init claude-code

ink/hooks/use-animation-frame.ts

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+import { useContext, useEffect, useState } from 'react'
+import { ClockContext } from '../components/ClockContext.js'
+import type { DOMElement } from '../dom.js'
+import { useTerminalViewport } from './use-terminal-viewport.js'
+
+/**
+ * Hook for synchronized animations that pause when offscreen.
+ *
+ * Returns a ref to attach to the animated element and the current animation time.
+ * All instances share the same clock, so animations stay in sync.
+ * The clock only runs when at least one keepAlive subscriber exists.
+ *
+ * Pass `null` to pause — unsubscribes from the clock so no ticks fire.
+ * Time freezes at the last value and resumes from the current clock time
+ * when a number is passed again.
+ *
+ * @param intervalMs - How often to update, or null to pause
+ * @returns [ref, time] - Ref to attach to element, elapsed time in ms
+ *
+ * @example
+ * function Spinner() {
+ *   const [ref, time] = useAnimationFrame(120)
+ *   const frame = Math.floor(time / 120) % FRAMES.length
+ *   return <Box ref={ref}>{FRAMES[frame]}</Box>
+ * }
+ *
+ * The clock automatically slows when the terminal is blurred,
+ * so consumers don't need to handle focus state.
+ */
+export function useAnimationFrame(
+  intervalMs: number | null = 16,
+): [ref: (element: DOMElement | null) => void, time: number] {
+  const clock = useContext(ClockContext)
+  const [viewportRef, { isVisible }] = useTerminalViewport()
+  const [time, setTime] = useState(() => clock?.now() ?? 0)
+
+  const active = isVisible && intervalMs !== null
+
+  useEffect(() => {
+    if (!clock || !active) return
+
+    let lastUpdate = clock.now()
+
+    const onChange = (): void => {
+      const now = clock.now()
+      if (now - lastUpdate >= intervalMs!) {
+        lastUpdate = now
+        setTime(now)
+      }
+    }
+
+    // keepAlive: true — visible animations drive the clock
+    return clock.subscribe(onChange, true)
+  }, [clock, intervalMs, active])
+
+  return [viewportRef, time]
+}

ink/hooks/use-app.ts

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+import { useContext } from 'react'
+import AppContext from '../components/AppContext.js'
+
+/**
+ * `useApp` is a React hook, which exposes a method to manually exit the app (unmount).
+ */
+const useApp = () => useContext(AppContext)
+export default useApp

ink/hooks/use-declared-cursor.ts

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+import { useCallback, useContext, useLayoutEffect, useRef } from 'react'
+import CursorDeclarationContext from '../components/CursorDeclarationContext.js'
+import type { DOMElement } from '../dom.js'
+
+/**
+ * Declares where the terminal cursor should be parked after each frame.
+ *
+ * Terminal emulators render IME preedit text at the physical cursor
+ * position, and screen readers / screen magnifiers track the native
+ * cursor — so parking it at the text input's caret makes CJK input
+ * appear inline and lets accessibility tools follow the input.
+ *
+ * Returns a ref callback to attach to the Box that contains the input.
+ * The declared (line, column) is interpreted relative to that Box's
+ * nodeCache rect (populated by renderNodeToOutput).
+ *
+ * Timing: Both ref attach and useLayoutEffect fire in React's layout
+ * phase — after resetAfterCommit calls scheduleRender. scheduleRender
+ * defers onRender via queueMicrotask, so onRender runs AFTER layout
+ * effects commit and reads the fresh declaration on the first frame
+ * (no one-keystroke lag). Test env uses onImmediateRender (synchronous,
+ * no microtask), so tests compensate by calling ink.onRender()
+ * explicitly after render.
+ */
+export function useDeclaredCursor({
+  line,
+  column,
+  active,
+}: {
+  line: number
+  column: number
+  active: boolean
+}): (element: DOMElement | null) => void {
+  const setCursorDeclaration = useContext(CursorDeclarationContext)
+  const nodeRef = useRef<DOMElement | null>(null)
+
+  const setNode = useCallback((node: DOMElement | null) => {
+    nodeRef.current = node
+  }, [])
+
+  // When active, set unconditionally. When inactive, clear conditionally
+  // (only if the currently-declared node is ours). The node-identity check
+  // handles two hazards:
+  //   1. A memo()ized active instance elsewhere (e.g. the search input in
+  //      a memo'd Footer) doesn't re-render this commit — an inactive
+  //      instance re-rendering here must not clobber it.
+  //   2. Sibling handoff (menu focus moving between list items) — when
+  //      focus moves opposite to sibling order, the newly-inactive item's
+  //      effect runs AFTER the newly-active item's set. Without the node
+  //      check it would clobber.
+  // No dep array: must re-declare every commit so the active instance
+  // re-claims the declaration after another instance's unmount-cleanup or
+  // sibling handoff nulls it.
+  useLayoutEffect(() => {
+    const node = nodeRef.current
+    if (active && node) {
+      setCursorDeclaration({ relativeX: column, relativeY: line, node })
+    } else {
+      setCursorDeclaration(null, node)
+    }
+  })
+
+  // Clear on unmount (conditionally — another instance may own by then).
+  // Separate effect with empty deps so cleanup only fires once — not on
+  // every line/column change, which would transiently null between commits.
+  useLayoutEffect(() => {
+    return () => {
+      setCursorDeclaration(null, nodeRef.current)
+    }
+  }, [setCursorDeclaration])
+
+  return setNode
+}

ink/hooks/use-input.ts

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+import { useEffect, useLayoutEffect } from 'react'
+import { useEventCallback } from 'usehooks-ts'
+import type { InputEvent, Key } from '../events/input-event.js'
+import useStdin from './use-stdin.js'
+
+type Handler = (input: string, key: Key, event: InputEvent) => void
+
+type Options = {
+  /**
+   * Enable or disable capturing of user input.
+   * Useful when there are multiple useInput hooks used at once to avoid handling the same input several times.
+   *
+   * @default true
+   */
+  isActive?: boolean
+}
+
+/**
+ * This hook is used for handling user input.
+ * It's a more convenient alternative to using `StdinContext` and listening to `data` events.
+ * The callback you pass to `useInput` is called for each character when user enters any input.
+ * However, if user pastes text and it's more than one character, the callback will be called only once and the whole string will be passed as `input`.
+ *
+ * ```
+ * import {useInput} from 'ink';
+ *
+ * const UserInput = () => {
+ *   useInput((input, key) => {
+ *     if (input === 'q') {
+ *       // Exit program
+ *     }
+ *
+ *     if (key.leftArrow) {
+ *       // Left arrow key pressed
+ *     }
+ *   });
+ *
+ *   return …
+ * };
+ * ```
+ */
+const useInput = (inputHandler: Handler, options: Options = {}) => {
+  const { setRawMode, internal_exitOnCtrlC, internal_eventEmitter } = useStdin()
+
+  // useLayoutEffect (not useEffect) so that raw mode is enabled synchronously
+  // during React's commit phase, before render() returns. With useEffect, raw
+  // mode setup is deferred to the next event loop tick via React's scheduler,
+  // leaving the terminal in cooked mode — keystrokes echo and the cursor is
+  // visible until the effect fires.
+  useLayoutEffect(() => {
+    if (options.isActive === false) {
+      return
+    }
+
+    setRawMode(true)
+
+    return () => {
+      setRawMode(false)
+    }
+  }, [options.isActive, setRawMode])
+
+  // Register the listener once on mount so its slot in the EventEmitter's
+  // listener array is stable. If isActive were in the effect's deps, the
+  // listener would re-append on false→true, moving it behind listeners
+  // that registered while it was inactive — breaking
+  // stopImmediatePropagation() ordering. useEventCallback keeps the
+  // reference stable while reading latest isActive/inputHandler from
+  // closure (it syncs via useLayoutEffect, so it's compiler-safe).
+  const handleData = useEventCallback((event: InputEvent) => {
+    if (options.isActive === false) {
+      return
+    }
+    const { input, key } = event
+
+    // If app is not supposed to exit on Ctrl+C, then let input listener handle it
+    // Note: discreteUpdates is called at the App level when emitting events,
+    // so all listeners are already within a high-priority update context.
+    if (!(input === 'c' && key.ctrl) || !internal_exitOnCtrlC) {
+      inputHandler(input, key, event)
+    }
+  })
+
+  useEffect(() => {
+    internal_eventEmitter?.on('input', handleData)
+
+    return () => {
+      internal_eventEmitter?.removeListener('input', handleData)
+    }
+  }, [internal_eventEmitter, handleData])
+}
+
+export default useInput

ink/hooks/use-interval.ts

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+import { useContext, useEffect, useRef, useState } from 'react'
+import { ClockContext } from '../components/ClockContext.js'
+
+/**
+ * Returns the clock time, updating at the given interval.
+ * Subscribes as non-keepAlive — won't keep the clock alive on its own,
+ * but updates whenever a keepAlive subscriber (e.g. the spinner)
+ * is driving the clock.
+ *
+ * Use this to drive pure time-based computations (shimmer position,
+ * frame index) from the shared clock.
+ */
+export function useAnimationTimer(intervalMs: number): number {
+  const clock = useContext(ClockContext)
+  const [time, setTime] = useState(() => clock?.now() ?? 0)
+
+  useEffect(() => {
+    if (!clock) return
+
+    let lastUpdate = clock.now()
+
+    const onChange = (): void => {
+      const now = clock.now()
+      if (now - lastUpdate >= intervalMs) {
+        lastUpdate = now
+        setTime(now)
+      }
+    }
+
+    return clock.subscribe(onChange, false)
+  }, [clock, intervalMs])
+
+  return time
+}
+
+/**
+ * Interval hook backed by the shared Clock.
+ *
+ * Unlike `useInterval` from `usehooks-ts` (which creates its own setInterval),
+ * this piggybacks on the single shared clock so all timers consolidate into
+ * one wake-up. Pass `null` for intervalMs to pause.
+ */
+export function useInterval(
+  callback: () => void,
+  intervalMs: number | null,
+): void {
+  const callbackRef = useRef(callback)
+  callbackRef.current = callback
+
+  const clock = useContext(ClockContext)
+
+  useEffect(() => {
+    if (!clock || intervalMs === null) return
+
+    let lastUpdate = clock.now()
+
+    const onChange = (): void => {
+      const now = clock.now()
+      if (now - lastUpdate >= intervalMs) {
+        lastUpdate = now
+        callbackRef.current()
+      }
+    }
+
+    return clock.subscribe(onChange, false)
+  }, [clock, intervalMs])
+}

ink/hooks/use-search-highlight.ts

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+import { useContext, useMemo } from 'react'
+import StdinContext from '../components/StdinContext.js'
+import type { DOMElement } from '../dom.js'
+import instances from '../instances.js'
+import type { MatchPosition } from '../render-to-screen.js'
+
+/**
+ * Set the search highlight query on the Ink instance. Non-empty → all
+ * visible occurrences are inverted on the next frame (SGR 7, screen-buffer
+ * overlay, same damage machinery as selection). Empty → clears.
+ *
+ * This is a screen-space highlight — it matches the RENDERED text, not the
+ * source message text. Works for anything visible (bash output, file paths,
+ * error messages) regardless of where it came from in the message tree. A
+ * query that matched in source but got truncated/ellipsized in rendering
+ * won't highlight; that's acceptable — we highlight what you see.
+ */
+export function useSearchHighlight(): {
+  setQuery: (query: string) => void
+  /** Paint an existing DOM subtree (from the MAIN tree) to a fresh
+   *  Screen at its natural height, scan. Element-relative positions
+   *  (row 0 = element top). Zero context duplication — the element
+   *  IS the one built with all real providers. */
+  scanElement: (el: DOMElement) => MatchPosition[]
+  /** Position-based CURRENT highlight. Every frame writes yellow at
+   *  positions[currentIdx] + rowOffset. The scan-highlight (inverse on
+   *  all matches) still runs — this overlays on top. rowOffset tracks
+   *  scroll; positions stay stable (message-relative). null clears. */
+  setPositions: (
+    state: {
+      positions: MatchPosition[]
+      rowOffset: number
+      currentIdx: number
+    } | null,
+  ) => void
+} {
+  useContext(StdinContext) // anchor to App subtree for hook rules
+  const ink = instances.get(process.stdout)
+  return useMemo(() => {
+    if (!ink) {
+      return {
+        setQuery: () => {},
+        scanElement: () => [],
+        setPositions: () => {},
+      }
+    }
+    return {
+      setQuery: (query: string) => ink.setSearchHighlight(query),
+      scanElement: (el: DOMElement) => ink.scanElementSubtree(el),
+      setPositions: state => ink.setSearchPositions(state),
+    }
+  }, [ink])
+}

ink/hooks/use-selection.ts

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+import { useContext, useMemo, useSyncExternalStore } from 'react'
+import StdinContext from '../components/StdinContext.js'
+import instances from '../instances.js'
+import {
+  type FocusMove,
+  type SelectionState,
+  shiftAnchor,
+} from '../selection.js'
+
+/**
+ * Access to text selection operations on the Ink instance (fullscreen only).
+ * Returns no-op functions when fullscreen mode is disabled.
+ */
+export function useSelection(): {
+  copySelection: () => string
+  /** Copy without clearing the highlight (for copy-on-select). */
+  copySelectionNoClear: () => string
+  clearSelection: () => void
+  hasSelection: () => boolean
+  /** Read the raw mutable selection state (for drag-to-scroll). */
+  getState: () => SelectionState | null
+  /** Subscribe to selection mutations (start/update/finish/clear). */
+  subscribe: (cb: () => void) => () => void
+  /** Shift the anchor row by dRow, clamped to [minRow, maxRow]. */
+  shiftAnchor: (dRow: number, minRow: number, maxRow: number) => void
+  /** Shift anchor AND focus by dRow (keyboard scroll: whole selection
+   *  tracks content). Clamped points get col reset to the full-width edge
+   *  since their content was captured by captureScrolledRows. Reads
+   *  screen.width from the ink instance for the col-reset boundary. */
+  shiftSelection: (dRow: number, minRow: number, maxRow: number) => void
+  /** Keyboard selection extension (shift+arrow): move focus, anchor fixed.
+   *  Left/right wrap across rows; up/down clamp at viewport edges. */
+  moveFocus: (move: FocusMove) => void
+  /** Capture text from rows about to scroll out of the viewport (call
+   *  BEFORE scrollBy so the screen buffer still has the outgoing rows). */
+  captureScrolledRows: (
+    firstRow: number,
+    lastRow: number,
+    side: 'above' | 'below',
+  ) => void
+  /** Set the selection highlight bg color (theme-piping; solid bg
+   *  replaces the old SGR-7 inverse so syntax highlighting stays readable
+   *  under selection). Call once on mount + whenever theme changes. */
+  setSelectionBgColor: (color: string) => void
+} {
+  // Look up the Ink instance via stdout — same pattern as instances map.
+  // StdinContext is available (it's always provided), and the Ink instance
+  // is keyed by stdout which we can get from process.stdout since there's
+  // only one Ink instance per process in practice.
+  useContext(StdinContext) // anchor to App subtree for hook rules
+  const ink = instances.get(process.stdout)
+  // Memoize so callers can safely use the return value in dependency arrays.
+  // ink is a singleton per stdout — stable across renders.
+  return useMemo(() => {
+    if (!ink) {
+      return {
+        copySelection: () => '',
+        copySelectionNoClear: () => '',
+        clearSelection: () => {},
+        hasSelection: () => false,
+        getState: () => null,
+        subscribe: () => () => {},
+        shiftAnchor: () => {},
+        shiftSelection: () => {},
+        moveFocus: () => {},
+        captureScrolledRows: () => {},
+        setSelectionBgColor: () => {},
+      }
+    }
+    return {
+      copySelection: () => ink.copySelection(),
+      copySelectionNoClear: () => ink.copySelectionNoClear(),
+      clearSelection: () => ink.clearTextSelection(),
+      hasSelection: () => ink.hasTextSelection(),
+      getState: () => ink.selection,
+      subscribe: (cb: () => void) => ink.subscribeToSelectionChange(cb),
+      shiftAnchor: (dRow: number, minRow: number, maxRow: number) =>
+        shiftAnchor(ink.selection, dRow, minRow, maxRow),
+      shiftSelection: (dRow, minRow, maxRow) =>
+        ink.shiftSelectionForScroll(dRow, minRow, maxRow),
+      moveFocus: (move: FocusMove) => ink.moveSelectionFocus(move),
+      captureScrolledRows: (firstRow, lastRow, side) =>
+        ink.captureScrolledRows(firstRow, lastRow, side),
+      setSelectionBgColor: (color: string) => ink.setSelectionBgColor(color),
+    }
+  }, [ink])
+}
+
+const NO_SUBSCRIBE = () => () => {}
+const ALWAYS_FALSE = () => false
+
+/**
+ * Reactive selection-exists state. Re-renders the caller when a text
+ * selection is created or cleared. Always returns false outside
+ * fullscreen mode (selection is only available in alt-screen).
+ */
+export function useHasSelection(): boolean {
+  useContext(StdinContext)
+  const ink = instances.get(process.stdout)
+  return useSyncExternalStore(
+    ink ? ink.subscribeToSelectionChange : NO_SUBSCRIBE,
+    ink ? ink.hasTextSelection : ALWAYS_FALSE,
+  )
+}

ink/hooks/use-stdin.ts

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+import { useContext } from 'react'
+import StdinContext from '../components/StdinContext.js'
+
+/**
+ * `useStdin` is a React hook, which exposes stdin stream.
+ */
+const useStdin = () => useContext(StdinContext)
+export default useStdin

ink/hooks/use-tab-status.ts

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+import { useContext, useEffect, useRef } from 'react'
+import {
+  CLEAR_TAB_STATUS,
+  supportsTabStatus,
+  tabStatus,
+  wrapForMultiplexer,
+} from '../termio/osc.js'
+import type { Color } from '../termio/types.js'
+import { TerminalWriteContext } from '../useTerminalNotification.js'
+
+export type TabStatusKind = 'idle' | 'busy' | 'waiting'
+
+const rgb = (r: number, g: number, b: number): Color => ({
+  type: 'rgb',
+  r,
+  g,
+  b,
+})
+
+// Per the OSC 21337 usage guide's suggested mapping.
+const TAB_STATUS_PRESETS: Record<
+  TabStatusKind,
+  { indicator: Color; status: string; statusColor: Color }
+> = {
+  idle: {
+    indicator: rgb(0, 215, 95),
+    status: 'Idle',
+    statusColor: rgb(136, 136, 136),
+  },
+  busy: {
+    indicator: rgb(255, 149, 0),
+    status: 'Working…',
+    statusColor: rgb(255, 149, 0),
+  },
+  waiting: {
+    indicator: rgb(95, 135, 255),
+    status: 'Waiting',
+    statusColor: rgb(95, 135, 255),
+  },
+}
+
+/**
+ * Declaratively set the tab-status indicator (OSC 21337).
+ *
+ * Emits a colored dot + short status text to the tab sidebar. Terminals
+ * that don't support OSC 21337 discard the sequence silently, so this is
+ * safe to call unconditionally. Wrapped for tmux/screen passthrough.
+ *
+ * Pass `null` to opt out. If a status was previously set, transitioning to
+ * `null` emits CLEAR_TAB_STATUS so toggling off mid-session doesn't leave
+ * a stale dot. Process-exit cleanup is handled by ink.tsx's unmount path.
+ */
+export function useTabStatus(kind: TabStatusKind | null): void {
+  const writeRaw = useContext(TerminalWriteContext)
+  const prevKindRef = useRef<TabStatusKind | null>(null)
+
+  useEffect(() => {
+    // When kind transitions from non-null to null (e.g. user toggles off
+    // showStatusInTerminalTab mid-session), clear the stale dot.
+    if (kind === null) {
+      if (prevKindRef.current !== null && writeRaw && supportsTabStatus()) {
+        writeRaw(wrapForMultiplexer(CLEAR_TAB_STATUS))
+      }
+      prevKindRef.current = null
+      return
+    }
+
+    prevKindRef.current = kind
+    if (!writeRaw || !supportsTabStatus()) return
+    writeRaw(wrapForMultiplexer(tabStatus(TAB_STATUS_PRESETS[kind])))
+  }, [kind, writeRaw])
+}

ink/hooks/use-terminal-focus.ts

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+import { useContext } from 'react'
+import TerminalFocusContext from '../components/TerminalFocusContext.js'
+
+/**
+ * Hook to check if the terminal has focus.
+ *
+ * Uses DECSET 1004 focus reporting - the terminal sends escape sequences
+ * when it gains or loses focus. These are handled automatically
+ * by Ink and filtered from useInput.
+ *
+ * @returns true if the terminal is focused (or focus state is unknown)
+ */
+export function useTerminalFocus(): boolean {
+  const { isTerminalFocused } = useContext(TerminalFocusContext)
+  return isTerminalFocused
+}

ink/hooks/use-terminal-title.ts

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+import { useContext, useEffect } from 'react'
+import stripAnsi from 'strip-ansi'
+import { OSC, osc } from '../termio/osc.js'
+import { TerminalWriteContext } from '../useTerminalNotification.js'
+
+/**
+ * Declaratively set the terminal tab/window title.
+ *
+ * Pass a string to set the title. ANSI escape sequences are stripped
+ * automatically so callers don't need to know about terminal encoding.
+ * Pass `null` to opt out — the hook becomes a no-op and leaves the
+ * terminal title untouched.
+ *
+ * On Windows, uses `process.title` (classic conhost doesn't support OSC).
+ * Elsewhere, writes OSC 0 (set title+icon) via Ink's stdout.
+ */
+export function useTerminalTitle(title: string | null): void {
+  const writeRaw = useContext(TerminalWriteContext)
+
+  useEffect(() => {
+    if (title === null || !writeRaw) return
+
+    const clean = stripAnsi(title)
+
+    if (process.platform === 'win32') {
+      process.title = clean
+    } else {
+      writeRaw(osc(OSC.SET_TITLE_AND_ICON, clean))
+    }
+  }, [title, writeRaw])
+}

ink/hooks/use-terminal-viewport.ts

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+import { useCallback, useContext, useLayoutEffect, useRef } from 'react'
+import { TerminalSizeContext } from '../components/TerminalSizeContext.js'
+import type { DOMElement } from '../dom.js'
+
+type ViewportEntry = {
+  /**
+   * Whether the element is currently within the terminal viewport
+   */
+  isVisible: boolean
+}
+
+/**
+ * Hook to detect if a component is within the terminal viewport.
+ *
+ * Returns a callback ref and a viewport entry object.
+ * Attach the ref to the component you want to track.
+ *
+ * The entry is updated during the layout phase (useLayoutEffect) so callers
+ * always read fresh values during render. Visibility changes do NOT trigger
+ * re-renders on their own — callers that re-render for other reasons (e.g.
+ * animation ticks, state changes) will pick up the latest value naturally.
+ * This avoids infinite update loops when combined with other layout effects
+ * that also call setState.
+ *
+ * @example
+ * const [ref, entry] = useTerminalViewport()
+ * return <Box ref={ref}><Animation enabled={entry.isVisible}>...</Animation></Box>
+ */
+export function useTerminalViewport(): [
+  ref: (element: DOMElement | null) => void,
+  entry: ViewportEntry,
+] {
+  const terminalSize = useContext(TerminalSizeContext)
+  const elementRef = useRef<DOMElement | null>(null)
+  const entryRef = useRef<ViewportEntry>({ isVisible: true })
+
+  const setElement = useCallback((el: DOMElement | null) => {
+    elementRef.current = el
+  }, [])
+
+  // Runs on every render because yoga layout values can change
+  // without React being aware. Only updates the ref — no setState
+  // to avoid cascading re-renders during the commit phase.
+  // Walks the DOM ancestor chain fresh each time to avoid holding stale
+  // references after yoga tree rebuilds.
+  useLayoutEffect(() => {
+    const element = elementRef.current
+    if (!element?.yogaNode || !terminalSize) {
+      return
+    }
+
+    const height = element.yogaNode.getComputedHeight()
+    const rows = terminalSize.rows
+
+    // Walk the DOM parent chain (not yoga.getParent()) so we can detect
+    // scroll containers and subtract their scrollTop. Yoga computes layout
+    // positions without scroll offset — scrollTop is applied at render time.
+    // Without this, an element inside a ScrollBox whose yoga position exceeds
+    // terminalRows would be considered offscreen even when scrolled into view
+    // (e.g., the spinner in fullscreen mode after enough messages accumulate).
+    let absoluteTop = element.yogaNode.getComputedTop()
+    let parent: DOMElement | undefined = element.parentNode
+    let root = element.yogaNode
+    while (parent) {
+      if (parent.yogaNode) {
+        absoluteTop += parent.yogaNode.getComputedTop()
+        root = parent.yogaNode
+      }
+      // scrollTop is only ever set on scroll containers (by ScrollBox + renderer).
+      // Non-scroll nodes have undefined scrollTop → falsy fast-path.
+      if (parent.scrollTop) absoluteTop -= parent.scrollTop
+      parent = parent.parentNode
+    }
+
+    // Only the root's height matters
+    const screenHeight = root.getComputedHeight()
+
+    const bottom = absoluteTop + height
+    // When content overflows the viewport (screenHeight > rows), the
+    // cursor-restore at frame end scrolls one extra row into scrollback.
+    // log-update.ts accounts for this with scrollbackRows = viewportY + 1.
+    // We must match, otherwise an element at the boundary is considered
+    // "visible" here (animation keeps ticking) but its row is treated as
+    // scrollback by log-update (content change → full reset → flicker).
+    const cursorRestoreScroll = screenHeight > rows ? 1 : 0
+    const viewportY = Math.max(0, screenHeight - rows) + cursorRestoreScroll
+    const viewportBottom = viewportY + rows
+    const visible = bottom > viewportY && absoluteTop < viewportBottom
+
+    if (visible !== entryRef.current.isVisible) {
+      entryRef.current = { isVisible: visible }
+    }
+  })
+
+  return [setElement, entryRef.current]
+}