feat(cli): prompt completion (#4691)

Co-authored-by: Jacob Richman <[email protected]>

11 files changed, 540 insertions, 43 deletions

diff --git a/packages/cli/src/config/config.ts b/packages/cli/src/config/config.ts
index 9731b503..0b21ff2e 100644
--- a/packages/cli/src/config/config.ts
+++ b/packages/cli/src/config/config.ts
@@ -542,6 +542,7 @@ export async function loadCliConfig(
     trustedFolder,
     shouldUseNodePtyShell: settings.shouldUseNodePtyShell,
     skipNextSpeakerCheck: settings.skipNextSpeakerCheck,
+    enablePromptCompletion: settings.enablePromptCompletion ?? false,
   });
 }
 
diff --git a/packages/cli/src/config/settingsSchema.ts b/packages/cli/src/config/settingsSchema.ts
index 6d9e1f1e..7f28b698 100644
--- a/packages/cli/src/config/settingsSchema.ts
+++ b/packages/cli/src/config/settingsSchema.ts
@@ -524,6 +524,16 @@ export const SETTINGS_SCHEMA = {
     description: 'Skip the next speaker check.',
     showInDialog: true,
   },
+  enablePromptCompletion: {
+    type: 'boolean',
+    label: 'Enable Prompt Completion',
+    category: 'General',
+    requiresRestart: true,
+    default: false,
+    description:
+      'Enable AI-powered prompt completion suggestions while typing.',
+    showInDialog: true,
+  },
 } as const;
 
 type InferSettings<T extends SettingsSchema> = {
diff --git a/packages/cli/src/ui/App.test.tsx b/packages/cli/src/ui/App.test.tsx
index f78ec580..9f8a681f 100644
--- a/packages/cli/src/ui/App.test.tsx
+++ b/packages/cli/src/ui/App.test.tsx
@@ -147,6 +147,7 @@ vi.mock('@google/gemini-cli-core', async (importOriginal) => {
         getShowMemoryUsage: vi.fn(() => opts.showMemoryUsage ?? false),
         getAccessibility: vi.fn(() => opts.accessibility ?? {}),
         getProjectRoot: vi.fn(() => opts.targetDir),
+        getEnablePromptCompletion: vi.fn(() => false),
         getGeminiClient: vi.fn(() => ({
           getUserTier: vi.fn(),
         })),
diff --git a/packages/cli/src/ui/components/InputPrompt.test.tsx b/packages/cli/src/ui/components/InputPrompt.test.tsx
index 11a0eb48..a3346490 100644
--- a/packages/cli/src/ui/components/InputPrompt.test.tsx
+++ b/packages/cli/src/ui/components/InputPrompt.test.tsx
@@ -160,6 +160,11 @@ describe('InputPrompt', () => {
       setActiveSuggestionIndex: vi.fn(),
       setShowSuggestions: vi.fn(),
       handleAutocomplete: vi.fn(),
+      promptCompletion: {
+        text: '',
+        accept: vi.fn(),
+        clear: vi.fn(),
+      },
     };
     mockedUseCommandCompletion.mockReturnValue(mockCommandCompletion);
 
diff --git a/packages/cli/src/ui/components/InputPrompt.tsx b/packages/cli/src/ui/components/InputPrompt.tsx
index 02c25bd8..01666c66 100644
--- a/packages/cli/src/ui/components/InputPrompt.tsx
+++ b/packages/cli/src/ui/components/InputPrompt.tsx
@@ -10,7 +10,7 @@ import { theme } from '../semantic-colors.js';
 import { SuggestionsDisplay } from './SuggestionsDisplay.js';
 import { useInputHistory } from '../hooks/useInputHistory.js';
 import { TextBuffer, logicalPosToOffset } from './shared/text-buffer.js';
-import { cpSlice, cpLen } from '../utils/textUtils.js';
+import { cpSlice, cpLen, toCodePoints } from '../utils/textUtils.js';
 import chalk from 'chalk';
 import stringWidth from 'string-width';
 import { useShellHistory } from '../hooks/useShellHistory.js';
@@ -403,6 +403,16 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
         }
       }
 
+      // Handle Tab key for ghost text acceptance
+      if (
+        key.name === 'tab' &&
+        !completion.showSuggestions &&
+        completion.promptCompletion.text
+      ) {
+        completion.promptCompletion.accept();
+        return;
+      }
+
       if (!shellModeActive) {
         if (keyMatchers[Command.HISTORY_UP](key)) {
           inputHistory.navigateUp();
@@ -507,6 +517,17 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
 
       // Fall back to the text buffer's default input handling for all other keys
       buffer.handleInput(key);
+
+      // Clear ghost text when user types regular characters (not navigation/control keys)
+      if (
+        completion.promptCompletion.text &&
+        key.sequence &&
+        key.sequence.length === 1 &&
+        !key.ctrl &&
+        !key.meta
+      ) {
+        completion.promptCompletion.clear();
+      }
     },
     [
       focus,
@@ -540,6 +561,119 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
     buffer.visualCursor;
   const scrollVisualRow = buffer.visualScrollRow;
 
+  const getGhostTextLines = useCallback(() => {
+    if (
+      !completion.promptCompletion.text ||
+      !buffer.text ||
+      !completion.promptCompletion.text.startsWith(buffer.text)
+    ) {
+      return { inlineGhost: '', additionalLines: [] };
+    }
+
+    const ghostSuffix = completion.promptCompletion.text.slice(
+      buffer.text.length,
+    );
+    if (!ghostSuffix) {
+      return { inlineGhost: '', additionalLines: [] };
+    }
+
+    const currentLogicalLine = buffer.lines[buffer.cursor[0]] || '';
+    const cursorCol = buffer.cursor[1];
+
+    const textBeforeCursor = cpSlice(currentLogicalLine, 0, cursorCol);
+    const usedWidth = stringWidth(textBeforeCursor);
+    const remainingWidth = Math.max(0, inputWidth - usedWidth);
+
+    const ghostTextLinesRaw = ghostSuffix.split('\n');
+    const firstLineRaw = ghostTextLinesRaw.shift() || '';
+
+    let inlineGhost = '';
+    let remainingFirstLine = '';
+
+    if (stringWidth(firstLineRaw) <= remainingWidth) {
+      inlineGhost = firstLineRaw;
+    } else {
+      const words = firstLineRaw.split(' ');
+      let currentLine = '';
+      let wordIdx = 0;
+      for (const word of words) {
+        const prospectiveLine = currentLine ? `${currentLine} ${word}` : word;
+        if (stringWidth(prospectiveLine) > remainingWidth) {
+          break;
+        }
+        currentLine = prospectiveLine;
+        wordIdx++;
+      }
+      inlineGhost = currentLine;
+      if (words.length > wordIdx) {
+        remainingFirstLine = words.slice(wordIdx).join(' ');
+      }
+    }
+
+    const linesToWrap = [];
+    if (remainingFirstLine) {
+      linesToWrap.push(remainingFirstLine);
+    }
+    linesToWrap.push(...ghostTextLinesRaw);
+    const remainingGhostText = linesToWrap.join('\n');
+
+    const additionalLines: string[] = [];
+    if (remainingGhostText) {
+      const textLines = remainingGhostText.split('\n');
+      for (const textLine of textLines) {
+        const words = textLine.split(' ');
+        let currentLine = '';
+
+        for (const word of words) {
+          const prospectiveLine = currentLine ? `${currentLine} ${word}` : word;
+          const prospectiveWidth = stringWidth(prospectiveLine);
+
+          if (prospectiveWidth > inputWidth) {
+            if (currentLine) {
+              additionalLines.push(currentLine);
+            }
+
+            let wordToProcess = word;
+            while (stringWidth(wordToProcess) > inputWidth) {
+              let part = '';
+              const wordCP = toCodePoints(wordToProcess);
+              let partWidth = 0;
+              let splitIndex = 0;
+              for (let i = 0; i < wordCP.length; i++) {
+                const char = wordCP[i];
+                const charWidth = stringWidth(char);
+                if (partWidth + charWidth > inputWidth) {
+                  break;
+                }
+                part += char;
+                partWidth += charWidth;
+                splitIndex = i + 1;
+              }
+              additionalLines.push(part);
+              wordToProcess = cpSlice(wordToProcess, splitIndex);
+            }
+            currentLine = wordToProcess;
+          } else {
+            currentLine = prospectiveLine;
+          }
+        }
+        if (currentLine) {
+          additionalLines.push(currentLine);
+        }
+      }
+    }
+
+    return { inlineGhost, additionalLines };
+  }, [
+    completion.promptCompletion.text,
+    buffer.text,
+    buffer.lines,
+    buffer.cursor,
+    inputWidth,
+  ]);
+
+  const { inlineGhost, additionalLines } = getGhostTextLines();
+
   return (
     <>
       <Box
@@ -573,42 +707,91 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
               <Text color={theme.text.secondary}>{placeholder}</Text>
             )
           ) : (
-            linesToRender.map((lineText, visualIdxInRenderedSet) => {
-              const cursorVisualRow = cursorVisualRowAbsolute - scrollVisualRow;
-              let display = cpSlice(lineText, 0, inputWidth);
-              const currentVisualWidth = stringWidth(display);
-              if (currentVisualWidth < inputWidth) {
-                display = display + ' '.repeat(inputWidth - currentVisualWidth);
-              }
+            linesToRender
+              .map((lineText, visualIdxInRenderedSet) => {
+                const cursorVisualRow =
+                  cursorVisualRowAbsolute - scrollVisualRow;
+                let display = cpSlice(lineText, 0, inputWidth);
 
-              if (focus && visualIdxInRenderedSet === cursorVisualRow) {
-                const relativeVisualColForHighlight = cursorVisualColAbsolute;
+                const isOnCursorLine =
+                  focus && visualIdxInRenderedSet === cursorVisualRow;
+                const currentLineGhost = isOnCursorLine ? inlineGhost : '';
 
-                if (relativeVisualColForHighlight >= 0) {
-                  if (relativeVisualColForHighlight < cpLen(display)) {
-                    const charToHighlight =
-                      cpSlice(
-                        display,
-                        relativeVisualColForHighlight,
-                        relativeVisualColForHighlight + 1,
-                      ) || ' ';
-                    const highlighted = chalk.inverse(charToHighlight);
-                    display =
-                      cpSlice(display, 0, relativeVisualColForHighlight) +
-                      highlighted +
-                      cpSlice(display, relativeVisualColForHighlight + 1);
-                  } else if (
-                    relativeVisualColForHighlight === cpLen(display) &&
-                    cpLen(display) === inputWidth
-                  ) {
-                    display = display + chalk.inverse(' ');
+                const ghostWidth = stringWidth(currentLineGhost);
+
+                if (focus && visualIdxInRenderedSet === cursorVisualRow) {
+                  const relativeVisualColForHighlight = cursorVisualColAbsolute;
+
+                  if (relativeVisualColForHighlight >= 0) {
+                    if (relativeVisualColForHighlight < cpLen(display)) {
+                      const charToHighlight =
+                        cpSlice(
+                          display,
+                          relativeVisualColForHighlight,
+                          relativeVisualColForHighlight + 1,
+                        ) || ' ';
+                      const highlighted = chalk.inverse(charToHighlight);
+                      display =
+                        cpSlice(display, 0, relativeVisualColForHighlight) +
+                        highlighted +
+                        cpSlice(display, relativeVisualColForHighlight + 1);
+                    } else if (
+                      relativeVisualColForHighlight === cpLen(display)
+                    ) {
+                      if (!currentLineGhost) {
+                        display = display + chalk.inverse(' ');
+                      }
+                    }
                   }
                 }
-              }
-              return (
-                <Text key={`line-${visualIdxInRenderedSet}`}>{display}</Text>
-              );
-            })
+
+                const showCursorBeforeGhost =
+                  focus &&
+                  visualIdxInRenderedSet === cursorVisualRow &&
+                  cursorVisualColAbsolute ===
+                    // eslint-disable-next-line no-control-regex
+                    cpLen(display.replace(/\x1b\[[0-9;]*m/g, '')) &&
+                  currentLineGhost;
+
+                const actualDisplayWidth = stringWidth(display);
+                const cursorWidth = showCursorBeforeGhost ? 1 : 0;
+                const totalContentWidth =
+                  actualDisplayWidth + cursorWidth + ghostWidth;
+                const trailingPadding = Math.max(
+                  0,
+                  inputWidth - totalContentWidth,
+                );
+
+                return (
+                  <Text key={`line-${visualIdxInRenderedSet}`}>
+                    {display}
+                    {showCursorBeforeGhost && chalk.inverse(' ')}
+                    {currentLineGhost && (
+                      <Text color={theme.text.secondary}>
+                        {currentLineGhost}
+                      </Text>
+                    )}
+                    {trailingPadding > 0 && ' '.repeat(trailingPadding)}
+                  </Text>
+                );
+              })
+              .concat(
+                additionalLines.map((ghostLine, index) => {
+                  const padding = Math.max(
+                    0,
+                    inputWidth - stringWidth(ghostLine),
+                  );
+                  return (
+                    <Text
+                      key={`ghost-line-${index}`}
+                      color={theme.text.secondary}
+                    >
+                      {ghostLine}
+                      {' '.repeat(padding)}
+                    </Text>
+                  );
+                }),
+              )
           )}
         </Box>
       </Box>
diff --git a/packages/cli/src/ui/hooks/useCommandCompletion.test.ts b/packages/cli/src/ui/hooks/useCommandCompletion.test.ts
index a3c96935..00bc8ac3 100644
--- a/packages/cli/src/ui/hooks/useCommandCompletion.test.ts
+++ b/packages/cli/src/ui/hooks/useCommandCompletion.test.ts
@@ -84,7 +84,9 @@ const setupMocks = ({
 
 describe('useCommandCompletion', () => {
   const mockCommandContext = {} as CommandContext;
-  const mockConfig = {} as Config;
+  const mockConfig = {
+    getEnablePromptCompletion: () => false,
+  } as Config;
   const testDirs: string[] = [];
   const testRootDir = '/';
 
@@ -511,7 +513,7 @@ describe('useCommandCompletion', () => {
       });
 
       expect(result.current.textBuffer.text).toBe(
-        '@src/file1.txt  is a good file',
+        '@src/file1.txt is a good file',
       );
     });
   });
diff --git a/packages/cli/src/ui/hooks/useCommandCompletion.tsx b/packages/cli/src/ui/hooks/useCommandCompletion.tsx
index 07d0e056..166f03c5 100644
--- a/packages/cli/src/ui/hooks/useCommandCompletion.tsx
+++ b/packages/cli/src/ui/hooks/useCommandCompletion.tsx
@@ -15,6 +15,11 @@ import { isSlashCommand } from '../utils/commandUtils.js';
 import { toCodePoints } from '../utils/textUtils.js';
 import { useAtCompletion } from './useAtCompletion.js';
 import { useSlashCompletion } from './useSlashCompletion.js';
+import {
+  usePromptCompletion,
+  PromptCompletion,
+  PROMPT_COMPLETION_MIN_LENGTH,
+} from './usePromptCompletion.js';
 import { Config } from '@google/gemini-cli-core';
 import { useCompletion } from './useCompletion.js';
 
@@ -22,6 +27,7 @@ export enum CompletionMode {
   IDLE = 'IDLE',
   AT = 'AT',
   SLASH = 'SLASH',
+  PROMPT = 'PROMPT',
 }
 
 export interface UseCommandCompletionReturn {
@@ -37,6 +43,7 @@ export interface UseCommandCompletionReturn {
   navigateUp: () => void;
   navigateDown: () => void;
   handleAutocomplete: (indexToUse: number) => void;
+  promptCompletion: PromptCompletion;
 }
 
 export function useCommandCompletion(
@@ -93,12 +100,7 @@ export function useCommandCompletion(
             backslashCount++;
           }
           if (backslashCount % 2 === 0) {
-            return {
-              completionMode: CompletionMode.IDLE,
-              query: null,
-              completionStart: -1,
-              completionEnd: -1,
-            };
+            break;
           }
         } else if (char === '@') {
           let end = codePoints.length;
@@ -125,13 +127,33 @@ export function useCommandCompletion(
           };
         }
       }
+
+      // Check for prompt completion - only if enabled
+      const trimmedText = buffer.text.trim();
+      const isPromptCompletionEnabled =
+        config?.getEnablePromptCompletion() ?? false;
+
+      if (
+        isPromptCompletionEnabled &&
+        trimmedText.length >= PROMPT_COMPLETION_MIN_LENGTH &&
+        !trimmedText.startsWith('/') &&
+        !trimmedText.includes('@')
+      ) {
+        return {
+          completionMode: CompletionMode.PROMPT,
+          query: trimmedText,
+          completionStart: 0,
+          completionEnd: trimmedText.length,
+        };
+      }
+
       return {
         completionMode: CompletionMode.IDLE,
         query: null,
         completionStart: -1,
         completionEnd: -1,
       };
-    }, [cursorRow, cursorCol, buffer.lines]);
+    }, [cursorRow, cursorCol, buffer.lines, buffer.text, config]);
 
   useAtCompletion({
     enabled: completionMode === CompletionMode.AT,
@@ -152,6 +174,12 @@ export function useCommandCompletion(
     setIsPerfectMatch,
   });
 
+  const promptCompletion = usePromptCompletion({
+    buffer,
+    config,
+    enabled: completionMode === CompletionMode.PROMPT,
+  });
+
   useEffect(() => {
     setActiveSuggestionIndex(suggestions.length > 0 ? 0 : -1);
     setVisibleStartIndex(0);
@@ -202,7 +230,11 @@ export function useCommandCompletion(
         }
       }
 
-      suggestionText += ' ';
+      const lineCodePoints = toCodePoints(buffer.lines[cursorRow] || '');
+      const charAfterCompletion = lineCodePoints[end];
+      if (charAfterCompletion !== ' ') {
+        suggestionText += ' ';
+      }
 
       buffer.replaceRangeByOffset(
         logicalPosToOffset(buffer.lines, cursorRow, start),
@@ -234,5 +266,6 @@ export function useCommandCompletion(
     navigateUp,
     navigateDown,
     handleAutocomplete,
+    promptCompletion,
   };
 }
diff --git a/packages/cli/src/ui/hooks/usePromptCompletion.ts b/packages/cli/src/ui/hooks/usePromptCompletion.ts
new file mode 100644
index 00000000..466d020b
--- /dev/null
+++ b/packages/cli/src/ui/hooks/usePromptCompletion.ts
@@ -0,0 +1,253 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { useState, useCallback, useRef, useEffect, useMemo } from 'react';
+import {
+  Config,
+  DEFAULT_GEMINI_FLASH_LITE_MODEL,
+  getResponseText,
+} from '@google/gemini-cli-core';
+import { Content, GenerateContentConfig } from '@google/genai';
+import { TextBuffer } from '../components/shared/text-buffer.js';
+
+export const PROMPT_COMPLETION_MIN_LENGTH = 5;
+export const PROMPT_COMPLETION_DEBOUNCE_MS = 250;
+
+export interface PromptCompletion {
+  text: string;
+  isLoading: boolean;
+  isActive: boolean;
+  accept: () => void;
+  clear: () => void;
+  markSelected: (selectedText: string) => void;
+}
+
+export interface UsePromptCompletionOptions {
+  buffer: TextBuffer;
+  config?: Config;
+  enabled: boolean;
+}
+
+export function usePromptCompletion({
+  buffer,
+  config,
+  enabled,
+}: UsePromptCompletionOptions): PromptCompletion {
+  const [ghostText, setGhostText] = useState<string>('');
+  const [isLoadingGhostText, setIsLoadingGhostText] = useState<boolean>(false);
+  const abortControllerRef = useRef<AbortController | null>(null);
+  const [justSelectedSuggestion, setJustSelectedSuggestion] =
+    useState<boolean>(false);
+  const lastSelectedTextRef = useRef<string>('');
+  const lastRequestedTextRef = useRef<string>('');
+
+  const isPromptCompletionEnabled =
+    enabled && (config?.getEnablePromptCompletion() ?? false);
+
+  const clearGhostText = useCallback(() => {
+    setGhostText('');
+    setIsLoadingGhostText(false);
+  }, []);
+
+  const acceptGhostText = useCallback(() => {
+    if (ghostText && ghostText.length > buffer.text.length) {
+      buffer.setText(ghostText);
+      setGhostText('');
+      setJustSelectedSuggestion(true);
+      lastSelectedTextRef.current = ghostText;
+    }
+  }, [ghostText, buffer]);
+
+  const markSuggestionSelected = useCallback((selectedText: string) => {
+    setJustSelectedSuggestion(true);
+    lastSelectedTextRef.current = selectedText;
+  }, []);
+
+  const generatePromptSuggestions = useCallback(async () => {
+    const trimmedText = buffer.text.trim();
+    const geminiClient = config?.getGeminiClient();
+
+    if (trimmedText === lastRequestedTextRef.current) {
+      return;
+    }
+
+    if (abortControllerRef.current) {
+      abortControllerRef.current.abort();
+    }
+
+    if (
+      trimmedText.length < PROMPT_COMPLETION_MIN_LENGTH ||
+      !geminiClient ||
+      trimmedText.startsWith('/') ||
+      trimmedText.includes('@') ||
+      !isPromptCompletionEnabled
+    ) {
+      clearGhostText();
+      lastRequestedTextRef.current = '';
+      return;
+    }
+
+    lastRequestedTextRef.current = trimmedText;
+    setIsLoadingGhostText(true);
+
+    abortControllerRef.current = new AbortController();
+    const signal = abortControllerRef.current.signal;
+
+    try {
+      const contents: Content[] = [
+        {
+          role: 'user',
+          parts: [
+            {
+              text: `You are a professional prompt engineering assistant. Complete the user's partial prompt with expert precision and clarity. User's input: "${trimmedText}" Continue this prompt by adding specific, actionable details that align with the user's intent. Focus on: clear, precise language; structured requirements; professional terminology; measurable outcomes. Length Guidelines: Keep suggestions concise (ideally 10-20 characters); prioritize brevity while maintaining clarity; use essential keywords only; avoid redundant phrases. Start your response with the exact user text ("${trimmedText}") followed by your completion. Provide practical, implementation-focused suggestions rather than creative interpretations. Format: Plain text only. Single completion. Match the user's language. Emphasize conciseness over elaboration.`,
+            },
+          ],
+        },
+      ];
+
+      const generationConfig: GenerateContentConfig = {
+        temperature: 0.3,
+        maxOutputTokens: 16000,
+        thinkingConfig: {
+          thinkingBudget: 0,
+        },
+      };
+
+      const response = await geminiClient.generateContent(
+        contents,
+        generationConfig,
+        signal,
+        DEFAULT_GEMINI_FLASH_LITE_MODEL,
+      );
+
+      if (signal.aborted) {
+        return;
+      }
+
+      if (response) {
+        const responseText = getResponseText(response);
+
+        if (responseText) {
+          const suggestionText = responseText.trim();
+
+          if (
+            suggestionText.length > 0 &&
+            suggestionText.startsWith(trimmedText)
+          ) {
+            setGhostText(suggestionText);
+          } else {
+            clearGhostText();
+          }
+        }
+      }
+    } catch (error) {
+      if (
+        !(
+          signal.aborted ||
+          (error instanceof Error && error.name === 'AbortError')
+        )
+      ) {
+        console.error('prompt completion error:', error);
+        // Clear the last requested text to allow retry only on real errors
+        lastRequestedTextRef.current = '';
+      }
+      clearGhostText();
+    } finally {
+      if (!signal.aborted) {
+        setIsLoadingGhostText(false);
+      }
+    }
+  }, [buffer.text, config, clearGhostText, isPromptCompletionEnabled]);
+
+  const isCursorAtEnd = useCallback(() => {
+    const [cursorRow, cursorCol] = buffer.cursor;
+    const totalLines = buffer.lines.length;
+    if (cursorRow !== totalLines - 1) {
+      return false;
+    }
+
+    const lastLine = buffer.lines[cursorRow] || '';
+    return cursorCol === lastLine.length;
+  }, [buffer.cursor, buffer.lines]);
+
+  const handlePromptCompletion = useCallback(() => {
+    if (!isCursorAtEnd()) {
+      clearGhostText();
+      return;
+    }
+
+    const trimmedText = buffer.text.trim();
+
+    if (justSelectedSuggestion && trimmedText === lastSelectedTextRef.current) {
+      return;
+    }
+
+    if (trimmedText !== lastSelectedTextRef.current) {
+      setJustSelectedSuggestion(false);
+      lastSelectedTextRef.current = '';
+    }
+
+    generatePromptSuggestions();
+  }, [
+    buffer.text,
+    generatePromptSuggestions,
+    justSelectedSuggestion,
+    isCursorAtEnd,
+    clearGhostText,
+  ]);
+
+  // Debounce prompt completion
+  useEffect(() => {
+    const timeoutId = setTimeout(
+      handlePromptCompletion,
+      PROMPT_COMPLETION_DEBOUNCE_MS,
+    );
+    return () => clearTimeout(timeoutId);
+  }, [buffer.text, buffer.cursor, handlePromptCompletion]);
+
+  // Ghost text validation - clear if it doesn't match current text or cursor not at end
+  useEffect(() => {
+    const currentText = buffer.text.trim();
+
+    if (ghostText && !isCursorAtEnd()) {
+      clearGhostText();
+      return;
+    }
+
+    if (
+      ghostText &&
+      currentText.length > 0 &&
+      !ghostText.startsWith(currentText)
+    ) {
+      clearGhostText();
+    }
+  }, [buffer.text, buffer.cursor, ghostText, clearGhostText, isCursorAtEnd]);
+
+  // Cleanup on unmount
+  useEffect(() => () => abortControllerRef.current?.abort(), []);
+
+  const isActive = useMemo(() => {
+    if (!isPromptCompletionEnabled) return false;
+
+    if (!isCursorAtEnd()) return false;
+
+    const trimmedText = buffer.text.trim();
+    return (
+      trimmedText.length >= PROMPT_COMPLETION_MIN_LENGTH &&
+      !trimmedText.startsWith('/') &&
+      !trimmedText.includes('@')
+    );
+  }, [buffer.text, isPromptCompletionEnabled, isCursorAtEnd]);
+
+  return {
+    text: ghostText,
+    isLoading: isLoadingGhostText,
+    isActive,
+    accept: acceptGhostText,
+    clear: clearGhostText,
+    markSelected: markSuggestionSelected,
+  };
+}
diff --git a/packages/core/index.ts b/packages/core/index.ts
index 7b75b365..660306ed 100644
--- a/packages/core/index.ts
+++ b/packages/core/index.ts
@@ -8,6 +8,7 @@ export * from './src/index.js';
 export {
   DEFAULT_GEMINI_MODEL,
   DEFAULT_GEMINI_FLASH_MODEL,
+  DEFAULT_GEMINI_FLASH_LITE_MODEL,
   DEFAULT_GEMINI_EMBEDDING_MODEL,
 } from './src/config/models.js';
 export { logIdeConnection } from './src/telemetry/loggers.js';
diff --git a/packages/core/src/config/config.ts b/packages/core/src/config/config.ts
index 349a0f83..44df13a8 100644
--- a/packages/core/src/config/config.ts
+++ b/packages/core/src/config/config.ts
@@ -200,6 +200,7 @@ export interface ConfigParameters {
   trustedFolder?: boolean;
   shouldUseNodePtyShell?: boolean;
   skipNextSpeakerCheck?: boolean;
+  enablePromptCompletion?: boolean;
 }
 
 export class Config {
@@ -267,6 +268,7 @@ export class Config {
   private readonly trustedFolder: boolean | undefined;
   private readonly shouldUseNodePtyShell: boolean;
   private readonly skipNextSpeakerCheck: boolean;
+  private readonly enablePromptCompletion: boolean = false;
   private initialized: boolean = false;
   readonly storage: Storage;
 
@@ -338,6 +340,7 @@ export class Config {
     this.shouldUseNodePtyShell = params.shouldUseNodePtyShell ?? false;
     this.skipNextSpeakerCheck = params.skipNextSpeakerCheck ?? false;
     this.storage = new Storage(this.targetDir);
+    this.enablePromptCompletion = params.enablePromptCompletion ?? false;
 
     if (params.contextFileName) {
       setGeminiMdFilename(params.contextFileName);
@@ -731,6 +734,10 @@ export class Config {
     return this.skipNextSpeakerCheck;
   }
 
+  getEnablePromptCompletion(): boolean {
+    return this.enablePromptCompletion;
+  }
+
   async getGitService(): Promise<GitService> {
     if (!this.gitService) {
       this.gitService = new GitService(this.targetDir, this.storage);
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index f8cd08a8..afdba8fc 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -41,6 +41,7 @@ export * from './utils/shell-utils.js';
 export * from './utils/systemEncoding.js';
 export * from './utils/textUtils.js';
 export * from './utils/formatters.js';
+export * from './utils/generateContentResponseUtilities.js';
 export * from './utils/filesearch/fileSearch.js';
 export * from './utils/errorParsing.js';