perf(terminal): add output flow control / back-pressure for heavy streams (#1090)

fetchSuggestions ran the full completion pipeline (history scan, fig specs, remote path lookups) on the main thread even when both the popup and ghost text were disabled — the results were then discarded. Add a shouldQueryCompletions(settings) gate and bail out early (clearing any stale state) when neither display mode is on.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

application/i18n/locales/en.ts

@@ -301,6 +301,9 @@ const en: Messages = {
   'settings.terminal.keyboard.altAsMeta': 'Use Option as Meta key',
   'settings.terminal.keyboard.altAsMeta.desc':
     'Use Option (Alt) as the Meta key instead of for special characters',
+  'settings.terminal.keyboard.optionArrowWordJump': 'Option+←/→ jumps by word',
+  'settings.terminal.keyboard.optionArrowWordJump.desc':
+    'Send Meta-b / Meta-f on Option+Left/Right so the shell moves by word, instead of the default ^[[1;3D / ^[[1;3C',
   'settings.terminal.accessibility.minimumContrastRatio': 'Minimum contrast ratio',
   'settings.terminal.accessibility.minimumContrastRatio.desc':
     'Adjust colors to meet contrast requirements (1 = disabled, 21 = max)',
@@ -2092,6 +2095,11 @@ const en: Messages = {
   'zmodem.uploading': 'Uploading',
   'zmodem.downloading': 'Downloading',
   'zmodem.cancelTransfer': 'Cancel transfer (Ctrl+C)',
+  'zmodem.overwrite.title': 'Remote file already exists',
+  'zmodem.overwrite.applyToRest': 'Apply to remaining conflicts',
+  'zmodem.overwrite.overwrite': 'Overwrite',
+  'zmodem.overwrite.skip': 'Skip',
+  'zmodem.overwrite.cancel': 'Cancel',
   'settings.shortcuts.resetToDefault': 'Reset to default',
 };
 

application/i18n/locales/ru.ts

@@ -301,6 +301,9 @@ const ru: Messages = {
   'settings.terminal.keyboard.altAsMeta': 'Использовать Option как клавишу Meta',
   'settings.terminal.keyboard.altAsMeta.desc':
     'Использовать Option (Alt) как клавишу Meta вместо ввода специальных символов',
+  'settings.terminal.keyboard.optionArrowWordJump': 'Option+←/→ переход по словам',
+  'settings.terminal.keyboard.optionArrowWordJump.desc':
+    'Отправлять Meta-b / Meta-f при Option+Влево/Вправо, чтобы оболочка перемещалась по словам, вместо стандартного ^[[1;3D / ^[[1;3C',
   'settings.terminal.accessibility.minimumContrastRatio': 'Минимальный коэффициент контрастности',
   'settings.terminal.accessibility.minimumContrastRatio.desc':
     'Подстраивать цвета под требования контрастности (1 = отключено, 21 = максимум)',
@@ -2124,6 +2127,11 @@ const ru: Messages = {
   'zmodem.uploading': 'Загрузка',
   'zmodem.downloading': 'Скачивание',
   'zmodem.cancelTransfer': 'Отменить передачу (Ctrl+C)',
+  'zmodem.overwrite.title': 'Remote file already exists',
+  'zmodem.overwrite.applyToRest': 'Apply to remaining conflicts',
+  'zmodem.overwrite.overwrite': 'Overwrite',
+  'zmodem.overwrite.skip': 'Skip',
+  'zmodem.overwrite.cancel': 'Cancel',
   'settings.shortcuts.resetToDefault': 'Сбросить по умолчанию',
 };
 

application/i18n/locales/zh-CN.ts

@@ -1445,6 +1445,8 @@ const zhCN: Messages = {
   'settings.terminal.cursor.blink': '光标闪烁',
   'settings.terminal.keyboard.altAsMeta': '将 Option 作为 Meta 键',
   'settings.terminal.keyboard.altAsMeta.desc': '使用 Option (Alt) 作为 Meta 键，而不是用于输入特殊字符',
+  'settings.terminal.keyboard.optionArrowWordJump': 'Option+←/→ 按单词跳转',
+  'settings.terminal.keyboard.optionArrowWordJump.desc': '按 Option+左/右 时发送 Meta-b / Meta-f，让 Shell 按单词移动光标（而非默认的 ^[[1;3D / ^[[1;3C）',
   'settings.terminal.accessibility.minimumContrastRatio': '最小对比度',
   'settings.terminal.accessibility.minimumContrastRatio.desc': '调整颜色以满足对比度要求 (1 = 禁用, 21 = 最大)',
   'settings.terminal.behavior.rightClick': '右键行为',
@@ -2101,6 +2103,11 @@ const zhCN: Messages = {
   'zmodem.uploading': '上传中',
   'zmodem.downloading': '下载中',
   'zmodem.cancelTransfer': '取消传输 (Ctrl+C)',
+  'zmodem.overwrite.title': '远端已存在同名文件',
+  'zmodem.overwrite.applyToRest': '应用到其余冲突文件',
+  'zmodem.overwrite.overwrite': '覆盖',
+  'zmodem.overwrite.skip': '跳过',
+  'zmodem.overwrite.cancel': '取消',
   'settings.shortcuts.resetToDefault': '重置为默认',
 };
 

application/state/autoSyncRemoteSchedule.test.ts

@@ -0,0 +1,111 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+
+import {
+  getRuntimeRemoteCheckIntervalMs,
+  shouldRunRuntimeRemoteCheck,
+} from './autoSyncRemoteSchedule';
+
+test("runtime remote checks wait for the startup check to finish", () => {
+  assert.equal(
+    shouldRunRuntimeRemoteCheck({
+      hasAnyConnectedProvider: true,
+      autoSyncEnabled: true,
+      isUnlocked: true,
+      startupRemoteCheckDone: false,
+      isSyncing: false,
+      isSyncRunning: false,
+      remoteCheckInFlight: false,
+      now: 10_000,
+      lastRemoteCheckAt: null,
+      minIntervalMs: 30_000,
+    }),
+    false,
+  );
+});
+
+test("runtime remote checks run immediately after startup gate opens", () => {
+  assert.equal(
+    shouldRunRuntimeRemoteCheck({
+      hasAnyConnectedProvider: true,
+      autoSyncEnabled: true,
+      isUnlocked: true,
+      startupRemoteCheckDone: true,
+      isSyncing: false,
+      isSyncRunning: false,
+      remoteCheckInFlight: false,
+      now: 10_000,
+      lastRemoteCheckAt: null,
+      minIntervalMs: 30_000,
+    }),
+    true,
+  );
+});
+
+test("runtime remote checks respect the minimum interval", () => {
+  const common = {
+    hasAnyConnectedProvider: true,
+    autoSyncEnabled: true,
+    isUnlocked: true,
+    startupRemoteCheckDone: true,
+    isSyncing: false,
+    isSyncRunning: false,
+    remoteCheckInFlight: false,
+    minIntervalMs: 30_000,
+  };
+
+  assert.equal(
+    shouldRunRuntimeRemoteCheck({
+      ...common,
+      now: 35_000,
+      lastRemoteCheckAt: 10_000,
+    }),
+    false,
+  );
+  assert.equal(
+    shouldRunRuntimeRemoteCheck({
+      ...common,
+      now: 40_000,
+      lastRemoteCheckAt: 10_000,
+    }),
+    true,
+  );
+});
+
+test("forced runtime remote checks bypass only the interval gate", () => {
+  const common = {
+    hasAnyConnectedProvider: true,
+    autoSyncEnabled: true,
+    isUnlocked: true,
+    startupRemoteCheckDone: true,
+    isSyncing: false,
+    isSyncRunning: false,
+    remoteCheckInFlight: false,
+    minIntervalMs: 30_000,
+    force: true,
+  };
+
+  assert.equal(
+    shouldRunRuntimeRemoteCheck({
+      ...common,
+      now: 35_000,
+      lastRemoteCheckAt: 10_000,
+    }),
+    true,
+  );
+  assert.equal(
+    shouldRunRuntimeRemoteCheck({
+      ...common,
+      isSyncing: true,
+      now: 35_000,
+      lastRemoteCheckAt: 10_000,
+    }),
+    false,
+  );
+});
+
+test("configured auto-sync intervals map to bounded remote recheck intervals", () => {
+  assert.equal(getRuntimeRemoteCheckIntervalMs(1), 30_000);
+  assert.equal(getRuntimeRemoteCheckIntervalMs(10), 300_000);
+  assert.equal(getRuntimeRemoteCheckIntervalMs(120), 300_000);
+});

application/state/autoSyncRemoteSchedule.ts

@@ -0,0 +1,35 @@
+const MIN_RUNTIME_REMOTE_CHECK_MS = 30_000;
+const MAX_RUNTIME_REMOTE_CHECK_MS = 5 * 60_000;
+
+export function getRuntimeRemoteCheckIntervalMs(autoSyncIntervalMinutes: number): number {
+  const configuredMs = Math.max(1, Number(autoSyncIntervalMinutes) || 1) * 60_000;
+  return Math.max(
+    MIN_RUNTIME_REMOTE_CHECK_MS,
+    Math.min(MAX_RUNTIME_REMOTE_CHECK_MS, Math.floor(configuredMs / 2)),
+  );
+}
+
+export interface RuntimeRemoteCheckInput {
+  hasAnyConnectedProvider: boolean;
+  autoSyncEnabled: boolean;
+  isUnlocked: boolean;
+  startupRemoteCheckDone: boolean;
+  isSyncing: boolean;
+  isSyncRunning: boolean;
+  remoteCheckInFlight: boolean;
+  force?: boolean;
+  now: number;
+  lastRemoteCheckAt: number | null;
+  minIntervalMs: number;
+}
+
+export function shouldRunRuntimeRemoteCheck(input: RuntimeRemoteCheckInput): boolean {
+  if (!input.hasAnyConnectedProvider) return false;
+  if (!input.autoSyncEnabled) return false;
+  if (!input.isUnlocked) return false;
+  if (!input.startupRemoteCheckDone) return false;
+  if (input.isSyncing || input.isSyncRunning || input.remoteCheckInFlight) return false;
+  if (input.force === true) return true;
+  if (input.lastRemoteCheckAt == null) return true;
+  return input.now - input.lastRemoteCheckAt >= input.minIntervalMs;
+}

application/state/resolveTerminalSessionExitIntent.test.ts

@@ -3,10 +3,10 @@ import assert from "node:assert/strict";
 
 import { resolveTerminalSessionExitIntent } from "./resolveTerminalSessionExitIntent.ts";
 
-test("backend exited events keep the tab and mark it disconnected", () => {
+test("normal backend exited events close the session tab", () => {
   assert.deepEqual(
     resolveTerminalSessionExitIntent({ reason: "exited", exitCode: 0 }),
-    { kind: "markDisconnected" },
+    { kind: "closeSession" },
   );
 });
 
@@ -16,3 +16,17 @@ test("backend timeout events keep the tab and mark it disconnected", () => {
     { kind: "markDisconnected" },
   );
 });
+
+test("backend error events keep the tab and mark it disconnected", () => {
+  assert.deepEqual(
+    resolveTerminalSessionExitIntent({ reason: "error", error: "connection reset" }),
+    { kind: "markDisconnected" },
+  );
+});
+
+test("backend closed events keep the tab and mark it disconnected", () => {
+  assert.deepEqual(
+    resolveTerminalSessionExitIntent({ reason: "closed", exitCode: 0 }),
+    { kind: "markDisconnected" },
+  );
+});

application/state/resolveTerminalSessionExitIntent.ts

@@ -6,12 +6,17 @@ export type TerminalSessionExitEvent = {
 };
 
 export type TerminalSessionExitIntent =
+  | { kind: "closeSession" }
   | { kind: "markDisconnected" };
 
 export function resolveTerminalSessionExitIntent(
-  _evt: TerminalSessionExitEvent,
+  evt: TerminalSessionExitEvent,
 ): TerminalSessionExitIntent {
-  // Backend exits can be remote idle timeouts, shell termination, or transport closes.
-  // Explicit user closes bypass this policy and call the close-session path directly.
+  if (evt.reason === "exited") {
+    return { kind: "closeSession" };
+  }
+
+  // Timeouts, transport errors, and channel closes should keep the tab visible
+  // so the user can inspect output and reconnect.
   return { kind: "markDisconnected" };
 }

application/state/useAutoSync.ts

@@ -16,6 +16,7 @@ import {
   findSyncPayloadEncryptedCredentialPaths,
 } from '../../domain/credentials';
 import { isProviderReadyForSync, type CloudProvider, type SyncPayload } from '../../domain/sync';
+import { mergeSyncPayloads } from '../../domain/syncMerge';
 import {
   SYNCABLE_SETTING_STORAGE_KEYS,
   collectSyncableSettings,
@@ -31,6 +32,10 @@ import {
   localStorageAdapter,
 } from '../../infrastructure/persistence/localStorageAdapter';
 import { notify } from '../notification';
+import {
+  getRuntimeRemoteCheckIntervalMs,
+  shouldRunRuntimeRemoteCheck,
+} from './autoSyncRemoteSchedule';
 
 interface AutoSyncConfig {
   // Data to sync
@@ -95,6 +100,11 @@ interface SyncNowOptions {
   trigger?: SyncTrigger;
 }
 
+interface RemoteVersionCheckOptions {
+  force?: boolean;
+  notifyOnFailure?: boolean;
+}
+
 export const useAutoSync = (config: AutoSyncConfig) => {
   const { t } = useI18n();
   const sync = useCloudSync();
@@ -402,17 +412,20 @@ export const useAutoSync = (config: AutoSyncConfig) => {
   // windows but does NOT serialize same-window re-entry, so this
   // in-flight guard closes that gap at the top of the call.
   const checkRemoteInFlightRef = useRef(false);
+  const lastRuntimeRemoteCheckAtRef = useRef<number | null>(null);
 
   // Check remote version and pull if newer (on startup)
-  const checkRemoteVersion = useCallback(async () => {
+  const checkRemoteVersion = useCallback(async (options?: RemoteVersionCheckOptions) => {
     if (checkRemoteInFlightRef.current) {
       return;
     }
+    const force = options?.force === true;
+    const notifyOnFailure = options?.notifyOnFailure !== false;
     const state = manager.getState();
     const hasProvider = Object.values(state.providers).some((provider) => isProviderReadyForSync(provider));
     const unlocked = state.securityState === 'UNLOCKED';
 
-    if (!hasProvider || !unlocked || hasCheckedRemoteRef.current || startupReadyRef.current === false) {
+    if (!hasProvider || !unlocked || (!force && hasCheckedRemoteRef.current) || startupReadyRef.current === false) {
       return;
     }
 
@@ -494,7 +507,6 @@ export const useAutoSync = (config: AutoSyncConfig) => {
         return;
       }
 
-      const { mergeSyncPayloads } = await import('../../domain/syncMerge');
       const mergeResult = mergeSyncPayloads(base, localPayload, remotePayload);
 
       // Apply merged payload to local state BEFORE committing. If the apply
@@ -548,14 +560,16 @@ export const useAutoSync = (config: AutoSyncConfig) => {
       }
     } catch (error) {
       console.error('[AutoSync] Failed to check remote version:', error);
-      // Surface a degraded-sync hint to the user rather than silently
-      // opening the auto-sync gate. Auto-sync will still retry on next
-      // data change (see finally block), but without this toast the user
-      // has no visible signal that startup reconciliation failed.
-      notify.error(
-        t('sync.autoSync.inspectFailedMessage'),
-        t('sync.autoSync.inspectFailedTitle'),
-      );
+      if (notifyOnFailure) {
+        // Surface a degraded-sync hint to the user rather than silently
+        // opening the auto-sync gate. Auto-sync will still retry on next
+        // data change (see finally block), but without this toast the user
+        // has no visible signal that startup reconciliation failed.
+        notify.error(
+          t('sync.autoSync.inspectFailedMessage'),
+          t('sync.autoSync.inspectFailedTitle'),
+        );
+      }
       // Leave hasCheckedRemoteRef=false so the next startup (or the next
       // provider/unlock transition) can retry.
     } finally {
@@ -726,12 +740,86 @@ export const useAutoSync = (config: AutoSyncConfig) => {
       if (timerId) clearTimeout(timerId);
     };
   }, [sync.hasAnyConnectedProvider, sync.isUnlocked, config.startupReady, checkRemoteVersion]);
+
+  const runRuntimeRemoteCheck = useCallback(async (options?: { force?: boolean }) => {
+    const now = Date.now();
+    const minIntervalMs = getRuntimeRemoteCheckIntervalMs(sync.autoSyncInterval);
+    if (!shouldRunRuntimeRemoteCheck({
+      hasAnyConnectedProvider: sync.hasAnyConnectedProvider,
+      autoSyncEnabled: sync.autoSyncEnabled,
+      isUnlocked: sync.isUnlocked,
+      startupRemoteCheckDone: remoteCheckDoneRef.current,
+      isSyncing: sync.isSyncing,
+      isSyncRunning: isSyncRunningRef.current,
+      remoteCheckInFlight: checkRemoteInFlightRef.current,
+      force: options?.force === true,
+      now,
+      lastRemoteCheckAt: lastRuntimeRemoteCheckAtRef.current,
+      minIntervalMs,
+    })) {
+      return;
+    }
+
+    lastRuntimeRemoteCheckAtRef.current = now;
+    await checkRemoteVersion({ force: true, notifyOnFailure: false });
+  }, [
+    checkRemoteVersion,
+    sync.autoSyncEnabled,
+    sync.autoSyncInterval,
+    sync.hasAnyConnectedProvider,
+    sync.isSyncing,
+    sync.isUnlocked,
+  ]);
+
+  // Keep checking the cloud while the app is open. This closes the gap where
+  // another device uploads changes after our startup inspection but before
+  // this device edits anything locally.
+  useEffect(() => {
+    if (!sync.hasAnyConnectedProvider || !sync.autoSyncEnabled || !sync.isUnlocked) {
+      return;
+    }
+
+    const intervalMs = getRuntimeRemoteCheckIntervalMs(sync.autoSyncInterval);
+    const timerId = window.setInterval(() => {
+      void runRuntimeRemoteCheck();
+    }, intervalMs);
+
+    return () => window.clearInterval(timerId);
+  }, [
+    runRuntimeRemoteCheck,
+    sync.autoSyncEnabled,
+    sync.autoSyncInterval,
+    sync.hasAnyConnectedProvider,
+    sync.isUnlocked,
+  ]);
+
+  // Also re-check when the user returns to the app or the network comes back.
+  useEffect(() => {
+    if (typeof window === 'undefined' || typeof document === 'undefined') return;
+
+    const handleVisibilityChange = () => {
+      if (document.visibilityState === 'visible') {
+        void runRuntimeRemoteCheck({ force: true });
+      }
+    };
+    const handleOnline = () => {
+      void runRuntimeRemoteCheck({ force: true });
+    };
+
+    document.addEventListener('visibilitychange', handleVisibilityChange);
+    window.addEventListener('online', handleOnline);
+    return () => {
+      document.removeEventListener('visibilitychange', handleVisibilityChange);
+      window.removeEventListener('online', handleOnline);
+    };
+  }, [runRuntimeRemoteCheck]);
   
   // Reset check flags when provider disconnects
   useEffect(() => {
     if (!sync.hasAnyConnectedProvider) {
       hasCheckedRemoteRef.current = false;
       remoteCheckDoneRef.current = false;
+      lastRuntimeRemoteCheckAtRef.current = null;
     }
   }, [sync.hasAnyConnectedProvider]);
 

application/state/useTerminalBackend.ts

@@ -73,6 +73,11 @@ export const useTerminalBackend = () => {
     bridge?.resizeSession?.(sessionId, cols, rows);
   }, []);
 
+  const setSessionFlowPaused = useCallback((sessionId: string, paused: boolean) => {
+    const bridge = netcattyBridge.get();
+    bridge?.setSessionFlowPaused?.(sessionId, paused);
+  }, []);
+
   const closeSession = useCallback((sessionId: string) => {
     const bridge = netcattyBridge.get();
     bridge?.closeSession?.(sessionId);
@@ -208,6 +213,7 @@ export const useTerminalBackend = () => {
       getServerStats,
       writeToSession,
       resizeSession,
+      setSessionFlowPaused,
       closeSession,
       setSessionEncoding,
       onSessionData,
@@ -240,6 +246,7 @@ export const useTerminalBackend = () => {
       getServerStats,
       writeToSession,
       resizeSession,
+      setSessionFlowPaused,
       closeSession,
       setSessionEncoding,
       onSessionData,

application/syncPayload.ts

@@ -164,7 +164,7 @@ const SYNCABLE_TERMINAL_KEYS = [
   'scrollback', 'drawBoldInBrightColors', 'terminalEmulationType',
   'fontLigatures', 'fontWeight', 'fontWeightBold', 'fallbackFont',
   'linePadding', 'cursorShape', 'cursorBlink', 'minimumContrastRatio',
-  'altAsMeta', 'scrollOnInput', 'scrollOnOutput', 'scrollOnKeyPress', 'scrollOnPaste',
+  'altAsMeta', 'optionArrowWordJump', 'scrollOnInput', 'scrollOnOutput', 'scrollOnKeyPress', 'scrollOnPaste',
   'smoothScrolling',
   'rightClickBehavior', 'copyOnSelect', 'middleClickPaste', 'wordSeparators',
   'linkModifier', 'keywordHighlightEnabled', 'keywordHighlightRules',

components/Terminal.tsx

@@ -5,7 +5,6 @@ import { SearchAddon } from "@xterm/addon-search";
 import "@xterm/xterm/css/xterm.css";
 import { Cpu, Copy, HardDrive, Maximize2, MemoryStick, Radio, ArrowDownToLine, ArrowUpFromLine } from "lucide-react";
 import React, { memo, useCallback, useEffect, useLayoutEffect, useMemo, useRef, useState } from "react";
-import ReactDOM from "react-dom";
 import { useI18n } from "../application/i18n/I18nProvider";
 import { logger } from "../lib/logger";
 import { cn, normalizeLineEndings, wrapBracketedPaste } from "../lib/utils";
@@ -29,7 +28,7 @@ import {
   applyCustomAccentToTerminalTheme,
   resolveHostTerminalThemeId,
 } from "../domain/terminalAppearance";
-import { classifyDistroId } from "../domain/host";
+import { classifyDistroId, shouldProbeSessionCwd } from "../domain/host";
 import { resolveHostAuth } from "../domain/sshAuth";
 import { useTerminalBackend } from "../application/state/useTerminalBackend";
 // SFTPModal removed - SFTP is now handled by SftpSidePanel in TerminalLayer
@@ -49,12 +48,15 @@ import { TerminalToolbar } from "./terminal/TerminalToolbar";
 import { TerminalComposeBar } from "./terminal/TerminalComposeBar";
 import { TerminalContextMenu } from "./terminal/TerminalContextMenu";
 import { TerminalSearchBar } from "./terminal/TerminalSearchBar";
+import { ZmodemOverwriteDialog } from "./terminal/ZmodemOverwriteDialog";
 import { ZmodemProgressIndicator } from "./terminal/ZmodemProgressIndicator";
 import { createReplaySafeTerminalLogSanitizer } from "./terminal/replaySafeTerminalLog";
+import { createConnectionLogBuffer } from "./terminal/connectionLogBuffer";
 import { useZmodemTransfer } from "./terminal/hooks/useZmodemTransfer";
 import { createTerminalSessionStarters, type PendingAuth } from "./terminal/runtime/createTerminalSessionStarters";
 import { createXTermRuntime, primaryFontFamily, type XTermRuntime } from "./terminal/runtime/createXTermRuntime";
 import { applyUserCursorPreference } from "./terminal/runtime/cursorPreference";
+import { terminalAltKeyOptions } from "./terminal/runtime/altKeyOptions";
 import {
   createPromptLineBreakState,
   type PromptLineBreakState,
@@ -68,7 +70,7 @@ import { useTerminalContextActions } from "./terminal/hooks/useTerminalContextAc
 import { useTerminalAuthState } from "./terminal/hooks/useTerminalAuthState";
 import { useServerStats } from "./terminal/hooks/useServerStats";
 import { extractDropEntries, getPathForFile, DropEntry } from "../lib/sftpFileUtils";
-import { useTerminalAutocomplete, AutocompletePopup } from "./terminal/autocomplete";
+import { TerminalAutocomplete } from "./terminal/TerminalAutocomplete";
 import { createTerminalCwdTracker, resolvePreferredTerminalCwd } from "./terminal/sftpCwd";
 
 const MAX_CONNECTION_LOG_DATA_CHARS = 1_000_000;
@@ -297,7 +299,7 @@ const TerminalComponent: React.FC<TerminalProps> = ({
   // cancelled retry can't fire a startNewSession after the fact.
   const retryTokenRef = useRef<symbol | null>(null);
   const terminalDataCapturedRef = useRef(false);
-  const terminalLogDataRef = useRef("");
+  const connectionLogBufferRef = useRef(createConnectionLogBuffer(MAX_CONNECTION_LOG_DATA_CHARS));
   const terminalLogSanitizerRef = useRef(createReplaySafeTerminalLogSanitizer());
   const onTerminalDataCaptureRef = useRef(onTerminalDataCapture);
   const commandBufferRef = useRef<string>("");
@@ -318,21 +320,15 @@ const TerminalComponent: React.FC<TerminalProps> = ({
   const captureTerminalLogData = useCallback((data: string) => {
     const replaySafeData = terminalLogSanitizerRef.current.append(data);
     if (!replaySafeData) return;
-    terminalLogDataRef.current += replaySafeData;
-    if (terminalLogDataRef.current.length > MAX_CONNECTION_LOG_DATA_CHARS) {
-      terminalLogDataRef.current = terminalLogDataRef.current.slice(-MAX_CONNECTION_LOG_DATA_CHARS);
-    }
+    connectionLogBufferRef.current.append(replaySafeData);
   }, []);
 
   const finalizeTerminalLogData = useCallback(() => {
     const replaySafeData = terminalLogSanitizerRef.current.finish();
     if (replaySafeData) {
-      terminalLogDataRef.current += replaySafeData;
-      if (terminalLogDataRef.current.length > MAX_CONNECTION_LOG_DATA_CHARS) {
-        terminalLogDataRef.current = terminalLogDataRef.current.slice(-MAX_CONNECTION_LOG_DATA_CHARS);
-      }
+      connectionLogBufferRef.current.append(replaySafeData);
     }
-    return terminalLogDataRef.current;
+    return connectionLogBufferRef.current.toString();
   }, []);
 
   const writeLocalTerminalData = useCallback((data: string) => {
@@ -387,10 +383,13 @@ const TerminalComponent: React.FC<TerminalProps> = ({
   const snippetsRef = useRef(snippets);
   snippetsRef.current = snippets;
 
-  // Autocomplete handler refs (set after hook initialization)
+  // Autocomplete handler refs — populated by <TerminalAutocomplete> so the
+  // xterm runtime (and a few effects here) can drive the hook without making
+  // Terminal re-render on every suggestion update.
   const autocompleteKeyEventRef = useRef<((e: KeyboardEvent) => boolean) | undefined>(undefined);
   const autocompleteInputRef = useRef<((data: string) => void) | undefined>(undefined);
   const autocompleteRepositionRef = useRef<(() => void) | undefined>(undefined);
+  const autocompleteCloseRef = useRef<(() => void) | undefined>(undefined);
 
   const terminalBackend = useTerminalBackend();
   const { resizeSession, setSessionEncoding } = terminalBackend;
@@ -539,31 +538,19 @@ const TerminalComponent: React.FC<TerminalProps> = ({
     }
   };
 
-  const autocomplete = useTerminalAutocomplete({
-    termRef,
-    sessionId,
-    hostId: host.id,
-    hostOs: host.os || (host.protocol === "local"
-      ? (navigator.platform?.startsWith("Win") ? "windows" : navigator.platform?.startsWith("Mac") ? "macos" : "linux")
-      : "linux"),
-    settings: terminalSettings ? {
-      enabled: terminalSettings.autocompleteEnabled ?? true,
-      showGhostText: terminalSettings.autocompleteGhostText ?? true,
-      showPopupMenu: terminalSettings.autocompletePopupMenu ?? true,
-      debounceMs: terminalSettings.autocompleteDebounceMs ?? 100,
-      minChars: terminalSettings.autocompleteMinChars ?? 1,
-      maxSuggestions: terminalSettings.autocompleteMaxSuggestions ?? 8,
-    } : undefined,
-    onAcceptText: (text) => autocompleteAcceptTextRef.current?.(text),
-    protocol: host.protocol,
-    getCwd: () => terminalCwdTracker.getRendererCwd() ?? knownCwdRef.current,
-  });
-
-  // Wire up autocomplete handler refs so createXTermRuntime can use them
-  autocompleteKeyEventRef.current = autocomplete.handleKeyEvent;
-  autocompleteInputRef.current = autocomplete.handleInput;
-  autocompleteRepositionRef.current = autocomplete.repositionPopup;
-  const autocompleteClosePopup = autocomplete.closePopup;
+  // Autocomplete config — the hook itself lives in <TerminalAutocomplete> so
+  // its state updates don't re-render this component (see render below).
+  const autocompleteHostOs: "linux" | "windows" | "macos" = host.os || (host.protocol === "local"
+    ? (navigator.platform?.startsWith("Win") ? "windows" : navigator.platform?.startsWith("Mac") ? "macos" : "linux")
+    : "linux");
+  const autocompleteSettings = terminalSettings ? {
+    enabled: terminalSettings.autocompleteEnabled ?? true,
+    showGhostText: terminalSettings.autocompleteGhostText ?? true,
+    showPopupMenu: terminalSettings.autocompletePopupMenu ?? true,
+    debounceMs: terminalSettings.autocompleteDebounceMs ?? 100,
+    minChars: terminalSettings.autocompleteMinChars ?? 1,
+    maxSuggestions: terminalSettings.autocompleteMaxSuggestions ?? 8,
+  } : undefined;
 
   const resolveSftpInitialPath = useCallback(async (): Promise<string | undefined> => {
     const cwd = await resolvePreferredTerminalCwd({
@@ -585,6 +572,21 @@ const TerminalComponent: React.FC<TerminalProps> = ({
     return clearTerminalCwd;
   }, [clearTerminalCwd, host.id]);
 
+  // Classify the host's device family from the *detected* distro and the
+  // explicit deviceType only. This intentionally bypasses
+  // getEffectiveHostDistro(): the manual distro override (`distroMode:
+  // 'manual'` + `manualDistro`) is a purely cosmetic icon choice, and a
+  // user who pinned e.g. an "ubuntu" icon on what is actually a Cisco /
+  // Huawei host must not silently re-enable POSIX-shell probes against it.
+  // Several features gate on this — the working-directory probe below, the
+  // /etc/os-release probe, and the periodic server-stats poll (#674) —
+  // because each opens an extra exec channel that strict network-device
+  // CLIs reject or log as a new AAA session, and on Huawei VRP closes the
+  // whole session (#1043).
+  const detectedDeviceClass = classifyDistroId(host.distro);
+  const isNetworkDevice =
+    host.deviceType === 'network' || detectedDeviceClass === 'network-device';
+
   useEffect(() => {
     if (host.protocol === "local" || host.protocol === "serial" || host.protocol === "telnet") {
       return;
@@ -593,9 +595,20 @@ const TerminalComponent: React.FC<TerminalProps> = ({
 
     let cancelled = false;
     const timer = setTimeout(async () => {
-      if (!sessionRef.current) return;
+      const id = sessionRef.current;
+      if (!id) return;
       try {
-        const result = await terminalBackend.getSessionPwd(sessionRef.current);
+        // The pwd probe opens an extra POSIX-shell exec channel, which strict
+        // network-device CLIs like Huawei VRP answer by closing the whole
+        // session (#1043). Skip it for known network devices; for a brand-new
+        // host (distro not classified yet on the first connect) consult the
+        // SSH banner, which is captured for free at handshake time.
+        const info = await terminalBackend.getSessionRemoteInfo?.(id);
+        if (cancelled || id !== sessionRef.current) return;
+        if (!shouldProbeSessionCwd({ isNetworkDevice, remoteSshVersion: info?.remoteSshVersion })) {
+          return;
+        }
+        const result = await terminalBackend.getSessionPwd(id);
         if (!cancelled && !terminalCwdTracker.getRendererCwd() && result.success && result.cwd) {
           knownCwdRef.current = result.cwd;
         }
@@ -608,37 +621,22 @@ const TerminalComponent: React.FC<TerminalProps> = ({
       cancelled = true;
       clearTimeout(timer);
     };
-  }, [host.protocol, status, terminalBackend, terminalCwdTracker]);
+  }, [host.protocol, status, terminalBackend, terminalCwdTracker, isNetworkDevice]);
 
   useEffect(() => {
     if (!isVisible) {
-      autocompleteClosePopup();
+      autocompleteCloseRef.current?.();
     }
-  }, [isVisible, autocompleteClosePopup]);
+  }, [isVisible]);
 
   // Check if this is a local or serial connection (doesn't need connection dialog during connecting)
   const isLocalConnection = host.protocol === "local";
   const isSerialConnection = host.protocol === "serial";
 
-  // Server stats (CPU, Memory, Disk) — only for Linux/macOS, and never
-  // for hosts classified as network devices (either via explicit
-  // deviceType='network' or via SSH banner detection that populated
-  // host.distro with a network-vendor ID). See #674: polling the stats
-  // command on Cisco / Huawei / Juniper etc. generates one AAA session
-  // log entry per poll because each exec channel is counted as a new
-  // session on those devices.
-  //
-  // IMPORTANT: this gating must NOT go through getEffectiveHostDistro()
-  // because that honors the manual distro override (`distroMode: 'manual'`
-  // + `manualDistro`) which is purely a cosmetic icon choice. A user who
-  // pinned an "ubuntu" icon on what is actually a Cisco host would
-  // otherwise silently re-enable the polling loop and re-introduce the
-  // AAA log flood this patch is meant to eliminate. The display icon can
-  // still be overridden (see DistroAvatar) — gating uses the raw detected
-  // `host.distro` and the explicit `host.deviceType` only.
-  const detectedDeviceClass = classifyDistroId(host.distro);
-  const isNetworkDevice =
-    host.deviceType === 'network' || detectedDeviceClass === 'network-device';
+  // Server stats (CPU, Memory, Disk) — only for Linux/macOS, never for
+  // network devices. See isNetworkDevice above for why the gating uses the
+  // raw detected distro / explicit deviceType (not getEffectiveHostDistro);
+  // #674 covers the AAA-log-flood motivation for stats specifically.
   const isSupportedOs =
     !isNetworkDevice &&
     (host.os === 'linux' || host.os === 'macos' || detectedDeviceClass === 'linux-like');
@@ -927,7 +925,7 @@ const TerminalComponent: React.FC<TerminalProps> = ({
   useEffect(() => {
     let disposed = false;
     terminalDataCapturedRef.current = false;
-    terminalLogDataRef.current = "";
+    connectionLogBufferRef.current.reset();
     terminalLogSanitizerRef.current = createReplaySafeTerminalLogSanitizer();
     setError(null);
     hasConnectedRef.current = false;
@@ -1236,11 +1234,18 @@ const TerminalComponent: React.FC<TerminalProps> = ({
             : 0;
         termRef.current.options.scrollOnUserInput =
           shouldEnableNativeUserInputAutoScroll(terminalSettings);
-        termRef.current.options.altClickMovesCursor = !terminalSettings.altAsMeta;
+        const altKeyOpts = terminalAltKeyOptions(terminalSettings.altAsMeta);
+        termRef.current.options.macOptionIsMeta = altKeyOpts.macOptionIsMeta;
+        termRef.current.options.altClickMovesCursor = altKeyOpts.altClickMovesCursor;
         termRef.current.options.wordSeparator = terminalSettings.wordSeparators;
         termRef.current.options.ignoreBracketedPasteMode = terminalSettings.disableBracketedPaste ?? false;
       }
 
+      // Changing the font can leave the WebGL renderer drawing stale glyphs from
+      // the old metrics (xterm.js #3280), surfacing as garbled text (issue #1049).
+      // Clear the texture atlas so glyphs re-rasterize with the new font.
+      xtermRuntimeRef.current?.clearTextureAtlas();
+
       if (isVisibleRef.current) {
         setTimeout(() => safeFit({ force: true, requireVisible: true }), 50);
       } else {
@@ -1253,6 +1258,18 @@ const TerminalComponent: React.FC<TerminalProps> = ({
     if (!isVisible) return;
     const timer = setTimeout(() => {
       safeFit({ requireVisible: true });
+      // Recover the WebGL renderer now that this tab is visible again. Hidden
+      // panes stay mounted off-screen (visibility:hidden) so each keeps a live
+      // WebGL context; creating another terminal's context — or the GPU dropping
+      // a non-composited off-screen canvas — can leave this terminal's drawing
+      // buffer corrupted ("花屏", issue #1063). Because a hidden pane keeps its
+      // dimensions, becoming visible triggers no resize and therefore no redraw,
+      // so the corruption persists until the user resizes the window. Force the
+      // same recovery a resize performs: clear the texture atlas (no-op on the
+      // DOM renderer) and synchronously repaint every row.
+      xtermRuntimeRef.current?.clearTextureAtlas();
+      const visibleTerm = termRef.current;
+      if (visibleTerm) forceSyncRenderAfterResize(visibleTerm);
       if (pendingOutputScrollRef.current) {
         termRef.current?.scrollToBottom();
         if (typeof requestAnimationFrame === "function") {
@@ -2352,29 +2369,27 @@ const TerminalComponent: React.FC<TerminalProps> = ({
             }}
           />
 
-          {/* Autocomplete popup — rendered via Portal to escape overflow:hidden */}
-          {isVisible && autocomplete.state.popupVisible && autocomplete.state.suggestions.length > 0 &&
-            ReactDOM.createPortal(
-              <AutocompletePopup
-                suggestions={autocomplete.state.suggestions}
-                selectedIndex={autocomplete.state.selectedIndex}
-                position={autocomplete.state.popupPosition}
-                cursorLineTop={autocomplete.state.popupCursorLineTop}
-                cursorLineBottom={autocomplete.state.popupCursorLineBottom}
-                visible={autocomplete.state.popupVisible}
-                expandUpward={autocomplete.state.expandUpward}
-                themeColors={effectiveTheme.colors}
-                onSelect={autocomplete.selectSuggestion}
-                subDirPanels={autocomplete.state.subDirPanels}
-                subDirFocusLevel={autocomplete.state.subDirFocusLevel}
-                containerRef={containerRef}
-                onRequestReposition={autocomplete.repositionPopup}
-                searchBarOffset={isSearchOpen ? 64 : 30}
-                onDismiss={autocompleteClosePopup}
-              />,
-              document.body,
-            )
-          }
+          {/* Autocomplete — owns the hook + popup in its own component so
+              suggestion/selection updates don't re-render Terminal. Mounted
+              unconditionally; it gates the popup on `visible` internally. */}
+          <TerminalAutocomplete
+            termRef={termRef}
+            sessionId={sessionId}
+            hostId={host.id}
+            hostOs={autocompleteHostOs}
+            settings={autocompleteSettings}
+            protocol={host.protocol}
+            getCwd={() => terminalCwdTracker.getRendererCwd() ?? knownCwdRef.current}
+            onAcceptText={(text) => autocompleteAcceptTextRef.current?.(text)}
+            visible={isVisible}
+            themeColors={effectiveTheme.colors}
+            containerRef={containerRef}
+            searchBarOffset={isSearchOpen ? 64 : 30}
+            keyEventRef={autocompleteKeyEventRef}
+            inputRef={autocompleteInputRef}
+            repositionRef={autocompleteRepositionRef}
+            closeRef={autocompleteCloseRef}
+          />
 
           {/* OSC-52 clipboard read prompt */}
           {osc52ReadPromptVisible && (
@@ -2465,6 +2480,13 @@ const TerminalComponent: React.FC<TerminalProps> = ({
               />
             </div>
           )}
+          {/* ZMODEM overwrite conflict dialog */}
+          {zmodem.overwriteRequest && (
+            <ZmodemOverwriteDialog
+              filename={zmodem.overwriteRequest.filename}
+              onRespond={zmodem.respondOverwrite}
+            />
+          )}
         </div>
 
         {/* Compose Bar (solo sessions only; workspace uses TerminalLayer's global bar) */}

components/TerminalLayer.tsx

@@ -978,10 +978,12 @@ const TerminalLayerInner: React.FC<TerminalLayerProps> = ({
 
   const handleSessionExit = useCallback((sessionId: string, evt: TerminalSessionExitEvent) => {
     const intent = resolveTerminalSessionExitIntent(evt);
-    if (intent.kind === "markDisconnected") {
+    if (intent.kind === "closeSession") {
+      onCloseSession(sessionId);
+    } else {
       onUpdateSessionStatus(sessionId, 'disconnected');
     }
-  }, [onUpdateSessionStatus]);
+  }, [onCloseSession, onUpdateSessionStatus]);
 
   const handleOsDetected = useCallback((hostId: string, distro: string) => {
     onUpdateHostDistro(hostId, distro);

components/TopTabs.tsx

@@ -12,6 +12,7 @@ import { cn } from '../lib/utils';
 import { Host, TerminalSession, Workspace } from '../types';
 import { DISTRO_LOGOS, DISTRO_COLORS } from './DistroAvatar';
 import { getShellIconPath, isMonochromeShellIcon } from '../lib/useDiscoveredShells';
+import { handleTabMiddleClickClose, handleTabMiddleMouseDown } from '../lib/tabInteractions';
 import { Button } from './ui/button';
 import { ContextMenu, ContextMenuContent, ContextMenuItem, ContextMenuSeparator, ContextMenuTrigger } from './ui/context-menu';
 import { Tooltip, TooltipContent, TooltipTrigger } from './ui/tooltip';
@@ -355,6 +356,8 @@ const EditorTopTab: React.FC<EditorTopTabProps> = memo(({
           data-tab-type="editor"
           data-state={isActive ? 'active' : 'inactive'}
           onClick={handleClick}
+          onMouseDown={handleTabMiddleMouseDown}
+          onAuxClick={(e) => handleTabMiddleClickClose(e, () => onRequestCloseEditorTab(editorTab.id))}
           className="netcatty-tab relative h-7 pl-3 pr-2 min-w-[140px] max-w-[240px] rounded-t-md overflow-hidden text-xs font-semibold cursor-pointer flex items-center justify-between gap-2 app-no-drag flex-shrink-0"
           style={{
             backgroundColor: isActive
@@ -458,6 +461,8 @@ const SessionTopTab: React.FC<SessionTopTabProps> = memo(({
           data-tab-type="session"
           data-state={isActive ? 'active' : 'inactive'}
           onClick={handleClick}
+          onMouseDown={handleTabMiddleMouseDown}
+          onAuxClick={(e) => handleTabMiddleClickClose(e, () => onCloseSession(session.id))}
           draggable
           onDragStart={(e) => onTabDragStart(e, session.id)}
           onDragEnd={onTabDragEnd}
@@ -586,6 +591,8 @@ const WorkspaceTopTab: React.FC<WorkspaceTopTabProps> = memo(({
           data-tab-type="workspace"
           data-state={isActive ? 'active' : 'inactive'}
           onClick={handleClick}
+          onMouseDown={handleTabMiddleMouseDown}
+          onAuxClick={(e) => handleTabMiddleClickClose(e, () => onCloseWorkspace(workspace.id))}
           draggable
           onDragStart={(e) => onTabDragStart(e, workspace.id)}
           onDragEnd={onTabDragEnd}
@@ -694,6 +701,8 @@ const LogViewTopTab: React.FC<LogViewTopTabProps> = memo(({
       data-tab-type="logView"
       data-state={isActive ? 'active' : 'inactive'}
       onClick={handleClick}
+      onMouseDown={handleTabMiddleMouseDown}
+      onAuxClick={(e) => handleTabMiddleClickClose(e, () => onCloseLogView(logView.id))}
       className="netcatty-tab relative h-7 pl-3 pr-2 min-w-[140px] max-w-[240px] rounded-t-md overflow-hidden text-xs font-semibold cursor-pointer flex items-center justify-between gap-2 app-no-drag flex-shrink-0"
       style={{
         backgroundColor: isActive

components/settings/tabs/SettingsTerminalTab.tsx

@@ -810,6 +810,12 @@ export default function SettingsTerminalTab(props: {
         >
           <Toggle checked={terminalSettings.altAsMeta} onChange={(v) => updateTerminalSetting("altAsMeta", v)} />
         </SettingRow>
+        <SettingRow
+          label={t("settings.terminal.keyboard.optionArrowWordJump")}
+          description={t("settings.terminal.keyboard.optionArrowWordJump.desc")}
+        >
+          <Toggle checked={terminalSettings.optionArrowWordJump} onChange={(v) => updateTerminalSetting("optionArrowWordJump", v)} />
+        </SettingRow>
       </div>
 
       <SectionHeader title={t("settings.terminal.section.accessibility")} />

components/sftp/SftpTabBar.tsx

@@ -20,6 +20,7 @@ import React, {
 } from "react";
 import { useI18n } from "../../application/i18n/I18nProvider";
 import { logger } from "../../lib/logger";
+import { handleTabMiddleClickClose, handleTabMiddleMouseDown } from "../../lib/tabInteractions";
 import { useRenderTracker } from "../../lib/useRenderTracker";
 import { Tooltip, TooltipContent, TooltipTrigger } from "../ui/tooltip";
 import { cn } from "../../lib/utils";
@@ -322,6 +323,8 @@ const SftpTabBarInner: React.FC<SftpTabBarProps> = ({
                 data-tab-type="sftp"
                 data-state={isActive ? 'active' : 'inactive'}
                 onClick={(e) => handleSelectTabClick(e, tab.id)}
+                onMouseDown={handleTabMiddleMouseDown}
+                onAuxClick={(e) => handleTabMiddleClickClose(e, () => onCloseTab(tab.id))}
                 draggable
                 onDragStart={(e) => handleTabDragStart(e, tab.id)}
                 onDragEnd={handleTabDragEnd}

components/terminal/TerminalAutocomplete.tsx

@@ -0,0 +1,111 @@
+import ReactDOM from "react-dom";
+import type { ComponentProps, RefObject } from "react";
+import type { Terminal as XTerm } from "@xterm/xterm";
+import {
+  useTerminalAutocomplete,
+  AutocompletePopup,
+  type AutocompleteSettings,
+} from "./autocomplete";
+
+type PopupProps = ComponentProps<typeof AutocompletePopup>;
+
+/** A mutable handler ref Terminal hands down for the xterm runtime to call. */
+type HandlerRef<T> = { current: T | undefined };
+
+interface TerminalAutocompleteProps {
+  termRef: RefObject<XTerm | null>;
+  sessionId: string;
+  hostId: string;
+  hostOs: "linux" | "windows" | "macos";
+  settings?: Partial<AutocompleteSettings>;
+  protocol?: string;
+  getCwd?: () => string | undefined;
+  onAcceptText: (text: string) => void;
+  /** Whether this terminal tab is the visible one. */
+  visible: boolean;
+  themeColors: PopupProps["themeColors"];
+  containerRef: PopupProps["containerRef"];
+  searchBarOffset: number;
+  // Handlers exposed back to Terminal so createXTermRuntime can drive them.
+  keyEventRef: HandlerRef<(e: KeyboardEvent) => boolean>;
+  inputRef: HandlerRef<(data: string) => void>;
+  repositionRef: HandlerRef<() => void>;
+  closeRef: HandlerRef<() => void>;
+}
+
+/**
+ * Owns the terminal autocomplete hook and renders its popup.
+ *
+ * Kept as its own component so the frequent autocomplete state updates
+ * (suggestions, selection, live-preview navigation) re-render only this small
+ * subtree rather than the whole Terminal component. The hook's handlers are
+ * surfaced back to Terminal through refs so the xterm runtime can call them.
+ *
+ * Must be mounted unconditionally for the terminal session's lifetime: the hook
+ * records command history on Enter and intercepts completion keys even while no
+ * popup is visible. Visibility only gates the rendered popup, not the hook.
+ */
+export function TerminalAutocomplete({
+  termRef,
+  sessionId,
+  hostId,
+  hostOs,
+  settings,
+  protocol,
+  getCwd,
+  onAcceptText,
+  visible,
+  themeColors,
+  containerRef,
+  searchBarOffset,
+  keyEventRef,
+  inputRef,
+  repositionRef,
+  closeRef,
+}: TerminalAutocompleteProps) {
+  const autocomplete = useTerminalAutocomplete({
+    termRef,
+    sessionId,
+    hostId,
+    hostOs,
+    settings,
+    onAcceptText,
+    protocol,
+    getCwd,
+  });
+
+  // Surface the handlers for runtime wiring. They have stable identities
+  // (useCallback over refs), so assigning during render is cheap and mirrors
+  // the wiring Terminal did inline before this was extracted.
+  keyEventRef.current = autocomplete.handleKeyEvent;
+  inputRef.current = autocomplete.handleInput;
+  repositionRef.current = autocomplete.repositionPopup;
+  closeRef.current = autocomplete.closePopup;
+
+  const { state } = autocomplete;
+  if (!visible || !state.popupVisible || state.suggestions.length === 0) {
+    return null;
+  }
+
+  // Portal to body so the popup escapes the terminal container's overflow.
+  return ReactDOM.createPortal(
+    <AutocompletePopup
+      suggestions={state.suggestions}
+      selectedIndex={state.selectedIndex}
+      position={state.popupPosition}
+      cursorLineTop={state.popupCursorLineTop}
+      cursorLineBottom={state.popupCursorLineBottom}
+      visible={state.popupVisible}
+      expandUpward={state.expandUpward}
+      themeColors={themeColors}
+      onSelect={autocomplete.selectSuggestion}
+      subDirPanels={state.subDirPanels}
+      subDirFocusLevel={state.subDirFocusLevel}
+      containerRef={containerRef}
+      onRequestReposition={autocomplete.repositionPopup}
+      searchBarOffset={searchBarOffset}
+      onDismiss={autocomplete.closePopup}
+    />,
+    document.body,
+  );
+}

components/terminal/ZmodemOverwriteDialog.tsx

@@ -0,0 +1,33 @@
+import React, { useState } from "react";
+import { useI18n } from "../../application/i18n/I18nProvider";
+import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter } from "../ui/dialog";
+import { Button } from "../ui/button";
+
+interface Props {
+  filename: string;
+  onRespond: (action: "overwrite" | "skip" | "cancel", applyToRest: boolean) => void;
+}
+
+export const ZmodemOverwriteDialog: React.FC<Props> = ({ filename, onRespond }) => {
+  const { t } = useI18n();
+  const [applyToRest, setApplyToRest] = useState(false);
+  return (
+    <Dialog open onOpenChange={(o) => { if (!o) onRespond("cancel", false); }}>
+      <DialogContent>
+        <DialogHeader>
+          <DialogTitle>{t("zmodem.overwrite.title")}</DialogTitle>
+        </DialogHeader>
+        <p className="text-sm text-muted-foreground break-all">{filename}</p>
+        <label className="flex items-center gap-2 text-sm mt-2">
+          <input type="checkbox" checked={applyToRest} onChange={(e) => setApplyToRest(e.target.checked)} />
+          {t("zmodem.overwrite.applyToRest")}
+        </label>
+        <DialogFooter>
+          <Button variant="ghost" onClick={() => onRespond("cancel", applyToRest)}>{t("zmodem.overwrite.cancel")}</Button>
+          <Button variant="outline" onClick={() => onRespond("skip", applyToRest)}>{t("zmodem.overwrite.skip")}</Button>
+          <Button onClick={() => onRespond("overwrite", applyToRest)}>{t("zmodem.overwrite.overwrite")}</Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+};

components/terminal/autocomplete/AutocompletePopup.tsx

@@ -91,6 +91,32 @@ const DirExpandIndicator: React.FC<{ visible: boolean; color: string }> = ({ vis
   <span style={{ fontSize: "10px", color, opacity: visible ? 0.6 : 0, flexShrink: 0, marginLeft: "2px" }}>›</span>
 );
 
+/** Small key-cap badge shown on the selected row to hint the actionable key. */
+const KeyCap: React.FC<{ label: string; color: string; bg: string }> = ({ label, color, bg }) => (
+  <span
+    style={{
+      display: "inline-flex",
+      alignItems: "center",
+      justifyContent: "center",
+      boxSizing: "border-box",
+      height: "16px",
+      minWidth: "16px",
+      padding: "0 4px",
+      fontSize: "11px",
+      lineHeight: 1,
+      borderRadius: "4px",
+      border: `1px solid color-mix(in srgb, ${color} 35%, transparent)`,
+      color: `color-mix(in srgb, ${color} 80%, ${bg})`,
+      backgroundColor: `color-mix(in srgb, ${color} 12%, ${bg})`,
+      flexShrink: 0,
+      fontFamily:
+        'ui-sans-serif, -apple-system, "Segoe UI", system-ui, sans-serif',
+    }}
+  >
+    {label}
+  </span>
+);
+
 const AutocompletePopup: React.FC<AutocompletePopupProps> = ({
   suggestions,
   selectedIndex,
@@ -361,6 +387,16 @@ const AutocompletePopup: React.FC<AutocompletePopupProps> = ({
               {suggestion.source === "path" && suggestion.fileType === "directory" && (
                 <DirExpandIndicator visible={isSelected || isHovered} color={dimTextColor} />
               )}
+
+              {/* Key hint on the selected row: → expands directories, ↵ runs. */}
+              {isSelected && (
+                <span style={{ display: "flex", gap: "3px", marginLeft: "4px", flexShrink: 0 }}>
+                  {suggestion.source === "path" && suggestion.fileType === "directory" && (
+                    <KeyCap label="→" color={dimTextColor} bg={popupBg} />
+                  )}
+                  <KeyCap label="⏎" color={dimTextColor} bg={popupBg} />
+                </span>
+              )}
             </div>
           );
         })}

components/terminal/autocomplete/livePreviewSequence.ts

@@ -0,0 +1,24 @@
+/**
+ * Compute the keystrokes to send so the terminal input line becomes exactly
+ * `candidate`, given what is currently on the line. Drives the popup
+ * autocomplete live-preview (#1005): moving the selection renders the chosen
+ * suggestion into the command line, and switching / reverting rewrites it.
+ *
+ * - Forward prefix (candidate continues the line): append only the new tail.
+ * - Otherwise: clear the current input, then write the full candidate. POSIX
+ *   shells use Ctrl-U (kill-line); Windows (cmd/PowerShell) uses backspaces
+ *   sized to the current line length.
+ */
+export function computeLivePreviewWrite(input: {
+  currentLine: string;
+  candidate: string;
+  os: string;
+}): string {
+  const { currentLine, candidate, os } = input;
+  if (candidate === currentLine) return "";
+  if (candidate.startsWith(currentLine)) {
+    return candidate.slice(currentLine.length);
+  }
+  const clear = os === "windows" ? "\b".repeat(currentLine.length) : "\x15";
+  return clear + candidate;
+}

components/terminal/autocomplete/useTerminalAutocomplete.ts

@@ -24,6 +24,7 @@ import { preloadCommonSpecs } from "./figSpecLoader";
 import { getXTermCellDimensions } from "./xtermUtils";
 import { listDirectoryEntries, normalizePathTokenForLookup } from "./remotePathCompleter";
 import { decideGhostSuggestion } from "./ghostSuggestionPolicy";
+import { computeLivePreviewWrite } from "./livePreviewSequence";
 
 export interface AutocompleteSettings {
   enabled: boolean;
@@ -46,6 +47,18 @@ export const DEFAULT_AUTOCOMPLETE_SETTINGS: AutocompleteSettings = {
   fastTypingThresholdMs: 40,
 };
 
+/**
+ * Whether completion work is worth doing — i.e. whether anything would
+ * actually be rendered. With both the popup and ghost text disabled, querying
+ * completions only to discard the result is pure main-thread waste, so callers
+ * skip it entirely.
+ */
+export function shouldQueryCompletions(
+  settings: Pick<AutocompleteSettings, "showPopupMenu" | "showGhostText">,
+): boolean {
+  return settings.showPopupMenu || settings.showGhostText;
+}
+
 /** Shared empty state to avoid creating new objects on every reset */
 const EMPTY_STATE: AutocompleteState = Object.freeze({
   suggestions: [],
@@ -253,6 +266,10 @@ export function useTerminalAutocomplete(
   const fetchVersionRef = useRef(0);
   /** Last accepted suggestion text — for accurate history recording on fast Enter after accept */
   const lastAcceptedCommandRef = useRef<string | null>(null);
+  /** The user's typed input that produced the current popup suggestions (live-preview baseline). */
+  const previewBaselineRef = useRef<string>("");
+  /** Whether a popup candidate is currently rendered into the command line (#1005). */
+  const previewActiveRef = useRef(false);
   /** Monotonic counter to invalidate stale async sub-dir fetches */
   const subDirFetchVersionRef = useRef(0);
   /**
@@ -536,6 +553,41 @@ export function useTerminalAutocomplete(
     });
   }, [termRef]);
 
+  /**
+   * Render the full path for a sub-dir entry into the line WITHOUT finalizing
+   * (no clearState). Used for live-preview while navigating sub-dir panels (#1005).
+   */
+  const renderSubDirPath = useCallback((level: number, entry: SubDirEntry) => {
+    const s = stateRef.current;
+    const term = termRef.current;
+    if (!term) return;
+    const panel = s.subDirPanels[level];
+    if (!panel) return;
+    const { prompt } = getAlignedPrompt(
+      term, typedInputBufferRef.current, typedBufferReliableRef.current,
+    );
+    if (!prompt.isAtPrompt) return;
+    const parsed = parseCommandLine(prompt.userInput);
+    const cmdPrefix = parsed.tokens.slice(0, parsed.wordIndex).join(" ")
+      + (parsed.wordIndex > 0 ? " " : "");
+    const currentToken = parsed.currentWord;
+    const quotePrefix = currentToken.startsWith('"') || currentToken.startsWith("'")
+      ? currentToken[0] : "";
+    const quoteSuffix = quotePrefix && currentToken.endsWith(quotePrefix) ? quotePrefix : "";
+    const suffix = entry.type === "directory" ? "/" : "";
+    const entryName = quotePrefix || !/[\\$'"|!<>;#~` ]/.test(entry.name)
+      ? entry.name : shellEscape(entry.name);
+    const newCommand = cmdPrefix + `${quotePrefix}${panel.dirPath}${entryName}${suffix}${quoteSuffix}`;
+    const seq = computeLivePreviewWrite({
+      currentLine: prompt.userInput, candidate: newCommand, os: hostOsRef.current,
+    });
+    if (seq) writeToTerminal(seq);
+    typedInputBufferRef.current = newCommand;
+    typedBufferReliableRef.current = true;
+    previewActiveRef.current = true;
+    lastAcceptedCommandRef.current = newCommand;
+  }, [termRef, writeToTerminal]);
+
   /** Handle selecting a file/directory from any sub-dir panel.
    *  Builds the full path from the panel stack and replaces the current input. */
   const handleSubDirSelect = useCallback((level: number, entry: SubDirEntry) => {
@@ -600,6 +652,15 @@ export function useTerminalAutocomplete(
       return;
     }
 
+    // Nothing will be rendered when both the popup and ghost text are off, so
+    // don't run the (potentially expensive) completion query just to throw the
+    // result away. Clear any stale state and bail before touching history,
+    // fig specs, or remote path lookups.
+    if (!shouldQueryCompletions(settingsRef.current)) {
+      clearState();
+      return;
+    }
+
     // Capture version at start — if it changes during async work, discard results
     const version = ++fetchVersionRef.current;
 
@@ -666,6 +727,9 @@ export function useTerminalAutocomplete(
 
     // Popup
     if (settingsRef.current.showPopupMenu && completions.length > 0) {
+      // Live-preview baseline: the typed input these suggestions completed.
+      previewBaselineRef.current = input;
+      previewActiveRef.current = false;
       const { position, cursorLineTop, cursorLineBottom, expandUpward } = calculatePopupPosition(term, completions.length);
       startTransition(() => {
         setState((prev) => {
@@ -876,6 +940,10 @@ export function useTerminalAutocomplete(
       // User is typing more — invalidate accepted command fallback since the
       // command is being edited further (e.g., accepted "git status" then added " --short")
       lastAcceptedCommandRef.current = null;
+      // The previewed candidate is now edited, so the line is the user's own
+      // text. Drop preview-active so Escape dismisses the popup without
+      // reverting these edits back to the stale baseline (#1005).
+      previewActiveRef.current = false;
 
       // Re-align any visible ghost text to the freshly-updated buffer
       // immediately. Without this the ghost keeps the tail it captured at
@@ -1055,10 +1123,11 @@ export function useTerminalAutocomplete(
       // which is otherwise shadowed by our single-Tab ghost accept.
       if (e.key === "Tab" && !e.ctrlKey && !e.metaKey && !e.altKey && s.subDirFocusLevel < 0) {
         if (s.popupVisible && s.suggestions.length > 0) {
-          e.preventDefault();
-          const selected = s.suggestions[Math.max(0, s.selectedIndex)];
-          if (selected) insertSuggestion(selected, false);
-          return false;
+          // #1005: don't intercept Tab. Keep whatever is currently rendered on
+          // the line and let Tab reach the shell for native completion.
+          clearState();
+          previewActiveRef.current = false;
+          return true;
         }
         // Hide stale ghost text before Tab reaches the shell — the shell's
         // completion will rewrite the line and the old ghost would mislead.
@@ -1087,8 +1156,10 @@ export function useTerminalAutocomplete(
               panels[focusLevel] = { ...p, selectedIndex: newIdx };
               return { ...prev, subDirPanels: panels.slice(0, focusLevel + 1) };
             });
-            // Auto-expand next level if the newly selected item is a directory
+            // Live-render the highlighted entry's full path into the line (#1005).
             const newEntry = focusedPanel.entries[newIdx];
+            if (newEntry) renderSubDirPath(focusLevel, newEntry);
+            // Auto-expand next level if the newly selected item is a directory
             if (newEntry?.type === "directory") {
               expandSubDir(focusLevel, newEntry);
             }
@@ -1144,39 +1215,37 @@ export function useTerminalAutocomplete(
           return true;
         }
 
-        // Main panel navigation
-        if (e.key === "ArrowUp") {
+        // Main panel navigation. The cycle includes a -1 "no selection" slot so
+        // ↑ off the top / ↓ off the bottom reverts to the typed baseline. Moving
+        // the selection live-renders the candidate into the command line (#1005).
+        if (e.key === "ArrowUp" || e.key === "ArrowDown") {
           e.preventDefault();
+          const n = s.suggestions.length;
+          const cur = s.selectedIndex;
+          const next =
+            e.key === "ArrowDown"
+              ? (cur >= n - 1 ? -1 : cur + 1)
+              : (cur <= -1 ? n - 1 : cur - 1);
           setState((prev) => ({
             ...prev,
-            selectedIndex: prev.selectedIndex <= 0 ? prev.suggestions.length - 1 : prev.selectedIndex - 1,
+            selectedIndex: next,
             subDirPanels: [], subDirFocusLevel: -1,
           }));
-          fetchSubDirForIndex(s.selectedIndex <= 0 ? s.suggestions.length - 1 : s.selectedIndex - 1);
-          return false;
-        }
-        if (e.key === "ArrowDown") {
-          e.preventDefault();
-          setState((prev) => ({
-            ...prev,
-            selectedIndex: prev.selectedIndex >= prev.suggestions.length - 1 ? 0 : prev.selectedIndex + 1,
-            subDirPanels: [], subDirFocusLevel: -1,
-          }));
-          fetchSubDirForIndex(s.selectedIndex >= s.suggestions.length - 1 ? 0 : s.selectedIndex + 1);
+          renderPreviewSelection(next);
+          if (next >= 0) fetchSubDirForIndex(next);
           return false;
         }
 
-        // Enter on popup
+        // Enter on popup. The selected candidate is already rendered into the
+        // line by live-preview, so let Enter reach the shell. Don't record here:
+        // handleInput's Enter path records the *actual* line — it uses
+        // lastAcceptedCommandRef (set on select) but falls back to the live
+        // buffer when the user edited the previewed command (typing nulls that
+        // ref), so recording stays accurate in both cases.
         if (e.key === "Enter") {
-          if (s.selectedIndex >= 0) {
-            const selected = s.suggestions[s.selectedIndex];
-            if (selected) {
-              e.preventDefault();
-              insertSuggestion(selected, true);
-              return false;
-            }
-          }
           clearState();
+          previewActiveRef.current = false;
+          return true;
         }
       }
 
@@ -1185,8 +1254,12 @@ export function useTerminalAutocomplete(
       // when only ghost text is showing (ghost text is passive/non-intrusive)
       if (e.key === "Escape" && s.popupVisible) {
         e.preventDefault();
+        if (previewActiveRef.current) {
+          renderPreviewSelection(-1); // restore the typed baseline
+        }
         ghost?.hide();
         clearState();
+        previewActiveRef.current = false;
         return false;
       }
 
@@ -1196,6 +1269,36 @@ export function useTerminalAutocomplete(
     [writeToTerminal],
   );
 
+  /**
+   * Render the suggestion at `index` straight into the command line (Termius
+   * live-preview, #1005). `index < 0` restores the user's typed baseline.
+   */
+  const renderPreviewSelection = useCallback((index: number) => {
+    const s = stateRef.current;
+    const term = termRef.current;
+    if (!term) return;
+    const baseline = previewBaselineRef.current;
+    const candidate =
+      index >= 0 && s.suggestions[index] ? s.suggestions[index].text : baseline;
+    const { prompt } = getAlignedPrompt(
+      term,
+      typedInputBufferRef.current,
+      typedBufferReliableRef.current,
+    );
+    if (!prompt.isAtPrompt) return;
+    const seq = computeLivePreviewWrite({
+      currentLine: prompt.userInput,
+      candidate,
+      os: hostOsRef.current,
+    });
+    if (seq) writeToTerminal(seq);
+    typedInputBufferRef.current = candidate;
+    typedBufferReliableRef.current = true;
+    const isPreview = index >= 0 && candidate !== baseline;
+    previewActiveRef.current = isPreview;
+    lastAcceptedCommandRef.current = isPreview ? candidate : null;
+  }, [termRef, writeToTerminal]);
+
   /**
    * Insert a suggestion into the terminal.
    * @param execute If true, also sends \r to execute the command.

components/terminal/completionGate.test.ts

@@ -0,0 +1,25 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { shouldQueryCompletions } from "./autocomplete/useTerminalAutocomplete.ts";
+
+test("queries completions when the popup menu is enabled", () => {
+  assert.equal(
+    shouldQueryCompletions({ showPopupMenu: true, showGhostText: false }),
+    true,
+  );
+});
+
+test("queries completions when ghost text is enabled", () => {
+  assert.equal(
+    shouldQueryCompletions({ showPopupMenu: false, showGhostText: true }),
+    true,
+  );
+});
+
+test("skips completion work when both popup and ghost text are off", () => {
+  assert.equal(
+    shouldQueryCompletions({ showPopupMenu: false, showGhostText: false }),
+    false,
+  );
+});

components/terminal/connectionLogBuffer.test.ts

@@ -0,0 +1,98 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { createConnectionLogBuffer } from "./connectionLogBuffer.ts";
+
+test("concatenates appended chunks while under the cap", () => {
+  const buf = createConnectionLogBuffer(100);
+  buf.append("foo");
+  buf.append("bar");
+  buf.append("baz");
+  assert.equal(buf.toString(), "foobarbaz");
+});
+
+test("keeps only the last maxChars, matching slice(-max) semantics", () => {
+  const max = 10;
+  const buf = createConnectionLogBuffer(max);
+  const chunks = ["abcd", "efgh", "ijkl", "mnop"]; // 16 chars total
+  let naive = "";
+  for (const c of chunks) {
+    buf.append(c);
+    naive += c;
+  }
+  assert.equal(buf.toString(), naive.slice(-max));
+  assert.equal(buf.toString().length, max);
+});
+
+test("trims a single chunk larger than the cap to its last maxChars", () => {
+  const buf = createConnectionLogBuffer(5);
+  buf.append("0123456789");
+  assert.equal(buf.toString(), "56789");
+});
+
+test("partial-trims the boundary chunk to keep exactly maxChars", () => {
+  const buf = createConnectionLogBuffer(6);
+  buf.append("abcde"); // 5
+  buf.append("fghij"); // total 10 -> keep last 6 => "efghij"
+  assert.equal(buf.toString(), "efghij");
+});
+
+test("stays correct across many small appends (ring semantics)", () => {
+  const max = 50;
+  const buf = createConnectionLogBuffer(max);
+  let naive = "";
+  for (let i = 0; i < 500; i++) {
+    const chunk = `x${i}-`;
+    buf.append(chunk);
+    naive += chunk;
+  }
+  assert.equal(buf.toString(), naive.slice(-max));
+});
+
+test("reset clears the buffer", () => {
+  const buf = createConnectionLogBuffer(100);
+  buf.append("hello");
+  buf.reset();
+  assert.equal(buf.toString(), "");
+  buf.append("world");
+  assert.equal(buf.toString(), "world");
+});
+
+test("ignores empty appends", () => {
+  const buf = createConnectionLogBuffer(100);
+  buf.append("a");
+  buf.append("");
+  buf.append("b");
+  assert.equal(buf.toString(), "ab");
+});
+
+test("keeps the segment count bounded across many tiny appends", () => {
+  // The whole point of the rewrite: trimming must not walk one array entry
+  // per append. With a blockSize of 10 and a 100-char cap, the buffer should
+  // never hold more than ~ceil(cap/blockSize)+1 segments no matter how many
+  // single-char appends arrive once it's at capacity.
+  const maxChars = 100;
+  const blockSize = 10;
+  const buf = createConnectionLogBuffer(maxChars, blockSize);
+  let naive = "";
+  for (let i = 0; i < 10000; i++) {
+    buf.append("x");
+    naive += "x";
+  }
+  assert.ok(
+    buf.segmentCount() <= Math.ceil(maxChars / blockSize) + 1,
+    `segmentCount ${buf.segmentCount()} exceeded the bound`,
+  );
+  assert.equal(buf.toString(), naive.slice(-maxChars));
+});
+
+test("seals and trims whole blocks with a small blockSize", () => {
+  const buf = createConnectionLogBuffer(10, 4);
+  const chunks = ["abcd", "efgh", "ijkl"]; // 12 chars total
+  let naive = "";
+  for (const c of chunks) {
+    buf.append(c);
+    naive += c;
+  }
+  assert.equal(buf.toString(), naive.slice(-10)); // "cdefghijkl"
+});

components/terminal/connectionLogBuffer.ts

@@ -0,0 +1,94 @@
+/**
+ * A bounded, append-only text buffer that retains only the last `maxChars`
+ * characters — the connection log used for diagnostics/replay.
+ *
+ * The naive implementation (`log += chunk; if (log.length > max) log =
+ * log.slice(-max)`) flattens a ~max-length string on *every* append once the
+ * cap is reached — on the render thread, for every output chunk including each
+ * echoed keystroke.
+ *
+ * Instead, data is coalesced into a small, bounded number of fixed-size blocks
+ * (~`maxChars / blockSize`, e.g. ~16 for the 1 MB cap). New data accumulates in
+ * an open `tail`; once it reaches `blockSize` it is sealed into a block. Trimming
+ * the oldest data therefore only ever drops/slices a handful of blocks — never
+ * one array element per append, which would make trim O(number of appends) and
+ * defeat the purpose. Append is amortized O(chunk); the full string is
+ * materialized only on `toString()` (called rarely, on finalize).
+ */
+export interface ConnectionLogBuffer {
+  append(chunk: string): void;
+  toString(): string;
+  reset(): void;
+  /**
+   * Number of internal string segments currently retained. Exposed for tests
+   * to assert the bounded-memory / bounded-trim property.
+   */
+  segmentCount(): number;
+}
+
+const DEFAULT_BLOCK_SIZE = 64 * 1024;
+
+export function createConnectionLogBuffer(
+  maxChars: number,
+  blockSize: number = DEFAULT_BLOCK_SIZE,
+): ConnectionLogBuffer {
+  let blocks: string[] = []; // sealed blocks, oldest first, each up to ~blockSize
+  let tail = ""; // open block currently being filled (newest data)
+  let total = 0; // total retained length across blocks + tail
+
+  const trim = () => {
+    let overflow = total - maxChars;
+    if (overflow <= 0) return;
+    // Drop/slice whole blocks from the front. `blocks.length` is bounded by
+    // ~maxChars/blockSize, so this shift is O(small constant), not O(appends).
+    while (overflow > 0 && blocks.length > 0) {
+      const head = blocks[0];
+      if (head.length <= overflow) {
+        blocks.shift();
+        total -= head.length;
+        overflow -= head.length;
+      } else {
+        blocks[0] = head.slice(overflow);
+        total -= overflow;
+        overflow = 0;
+      }
+    }
+    // Only reachable when the tail alone exceeds the cap (e.g. blockSize >=
+    // maxChars); keep its last `maxChars` characters.
+    if (overflow > 0) {
+      tail = tail.slice(overflow);
+      total -= overflow;
+    }
+  };
+
+  return {
+    append(chunk: string): void {
+      if (!chunk) return;
+      // A single chunk at/over the cap can only contribute its own tail.
+      if (chunk.length >= maxChars) {
+        blocks = [];
+        tail = chunk.slice(chunk.length - maxChars);
+        total = tail.length;
+        return;
+      }
+      tail += chunk;
+      total += chunk.length;
+      if (tail.length >= blockSize) {
+        blocks.push(tail);
+        tail = "";
+      }
+      if (total > maxChars) trim();
+    },
+    toString(): string {
+      return blocks.length > 0 ? blocks.join("") + tail : tail;
+    },
+    reset(): void {
+      blocks = [];
+      tail = "";
+      total = 0;
+    },
+    segmentCount(): number {
+      return blocks.length + (tail.length > 0 ? 1 : 0);
+    },
+  };
+}

components/terminal/hooks/useZmodemTransfer.ts

@@ -27,6 +27,7 @@ const initialState: ZmodemTransferState = {
 
 export function useZmodemTransfer(sessionId: string | null) {
   const [state, setState] = useState<ZmodemTransferState>(initialState);
+  const [overwriteRequest, setOverwriteRequest] = useState<{ requestId: string; filename: string } | null>(null);
   const disposeRef = useRef<(() => void) | null>(null);
 
   const disposeExitRef = useRef<(() => void) | null>(null);
@@ -77,6 +78,10 @@ export function useZmodemTransfer(sessionId: string | null) {
       }
     });
 
+    const disposeOverwrite = bridge.onZmodemOverwriteRequest?.(sessionId, (payload) => {
+      setOverwriteRequest({ requestId: payload.requestId, filename: payload.filename });
+    });
+
     // If the session exits mid-transfer (disconnect, shell exit, etc.),
     // reset state so the progress indicator doesn't stay stuck.
     disposeExitRef.current = bridge.onSessionExit(sessionId, () => {
@@ -86,9 +91,11 @@ export function useZmodemTransfer(sessionId: string | null) {
     return () => {
       disposeRef.current?.();
       disposeRef.current = null;
+      disposeOverwrite?.();
       disposeExitRef.current?.();
       disposeExitRef.current = null;
       setState(initialState);
+      setOverwriteRequest(null);
     };
   }, [sessionId]);
 
@@ -98,5 +105,12 @@ export function useZmodemTransfer(sessionId: string | null) {
     bridge?.cancelZmodem?.(sessionId);
   }, [sessionId]);
 
-  return { ...state, cancel };
+  const respondOverwrite = useCallback((action: "overwrite" | "skip" | "cancel", applyToRest: boolean) => {
+    setOverwriteRequest((req) => {
+      if (req) netcattyBridge.get()?.respondZmodemOverwrite?.({ requestId: req.requestId, action, applyToRest });
+      return null;
+    });
+  }, []);
+
+  return { ...state, cancel, overwriteRequest, respondOverwrite };
 }

components/terminal/livePreviewSequence.test.ts

@@ -0,0 +1,45 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { computeLivePreviewWrite } from "./autocomplete/livePreviewSequence.ts";
+
+test("appends only the tail when the candidate continues the current line", () => {
+  assert.equal(
+    computeLivePreviewWrite({ currentLine: "do", candidate: "docker", os: "linux" }),
+    "cker",
+  );
+});
+
+test("returns empty when the line already equals the candidate", () => {
+  assert.equal(
+    computeLivePreviewWrite({ currentLine: "docker", candidate: "docker", os: "linux" }),
+    "",
+  );
+});
+
+test("clears with Ctrl-U then writes the full candidate on a non-prefix change", () => {
+  assert.equal(
+    computeLivePreviewWrite({ currentLine: "docker", candidate: "df", os: "linux" }),
+    "\x15df",
+  );
+});
+
+test("clears when switching to a shorter prefix candidate", () => {
+  assert.equal(
+    computeLivePreviewWrite({ currentLine: "docker-compose", candidate: "docker", os: "linux" }),
+    "\x15docker",
+  );
+});
+
+test("reverting to the typed baseline clears then rewrites the baseline", () => {
+  assert.equal(
+    computeLivePreviewWrite({ currentLine: "docker", candidate: "do", os: "linux" }),
+    "\x15do",
+  );
+});
+
+test("Windows uses backspaces sized to the current line, not Ctrl-U", () => {
+  assert.equal(
+    computeLivePreviewWrite({ currentLine: "abc", candidate: "xy", os: "windows" }),
+    "\b\b\bxy",
+  );
+});

components/terminal/runtime/altKeyOptions.test.ts

@@ -0,0 +1,23 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { terminalAltKeyOptions } from "./altKeyOptions";
+
+// Issue #1078: with "Use Option as Meta key" enabled, macOS Option must send
+// ESC-prefixed (Meta) sequences. xterm.js gates that on `macOptionIsMeta`. The
+// flag was read from settings but only ever wired to the mouse alt-click
+// behavior, so Option kept emitting layout characters (ƒ, ∫, …) instead of Meta.
+
+test("Option-as-Meta enabled: Option emits Meta and alt-click cursor move is disabled", () => {
+  assert.deepEqual(terminalAltKeyOptions(true), {
+    macOptionIsMeta: true,
+    altClickMovesCursor: false,
+  });
+});
+
+test("Option-as-Meta disabled: xterm keeps default macOS Option behavior", () => {
+  assert.deepEqual(terminalAltKeyOptions(false), {
+    macOptionIsMeta: false,
+    altClickMovesCursor: true,
+  });
+});

components/terminal/runtime/altKeyOptions.ts

@@ -0,0 +1,20 @@
+export interface TerminalAltKeyOptions {
+  /** xterm.js: treat macOS Option as the Meta key (emit ESC-prefixed sequences). */
+  macOptionIsMeta: boolean;
+  /** xterm.js: Option+click moves the cursor. Must be off when Option is Meta. */
+  altClickMovesCursor: boolean;
+}
+
+/**
+ * Map the user's "Use Option as Meta key" setting to xterm.js options.
+ *
+ * Kept in one place so terminal init (createXTermRuntime) and the live settings
+ * sync (Terminal.tsx) can't drift — that drift is what left `macOptionIsMeta`
+ * unset everywhere and broke Option/Meta shortcuts on macOS (issue #1078).
+ */
+export function terminalAltKeyOptions(altAsMeta: boolean): TerminalAltKeyOptions {
+  return {
+    macOptionIsMeta: altAsMeta,
+    altClickMovesCursor: !altAsMeta,
+  };
+}

components/terminal/runtime/createTerminalSessionStarters.ts

@@ -27,6 +27,7 @@ import {
   syncPromptLineBreakState,
   type PromptLineBreakState,
 } from "./promptLineBreak";
+import { createOutputFlowController, type OutputFlowController } from "./outputFlowController";
 
 /**
  * Per-connection token for stale-timer detection. The renderer reuses the
@@ -97,6 +98,8 @@ type TerminalBackendApi = {
   ) => (() => void) | undefined;
   writeToSession: (sessionId: string, data: string, options?: { automated?: boolean }) => void;
   resizeSession: (sessionId: string, cols: number, rows: number) => void;
+  /** Pause/resume the source stream for output back-pressure (optional). */
+  setSessionFlowPaused?: (sessionId: string, paused: boolean) => void;
 };
 
 export type PendingAuth = {
@@ -251,6 +254,38 @@ const enqueueTerminalWrite = (
   }
 };
 
+// Output back-pressure. Without this the renderer can't slow a flooding source,
+// so a busy stream grows the write queue and xterm's buffer unbounded. The
+// controller tracks bytes received-but-not-yet-rendered and asks the main
+// process to pause/resume the session's source stream at these watermarks.
+const FLOW_HIGH_WATER_MARK = 256 * 1024; // pause the source above ~256KB backlog
+const FLOW_LOW_WATER_MARK = 64 * 1024; // resume once drained to ~64KB
+
+const terminalFlowControllers = new WeakMap<XTerm, OutputFlowController>();
+
+const getFlowController = (
+  ctx: TerminalSessionStartersContext,
+  term: XTerm,
+): OutputFlowController => {
+  let controller = terminalFlowControllers.get(term);
+  if (!controller) {
+    controller = createOutputFlowController({
+      highWaterMark: FLOW_HIGH_WATER_MARK,
+      lowWaterMark: FLOW_LOW_WATER_MARK,
+      onPause: () => {
+        const id = ctx.sessionRef.current;
+        if (id) ctx.terminalBackend.setSessionFlowPaused?.(id, true);
+      },
+      onResume: () => {
+        const id = ctx.sessionRef.current;
+        if (id) ctx.terminalBackend.setSessionFlowPaused?.(id, false);
+      },
+    });
+    terminalFlowControllers.set(term, controller);
+  }
+  return controller;
+};
+
 const writeTerminalLine = (
   ctx: TerminalSessionStartersContext,
   term: XTerm,
@@ -268,6 +303,8 @@ const writeSessionData = (
   term: XTerm,
   data: string,
 ) => {
+  const flow = getFlowController(ctx, term);
+  flow.received(data.length);
   enqueueTerminalWrite(term, (done) => {
     const settings = ctx.terminalSettingsRef?.current ?? ctx.terminalSettings;
     const forcePromptNewLine = settings?.forcePromptNewLine ?? false;
@@ -301,6 +338,8 @@ const writeSessionData = (
         handleTerminalOutputAutoScroll(ctx, term);
       }
       done();
+      // Acknowledge the chunk so back-pressure can ease once xterm catches up.
+      flow.written(data.length);
     };
 
     term.write(displayData, afterWrite);
@@ -320,6 +359,8 @@ const attachSessionToTerminal = (
   },
 ) => {
   ctx.sessionRef.current = id;
+  // Clear any stale back-pressure accounting from a prior session on this term.
+  getFlowController(ctx, term).reset();
   ctx.onSessionAttached?.(id);
 
   ctx.disposeDataRef.current = ctx.terminalBackend.onSessionData(id, (chunk) => {
@@ -1204,6 +1245,7 @@ export const createTerminalSessionStarters = (ctx: TerminalSessionStartersContex
       });
 
       ctx.sessionRef.current = id;
+      getFlowController(ctx, term).reset();
       ctx.disposeDataRef.current = ctx.terminalBackend.onSessionData(id, (chunk) => {
         writeSessionData(ctx, term, chunk);
         if (!ctx.hasConnectedRef.current) {

components/terminal/runtime/createXTermRuntime.ts

@@ -43,6 +43,9 @@ import {
 } from "./kittyKeyboardProtocol";
 import { installKittyKeyboardProtocolHandlers } from "./kittyKeyboardRuntime";
 import { installUserCursorPreferenceGuard } from "./cursorPreference";
+import { terminalAltKeyOptions } from "./altKeyOptions";
+import { optionArrowWordJumpSequence } from "./optionArrowWordJump";
+import { watchDevicePixelRatio } from "./rendererDprWatch";
 import { handleSerialLineModeInput } from "./serialLineInput";
 import {
   markExpectedTerminalCursorPositionReport,
@@ -79,6 +82,13 @@ export type XTermRuntime = {
   /** Current working directory detected via OSC 7 */
   currentCwd: string | undefined;
   keywordHighlighter: KeywordHighlighter;
+  /**
+   * Clear the WebGL renderer's glyph texture atlas so glyphs re-rasterize on the
+   * next frame. No-op when the DOM renderer is active. Used to recover from the
+   * persistent "garbled / 花屏" corruption (issue #1049) that the WebGL atlas can
+   * fall into after font changes or device pixel ratio changes.
+   */
+  clearTextureAtlas: () => void;
 };
 
 export type CreateXTermRuntimeContext = {
@@ -286,7 +296,7 @@ export const createXTermRuntime = (ctx: CreateXTermRuntimeContext): XTermRuntime
     smoothScrollDuration,
     scrollOnUserInput,
     macOptionClickForcesSelection: true,
-    altClickMovesCursor: !altIsMeta,
+    ...terminalAltKeyOptions(altIsMeta),
     wordSeparator,
     theme: {
       ...ctx.terminalTheme.colors,
@@ -386,6 +396,45 @@ export const createXTermRuntime = (ctx: CreateXTermRuntimeContext): XTermRuntime
     ? "dom"
     : "webgl";
 
+  // The WebGL renderer caches rasterized glyphs in a texture atlas. Heavy TUIs
+  // (claude code / gemini cli / opencode and other full-screen agents), font
+  // changes, and device pixel ratio changes can leave that atlas in a corrupted
+  // state that persists for the life of the terminal — the "garbled / 花屏"
+  // report in issue #1049 where only opening a brand-new terminal helps. Clearing
+  // the atlas forces glyphs to re-rasterize at the correct scale on the next
+  // frame. No-op for the DOM renderer.
+  const clearWebglTextureAtlas = () => {
+    if (!webglAddon) return;
+    try {
+      webglAddon.clearTextureAtlas();
+    } catch (err) {
+      logger.warn("[XTerm] clearTextureAtlas failed", err);
+    }
+  };
+
+  // Recover the renderer when the device pixel ratio changes (moving the window
+  // between monitors with different DPI, or changing OS display scaling — a
+  // common Windows trigger). matchMedia change does not fire a normal resize, so
+  // this is needed in addition to the resize handling below.
+  let stopDprWatch: () => void = () => {};
+  if (
+    typeof window !== "undefined" &&
+    typeof window.matchMedia === "function"
+  ) {
+    stopDprWatch = watchDevicePixelRatio({
+      getDevicePixelRatio: () => window.devicePixelRatio || 1,
+      matchMedia: (query) => window.matchMedia(query),
+      onChange: () => {
+        clearWebglTextureAtlas();
+        try {
+          fitAddon.fit();
+        } catch (err) {
+          logger.warn("[XTerm] fit after devicePixelRatio change failed", err);
+        }
+      },
+    });
+  }
+
   const webLinksAddon = new WebLinksAddon((event, uri) => {
     const currentLinkModifier = ctx.terminalSettingsRef.current?.linkModifier ?? "none";
     let shouldOpen = false;
@@ -609,6 +658,29 @@ export const createXTermRuntime = (ctx: CreateXTermRuntimeContext): XTermRuntime
       }
     }
 
+    // macOS Option+←/→ → Meta-b / Meta-f so the shell jumps by word (discussion
+    // #826). After kitty mode so apps using the kitty protocol keep their own
+    // arrow encoding; read live so the toggle applies without reconnecting.
+    const wordJumpSequence = optionArrowWordJumpSequence(
+      e,
+      ctx.terminalSettingsRef.current?.optionArrowWordJump ?? false,
+      isMacPlatform(),
+    );
+    if (wordJumpSequence) {
+      const id = ctx.sessionRef.current;
+      if (id) {
+        e.preventDefault();
+        e.stopPropagation();
+        ctx.onAutocompleteInput?.(wordJumpSequence);
+        ctx.terminalBackend.writeToSession(id, wordJumpSequence);
+        if (ctx.isBroadcastEnabledRef.current && ctx.onBroadcastInputRef.current) {
+          ctx.onBroadcastInputRef.current(wordJumpSequence, ctx.sessionId);
+        }
+        scrollToBottomAfterInput(wordJumpSequence);
+        return false;
+      }
+    }
+
     return true;
   });
 
@@ -858,6 +930,9 @@ export const createXTermRuntime = (ctx: CreateXTermRuntimeContext): XTermRuntime
   let resizeTimeout: NodeJS.Timeout | null = null;
   const resizeDebounceMs = XTERM_PERFORMANCE_CONFIG.resize.debounceMs;
   term.onResize(({ cols, rows }) => {
+    // A reflow can leave stale glyphs in the WebGL atlas; clear it so the new
+    // dimensions re-rasterize cleanly (issue #1049).
+    clearWebglTextureAtlas();
     const id = ctx.sessionRef.current;
     if (!id) return;
     if (resizeTimeout) clearTimeout(resizeTimeout);
@@ -876,8 +951,10 @@ export const createXTermRuntime = (ctx: CreateXTermRuntimeContext): XTermRuntime
     serializeAddon,
     searchAddon,
     keywordHighlighter,
+    clearTextureAtlas: clearWebglTextureAtlas,
     dispose: () => {
       cleanupMiddleClick?.();
+      stopDprWatch();
       keywordHighlighter.dispose();
       eraseScrollbackDisposable.dispose();
       for (const disposable of cursorPositionReportRequestDisposables) {

components/terminal/runtime/optionArrowWordJump.test.ts

@@ -0,0 +1,51 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { optionArrowWordJumpSequence } from "./optionArrowWordJump";
+
+// Discussion #826: on macOS, Option+←/→ defaults to xterm's ^[[1;3D / ^[[1;3C,
+// which most shells don't bind. When enabled, remap them to Meta-b / Meta-f so
+// readline/zle does backward-word / forward-word out of the box (Termius-style).
+// Gated to macOS so the syncable setting can't rewrite Alt+←/→ on other platforms.
+
+const ev = (over: Partial<Parameters<typeof optionArrowWordJumpSequence>[0]> = {}) => ({
+  key: "ArrowLeft",
+  altKey: true,
+  ctrlKey: false,
+  metaKey: false,
+  shiftKey: false,
+  ...over,
+});
+
+test("Option+Left → Meta-b (backward-word) when enabled on macOS", () => {
+  assert.equal(optionArrowWordJumpSequence(ev({ key: "ArrowLeft" }), true, true), "\x1bb");
+});
+
+test("Option+Right → Meta-f (forward-word) when enabled on macOS", () => {
+  assert.equal(optionArrowWordJumpSequence(ev({ key: "ArrowRight" }), true, true), "\x1bf");
+});
+
+test("not macOS → null (don't rewrite Alt+←/→ on Linux/Windows even if synced on)", () => {
+  assert.equal(optionArrowWordJumpSequence(ev({ key: "ArrowLeft" }), true, false), null);
+  assert.equal(optionArrowWordJumpSequence(ev({ key: "ArrowRight" }), true, false), null);
+});
+
+test("disabled → null (xterm default ^[[1;3D/C is kept)", () => {
+  assert.equal(optionArrowWordJumpSequence(ev({ key: "ArrowLeft" }), false, true), null);
+  assert.equal(optionArrowWordJumpSequence(ev({ key: "ArrowRight" }), false, true), null);
+});
+
+test("no Option held → null", () => {
+  assert.equal(optionArrowWordJumpSequence(ev({ altKey: false }), true, true), null);
+});
+
+test("extra modifiers with Option → null (don't hijack Shift/Ctrl/Cmd combos)", () => {
+  assert.equal(optionArrowWordJumpSequence(ev({ shiftKey: true }), true, true), null);
+  assert.equal(optionArrowWordJumpSequence(ev({ ctrlKey: true }), true, true), null);
+  assert.equal(optionArrowWordJumpSequence(ev({ metaKey: true }), true, true), null);
+});
+
+test("non-arrow keys → null", () => {
+  assert.equal(optionArrowWordJumpSequence(ev({ key: "ArrowUp" }), true, true), null);
+  assert.equal(optionArrowWordJumpSequence(ev({ key: "f" }), true, true), null);
+});

components/terminal/runtime/optionArrowWordJump.ts

@@ -0,0 +1,33 @@
+export interface OptionArrowKeyEvent {
+  key: string;
+  altKey: boolean;
+  ctrlKey: boolean;
+  metaKey: boolean;
+  shiftKey: boolean;
+}
+
+/**
+ * macOS Option+←/→ word-jump (discussion #826).
+ *
+ * When enabled, maps a bare Option+Left/Right to the Meta-b / Meta-f sequence so
+ * readline/zle does backward-word / forward-word without per-host bindkey setup.
+ * Returns the bytes to send, or null when the mapping doesn't apply (disabled,
+ * non-macOS, not an arrow, or other modifiers held) — in which case xterm's
+ * default ^[[1;3D / ^[[1;3C is left untouched.
+ *
+ * Gated to macOS (`isMac`): the setting is syncable, so without the gate,
+ * enabling it on a Mac would also rewrite Alt+←/→ on synced Linux/Windows
+ * devices (discussion #826 review).
+ */
+export function optionArrowWordJumpSequence(
+  e: OptionArrowKeyEvent,
+  enabled: boolean,
+  isMac: boolean,
+): string | null {
+  if (!enabled || !isMac) return null;
+  // Only a bare Option+Arrow — leave Shift/Ctrl/Cmd combos to xterm's defaults.
+  if (!e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) return null;
+  if (e.key === "ArrowLeft") return "\x1bb"; // Meta-b → backward-word
+  if (e.key === "ArrowRight") return "\x1bf"; // Meta-f → forward-word
+  return null;
+}

components/terminal/runtime/outputFlowController.test.ts

@@ -0,0 +1,89 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { createOutputFlowController } from "./outputFlowController.ts";
+
+function make(high = 100, low = 30) {
+  const events: string[] = [];
+  const controller = createOutputFlowController({
+    highWaterMark: high,
+    lowWaterMark: low,
+    onPause: () => events.push("pause"),
+    onResume: () => events.push("resume"),
+  });
+  return { controller, events };
+}
+
+test("does not pause while below the high watermark", () => {
+  const { controller, events } = make(100, 30);
+  controller.received(50);
+  controller.received(49); // 99 < 100
+  assert.deepEqual(events, []);
+  assert.equal(controller.isPaused(), false);
+});
+
+test("pauses once when crossing the high watermark", () => {
+  const { controller, events } = make(100, 30);
+  controller.received(60);
+  controller.received(60); // 120 >= 100 -> pause
+  assert.deepEqual(events, ["pause"]);
+  assert.equal(controller.isPaused(), true);
+  // Further received while already paused must not re-fire pause.
+  controller.received(100);
+  assert.deepEqual(events, ["pause"]);
+});
+
+test("resumes once when draining to at/below the low watermark", () => {
+  const { controller, events } = make(100, 30);
+  controller.received(120); // pause
+  controller.written(50); // 70 still > 30, no resume
+  assert.deepEqual(events, ["pause"]);
+  controller.written(50); // 20 <= 30 -> resume
+  assert.deepEqual(events, ["pause", "resume"]);
+  assert.equal(controller.isPaused(), false);
+});
+
+test("does not resume when still above the low watermark", () => {
+  const { controller, events } = make(100, 30);
+  controller.received(120); // pause
+  controller.written(80); // 40 > 30
+  assert.deepEqual(events, ["pause"]);
+  assert.equal(controller.isPaused(), true);
+});
+
+test("never lets pending go negative", () => {
+  const { controller } = make(100, 30);
+  controller.received(10);
+  controller.written(50); // over-written
+  assert.equal(controller.pendingBytes(), 0);
+});
+
+test("supports repeated pause/resume cycles", () => {
+  const { controller, events } = make(100, 30);
+  controller.received(120); // pause
+  controller.written(120); // resume (0 <= 30)
+  controller.received(120); // pause again
+  controller.written(120); // resume again
+  assert.deepEqual(events, ["pause", "resume", "pause", "resume"]);
+});
+
+test("reset clears state without firing callbacks", () => {
+  const { controller, events } = make(100, 30);
+  controller.received(120); // pause
+  controller.reset();
+  assert.equal(controller.isPaused(), false);
+  assert.equal(controller.pendingBytes(), 0);
+  assert.deepEqual(events, ["pause"]); // reset itself is silent
+  // A fresh cycle works after reset.
+  controller.received(120);
+  assert.deepEqual(events, ["pause", "pause"]);
+});
+
+test("ignores non-positive amounts", () => {
+  const { controller, events } = make(100, 30);
+  controller.received(0);
+  controller.written(0);
+  controller.received(-5);
+  assert.equal(controller.pendingBytes(), 0);
+  assert.deepEqual(events, []);
+});

components/terminal/runtime/outputFlowController.ts

@@ -0,0 +1,73 @@
+/**
+ * Watermark-based flow control for terminal output.
+ *
+ * SSH/PTY output has no back-pressure by default: the source streams as fast as
+ * it can, the main process forwards it over IPC, and the renderer queues every
+ * chunk into xterm. When output outpaces rendering (e.g. `cat` of a big file, a
+ * noisy build, `tail -f`, `yes`), the renderer-side backlog and xterm's internal
+ * buffer grow without bound — memory climbs and the whole UI, typing included,
+ * janks.
+ *
+ * This tracks bytes that have been received but not yet acknowledged by xterm's
+ * write callback. When the backlog crosses `highWaterMark` it asks the caller to
+ * pause the source; once it drains back to `lowWaterMark` it asks to resume. The
+ * hysteresis gap avoids rapid pause/resume flapping. During interactive use the
+ * backlog hovers near zero, so this never engages.
+ */
+export interface OutputFlowController {
+  /** Account bytes handed to xterm (call when a chunk is received). */
+  received(bytes: number): void;
+  /** Account bytes whose xterm write callback has fired. */
+  written(bytes: number): void;
+  /** Clear all state (e.g. on a fresh session attach). Fires no callbacks. */
+  reset(): void;
+  pendingBytes(): number;
+  isPaused(): boolean;
+}
+
+export interface OutputFlowControllerOptions {
+  highWaterMark: number;
+  lowWaterMark: number;
+  /** Asked to pause the source when the backlog crosses the high watermark. */
+  onPause: () => void;
+  /** Asked to resume the source when the backlog drains to the low watermark. */
+  onResume: () => void;
+}
+
+export function createOutputFlowController(
+  options: OutputFlowControllerOptions,
+): OutputFlowController {
+  const { highWaterMark, lowWaterMark, onPause, onResume } = options;
+  let pending = 0;
+  let paused = false;
+
+  return {
+    received(bytes: number): void {
+      if (bytes <= 0) return;
+      pending += bytes;
+      if (!paused && pending >= highWaterMark) {
+        paused = true;
+        onPause();
+      }
+    },
+    written(bytes: number): void {
+      if (bytes <= 0) return;
+      pending -= bytes;
+      if (pending < 0) pending = 0;
+      if (paused && pending <= lowWaterMark) {
+        paused = false;
+        onResume();
+      }
+    },
+    reset(): void {
+      pending = 0;
+      paused = false;
+    },
+    pendingBytes(): number {
+      return pending;
+    },
+    isPaused(): boolean {
+      return paused;
+    },
+  };
+}

components/terminal/runtime/rendererDprWatch.test.ts

@@ -0,0 +1,158 @@
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import {
+  type MediaQueryListLike,
+  watchDevicePixelRatio,
+} from "./rendererDprWatch";
+
+class FakeMediaQueryList implements MediaQueryListLike {
+  readonly query: string;
+  modernListeners: Array<() => void> = [];
+  legacyListeners: Array<() => void> = [];
+  private readonly supportsModern: boolean;
+
+  constructor(query: string, supportsModern = true) {
+    this.query = query;
+    this.supportsModern = supportsModern;
+    if (!supportsModern) {
+      // Strip the modern API to emulate legacy environments.
+      this.addEventListener = undefined;
+      this.removeEventListener = undefined;
+    }
+  }
+
+  addEventListener? = (_type: "change", listener: () => void) => {
+    this.modernListeners.push(listener);
+  };
+
+  removeEventListener? = (_type: "change", listener: () => void) => {
+    this.modernListeners = this.modernListeners.filter((l) => l !== listener);
+  };
+
+  addListener = (listener: () => void) => {
+    this.legacyListeners.push(listener);
+  };
+
+  removeListener = (listener: () => void) => {
+    this.legacyListeners = this.legacyListeners.filter((l) => l !== listener);
+  };
+
+  trigger() {
+    for (const l of [...this.modernListeners, ...this.legacyListeners]) l();
+  }
+
+  get listenerCount() {
+    return this.modernListeners.length + this.legacyListeners.length;
+  }
+}
+
+function makeEnv(initialDpr: number, supportsModern = true) {
+  let dpr = initialDpr;
+  const created: FakeMediaQueryList[] = [];
+  return {
+    created,
+    getDevicePixelRatio: () => dpr,
+    matchMedia: (query: string) => {
+      const mql = new FakeMediaQueryList(query, supportsModern);
+      created.push(mql);
+      return mql;
+    },
+    setDpr: (value: number) => {
+      dpr = value;
+    },
+  };
+}
+
+test("registers a change listener for the current devicePixelRatio", () => {
+  const env = makeEnv(1);
+  watchDevicePixelRatio({
+    getDevicePixelRatio: env.getDevicePixelRatio,
+    matchMedia: env.matchMedia,
+    onChange: () => {},
+  });
+
+  assert.equal(env.created.length, 1);
+  assert.equal(env.created[0].query, "(resolution: 1dppx)");
+  assert.equal(env.created[0].listenerCount, 1);
+});
+
+test("invokes onChange when the media query reports a change", () => {
+  const env = makeEnv(1);
+  let calls = 0;
+  watchDevicePixelRatio({
+    getDevicePixelRatio: env.getDevicePixelRatio,
+    matchMedia: env.matchMedia,
+    onChange: () => {
+      calls += 1;
+    },
+  });
+
+  env.setDpr(2);
+  env.created[0].trigger();
+
+  assert.equal(calls, 1);
+});
+
+test("re-registers for the new ratio so subsequent changes still fire", () => {
+  const env = makeEnv(1);
+  let calls = 0;
+  watchDevicePixelRatio({
+    getDevicePixelRatio: env.getDevicePixelRatio,
+    matchMedia: env.matchMedia,
+    onChange: () => {
+      calls += 1;
+    },
+  });
+
+  env.setDpr(2);
+  env.created[0].trigger();
+
+  assert.equal(env.created.length, 2);
+  assert.equal(env.created[1].query, "(resolution: 2dppx)");
+  // The stale listener must be detached so it cannot double-fire.
+  assert.equal(env.created[0].listenerCount, 0);
+
+  env.setDpr(3);
+  env.created[1].trigger();
+
+  assert.equal(calls, 2);
+});
+
+test("cleanup stops further onChange callbacks", () => {
+  const env = makeEnv(1);
+  let calls = 0;
+  const stop = watchDevicePixelRatio({
+    getDevicePixelRatio: env.getDevicePixelRatio,
+    matchMedia: env.matchMedia,
+    onChange: () => {
+      calls += 1;
+    },
+  });
+
+  stop();
+
+  assert.equal(env.created[0].listenerCount, 0);
+  env.created[0].trigger();
+  assert.equal(calls, 0);
+});
+
+test("falls back to addListener/removeListener when addEventListener is unavailable", () => {
+  const env = makeEnv(1, /* supportsModern */ false);
+  let calls = 0;
+  const stop = watchDevicePixelRatio({
+    getDevicePixelRatio: env.getDevicePixelRatio,
+    matchMedia: env.matchMedia,
+    onChange: () => {
+      calls += 1;
+    },
+  });
+
+  assert.equal(env.created[0].legacyListeners.length, 1);
+  env.created[0].trigger();
+  assert.equal(calls, 1);
+
+  stop();
+  // After cleanup the most recently registered query has no listeners.
+  const latest = env.created[env.created.length - 1];
+  assert.equal(latest.listenerCount, 0);
+});

components/terminal/runtime/rendererDprWatch.ts

@@ -0,0 +1,72 @@
+/**
+ * Watches for devicePixelRatio changes (e.g. moving the window between monitors
+ * with different DPI, or changing the OS display scaling on Windows) and invokes
+ * a callback so the renderer can be repaired.
+ *
+ * The WebGL renderer caches rasterized glyphs in a texture atlas keyed to the
+ * device pixel ratio at creation time. When the ratio changes the cached glyphs
+ * are drawn at the wrong scale, producing the persistent "garbled / 花屏"
+ * corruption reported in issue #1049 that only goes away when a brand-new
+ * terminal is opened. xterm.js recommends calling `clearTextureAtlas()` on DPR
+ * change so glyphs re-rasterize at the new scale.
+ *
+ * `matchMedia('(resolution: Ndppx)')` only matches a single ratio, so after each
+ * change we must re-register the listener against the new ratio.
+ */
+export interface MediaQueryListLike {
+  addEventListener?: (type: "change", listener: () => void) => void;
+  removeEventListener?: (type: "change", listener: () => void) => void;
+  // Legacy API (older Safari / Electron) where addEventListener is unavailable.
+  addListener?: (listener: () => void) => void;
+  removeListener?: (listener: () => void) => void;
+}
+
+export interface WatchDevicePixelRatioOptions {
+  getDevicePixelRatio: () => number;
+  matchMedia: (query: string) => MediaQueryListLike;
+  onChange: () => void;
+}
+
+/**
+ * Start watching for devicePixelRatio changes. Returns a cleanup function that
+ * removes the active listener.
+ */
+export function watchDevicePixelRatio(
+  options: WatchDevicePixelRatioOptions,
+): () => void {
+  const { getDevicePixelRatio, matchMedia, onChange } = options;
+  let current: { mql: MediaQueryListLike; listener: () => void } | null = null;
+
+  const detach = () => {
+    if (!current) return;
+    const { mql, listener } = current;
+    if (mql.removeEventListener) {
+      mql.removeEventListener("change", listener);
+    } else if (mql.removeListener) {
+      mql.removeListener(listener);
+    }
+    current = null;
+  };
+
+  const attach = () => {
+    const dpr = getDevicePixelRatio();
+    const mql = matchMedia(`(resolution: ${dpr}dppx)`);
+    const listener = () => {
+      // A media query only matches the ratio it was created with, so detach the
+      // stale listener and re-register against the new ratio before notifying.
+      detach();
+      attach();
+      onChange();
+    };
+    if (mql.addEventListener) {
+      mql.addEventListener("change", listener);
+    } else if (mql.addListener) {
+      mql.addListener(listener);
+    }
+    current = { mql, listener };
+  };
+
+  attach();
+
+  return detach;
+}

domain/host.test.ts

@@ -3,12 +3,14 @@ import assert from "node:assert/strict";
 
 import type { Host } from "./models.ts";
 import {
+  detectVendorFromSshVersion,
   normalizePrimaryTelnetState,
   resolveHostKeepalive,
   resolveTelnetPort,
   resolveTelnetPassword,
   resolveTelnetUsername,
   sanitizeHost,
+  shouldProbeSessionCwd,
   upsertHostById,
 } from "./host.ts";
 
@@ -158,6 +160,39 @@ test("sanitizeHost keeps a still-valid fontFamily untouched", () => {
   assert.equal(after.fontFamilyOverride, true);
 });
 
+test("detectVendorFromSshVersion recognizes legacy Huawei VRP dash banner", () => {
+  assert.equal(detectVendorFromSshVersion("-"), "huawei");
+  assert.equal(detectVendorFromSshVersion("SSH-2.0--"), "huawei");
+});
+
+test("shouldProbeSessionCwd allows the probe on a plain Linux host", () => {
+  assert.equal(
+    shouldProbeSessionCwd({ isNetworkDevice: false, remoteSshVersion: "OpenSSH_9.6" }),
+    true,
+  );
+});
+
+test("shouldProbeSessionCwd skips the probe on an already-classified network device", () => {
+  // Reconnect / manual deviceType='network': host.distro already says network.
+  assert.equal(
+    shouldProbeSessionCwd({ isNetworkDevice: true, remoteSshVersion: "OpenSSH_9.6" }),
+    false,
+  );
+});
+
+test("shouldProbeSessionCwd skips the probe when the SSH banner reveals a network vendor", () => {
+  // First connect to a brand-new Huawei VRP: host.distro not persisted yet, so
+  // isNetworkDevice is still false — the banner is the only signal (#1043).
+  assert.equal(
+    shouldProbeSessionCwd({ isNetworkDevice: false, remoteSshVersion: "-" }),
+    false,
+  );
+  assert.equal(
+    shouldProbeSessionCwd({ isNetworkDevice: false, remoteSshVersion: "SSH-1.99--" }),
+    false,
+  );
+});
+
 const GLOBAL_KEEPALIVE = { keepaliveInterval: 30, keepaliveCountMax: 10 };
 
 test("resolveHostKeepalive falls back to global when override is not set", () => {

domain/host.ts

@@ -78,7 +78,7 @@ export const normalizeDistroId = (value?: string) => {
  * plain `OpenSSH_*` with no distinct vendor marker.
  */
 export const detectVendorFromSshVersion = (softwareVersion?: string): '' | NetworkDeviceVendor => {
-  const s = (softwareVersion || '').trim();
+  const s = (softwareVersion || '').trim().replace(/^SSH-(?:2\.0|1\.99)-/i, '');
   if (!s) return '';
 
   // Cisco family — IOS, IOS XA, Wireless LAN Controller
@@ -97,6 +97,7 @@ export const detectVendorFromSshVersion = (softwareVersion?: string): '' | Netwo
   if (/^NetScreen\b/.test(s)) return 'juniper';
 
   // Huawei VRP and related products
+  if (s === '-') return 'huawei';
   if (/^HUAWEI[-_]/i.test(s)) return 'huawei';
   if (/^VRP-/i.test(s)) return 'huawei';
 
@@ -135,6 +136,24 @@ export const classifyDistroId = (distroId?: string): DeviceClass => {
   return 'other';
 };
 
+/**
+ * Decide whether it is safe to run the post-connect `pwd` probe that
+ * discovers the session's working directory. The probe opens an extra exec
+ * channel running a POSIX-shell script; strict network-device CLIs such as
+ * Huawei VRP respond by closing the whole SSH session (#1043), so it must be
+ * skipped for them.
+ *
+ * `isNetworkDevice` covers hosts we already classified (a reconnect, or an
+ * explicit `deviceType: 'network'`). On a brand-new host that field is not
+ * populated yet, so we also inspect the SSH server identification banner —
+ * captured for free at handshake — which identifies most vendors directly.
+ */
+export const shouldProbeSessionCwd = (opts: {
+  isNetworkDevice: boolean;
+  remoteSshVersion?: string;
+}): boolean =>
+  !opts.isNetworkDevice && !detectVendorFromSshVersion(opts.remoteSshVersion);
+
 export const getEffectiveHostDistro = (
   host?: Pick<Host, 'distro' | 'manualDistro' | 'distroMode'> | null,
 ) => {

domain/models.ts

@@ -493,6 +493,7 @@ export interface TerminalSettings {
 
   // Keyboard
   altAsMeta: boolean; // Use ⌥ as the Meta key
+  optionArrowWordJump: boolean; // macOS: Option+←/→ send Meta-b/f for word jump
   scrollOnInput: boolean; // Scroll terminal to bottom on input
   scrollOnOutput: boolean; // Scroll terminal to bottom on output
   scrollOnKeyPress: boolean; // Scroll terminal to bottom on key press
@@ -692,6 +693,7 @@ const DEFAULT_TERMINAL_SETTINGS: TerminalSettings = {
   cursorBlink: true,
   minimumContrastRatio: 1,
   altAsMeta: false,
+  optionArrowWordJump: false,
   scrollOnInput: true,
   scrollOnOutput: false,
   scrollOnKeyPress: false,

electron/bridges/ai/shellUtils.cjs

@@ -58,6 +58,32 @@ function extractTrailingIdlePrompt(output) {
   return "";
 }
 
+// bash and csh/tcsh print a banner to the terminal right before exiting due to
+// the shell's TMOUT idle-timeout setting ("timed out waiting for input:
+// auto-logout" / "auto-logout"). That exit is a clean shell exit — numeric
+// code, no signal — so it is indistinguishable from a user-typed `exit` by
+// exit code alone (verified: bash auto-logout exits 0). The banner is the only
+// reliable discriminator, letting the SSH bridge keep the tab open for
+// reconnect instead of auto-closing it (#1062, regression of #977).
+const IDLE_AUTO_LOGOUT_PATTERN = /(?:timed out waiting for input:\s*)?auto-?logout$/i;
+
+function looksLikeIdleAutoLogout(outputTail) {
+  if (typeof outputTail !== "string" || !outputTail) return false;
+  // The shell prints this banner on its own line as the very last thing before
+  // it exits, so anchor on the final non-empty line rather than a loose
+  // substring. Otherwise unrelated output that merely mentions "auto-logout"
+  // (e.g. `grep auto-logout /etc/profile`) followed by an intentional `exit`
+  // would be misclassified as a timeout and wrongly keep the tab open.
+  const lines = stripAnsi(outputTail.slice(-512)).replace(/\r/g, "\n").split("\n");
+  for (let i = lines.length - 1; i >= 0; i--) {
+    // Drop control bytes (e.g. the BEL bash rings before the banner) and trim.
+    const line = lines[i].replace(/[\x00-\x1f\x7f]/g, "").trim();
+    if (!line) continue;
+    return IDLE_AUTO_LOGOUT_PATTERN.test(line);
+  }
+  return false;
+}
+
 function trackSessionIdlePrompt(session, chunk) {
   if (!session || typeof chunk !== "string" || !chunk) return "";
 
@@ -399,6 +425,7 @@ module.exports = {
   getFreshIdlePrompt,
   isDefaultPowerShellPromptLine,
   trackSessionIdlePrompt,
+  looksLikeIdleAutoLogout,
   isLocalhostHostname,
   extractFirstNonLocalhostUrl,
   normalizeCliPathForPlatform,

electron/bridges/ai/shellUtils.test.cjs

@@ -7,6 +7,7 @@ const {
   getFreshIdlePrompt,
   isDefaultPowerShellPromptLine,
   isPlausibleCliVersionOutput,
+  looksLikeIdleAutoLogout,
   prepareCommandForSpawn,
   trackSessionIdlePrompt,
 } = require("./shellUtils.cjs");
@@ -175,3 +176,64 @@ test("getFreshIdlePrompt and trackSessionIdlePrompt round-trip through a real PT
   // with the cached PS line, so downstream wrapper selection sees "".
   assert.equal(getFreshIdlePrompt(session), "");
 });
+
+test("looksLikeIdleAutoLogout detects the bash TMOUT banner at the tail", () => {
+  // bash prints this immediately before a TMOUT auto-logout exit. The exit
+  // itself is a clean shell exit (code 0, no signal), so the banner is the
+  // only reliable discriminator from a user-typed `exit` (#1062 / #977).
+  assert.equal(
+    looksLikeIdleAutoLogout("user@host:~$ \x07timed out waiting for input: auto-logout\r\n"),
+    true,
+  );
+});
+
+test("looksLikeIdleAutoLogout detects the csh/tcsh auto-logout banner", () => {
+  assert.equal(looksLikeIdleAutoLogout("\r\nauto-logout\r\n"), true);
+});
+
+test("looksLikeIdleAutoLogout sees through ANSI escapes around the banner", () => {
+  assert.equal(
+    looksLikeIdleAutoLogout("\x1b[0m\x1b[33mtimed out waiting for input: auto-logout\x1b[0m\r\n"),
+    true,
+  );
+});
+
+test("looksLikeIdleAutoLogout ignores a plain (non-timeout) logout", () => {
+  // A normal login-shell exit prints "logout" — without the "auto-" prefix —
+  // and must still auto-close the tab.
+  assert.equal(looksLikeIdleAutoLogout("user@host:~$ logout\r\n"), false);
+});
+
+test("looksLikeIdleAutoLogout ignores the banner when it is not at the tail", () => {
+  // "auto-logout" scrolled past long ago; the user then ran more commands and
+  // exited normally. Only the tail end is inspected, so this is not a timeout.
+  const tail = "auto-logout\n" + "x".repeat(400) + "\nuser@host:~$ logout\r\n";
+  assert.equal(looksLikeIdleAutoLogout(tail), false);
+});
+
+test("looksLikeIdleAutoLogout ignores auto-logout in command output before an intentional exit", () => {
+  // Investigating TMOUT: the user greps the profile (output mentions
+  // "auto-logout"), reads it, then exits on purpose. The banner is not the
+  // final line, so the tab must still auto-close. Guards against matching an
+  // unanchored substring anywhere in the recent output.
+  const tail =
+    "root@h:~# grep -i auto-logout /etc/profile\r\n" +
+    "# bash TMOUT auto-logout setting\r\nTMOUT=300\r\n" +
+    "root@h:~# exit\r\nlogout\r\n";
+  assert.equal(looksLikeIdleAutoLogout(tail), false);
+});
+
+test("looksLikeIdleAutoLogout matches the real-server banner shape (prompt + banner on one line)", () => {
+  // The banner can share a line with the trailing prompt after ANSI/control
+  // bytes are stripped (observed over real SSH); anchoring on the line end
+  // must still match.
+  const tail =
+    "\x1b]0;root@VM:~\x07root@VM:~# \x1b[?2004l\x07timed out waiting for input: auto-logout\n";
+  assert.equal(looksLikeIdleAutoLogout(tail), true);
+});
+
+test("looksLikeIdleAutoLogout returns false for empty / non-string input", () => {
+  assert.equal(looksLikeIdleAutoLogout(""), false);
+  assert.equal(looksLikeIdleAutoLogout(undefined), false);
+  assert.equal(looksLikeIdleAutoLogout(null), false);
+});

electron/bridges/cloudSyncBridge.cjs

@@ -98,6 +98,8 @@ const buildS3Client = (config) =>
     region: config.region,
     endpoint: normalizeEndpoint(config.endpoint),
     forcePathStyle: config.forcePathStyle ?? true,
+    requestChecksumCalculation: "WHEN_REQUIRED",
+    responseChecksumValidation: "WHEN_REQUIRED",
     credentials: {
       accessKeyId: config.accessKeyId,
       secretAccessKey: config.secretAccessKey,
@@ -299,4 +301,5 @@ module.exports = {
   // Exposed for tests
   handleWebdavInitialize,
   buildBasicAuthHeader,
+  buildS3Client,
 };

electron/bridges/cloudSyncBridge.s3Checksum.test.cjs

@@ -0,0 +1,25 @@
+const test = require("node:test");
+const assert = require("node:assert/strict");
+
+const {
+  buildS3Client,
+} = require("./cloudSyncBridge.cjs");
+
+const config = {
+  endpoint: "https://s3.example.com",
+  region: "us-east-1",
+  bucket: "netcatty-test",
+  accessKeyId: "access",
+  secretAccessKey: "secret",
+  forcePathStyle: true,
+};
+
+test("S3 client only sends request checksums when required", async () => {
+  const client = buildS3Client(config);
+  assert.equal(await client.config.requestChecksumCalculation(), "WHEN_REQUIRED");
+});
+
+test("S3 client only validates response checksums when required", async () => {
+  const client = buildS3Client(config);
+  assert.equal(await client.config.responseChecksumValidation(), "WHEN_REQUIRED");
+});

electron/bridges/ptyOutputBuffer.cjs

@@ -0,0 +1,63 @@
+"use strict";
+
+/**
+ * Coalescing output buffer for terminal/PTY data on its way to the renderer.
+ *
+ * Incoming shell data is accumulated and delivered to `sendFn` in batches to
+ * keep IPC traffic down, but the batch is flushed on the *next event-loop turn*
+ * (`setImmediate`) rather than after a fixed time interval. A fixed interval
+ * adds that whole interval as latency to interactive echo — every keystroke
+ * round-trips through the buffer and waits out the timer before it can paint.
+ * Turn-based flushing coalesces only the data that has already arrived in the
+ * current turn, so a single echoed keystroke is forwarded almost immediately
+ * while bursts of output still collapse into one send.
+ *
+ * A byte cap still forces an immediate, synchronous flush so a flood of output
+ * can't grow the buffer without bound between turns.
+ *
+ * @param {(data: string) => void} sendFn delivers an accumulated batch
+ * @param {{ maxBufferSize?: number }} [options]
+ * @returns {{ bufferData: (data: string) => void, flush: () => void }}
+ */
+function createPtyOutputBuffer(sendFn, options = {}) {
+  const maxBufferSize = options.maxBufferSize ?? 16384; // 16KB
+
+  let dataBuffer = "";
+  let scheduled = null;
+
+  const cancelScheduled = () => {
+    if (scheduled) {
+      clearImmediate(scheduled);
+      scheduled = null;
+    }
+  };
+
+  const flushNow = () => {
+    scheduled = null;
+    if (dataBuffer.length > 0) {
+      const pending = dataBuffer;
+      dataBuffer = "";
+      sendFn(pending);
+    }
+  };
+
+  const bufferData = (data) => {
+    dataBuffer += data;
+    if (dataBuffer.length >= maxBufferSize) {
+      // Large enough to ship right now — don't wait for the turn flush.
+      cancelScheduled();
+      flushNow();
+    } else if (!scheduled) {
+      scheduled = setImmediate(flushNow);
+    }
+  };
+
+  const flush = () => {
+    cancelScheduled();
+    flushNow();
+  };
+
+  return { bufferData, flush };
+}
+
+module.exports = { createPtyOutputBuffer };

electron/bridges/ptyOutputBuffer.test.cjs

@@ -0,0 +1,90 @@
+const test = require("node:test");
+const assert = require("node:assert/strict");
+
+const { createPtyOutputBuffer } = require("./ptyOutputBuffer.cjs");
+
+/** Resolve after one event-loop turn (immediates have run). */
+const tick = () => new Promise((resolve) => setImmediate(resolve));
+
+test("coalesces data buffered within the same turn into a single send", async () => {
+  const sends = [];
+  const buffer = createPtyOutputBuffer((data) => sends.push(data));
+
+  buffer.bufferData("a");
+  buffer.bufferData("b");
+  buffer.bufferData("c");
+
+  // Nothing is sent synchronously while still in the same turn.
+  assert.equal(sends.length, 0);
+
+  await tick();
+
+  assert.deepEqual(sends, ["abc"]);
+});
+
+test("flushes within a single event-loop turn (not on a fixed delay)", async () => {
+  const sends = [];
+  const buffer = createPtyOutputBuffer((data) => sends.push(data));
+
+  buffer.bufferData("x");
+
+  // A fixed-interval (e.g. 8ms) buffer would NOT have flushed after one
+  // immediate turn. Turn-based flushing must have delivered it by now.
+  await tick();
+
+  assert.deepEqual(sends, ["x"]);
+});
+
+test("flushes immediately and synchronously once the size cap is reached", async () => {
+  const sends = [];
+  const buffer = createPtyOutputBuffer((data) => sends.push(data), {
+    maxBufferSize: 4,
+  });
+
+  buffer.bufferData("ab");
+  assert.equal(sends.length, 0); // under cap, still pending
+
+  buffer.bufferData("cd"); // now "abcd" hits the 4-byte cap
+
+  // Cap flush happens synchronously, without waiting for the turn.
+  assert.deepEqual(sends, ["abcd"]);
+
+  // The pending turn flush must have been cancelled — no empty/duplicate send.
+  await tick();
+  assert.deepEqual(sends, ["abcd"]);
+});
+
+test("flush() forces a synchronous send and cancels the pending turn", async () => {
+  const sends = [];
+  const buffer = createPtyOutputBuffer((data) => sends.push(data));
+
+  buffer.bufferData("hello");
+  buffer.flush();
+
+  assert.deepEqual(sends, ["hello"]);
+
+  await tick();
+  assert.deepEqual(sends, ["hello"]); // not sent twice
+});
+
+test("flush() with an empty buffer does not send", async () => {
+  const sends = [];
+  const buffer = createPtyOutputBuffer((data) => sends.push(data));
+
+  buffer.flush();
+
+  assert.equal(sends.length, 0);
+});
+
+test("keeps batching after a flush", async () => {
+  const sends = [];
+  const buffer = createPtyOutputBuffer((data) => sends.push(data));
+
+  buffer.bufferData("first");
+  await tick();
+
+  buffer.bufferData("second");
+  await tick();
+
+  assert.deepEqual(sends, ["first", "second"]);
+});

electron/bridges/sshAlgorithms.test.cjs

@@ -1,6 +1,8 @@
 const test = require("node:test");
 const assert = require("node:assert/strict");
 const crypto = require("node:crypto");
+const { KexInit, HANDLERS: KEX_HANDLERS } = require("../../node_modules/ssh2/lib/protocol/kex.js");
+const { COMPAT, COMPAT_CHECKS, MESSAGE } = require("../../node_modules/ssh2/lib/protocol/constants.js");
 
 const sshBridge = require("./sshBridge.cjs");
 const sftpBridge = require("./sftpBridge.cjs");
@@ -45,6 +47,81 @@ function withAlgorithmRuntime({ unsupportedGroups = new Set(), hashes = ["sha1",
   }
 }
 
+function kexPayloadFrom(init) {
+  const payload = Buffer.alloc(1 + 16 + init.totalSize + 1 + 4);
+  payload[0] = MESSAGE.KEXINIT;
+  init.copyAllTo(payload, 17);
+  return payload;
+}
+
+function buildKexInit(algorithms) {
+  return new KexInit({
+    kex: algorithms.kex,
+    serverHostKey: algorithms.serverHostKey,
+    cs: {
+      cipher: algorithms.cipher,
+      mac: algorithms.hmac,
+      compress: algorithms.compress,
+      lang: [],
+    },
+    sc: {
+      cipher: algorithms.cipher,
+      mac: algorithms.hmac,
+      compress: algorithms.compress,
+      lang: [],
+    },
+  });
+}
+
+function readLegacyGexRequestBits(compatFlags) {
+  const algorithms = sshBridge.buildAlgorithms(true);
+  const writtenPackets = [];
+  const protocol = {
+    _server: false,
+    _compatFlags: compatFlags,
+    _offer: buildKexInit(algorithms),
+    _debug: undefined,
+    _strictMode: undefined,
+    _kex: undefined,
+    _kexinit: Buffer.from("local-kexinit"),
+    _identRaw: Buffer.from("SSH-2.0-netcatty-test"),
+    _remoteIdentRaw: Buffer.from("SSH-2.0-Comware-5.20"),
+    _packetRW: {
+      write: {
+        allocStartKEX: 0,
+        alloc(size) {
+          return Buffer.alloc(size);
+        },
+        finalize(packet) {
+          return packet;
+        },
+      },
+    },
+    _cipher: {
+      encrypt(packet) {
+        writtenPackets.push(Buffer.from(packet));
+      },
+    },
+  };
+  const remote = buildKexInit({
+    kex: ["diffie-hellman-group-exchange-sha1"],
+    serverHostKey: ["ecdsa-sha2-nistp256", "ssh-rsa"],
+    cipher: ["aes128-ctr"],
+    hmac: ["hmac-sha2-256"],
+    compress: ["none"],
+  });
+
+  KEX_HANDLERS[MESSAGE.KEXINIT](protocol, kexPayloadFrom(remote));
+
+  const request = writtenPackets.find((packet) => packet[0] === MESSAGE.KEXDH_GEX_REQUEST);
+  assert.ok(request, "expected a DH group-exchange request packet");
+  return {
+    min: request.readUInt32BE(1),
+    preferred: request.readUInt32BE(5),
+    max: request.readUInt32BE(9),
+  };
+}
+
 for (const [label, buildAlgorithms] of [
   ["SSH", sshBridge.buildAlgorithms],
   ["SFTP", sftpBridge.buildSftpAlgorithms],
@@ -123,3 +200,17 @@ test("legacy HMAC algorithms skip MD5 when the runtime disables it", () => {
     }
   });
 });
+
+test("Comware legacy group-exchange requests OpenSSH 6.4-sized DH groups", () => {
+  const comwareCompatRule = COMPAT_CHECKS.find(([pattern, flags]) => (
+    pattern instanceof RegExp
+    && pattern.test("Comware-5.20")
+    && (flags & COMPAT.COMWARE_DHGEX_1024)
+  ));
+
+  assert.ok(comwareCompatRule, "Comware servers should opt into the old DH group-exchange request size");
+  assert.deepEqual(
+    readLegacyGexRequestBits(COMPAT.COMWARE_DHGEX_1024),
+    { min: 1024, preferred: 1024, max: 8192 },
+  );
+});

electron/bridges/sshBridge.cjs

@@ -17,6 +17,7 @@ const passphraseHandler = require("./passphraseHandler.cjs");
 const hostKeyVerifier = require("./hostKeyVerifier.cjs");
 const { createProxySocket } = require("./proxyUtils.cjs");
 const { attachX11Forwarding } = require("./x11Forwarding.cjs");
+const { createPtyOutputBuffer } = require("./ptyOutputBuffer.cjs");
 const {
   buildAuthHandler,
   createKeyboardInteractiveHandler,
@@ -33,7 +34,7 @@ const {
   isPassphraseCancelledError,
 } = require("./sshAuthHelper.cjs");
 const sessionLogStreamManager = require("./sessionLogStreamManager.cjs");
-const { trackSessionIdlePrompt } = require("./ai/shellUtils.cjs");
+const { trackSessionIdlePrompt, looksLikeIdleAutoLogout } = require("./ai/shellUtils.cjs");
 const { createZmodemSentry } = require("./zmodemHelper.cjs");
 const {
   buildAlgorithms,
@@ -365,6 +366,8 @@ function resolveLangFromCharset(charset) {
 
 const { safeSend } = require("./ipcUtils.cjs");
 
+const zmodemOverwritePending = new Map(); // requestId -> (decision) => void
+
 /**
  * Initialize the SSH bridge with dependencies
  */
@@ -1285,35 +1288,14 @@ async function startSSHSession(event, options) {
               });
             }
 
-            // Data buffering for reduced IPC overhead
-            let dataBuffer = '';
-            let flushTimeout = null;
-            const FLUSH_INTERVAL = 8; // ms - flush every 8ms for ~120fps equivalent
-            const MAX_BUFFER_SIZE = 16384; // 16KB - flush immediately if buffer gets too large
-
-            const flushBuffer = () => {
-              if (dataBuffer.length > 0) {
-                const contents = event.sender;
-                safeSend(contents, "netcatty:data", { sessionId, data: dataBuffer });
-                dataBuffer = '';
-              }
-              flushTimeout = null;
-            };
-
-            const bufferData = (data) => {
-              dataBuffer += data;
-              // Immediate flush for large chunks
-              if (dataBuffer.length >= MAX_BUFFER_SIZE) {
-                if (flushTimeout) {
-                  clearTimeout(flushTimeout);
-                  flushTimeout = null;
-                }
-                flushBuffer();
-              } else if (!flushTimeout) {
-                // Schedule flush
-                flushTimeout = setTimeout(flushBuffer, FLUSH_INTERVAL);
-              }
-            };
+            // Coalesce shell output and deliver it to the renderer on the next
+            // event-loop turn (see ptyOutputBuffer) rather than on a fixed timer,
+            // so interactive echo isn't held back by the batch interval. A size
+            // cap still forces an immediate flush for bursts of output.
+            const { bufferData, flush: flushBuffer } = createPtyOutputBuffer((data) => {
+              const contents = event.sender;
+              safeSend(contents, "netcatty:data", { sessionId, data });
+            });
 
             const sshZmodemSentry = createZmodemSentry({
               sessionId,
@@ -1330,6 +1312,31 @@ async function startSSHSession(event, options) {
               interruptRemote() {
                 try { stream.signal?.("INT"); } catch { /* ignore */ }
               },
+              probeReceiveConflicts(names) {
+                return probeReceiveConflicts(sessions.get(sessionId), names);
+              },
+              removeRemoteFiles(paths) {
+                return removeRemoteFiles(sessions.get(sessionId), paths);
+              },
+              restoreRemoteModes(entries) {
+                return restoreRemoteModes(sessions.get(sessionId), entries);
+              },
+              requestOverwriteDecision(filename) {
+                return new Promise((resolve) => {
+                  const requestId = randomUUID();
+                  const timer = setTimeout(() => {
+                    zmodemOverwritePending.delete(requestId);
+                    resolve({ action: "skip", applyToRest: false });
+                  }, 120000);
+                  zmodemOverwritePending.set(requestId, (payload) => {
+                    clearTimeout(timer);
+                    resolve({ action: payload.action, applyToRest: !!payload.applyToRest });
+                  });
+                  safeSend(event.sender, "netcatty:zmodem:overwrite-request", {
+                    sessionId, requestId, filename,
+                  });
+                });
+              },
               getWebContents() {
                 return event.sender;
               },
@@ -1365,10 +1372,8 @@ async function startSSHSession(event, options) {
             });
 
             stream.on("close", () => {
-              // Always flush buffered data regardless of session state
-              if (flushTimeout) {
-                clearTimeout(flushTimeout);
-              }
+              // Always flush buffered data regardless of session state.
+              // flushBuffer() cancels any pending scheduled flush internally.
               flushBuffer();
               sessionLogStreamManager.stopStream(sessionId, logStreamToken);
               if (detachX11Forwarding) {
@@ -1386,7 +1391,14 @@ async function startSSHSession(event, options) {
                 if (transportError) {
                   safeSend(contents, "netcatty:exit", { sessionId, exitCode: 1, error: transportError, reason: "error" });
                 } else {
-                  safeSend(contents, "netcatty:exit", { sessionId, exitCode: streamExitCode, reason: streamExited ? "exited" : "closed" });
+                  // A shell TMOUT auto-logout is a clean exit (numeric code, no
+                  // signal) — identical to a user-typed `exit` by code/signal —
+                  // so detect it via the banner the shell prints just before
+                  // exiting and report it as a timeout. That keeps the tab open
+                  // for reconnect instead of auto-closing it (#1062 / #977).
+                  const idleTimedOut = streamExited && looksLikeIdleAutoLogout(session?._promptTrackTail);
+                  const reason = idleTimedOut ? "timeout" : (streamExited ? "exited" : "closed");
+                  safeSend(contents, "netcatty:exit", { sessionId, exitCode: streamExitCode, reason });
                 }
                 sessions.get(sessionId)?.zmodemSentry?.cancel();
                 sessions.delete(sessionId);
@@ -2012,24 +2024,58 @@ async function getSessionPwd(event, payload) {
     // so sh keeps the same PID and $PPID = sshd. Starting another shell
     // without exec would make $PPID point at the intermediate shell instead.
     const posixScript = `SELF=$$
-find_child_shell() {
-  mode=$2
-  ps -e -o pid=,ppid=,stat=,comm= 2>/dev/null | awk -v pp="$1" -v self="$SELF" -v mode="$mode" '
-    $1 != self && $2 == pp && $4 ~ /^(ba|z|fi|k|da)?sh$/ {
-      if (index($3, "+") > 0) { print $1; found=1; exit }
-      if (mode != "foreground" && pid == "") pid=$1
+# Find the interactive shell child of this exec channel's sshd ($PPID).
+# Prefer the one attached to a controlling tty (the user's shell): probe exec
+# channels like this one have no tty ("?"), and ps output is unsorted, so
+# without the tty preference a concurrent probe's shell could be picked when
+# several exist under the same sshd (#1065 review). Falls back to any shell
+# child if none has a tty.
+find_login_shell() {
+  ps -e -o pid=,ppid=,tty=,comm= 2>/dev/null | awk -v pp="$1" -v self="$SELF" '
+    $1 != self && $2 == pp && $4 ~ /^-?(ba|z|fi|k|da|a)?sh$/ {
+      if ($3 != "?") { print $1; found=1; exit }
+      if (any == "") any=$1
     }
-    END { if (!found && mode != "foreground" && pid != "") print pid }
+    END { if (!found && any != "") print any }
   '
 }
-pid=$(find_child_shell "$PPID" any)
-while [ -n "$pid" ]; do
-  child=$(find_child_shell "$pid" foreground)
-  [ -n "$child" ] || break
-  pid="$child"
-done
-if [ -n "$pid" ]; then
+# From the login shell, pick the DEEPEST foreground shell in its process
+# subtree. "Foreground" = the controlling tty's foreground process group ("+"
+# in stat), i.e. the shell the user is actually typing in. Walking the whole
+# subtree (rather than only direct shell children) lets us follow through
+# non-shell foreground parents like su / sudo, so we read the cwd of the
+# su'd / sudo'd shell instead of stopping at the login shell (#1065). Falls
+# back to the login shell when no foreground shell is found.
+find_active_shell() {
+  ps -e -o pid=,ppid=,stat=,comm= 2>/dev/null | awk -v start="$1" '
+    { pp[$1]=$2; st[$1]=$3; cm[$1]=$4; ord[NR]=$1 }
+    function isshell(c) { return c ~ /^-?(ba|z|fi|k|da|a)?sh$/ }
+    function depth(p,   d) { d=0; while (p != "" && d < 64) { if (p == start) return d; p=pp[p]; d++ } return -1 }
+    END {
+      best=-1; bp="";
+      for (i=1; i<=NR; i++) {
+        p=ord[i];
+        if (!isshell(cm[p])) continue;
+        if (index(st[p], "+") == 0) continue;
+        d=depth(p); if (d < 0) continue;
+        if (d > best) { best=d; bp=p }
+      }
+      print (bp != "" ? bp : start)
+    }
+  '
+}
+login=$(find_login_shell "$PPID")
+if [ -n "$login" ]; then
+  pid=$(find_active_shell "$login")
+  [ -n "$pid" ] || pid="$login"
   cwd=$(readlink /proc/$pid/cwd 2>/dev/null)
+  # /proc/<pid>/cwd is only readable for same-uid processes (ptrace perms), so
+  # this unprivileged exec channel cannot read a su'd / sudo'd shell owned by
+  # another user. Fall back to the same-uid login shell's cwd before giving up
+  # to the home directory (#1065 review).
+  if [ -z "$cwd" ] && [ "$pid" != "$login" ]; then
+    cwd=$(readlink /proc/$login/cwd 2>/dev/null)
+  fi
   [ -n "$cwd" ] && printf '%s\\n' "$cwd" && exit 0
 fi
 emit_home() {
@@ -2077,6 +2123,103 @@ exit 1`;
   });
 }
 
+// Resolve the directory the running `rz` writes to (its own cwd) and report
+// which of `names` already exist there. Returns { dir, existing } or null.
+function probeReceiveConflicts(session, names) {
+  return new Promise((resolve) => {
+    if (!session || !session.conn || !Array.isArray(names) || names.length === 0) {
+      return resolve(null);
+    }
+    const timer = setTimeout(() => resolve(null), 5000);
+    const script = `SELF=$$
+find_login_shell() {
+  ps -e -o pid=,ppid=,tty=,comm= 2>/dev/null | awk -v pp="$1" -v self="$SELF" '
+    $1 != self && $2 == pp && $4 ~ /^-?(ba|z|fi|k|da|a)?sh$/ {
+      if ($3 != "?") { print $1; found=1; exit }
+      if (any == "") any=$1
+    }
+    END { if (!found && any != "") print any }'
+}
+find_fg_leaf() {
+  ps -e -o pid=,ppid=,stat=,comm= 2>/dev/null | awk -v start="$1" '
+    { pp[$1]=$2; st[$1]=$3; ord[NR]=$1 }
+    function depth(p,  d){ d=0; while(p!="" && d<64){ if(p==start) return d; p=pp[p]; d++ } return -1 }
+    END { best=-1; bp=""; for(i=1;i<=NR;i++){ p=ord[i];
+      if(index(st[p],"+")==0) continue; d=depth(p); if(d<0) continue;
+      if(d>best){best=d; bp=p} } print bp }'
+}
+login=$(find_login_shell "$PPID")
+[ -n "$login" ] || exit 0
+leaf=$(find_fg_leaf "$login")
+[ -n "$leaf" ] || leaf="$login"
+dir=$(readlink /proc/$leaf/cwd 2>/dev/null)
+[ -n "$dir" ] || exit 0
+printf 'DIR\\t%s\\n' "$dir"
+cd "$dir" 2>/dev/null || exit 0
+for n in "$@"; do
+  [ -e "$n" ] || continue
+  m=$(stat -c %a -- "$n" 2>/dev/null || stat -f %Lp -- "$n" 2>/dev/null)
+  printf 'EXIST\\t%s\\t%s\\n' "$n" "$m"
+done`;
+    const argv = names.map((n) => quoteShellArg(n)).join(" ");
+    const cmd = `exec sh -c ${quoteShellArg(script)} sh ${argv}`;
+    session.conn.exec(cmd, (err, stream) => {
+      if (err) { clearTimeout(timer); return resolve(null); }
+      let out = "";
+      stream.on("data", (d) => { out += d.toString(); });
+      stream.on("close", () => {
+        clearTimeout(timer);
+        let dir = null; const existing = []; const modes = {};
+        for (const line of out.split("\n")) {
+          const [tag, val, mode] = line.split("\t");
+          if (tag === "DIR") dir = val;
+          else if (tag === "EXIST" && val) {
+            existing.push(val);
+            if (mode && /^[0-7]{3,4}$/.test(mode)) modes[val] = mode;
+          }
+        }
+        resolve(dir ? { dir, existing, modes } : null);
+      });
+    });
+  });
+}
+
+// rm -f the given absolute remote paths (quoted; injection-safe).
+function removeRemoteFiles(session, paths) {
+  return new Promise((resolve) => {
+    if (!session || !session.conn || !Array.isArray(paths) || paths.length === 0) return resolve();
+    const argv = paths.map((p) => quoteShellArg(p)).join(" ");
+    const timer = setTimeout(resolve, 5000);
+    session.conn.exec(`exec sh -c 'rm -f -- "$@"' sh ${argv}`, (err, stream) => {
+      if (err) { clearTimeout(timer); return resolve(); }
+      stream.on("data", () => {}); stream.stderr?.on("data", () => {});
+      stream.on("close", () => { clearTimeout(timer); resolve(); });
+    });
+  });
+}
+
+// chmod the given { path, mode } entries back to their captured permissions
+// (parameterized; injection-safe). Modes are validated octal before use.
+function restoreRemoteModes(session, entries) {
+  return new Promise((resolve) => {
+    if (!session || !session.conn || !Array.isArray(entries) || entries.length === 0) return resolve();
+    const args = [];
+    for (const e of entries) {
+      if (!e || !e.path || !/^[0-7]{3,4}$/.test(String(e.mode))) continue;
+      args.push(quoteShellArg(String(e.mode)));
+      args.push(quoteShellArg(e.path));
+    }
+    if (args.length === 0) return resolve();
+    const timer = setTimeout(resolve, 5000);
+    const script = 'while [ "$#" -ge 2 ]; do chmod "$1" "$2" 2>/dev/null; shift 2; done';
+    session.conn.exec(`exec sh -c ${quoteShellArg(script)} sh ${args.join(" ")}`, (err, stream) => {
+      if (err) { clearTimeout(timer); return resolve(); }
+      stream.on("data", () => {}); stream.stderr?.on("data", () => {});
+      stream.on("close", () => { clearTimeout(timer); resolve(); });
+    });
+  });
+}
+
 /**
  * List directory contents on remote machine for path autocomplete.
  * Uses a separate exec channel — does not touch the interactive shell.
@@ -2653,6 +2796,10 @@ function registerHandlers(ipcMain) {
     }
     return keys;
   });
+  ipcMain.on("netcatty:zmodem:overwrite-response", (_event, payload) => {
+    const resolve = zmodemOverwritePending.get(payload?.requestId);
+    if (resolve) { zmodemOverwritePending.delete(payload.requestId); resolve(payload); }
+  });
   // Register the shared keyboard-interactive response handler
   keyboardInteractiveHandler.registerHandler(ipcMain);
   // Register the passphrase response handler

electron/bridges/sshBridge.execCommandPassphrase.test.cjs

@@ -81,6 +81,7 @@ test("execCommand stops when an identity file passphrase prompt is cancelled", a
     handle(channel, handler) {
       this.handlers.set(channel, handler);
     },
+    on() {},
   };
   bridge.registerHandlers(ipcMain);
   const execHandler = ipcMain.handlers.get("netcatty:ssh:exec");

electron/bridges/terminalBridge.cjs

@@ -25,6 +25,7 @@ const moshHandshake = require("./moshHandshake.cjs");
 const tempDirBridge = require("./tempDirBridge.cjs");
 const { createTelnetAutoLogin } = require("./telnetAutoLogin.cjs");
 const telnetProtocol = require("./telnetProtocol.cjs");
+const { createPtyOutputBuffer } = require("./ptyOutputBuffer.cjs");
 
 const execFileAsync = promisify(execFile);
 
@@ -80,51 +81,6 @@ function init(deps) {
   electronModule = deps.electronModule;
 }
 
-/**
- * Create an 8ms/16KB PTY data buffer for reduced IPC overhead.
- * Mirrors the SSH stream buffering strategy in sshBridge.cjs.
- * @param {Function} sendFn - called with the accumulated string to deliver
- * @returns {{ bufferData: (data: string) => void, flush: () => void }}
- */
-function createPtyBuffer(sendFn) {
-  const FLUSH_INTERVAL = 8;      // ms - flush every 8ms (~120fps equivalent)
-  const MAX_BUFFER_SIZE = 16384; // 16KB - flush immediately if buffer grows too large
-
-  let dataBuffer = '';
-  let flushTimeout = null;
-
-  const flushBuffer = () => {
-    if (dataBuffer.length > 0) {
-      sendFn(dataBuffer);
-      dataBuffer = '';
-    }
-    flushTimeout = null;
-  };
-
-  const flush = () => {
-    if (flushTimeout) {
-      clearTimeout(flushTimeout);
-      flushTimeout = null;
-    }
-    flushBuffer();
-  };
-
-  const bufferData = (data) => {
-    dataBuffer += data;
-    if (dataBuffer.length >= MAX_BUFFER_SIZE) {
-      if (flushTimeout) {
-        clearTimeout(flushTimeout);
-        flushTimeout = null;
-      }
-      flushBuffer();
-    } else if (!flushTimeout) {
-      flushTimeout = setTimeout(flushBuffer, FLUSH_INTERVAL);
-    }
-  };
-
-  return { bufferData, flush };
-}
-
 /**
  * Locate an executable on POSIX systems by name.
  *
@@ -454,7 +410,7 @@ function startLocalSession(event, payload) {
     });
   }
 
-  const { bufferData: bufferLocalData, flush: flushLocal } = createPtyBuffer((data) => {
+  const { bufferData: bufferLocalData, flush: flushLocal } = createPtyOutputBuffer((data) => {
     const contents = electronModule.webContents.fromId(session.webContentsId);
     contents?.send("netcatty:data", { sessionId, data });
   });
@@ -662,7 +618,7 @@ async function startTelnetSession(event, options) {
     const telnetDecoderRef = { current: iconv.getDecoder(initialTelnetEncoding) };
 
     const telnetWebContentsId = event.sender.id;
-    const { bufferData: bufferTelnetData, flush: flushTelnet } = createPtyBuffer((data) => {
+    const { bufferData: bufferTelnetData, flush: flushTelnet } = createPtyOutputBuffer((data) => {
       const contents = electronModule.webContents.fromId(telnetWebContentsId);
       contents?.send("netcatty:data", { sessionId, data });
     });
@@ -1189,7 +1145,7 @@ async function startMoshSessionViaHandshake(event, options, { bareClient, sshExe
   // it to scope its stopStream call.
   session.logStreamToken = logStreamToken;
 
-  const { bufferData, flush } = createPtyBuffer((data) => {
+  const { bufferData, flush } = createPtyOutputBuffer((data) => {
     const contents = electronModule.webContents.fromId(session.webContentsId);
     contents?.send("netcatty:data", { sessionId, data });
   });
@@ -1593,6 +1549,31 @@ function writeToSession(event, payload) {
   }
 }
 
+/**
+ * Pause or resume a session's source stream for output back-pressure.
+ * The renderer asks for this when its write backlog crosses a watermark, so a
+ * flooding source can't outrun the terminal renderer. Works across session
+ * kinds: ssh2 channel (stream), node-pty (proc), telnet socket, serial port —
+ * all expose pause()/resume().
+ */
+function setSessionFlowPaused(event, payload) {
+  const session = sessions.get(payload.sessionId);
+  if (!session) return;
+  const target = session.stream || session.proc || session.socket || session.serialPort;
+  if (!target) return;
+  try {
+    if (payload.paused) {
+      target.pause?.();
+    } else {
+      target.resume?.();
+    }
+  } catch (err) {
+    if (err?.code !== 'EPIPE' && err?.code !== 'ERR_STREAM_DESTROYED') {
+      console.warn("Flow control toggle failed", err);
+    }
+  }
+}
+
 /**
  * Resize a session terminal
  */
@@ -1707,6 +1688,7 @@ function registerHandlers(ipcMain) {
   ipcMain.handle("netcatty:terminal:setEncoding", setSessionEncoding);
   ipcMain.on("netcatty:write", writeToSession);
   ipcMain.on("netcatty:resize", resizeSession);
+  ipcMain.on("netcatty:flow", setSessionFlowPaused);
   ipcMain.on("netcatty:close", closeSession);
 }
 
@@ -1892,6 +1874,7 @@ module.exports = {
   listSerialPorts,
   writeToSession,
   resizeSession,
+  setSessionFlowPaused,
   closeSession,
   cleanupAllSessions,
   getDefaultShell,

electron/bridges/zmodemHelper.cjs

@@ -20,6 +20,58 @@ function getElectron() {
   return _electron;
 }
 
+/**
+ * Resolve per-file overwrite choices into an upload plan. Pure (no I/O):
+ * `resolveDecision(name)` is awaited only for files in `existingList`, in input
+ * order; `{ applyToRest: true }` reuses that action for the remaining conflicts.
+ * Returns indices into the original `names` array so callers preserve per-file
+ * identity even when two files share a basename.
+ * Actions: 'overwrite' (rm remote then send), 'skip' (don't send), 'cancel' (abort all).
+ */
+async function buildUploadPlan(names, existingList, resolveDecision) {
+  const existing = new Set(existingList);
+  const offerIndices = [];
+  const removeIndices = [];
+  let bulkAction = null;
+  for (let idx = 0; idx < names.length; idx++) {
+    const name = names[idx];
+    if (!existing.has(name)) { offerIndices.push(idx); continue; }
+    let action = bulkAction;
+    if (!action) {
+      const decision = (await resolveDecision(name)) || { action: "skip" };
+      action = decision.action;
+      if (decision.applyToRest && action !== "cancel") bulkAction = action;
+    }
+    if (action === "cancel") return { offerIndices: [], removeIndices: [], aborted: true };
+    if (action === "overwrite") { removeIndices.push(idx); offerIndices.push(idx); }
+    // 'skip' → omit from both
+  }
+  return { offerIndices, removeIndices, aborted: false };
+}
+
+/**
+ * Resolve which overwritten files need their original mode restored after rz
+ * re-creates them. rz writes new files with the remote umask, dropping the
+ * prior permission bits (issue #1079). Pure: returns absolute `{ path, mode }`
+ * entries for the overwritten files, skipping any whose mode wasn't captured
+ * and de-duplicating shared basenames.
+ */
+function buildModeRestores(dir, names, removeIndices, modes) {
+  const base = String(dir).replace(/\/+$/, "");
+  const seen = new Set();
+  const restores = [];
+  for (const i of removeIndices) {
+    const name = names[i];
+    const mode = modes && modes[name];
+    if (!mode) continue;
+    const target = `${base}/${name}`;
+    if (seen.has(target)) continue;
+    seen.add(target);
+    restores.push({ path: target, mode });
+  }
+  return restores;
+}
+
 /**
  * Create a ZMODEM sentry that wraps a session's data stream.
  *
@@ -524,10 +576,45 @@ async function handleUpload(zsession, opts) {
   const filePaths = result.filePaths;
   const fileStats = filePaths.map((fp) => fs.statSync(fp));
 
-  for (let i = 0; i < filePaths.length; i++) {
-    const filePath = filePaths[i];
-    const stat = fileStats[i];
-    const name = path.basename(filePath);
+  const allNames = filePaths.map((fp) => path.basename(fp));
+
+  // Conflict handling (SSH only — callbacks absent on local/telnet/serial).
+  // On any failure we fall back to today's behavior (rz silently skips).
+  let plan = { offerIndices: allNames.map((_, i) => i), removeIndices: [], aborted: false };
+  let probeDir = null;
+  let probeModes = null;
+  if (opts.probeReceiveConflicts && opts.requestOverwriteDecision) {
+    try {
+      const probe = await opts.probeReceiveConflicts(allNames);
+      if (probe && probe.dir && Array.isArray(probe.existing) && probe.existing.length > 0) {
+        probeDir = probe.dir;
+        probeModes = probe.modes || {};
+        plan = await buildUploadPlan(allNames, probe.existing, opts.requestOverwriteDecision);
+        if (plan.aborted) {
+          try { zsession.abort(); } catch { /* ignore */ }
+          abortRemoteProcess(opts.writeToRemote);
+          throw new Error("Transfer cancelled");
+        }
+        if (plan.removeIndices.length && opts.removeRemoteFiles) {
+          const base = probe.dir.replace(/\/+$/, "");
+          const targets = [...new Set(plan.removeIndices.map((i) => `${base}/${allNames[i]}`))];
+          try {
+            await opts.removeRemoteFiles(targets);
+          } catch (err) {
+            console.warn("[ZMODEM] removeRemoteFiles failed; rz will skip:", err?.message || err);
+          }
+        }
+      }
+    } catch (err) {
+      if (err instanceof Error && err.message === "Transfer cancelled") throw err;
+      console.warn("[ZMODEM] conflict probe failed; proceeding:", err?.message || err);
+    }
+  }
+
+  const offers = plan.offerIndices.map((i) => ({ filePath: filePaths[i], stat: fileStats[i], name: allNames[i] }));
+
+  for (let i = 0; i < offers.length; i++) {
+    const { filePath, stat, name } = offers[i];
 
     safeSend(contents, "netcatty:zmodem:progress", {
       sessionId,
@@ -535,18 +622,18 @@ async function handleUpload(zsession, opts) {
       transferred: 0,
       total: stat.size,
       fileIndex: i,
-      fileCount: filePaths.length,
+      fileCount: offers.length,
       transferType: "upload",
     });
 
     let bytesRemaining = 0;
-    for (let j = i; j < fileStats.length; j++) bytesRemaining += fileStats[j].size;
+    for (let j = i; j < offers.length; j++) bytesRemaining += offers[j].stat.size;
 
     const xfer = await zsession.send_offer({
       name,
       size: stat.size,
       mtime: new Date(stat.mtimeMs),
-      files_remaining: filePaths.length - i,
+      files_remaining: offers.length - i,
       bytes_remaining: bytesRemaining,
     });
 
@@ -579,7 +666,7 @@ async function handleUpload(zsession, opts) {
           transferred: sent,
           total: stat.size,
           fileIndex: i,
-          fileCount: filePaths.length,
+          fileCount: offers.length,
           transferType: "upload",
         });
 
@@ -597,7 +684,7 @@ async function handleUpload(zsession, opts) {
         transferred: stat.size,
         total: stat.size,
         fileIndex: i,
-        fileCount: filePaths.length,
+        fileCount: offers.length,
         transferType: "upload",
         finalizing: true,
       });
@@ -608,6 +695,20 @@ async function handleUpload(zsession, opts) {
   }
 
   await withTimeout(zsession.close(), 120000);
+
+  // rz re-creates overwritten files with the remote umask, dropping their
+  // original permission bits. Now that everything is on disk, restore them
+  // to the modes captured before the rm (issue #1079).
+  if (plan.removeIndices.length && probeDir && opts.restoreRemoteModes) {
+    const restores = buildModeRestores(probeDir, allNames, plan.removeIndices, probeModes);
+    if (restores.length) {
+      try {
+        await opts.restoreRemoteModes(restores);
+      } catch (err) {
+        console.warn("[ZMODEM] restoreRemoteModes failed:", err?.message || err);
+      }
+    }
+  }
 }
 
 /**
@@ -791,4 +892,4 @@ function safeSend(contents, channel, data) {
   }
 }
 
-module.exports = { createZmodemSentry };
+module.exports = { createZmodemSentry, buildUploadPlan, buildModeRestores };

electron/bridges/zmodemHelper.test.cjs

@@ -0,0 +1,74 @@
+const test = require("node:test");
+const assert = require("node:assert/strict");
+const { buildUploadPlan, buildModeRestores } = require("./zmodemHelper.cjs");
+
+const never = () => { throw new Error("resolver should not be called"); };
+
+test("no conflicts: all indices offered, none removed, resolver untouched", async () => {
+  const plan = await buildUploadPlan(["a.txt", "b.txt"], [], never);
+  assert.deepEqual(plan, { offerIndices: [0, 1], removeIndices: [], aborted: false });
+});
+
+test("overwrite a conflict: index both removed and offered", async () => {
+  const plan = await buildUploadPlan(["a.txt", "b.txt"], ["b.txt"], async () => ({ action: "overwrite" }));
+  assert.deepEqual(plan, { offerIndices: [0, 1], removeIndices: [1], aborted: false });
+});
+
+test("skip a conflict: index omitted from offer and remove", async () => {
+  const plan = await buildUploadPlan(["a.txt", "b.txt"], ["b.txt"], async () => ({ action: "skip" }));
+  assert.deepEqual(plan, { offerIndices: [0], removeIndices: [], aborted: false });
+});
+
+test("cancel aborts the whole transfer", async () => {
+  const plan = await buildUploadPlan(["a.txt", "b.txt"], ["b.txt"], async () => ({ action: "cancel" }));
+  assert.deepEqual(plan, { offerIndices: [], removeIndices: [], aborted: true });
+});
+
+test("applyToRest reuses the action and stops prompting", async () => {
+  let calls = 0;
+  const plan = await buildUploadPlan(["a", "b", "c"], ["a", "b", "c"],
+    async () => { calls++; return { action: "overwrite", applyToRest: true }; });
+  assert.equal(calls, 1);
+  assert.deepEqual(plan, { offerIndices: [0, 1, 2], removeIndices: [0, 1, 2], aborted: false });
+});
+
+test("only conflicting files invoke the resolver; order preserved", async () => {
+  const seen = [];
+  const plan = await buildUploadPlan(["a", "b", "c"], ["b"],
+    async (n) => { seen.push(n); return { action: "skip" }; });
+  assert.deepEqual(seen, ["b"]);
+  assert.deepEqual(plan.offerIndices, [0, 2]);
+});
+
+test("duplicate basenames keep independent per-file decisions", async () => {
+  // Two different local files share a basename; skip the first, overwrite the second.
+  const actions = ["skip", "overwrite"];
+  let i = 0;
+  const plan = await buildUploadPlan(["x.txt", "x.txt"], ["x.txt"],
+    async () => ({ action: actions[i++] }));
+  assert.deepEqual(plan, { offerIndices: [1], removeIndices: [1], aborted: false });
+});
+
+// Issue #1079: overwriting (rm + rz re-create) drops the original permission
+// bits. buildModeRestores resolves which overwritten files to chmod back.
+
+test("buildModeRestores maps overwritten files to their captured modes", () => {
+  assert.deepEqual(
+    buildModeRestores("/home/u", ["a.sh", "b.txt"], [0], { "a.sh": "755" }),
+    [{ path: "/home/u/a.sh", mode: "755" }],
+  );
+});
+
+test("buildModeRestores skips files whose mode was not captured", () => {
+  assert.deepEqual(
+    buildModeRestores("/srv", ["a", "b"], [0, 1], { a: "644" }),
+    [{ path: "/srv/a", mode: "644" }],
+  );
+});
+
+test("buildModeRestores strips trailing slashes and dedupes duplicate basenames", () => {
+  assert.deepEqual(
+    buildModeRestores("/srv//", ["x", "x"], [0, 1], { x: "600" }),
+    [{ path: "/srv/x", mode: "600" }],
+  );
+});

electron/preload.cjs

@@ -10,6 +10,7 @@ const transferErrorListeners = new Map();
 const transferCancelledListeners = new Map();
 const chainProgressListeners = new Map();
 const zmodemListeners = new Map();
+const zmodemOverwriteListeners = new Map(); // sessionId -> Set<cb>
 const sftpConnectionProgressListeners = new Set();
 const authFailedListeners = new Map();
 const telnetAutoLoginCompleteListeners = new Map();
@@ -137,6 +138,10 @@ ipcRenderer.on("netcatty:zmodem:error", (_event, payload) => {
   if (!set) return;
   set.forEach((cb) => { try { cb({ type: "error", ...payload }); } catch {} });
 });
+ipcRenderer.on("netcatty:zmodem:overwrite-request", (_event, payload) => {
+  const set = zmodemOverwriteListeners.get(payload.sessionId);
+  if (set) set.forEach((cb) => cb(payload));
+});
 
 ipcRenderer.on("netcatty:data", (_event, payload) => {
   const set = dataListeners.get(payload.sessionId);
@@ -185,6 +190,7 @@ ipcRenderer.on("netcatty:exit", (_event, payload) => {
   telnetAutoLoginCompleteListeners.delete(payload.sessionId);
   telnetAutoLoginCancelledListeners.delete(payload.sessionId);
   zmodemListeners.delete(payload.sessionId);
+  zmodemOverwriteListeners.delete(payload.sessionId);
   const pendingTimer = _mcpFlushTimers.get(payload.sessionId);
   if (pendingTimer) {
     clearTimeout(pendingTimer);
@@ -663,6 +669,9 @@ const api = {
   resizeSession: (sessionId, cols, rows) => {
     ipcRenderer.send("netcatty:resize", { sessionId, cols, rows });
   },
+  setSessionFlowPaused: (sessionId, paused) => {
+    ipcRenderer.send("netcatty:flow", { sessionId, paused: Boolean(paused) });
+  },
   closeSession: (sessionId) => {
     ipcRenderer.send("netcatty:close", { sessionId });
   },
@@ -682,6 +691,14 @@ const api = {
   cancelZmodem: (sessionId) => {
     ipcRenderer.send("netcatty:zmodem:cancel", { sessionId });
   },
+  onZmodemOverwriteRequest: (sessionId, cb) => {
+    if (!zmodemOverwriteListeners.has(sessionId)) zmodemOverwriteListeners.set(sessionId, new Set());
+    zmodemOverwriteListeners.get(sessionId).add(cb);
+    return () => zmodemOverwriteListeners.get(sessionId)?.delete(cb);
+  },
+  respondZmodemOverwrite: (payload) => {
+    ipcRenderer.send("netcatty:zmodem:overwrite-response", payload);
+  },
   onSessionData: (sessionId, cb) => {
     if (!dataListeners.has(sessionId)) dataListeners.set(sessionId, new Set());
     dataListeners.get(sessionId).add(cb);

eslint.config.js

@@ -3,11 +3,16 @@ import tsParser from "@typescript-eslint/parser";
 import tsPlugin from "@typescript-eslint/eslint-plugin";
 import unusedImports from "eslint-plugin-unused-imports";
 import reactHooks from "eslint-plugin-react-hooks";
+import globals from "globals";
 
 export default [
-  js.configs.recommended,
+  // The recommended preset has no file scope of its own, so scope it off all of
+  // electron/ — that main-process tree is historically unlinted. The bridges
+  // get a focused rule set in the dedicated block at the end of this config;
+  // every other electron/ file matches no config and stays unlinted as before.
+  { ...js.configs.recommended, ignores: ["electron/**"] },
   {
-    ignores: ["node_modules/**", "dist/**", "electron/**", "scripts/**", "public/monaco/**", ".github/**", ".claude/**", "release/**", ".worktrees/**"],
+    ignores: ["node_modules/**", "dist/**", "scripts/**", "public/monaco/**", ".github/**", ".claude/**", "release/**", ".worktrees/**"],
   },
   {
     files: ["**/*.{ts,tsx}"],
@@ -168,4 +173,26 @@ export default [
       ],
     },
   },
+  {
+    // Electron main-process bridges are CommonJS and were historically excluded
+    // from linting. Lint them for undefined references only — the cheap,
+    // high-value guard against e.g. a removed variable still referenced
+    // elsewhere. (The TS config disables no-undef because the type-checker
+    // already covers it there; these .cjs files have no such safety net.)
+    files: ["electron/bridges/**/*.cjs"],
+    languageOptions: {
+      ecmaVersion: "latest",
+      sourceType: "commonjs",
+      globals: globals.node,
+    },
+    linterOptions: {
+      // Only no-undef is enabled here, so pre-existing eslint-disable comments
+      // for other rules (no-console, no-control-regex, …) would all report as
+      // "unused". Don't flag them — they stay valid for future rule additions.
+      reportUnusedDisableDirectives: "off",
+    },
+    rules: {
+      "no-undef": "error",
+    },
+  },
 ];

global.d.ts

@@ -323,6 +323,7 @@ declare global {
     setSessionEncoding?(sessionId: string, encoding: string): Promise<{ ok: boolean; encoding: string }>;
     writeToSession(sessionId: string, data: string, options?: { automated?: boolean }): void;
     resizeSession(sessionId: string, cols: number, rows: number): void;
+    setSessionFlowPaused(sessionId: string, paused: boolean): void;
     closeSession(sessionId: string): void;
     // ZMODEM file transfer
     onZmodemEvent?(
@@ -341,6 +342,15 @@ declare global {
       }) => void
     ): () => void;
     cancelZmodem?(sessionId: string): void;
+    onZmodemOverwriteRequest?(
+      sessionId: string,
+      cb: (payload: { sessionId: string; requestId: string; filename: string }) => void
+    ): () => void;
+    respondZmodemOverwrite?(payload: {
+      requestId: string;
+      action: "overwrite" | "skip" | "cancel";
+      applyToRest: boolean;
+    }): void;
     onSessionData(sessionId: string, cb: (data: string) => void): () => void;
     onSessionExit(
       sessionId: string,

infrastructure/services/adapters/S3Adapter.ts

@@ -194,6 +194,8 @@ export class S3Adapter {
       region: config.region,
       endpoint: config.endpoint,
       forcePathStyle: config.forcePathStyle ?? true,
+      requestChecksumCalculation: 'WHEN_REQUIRED',
+      responseChecksumValidation: 'WHEN_REQUIRED',
       credentials: {
         accessKeyId: config.accessKeyId,
         secretAccessKey: config.secretAccessKey,

lib/tabInteractions.test.ts

@@ -0,0 +1,66 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import type React from "react";
+
+import {
+  MIDDLE_MOUSE_BUTTON,
+  handleTabMiddleClickClose,
+  handleTabMiddleMouseDown,
+} from "./tabInteractions.ts";
+
+interface FakeMouseEvent {
+  button: number;
+  preventDefault: () => void;
+  stopPropagation: () => void;
+}
+
+const makeEvent = (button: number) => {
+  const calls = { preventDefault: 0, stopPropagation: 0 };
+  const event = {
+    button,
+    preventDefault: () => {
+      calls.preventDefault++;
+    },
+    stopPropagation: () => {
+      calls.stopPropagation++;
+    },
+  } satisfies FakeMouseEvent;
+  return { event: event as unknown as React.MouseEvent, calls };
+};
+
+test("handleTabMiddleClickClose closes the tab on a middle click", () => {
+  let closed = 0;
+  const { event, calls } = makeEvent(MIDDLE_MOUSE_BUTTON);
+
+  handleTabMiddleClickClose(event, () => {
+    closed++;
+  });
+
+  assert.equal(closed, 1);
+  assert.equal(calls.preventDefault, 1);
+  assert.equal(calls.stopPropagation, 1);
+});
+
+test("handleTabMiddleClickClose ignores left and right clicks", () => {
+  for (const button of [0, 2]) {
+    let closed = 0;
+    const { event, calls } = makeEvent(button);
+
+    handleTabMiddleClickClose(event, () => {
+      closed++;
+    });
+
+    assert.equal(closed, 0, `button ${button} must not close the tab`);
+    assert.equal(calls.preventDefault, 0);
+  }
+});
+
+test("handleTabMiddleMouseDown suppresses autoscroll only for the middle button", () => {
+  const middle = makeEvent(MIDDLE_MOUSE_BUTTON);
+  handleTabMiddleMouseDown(middle.event);
+  assert.equal(middle.calls.preventDefault, 1);
+
+  const left = makeEvent(0);
+  handleTabMiddleMouseDown(left.event);
+  assert.equal(left.calls.preventDefault, 0);
+});

lib/tabInteractions.ts

@@ -0,0 +1,34 @@
+import type React from "react";
+
+/**
+ * The DOM `MouseEvent.button` value for the middle mouse button (wheel click).
+ * 0 = left/primary, 1 = middle, 2 = right/secondary.
+ */
+export const MIDDLE_MOUSE_BUTTON = 1;
+
+/**
+ * Suppress the Chromium/Electron middle-click autoscroll affordance on a tab.
+ * Wire to `onMouseDown`: autoscroll is armed on mousedown, so preventing the
+ * default there stops the panning-cursor overlay from appearing when a user
+ * middle-clicks a tab to close it (#1044).
+ */
+export const handleTabMiddleMouseDown = (e: React.MouseEvent): void => {
+  if (e.button === MIDDLE_MOUSE_BUTTON) {
+    e.preventDefault();
+  }
+};
+
+/**
+ * Close a tab when it is middle-clicked. Wire to `onAuxClick`, which fires for
+ * a completed non-primary click. Left clicks (tab activation) and right clicks
+ * (context menu) are ignored so existing behavior is untouched.
+ */
+export const handleTabMiddleClickClose = (
+  e: React.MouseEvent,
+  close: () => void,
+): void => {
+  if (e.button !== MIDDLE_MOUSE_BUTTON) return;
+  e.preventDefault();
+  e.stopPropagation();
+  close();
+};

package.json

@@ -28,7 +28,7 @@
     "pack:linux": "npm run build && cross-env NODE_OPTIONS=--disable-warning=DEP0190 electron-builder --config electron-builder.config.cjs --linux --publish=never",
     "pack:linux-x64": "npm run build && cross-env npm_config_arch=x64 NODE_OPTIONS=--disable-warning=DEP0190 electron-builder --config electron-builder.config.cjs --linux --x64 --publish=never",
     "pack:linux-arm64": "npm run build && cross-env npm_config_arch=arm64 NODE_OPTIONS=--disable-warning=DEP0190 electron-builder --config electron-builder.config.cjs --linux --arm64 --publish=never",
-    "postinstall": "electron-builder install-app-deps && patch-package",
+    "postinstall": "electron-builder install-app-deps && patch-package && node scripts/patch-xterm-webgl-atlas.cjs",
     "rebuild": "electron-builder install-app-deps",
     "tool:cli": "node electron/cli/netcatty-tool-cli.cjs",
     "lint": "eslint .",

patches/ssh2+1.17.0.patch

@@ -738,3 +738,40 @@ index 9f33c02..9751164 100644
        }
        if (names !== undefined) {
          sftp._debug && sftp._debug(
+diff --git a/node_modules/ssh2/lib/protocol/constants.js b/node_modules/ssh2/lib/protocol/constants.js
+index ad77592..4b3f71a 100644
+--- a/node_modules/ssh2/lib/protocol/constants.js
++++ b/node_modules/ssh2/lib/protocol/constants.js
+@@ -160,4 +160,5 @@ const COMPAT = {
+   DYN_RPORT_BUG: 1 << 2,
+   BUG_DHGEX_LARGE: 1 << 3,
+   IMPLY_RSA_SHA2_SIGALGS: 1 << 4,
++  COMWARE_DHGEX_1024: 1 << 5,
+ };
+@@ -330,6 +331,7 @@ module.exports = {
+   COMPAT_CHECKS: [
+     [ 'Cisco-1.25', COMPAT.BAD_DHGEX ],
+     [ /^Cisco-1[.]/, COMPAT.BUG_DHGEX_LARGE ],
++    [ /^Comware-/, COMPAT.COMWARE_DHGEX_1024 ],
+     [ /^[0-9.]+$/, COMPAT.OLD_EXIT ], // old SSH.com implementations
+     [ /^OpenSSH_5[.][0-9]+/, COMPAT.DYN_RPORT_BUG ],
+     [ /^OpenSSH_7[.]4/, COMPAT.IMPLY_RSA_SHA2_SIGALGS ],
+diff --git a/node_modules/ssh2/lib/protocol/kex.js b/node_modules/ssh2/lib/protocol/kex.js
+index 811e631..4b5f792 100644
+--- a/node_modules/ssh2/lib/protocol/kex.js
++++ b/node_modules/ssh2/lib/protocol/kex.js
+@@ -1377,8 +1377,13 @@ const createKeyExchange = (() => {
+       this._generator = null;
+       this._minBits = GEX_MIN_BITS;
+       this._prefBits = dhEstimate(this.negotiated);
+-      if (this._protocol._compatFlags & COMPAT.BUG_DHGEX_LARGE)
++      if (hashName === 'sha1'
++          && (this._protocol._compatFlags & COMPAT.COMWARE_DHGEX_1024)) {
++        this._minBits = 1024;
++        this._prefBits = 1024;
++      } else if (this._protocol._compatFlags & COMPAT.BUG_DHGEX_LARGE) {
+         this._prefBits = Math.min(this._prefBits, 4096);
++      }
+       this._maxBits = GEX_MAX_BITS;
+     }
+     start() {

scripts/patch-xterm-webgl-atlas.cjs

@@ -0,0 +1,74 @@
+#!/usr/bin/env node
+/**
+ * Disable @xterm/addon-webgl's cross-terminal texture-atlas sharing.
+ *
+ * xterm's WebGL addon shares ONE TextureAtlas across terminal instances whose
+ * config (font / size / theme / device-pixel-ratio) is equal — see
+ * `acquireTextureAtlas`, which does `if (configEquals) { ownedBy.push; return
+ * atlas }`. In a split workspace two panes then share an atlas, so clearing or
+ * rebuilding it for one pane (which netcatty does on resize / DPR change / font
+ * change / tab show to recover from glyph corruption) corrupts the OTHER pane's
+ * rendering — the persistent "花屏 / garbled" report in issue #1063, most
+ * visible in split view where both panes stay on screen.
+ *
+ * Fix: give every terminal its own atlas by removing the "reuse a matching
+ * atlas" loop, so each terminal falls through to creating its own. The published
+ * package is minified, so we string-replace the exact loop in both the CJS and
+ * ESM builds. This runs from `postinstall` (after patch-package).
+ *
+ * Idempotent. If the upstream code changes (e.g. an @xterm/addon-webgl upgrade)
+ * the loop won't be found; we warn loudly but do not fail the install, and the
+ * strings below must then be refreshed for the new version.
+ */
+"use strict";
+const fs = require("node:fs");
+const path = require("node:path");
+
+const MARKER = "/*netcatty:#1063 atlas-isolation*/";
+
+// Exact (minified) "reuse a shared atlas" loop, per @xterm/addon-webgl@0.19.0.
+const TARGETS = [
+  {
+    file: "node_modules/@xterm/addon-webgl/lib/addon-webgl.mjs",
+    loop: "for(let h=0;h<le.length;h++){let f=le[h];if(Mi(f.config,u))return f.ownedBy.push(i),f.atlas}",
+  },
+  {
+    file: "node_modules/@xterm/addon-webgl/lib/addon-webgl.js",
+    loop: "for(let t=0;t<r.length;t++){const i=r[t];if((0,n.configEquals)(i.config,d))return i.ownedBy.push(e),i.atlas}",
+  },
+];
+
+let patched = 0;
+let already = 0;
+let missing = 0;
+
+for (const { file, loop } of TARGETS) {
+  const abs = path.resolve(process.cwd(), file);
+  let src;
+  try {
+    src = fs.readFileSync(abs, "utf8");
+  } catch {
+    console.warn(`[patch-xterm-webgl-atlas] skip (not found): ${file}`);
+    missing++;
+    continue;
+  }
+  if (src.includes(MARKER)) {
+    already++;
+    continue;
+  }
+  if (!src.includes(loop)) {
+    console.warn(
+      `[patch-xterm-webgl-atlas] WARNING: atlas-sharing loop not found in ${file}. ` +
+        "@xterm/addon-webgl likely changed — split-view WebGL may garble again (#1063). " +
+        "Refresh the minified target strings in scripts/patch-xterm-webgl-atlas.cjs.",
+    );
+    missing++;
+    continue;
+  }
+  fs.writeFileSync(abs, src.replace(loop, MARKER));
+  patched++;
+}
+
+console.log(
+  `[patch-xterm-webgl-atlas] atlas isolation: patched=${patched} already=${already} missing=${missing}`,
+);

vite.config.ts

@@ -44,7 +44,6 @@ export default defineConfig(() => {
           output: {
             manualChunks: {
               // Vendor chunks - rarely change, can be cached aggressively
-              'vendor-react': ['react', 'react-dom'],
               'vendor-radix': [
                 '@radix-ui/react-collapsible',
                 '@radix-ui/react-context-menu',