Multiline editor (#302)

Co-authored-by: Taylor Mullen <ntaylormullen@google.com>

packages/cli/src/ui/App.tsx

@@ -13,7 +13,7 @@ import { useInputHistory } from './hooks/useInputHistory.js';
 import { useThemeCommand } from './hooks/useThemeCommand.js';
 import { Header } from './components/Header.js';
 import { LoadingIndicator } from './components/LoadingIndicator.js';
-import { InputPrompt } from './components/InputPrompt.js';
+import { EditorState, InputPrompt } from './components/InputPrompt.js';
 import { Footer } from './components/Footer.js';
 import { ThemeDialog } from './components/ThemeDialog.js';
 import { useStartupWarnings } from './hooks/useAppEffects.js';
@@ -97,8 +97,22 @@ export const App = ({ config, settings, cliVersion }: AppProps) => {
 
   const isInputActive = streamingState === StreamingState.Idle && !initError;
 
-  // query and setQuery are now managed by useState here
   const [query, setQuery] = useState('');
+  const [editorState, setEditorState] = useState<EditorState>({
+    key: 0,
+    initialCursorOffset: undefined,
+  });
+
+  const onChangeAndMoveCursor = useCallback(
+    (value: string) => {
+      setQuery(value);
+      setEditorState((s) => ({
+        key: s.key + 1,
+        initialCursorOffset: value.length,
+      }));
+    },
+    [setQuery, setEditorState],
+  );
 
   const completion = useCompletion(
     query,
@@ -107,20 +121,16 @@ export const App = ({ config, settings, cliVersion }: AppProps) => {
     slashCommands,
   );
 
-  const {
+  const inputHistory = useInputHistory({
-    handleSubmit: handleHistorySubmit,
-    inputKey,
-    setInputKey,
-  } = useInputHistory({
     userMessages,
     onSubmit: (value) => {
       // Adapt onSubmit to use the lifted setQuery
       handleFinalSubmit(value);
-      setQuery(''); // Clear query from the App's state
+      onChangeAndMoveCursor('');
     },
     isActive: isInputActive && !completion.showSuggestions,
-    query,
+    currentQuery: query,
-    setQuery,
+    onChangeAndMoveCursor,
   });
 
   // --- Render Logic ---
@@ -223,15 +233,17 @@ export const App = ({ config, settings, cliVersion }: AppProps) => {
 
               <InputPrompt
                 query={query}
-                setQuery={setQuery}
+                onChange={setQuery}
-                inputKey={inputKey}
+                onChangeAndMoveCursor={onChangeAndMoveCursor}
-                setInputKey={setInputKey}
+                editorState={editorState}
-                onSubmit={handleHistorySubmit}
+                onSubmit={inputHistory.handleSubmit}
                 showSuggestions={completion.showSuggestions}
                 suggestions={completion.suggestions}
                 activeSuggestionIndex={completion.activeSuggestionIndex}
-                navigateUp={completion.navigateUp}
+                navigateHistoryUp={inputHistory.navigateUp}
-                navigateDown={completion.navigateDown}
+                navigateHistoryDown={inputHistory.navigateDown}
+                navigateSuggestionUp={completion.navigateUp}
+                navigateSuggestionDown={completion.navigateDown}
                 resetCompletion={completion.resetCompletionState}
               />
               {completion.showSuggestions && (

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

@@ -5,40 +5,47 @@
  */
 
 import React, { useCallback } from 'react';
-import { Text, Box, useInput, useFocus, Key } from 'ink';
+import { Text, Box, Key } from 'ink';
-import TextInput from 'ink-text-input';
 import { Colors } from '../colors.js';
 import { Suggestion } from './SuggestionsDisplay.js';
+import { MultilineTextEditor } from './shared/multiline-editor.js';
 
 interface InputPromptProps {
   query: string;
-  setQuery: React.Dispatch<React.SetStateAction<string>>;
+  onChange: (value: string) => void;
-  inputKey: number;
+  onChangeAndMoveCursor: (value: string) => void;
-  setInputKey: React.Dispatch<React.SetStateAction<number>>;
+  editorState: EditorState;
   onSubmit: (value: string) => void;
   showSuggestions: boolean;
   suggestions: Suggestion[];
   activeSuggestionIndex: number;
-  navigateUp: () => void;
-  navigateDown: () => void;
   resetCompletion: () => void;
+  navigateHistoryUp: () => void;
+  navigateHistoryDown: () => void;
+  navigateSuggestionUp: () => void;
+  navigateSuggestionDown: () => void;
+}
+
+export interface EditorState {
+  key: number;
+  initialCursorOffset?: number;
 }
 
 export const InputPrompt: React.FC<InputPromptProps> = ({
   query,
-  setQuery,
+  onChange,
-  inputKey,
+  onChangeAndMoveCursor,
-  setInputKey,
+  editorState,
   onSubmit,
   showSuggestions,
   suggestions,
   activeSuggestionIndex,
-  navigateUp,
+  navigateHistoryUp,
-  navigateDown,
+  navigateHistoryDown,
+  navigateSuggestionUp,
+  navigateSuggestionDown,
   resetCompletion,
 }) => {
-  const { isFocused } = useFocus({ autoFocus: true });
-
   const handleAutocomplete = useCallback(
     (indexToUse: number) => {
       if (indexToUse < 0 || indexToUse >= suggestions.length) {
@@ -52,7 +59,7 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
         const slashIndex = query.indexOf('/');
         const base = query.substring(0, slashIndex + 1);
         const newValue = base + selectedSuggestion.value;
-        setQuery(newValue);
+        onChangeAndMoveCursor(newValue);
       } else {
         // Handle @ command completion
         const atIndex = query.lastIndexOf('@');
@@ -73,32 +80,30 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
         }
 
         const newValue = base + selectedSuggestion.value;
-        setQuery(newValue);
+        onChangeAndMoveCursor(newValue);
       }
 
       resetCompletion(); // Hide suggestions after selection
-      setInputKey((k) => k + 1); // Increment key to force re-render and cursor reset
     },
-    [query, setQuery, suggestions, resetCompletion, setInputKey],
+    [query, suggestions, resetCompletion, onChangeAndMoveCursor],
   );
 
-  useInput(
+  const inputPreprocessor = useCallback(
     (input: string, key: Key) => {
-      if (!isFocused) {
-        return;
-      }
-
       if (showSuggestions) {
         if (key.upArrow) {
-          navigateUp();
+          navigateSuggestionUp();
+          return true;
         } else if (key.downArrow) {
-          navigateDown();
+          navigateSuggestionDown();
+          return true;
         } else if (key.tab) {
           if (suggestions.length > 0) {
             const targetIndex =
               activeSuggestionIndex === -1 ? 0 : activeSuggestionIndex;
             if (targetIndex < suggestions.length) {
               handleAutocomplete(targetIndex);
+              return true;
             }
           }
         } else if (key.return) {
@@ -109,34 +114,51 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
               onSubmit(query);
             }
           }
+          return true;
         } else if (key.escape) {
           resetCompletion();
+          return true;
         }
       }
-      // Enter key when suggestions are NOT showing is handled by TextInput's onSubmit prop below
+      return false;
     },
-    { isActive: true },
+    [
+      handleAutocomplete,
+      navigateSuggestionDown,
+      navigateSuggestionUp,
+      query,
+      suggestions,
+      showSuggestions,
+      resetCompletion,
+      activeSuggestionIndex,
+      onSubmit,
+    ],
   );
 
   return (
     <Box borderStyle="round" borderColor={Colors.AccentBlue} paddingX={1}>
       <Text color={Colors.AccentPurple}>&gt; </Text>
       <Box flexGrow={1}>
-        <TextInput
+        <MultilineTextEditor
-          key={inputKey.toString()}
+          key={editorState.key.toString()}
-          value={query}
+          initialCursorOffset={editorState.initialCursorOffset}
-          onChange={setQuery}
+          initialText={query}
+          onChange={onChange}
           placeholder="Enter your message or use tools (e.g., @src/file.txt)..."
+          /* Account for width used by the box and &gt; */
+          navigateUp={navigateHistoryUp}
+          navigateDown={navigateHistoryDown}
+          inputPreprocessor={inputPreprocessor}
+          widthUsedByParent={3}
+          widthFraction={0.9}
           onSubmit={() => {
             // This onSubmit is for the TextInput component itself.
             // It should only fire if suggestions are NOT showing,
-            // as useInput handles Enter when suggestions are visible.
+            // as inputPreprocessor handles Enter when suggestions are visible.
             const trimmedQuery = query.trim();
             if (!showSuggestions && trimmedQuery) {
               onSubmit(trimmedQuery);
             }
-            // If suggestions ARE showing, useInput's Enter handler
-            // would have already dealt with it (either completing or submitting).
           }}
         />
       </Box>

packages/cli/src/ui/components/shared/multiline-editor.tsx

@@ -0,0 +1,276 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { TextBuffer } from './text-buffer.js';
+import chalk from 'chalk';
+import { Box, Text, useInput, useStdin, Key } from 'ink';
+import React, { useState, useCallback } from 'react';
+import { useTerminalSize } from '../../hooks/useTerminalSize.js';
+import { Colors } from '../../colors.js';
+
+export interface MultilineTextEditorProps {
+  // Initial contents.
+  readonly initialText?: string;
+
+  // Placeholder text.
+  readonly placeholder?: string;
+
+  // Visible width.
+  readonly width?: number;
+
+  // Visible height.
+  readonly height?: number;
+
+  // Called when the user submits (plain <Enter> key).
+  readonly onSubmit?: (text: string) => void;
+
+  // Capture keyboard input.
+  readonly focus?: boolean;
+
+  // Called when the internal text buffer updates.
+  readonly onChange?: (text: string) => void;
+
+  // Called when the user attempts to navigate past the start of the editor
+  // with the up arrow.
+  readonly navigateUp?: () => void;
+
+  // Called when the user attempts to navigate past the end of the editor
+  // with the down arrow.
+  readonly navigateDown?: () => void;
+
+  // Called on all key events to allow the caller. Returns true if the
+  // event was handled and should not be passed to the editor.
+  readonly inputPreprocessor?: (input: string, key: Key) => boolean;
+
+  // Optional initial cursor position (character offset)
+  readonly initialCursorOffset?: number;
+
+  readonly widthUsedByParent: number;
+
+  readonly widthFraction?: number;
+}
+
+export const MultilineTextEditor = ({
+  initialText = '',
+  placeholder = '',
+  width,
+  height = 10,
+  onSubmit,
+  focus = true,
+  onChange,
+  initialCursorOffset,
+  widthUsedByParent,
+  widthFraction = 1,
+  navigateUp,
+  navigateDown,
+  inputPreprocessor,
+}: MultilineTextEditorProps): React.ReactElement => {
+  const [buffer, setBuffer] = useState(
+    () => new TextBuffer(initialText, initialCursorOffset),
+  );
+
+  const terminalSize = useTerminalSize();
+  const effectiveWidth = Math.max(
+    20,
+    width ??
+      Math.round(terminalSize.columns * widthFraction) - widthUsedByParent,
+  );
+
+  const { stdin, setRawMode } = useStdin();
+
+  // TODO(jacobr): make TextBuffer immutable rather than this hack to act
+  // like it is immutable.
+  const updateBufferState = useCallback(
+    (mutator: (currentBuffer: TextBuffer) => void) => {
+      setBuffer((currentBuffer) => {
+        mutator(currentBuffer);
+        // Create a new instance from the mutated buffer to trigger re-render
+        return TextBuffer.fromBuffer(currentBuffer);
+      });
+    },
+    [],
+  );
+
+  const openExternalEditor = useCallback(async () => {
+    const wasRaw = stdin?.isRaw ?? false;
+    try {
+      setRawMode?.(false);
+      // openInExternalEditor mutates the buffer instance
+      await buffer.openInExternalEditor();
+    } catch (err) {
+      console.error('[MultilineTextEditor] external editor error', err);
+    } finally {
+      if (wasRaw) {
+        setRawMode?.(true);
+      }
+      // Update state with the mutated buffer to trigger re-render
+      setBuffer(TextBuffer.fromBuffer(buffer));
+    }
+  }, [buffer, stdin, setRawMode, setBuffer]);
+
+  useInput(
+    (input, key) => {
+      if (!focus) {
+        return;
+      }
+
+      if (inputPreprocessor?.(input, key) === true) {
+        return;
+      }
+
+      const isCtrlX =
+        (key.ctrl && (input === 'x' || input === '\x18')) || input === '\x18';
+      const isCtrlE =
+        (key.ctrl && (input === 'e' || input === '\x05')) ||
+        input === '\x05' ||
+        (!key.ctrl &&
+          input === 'e' &&
+          input.length === 1 &&
+          input.charCodeAt(0) === 5);
+      if (isCtrlX || isCtrlE) {
+        openExternalEditor();
+        return;
+      }
+
+      if (
+        process.env['TEXTBUFFER_DEBUG'] === '1' ||
+        process.env['TEXTBUFFER_DEBUG'] === 'true'
+      ) {
+        console.log('[MultilineTextEditor] event', { input, key });
+      }
+
+      let bufferMutated = false;
+
+      if (input.startsWith('[') && input.endsWith('u')) {
+        const m = input.match(/^\[([0-9]+);([0-9]+)u$/);
+        if (m && m[1] === '13') {
+          const mod = Number(m[2]);
+          const hasCtrl = Math.floor(mod / 4) % 2 === 1;
+          if (hasCtrl) {
+            if (onSubmit) {
+              onSubmit(buffer.getText());
+            }
+          } else {
+            buffer.newline();
+            bufferMutated = true;
+          }
+          if (bufferMutated) {
+            updateBufferState((_) => {}); // Trigger re-render if mutated
+          }
+          return;
+        }
+      }
+
+      if (input.startsWith('[27;') && input.endsWith('~')) {
+        const m = input.match(/^\[27;([0-9]+);13~$/);
+        if (m) {
+          const mod = Number(m[1]);
+          const hasCtrl = Math.floor(mod / 4) % 2 === 1;
+          if (hasCtrl) {
+            if (onSubmit) {
+              onSubmit(buffer.getText());
+            }
+          } else {
+            buffer.newline();
+            bufferMutated = true;
+          }
+          if (bufferMutated) {
+            updateBufferState((_) => {}); // Trigger re-render if mutated
+          }
+          return;
+        }
+      }
+
+      if (input === '\n') {
+        buffer.newline();
+        updateBufferState((_) => {});
+        return;
+      }
+
+      if (input === '\r') {
+        if (onSubmit) {
+          onSubmit(buffer.getText());
+        }
+        return;
+      }
+
+      if (key.upArrow) {
+        if (buffer.getCursor()[0] === 0 && navigateUp) {
+          navigateUp();
+          return;
+        }
+      }
+
+      if (key.downArrow) {
+        if (
+          buffer.getCursor()[0] === buffer.getText().split('\n').length - 1 &&
+          navigateDown
+        ) {
+          navigateDown();
+          return;
+        }
+      }
+
+      const modifiedByHandleInput = buffer.handleInput(
+        input,
+        key as Record<string, boolean>,
+        { height, width: effectiveWidth },
+      );
+
+      if (modifiedByHandleInput) {
+        updateBufferState((_) => {});
+      }
+
+      const newText = buffer.getText();
+      if (onChange) {
+        onChange(newText);
+      }
+    },
+    { isActive: focus },
+  );
+
+  const visibleLines = buffer.getVisibleLines({
+    height,
+    width: effectiveWidth,
+  });
+  const [cursorRow, cursorCol] = buffer.getCursor();
+  const scrollRow = buffer.getScrollRow();
+  const scrollCol = buffer.getScrollCol();
+
+  return (
+    <Box flexDirection="column">
+      {buffer.getText().length === 0 && placeholder ? (
+        <Text color={Colors.SubtleComment}>{placeholder}</Text>
+      ) : (
+        visibleLines.map((lineText, idx) => {
+          const absoluteRow = scrollRow + idx;
+          let display = lineText.slice(scrollCol, scrollCol + effectiveWidth);
+          if (display.length < effectiveWidth) {
+            display = display.padEnd(effectiveWidth, ' ');
+          }
+
+          if (absoluteRow === cursorRow) {
+            const relativeCol = cursorCol - scrollCol;
+            const highlightCol = relativeCol;
+
+            if (highlightCol >= 0 && highlightCol < effectiveWidth) {
+              const charToHighlight = display[highlightCol] || ' ';
+              const highlighted = chalk.inverse(charToHighlight);
+              display =
+                display.slice(0, highlightCol) +
+                highlighted +
+                display.slice(highlightCol + 1);
+            } else if (relativeCol === effectiveWidth) {
+              display =
+                display.slice(0, effectiveWidth - 1) + chalk.inverse(' ');
+            }
+          }
+          return <Text key={idx}>{display}</Text>;
+        })
+      )}
+    </Box>
+  );
+};

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

@@ -4,36 +4,32 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { useCallback, useState } from 'react';
+import { useState, useCallback } from 'react';
-import { useInput } from 'ink';
 
 interface UseInputHistoryProps {
   userMessages: readonly string[];
   onSubmit: (value: string) => void;
   isActive: boolean;
-  query: string;
+  currentQuery: string; // Renamed from query to avoid confusion
-  setQuery: React.Dispatch<React.SetStateAction<string>>;
+  onChangeAndMoveCursor: (value: string) => void;
 }
 
 interface UseInputHistoryReturn {
-  query: string;
-  setQuery: React.Dispatch<React.SetStateAction<string>>;
   handleSubmit: (value: string) => void;
-  inputKey: number;
+  navigateUp: () => boolean;
-  setInputKey: React.Dispatch<React.SetStateAction<number>>;
+  navigateDown: () => boolean;
 }
 
 export function useInputHistory({
   userMessages,
   onSubmit,
   isActive,
-  query,
+  currentQuery,
-  setQuery,
+  onChangeAndMoveCursor: setQueryAndMoveCursor,
 }: UseInputHistoryProps): UseInputHistoryReturn {
   const [historyIndex, setHistoryIndex] = useState<number>(-1);
   const [originalQueryBeforeNav, setOriginalQueryBeforeNav] =
     useState<string>('');
-  const [inputKey, setInputKey] = useState<number>(0);
 
   const resetHistoryNav = useCallback(() => {
     setHistoryIndex(-1);
@@ -44,71 +40,72 @@ export function useInputHistory({
     (value: string) => {
       const trimmedValue = value.trim();
       if (trimmedValue) {
-        onSubmit(trimmedValue); // This will call handleFinalSubmit, which then calls setQuery('') from App.tsx
+        onSubmit(trimmedValue); // Parent handles clearing the query
       }
       resetHistoryNav();
     },
     [onSubmit, resetHistoryNav],
   );
 
-  useInput(
+  const navigateUp = useCallback(() => {
-    (input, key) => {
+    if (!isActive) return false;
-      if (!isActive) {
+    if (userMessages.length === 0) return false;
-        return;
-      }
 
-      let didNavigate = false;
+    let nextIndex = historyIndex;
+    if (historyIndex === -1) {
+      // Store the current query from the parent before navigating
+      setOriginalQueryBeforeNav(currentQuery);
+      nextIndex = 0;
+    } else if (historyIndex < userMessages.length - 1) {
+      nextIndex = historyIndex + 1;
+    } else {
+      return false; // Already at the oldest message
+    }
 
-      if (key.upArrow) {
+    if (nextIndex !== historyIndex) {
-        if (userMessages.length === 0) return;
+      setHistoryIndex(nextIndex);
+      const newValue = userMessages[userMessages.length - 1 - nextIndex];
+      setQueryAndMoveCursor(newValue); // Call the prop passed from parent
+      return true;
+    }
+    return false;
+  }, [
+    historyIndex,
+    setHistoryIndex,
+    setQueryAndMoveCursor,
+    userMessages,
+    isActive,
+    currentQuery, // Use currentQuery from props
+    setOriginalQueryBeforeNav,
+  ]);
 
-        let nextIndex = historyIndex;
+  const navigateDown = useCallback(() => {
-        if (historyIndex === -1) {
+    if (!isActive) return false;
-          setOriginalQueryBeforeNav(query);
+    if (historyIndex === -1) return false; // Not currently navigating history
-          nextIndex = 0;
-        } else if (historyIndex < userMessages.length - 1) {
-          nextIndex = historyIndex + 1;
-        } else {
-          return;
-        }
 
-        if (nextIndex !== historyIndex) {
+    const nextIndex = historyIndex - 1;
-          setHistoryIndex(nextIndex);
+    setHistoryIndex(nextIndex);
-          const newValue = userMessages[userMessages.length - 1 - nextIndex];
-          setQuery(newValue);
-          setInputKey((k) => k + 1);
-          didNavigate = true;
-        }
-      } else if (key.downArrow) {
-        if (historyIndex === -1) return;
 
-        const nextIndex = historyIndex - 1;
+    if (nextIndex === -1) {
-        setHistoryIndex(nextIndex);
+      // Reached the end of history navigation, restore original query
-
+      setQueryAndMoveCursor(originalQueryBeforeNav);
-        if (nextIndex === -1) {
+    } else {
-          setQuery(originalQueryBeforeNav);
+      const newValue = userMessages[userMessages.length - 1 - nextIndex];
-        } else {
+      setQueryAndMoveCursor(newValue);
-          const newValue = userMessages[userMessages.length - 1 - nextIndex];
+    }
-          setQuery(newValue);
+    return true;
-        }
+  }, [
-        setInputKey((k) => k + 1);
+    historyIndex,
-        didNavigate = true;
+    setHistoryIndex,
-      } else {
+    originalQueryBeforeNav,
-        if (historyIndex !== -1 && !didNavigate) {
+    setQueryAndMoveCursor,
-          if (input || key.backspace || key.delete) {
+    userMessages,
-            resetHistoryNav();
+    isActive,
-          }
+  ]);
-        }
-      }
-    },
-    { isActive },
-  );
 
   return {
-    query,
-    setQuery,
     handleSubmit,
-    inputKey,
+    navigateUp,
-    setInputKey,
+    navigateDown,
   };
 }

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

@@ -0,0 +1,32 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { useEffect, useState } from 'react';
+
+const TERMINAL_PADDING_X = 8;
+
+export function useTerminalSize(): { columns: number; rows: number } {
+  const [size, setSize] = useState({
+    columns: (process.stdout.columns || 60) - TERMINAL_PADDING_X,
+    rows: process.stdout.rows || 20,
+  });
+
+  useEffect(() => {
+    function updateSize() {
+      setSize({
+        columns: (process.stdout.columns || 60) - TERMINAL_PADDING_X,
+        rows: process.stdout.rows || 20,
+      });
+    }
+
+    process.stdout.on('resize', updateSize);
+    return () => {
+      process.stdout.off('resize', updateSize);
+    };
+  }, []);
+
+  return size;
+}