fix(tui): restore prompt rendering on startup (#498)

* fix(tui): restore prompt rendering on startup

* test(tui): document render-time command split

* fix(tui): reduce ghostty prompt repaint scope

src/ink/components/App.tsx

@@ -115,7 +115,10 @@ export default class App extends PureComponent<Props, State> {
   keyParseState = INITIAL_STATE;
   // Timer for flushing incomplete escape sequences
   incompleteEscapeTimer: NodeJS.Timeout | null = null;
-  stdinMode: 'readable' | 'data' = process.env.OPENCLAUDE_USE_READABLE_STDIN === '1' ? 'readable' : 'data';
+  // Default to readable-mode stdin (legacy Ink behavior). The data-mode path
+  // is kept as an explicit opt-in because some terminals can enter a state
+  // where startup input appears frozen when data mode is the default.
+  stdinMode: 'readable' | 'data' = process.env.OPENCLAUDE_USE_DATA_STDIN === '1' || process.env.OPENCLAUDE_USE_READABLE_STDIN === '0' ? 'data' : 'readable';
   // Timeout durations for incomplete sequences (ms)
   readonly NORMAL_TIMEOUT = 50; // Short timeout for regular esc sequences
   readonly PASTE_TIMEOUT = 500; // Longer timeout for paste operations

src/ink/ink.tsx

@@ -33,7 +33,7 @@ import createRenderer, { type Renderer } from './renderer.js';
 import { CellWidth, CharPool, cellAt, createScreen, HyperlinkPool, isEmptyCellAt, migrateScreenPools, StylePool } from './screen.js';
 import { applySearchHighlight } from './searchHighlight.js';
 import { applySelectionOverlay, captureScrolledRows, clearSelection, createSelectionState, extendSelection, type FocusMove, findPlainTextUrlAt, getSelectedText, hasSelection, moveFocus, type SelectionState, selectLineAt, selectWordAt, shiftAnchor, shiftSelection, shiftSelectionForFollow, startSelection, updateSelection } from './selection.js';
-import { SYNC_OUTPUT_SUPPORTED, supportsExtendedKeys, type Terminal, writeDiffToTerminal } from './terminal.js';
+import { shouldSkipMainScreenSyncMarkers, shouldUseMainScreenRewrite, SYNC_OUTPUT_SUPPORTED, supportsExtendedKeys, type Terminal, writeDiffToTerminal } from './terminal.js';
 import { CURSOR_HOME, cursorMove, cursorPosition, DISABLE_KITTY_KEYBOARD, DISABLE_MODIFY_OTHER_KEYS, ENABLE_KITTY_KEYBOARD, ENABLE_MODIFY_OTHER_KEYS, ERASE_SCREEN } from './termio/csi.js';
 import { DBP, DFE, DISABLE_MOUSE_TRACKING, ENABLE_MOUSE_TRACKING, ENTER_ALT_SCREEN, EXIT_ALT_SCREEN, SHOW_CURSOR } from './termio/dec.js';
 import { CLEAR_ITERM2_PROGRESS, CLEAR_TAB_STATUS, setClipboard, supportsTabStatus, wrapForMultiplexer } from './termio/osc.js';
@@ -609,12 +609,13 @@ export default class Ink {
       };
     }
     const tDiff = performance.now();
+    const rewriteMainScreen = !this.altScreenActive && shouldUseMainScreenRewrite();
     const diff = this.log.render(prevFrame, frame, this.altScreenActive,
     // DECSTBM needs BSU/ESU atomicity — without it the outer terminal
     // renders the scrolled-but-not-yet-repainted intermediate state.
     // tmux is the main case (re-emits DECSTBM with its own timing and
     // doesn't implement DEC 2026, so SYNC_OUTPUT_SUPPORTED is false).
-    SYNC_OUTPUT_SUPPORTED);
+    SYNC_OUTPUT_SUPPORTED, rewriteMainScreen);
     const diffMs = performance.now() - tDiff;
     // Swap buffers
     this.backFrame = this.frontFrame;
@@ -759,7 +760,8 @@ export default class Ink {
       }
     }
     const tWrite = performance.now();
-    writeDiffToTerminal(this.terminal, optimized, this.altScreenActive && !SYNC_OUTPUT_SUPPORTED);
+    const skipSyncMarkers = this.altScreenActive ? !SYNC_OUTPUT_SUPPORTED : rewriteMainScreen || shouldSkipMainScreenSyncMarkers();
+    writeDiffToTerminal(this.terminal, optimized, skipSyncMarkers);
     const writeMs = performance.now() - tWrite;
 
     // Update blit safety for the NEXT frame. The frame just rendered

src/ink/log-update.test.ts

@@ -0,0 +1,125 @@
+import { expect, test } from 'bun:test'
+
+import type { Frame } from './frame.ts'
+import { LogUpdate } from './log-update.ts'
+import {
+  CellWidth,
+  CharPool,
+  createScreen,
+  HyperlinkPool,
+  setCellAt,
+  StylePool,
+} from './screen.ts'
+
+function collectStdout(diff: ReturnType<LogUpdate['render']>): string {
+  return diff
+    .filter((patch): patch is Extract<(typeof diff)[number], { type: 'stdout' }> => patch.type === 'stdout')
+    .map(patch => patch.content)
+    .join('')
+}
+
+function createHarness() {
+  const stylePool = new StylePool()
+  const charPool = new CharPool()
+  const hyperlinkPool = new HyperlinkPool()
+
+  return {
+    stylePool,
+    charPool,
+    hyperlinkPool,
+    log: new LogUpdate({ isTTY: true, stylePool }),
+  }
+}
+
+function frameFromLines(
+  stylePool: StylePool,
+  charPool: CharPool,
+  hyperlinkPool: HyperlinkPool,
+  lines: string[],
+  cursor = { x: 0, y: lines.length, visible: true },
+): Frame {
+  const width = lines.reduce((max, line) => Math.max(max, line.length), 0)
+  const screen = createScreen(width, lines.length, stylePool, charPool, hyperlinkPool)
+
+  for (const [y, line] of lines.entries()) {
+    for (const [x, char] of [...line].entries()) {
+      setCellAt(screen, x, y, {
+        char,
+        styleId: stylePool.none,
+        width: CellWidth.Narrow,
+      })
+    }
+  }
+
+  return {
+    screen,
+    viewport: {
+      width: Math.max(width, 1),
+      height: 10,
+    },
+    cursor,
+  }
+}
+
+test('ghostty main-screen rewrite paints prompt content without full terminal reset when width is stable', () => {
+  const { stylePool, charPool, hyperlinkPool, log } = createHarness()
+  const prev = frameFromLines(stylePool, charPool, hyperlinkPool, ['      '])
+  const next = frameFromLines(stylePool, charPool, hyperlinkPool, ['prompt'])
+
+  const diff = log.render(prev, next, false, true, true)
+  const stdout = collectStdout(diff)
+
+  expect(diff.some(patch => patch.type === 'clearTerminal')).toBe(false)
+  expect(diff.some(patch => patch.type === 'clear' && patch.count === 1)).toBe(
+    true,
+  )
+  expect(stdout).toContain('prompt')
+})
+
+test('ghostty main-screen rewrite clears only the changed prompt tail before repainting', () => {
+  const { stylePool, charPool, hyperlinkPool, log } = createHarness()
+  const prev = frameFromLines(
+    stylePool,
+    charPool,
+    hyperlinkPool,
+    ['status', '> abc'],
+  )
+  const next = frameFromLines(
+    stylePool,
+    charPool,
+    hyperlinkPool,
+    ['status', '> abcd'],
+  )
+
+  const diff = log.render(prev, next, false, true, true)
+  const stdout = collectStdout(diff)
+
+  expect(diff.some(patch => patch.type === 'clearTerminal')).toBe(false)
+  expect(diff.some(patch => patch.type === 'clear' && patch.count === 1)).toBe(
+    true,
+  )
+  expect(stdout).toContain('abcd')
+})
+
+test('ghostty main-screen rewrite falls back to incremental diff for larger changes', () => {
+  const { stylePool, charPool, hyperlinkPool, log } = createHarness()
+  const prev = frameFromLines(
+    stylePool,
+    charPool,
+    hyperlinkPool,
+    ['row 0', 'row 1', 'row 2', 'row 3', 'row 4', '> abc'],
+  )
+  const next = frameFromLines(
+    stylePool,
+    charPool,
+    hyperlinkPool,
+    ['row 0 updated', 'row 1', 'row 2', 'row 3', 'row 4', '> abcd'],
+  )
+
+  const diff = log.render(prev, next, false, true, true)
+  const stdout = collectStdout(diff)
+
+  expect(diff.some(patch => patch.type === 'clear')).toBe(false)
+  expect(stdout).toContain('updated')
+  expect(stdout).toContain('abcd')
+})

src/ink/log-update.ts

@@ -125,6 +125,7 @@ export class LogUpdate {
     next: Frame,
     altScreen = false,
     decstbmSafe = true,
+    rewriteMainScreen = false,
   ): Diff {
     if (!this.options.isTTY) {
       return this.renderFullFrame(next)
@@ -146,6 +147,13 @@ export class LogUpdate {
       return fullResetSequence_CAUSES_FLICKER(next, 'resize', stylePool)
     }
 
+    if (!altScreen && rewriteMainScreen) {
+      const rewriteStartY = findMainScreenRewriteStart(prev.screen, next.screen)
+      if (rewriteStartY !== null) {
+        return rewriteMainScreenFrame(prev, next, stylePool, rewriteStartY)
+      }
+    }
+
     // DECSTBM scroll optimization: when a ScrollBox's scrollTop changed,
     // shift content with a hardware scroll (CSI top;bot r + CSI n S/T)
     // instead of rewriting the whole scroll region. The shiftRows on
@@ -420,34 +428,8 @@ export class LogUpdate {
     // Main screen: if cursor needs to be past the last line of content
     // (typical: cursor.y = screen.height), emit \n to create that line
     // since cursor movement can't create new lines.
-    if (altScreen) {
-      // no-op; next frame's CSI H anchors cursor
-    } else if (next.cursor.y >= next.screen.height) {
-      // Move to column 0 of current line, then emit newlines to reach target row
-      screen.txn(prev => {
-        const rowsToCreate = next.cursor.y - prev.y
-        if (rowsToCreate > 0) {
-          // Use CR to resolve pending wrap (if any) without advancing
-          // to the next line, then LF to create each new row.
-          const patches: Diff = new Array<Diff[number]>(1 + rowsToCreate)
-          patches[0] = CARRIAGE_RETURN
-          for (let i = 0; i < rowsToCreate; i++) {
-            patches[1 + i] = NEWLINE
-          }
-          return [patches, { dx: -prev.x, dy: rowsToCreate }]
-        }
-        // At or past target row - need to move cursor to correct position
-        const dy = next.cursor.y - prev.y
-        if (dy !== 0 || prev.x !== next.cursor.x) {
-          // Use CR to clear pending wrap (if any), then cursor move
-          const patches: Diff = [CARRIAGE_RETURN]
-          patches.push({ type: 'cursorMove', x: next.cursor.x, y: dy })
-          return [patches, { dx: next.cursor.x - prev.x, dy }]
-        }
-        return [[], { dx: 0, dy: 0 }]
-      })
-    } else {
-      moveCursorTo(screen, next.cursor.x, next.cursor.y)
+    if (!altScreen) {
+      restoreMainScreenCursor(screen, next)
     }
 
     const elapsed = performance.now() - startTime
@@ -467,6 +449,77 @@ export class LogUpdate {
   }
 }
 
+function rewriteMainScreenFrame(
+  prev: Frame,
+  next: Frame,
+  stylePool: StylePool,
+  startY: number,
+): Diff {
+  const diff: Diff = []
+  const clearCount = prev.screen.height - startY
+
+  if (clearCount > 0) {
+    const clearStartY = prev.screen.height - 1
+    const clearCursor = new VirtualScreen(prev.cursor, next.viewport.width)
+    moveCursorTo(clearCursor, 0, clearStartY)
+    diff.push(...clearCursor.diff)
+    diff.push({ type: 'clear', count: clearCount })
+  }
+
+  const screen = new VirtualScreen(
+    clearCount > 0 ? { x: 0, y: startY } : prev.cursor,
+    next.viewport.width,
+  )
+  renderFrameSlice(screen, next, startY, next.screen.height, stylePool)
+  restoreMainScreenCursor(screen, next)
+
+  return [...diff, ...screen.diff]
+}
+
+const MAX_MAIN_SCREEN_REWRITE_ROWS = 6
+
+function findMainScreenRewriteStart(prev: Screen, next: Screen): number | null {
+  const commonHeight = Math.min(prev.height, next.height)
+  let firstChangedY = commonHeight
+
+  for (let y = 0; y < commonHeight; y += 1) {
+    if (!rowsEqual(prev, next, y)) {
+      firstChangedY = y
+      break
+    }
+  }
+
+  const rewriteRows = Math.max(prev.height, next.height) - firstChangedY
+  if (rewriteRows <= 0) {
+    return null
+  }
+
+  return rewriteRows <= MAX_MAIN_SCREEN_REWRITE_ROWS ? firstChangedY : null
+}
+
+function rowsEqual(prev: Screen, next: Screen, y: number): boolean {
+  if (prev.width !== next.width) {
+    return false
+  }
+
+  if (prev.softWrap[y] !== next.softWrap[y]) {
+    return false
+  }
+
+  const rowStart = y * prev.width
+  const rowEnd = rowStart + prev.width
+  for (let index = rowStart; index < rowEnd; index += 1) {
+    if (
+      prev.cells64[index] !== next.cells64[index] ||
+      prev.noSelect[index] !== next.noSelect[index]
+    ) {
+      return false
+    }
+  }
+
+  return true
+}
+
 function transitionHyperlink(
   diff: Diff,
   current: Hyperlink,
@@ -622,6 +675,37 @@ function renderFrameSlice(
   return screen
 }
 
+function restoreMainScreenCursor(screen: VirtualScreen, next: Frame): void {
+  if (next.cursor.y >= next.screen.height) {
+    // Move to column 0 of current line, then emit newlines to reach target row
+    screen.txn(prev => {
+      const rowsToCreate = next.cursor.y - prev.y
+      if (rowsToCreate > 0) {
+        // Use CR to resolve pending wrap (if any) without advancing
+        // to the next line, then LF to create each new row.
+        const patches: Diff = new Array<Diff[number]>(1 + rowsToCreate)
+        patches[0] = CARRIAGE_RETURN
+        for (let i = 0; i < rowsToCreate; i++) {
+          patches[1 + i] = NEWLINE
+        }
+        return [patches, { dx: -prev.x, dy: rowsToCreate }]
+      }
+      // At or past target row - need to move cursor to correct position
+      const dy = next.cursor.y - prev.y
+      if (dy !== 0 || prev.x !== next.cursor.x) {
+        // Use CR to clear pending wrap (if any), then cursor move
+        const patches: Diff = [CARRIAGE_RETURN]
+        patches.push({ type: 'cursorMove', x: next.cursor.x, y: dy })
+        return [patches, { dx: next.cursor.x - prev.x, dy }]
+      }
+      return [[], { dx: 0, dy: 0 }]
+    })
+    return
+  }
+
+  moveCursorTo(screen, next.cursor.x, next.cursor.y)
+}
+
 type Delta = { dx: number; dy: number }
 
 /**

src/ink/terminal.ts

@@ -135,6 +135,13 @@ export function setXtversionName(name: string): void {
   if (xtversionName === undefined) xtversionName = name
 }
 
+export function isGhosttyTerminal(): boolean {
+  if (process.env.NODE_ENV === 'test') return false
+  if (process.env.TERM_PROGRAM === 'ghostty') return true
+  if (process.env.TERM === 'xterm-ghostty') return true
+  return xtversionName?.toLowerCase().startsWith('ghostty') ?? false
+}
+
 /** True if running in an xterm.js-based terminal (VS Code, Cursor, Windsurf
  *  integrated terminals). Combines TERM_PROGRAM env check (fast, sync, but
  *  not forwarded over SSH) with the XTVERSION probe result (async, survives
@@ -145,6 +152,20 @@ export function isXtermJs(): boolean {
   return xtversionName?.startsWith('xterm.js') ?? false
 }
 
+/** Ghostty currently repaints main-screen prompt updates more reliably
+ *  without DEC 2026 synchronized output. Prefer explicit terminal identity
+ *  (TERM_PROGRAM/TERM or XTVERSION) in real sessions, but keep tests
+ *  deterministic by disabling the env-based detection under NODE_ENV=test. */
+export function shouldSkipMainScreenSyncMarkers(): boolean {
+  return isGhosttyTerminal()
+}
+
+/** Ghostty's main-screen prompt updates are currently more reliable when we
+ *  bypass the incremental diff path and rewrite the visible prompt block. */
+export function shouldUseMainScreenRewrite(): boolean {
+  return isGhosttyTerminal()
+}
+
 // Terminals known to correctly implement the Kitty keyboard protocol
 // (CSI >1u) and/or xterm modifyOtherKeys (CSI >4;2m) for ctrl+shift+<letter>
 // disambiguation. We previously enabled unconditionally (#23350), assuming