fix(cli): escape @ symbols on paste to prevent unintended file expansion (#21239)

packages/cli/src/config/settingsSchema.ts

@@ -540,6 +540,16 @@ const SETTINGS_SCHEMA = {
         description: 'Hide helpful tips in the UI',
         showInDialog: true,
       },
+      escapePastedAtSymbols: {
+        type: 'boolean',
+        label: 'Escape Pasted @ Symbols',
+        category: 'UI',
+        requiresRestart: false,
+        default: false,
+        description:
+          'When enabled, @ symbols in pasted text are escaped to prevent unintended @path expansion.',
+        showInDialog: true,
+      },
       showShortcutsHint: {
         type: 'boolean',
         label: 'Show Shortcuts Hint',

packages/cli/src/nonInteractiveCli.ts

@@ -263,8 +263,8 @@ export async function runNonInteractive({
           onDebugMessage: () => {},
           messageId: Date.now(),
           signal: abortController.signal,
+          escapePastedAtSymbols: false,
         });
-
         if (error || !processedQuery) {
           // An error occurred during @include processing (e.g., file not found).
           // The error message is already logged by handleAtCommand.

packages/cli/src/ui/components/InputPrompt.tsx

@@ -11,6 +11,7 @@ import { Box, Text, useStdout, type DOMElement } from 'ink';
 import { SuggestionsDisplay, MAX_WIDTH } from './SuggestionsDisplay.js';
 import { theme } from '../semantic-colors.js';
 import { useInputHistory } from '../hooks/useInputHistory.js';
+import { escapeAtSymbols } from '../hooks/atCommandProcessor.js';
 import { HalfLinePaddedBox } from './shared/HalfLinePaddedBox.js';
 import {
   type TextBuffer,
@@ -515,7 +516,11 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
         stdout.write('\x1b]52;c;?\x07');
       } else {
         const textToInsert = await clipboardy.read();
-        buffer.insert(textToInsert, { paste: true });
+        const escapedText = settings.ui?.escapePastedAtSymbols
+          ? escapeAtSymbols(textToInsert)
+          : textToInsert;
+        buffer.insert(escapedText, { paste: true });
+
         if (isLargePaste(textToInsert)) {
           appEvents.emit(AppEvent.TransientMessage, {
             message: `Press ${formatCommand(Command.EXPAND_PASTE)} to expand pasted text`,
@@ -750,8 +755,15 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
             pasteTimeoutRef.current = null;
           }, 40);
         }
-        // Ensure we never accidentally interpret paste as regular input.
-        buffer.handleInput(key);
+        if (settings.ui?.escapePastedAtSymbols) {
+          buffer.handleInput({
+            ...key,
+            sequence: escapeAtSymbols(key.sequence || ''),
+          });
+        } else {
+          buffer.handleInput(key);
+        }
+
         if (key.sequence && isLargePaste(key.sequence)) {
           appEvents.emit(AppEvent.TransientMessage, {
             message: `Press ${formatCommand(Command.EXPAND_PASTE)} to expand pasted text`,
@@ -1291,6 +1303,7 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
       forceShowShellSuggestions,
       keyMatchers,
       isHelpDismissKey,
+      settings,
     ],
   );
 

packages/cli/src/ui/hooks/atCommandProcessor.test.ts

@@ -13,7 +13,11 @@ import {
   afterEach,
   type Mock,
 } from 'vitest';
-import { handleAtCommand } from './atCommandProcessor.js';
+import {
+  handleAtCommand,
+  escapeAtSymbols,
+  unescapeLiteralAt,
+} from './atCommandProcessor.js';
 import {
   FileDiscoveryService,
   GlobTool,
@@ -1481,3 +1485,56 @@ describe('handleAtCommand', () => {
     );
   });
 });
+
+describe('escapeAtSymbols', () => {
+  it('escapes a bare @ symbol', () => {
+    expect(escapeAtSymbols('test@domain.com')).toBe('test\\@domain.com');
+  });
+
+  it('escapes a leading @ symbol', () => {
+    expect(escapeAtSymbols('@scope/pkg')).toBe('\\@scope/pkg');
+  });
+
+  it('escapes multiple @ symbols', () => {
+    expect(escapeAtSymbols('a@b and c@d')).toBe('a\\@b and c\\@d');
+  });
+
+  it('does not double-escape an already escaped @', () => {
+    expect(escapeAtSymbols('test\\@domain.com')).toBe('test\\@domain.com');
+  });
+
+  it('returns text with no @ unchanged', () => {
+    expect(escapeAtSymbols('hello world')).toBe('hello world');
+  });
+
+  it('returns empty string unchanged', () => {
+    expect(escapeAtSymbols('')).toBe('');
+  });
+});
+
+describe('unescapeLiteralAt', () => {
+  it('unescapes \\@ to @', () => {
+    expect(unescapeLiteralAt('test\\@domain.com')).toBe('test@domain.com');
+  });
+
+  it('unescapes a leading \\@', () => {
+    expect(unescapeLiteralAt('\\@scope/pkg')).toBe('@scope/pkg');
+  });
+
+  it('unescapes multiple \\@ sequences', () => {
+    expect(unescapeLiteralAt('a\\@b and c\\@d')).toBe('a@b and c@d');
+  });
+
+  it('returns text with no \\@ unchanged', () => {
+    expect(unescapeLiteralAt('hello world')).toBe('hello world');
+  });
+
+  it('returns empty string unchanged', () => {
+    expect(unescapeLiteralAt('')).toBe('');
+  });
+
+  it('roundtrips correctly with escapeAtSymbols', () => {
+    const input = 'user@example.com and @scope/pkg';
+    expect(unescapeLiteralAt(escapeAtSymbols(input))).toBe(input);
+  });
+});

packages/cli/src/ui/hooks/atCommandProcessor.ts

@@ -30,6 +30,26 @@ import type { UseHistoryManagerReturn } from './useHistoryManager.js';
 const REF_CONTENT_HEADER = `\n${REFERENCE_CONTENT_START}`;
 const REF_CONTENT_FOOTER = `\n${REFERENCE_CONTENT_END}`;
 
+/**
+ * Escapes unescaped @ symbols so they are not interpreted as @path commands.
+ */
+export function escapeAtSymbols(text: string): string {
+  return text.replace(/(?<!\\)@/g, '\\@');
+}
+
+/**
+ * Unescapes \@ back to @ correctly, preserving \\@ sequences.
+ */
+export function unescapeLiteralAt(text: string): string {
+  return text.replace(/\\@/g, (match, offset, full) => {
+    let backslashCount = 0;
+    for (let i = offset - 1; i >= 0 && full[i] === '\\'; i--) {
+      backslashCount++;
+    }
+    return backslashCount % 2 === 0 ? '@' : '\\@';
+  });
+}
+
 /**
  * Regex source for the path/command part of an @ reference.
  * It uses strict ASCII whitespace delimiters to allow Unicode characters like NNBSP in filenames.
@@ -49,6 +69,7 @@ interface HandleAtCommandParams {
   onDebugMessage: (message: string) => void;
   messageId: number;
   signal: AbortSignal;
+  escapePastedAtSymbols?: boolean;
 }
 
 interface HandleAtCommandResult {
@@ -65,7 +86,10 @@ interface AtCommandPart {
  * Parses a query string to find all '@<path>' commands and text segments.
  * Handles \ escaped spaces within paths.
  */
-function parseAllAtCommands(query: string): AtCommandPart[] {
+function parseAllAtCommands(
+  query: string,
+  escapePastedAtSymbols = false,
+): AtCommandPart[] {
   const parts: AtCommandPart[] = [];
   let lastIndex = 0;
 
@@ -85,7 +109,9 @@ function parseAllAtCommands(query: string): AtCommandPart[] {
     if (matchIndex > lastIndex) {
       parts.push({
         type: 'text',
-        content: query.substring(lastIndex, matchIndex),
+        content: escapePastedAtSymbols
+          ? unescapeLiteralAt(query.substring(lastIndex, matchIndex))
+          : query.substring(lastIndex, matchIndex),
       });
     }
 
@@ -98,7 +124,12 @@ function parseAllAtCommands(query: string): AtCommandPart[] {
 
   // Add remaining text
   if (lastIndex < query.length) {
-    parts.push({ type: 'text', content: query.substring(lastIndex) });
+    parts.push({
+      type: 'text',
+      content: escapePastedAtSymbols
+        ? unescapeLiteralAt(query.substring(lastIndex))
+        : query.substring(lastIndex),
+    });
   }
 
   // Filter out empty text parts that might result from consecutive @paths or leading/trailing spaces
@@ -635,8 +666,9 @@ export async function handleAtCommand({
   onDebugMessage,
   messageId: userMessageTimestamp,
   signal,
+  escapePastedAtSymbols = false,
 }: HandleAtCommandParams): Promise<HandleAtCommandResult> {
-  const commandParts = parseAllAtCommands(query);
+  const commandParts = parseAllAtCommands(query, escapePastedAtSymbols);
 
   const { agentParts, resourceParts, fileParts } = categorizeAtCommands(
     commandParts,

packages/cli/src/ui/hooks/useGeminiStream.ts

@@ -837,8 +837,8 @@ export const useGeminiStream = (
             onDebugMessage,
             messageId: userMessageTimestamp,
             signal: abortSignal,
+            escapePastedAtSymbols: settings.merged.ui?.escapePastedAtSymbols,
           });
-
           if (atCommandResult.error) {
             onDebugMessage(atCommandResult.error);
             return { queryToSend: null, shouldProceed: false };
@@ -874,6 +874,7 @@ export const useGeminiStream = (
       logger,
       shellModeActive,
       scheduleToolCalls,
+      settings,
     ],
   );
 

packages/cli/src/ui/utils/highlight.ts

@@ -25,7 +25,7 @@ export type HighlightToken = {
 // It matches any character except strict delimiters (ASCII whitespace, comma, etc.).
 // This supports URIs like `@file:///example.txt` and filenames with Unicode spaces (like NNBSP).
 const HIGHLIGHT_REGEX = new RegExp(
-  `(^/[a-zA-Z0-9_-]+|@${AT_COMMAND_PATH_REGEX_SOURCE}|${PASTED_TEXT_PLACEHOLDER_REGEX.source})`,
+  `(^/[a-zA-Z0-9_-]+|(?<!\\\\)@${AT_COMMAND_PATH_REGEX_SOURCE}|${PASTED_TEXT_PLACEHOLDER_REGEX.source})`,
   'g',
 );