupGithubCommand.js';
+import { terminalSetupCommand } from '../ui/commands/terminalSetupCommand.js';
 
 /**
  * Loads the core, hard-coded slash commands that are an integral part
@@ -76,6 +77,7 @@ export class BuiltinCommandLoader implements ICommandLoader {
       settingsCommand,
       vimCommand,
       setupGithubCommand,
+      terminalSetupCommand,
     ];
 
     return allDefinitions.filter((cmd): cmd is SlashCommand => cmd !== null);
diff --git a/packages/cli/src/ui/App.tsx b/packages/cli/src/ui/App.tsx
index 1caabbe0..e8aca549 100644
--- a/packages/cli/src/ui/App.tsx
+++ b/packages/cli/src/ui/App.tsx
@@ -80,6 +80,7 @@ import { useTextBuffer } from './components/shared/text-buffer.js';
 import { useVimMode, VimModeProvider } from './contexts/VimModeContext.js';
 import { useVim } from './hooks/vim.js';
 import { useKeypress, Key } from './hooks/useKeypress.js';
+import { useKittyKeyboardProtocol } from './hooks/useKittyKeyboardProtocol.js';
 import { keyMatchers, Command } from './keyMatchers.js';
 import * as fs from 'fs';
 import { UpdateNotification } from './components/UpdateNotification.js';
@@ -605,6 +606,7 @@ const App = ({ config, settings, startupWarnings = [], version }: AppProps) => {
   const { elapsedTime, currentLoadingPhrase } =
     useLoadingIndicator(streamingState);
   const showAutoAcceptIndicator = useAutoAcceptIndicator({ config });
+  const kittyProtocolStatus = useKittyKeyboardProtocol();
 
   const handleExit = useCallback(
     (
@@ -697,7 +699,11 @@ const App = ({ config, settings, startupWarnings = [], version }: AppProps) => {
     ],
   );
 
-  useKeypress(handleGlobalKeypress, { isActive: true });
+  useKeypress(handleGlobalKeypress, {
+    isActive: true,
+    kittyProtocolEnabled: kittyProtocolStatus.enabled,
+    config,
+  });
 
   useEffect(() => {
     if (config) {
diff --git a/packages/cli/src/ui/commands/terminalSetupCommand.test.ts b/packages/cli/src/ui/commands/terminalSetupCommand.test.ts
new file mode 100644
index 00000000..85f8735e
--- /dev/null
+++ b/packages/cli/src/ui/commands/terminalSetupCommand.test.ts
@@ -0,0 +1,85 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { terminalSetupCommand } from './terminalSetupCommand.js';
+import * as terminalSetupModule from '../utils/terminalSetup.js';
+import { CommandContext } from './types.js';
+
+vi.mock('../utils/terminalSetup.js');
+
+describe('terminalSetupCommand', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should have correct metadata', () => {
+    expect(terminalSetupCommand.name).toBe('terminal-setup');
+    expect(terminalSetupCommand.description).toContain('multiline input');
+    expect(terminalSetupCommand.kind).toBe('built-in');
+  });
+
+  it('should return success message when terminal setup succeeds', async () => {
+    vi.spyOn(terminalSetupModule, 'terminalSetup').mockResolvedValue({
+      success: true,
+      message: 'Terminal configured successfully',
+    });
+
+    const result = await terminalSetupCommand.action({} as CommandContext, '');
+
+    expect(result).toEqual({
+      type: 'message',
+      content: 'Terminal configured successfully',
+      messageType: 'info',
+    });
+  });
+
+  it('should append restart message when terminal setup requires restart', async () => {
+    vi.spyOn(terminalSetupModule, 'terminalSetup').mockResolvedValue({
+      success: true,
+      message: 'Terminal configured successfully',
+      requiresRestart: true,
+    });
+
+    const result = await terminalSetupCommand.action({} as CommandContext, '');
+
+    expect(result).toEqual({
+      type: 'message',
+      content:
+        'Terminal configured successfully\n\nPlease restart your terminal for the changes to take effect.',
+      messageType: 'info',
+    });
+  });
+
+  it('should return error message when terminal setup fails', async () => {
+    vi.spyOn(terminalSetupModule, 'terminalSetup').mockResolvedValue({
+      success: false,
+      message: 'Failed to detect terminal',
+    });
+
+    const result = await terminalSetupCommand.action({} as CommandContext, '');
+
+    expect(result).toEqual({
+      type: 'message',
+      content: 'Failed to detect terminal',
+      messageType: 'error',
+    });
+  });
+
+  it('should handle exceptions from terminal setup', async () => {
+    vi.spyOn(terminalSetupModule, 'terminalSetup').mockRejectedValue(
+      new Error('Unexpected error'),
+    );
+
+    const result = await terminalSetupCommand.action({} as CommandContext, '');
+
+    expect(result).toEqual({
+      type: 'message',
+      content: 'Failed to configure terminal: Error: Unexpected error',
+      messageType: 'error',
+    });
+  });
+});
diff --git a/packages/cli/src/ui/commands/terminalSetupCommand.ts b/packages/cli/src/ui/commands/terminalSetupCommand.ts
new file mode 100644
index 00000000..11520c0e
--- /dev/null
+++ b/packages/cli/src/ui/commands/terminalSetupCommand.ts
@@ -0,0 +1,45 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { MessageActionReturn, SlashCommand, CommandKind } from './types.js';
+import { terminalSetup } from '../utils/terminalSetup.js';
+
+/**
+ * Command to configure terminal keybindings for multiline input support.
+ *
+ * This command automatically detects and configures VS Code, Cursor, and Windsurf
+ * to support Shift+Enter and Ctrl+Enter for multiline input.
+ */
+export const terminalSetupCommand: SlashCommand = {
+  name: 'terminal-setup',
+  description:
+    'Configure terminal keybindings for multiline input (VS Code, Cursor, Windsurf)',
+  kind: CommandKind.BUILT_IN,
+
+  action: async (): Promise<MessageActionReturn> => {
+    try {
+      const result = await terminalSetup();
+
+      let content = result.message;
+      if (result.requiresRestart) {
+        content +=
+          '\n\nPlease restart your terminal for the changes to take effect.';
+      }
+
+      return {
+        type: 'message',
+        content,
+        messageType: result.success ? 'info' : 'error',
+      };
+    } catch (error) {
+      return {
+        type: 'message',
+        content: `Failed to configure terminal: ${error}`,
+        messageType: 'error',
+      };
+    }
+  },
+};
diff --git a/packages/cli/src/ui/components/InputPrompt.tsx b/packages/cli/src/ui/components/InputPrompt.tsx
index f53d255f..94cbcf1b 100644
--- a/packages/cli/src/ui/components/InputPrompt.tsx
+++ b/packages/cli/src/ui/components/InputPrompt.tsx
@@ -17,6 +17,7 @@ import { useShellHistory } from '../hooks/useShellHistory.js';
 import { useReverseSearchCompletion } from '../hooks/useReverseSearchCompletion.js';
 import { useCommandCompletion } from '../hooks/useCommandCompletion.js';
 import { useKeypress, Key } from '../hooks/useKeypress.js';
+import { useKittyKeyboardProtocol } from '../hooks/useKittyKeyboardProtocol.js';
 import { keyMatchers, Command } from '../keyMatchers.js';
 import { CommandContext, SlashCommand } from '../commands/types.js';
 import { Config } from '@google/gemini-cli-core';
@@ -66,6 +67,7 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
   const [escPressCount, setEscPressCount] = useState(0);
   const [showEscapePrompt, setShowEscapePrompt] = useState(false);
   const escapeTimerRef = useRef<NodeJS.Timeout | null>(null);
+  const kittyProtocolStatus = useKittyKeyboardProtocol();
 
   const [dirs, setDirs] = useState<readonly string[]>(
     config.getWorkspaceContext().getDirectories(),
@@ -525,7 +527,11 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
     ],
   );
 
-  useKeypress(handleInput, { isActive: true });
+  useKeypress(handleInput, {
+    isActive: true,
+    kittyProtocolEnabled: kittyProtocolStatus.enabled,
+    config,
+  });
 
   const linesToRender = buffer.viewportVisualLines;
   const [cursorVisualRowAbsolute, cursorVisualColAbsolute] =
diff --git a/packages/cli/src/ui/hooks/useFocus.ts b/packages/cli/src/ui/hooks/useFocus.ts
index 6c9a6daa..8a7f9f6c 100644
--- a/packages/cli/src/ui/hooks/useFocus.ts
+++ b/packages/cli/src/ui/hooks/useFocus.ts
@@ -8,12 +8,12 @@ import { useStdin, useStdout } from 'ink';
 import { useEffect, useState } from 'react';
 
 // ANSI escape codes to enable/disable terminal focus reporting
-const ENABLE_FOCUS_REPORTING = '\x1b[?1004h';
-const DISABLE_FOCUS_REPORTING = '\x1b[?1004l';
+export const ENABLE_FOCUS_REPORTING = '\x1b[?1004h';
+export const DISABLE_FOCUS_REPORTING = '\x1b[?1004l';
 
 // ANSI escape codes for focus events
-const FOCUS_IN = '\x1b[I';
-const FOCUS_OUT = '\x1b[O';
+export const FOCUS_IN = '\x1b[I';
+export const FOCUS_OUT = '\x1b[O';
 
 export const useFocus = () => {
   const { stdin } = useStdin();
diff --git a/packages/cli/src/ui/hooks/useKeypress.test.ts b/packages/cli/src/ui/hooks/useKeypress.test.ts
index a30eabf2..946ee054 100644
--- a/packages/cli/src/ui/hooks/useKeypress.test.ts
+++ b/packages/cli/src/ui/hooks/useKeypress.test.ts
@@ -134,9 +134,14 @@ describe('useKeypress', () => {
     expect(onKeypress).not.toHaveBeenCalled();
   });
 
-  it('should listen for keypress when active', () => {
+  it.each([
+    { key: { name: 'a', sequence: 'a' } },
+    { key: { name: 'left', sequence: '\x1b[D' } },
+    { key: { name: 'right', sequence: '\x1b[C' } },
+    { key: { name: 'up', sequence: '\x1b[A' } },
+    { key: { name: 'down', sequence: '\x1b[B' } },
+  ])('should listen for keypress when active for key $key.name', ({ key }) => {
     renderHook(() => useKeypress(onKeypress, { isActive: true }));
-    const key = { name: 'a', sequence: 'a' };
     act(() => stdin.pressKey(key));
     expect(onKeypress).toHaveBeenCalledWith(expect.objectContaining(key));
   });
@@ -187,7 +192,7 @@ describe('useKeypress', () => {
       },
       isLegacy: true,
     },
-  ])('Paste Handling in $description', ({ setup, isLegacy }) => {
+  ])('in $description', ({ setup, isLegacy }) => {
     beforeEach(() => {
       setup();
       stdin.setLegacy(isLegacy);
diff --git a/packages/cli/src/ui/hooks/useKeypress.ts b/packages/cli/src/ui/hooks/useKeypress.ts
index 6c2b7e8f..920270ee 100644
--- a/packages/cli/src/ui/hooks/useKeypress.ts
+++ b/packages/cli/src/ui/hooks/useKeypress.ts
@@ -8,6 +8,21 @@ import { useEffect, useRef } from 'react';
 import { useStdin } from 'ink';
 import readline from 'readline';
 import { PassThrough } from 'stream';
+import {
+  KITTY_CTRL_C,
+  BACKSLASH_ENTER_DETECTION_WINDOW_MS,
+  MAX_KITTY_SEQUENCE_LENGTH,
+} from '../utils/platformConstants.js';
+import {
+  KittySequenceOverflowEvent,
+  logKittySequenceOverflow,
+  Config,
+} from '@google/gemini-cli-core';
+import { FOCUS_IN, FOCUS_OUT } from './useFocus.js';
+
+const ESC = '\u001B';
+export const PASTE_MODE_PREFIX = `${ESC}[200~`;
+export const PASTE_MODE_SUFFIX = `${ESC}[201~`;
 
 export interface Key {
   name: string;
@@ -16,6 +31,7 @@ export interface Key {
   shift: boolean;
   paste: boolean;
   sequence: string;
+  kittyProtocol?: boolean;
 }
 
 /**
@@ -30,10 +46,16 @@ export interface Key {
  * @param onKeypress - The callback function to execute on each keypress.
  * @param options - Options to control the hook's behavior.
  * @param options.isActive - Whether the hook should be actively listening for input.
+ * @param options.kittyProtocolEnabled - Whether Kitty keyboard protocol is enabled.
+ * @param options.config - Optional config for telemetry logging.
  */
 export function useKeypress(
   onKeypress: (key: Key) => void,
-  { isActive }: { isActive: boolean },
+  {
+    isActive,
+    kittyProtocolEnabled = false,
+    config,
+  }: { isActive: boolean; kittyProtocolEnabled?: boolean; config?: Config },
 ) {
   const { stdin, setRawMode } = useStdin();
   const onKeypressRef = useRef(onKeypress);
@@ -64,8 +86,210 @@ export function useKeypress(
 
     let isPaste = false;
     let pasteBuffer = Buffer.alloc(0);
+    let kittySequenceBuffer = '';
+    let backslashTimeout: NodeJS.Timeout | null = null;
+    let waitingForEnterAfterBackslash = false;
+
+    // Parse Kitty protocol sequences
+    const parseKittySequence = (sequence: string): Key | null => {
+      // Match CSI <number> ; <modifiers> u or ~
+      // Format: ESC [ <keycode> ; <modifiers> u/~
+      const kittyPattern = new RegExp(`^${ESC}\\[(\\d+)(;(\\d+))?([u~])$`);
+      const match = sequence.match(kittyPattern);
+      if (!match) return null;
+
+      const keyCode = parseInt(match[1], 10);
+      const modifiers = match[3] ? parseInt(match[3], 10) : 1;
+
+      // Decode modifiers (subtract 1 as per Kitty protocol spec)
+      const modifierBits = modifiers - 1;
+      const shift = (modifierBits & 1) === 1;
+      const alt = (modifierBits & 2) === 2;
+      const ctrl = (modifierBits & 4) === 4;
+
+      // Handle Escape key (code 27)
+      if (keyCode === 27) {
+        return {
+          name: 'escape',
+          ctrl,
+          meta: alt,
+          shift,
+          paste: false,
+          sequence,
+          kittyProtocol: true,
+        };
+      }
+
+      // Handle Enter key (code 13)
+      if (keyCode === 13) {
+        return {
+          name: 'return',
+          ctrl,
+          meta: alt,
+          shift,
+          paste: false,
+          sequence,
+          kittyProtocol: true,
+        };
+      }
+
+      // Handle Ctrl+letter combinations (a-z)
+      // ASCII codes: a=97, b=98, c=99, ..., z=122
+      if (keyCode >= 97 && keyCode <= 122 && ctrl) {
+        const letter = String.fromCharCode(keyCode);
+        return {
+          name: letter,
+          ctrl: true,
+          meta: alt,
+          shift,
+          paste: false,
+          sequence,
+          kittyProtocol: true,
+        };
+      }
+
+      // Handle other keys as needed
+      return null;
+    };
 
     const handleKeypress = (_: unknown, key: Key) => {
+      // Handle VS Code's backslash+return pattern (Shift+Enter)
+      if (key.name === 'return' && waitingForEnterAfterBackslash) {
+        // Cancel the timeout since we got the Enter
+        if (backslashTimeout) {
+          clearTimeout(backslashTimeout);
+          backslashTimeout = null;
+        }
+        waitingForEnterAfterBackslash = false;
+
+        // Convert to Shift+Enter
+        onKeypressRef.current({
+          ...key,
+          shift: true,
+          sequence: '\\\r', // VS Code's Shift+Enter representation
+        });
+        return;
+      }
+
+      // Handle backslash - hold it to see if Enter follows
+      if (key.sequence === '\\' && !key.name) {
+        // Don't pass through the backslash yet - wait to see if Enter follows
+        waitingForEnterAfterBackslash = true;
+
+        // Set up a timeout to pass through the backslash if no Enter follows
+        backslashTimeout = setTimeout(() => {
+          waitingForEnterAfterBackslash = false;
+          backslashTimeout = null;
+          // Pass through the backslash since no Enter followed
+          onKeypressRef.current(key);
+        }, BACKSLASH_ENTER_DETECTION_WINDOW_MS);
+
+        return;
+      }
+
+      // If we're waiting for Enter after backslash but got something else,
+      // pass through the backslash first, then the new key
+      if (waitingForEnterAfterBackslash && key.name !== 'return') {
+        if (backslashTimeout) {
+          clearTimeout(backslashTimeout);
+          backslashTimeout = null;
+        }
+        waitingForEnterAfterBackslash = false;
+
+        // Pass through the backslash that was held
+        onKeypressRef.current({
+          name: '',
+          sequence: '\\',
+          ctrl: false,
+          meta: false,
+          shift: false,
+          paste: false,
+        });
+
+        // Then continue processing the current key normally
+      }
+
+      // If readline has already identified an arrow key, pass it through
+      // immediately, bypassing the Kitty protocol sequence buffering.
+      if (['up', 'down', 'left', 'right'].includes(key.name)) {
+        onKeypressRef.current(key);
+        return;
+      }
+
+      // Always pass through Ctrl+C immediately, regardless of protocol state
+      // Check both standard format and Kitty protocol sequence
+      if (
+        (key.ctrl && key.name === 'c') ||
+        key.sequence === `${ESC}${KITTY_CTRL_C}`
+      ) {
+        kittySequenceBuffer = '';
+        // If it's the Kitty sequence, create a proper key object
+        if (key.sequence === `${ESC}${KITTY_CTRL_C}`) {
+          onKeypressRef.current({
+            name: 'c',
+            ctrl: true,
+            meta: false,
+            shift: false,
+            paste: false,
+            sequence: key.sequence,
+            kittyProtocol: true,
+          });
+        } else {
+          onKeypressRef.current(key);
+        }
+        return;
+      }
+
+      // If Kitty protocol is enabled, handle CSI sequences
+      if (kittyProtocolEnabled) {
+        // If we have a buffer or this starts a CSI sequence
+        if (
+          kittySequenceBuffer ||
+          (key.sequence.startsWith(`${ESC}[`) &&
+            !key.sequence.startsWith(PASTE_MODE_PREFIX) &&
+            !key.sequence.startsWith(PASTE_MODE_SUFFIX) &&
+            !key.sequence.startsWith(FOCUS_IN) &&
+            !key.sequence.startsWith(FOCUS_OUT))
+        ) {
+          kittySequenceBuffer += key.sequence;
+
+          // Try to parse the buffer as a Kitty sequence
+          const kittyKey = parseKittySequence(kittySequenceBuffer);
+          if (kittyKey) {
+            kittySequenceBuffer = '';
+            onKeypressRef.current(kittyKey);
+            return;
+          }
+
+          if (config?.getDebugMode()) {
+            const codes = Array.from(kittySequenceBuffer).map((ch) =>
+              ch.charCodeAt(0),
+            );
+            // Unless the user is sshing over a slow connection, this likely
+            // indicates this is not a kitty sequence but we have incorrectly
+            // interpreted it as such. See the examples above for sequences
+            // such as FOCUS_IN that are not Kitty sequences.
+            console.warn('Kitty sequence buffer has char codes:', codes);
+          }
+
+          // If buffer doesn't match expected pattern and is getting long, flush it
+          if (kittySequenceBuffer.length > MAX_KITTY_SEQUENCE_LENGTH) {
+            // Log telemetry for buffer overflow
+            if (config) {
+              const event = new KittySequenceOverflowEvent(
+                kittySequenceBuffer.length,
+                kittySequenceBuffer,
+              );
+              logKittySequenceOverflow(config, event);
+            }
+            // Not a Kitty sequence, treat as regular key
+            kittySequenceBuffer = '';
+          } else {
+            // Wait for more characters
+            return;
+          }
+        }
+      }
       if (key.name === 'paste-start') {
         isPaste = true;
       } else if (key.name === 'paste-end') {
@@ -84,7 +308,7 @@ export function useKeypress(
           pasteBuffer = Buffer.concat([pasteBuffer, Buffer.from(key.sequence)]);
         } else {
           // Handle special keys
-          if (key.name === 'return' && key.sequence === '\x1B\r') {
+          if (key.name === 'return' && key.sequence === `${ESC}\r`) {
             key.meta = true;
           }
           onKeypressRef.current({ ...key, paste: isPaste });
@@ -93,13 +317,13 @@ export function useKeypress(
     };
 
     const handleRawKeypress = (data: Buffer) => {
-      const PASTE_MODE_PREFIX = Buffer.from('\x1B[200~');
-      const PASTE_MODE_SUFFIX = Buffer.from('\x1B[201~');
+      const pasteModePrefixBuffer = Buffer.from(PASTE_MODE_PREFIX);
+      const pasteModeSuffixBuffer = Buffer.from(PASTE_MODE_SUFFIX);
 
       let pos = 0;
       while (pos < data.length) {
-        const prefixPos = data.indexOf(PASTE_MODE_PREFIX, pos);
-        const suffixPos = data.indexOf(PASTE_MODE_SUFFIX, pos);
+        const prefixPos = data.indexOf(pasteModePrefixBuffer, pos);
+        const suffixPos = data.indexOf(pasteModeSuffixBuffer, pos);
 
         // Determine which marker comes first, if any.
         const isPrefixNext =
@@ -115,7 +339,7 @@ export function useKeypress(
         } else if (isSuffixNext) {
           nextMarkerPos = suffixPos;
         }
-        markerLength = PASTE_MODE_SUFFIX.length;
+        markerLength = pasteModeSuffixBuffer.length;
 
         if (nextMarkerPos === -1) {
           keypressStream.write(data.slice(pos));
@@ -170,6 +394,12 @@ export function useKeypress(
       rl.close();
       setRawMode(false);
 
+      // Clean up any pending backslash timeout
+      if (backslashTimeout) {
+        clearTimeout(backslashTimeout);
+        backslashTimeout = null;
+      }
+
       // If we are in the middle of a paste, send what we have.
       if (isPaste) {
         onKeypressRef.current({
@@ -183,5 +413,5 @@ export function useKeypress(
         pasteBuffer = Buffer.alloc(0);
       }
     };
-  }, [isActive, stdin, setRawMode]);
+  }, [isActive, stdin, setRawMode, kittyProtocolEnabled, config]);
 }
diff --git a/packages/cli/src/ui/hooks/useKittyKeyboardProtocol.ts b/packages/cli/src/ui/hooks/useKittyKeyboardProtocol.ts
new file mode 100644
index 00000000..53c7566c
--- /dev/null
+++ b/packages/cli/src/ui/hooks/useKittyKeyboardProtocol.ts
@@ -0,0 +1,31 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { useState } from 'react';
+import {
+  isKittyProtocolEnabled,
+  isKittyProtocolSupported,
+} from '../utils/kittyProtocolDetector.js';
+
+export interface KittyProtocolStatus {
+  supported: boolean;
+  enabled: boolean;
+  checking: boolean;
+}
+
+/**
+ * Hook that returns the cached Kitty keyboard protocol status.
+ * Detection is done once at app startup to avoid repeated queries.
+ */
+export function useKittyKeyboardProtocol(): KittyProtocolStatus {
+  const [status] = useState<KittyProtocolStatus>({
+    supported: isKittyProtocolSupported(),
+    enabled: isKittyProtocolEnabled(),
+    checking: false,
+  });
+
+  return status;
+}
diff --git a/packages/cli/src/ui/utils/kittyProtocolDetector.ts b/packages/cli/src/ui/utils/kittyProtocolDetector.ts
new file mode 100644
index 00000000..5d77943a
--- /dev/null
+++ b/packages/cli/src/ui/utils/kittyProtocolDetector.ts
@@ -0,0 +1,105 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+let detectionComplete = false;
+let protocolSupported = false;
+let protocolEnabled = false;
+
+/**
+ * Detects Kitty keyboard protocol support.
+ * Definitive document about this protocol lives at https://sw.kovidgoyal.net/kitty/keyboard-protocol/
+ * This function should be called once at app startup.
+ */
+export async function detectAndEnableKittyProtocol(): Promise<boolean> {
+  if (detectionComplete) {
+    return protocolSupported;
+  }
+
+  return new Promise((resolve) => {
+    if (!process.stdin.isTTY || !process.stdout.isTTY) {
+      detectionComplete = true;
+      resolve(false);
+      return;
+    }
+
+    const originalRawMode = process.stdin.isRaw;
+    if (!originalRawMode) {
+      process.stdin.setRawMode(true);
+    }
+
+    let responseBuffer = '';
+    let progressiveEnhancementReceived = false;
+    let checkFinished = false;
+
+    const handleData = (data: Buffer) => {
+      responseBuffer += data.toString();
+
+      // Check for progressive enhancement response (CSI ? <flags> u)
+      if (responseBuffer.includes('\x1b[?') && responseBuffer.includes('u')) {
+        progressiveEnhancementReceived = true;
+      }
+
+      // Check for device attributes response (CSI ? <attrs> c)
+      if (responseBuffer.includes('\x1b[?') && responseBuffer.includes('c')) {
+        if (!checkFinished) {
+          checkFinished = true;
+          process.stdin.removeListener('data', handleData);
+
+          if (!originalRawMode) {
+            process.stdin.setRawMode(false);
+          }
+
+          if (progressiveEnhancementReceived) {
+            // Enable the protocol
+            process.stdout.write('\x1b[>1u');
+            protocolSupported = true;
+            protocolEnabled = true;
+
+            // Set up cleanup on exit
+            process.on('exit', disableProtocol);
+            process.on('SIGTERM', disableProtocol);
+          }
+
+          detectionComplete = true;
+          resolve(protocolSupported);
+        }
+      }
+    };
+
+    process.stdin.on('data', handleData);
+
+    // Send queries
+    process.stdout.write('\x1b[?u'); // Query progressive enhancement
+    process.stdout.write('\x1b[c'); // Query device attributes
+
+    // Timeout after 50ms
+    setTimeout(() => {
+      if (!checkFinished) {
+        process.stdin.removeListener('data', handleData);
+        if (!originalRawMode) {
+          process.stdin.setRawMode(false);
+        }
+        detectionComplete = true;
+        resolve(false);
+      }
+    }, 50);
+  });
+}
+
+function disableProtocol() {
+  if (protocolEnabled) {
+    process.stdout.write('\x1b[<u');
+    protocolEnabled = false;
+  }
+}
+
+export function isKittyProtocolEnabled(): boolean {
+  return protocolEnabled;
+}
+
+export function isKittyProtocolSupported(): boolean {
+  return protocolSupported;
+}
diff --git a/packages/cli/src/ui/utils/platformConstants.ts b/packages/cli/src/ui/utils/platformConstants.ts
new file mode 100644
index 00000000..9d2e1990
--- /dev/null
+++ b/packages/cli/src/ui/utils/platformConstants.ts
@@ -0,0 +1,44 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Terminal Platform Constants
+ *
+ * This file contains terminal-related constants used throughout the application,
+ * specifically for handling keyboard inputs and terminal protocols.
+ */
+
+/**
+ * Kitty keyboard protocol sequences for enhanced keyboard input.
+ * @see https://sw.kovidgoyal.net/kitty/keyboard-protocol/
+ */
+export const KITTY_CTRL_C = '[99;5u';
+
+/**
+ * Timing constants for terminal interactions
+ */
+export const CTRL_EXIT_PROMPT_DURATION_MS = 1000;
+
+/**
+ * VS Code terminal integration constants
+ */
+export const VSCODE_SHIFT_ENTER_SEQUENCE = '\\\r\n';
+
+/**
+ * Backslash + Enter detection window in milliseconds.
+ * Used to detect Shift+Enter pattern where backslash
+ * is followed by Enter within this timeframe.
+ */
+export const BACKSLASH_ENTER_DETECTION_WINDOW_MS = 5;
+
+/**
+ * Maximum expected length of a Kitty keyboard protocol sequence.
+ * Format: ESC [ <keycode> ; <modifiers> u/~
+ * Example: \x1b[13;2u (Shift+Enter) = 8 chars
+ * Longest reasonable: \x1b[127;15~ = 11 chars (Del with all modifiers)
+ * We use 12 to provide a small buffer.
+ */
+export const MAX_KITTY_SEQUENCE_LENGTH = 12;
diff --git a/packages/cli/src/ui/utils/terminalSetup.ts b/packages/cli/src/ui/utils/terminalSetup.ts
new file mode 100644
index 00000000..7f944847
--- /dev/null
+++ b/packages/cli/src/ui/utils/terminalSetup.ts
@@ -0,0 +1,340 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Terminal setup utility for configuring Shift+Enter and Ctrl+Enter support.
+ *
+ * This module provides automatic detection and configuration of various terminal
+ * emulators to support multiline input through modified Enter keys.
+ *
+ * Supported terminals:
+ * - VS Code: Configures keybindings.json to send \\\r\n
+ * - Cursor: Configures keybindings.json to send \\\r\n (VS Code fork)
+ * - Windsurf: Configures keybindings.json to send \\\r\n (VS Code fork)
+ *
+ * For VS Code and its forks:
+ * - Shift+Enter: Sends \\\r\n (backslash followed by CRLF)
+ * - Ctrl+Enter: Sends \\\r\n (backslash followed by CRLF)
+ *
+ * The module will not modify existing shift+enter or ctrl+enter keybindings
+ * to avoid conflicts with user customizations.
+ */
+
+import { promises as fs } from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+import { exec } from 'child_process';
+import { promisify } from 'util';
+import { isKittyProtocolEnabled } from './kittyProtocolDetector.js';
+import { VSCODE_SHIFT_ENTER_SEQUENCE } from './platformConstants.js';
+
+const execAsync = promisify(exec);
+
+/**
+ * Removes single-line JSON comments (// ...) from a string to allow parsing
+ * VS Code style JSON files that may contain comments.
+ */
+function stripJsonComments(content: string): string {
+  // Remove single-line comments (// ...)
+  return content.replace(/^\s*\/\/.*$/gm, '');
+}
+
+export interface TerminalSetupResult {
+  success: boolean;
+  message: string;
+  requiresRestart?: boolean;
+}
+
+type SupportedTerminal = 'vscode' | 'cursor' | 'windsurf';
+
+// Terminal detection
+async function detectTerminal(): Promise<SupportedTerminal | null> {
+  const termProgram = process.env.TERM_PROGRAM;
+
+  // Check VS Code and its forks - check forks first to avoid false positives
+  // Check for Cursor-specific indicators
+  if (
+    process.env.CURSOR_TRACE_ID ||
+    process.env.VSCODE_GIT_ASKPASS_MAIN?.toLowerCase().includes('cursor')
+  ) {
+    return 'cursor';
+  }
+  // Check for Windsurf-specific indicators
+  if (process.env.VSCODE_GIT_ASKPASS_MAIN?.toLowerCase().includes('windsurf')) {
+    return 'windsurf';
+  }
+  // Check VS Code last since forks may also set VSCODE env vars
+  if (termProgram === 'vscode' || process.env.VSCODE_GIT_IPC_HANDLE) {
+    return 'vscode';
+  }
+
+  // Check parent process name
+  if (os.platform() !== 'win32') {
+    try {
+      const { stdout } = await execAsync('ps -o comm= -p $PPID');
+      const parentName = stdout.trim();
+
+      // Check forks before VS Code to avoid false positives
+      if (parentName.includes('windsurf') || parentName.includes('Windsurf'))
+        return 'windsurf';
+      if (parentName.includes('cursor') || parentName.includes('Cursor'))
+        return 'cursor';
+      if (parentName.includes('code') || parentName.includes('Code'))
+        return 'vscode';
+    } catch (error) {
+      // Continue detection even if process check fails
+      console.debug('Parent process detection failed:', error);
+    }
+  }
+
+  return null;
+}
+
+// Backup file helper
+async function backupFile(filePath: string): Promise<void> {
+  try {
+    const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
+    const backupPath = `${filePath}.backup.${timestamp}`;
+    await fs.copyFile(filePath, backupPath);
+  } catch (error) {
+    // Log backup errors but continue with operation
+    console.warn(`Failed to create backup of ${filePath}:`, error);
+  }
+}
+
+// Helper function to get VS Code-style config directory
+function getVSCodeStyleConfigDir(appName: string): string | null {
+  const platform = os.platform();
+
+  if (platform === 'darwin') {
+    return path.join(
+      os.homedir(),
+      'Library',
+      'Application Support',
+      appName,
+      'User',
+    );
+  } else if (platform === 'win32') {
+    if (!process.env.APPDATA) {
+      return null;
+    }
+    return path.join(process.env.APPDATA, appName, 'User');
+  } else {
+    return path.join(os.homedir(), '.config', appName, 'User');
+  }
+}
+
+// Generic VS Code-style terminal configuration
+async function configureVSCodeStyle(
+  terminalName: string,
+  appName: string,
+): Promise<TerminalSetupResult> {
+  const configDir = getVSCodeStyleConfigDir(appName);
+
+  if (!configDir) {
+    return {
+      success: false,
+      message: `Could not determine ${terminalName} config path on Windows: APPDATA environment variable is not set.`,
+    };
+  }
+
+  const keybindingsFile = path.join(configDir, 'keybindings.json');
+
+  try {
+    await fs.mkdir(configDir, { recursive: true });
+
+    let keybindings: unknown[] = [];
+    try {
+      const content = await fs.readFile(keybindingsFile, 'utf8');
+      await backupFile(keybindingsFile);
+      try {
+        const cleanContent = stripJsonComments(content);
+        const parsedContent = JSON.parse(cleanContent);
+        if (!Array.isArray(parsedContent)) {
+          return {
+            success: false,
+            message:
+              `${terminalName} keybindings.json exists but is not a valid JSON array. ` +
+              `Please fix the file manually or delete it to allow automatic configuration.\n` +
+              `File: ${keybindingsFile}`,
+          };
+        }
+        keybindings = parsedContent;
+      } catch (parseError) {
+        return {
+          success: false,
+          message:
+            `Failed to parse ${terminalName} keybindings.json. The file contains invalid JSON.\n` +
+            `Please fix the file manually or delete it to allow automatic configuration.\n` +
+            `File: ${keybindingsFile}\n` +
+            `Error: ${parseError}`,
+        };
+      }
+    } catch {
+      // File doesn't exist, will create new one
+    }
+
+    const shiftEnterBinding = {
+      key: 'shift+enter',
+      command: 'workbench.action.terminal.sendSequence',
+      when: 'terminalFocus',
+      args: { text: VSCODE_SHIFT_ENTER_SEQUENCE },
+    };
+
+    const ctrlEnterBinding = {
+      key: 'ctrl+enter',
+      command: 'workbench.action.terminal.sendSequence',
+      when: 'terminalFocus',
+      args: { text: VSCODE_SHIFT_ENTER_SEQUENCE },
+    };
+
+    // Check if ANY shift+enter or ctrl+enter bindings already exist
+    const existingShiftEnter = keybindings.find((kb) => {
+      const binding = kb as { key?: string };
+      return binding.key === 'shift+enter';
+    });
+
+    const existingCtrlEnter = keybindings.find((kb) => {
+      const binding = kb as { key?: string };
+      return binding.key === 'ctrl+enter';
+    });
+
+    if (existingShiftEnter || existingCtrlEnter) {
+      const messages: string[] = [];
+      if (existingShiftEnter) {
+        messages.push(`- Shift+Enter binding already exists`);
+      }
+      if (existingCtrlEnter) {
+        messages.push(`- Ctrl+Enter binding already exists`);
+      }
+      return {
+        success: false,
+        message:
+          `Existing keybindings detected. Will not modify to avoid conflicts.\n` +
+          messages.join('\n') +
+          '\n' +
+          `Please check and modify manually if needed: ${keybindingsFile}`,
+      };
+    }
+
+    // Check if our specific bindings already exist
+    const hasOurShiftEnter = keybindings.some((kb) => {
+      const binding = kb as {
+        command?: string;
+        args?: { text?: string };
+        key?: string;
+      };
+      return (
+        binding.key === 'shift+enter' &&
+        binding.command === 'workbench.action.terminal.sendSequence' &&
+        binding.args?.text === '\\\r\n'
+      );
+    });
+
+    const hasOurCtrlEnter = keybindings.some((kb) => {
+      const binding = kb as {
+        command?: string;
+        args?: { text?: string };
+        key?: string;
+      };
+      return (
+        binding.key === 'ctrl+enter' &&
+        binding.command === 'workbench.action.terminal.sendSequence' &&
+        binding.args?.text === '\\\r\n'
+      );
+    });
+
+    if (!hasOurShiftEnter || !hasOurCtrlEnter) {
+      if (!hasOurShiftEnter) keybindings.unshift(shiftEnterBinding);
+      if (!hasOurCtrlEnter) keybindings.unshift(ctrlEnterBinding);
+
+      await fs.writeFile(keybindingsFile, JSON.stringify(keybindings, null, 4));
+      return {
+        success: true,
+        message: `Added Shift+Enter and Ctrl+Enter keybindings to ${terminalName}.\nModified: ${keybindingsFile}`,
+        requiresRestart: true,
+      };
+    } else {
+      return {
+        success: true,
+        message: `${terminalName} keybindings already configured.`,
+      };
+    }
+  } catch (error) {
+    return {
+      success: false,
+      message: `Failed to configure ${terminalName}.\nFile: ${keybindingsFile}\nError: ${error}`,
+    };
+  }
+}
+
+// Terminal-specific configuration functions
+
+async function configureVSCode(): Promise<TerminalSetupResult> {
+  return configureVSCodeStyle('VS Code', 'Code');
+}
+
+async function configureCursor(): Promise<TerminalSetupResult> {
+  return configureVSCodeStyle('Cursor', 'Cursor');
+}
+
+async function configureWindsurf(): Promise<TerminalSetupResult> {
+  return configureVSCodeStyle('Windsurf', 'Windsurf');
+}
+
+/**
+ * Main terminal setup function that detects and configures the current terminal.
+ *
+ * This function:
+ * 1. Detects the current terminal emulator
+ * 2. Applies appropriate configuration for Shift+Enter and Ctrl+Enter support
+ * 3. Creates backups of configuration files before modifying them
+ *
+ * @returns Promise<TerminalSetupResult> Result object with success status and message
+ *
+ * @example
+ * const result = await terminalSetup();
+ * if (result.success) {
+ *   console.log(result.message);
+ *   if (result.requiresRestart) {
+ *     console.log('Please restart your terminal');
+ *   }
+ * }
+ */
+export async function terminalSetup(): Promise<TerminalSetupResult> {
+  // Check if terminal already has optimal keyboard support
+  if (isKittyProtocolEnabled()) {
+    return {
+      success: true,
+      message:
+        'Your terminal is already configured for an optimal experience with multiline input (Shift+Enter and Ctrl+Enter).',
+    };
+  }
+
+  const terminal = await detectTerminal();
+
+  if (!terminal) {
+    return {
+      success: false,
+      message:
+        'Could not detect terminal type. Supported terminals: VS Code, Cursor, and Windsurf.',
+    };
+  }
+
+  switch (terminal) {
+    case 'vscode':
+      return configureVSCode();
+    case 'cursor':
+      return configureCursor();
+    case 'windsurf':
+      return configureWindsurf();
+    default:
+      return {
+        success: false,
+        message: `Terminal "${terminal}" is not supported yet.`,
+      };
+  }
+}