diff --git a/cli/src/components/__tests__/multiline-input.test.tsx b/cli/src/components/__tests__/multiline-input.test.tsx
index 7fcf7eaa17..c3f8a8d5ea 100644
--- a/cli/src/components/__tests__/multiline-input.test.tsx
+++ b/cli/src/components/__tests__/multiline-input.test.tsx
@@ -1,9 +1,17 @@
+import '../../../../sdk/test/setup-env'
+
 import { describe, test, expect } from 'bun:test'
 
 import {
   getKeypadPrintableSequence,
   isKeypadEnter,
 } from '../../utils/keypad-keys'
+import {
+  findLineStart,
+  findLineEnd,
+  findPreviousWordBoundary,
+  findNextWordBoundary,
+} from '../multiline-input'
 
 /**
  * Tests for tab character cursor rendering in MultilineInput component.
@@ -656,9 +664,9 @@ describe('MultilineInput - newline keyboard shortcuts', () => {
     const ESC = '\x1b'
     return Boolean(
       key.option ||
-        (key.sequence?.length === 2 &&
-          key.sequence[0] === ESC &&
-          key.sequence[1] !== '['),
+      (key.sequence?.length === 2 &&
+        key.sequence[0] === ESC &&
+        key.sequence[1] !== '['),
     )
   }
 
@@ -689,10 +697,7 @@ describe('MultilineInput - newline keyboard shortcuts', () => {
     // So we detect it by checking for name === 'linefeed' rather than ctrl + j
     const isCtrlJ =
       lowerKeyName === 'linefeed' ||
-      (key.ctrl &&
-        !key.meta &&
-        !key.option &&
-        lowerKeyName === 'j')
+      (key.ctrl && !key.meta && !key.option && lowerKeyName === 'j')
 
     // Only handle Enter and Ctrl+J here
     if (!isEnterKey && !isCtrlJ) return 'ignore'
@@ -1130,3 +1135,70 @@ describe('MultilineInput - newline keyboard shortcuts', () => {
     expect(isAltModifier({ option: false })).toBe(false)
   })
 })
+
+describe('MultilineInput - word and line boundary operations', () => {
+  test('finds correct word boundaries backward and forward on standard text', () => {
+    const text = 'hello world from freebuff'
+    const cursor = text.length
+
+    const wordStart = findPreviousWordBoundary(text, cursor)
+    expect(wordStart).toBe(17) // starts at 'freebuff'
+
+    const wordStart2 = findPreviousWordBoundary(text, wordStart)
+    expect(wordStart2).toBe(12) // starts at 'from'
+
+    const nextWord = findNextWordBoundary(text, 0)
+    expect(nextWord).toBe(6) // starts at 'world'
+
+    const nextWord2 = findNextWordBoundary(text, nextWord)
+    expect(nextWord2).toBe(12) // starts at 'from'
+  })
+
+  test('finds word boundaries with multiple consecutive whitespace characters', () => {
+    const text = 'hello   \t\n   world'
+    expect(findPreviousWordBoundary(text, text.length)).toBe(13) // start of 'world'
+    expect(findPreviousWordBoundary(text, 13)).toBe(0) // start of 'hello'
+    expect(findNextWordBoundary(text, 0)).toBe(13) // start of 'world'
+    expect(findNextWordBoundary(text, 13)).toBe(text.length) // end of 'world'
+  })
+
+  test('handles word boundaries at text edges and empty strings', () => {
+    expect(findPreviousWordBoundary('', 0)).toBe(0)
+    expect(findNextWordBoundary('', 0)).toBe(0)
+    expect(findPreviousWordBoundary('word', 0)).toBe(0)
+    expect(findNextWordBoundary('word', 4)).toBe(4)
+
+    // Out-of-bounds cursor clamping
+    expect(findPreviousWordBoundary('word', -5)).toBe(0)
+    expect(findNextWordBoundary('word', 100)).toBe(4)
+  })
+
+  test('finds correct line boundaries for multiline input across lines', () => {
+    const text = 'line one\nline two\nline three'
+    const midCursor = 13 // in 'line two'
+
+    expect(findLineStart(text, midCursor)).toBe(9)
+    expect(findLineEnd(text, midCursor)).toBe(17)
+
+    // First line boundaries
+    expect(findLineStart(text, 2)).toBe(0)
+    expect(findLineEnd(text, 2)).toBe(8)
+
+    // Last line boundaries
+    expect(findLineStart(text, 20)).toBe(18)
+    expect(findLineEnd(text, 20)).toBe(text.length)
+  })
+
+  test('handles line boundaries on empty lines and edge boundaries', () => {
+    const emptyLineText = 'first\n\nthird'
+    // Position 6 is the empty line between the two newlines
+    expect(findLineStart(emptyLineText, 6)).toBe(6)
+    expect(findLineEnd(emptyLineText, 6)).toBe(6)
+
+    // Edge clamping
+    expect(findLineStart('', 0)).toBe(0)
+    expect(findLineEnd('', 0)).toBe(0)
+    expect(findLineStart('abc', -1)).toBe(0)
+    expect(findLineEnd('abc', 50)).toBe(3)
+  })
+})
diff --git a/cli/src/components/multiline-input.tsx b/cli/src/components/multiline-input.tsx
index c5db1c51fd..b1d3f13cd0 100644
--- a/cli/src/components/multiline-input.tsx
+++ b/cli/src/components/multiline-input.tsx
@@ -16,10 +16,7 @@ import {
 import { InputCursor } from './input-cursor'
 import { useTheme } from '../hooks/use-theme'
 import { useChatStore } from '../state/chat-store'
-import {
-  getKeypadPrintableSequence,
-  isKeypadEnter,
-} from '../utils/keypad-keys'
+import { getKeypadPrintableSequence, isKeypadEnter } from '../utils/keypad-keys'
 import { clamp } from '../utils/math'
 import {
   isLinefeedActingAsEnter,
@@ -43,7 +40,7 @@ function getPasteText(event: PasteEvent): string {
 }
 
 // Helper functions for text manipulation
-function findLineStart(text: string, cursor: number): number {
+export function findLineStart(text: string, cursor: number): number {
   let pos = Math.max(0, Math.min(cursor, text.length))
   while (pos > 0 && text[pos - 1] !== '\n') {
     pos--
@@ -51,7 +48,7 @@ function findLineStart(text: string, cursor: number): number {
   return pos
 }
 
-function findLineEnd(text: string, cursor: number): number {
+export function findLineEnd(text: string, cursor: number): number {
   let pos = Math.max(0, Math.min(cursor, text.length))
   while (pos < text.length && text[pos] !== '\n') {
     pos++
@@ -59,7 +56,7 @@ function findLineEnd(text: string, cursor: number): number {
   return pos
 }
 
-function findPreviousWordBoundary(text: string, cursor: number): number {
+export function findPreviousWordBoundary(text: string, cursor: number): number {
   let pos = Math.max(0, Math.min(cursor, text.length))
 
   // Skip whitespace backwards
@@ -75,7 +72,7 @@ function findPreviousWordBoundary(text: string, cursor: number): number {
   return pos
 }
 
-function findNextWordBoundary(text: string, cursor: number): number {
+export function findNextWordBoundary(text: string, cursor: number): number {
   let pos = Math.max(0, Math.min(cursor, text.length))
 
   // Skip non-whitespace forwards
@@ -166,9 +163,9 @@ function isAltModifier(key: KeyEvent): boolean {
   const ESC = '\x1b'
   return Boolean(
     key.option ||
-      (key.sequence?.length === 2 &&
-        key.sequence[0] === ESC &&
-        key.sequence[1] !== '['),
+    (key.sequence?.length === 2 &&
+      key.sequence[0] === ESC &&
+      key.sequence[1] !== '['),
   )
 }
 
@@ -280,9 +277,9 @@ export const MultilineInput = forwardRef<
   const prevFocusedRef = useRef(false)
   useEffect(() => {
     if (focused && !prevFocusedRef.current) {
-      (scrollBoxRef.current as FocusableScrollBox | null)?.focus?.()
+      ;(scrollBoxRef.current as FocusableScrollBox | null)?.focus?.()
     } else if (!focused && prevFocusedRef.current) {
-      (scrollBoxRef.current as FocusableScrollBox | null)?.blur?.()
+      ;(scrollBoxRef.current as FocusableScrollBox | null)?.blur?.()
     }
     prevFocusedRef.current = focused
   }, [focused])
@@ -292,10 +289,10 @@ export const MultilineInput = forwardRef<
     forwardedRef,
     () => ({
       focus: () => {
-        (scrollBoxRef.current as FocusableScrollBox | null)?.focus?.()
+        ;(scrollBoxRef.current as FocusableScrollBox | null)?.focus?.()
       },
       blur: () => {
-        (scrollBoxRef.current as FocusableScrollBox | null)?.blur?.()
+        ;(scrollBoxRef.current as FocusableScrollBox | null)?.blur?.()
       },
     }),
     [],
@@ -325,7 +322,10 @@ export const MultilineInput = forwardRef<
   }, [scrollBoxRef.current, cursorPosition, focused, cursorRow])
 
   // Helper to get current selection in original text coordinates
-  const getSelectionRange = useCallback((): { start: number; end: number } | null => {
+  const getSelectionRange = useCallback((): {
+    start: number
+    end: number
+  } | null => {
     const textBufferView = (textRef.current as any)?.textBufferView
     if (!textBufferView?.hasSelection?.() || !textBufferView?.getSelection) {
       return null
@@ -334,8 +334,14 @@ export const MultilineInput = forwardRef<
     if (!selection) return null
 
     // Convert from render positions to original text positions
-    const start = renderPositionToOriginal(value, Math.min(selection.start, selection.end))
-    const end = renderPositionToOriginal(value, Math.max(selection.start, selection.end))
+    const start = renderPositionToOriginal(
+      value,
+      Math.min(selection.start, selection.end),
+    )
+    const end = renderPositionToOriginal(
+      value,
+      Math.max(selection.start, selection.end),
+    )
 
     if (start === end) return null
     return { start, end }
@@ -348,11 +354,15 @@ export const MultilineInput = forwardRef<
   }, [renderer])
 
   // Helper to delete selected text and return new value and cursor position
-  const deleteSelection = useCallback((): { newValue: string; newCursor: number } | null => {
+  const deleteSelection = useCallback((): {
+    newValue: string
+    newCursor: number
+  } | null => {
     const selection = getSelectionRange()
     if (!selection) return null
 
-    const newValue = value.slice(0, selection.start) + value.slice(selection.end)
+    const newValue =
+      value.slice(0, selection.start) + value.slice(selection.end)
     clearSelection()
     return { newValue, newCursor: selection.start }
   }, [value, getSelectionRange, clearSelection])
@@ -462,10 +472,7 @@ export const MultilineInput = forwardRef<
       const clickRow = clickRowInViewport + scrollPosition
 
       // Find which visual line was clicked
-      const lineIndex = Math.min(
-        Math.max(0, clickRow),
-        lineStarts.length - 1,
-      )
+      const lineIndex = Math.min(Math.max(0, clickRow), lineStarts.length - 1)
 
       // Get the character range for this line
       const lineStartChar = lineStarts[lineIndex]
@@ -559,15 +566,13 @@ export const MultilineInput = forwardRef<
 
       markReturnKeySeenForKey(key)
 
-      const linefeedIsEnter = lowerKeyName === 'linefeed' && isLinefeedActingAsEnter()
+      const linefeedIsEnter =
+        lowerKeyName === 'linefeed' && isLinefeedActingAsEnter()
       const isEnterKey = isReturnOrEnter || linefeedIsEnter
 
       const isCtrlJ =
         (lowerKeyName === 'linefeed' && !linefeedIsEnter) ||
-        (key.ctrl &&
-          !key.meta &&
-          !key.option &&
-          lowerKeyName === 'j')
+        (key.ctrl && !key.meta && !key.option && lowerKeyName === 'j')
 
       // Only handle Enter and Ctrl+J here
       if (!isEnterKey && !isCtrlJ) return false
@@ -652,16 +657,14 @@ export const MultilineInput = forwardRef<
     (key: KeyEvent): boolean => {
       const lowerKeyName = (key.name ?? '').toLowerCase()
       const isAltLikeModifier = isAltModifier(key)
-      const lineStart = findLineStart(value, cursorPosition)
-      const lineEnd = findLineEnd(value, cursorPosition)
-      const wordStart = findPreviousWordBoundary(value, cursorPosition)
-      const wordEnd = findNextWordBoundary(value, cursorPosition)
 
       // Ctrl+U: Delete from cursor to beginning of current VISUAL line
       if (key.ctrl && lowerKeyName === 'u' && !key.meta && !key.option) {
         preventKeyDefault(key)
         if (handleSelectionDeletion()) return true
-        const visualLineStart = lineInfo?.lineStartCols?.[cursorRow] ?? lineStart
+        const lineStart = findLineStart(value, cursorPosition)
+        const visualLineStart =
+          lineInfo?.lineStartCols?.[cursorRow] ?? lineStart
 
         if (cursorPosition > visualLineStart) {
           const newValue =
@@ -690,8 +693,8 @@ export const MultilineInput = forwardRef<
       ) {
         preventKeyDefault(key)
         if (handleSelectionDeletion()) return true
-        const newValue =
-          value.slice(0, wordStart) + value.slice(cursorPosition)
+        const wordStart = findPreviousWordBoundary(value, cursorPosition)
+        const newValue = value.slice(0, wordStart) + value.slice(cursorPosition)
         onChange({
           text: newValue,
           cursorPosition: wordStart,
@@ -704,6 +707,7 @@ export const MultilineInput = forwardRef<
       if (key.name === 'delete' && key.meta && !isAltLikeModifier) {
         preventKeyDefault(key)
         if (handleSelectionDeletion()) return true
+        const lineStart = findLineStart(value, cursorPosition)
         const originalValue = value
         let newValue = originalValue
         let nextCursor = cursorPosition
@@ -742,6 +746,7 @@ export const MultilineInput = forwardRef<
       if (key.name === 'delete' && isAltLikeModifier) {
         preventKeyDefault(key)
         if (handleSelectionDeletion()) return true
+        const wordEnd = findNextWordBoundary(value, cursorPosition)
         const newValue = value.slice(0, cursorPosition) + value.slice(wordEnd)
         onChange({
           text: newValue,
@@ -755,6 +760,7 @@ export const MultilineInput = forwardRef<
       if (key.ctrl && lowerKeyName === 'k' && !key.meta && !key.option) {
         preventKeyDefault(key)
         if (handleSelectionDeletion()) return true
+        const lineEnd = findLineEnd(value, cursorPosition)
         const newValue = value.slice(0, cursorPosition) + value.slice(lineEnd)
         onChange({ text: newValue, cursorPosition, lastEditDueToNav: false })
         return true
@@ -826,7 +832,14 @@ export const MultilineInput = forwardRef<
 
       return false
     },
-    [value, cursorPosition, onChange, lineInfo, cursorRow, handleSelectionDeletion],
+    [
+      value,
+      cursorPosition,
+      onChange,
+      lineInfo,
+      cursorRow,
+      handleSelectionDeletion,
+    ],
   )
 
   // Handle navigation keys (arrows, home, end, word navigation, emacs bindings)
@@ -834,35 +847,11 @@ export const MultilineInput = forwardRef<
     (key: KeyEvent): boolean => {
       const lowerKeyName = (key.name ?? '').toLowerCase()
       const isAltLikeModifier = isAltModifier(key)
-      const logicalLineStart = findLineStart(value, cursorPosition)
-      const logicalLineEnd = findLineEnd(value, cursorPosition)
-      const wordStart = findPreviousWordBoundary(value, cursorPosition)
-      const wordEnd = findNextWordBoundary(value, cursorPosition)
-
-      // Read lineInfo inside the callback to get current value (not stale from closure)
-      const currentLineInfo = textRef.current
-        ? ((textRef.current as any).textBufferView as TextBufferView)?.lineInfo
-        : null
-
-      // Calculate visual line boundaries from lineInfo (accounts for word wrap)
-      // Fall back to logical line boundaries if visual info is unavailable
-      const lineStarts = currentLineInfo?.lineStartCols ?? []
-      const visualLineIndex = lineStarts.findLastIndex(
-        (start) => start <= cursorPosition,
-      )
-      const visualLineStart = visualLineIndex >= 0
-        ? lineStarts[visualLineIndex]
-        : logicalLineStart
-      const visualLineEnd = lineStarts[visualLineIndex + 1] !== undefined
-        ? lineStarts[visualLineIndex + 1] - 1
-        : logicalLineEnd
 
       // Alt+Left/B: Word left
-      if (
-        isAltLikeModifier &&
-        (key.name === 'left' || lowerKeyName === 'b')
-      ) {
+      if (isAltLikeModifier && (key.name === 'left' || lowerKeyName === 'b')) {
         preventKeyDefault(key)
+        const wordStart = findPreviousWordBoundary(value, cursorPosition)
         onChange({
           text: value,
           cursorPosition: wordStart,
@@ -872,11 +861,9 @@ export const MultilineInput = forwardRef<
       }
 
       // Alt+Right/F: Word right
-      if (
-        isAltLikeModifier &&
-        (key.name === 'right' || lowerKeyName === 'f')
-      ) {
+      if (isAltLikeModifier && (key.name === 'right' || lowerKeyName === 'f')) {
         preventKeyDefault(key)
+        const wordEnd = findNextWordBoundary(value, cursorPosition)
         onChange({
           text: value,
           cursorPosition: wordEnd,
@@ -885,6 +872,27 @@ export const MultilineInput = forwardRef<
         return true
       }
 
+      // Helper to compute visual line boundaries and line starts lazily when needed
+      const getVisualLineInfo = () => {
+        const currentLineInfo = textRef.current
+          ? ((textRef.current as any).textBufferView as TextBufferView)
+              ?.lineInfo
+          : null
+        const lineStarts = currentLineInfo?.lineStartCols ?? []
+        const visualLineIndex = lineStarts.findLastIndex(
+          (start) => start <= cursorPosition,
+        )
+        const visualLineStart =
+          visualLineIndex >= 0
+            ? lineStarts[visualLineIndex]
+            : findLineStart(value, cursorPosition)
+        const visualLineEnd =
+          visualLineIndex >= 0 && lineStarts[visualLineIndex + 1] !== undefined
+            ? lineStarts[visualLineIndex + 1] - 1
+            : findLineEnd(value, cursorPosition)
+        return { lineStarts, visualLineStart, visualLineEnd }
+      }
+
       // Cmd+Left, Ctrl+A, or Home: Line start
       if (
         (key.meta && key.name === 'left' && !isAltLikeModifier) ||
@@ -892,6 +900,7 @@ export const MultilineInput = forwardRef<
         (key.name === 'home' && !key.ctrl && !key.meta)
       ) {
         preventKeyDefault(key)
+        const { visualLineStart } = getVisualLineInfo()
         onChange({
           text: value,
           cursorPosition: visualLineStart,
@@ -907,6 +916,7 @@ export const MultilineInput = forwardRef<
         (key.name === 'end' && !key.ctrl && !key.meta)
       ) {
         preventKeyDefault(key)
+        const { visualLineEnd } = getVisualLineInfo()
         onChange({
           text: value,
           cursorPosition: visualLineEnd,
@@ -978,6 +988,7 @@ export const MultilineInput = forwardRef<
       // Up arrow (no modifiers)
       if (key.name === 'up' && !key.ctrl && !key.meta && !key.option) {
         preventKeyDefault(key)
+        const { lineStarts } = getVisualLineInfo()
         const desiredIndex = getOrSetStickyColumn(lineStarts, !shouldHighlight)
         onChange({
           text: value,
@@ -996,6 +1007,7 @@ export const MultilineInput = forwardRef<
       // Down arrow (no modifiers)
       if (key.name === 'down' && !key.ctrl && !key.meta && !key.option) {
         preventKeyDefault(key)
+        const { lineStarts } = getVisualLineInfo()
         const desiredIndex = getOrSetStickyColumn(lineStarts, !shouldHighlight)
         onChange({
           text: value,
@@ -1013,7 +1025,14 @@ export const MultilineInput = forwardRef<
 
       return false
     },
-    [value, cursorPosition, onChange, moveCursor, shouldHighlight, getOrSetStickyColumn],
+    [
+      value,
+      cursorPosition,
+      onChange,
+      moveCursor,
+      shouldHighlight,
+      getOrSetStickyColumn,
+    ],
   )
 
   // Handle character input (regular chars, tab, and IME/multi-byte input)
@@ -1053,7 +1072,8 @@ export const MultilineInput = forwardRef<
   // gives enough time for split paste sequences to arrive.
   useEffect(() => {
     const cliRenderer = appContext.renderer as Record<string, unknown> | null
-    const stdinBuffer = cliRenderer?._stdinBuffer as Record<string, unknown> | undefined
+    const stdinBuffer = cliRenderer?._stdinBuffer as
+      Record<string, unknown> | undefined
     if (stdinBuffer && typeof stdinBuffer.timeoutMs === 'number') {
       stdinBuffer.timeoutMs = 100
     }
@@ -1080,7 +1100,9 @@ export const MultilineInput = forwardRef<
       // Reset dedup flag after microtask so scrollbox handler (which fires
       // synchronously after global listeners) sees it as handled, but future
       // paste events are not blocked.
-      queueMicrotask(() => { pasteHandledRef.current = false })
+      queueMicrotask(() => {
+        pasteHandledRef.current = false
+      })
     }
 
     keyHandler.on('paste', handlePaste)
@@ -1127,8 +1149,7 @@ export const MultilineInput = forwardRef<
     const safeMaxHeight = Math.max(1, maxHeight)
     const effectiveMinHeight = Math.max(1, Math.min(minHeight, safeMaxHeight))
 
-    const totalLines =
-      lineInfo === null ? 0 : lineInfo.lineStartCols.length
+    const totalLines = lineInfo === null ? 0 : lineInfo.lineStartCols.length
 
     // Add bottom gutter when cursor is on line 2 of exactly 2 lines
     const gutterEnabled =