Let single Tab fall through to shell when only ghost text is shown (#745)

Closes #741. Bash/zsh use Tab for native completion, but our ghost-text
accept on single Tab was swallowing the keystroke before it reached the
PTY. Ghost text is still accepted with →; Tab in popup-menu mode is
unchanged (popup is an explicit UI so intent is clear).

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

App.tsx

@@ -18,6 +18,7 @@ import { resolveGroupDefaults, applyGroupDefaults } from './domain/groupConfig';
 import { resolveHostAuth } from './domain/sshAuth';
 import { resolveHostTerminalThemeId } from './domain/terminalAppearance';
 import { collectSessionIds } from './domain/workspace';
+import { resolveCloseIntent } from './application/state/resolveCloseIntent';
 import { TERMINAL_THEMES } from './infrastructure/config/terminalThemes';
 import { useCustomThemes } from './application/state/customThemeStore';
 import type { SyncPayload } from './domain/sync';
@@ -992,6 +993,10 @@ function App({ settings }: { settings: SettingsState }) {
   const addConnectionLogRef = useRef(addConnectionLog);
   addConnectionLogRef.current = addConnectionLog;
 
+  const closeSidePanelRef = useRef<(() => void) | null>(null);
+  const activeSidePanelTabRef = useRef<string | null>(null);
+  const closeTabInFlightRef = useRef(false);
+
   const createLocalTerminalWithCurrentShell = useCallback(() => {
     const resolved = resolveShellSetting(terminalSettings.localShell, discoveredShells);
     const matchedShell = discoveredShells.find(s => s.id === terminalSettings.localShell);
@@ -1025,6 +1030,44 @@ function App({ settings }: { settings: SettingsState }) {
     return hotkeyScheme === 'mac' ? closeTabBinding.mac : closeTabBinding.pc;
   }, [hotkeyScheme, keyBindings]);
 
+  const confirmIfBusyLocalTerminal = useCallback(
+    async (sessionIds: string[]): Promise<boolean> => {
+      const bridge = netcattyBridge.get();
+      const localIds = sessionIds.filter((id) => {
+        const s = sessions.find((x) => x.id === id);
+        return s?.protocol === 'local';
+      });
+      const busyCommands: string[] = [];
+      for (const id of localIds) {
+        const children = (await bridge?.ptyGetChildProcesses?.(id)) ?? [];
+        if (children.length > 0) {
+          busyCommands.push(children[0].command);
+        }
+      }
+      if (busyCommands.length === 0) return true;
+
+      const primary = busyCommands[0];
+      const extraCount = busyCommands.length - 1;
+      const message =
+        extraCount > 0
+          ? t('confirm.closeBusyTerminal.messageWithMore', {
+              command: primary,
+              count: extraCount,
+            })
+          : t('confirm.closeBusyTerminal.message', { command: primary });
+
+      const ok = await bridge?.confirmCloseBusy?.({
+        command: primary,
+        title: t('confirm.closeBusyTerminal.title'),
+        message,
+        cancelLabel: t('confirm.closeBusyTerminal.cancel'),
+        closeLabel: t('confirm.closeBusyTerminal.close'),
+      });
+      return ok === true;
+    },
+    [sessions, t],
+  );
+
   // Shared hotkey action handler - used by both global handler and terminal callback
   const executeHotkeyAction = useCallback((action: string, e: KeyboardEvent) => {
     // Build complete tab list: vault + (sftp when visible) + sessions/workspaces.
@@ -1069,18 +1112,52 @@ function App({ settings }: { settings: SettingsState }) {
       }
       case 'closeTab': {
         const currentId = activeTabStore.getActiveTabId();
-        if (currentId !== 'vault' && currentId !== 'sftp') {
-          // Find if it's a session or workspace
-          const session = sessions.find(s => s.id === currentId);
-          if (session) {
-            closeSession(currentId);
-          } else {
-            const workspace = workspaces.find(w => w.id === currentId);
-            if (workspace) {
-              closeWorkspace(currentId);
+        if (!currentId || currentId === 'vault' || currentId === 'sftp') break;
+        if (closeTabInFlightRef.current) break;
+
+        const session = sessions.find((s) => s.id === currentId) ?? null;
+        const workspace = workspaces.find((w) => w.id === currentId) ?? null;
+
+        const focusIsInsideTerminal = !!document.activeElement?.closest('[data-session-id]');
+        const activeSidePanel = activeSidePanelTabRef.current;
+
+        const intent = resolveCloseIntent({
+          activeTabId: currentId,
+          workspace: workspace ? { id: workspace.id, focusedSessionId: workspace.focusedSessionId } : null,
+          sessionForTab: session,
+          activeSidePanelTab: activeSidePanel,
+          focusIsInsideTerminal,
+        });
+
+        closeTabInFlightRef.current = true;
+        (async () => {
+          try {
+            switch (intent.kind) {
+              case 'closeTerminal':
+              case 'closeSingleTab': {
+                const ok = await confirmIfBusyLocalTerminal([intent.sessionId]);
+                if (ok) closeSession(intent.sessionId);
+                return;
+              }
+              case 'closeSidePanel': {
+                closeSidePanelRef.current?.();
+                return;
+              }
+              case 'closeWorkspace': {
+                const ids = sessions.filter((s) => s.workspaceId === intent.workspaceId).map((s) => s.id);
+                const ok = await confirmIfBusyLocalTerminal(ids);
+                if (ok) closeWorkspace(intent.workspaceId);
+                return;
+              }
+              case 'noop':
+              default:
+                return;
             }
+          } finally {
+            closeTabInFlightRef.current = false;
           }
-        }
+        })();
+
         break;
       }
       case 'newTab':
@@ -1193,7 +1270,7 @@ function App({ settings }: { settings: SettingsState }) {
         break;
       }
     }
-  }, [orderedTabs, sessions, workspaces, setActiveTabId, closeSession, closeWorkspace, createLocalTerminalWithCurrentShell, splitSessionWithCurrentShell, moveFocusInWorkspace, toggleBroadcast, settings.showSftpTab]);
+  }, [orderedTabs, sessions, workspaces, setActiveTabId, closeSession, closeWorkspace, createLocalTerminalWithCurrentShell, splitSessionWithCurrentShell, moveFocusInWorkspace, toggleBroadcast, settings.showSftpTab, confirmIfBusyLocalTerminal]);
 
   // Callback for terminal to invoke app-level hotkey actions
   const handleHotkeyAction = useCallback((action: string, e: KeyboardEvent) => {
@@ -1684,6 +1761,8 @@ function App({ settings }: { settings: SettingsState }) {
           sessionLogsEnabled={sessionLogsEnabled}
           sessionLogsDir={sessionLogsDir}
           sessionLogsFormat={sessionLogsFormat}
+          closeSidePanelRef={closeSidePanelRef}
+          activeSidePanelTabRef={activeSidePanelTabRef}
         />
 
         {/* Log Views - readonly terminal replays */}

application/i18n/locales/en.ts

@@ -56,6 +56,11 @@ const en: Messages = {
   'confirm.deleteHost': 'Delete Host "{name}"?',
   'confirm.deleteIdentity': 'Delete Identity "{name}"?',
   'confirm.removeProvider': 'Remove provider "{name}"?',
+  'confirm.closeBusyTerminal.title': 'Confirm close',
+  'confirm.closeBusyTerminal.message': 'Process "{command}" is still running and will be terminated.',
+  'confirm.closeBusyTerminal.messageWithMore': 'Process "{command}" and {count} other running process(es) will be terminated.',
+  'confirm.closeBusyTerminal.cancel': 'Cancel',
+  'confirm.closeBusyTerminal.close': 'Close',
   'dialog.createWorkspace.title': 'Create Workspace',
   'dialog.renameWorkspace.title': 'Rename workspace',
   'dialog.renameSession.title': 'Rename session',
@@ -467,6 +472,30 @@ const en: Messages = {
   'sync.autoSync.emptyVaultConflict.keepEmpty': 'Keep Empty',
   'sync.autoSync.emptyVaultConflict.keepEmptyDesc': 'Start fresh with an empty vault',
   'sync.autoSync.emptyVaultConflict.cloudSummary': '{hosts} hosts, {keys} keys, {snippets} snippets',
+  'sync.autoSync.emptyVaultManual': 'Cannot sync: the local vault is empty. Restore from a local backup or enable Force Push in the sync panel first.',
+
+  'sync.blocked.title': 'Sync paused',
+  'sync.blocked.reason.bulkShrink': 'Would delete {lost} of {baseCount} {entityType} from cloud ({percent}% reduction).',
+  'sync.blocked.reason.largeShrink': 'Would delete {lost} {entityType} from cloud.',
+  'sync.blocked.detail': 'This is usually caused by a degraded local state (keychain failure, partial data load). Restore from a local backup, or force-push if you truly meant to remove these entries.',
+  'sync.blocked.restoreButton': 'Restore from local backup',
+  'sync.blocked.forcePushButton': 'Force push anyway',
+
+  'sync.forcePush.title': 'Confirm force push',
+  'sync.forcePush.body': 'You are about to remove {lost} {entityType} from the cloud. This cannot be undone. Proceed?',
+  'sync.forcePush.confirm': 'Yes, push anyway',
+  'sync.forcePush.cancel': 'Cancel',
+
+  'sync.entityType.hosts': 'hosts',
+  'sync.entityType.keys': 'keys',
+  'sync.entityType.identities': 'identities',
+  'sync.entityType.snippets': 'snippets',
+  'sync.entityType.customGroups': 'groups',
+  'sync.entityType.snippetPackages': 'snippet packages',
+  'sync.entityType.knownHosts': 'known-host entries',
+  'sync.entityType.portForwardingRules': 'port-forwarding rules',
+  'sync.entityType.groupConfigs': 'group configs',
+
   'sync.credentialsUnavailable': 'This device cannot decrypt some saved credentials. Re-enter credentials locally before syncing.',
   'time.never': 'Never',
   'time.justNow': 'Just now',

application/i18n/locales/zh-CN.ts

@@ -43,6 +43,11 @@ const zhCN: Messages = {
   'confirm.deleteHost': '删除主机 "{name}"？',
   'confirm.deleteIdentity': '删除身份 "{name}"？',
   'confirm.removeProvider': '移除提供商 "{name}"？',
+  'confirm.closeBusyTerminal.title': '确认关闭',
+  'confirm.closeBusyTerminal.message': '进程 "{command}" 仍在运行，关闭后会被终止。',
+  'confirm.closeBusyTerminal.messageWithMore': '进程 "{command}" 及其他 {count} 个正在运行的进程将被终止。',
+  'confirm.closeBusyTerminal.cancel': '取消',
+  'confirm.closeBusyTerminal.close': '关闭',
   'dialog.renameWorkspace.title': '重命名工作区',
   'dialog.renameSession.title': '重命名会话',
   'field.name': '名称',
@@ -286,6 +291,30 @@ const zhCN: Messages = {
   'sync.autoSync.emptyVaultConflict.keepEmpty': '保持为空',
   'sync.autoSync.emptyVaultConflict.keepEmptyDesc': '从头开始，使用空的主机库',
   'sync.autoSync.emptyVaultConflict.cloudSummary': '{hosts} 台主机，{keys} 个密钥，{snippets} 个代码片段',
+  'sync.autoSync.emptyVaultManual': '无法同步：本地 vault 为空。请先从本地备份恢复，或在同步面板里使用"强制推送"。',
+
+  'sync.blocked.title': '同步已暂停',
+  'sync.blocked.reason.bulkShrink': '即将从云端删除 {baseCount} 条 {entityType} 中的 {lost} 条（缩减 {percent}%）。',
+  'sync.blocked.reason.largeShrink': '即将从云端删除 {lost} 条 {entityType}。',
+  'sync.blocked.detail': '通常是本地状态异常（钥匙串故障、数据加载不全）导致。请从本地备份恢复，如果确实要删这些条目请使用强制推送。',
+  'sync.blocked.restoreButton': '从本地备份恢复',
+  'sync.blocked.forcePushButton': '强制推送',
+
+  'sync.forcePush.title': '确认强制推送',
+  'sync.forcePush.body': '你将从云端移除 {lost} 条 {entityType}，此操作不可撤销。继续？',
+  'sync.forcePush.confirm': '确认推送',
+  'sync.forcePush.cancel': '取消',
+
+  'sync.entityType.hosts': '主机',
+  'sync.entityType.keys': '密钥',
+  'sync.entityType.identities': '身份',
+  'sync.entityType.snippets': '代码片段',
+  'sync.entityType.customGroups': '分组',
+  'sync.entityType.snippetPackages': '片段包',
+  'sync.entityType.knownHosts': '主机密钥记录',
+  'sync.entityType.portForwardingRules': '端口转发规则',
+  'sync.entityType.groupConfigs': '分组配置',
+
   'sync.credentialsUnavailable': '当前设备无法解密部分已保存凭据。请先在本地重新输入凭据后再同步。',
   'time.never': '从未',
   'time.justNow': '刚刚',

application/localVaultBackups.ts

@@ -6,15 +6,38 @@ import {
   STORAGE_KEY_VAULT_RESTORE_IN_PROGRESS_UNTIL,
 } from '../infrastructure/config/storageKeys';
 import { localStorageAdapter } from '../infrastructure/persistence/localStorageAdapter';
+import { getCloudSyncManager } from '../infrastructure/services/CloudSyncManager';
 import { netcattyBridge } from '../infrastructure/services/netcattyBridge';
 import { hasMeaningfulSyncData } from './syncPayload';
 
+/**
+ * Snapshot the current sync data version (the integer that increments
+ * on each successful cloud sync). Returns undefined when the value is
+ * 0 (never synced) or unavailable, so the UI can fall back to timestamp.
+ */
+function captureCurrentSyncDataVersion(): number | undefined {
+  try {
+    const state = getCloudSyncManager().getState();
+    const v = state.localVersion;
+    return typeof v === 'number' && v > 0 ? v : undefined;
+  } catch {
+    return undefined;
+  }
+}
+
 export type LocalVaultBackupReason = 'app_version_change' | 'before_restore';
 
 export interface LocalVaultBackupPreview {
   id: string;
   createdAt: number;
   reason: LocalVaultBackupReason;
+  /** Sync-data version at the time the snapshot was taken (the integer
+   * that the CloudSyncManager increments on each successful cloud sync).
+   * Undefined when the user had never synced yet, or for legacy backups
+   * persisted before this field was added. */
+  syncDataVersion?: number;
+  /** App version transition fields, only for `app_version_change` records.
+   * Kept for backward compatibility with already-persisted backups. */
   sourceAppVersion?: string;
   targetAppVersion?: string;
   fingerprint: string;
@@ -94,6 +117,7 @@ export async function createLocalVaultBackup(
   payload: SyncPayload,
   options: {
     reason: LocalVaultBackupReason;
+    syncDataVersion?: number;
     sourceAppVersion?: string;
     targetAppVersion?: string;
     maxCount?: number;
@@ -118,6 +142,10 @@ export async function createLocalVaultBackup(
     const result = await bridge.createVaultBackup({
       payload,
       reason: options.reason,
+      // Default to the live cloud-sync version so every new backup carries
+      // it even when the caller didn't pass one explicitly. Bridge sanitizer
+      // drops invalid values (non-positive / non-finite), so this is safe.
+      syncDataVersion: options.syncDataVersion ?? captureCurrentSyncDataVersion(),
       sourceAppVersion: options.sourceAppVersion,
       targetAppVersion: options.targetAppVersion,
       maxCount: options.maxCount ?? getLocalVaultBackupMaxCount(),

application/state/resolveCloseIntent.test.ts

@@ -0,0 +1,110 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { resolveCloseIntent } from "./resolveCloseIntent.ts";
+
+const baseWorkspace = {
+  id: "w1",
+  focusedSessionId: "s1",
+};
+
+const baseSession = { id: "s1" };
+
+test("non-workspace tab → closeSingleTab with session id", () => {
+  const result = resolveCloseIntent({
+    activeTabId: "s1",
+    workspace: null,
+    sessionForTab: baseSession,
+    activeSidePanelTab: null,
+    focusIsInsideTerminal: true,
+  });
+  assert.deepEqual(result, { kind: "closeSingleTab", sessionId: "s1" });
+});
+
+test("non-workspace session tab + sidebar open → closeSidePanel (sidebar beats session close)", () => {
+  const r = resolveCloseIntent({
+    activeTabId: "s1",
+    workspace: null,
+    sessionForTab: { id: "s1" },
+    activeSidePanelTab: "ai",
+    focusIsInsideTerminal: true, // focus IS in terminal, but sidebar wins
+  });
+  assert.deepEqual(r, { kind: "closeSidePanel" });
+});
+
+test("vault/sftp tab → noop", () => {
+  const r = resolveCloseIntent({
+    activeTabId: "vault",
+    workspace: null,
+    sessionForTab: null,
+    activeSidePanelTab: null,
+    focusIsInsideTerminal: false,
+  });
+  assert.deepEqual(r, { kind: "noop" });
+});
+
+test("workspace + focus in terminal + sidebar open → closeSidePanel wins (sidebar beats focus)", () => {
+  const r = resolveCloseIntent({
+    activeTabId: "w1",
+    workspace: baseWorkspace,
+    sessionForTab: null,
+    activeSidePanelTab: "ai",
+    focusIsInsideTerminal: true,
+  });
+  assert.deepEqual(r, { kind: "closeSidePanel" });
+});
+
+test("workspace + focus NOT in terminal + sidebar open → closeSidePanel", () => {
+  const r = resolveCloseIntent({
+    activeTabId: "w1",
+    workspace: baseWorkspace,
+    sessionForTab: null,
+    activeSidePanelTab: "sftp",
+    focusIsInsideTerminal: false,
+  });
+  assert.deepEqual(r, { kind: "closeSidePanel" });
+});
+
+test("workspace + sidebar closed + focus in terminal → closeTerminal", () => {
+  const r = resolveCloseIntent({
+    activeTabId: "w1",
+    workspace: baseWorkspace,
+    sessionForTab: null,
+    activeSidePanelTab: null,
+    focusIsInsideTerminal: true,
+  });
+  assert.deepEqual(r, { kind: "closeTerminal", sessionId: "s1" });
+});
+
+test("workspace + sidebar closed + focus NOT in terminal → closeWorkspace", () => {
+  const r = resolveCloseIntent({
+    activeTabId: "w1",
+    workspace: baseWorkspace,
+    sessionForTab: null,
+    activeSidePanelTab: null,
+    focusIsInsideTerminal: false,
+  });
+  assert.deepEqual(r, { kind: "closeWorkspace", workspaceId: "w1" });
+});
+
+test("workspace with no focused session + sidebar closed → closeWorkspace", () => {
+  const r = resolveCloseIntent({
+    activeTabId: "w1",
+    workspace: { id: "w1", focusedSessionId: undefined },
+    sessionForTab: null,
+    activeSidePanelTab: null,
+    focusIsInsideTerminal: true, // even if flag true, no focused id → cannot closeTerminal
+  });
+  assert.deepEqual(r, { kind: "closeWorkspace", workspaceId: "w1" });
+});
+
+test("workspace with no focused session + sidebar open → closeSidePanel", () => {
+  const r = resolveCloseIntent({
+    activeTabId: "w1",
+    workspace: { id: "w1", focusedSessionId: undefined },
+    sessionForTab: null,
+    activeSidePanelTab: "ai",
+    focusIsInsideTerminal: false,
+  });
+  assert.deepEqual(r, { kind: "closeSidePanel" });
+});

application/state/resolveCloseIntent.ts

@@ -0,0 +1,43 @@
+export type CloseIntent =
+  | { kind: 'closeTerminal'; sessionId: string }
+  | { kind: 'closeSidePanel' }
+  | { kind: 'closeWorkspace'; workspaceId: string }
+  | { kind: 'closeSingleTab'; sessionId: string }
+  | { kind: 'noop' };
+
+export interface ResolveCloseInput {
+  activeTabId: string | null;
+  workspace: { id: string; focusedSessionId?: string } | null;
+  sessionForTab: { id: string } | null;
+  activeSidePanelTab: string | null;
+  focusIsInsideTerminal: boolean;
+}
+
+export function resolveCloseIntent(input: ResolveCloseInput): CloseIntent {
+  const { activeTabId, workspace, sessionForTab, activeSidePanelTab, focusIsInsideTerminal } = input;
+
+  if (!activeTabId) return { kind: 'noop' };
+
+  // Sidebar always wins — applies to any tab type (workspace, single-session, etc.).
+  // Modals take priority over this but are intercepted upstream in App.tsx before the
+  // hotkey reaches resolveCloseIntent.
+  if (activeSidePanelTab !== null) {
+    return { kind: 'closeSidePanel' };
+  }
+
+  if (sessionForTab && !workspace) {
+    return { kind: 'closeSingleTab', sessionId: sessionForTab.id };
+  }
+
+  if (!workspace) {
+    // e.g. 'vault', 'sftp', or any non-closable pinned tab
+    return { kind: 'noop' };
+  }
+
+  const focusedSessionId = workspace.focusedSessionId;
+  if (focusedSessionId && focusIsInsideTerminal) {
+    return { kind: 'closeTerminal', sessionId: focusedSessionId };
+  }
+
+  return { kind: 'closeWorkspace', workspaceId: workspace.id };
+}

application/state/useAutoSync.ts

@@ -247,19 +247,23 @@ export const useAutoSync = (config: AutoSyncConfig) => {
         throw new Error(t('sync.credentialsUnavailable'));
       }
 
-      // Prevent pushing an empty vault to cloud. This is almost always
+      // Refuse to push an empty vault to cloud. This is almost always
       // a sign that the local state was lost (update, import failure,
       // storage corruption) rather than a deliberate "delete everything".
-      // We only block auto-sync — manual trigger from Settings can still
-      // push if the user explicitly wants to.
+      // Both auto and manual triggers are blocked; the user can still
+      // use Force Push from the SyncBlocked banner if they genuinely
+      // want to wipe the cloud.
       //
       // This pairs with the inspect-failure "fail open" behavior in
       // checkRemoteVersion below: if inspect transiently errors we still
       // let auto-sync run, trusting this guard to refuse if local is
       // truly empty rather than letting an empty state clobber remote.
-      if (!hasMeaningfulSyncData(payload) && trigger === 'auto') {
-        console.warn('[AutoSync] Blocked: refusing to auto-sync an empty vault to cloud');
-        return;
+      if (!hasMeaningfulSyncData(payload)) {
+        if (trigger === 'auto') {
+          console.warn('[AutoSync] Blocked: refusing to auto-sync an empty vault to cloud');
+          return;
+        }
+        throw new Error(t('sync.autoSync.emptyVaultManual'));
       }
 
       const results = await sync.syncNow(payload);
@@ -479,7 +483,20 @@ export const useAutoSync = (config: AutoSyncConfig) => {
       // that only approximated the correct ordering.
       if (mergeResult.payload) {
         try {
-          await manager.syncAllProviders(mergeResult.payload);
+          const roundTripResults = await manager.syncAllProviders(mergeResult.payload);
+          const wasShrinkBlocked = Array.from(roundTripResults.values()).some(
+            (r) => r.shrinkBlocked === true,
+          );
+          if (wasShrinkBlocked) {
+            // The merged payload is already applied locally and is the source of truth
+            // for THIS device. The blocking only prevents pushing it to cloud, which
+            // is acceptable here — the next user-edit-triggered sync will re-check
+            // (and the user can also force-push from the Settings banner if they
+            // navigate there). Reset syncState so we don't leave the manager wedged
+            // in BLOCKED with no banner visible.
+            console.warn('[AutoSync] Post-merge round-trip was shrink-blocked; merged data applied locally, reset syncState to IDLE for next attempt.');
+            manager.clearShrinkBlockedState();
+          }
           // Suppress the debounced follow-up tick that otherwise fires
           // once React commits the applied state, since we've just
           // already pushed that exact payload upstream.

application/state/useCloudSync.ts

@@ -26,7 +26,9 @@ import {
 import {
   getCloudSyncManager,
   type SyncManagerState,
+  type SyncEventCallback,
 } from '../../infrastructure/services/CloudSyncManager';
+import type { ShrinkFinding } from '../../domain/syncGuards';
 import { netcattyBridge } from '../../infrastructure/services/netcattyBridge';
 import type { DeviceFlowState } from '../../infrastructure/services/adapters/GitHubAdapter';
 
@@ -55,7 +57,7 @@ export interface CloudSyncHook {
   // Computed
   hasAnyConnectedProvider: boolean;
   connectedProviderCount: number;
-  overallSyncStatus: 'none' | 'synced' | 'syncing' | 'error' | 'conflict';
+  overallSyncStatus: 'none' | 'synced' | 'syncing' | 'error' | 'conflict' | 'blocked';
   
   // Master Key Actions
   setupMasterKey: (password: string, confirmPassword: string) => Promise<void>;
@@ -86,8 +88,8 @@ export interface CloudSyncHook {
   resetProviderStatus: (provider: CloudProvider) => void;
 
   // Sync Actions
-  syncNow: (payload: SyncPayload) => Promise<Map<CloudProvider, SyncResult>>;
-  syncToProvider: (provider: CloudProvider, payload: SyncPayload) => Promise<SyncResult>;
+  syncNow: (payload: SyncPayload, opts?: { overrideShrink?: boolean }) => Promise<Map<CloudProvider, SyncResult>>;
+  syncToProvider: (provider: CloudProvider, payload: SyncPayload, opts?: { overrideShrink?: boolean }) => Promise<SyncResult>;
   downloadFromProvider: (provider: CloudProvider) => Promise<SyncPayload | null>;
   resolveConflict: (resolution: ConflictResolution) => Promise<SyncPayload | null>;
 
@@ -116,6 +118,12 @@ export interface CloudSyncHook {
   formatLastSync: (timestamp?: number) => string;
   getProviderDotColor: (provider: CloudProvider) => string;
   refresh: () => void;
+
+  // Event subscription (for non-state events like SYNC_BLOCKED_SHRINK)
+  subscribeToEvents: (callback: SyncEventCallback) => () => void;
+
+  // Shrink-block state query (for banner hydration on mount)
+  getShrinkBlockedFinding: () => Extract<ShrinkFinding, { suspicious: true }> | null;
 }
 
 // ============================================================================
@@ -190,7 +198,8 @@ export const useCloudSync = (): CloudSyncHook => {
     ).length;
   }, [state.providers]);
   
-  const overallSyncStatus = useMemo((): 'none' | 'synced' | 'syncing' | 'error' | 'conflict' => {
+  const overallSyncStatus = useMemo((): 'none' | 'synced' | 'syncing' | 'error' | 'conflict' | 'blocked' => {
+    if (state.syncState === 'BLOCKED') return 'blocked';
     if (state.syncState === 'CONFLICT') return 'conflict';
     if (state.syncState === 'ERROR') return 'error';
     if (state.syncState === 'SYNCING') return 'syncing';
@@ -422,14 +431,14 @@ export const useCloudSync = (): CloudSyncHook => {
     throw new Error('Vault is locked');
   }, []);
 
-  const syncNowWithUnlock = useCallback(async (payload: SyncPayload) => {
+  const syncNowWithUnlock = useCallback(async (payload: SyncPayload, opts?: { overrideShrink?: boolean }) => {
     await ensureUnlocked();
-    return await manager.syncAllProviders(payload);
+    return await manager.syncAllProviders(payload, opts);
   }, [ensureUnlocked]);
 
-  const syncToProviderWithUnlock = useCallback(async (provider: CloudProvider, payload: SyncPayload) => {
+  const syncToProviderWithUnlock = useCallback(async (provider: CloudProvider, payload: SyncPayload, opts?: { overrideShrink?: boolean }) => {
     await ensureUnlocked();
-    return await manager.syncToProvider(provider, payload);
+    return await manager.syncToProvider(provider, payload, opts);
   }, [ensureUnlocked]);
 
   const downloadFromProviderWithUnlock = useCallback(async (provider: CloudProvider) => {
@@ -437,6 +446,16 @@ export const useCloudSync = (): CloudSyncHook => {
     return await manager.downloadFromProvider(provider);
   }, [ensureUnlocked]);
 
+  const subscribeToEvents = useCallback(
+    (callback: SyncEventCallback) => manager.subscribe(callback),
+    [],
+  );
+
+  const getShrinkBlockedFinding = useCallback(
+    () => manager.getShrinkBlockedFinding(),
+    [],
+  );
+
   const resolveConflictWithUnlock = useCallback(async (resolution: ConflictResolution) => {
     await ensureUnlocked();
     return await manager.resolveConflict(resolution);
@@ -505,6 +524,12 @@ export const useCloudSync = (): CloudSyncHook => {
     formatLastSync,
     getProviderDotColor,
     refresh,
+
+    // Event subscription
+    subscribeToEvents,
+
+    // Shrink-block state query
+    getShrinkBlockedFinding,
   };
 };
 

application/state/useSessionState.ts

@@ -141,19 +141,48 @@ export const useSessionState = () => {
     setSessions(prev => prev.map(s => s.id === sessionId ? { ...s, status } : s));
   }, []);
 
+  const closeWorkspace = useCallback((workspaceId: string) => {
+    setWorkspaces(prevWorkspaces => {
+      const remainingWorkspaces = prevWorkspaces.filter(w => w.id !== workspaceId);
+
+      setSessions(prevSessions => prevSessions.filter(s => s.workspaceId !== workspaceId));
+
+      const currentActiveTabId = activeTabStore.getActiveTabId();
+      if (currentActiveTabId === workspaceId) {
+        if (remainingWorkspaces.length > 0) {
+          setActiveTabId(remainingWorkspaces[remainingWorkspaces.length - 1].id);
+        } else {
+          setActiveTabId('vault');
+        }
+      }
+
+      return remainingWorkspaces;
+    });
+  }, [setActiveTabId]);
+
   const closeSession = useCallback((sessionId: string, e?: MouseEvent) => {
     e?.stopPropagation();
-    
+
+    // Pre-compute outside the setSessions updater so we don't depend on React
+    // having run the updater by the time we queue the microtask. React 18+ does
+    // not guarantee updater execution timing under concurrent scheduling.
+    const sessionBeingClosed = sessions.find(s => s.id === sessionId);
+    const workspaceIdToMaybeClose =
+      sessionBeingClosed?.workspaceId &&
+      sessions.every(s => s.id === sessionId || s.workspaceId !== sessionBeingClosed.workspaceId)
+        ? sessionBeingClosed.workspaceId
+        : undefined;
+
     setSessions(prevSessions => {
       const targetSession = prevSessions.find(s => s.id === sessionId);
       const wsId = targetSession?.workspaceId;
-      
+
       setWorkspaces(prevWorkspaces => {
         let removedWorkspaceId: string | null = null;
         let nextWorkspaces = prevWorkspaces;
         let dissolvedWorkspaceId: string | null = null;
         let lastRemainingSessionId: string | null = null;
-        
+
         if (wsId) {
           nextWorkspaces = prevWorkspaces
             .map(ws => {
@@ -163,7 +192,7 @@ export const useSessionState = () => {
                 removedWorkspaceId = ws.id;
                 return null;
               }
-              
+
               // Check if only 1 session remains - dissolve workspace
               const remainingSessionIds = collectSessionIds(pruned);
               if (remainingSessionIds.length === 1) {
@@ -171,12 +200,12 @@ export const useSessionState = () => {
                 lastRemainingSessionId = remainingSessionIds[0];
                 return null;
               }
-              
+
               return { ...ws, root: pruned };
             })
             .filter((ws): ws is Workspace => Boolean(ws));
         }
-        
+
         const remainingSessions = prevSessions.filter(s => s.id !== sessionId);
         const fallbackWorkspace = nextWorkspaces[nextWorkspaces.length - 1];
         const fallbackSolo = remainingSessions.filter(s => !s.workspaceId).slice(-1)[0];
@@ -198,10 +227,10 @@ export const useSessionState = () => {
         } else if (wsId && currentActiveTabId === wsId && !nextWorkspaces.find(w => w.id === wsId)) {
           setActiveTabId(getFallback());
         }
-        
+
         return nextWorkspaces;
       });
-      
+
       // Check if we need to dissolve a workspace (convert remaining session to orphan)
       if (targetSession?.workspaceId) {
         const ws = workspaces.find(w => w.id === targetSession.workspaceId);
@@ -218,29 +247,14 @@ export const useSessionState = () => {
           }
         }
       }
-	      
-	      return prevSessions.filter(s => s.id !== sessionId);
-	    });
-	  }, [workspaces, setActiveTabId]);
 
-  const closeWorkspace = useCallback((workspaceId: string) => {
-    setWorkspaces(prevWorkspaces => {
-      const remainingWorkspaces = prevWorkspaces.filter(w => w.id !== workspaceId);
-      
-      setSessions(prevSessions => prevSessions.filter(s => s.workspaceId !== workspaceId));
-      
-      const currentActiveTabId = activeTabStore.getActiveTabId();
-      if (currentActiveTabId === workspaceId) {
-        if (remainingWorkspaces.length > 0) {
-          setActiveTabId(remainingWorkspaces[remainingWorkspaces.length - 1].id);
-        } else {
-          setActiveTabId('vault');
-        }
-      }
-      
-	      return remainingWorkspaces;
-	    });
-	  }, [setActiveTabId]);
+      return prevSessions.filter(s => s.id !== sessionId);
+    });
+
+    if (workspaceIdToMaybeClose) {
+      queueMicrotask(() => closeWorkspace(workspaceIdToMaybeClose!));
+    }
+  }, [sessions, workspaces, setActiveTabId, closeWorkspace]);
 
   const startSessionRename = useCallback((sessionId: string) => {
     setSessions(prevSessions => {
@@ -654,16 +668,22 @@ export const useSessionState = () => {
   const copySession = useCallback((sessionId: string, options?: {
     localShellType?: TerminalSession['shellType'];
   }) => {
+    // Pre-allocate the new id outside the updater so StrictMode's
+    // double-invocation of the functional updater doesn't mint two ids.
+    const newSessionId = crypto.randomUUID();
+
     setSessions(prevSessions => {
       const session = prevSessions.find(s => s.id === sessionId);
+      // Source may have been closed between the user's action and this
+      // update running; in that case skip entirely — do NOT switch the
+      // active tab or insert into tabOrder, which would leave dangling ids.
       if (!session) return prevSessions;
       const nextShellType = session.protocol === 'local'
         ? options?.localShellType
         : session.shellType;
 
-      // Create a new session with the same connection info
       const newSession: TerminalSession = {
-        id: crypto.randomUUID(),
+        id: newSessionId,
         hostId: session.hostId,
         hostLabel: session.hostLabel,
         hostname: session.hostname,
@@ -681,10 +701,40 @@ export const useSessionState = () => {
         localShellIcon: session.localShellIcon,
       };
 
-      setActiveTabId(newSession.id);
+      // Schedule the activeTab + tabOrder updates only when creation
+      // actually happens. These nested setStates are idempotent, so
+      // StrictMode's double-invocation is harmless.
+      setActiveTabId(newSessionId);
+      setTabOrder(prevTabOrder => {
+        // Fast path: source is already tracked in tabOrder — splice directly.
+        const directIdx = prevTabOrder.indexOf(sessionId);
+        if (directIdx !== -1) {
+          const next = [...prevTabOrder];
+          next.splice(directIdx + 1, 0, newSessionId);
+          return next;
+        }
+        // Fallback: source is only in the derived tab collections. Rebuild the
+        // effective order (same pattern as reorderTabs) to locate its position.
+        const allTabIds = [
+          ...orphanSessions.map(s => s.id),
+          ...workspaces.map(w => w.id),
+          ...logViews.map(lv => lv.id),
+        ];
+        const allTabIdSet = new Set(allTabIds);
+        const orderedIds = prevTabOrder.filter(id => allTabIdSet.has(id));
+        const orderedIdSet = new Set(orderedIds);
+        const newIds = allTabIds.filter(id => !orderedIdSet.has(id));
+        const currentOrder = [...orderedIds, ...newIds];
+        const sourceIdx = currentOrder.indexOf(sessionId);
+        if (sourceIdx === -1) return [...prevTabOrder, newSessionId];
+        const next = [...currentOrder];
+        next.splice(sourceIdx + 1, 0, newSessionId);
+        return next;
+      });
+
       return [...prevSessions, newSession];
     });
-  }, [setActiveTabId]);
+  }, [orphanSessions, workspaces, logViews, setActiveTabId]);
 
   // Toggle broadcast mode for a workspace
   const toggleBroadcast = useCallback((workspaceId: string) => {

components/CloudSyncSettings.tsx

@@ -7,7 +7,7 @@
  * - Sync status and conflict resolution
  */
 
-import React, { useState, useCallback, useEffect } from 'react';
+import React, { useState, useCallback, useEffect, useRef } from 'react';
 import {
     AlertTriangle,
     Check,
@@ -43,7 +43,9 @@ import { useI18n } from '../application/i18n/I18nProvider';
 import {
     findSyncPayloadEncryptedCredentialPaths,
 } from '../domain/credentials';
-import { isProviderReadyForSync, type CloudProvider, type ConflictInfo, type SyncPayload, type WebDAVAuthType, type WebDAVConfig, type S3Config } from '../domain/sync';
+import { isProviderReadyForSync, type CloudProvider, type ConflictInfo, type SyncPayload, type SyncResult, type WebDAVAuthType, type WebDAVConfig, type S3Config } from '../domain/sync';
+import type { ShrinkFinding } from '../domain/syncGuards';
+import { SyncBlockedBanner } from './sync/SyncBlockedBanner';
 import { cn } from '../lib/utils';
 import { Button } from './ui/button';
 import { Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from './ui/dialog';
@@ -897,20 +899,29 @@ const LocalBackupsPanel: React.FC<LocalBackupsPanelProps> = ({
                                 className="flex items-center gap-3 rounded-lg border border-border/60 p-3"
                             >
                                 <div className="flex-1 min-w-0">
-                                    <div className="flex items-center gap-2 flex-wrap">
-                                        <span className="text-sm font-medium">
-                                            {getReasonLabel(backup.reason)}
-                                        </span>
-                                        <span className="text-xs text-muted-foreground">
-                                            {formatTimestamp(backup.createdAt)}
-                                        </span>
+                                    <div className="text-sm font-medium">
+                                        {backup.syncDataVersion
+                                            ? `v${backup.syncDataVersion}`
+                                            : formatTimestamp(backup.createdAt)}
+                                    </div>
+                                    <div className="text-xs text-muted-foreground mt-1 flex items-center gap-1 flex-wrap">
+                                        <span>{getReasonLabel(backup.reason)}</span>
+                                        {backup.syncDataVersion && (
+                                            <>
+                                                <span aria-hidden="true">·</span>
+                                                <span>{formatTimestamp(backup.createdAt)}</span>
+                                            </>
+                                        )}
                                         {backup.sourceAppVersion && backup.targetAppVersion && (
-                                            <span className="text-xs text-muted-foreground">
-                                                {t('cloudSync.localBackups.versionChange', {
-                                                    from: backup.sourceAppVersion,
-                                                    to: backup.targetAppVersion,
-                                                })}
-                                            </span>
+                                            <>
+                                                <span aria-hidden="true">·</span>
+                                                <span>
+                                                    {t('cloudSync.localBackups.versionChange', {
+                                                        from: backup.sourceAppVersion,
+                                                        to: backup.targetAppVersion,
+                                                    })}
+                                                </span>
+                                            </>
                                         )}
                                     </div>
                                     <div className="text-xs text-muted-foreground mt-1">
@@ -974,13 +985,30 @@ const LocalBackupsPanel: React.FC<LocalBackupsPanelProps> = ({
                     </DialogHeader>
                     {pendingRestoreBackup && (
                         <div className="rounded-lg border border-border/60 bg-muted/30 p-3 text-xs space-y-1">
-                            <div className="flex items-center gap-2 flex-wrap">
-                                <span className="font-medium">
-                                    {getReasonLabel(pendingRestoreBackup.reason)}
-                                </span>
-                                <span className="text-muted-foreground">
-                                    {formatTimestamp(pendingRestoreBackup.createdAt)}
-                                </span>
+                            <div className="font-medium">
+                                {pendingRestoreBackup.syncDataVersion
+                                    ? `v${pendingRestoreBackup.syncDataVersion}`
+                                    : formatTimestamp(pendingRestoreBackup.createdAt)}
+                            </div>
+                            <div className="text-muted-foreground flex items-center gap-1 flex-wrap">
+                                <span>{getReasonLabel(pendingRestoreBackup.reason)}</span>
+                                {pendingRestoreBackup.syncDataVersion && (
+                                    <>
+                                        <span aria-hidden="true">·</span>
+                                        <span>{formatTimestamp(pendingRestoreBackup.createdAt)}</span>
+                                    </>
+                                )}
+                                {pendingRestoreBackup.sourceAppVersion && pendingRestoreBackup.targetAppVersion && (
+                                    <>
+                                        <span aria-hidden="true">·</span>
+                                        <span>
+                                            {t('cloudSync.localBackups.versionChange', {
+                                                from: pendingRestoreBackup.sourceAppVersion,
+                                                to: pendingRestoreBackup.targetAppVersion,
+                                            })}
+                                        </span>
+                                    </>
+                                )}
                             </div>
                             <div className="text-muted-foreground">
                                 {t('cloudSync.localBackups.counts', {
@@ -1172,6 +1200,17 @@ const SyncDashboard: React.FC<SyncDashboardProps> = ({
     // Clear local data dialog
     const [showClearLocalDialog, setShowClearLocalDialog] = useState(false);
 
+    // Sync-blocked banner (Task 7) + force-push confirmation modal (Task 8)
+    const [blockedFinding, setBlockedFinding] = useState<Extract<ShrinkFinding, { suspicious: true }> | null>(null);
+    const [showForcePushConfirm, setShowForcePushConfirm] = useState(false);
+
+    // Ref for scrolling to LocalBackupsPanel when the banner's Restore button is clicked
+    const localBackupsRef = useRef<HTMLDivElement>(null);
+
+    // Active tab state — lets the banner's "Restore" button switch to the
+    // local-backups tab without a separate DOM query.
+    const [activeTab, setActiveTab] = useState<'providers' | 'status'>('providers');
+
     const ensureSyncablePayload = useCallback(
         (payload: SyncPayload): boolean => {
             const encryptedCredentialPaths = findSyncPayloadEncryptedCredentialPaths(payload);
@@ -1190,6 +1229,35 @@ const SyncDashboard: React.FC<SyncDashboardProps> = ({
         }
     }, [sync.currentConflict]);
 
+    // Subscribe to sync events to show/clear the blocked-shrink banner.
+    // Destructure the stable useCallback reference so the effect runs once on
+    // mount rather than re-subscribing on every render when `sync` object ref changes.
+    const { subscribeToEvents, getShrinkBlockedFinding } = sync;
+
+    // Hydrate from current manager state in case a shrink-block happened
+    // before this component mounted (e.g., auto-sync ran while the user
+    // was on a different tab). Without this, the banner only shows
+    // blocks that occur after Settings is open.
+    useEffect(() => {
+        const existing = getShrinkBlockedFinding();
+        if (existing) {
+            setBlockedFinding(existing);
+        }
+    }, [getShrinkBlockedFinding]);
+
+    useEffect(() => {
+        const unsub = subscribeToEvents((event) => {
+            if (event.type === 'SYNC_BLOCKED_SHRINK') {
+                if (event.finding.suspicious) {
+                    setBlockedFinding(event.finding);
+                }
+            } else if (event.type === 'SYNC_BLOCKED_CLEARED') {
+                setBlockedFinding(null);
+            }
+        });
+        return unsub;
+    }, [subscribeToEvents]);
+
     // If we have a master key but we're still locked (e.g. older installs),
     // prompt once and persist the password via safeStorage.
     useEffect(() => {
@@ -1441,9 +1509,30 @@ const SyncDashboard: React.FC<SyncDashboardProps> = ({
                 // window's push, not ours.
                 const localPayload = onBuildPayload();
                 if (!ensureSyncablePayload(localPayload)) return;
+
+                let results: Map<CloudProvider, SyncResult> | null = null;
                 await withRestoreBarrier(async () => {
-                    await sync.syncNow(localPayload);
+                    results = await sync.syncNow(localPayload, { overrideShrink: true });
                 });
+
+                if (results) {
+                    // Apply any merged payload BEFORE closing the modal so local state
+                    // reflects what's now on cloud (in case remote changed during the merge).
+                    for (const result of (results as Map<CloudProvider, SyncResult>).values()) {
+                        if (result.mergedPayload) {
+                            await Promise.resolve(onApplyPayload(result.mergedPayload));
+                            break;
+                        }
+                    }
+                    const allOk = Array.from((results as Map<CloudProvider, SyncResult>).values()).every((r) => r.success);
+                    if (!allOk) {
+                        const firstError = Array.from((results as Map<CloudProvider, SyncResult>).values())
+                            .find((r) => !r.success)?.error
+                            ?? t('common.unknownError');
+                        toast.error(firstError, t('cloudSync.resolve.failedTitle'));
+                        return; // KEEP the modal open so user can retry / pick USE_REMOTE
+                    }
+                }
                 toast.success(t('cloudSync.resolve.uploaded'));
             }
             setShowConflictModal(false);
@@ -1554,7 +1643,20 @@ const SyncDashboard: React.FC<SyncDashboardProps> = ({
                 </div>
             </div>
 
-            <Tabs defaultValue="providers" className="space-y-4">
+            {blockedFinding && (
+                <SyncBlockedBanner
+                    finding={blockedFinding}
+                    onRestore={() => {
+                        setActiveTab('status');
+                        requestAnimationFrame(() => {
+                            localBackupsRef.current?.scrollIntoView({ behavior: 'smooth', block: 'start' });
+                        });
+                    }}
+                    onForcePush={() => setShowForcePushConfirm(true)}
+                />
+            )}
+
+            <Tabs value={activeTab} onValueChange={(v) => setActiveTab(v as 'providers' | 'status')} className="space-y-4">
                 <TabsList className="grid w-full grid-cols-2">
                     <TabsTrigger value="providers">{t('cloudSync.providers.title')}</TabsTrigger>
                     <TabsTrigger value="status">{t('cloudSync.status.title')}</TabsTrigger>
@@ -1739,9 +1841,11 @@ const SyncDashboard: React.FC<SyncDashboardProps> = ({
                         </div>
                     )}
 
-                    <LocalBackupsPanel
-                        onApplyPayload={onApplyPayload}
-                    />
+                    <div ref={localBackupsRef}>
+                        <LocalBackupsPanel
+                            onApplyPayload={onApplyPayload}
+                        />
+                    </div>
 
                     {/* Clear Local Data */}
                     <div className="p-4 rounded-lg border border-destructive/30 bg-destructive/5">
@@ -2361,6 +2465,69 @@ const SyncDashboard: React.FC<SyncDashboardProps> = ({
                     </DialogFooter>
                 </DialogContent>
             </Dialog>
+
+            {/* Force-push confirmation modal (Task 8) */}
+            {showForcePushConfirm && blockedFinding && (
+                <Dialog open onOpenChange={(open) => !open && setShowForcePushConfirm(false)}>
+                    <DialogContent>
+                        <DialogHeader>
+                            <DialogTitle>{t('sync.forcePush.title')}</DialogTitle>
+                        </DialogHeader>
+                        <p className="text-sm">
+                            {t('sync.forcePush.body', {
+                                lost: blockedFinding.lost,
+                                entityType: t(`sync.entityType.${blockedFinding.entityType}`),
+                            })}
+                        </p>
+                        <DialogFooter>
+                            <Button variant="outline" onClick={() => setShowForcePushConfirm(false)}>
+                                {t('sync.forcePush.cancel')}
+                            </Button>
+                            <Button
+                                variant="destructive"
+                                onClick={async () => {
+                                    const localPayload = onBuildPayload();
+                                    if (!ensureSyncablePayload(localPayload)) {
+                                        setShowForcePushConfirm(false);
+                                        return;
+                                    }
+                                    setShowForcePushConfirm(false);
+                                    try {
+                                        const results = await sync.syncNow(localPayload, { overrideShrink: true });
+
+                                        // Apply any merged payload BEFORE clearing the banner. If a merge happened
+                                        // during force-push (remote changed), the merged result is what the cloud
+                                        // now has — applying it to local state prevents the next sync from
+                                        // re-deleting the remote additions we just merged in.
+                                        for (const result of results.values()) {
+                                            if (result.mergedPayload) {
+                                                await Promise.resolve(onApplyPayload(result.mergedPayload));
+                                                break; // All providers share the same merged payload
+                                            }
+                                        }
+
+                                        const allOk = Array.from(results.values()).every((r) => r.success);
+                                        if (allOk) {
+                                            setBlockedFinding(null);
+                                        } else {
+                                            // Surface the failure but KEEP the banner so the user can retry or
+                                            // restore. Find the first error string to display.
+                                            const firstError = Array.from(results.values())
+                                                .find((r) => !r.success)
+                                                ?.error ?? t('sync.toast.errorTitle');
+                                            toast.error(firstError, t('sync.toast.errorTitle'));
+                                        }
+                                    } catch (err) {
+                                        toast.error(String(err), t('sync.toast.errorTitle'));
+                                    }
+                                }}
+                            >
+                                {t('sync.forcePush.confirm')}
+                            </Button>
+                        </DialogFooter>
+                    </DialogContent>
+                </Dialog>
+            )}
         </div>
     );
 };

components/SyncStatusButton.tsx

@@ -136,7 +136,13 @@ export const SyncStatusButton: React.FC<SyncStatusButtonProps> = ({
     // Determine overall status for the button indicator
     const getOverallStatus = (): StatusIndicatorProps['status'] => {
         if (sync.overallSyncStatus === 'syncing') return 'syncing';
-        if (sync.overallSyncStatus === 'error' || sync.overallSyncStatus === 'conflict') return 'error';
+        if (
+            sync.overallSyncStatus === 'error' ||
+            sync.overallSyncStatus === 'conflict' ||
+            sync.overallSyncStatus === 'blocked'
+        ) {
+            return 'error';
+        }
         if (sync.overallSyncStatus === 'synced') return 'synced';
         return 'none';
     };

components/Terminal.tsx

@@ -49,6 +49,7 @@ import { ZmodemProgressIndicator } from "./terminal/ZmodemProgressIndicator";
 import { useZmodemTransfer } from "./terminal/hooks/useZmodemTransfer";
 import { createTerminalSessionStarters, type PendingAuth } from "./terminal/runtime/createTerminalSessionStarters";
 import { createXTermRuntime, primaryFontFamily, type XTermRuntime } from "./terminal/runtime/createXTermRuntime";
+import { shouldPreserveTerminalFocusOnMouseDown } from "./terminal/toolbarFocus";
 import { preserveTerminalViewportInScrollback } from "./terminal/clearTerminalViewport";
 import { XTERM_PERFORMANCE_CONFIG } from "../infrastructure/config/xtermPerformance";
 import { useTerminalSearch } from "./terminal/hooks/useTerminalSearch";
@@ -620,6 +621,12 @@ const TerminalComponent: React.FC<TerminalProps> = ({
     termRef.current?.focus();
   }, []);
 
+  const handleTopOverlayMouseDownCapture = useCallback((e: React.MouseEvent<HTMLDivElement>) => {
+    if (e.button !== 0) return;
+    if (!shouldPreserveTerminalFocusOnMouseDown(e.target)) return;
+    e.preventDefault();
+  }, []);
+
   // Subscribe to custom theme changes so editing triggers re-render
   const customThemes = useCustomThemes();
   const hasFontSizeOverride = host.fontSizeOverride === true || (host.fontSizeOverride === undefined && host.fontSize != null);
@@ -1706,6 +1713,7 @@ const TerminalComponent: React.FC<TerminalProps> = ({
         <div className="absolute left-0 right-0 top-0 z-20 pointer-events-none">
           <div
             className="flex items-center gap-1 px-2 py-0.5 backdrop-blur-md pointer-events-auto min-w-0"
+            onMouseDownCapture={handleTopOverlayMouseDownCapture}
             style={{
               backgroundColor: 'var(--terminal-ui-bg)',
               color: 'var(--terminal-ui-fg)',

components/TerminalLayer.tsx

@@ -429,6 +429,8 @@ interface TerminalLayerProps {
   sessionLogsEnabled?: boolean;
   sessionLogsDir?: string;
   sessionLogsFormat?: string;
+  closeSidePanelRef?: React.MutableRefObject<(() => void) | null>;
+  activeSidePanelTabRef?: React.MutableRefObject<string | null>;
 }
 
 const TerminalLayerInner: React.FC<TerminalLayerProps> = ({
@@ -482,6 +484,8 @@ const TerminalLayerInner: React.FC<TerminalLayerProps> = ({
   sessionLogsEnabled,
   sessionLogsDir,
   sessionLogsFormat,
+  closeSidePanelRef,
+  activeSidePanelTabRef,
 }) => {
   // Subscribe to activeTabId from external store
   const activeTabId = useActiveTabId();
@@ -662,6 +666,9 @@ const TerminalLayerInner: React.FC<TerminalLayerProps> = ({
   // Whether side panel is open for the currently active tab and which sub-panel
   const isSidePanelOpenForCurrentTab = activeTabId ? sidePanelOpenTabs.has(activeTabId) : false;
   const activeSidePanelTab = activeTabId ? sidePanelOpenTabs.get(activeTabId) ?? null : null;
+  if (activeSidePanelTabRef) {
+    activeSidePanelTabRef.current = activeSidePanelTab;
+  }
 
   // Legacy compatibility helpers for SFTP-specific logic
   const isSftpOpenForCurrentTab = activeSidePanelTab === 'sftp';
@@ -1258,9 +1265,25 @@ const TerminalLayerInner: React.FC<TerminalLayerProps> = ({
     }
   }, [activeWorkspace?.focusedSessionId, activeSession?.id, terminalBackend]);
 
+  const refocusTerminalSession = useCallback((sessionId?: string | null) => {
+    if (!sessionId) return;
+
+    const focusTarget = () => {
+      const pane = document.querySelector(`[data-session-id="${sessionId}"]`);
+      const textarea = pane?.querySelector('textarea.xterm-helper-textarea') as HTMLTextAreaElement | null;
+      textarea?.focus();
+    };
+
+    requestAnimationFrame(() => {
+      focusTarget();
+      setTimeout(focusTarget, 50);
+    });
+  }, []);
+
   // Close the entire side panel for the current tab
   const handleCloseSidePanel = useCallback(() => {
     if (!activeTabId) return;
+    const sessionIdToRefocus = activeWorkspace?.focusedSessionId ?? activeSession?.id;
     setSidePanelOpenTabs(prev => {
       const next = new Map(prev);
       next.delete(activeTabId);
@@ -1283,7 +1306,16 @@ const TerminalLayerInner: React.FC<TerminalLayerProps> = ({
       next.delete(activeTabId);
       return next;
     });
-  }, [activeTabId]);
+    refocusTerminalSession(sessionIdToRefocus);
+  }, [activeTabId, activeWorkspace?.focusedSessionId, activeSession?.id, refocusTerminalSession]);
+
+  useEffect(() => {
+    if (!closeSidePanelRef) return;
+    closeSidePanelRef.current = handleCloseSidePanel;
+    return () => {
+      closeSidePanelRef.current = null;
+    };
+  }, [closeSidePanelRef, handleCloseSidePanel]);
 
   // Switch side panel to a specific tab (or toggle if already on that tab)
   const handleSwitchSidePanelTab = useCallback((tab: SidePanelTab) => {
@@ -2402,14 +2434,7 @@ const TerminalLayerInner: React.FC<TerminalLayerProps> = ({
             onSend={handleComposeSend}
             onClose={() => {
               setIsComposeBarOpen(false);
-              // Refocus the terminal pane (matching solo-session behavior)
-              if (focusedSessionId) {
-                requestAnimationFrame(() => {
-                  const pane = document.querySelector(`[data-session-id="${focusedSessionId}"]`);
-                  const textarea = pane?.querySelector('textarea.xterm-helper-textarea') as HTMLTextAreaElement | null;
-                  textarea?.focus();
-                });
-              }
+              refocusTerminalSession(focusedSessionId);
             }}
             isBroadcastEnabled={isBroadcastEnabled?.(activeWorkspace.id)}
             themeColors={composeBarThemeColors}

components/TopTabs.tsx

@@ -304,11 +304,23 @@ const TopTabsInner: React.FC<TopTabsProps> = ({
     updateScrollState();
     const container = tabsContainerRef.current;
     if (container) {
+      // Translate vertical wheel to horizontal scroll so users can reach
+      // off-screen tabs with a standard mouse wheel. Trackpad gestures that
+      // already carry horizontal delta are left alone so native two-finger
+      // swiping still works.
+      const handleWheel = (e: WheelEvent) => {
+        if (e.deltaY !== 0 && e.deltaX === 0) {
+          e.preventDefault();
+          container.scrollLeft += e.deltaY;
+        }
+      };
       container.addEventListener('scroll', updateScrollState);
+      container.addEventListener('wheel', handleWheel, { passive: false });
       const resizeObserver = new ResizeObserver(updateScrollState);
       resizeObserver.observe(container);
       return () => {
         container.removeEventListener('scroll', updateScrollState);
+        container.removeEventListener('wheel', handleWheel);
         resizeObserver.disconnect();
       };
     }

components/VaultView.tsx

@@ -36,7 +36,7 @@ import { useStoredViewMode } from "../application/state/useStoredViewMode";
 import { useStoredBoolean } from "../application/state/useStoredBoolean";
 import { useTreeExpandedState } from "../application/state/useTreeExpandedState";
 import { resolveGroupDefaults, applyGroupDefaults } from "../domain/groupConfig";
-import { getEffectiveHostDistro, sanitizeHost } from "../domain/host";
+import { getEffectiveHostDistro, sanitizeHost, upsertHostById } from "../domain/host";
 import { importVaultHostsFromText, exportHostsToCsvWithStats } from "../domain/vaultImport";
 import type { VaultImportFormat } from "../domain/vaultImport";
 import {
@@ -2941,13 +2941,7 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
           groupDefaults={editingHostGroupDefaults}
           groupConfigs={groupConfigs}
           onSave={(host) => {
-            // Check if host already exists in the list (for updates vs. new/duplicate)
-            const hostExists = hosts.some((h) => h.id === host.id);
-            onUpdateHosts(
-              hostExists
-                ? hosts.map((h) => (h.id === host.id ? host : h))
-                : [...hosts, host],
-            );
+            onUpdateHosts(upsertHostById(hosts, host));
             setIsHostPanelOpen(false);
             setEditingHost(null);
             setNewHostGroupPath(null);
@@ -2973,15 +2967,15 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
           allTags={allTags}
           groups={allGroupPaths}
           onSave={(host) => {
-            onUpdateHosts(
-              hosts.map((h) => (h.id === host.id ? host : h)),
-            );
+            onUpdateHosts(upsertHostById(hosts, host));
             setIsHostPanelOpen(false);
             setEditingHost(null);
+            setNewHostGroupPath(null);
           }}
           onCancel={() => {
             setIsHostPanelOpen(false);
             setEditingHost(null);
+            setNewHostGroupPath(null);
           }}
           layout="inline"
         />

components/sync/SyncBlockedBanner.tsx

@@ -0,0 +1,51 @@
+import React from 'react';
+import { AlertTriangle } from 'lucide-react';
+import type { ShrinkFinding } from '../../domain/syncGuards';
+import { Button } from '../ui/button';
+import { useI18n } from '../../application/i18n/I18nProvider';
+
+interface Props {
+  finding: Extract<ShrinkFinding, { suspicious: true }>;
+  onRestore: () => void;
+  onForcePush: () => void;
+}
+
+export const SyncBlockedBanner: React.FC<Props> = ({ finding, onRestore, onForcePush }) => {
+  const { t } = useI18n();
+  const entityLabel = t(`sync.entityType.${finding.entityType}`);
+  const percent = finding.baseCount > 0 ? Math.round((finding.lost / finding.baseCount) * 100) : 0;
+
+  const reasonText = finding.reason === 'bulk-shrink'
+    ? t('sync.blocked.reason.bulkShrink', {
+        lost: finding.lost,
+        baseCount: finding.baseCount,
+        entityType: entityLabel,
+        percent,
+      })
+    : t('sync.blocked.reason.largeShrink', {
+        lost: finding.lost,
+        entityType: entityLabel,
+      });
+
+  return (
+    <div
+      role="alert"
+      className="flex flex-col gap-2 rounded-md border border-amber-500/40 bg-amber-500/10 p-4"
+    >
+      <div className="flex items-center gap-2 font-semibold">
+        <AlertTriangle className="h-4 w-4 text-amber-500" />
+        <span>{t('sync.blocked.title')}</span>
+      </div>
+      <p className="text-sm">{reasonText}</p>
+      <p className="text-xs opacity-70">{t('sync.blocked.detail')}</p>
+      <div className="flex gap-2">
+        <Button variant="default" size="sm" onClick={onRestore}>
+          {t('sync.blocked.restoreButton')}
+        </Button>
+        <Button variant="outline" size="sm" onClick={onForcePush}>
+          {t('sync.blocked.forcePushButton')}
+        </Button>
+      </div>
+    </div>
+  );
+};

components/terminal/autocomplete/useTerminalAutocomplete.ts

@@ -690,7 +690,9 @@ export function useTerminalAutocomplete(
         }
       }
 
-      // Tab: accept selected popup suggestion, or accept ghost text
+      // Tab: accept selected popup suggestion. Ghost text is accepted via → only —
+      // letting Tab pass through lets the shell's native completion (bash/zsh) run,
+      // 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();
@@ -698,16 +700,10 @@ export function useTerminalAutocomplete(
           if (selected) insertSuggestion(selected, false);
           return false;
         }
+        // Hide stale ghost text before Tab reaches the shell — the shell's
+        // completion will rewrite the line and the old ghost would mislead.
         if (ghost?.isVisible()) {
-          e.preventDefault();
-          const ghostText = ghost.getGhostText();
-          if (ghostText) {
-            writeToTerminal(ghostText);
-            lastAcceptedCommandRef.current = ghost.getSuggestion();
-            ghost.hide();
-            clearState();
-          }
-          return false;
+          ghost.hide();
         }
       }
 

components/terminal/toolbarFocus.test.ts

@@ -0,0 +1,64 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { shouldPreserveTerminalFocusOnMouseDown } from "./toolbarFocus.ts";
+
+test("preserves terminal focus for non-editable overlay clicks", () => {
+  const buttonLikeTarget = {
+    tagName: "button",
+    isContentEditable: false,
+    closest() {
+      return null;
+    },
+    getAttribute() {
+      return null;
+    },
+  };
+
+  assert.equal(shouldPreserveTerminalFocusOnMouseDown(buttonLikeTarget as unknown as EventTarget), true);
+});
+
+test("allows native focus for direct editable targets", () => {
+  const inputTarget = {
+    tagName: "input",
+    isContentEditable: false,
+    closest() {
+      return null;
+    },
+    getAttribute() {
+      return null;
+    },
+  };
+
+  assert.equal(shouldPreserveTerminalFocusOnMouseDown(inputTarget as unknown as EventTarget), false);
+});
+
+test("allows native focus for descendants inside editable controls", () => {
+  const nestedTarget = {
+    tagName: "span",
+    isContentEditable: false,
+    closest(selector: string) {
+      return selector.includes("input") ? { tagName: "INPUT" } : null;
+    },
+    getAttribute() {
+      return null;
+    },
+  };
+
+  assert.equal(shouldPreserveTerminalFocusOnMouseDown(nestedTarget as unknown as EventTarget), false);
+});
+
+test("allows native focus for contenteditable regions", () => {
+  const editableTarget = {
+    tagName: "div",
+    isContentEditable: false,
+    closest() {
+      return null;
+    },
+    getAttribute(name: string) {
+      return name === "contenteditable" ? "true" : null;
+    },
+  };
+
+  assert.equal(shouldPreserveTerminalFocusOnMouseDown(editableTarget as unknown as EventTarget), false);
+});

components/terminal/toolbarFocus.ts

@@ -0,0 +1,44 @@
+type FocusTargetLike = {
+  tagName?: string | null;
+  isContentEditable?: boolean;
+  closest?: (selector: string) => unknown;
+  getAttribute?: (name: string) => string | null;
+};
+
+const EDITABLE_SELECTOR = 'input, textarea, select, [contenteditable=""], [contenteditable="true"], [role="textbox"]';
+
+/**
+ * The terminal's top overlay sits above the xterm textarea. Pointer clicks on
+ * that layer should usually keep focus in the terminal so typing can continue.
+ * Only allow native focus changes for genuinely editable controls.
+ */
+export const shouldPreserveTerminalFocusOnMouseDown = (target: EventTarget | null): boolean => {
+  if (!target || typeof target !== "object") return true;
+
+  const candidate = target as FocusTargetLike;
+  const tagName = typeof candidate.tagName === "string"
+    ? candidate.tagName.toUpperCase()
+    : "";
+
+  if (tagName === "INPUT" || tagName === "TEXTAREA" || tagName === "SELECT") {
+    return false;
+  }
+
+  if (candidate.isContentEditable) {
+    return false;
+  }
+
+  if (typeof candidate.getAttribute === "function") {
+    const contentEditable = candidate.getAttribute("contenteditable");
+    const role = candidate.getAttribute("role");
+    if (contentEditable === "" || contentEditable === "true" || role === "textbox") {
+      return false;
+    }
+  }
+
+  if (typeof candidate.closest === "function" && candidate.closest(EDITABLE_SELECTOR)) {
+    return false;
+  }
+
+  return true;
+};

domain/host.test.ts

@@ -0,0 +1,51 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import type { Host } from "./models.ts";
+import { upsertHostById } from "./host.ts";
+
+const makeHost = (overrides: Partial<Host> = {}): Host => ({
+  id: "host-1",
+  label: "Primary Host",
+  hostname: "127.0.0.1",
+  port: 22,
+  username: "root",
+  authType: "password",
+  createdAt: 1,
+  protocol: "ssh",
+  ...overrides,
+});
+
+test("upsertHostById updates an existing host in place", () => {
+  const existing = makeHost();
+  const updated = makeHost({ label: "Updated Host" });
+
+  assert.deepEqual(upsertHostById([existing], updated), [updated]);
+});
+
+test("upsertHostById appends a duplicated host with a fresh id", () => {
+  const existing = makeHost({
+    id: "serial-original",
+    label: "Serial Config",
+    protocol: "serial",
+    hostname: "/dev/ttyUSB0",
+    port: 115200,
+    serialConfig: {
+      path: "/dev/ttyUSB0",
+      baudRate: 115200,
+      dataBits: 8,
+      stopBits: 1,
+      parity: "none",
+      flowControl: "none",
+      localEcho: false,
+      lineMode: false,
+    },
+  });
+  const duplicate = makeHost({
+    ...existing,
+    id: "serial-duplicate",
+    label: "Serial Config (copy)",
+  });
+
+  assert.deepEqual(upsertHostById([existing], duplicate), [existing, duplicate]);
+});

domain/host.ts

@@ -153,6 +153,13 @@ export const formatHostPort = (hostname: string, port?: number | null): string =
   return `${display}:${port}`;
 };
 
+export const upsertHostById = (hosts: Host[], host: Host): Host[] => {
+  const hostExists = hosts.some((entry) => entry.id === host.id);
+  return hostExists
+    ? hosts.map((entry) => (entry.id === host.id ? host : entry))
+    : [...hosts, host];
+};
+
 export const sanitizeHost = (host: Host): Host => {
   const cleanHostname = (host.hostname || '').split(/\s+/)[0];
   const cleanDistro = normalizeDistroId(host.distro);

domain/sync.ts

@@ -1,10 +1,12 @@
 /**
  * Cloud Sync Domain Types & Interfaces
- * 
+ *
  * Zero-Knowledge Encrypted Multi-Cloud Sync System
  * Supports: GitHub Gist, Google Drive, Microsoft OneDrive, WebDAV, S3 Compatible
  */
 
+import type { ShrinkFinding } from './syncGuards';
+
 // ============================================================================
 // Security State Machine
 // ============================================================================
@@ -22,10 +24,11 @@ export type SecurityState =
  * Sync Operation State Machine
  * Tracks the current sync operation status
  */
-export type SyncState = 
+export type SyncState =
   | 'IDLE'       // Waiting for sync trigger
   | 'SYNCING'    // Active sync operation in progress
   | 'CONFLICT'   // Version conflict detected - needs resolution
+  | 'BLOCKED'    // Outgoing payload would delete too much — user must choose restore or force-push
   | 'ERROR';     // Operation failed - needs attention
 
 /**
@@ -284,6 +287,10 @@ export interface SyncResult {
   conflictDetected?: boolean;
   /** Present when action === 'merge'; caller should apply this to update local state */
   mergedPayload?: import('./sync').SyncPayload;
+  /** True when a shrink-detection guard blocked the upload */
+  shrinkBlocked?: boolean;
+  /** The finding that triggered the shrink block or force-push */
+  finding?: ShrinkFinding;
 }
 
 /**
@@ -351,10 +358,13 @@ export type SyncEvent =
   | { type: 'SYNC_COMPLETED'; provider: CloudProvider; result: SyncResult }
   | { type: 'SYNC_ERROR'; provider: CloudProvider; error: string }
   | { type: 'CONFLICT_DETECTED'; conflict: ConflictInfo }
+  | { type: 'SYNC_BLOCKED_SHRINK'; provider: CloudProvider; finding: ShrinkFinding }
+  | { type: 'SYNC_FORCED'; provider: CloudProvider; finding: ShrinkFinding }
   | { type: 'CONFLICT_RESOLVED'; resolution: ConflictResolution }
   | { type: 'AUTH_REQUIRED'; provider: CloudProvider }
   | { type: 'AUTH_COMPLETED'; provider: CloudProvider; account: ProviderAccount }
-  | { type: 'SECURITY_STATE_CHANGED'; state: SecurityState };
+  | { type: 'SECURITY_STATE_CHANGED'; state: SecurityState }
+  | { type: 'SYNC_BLOCKED_CLEARED' };
 
 // ============================================================================
 // Storage Keys

domain/syncGuards.test.ts

@@ -0,0 +1,139 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { detectSuspiciousShrink } from "./syncGuards.ts";
+import type { SyncPayload } from "./sync.ts";
+
+function payload(overrides: Partial<SyncPayload> = {}): SyncPayload {
+  return {
+    hosts: [],
+    keys: [],
+    identities: [],
+    snippets: [],
+    customGroups: [],
+    snippetPackages: [],
+    knownHosts: [],
+    portForwardingRules: [],
+    groupConfigs: [],
+    settings: undefined,
+    syncedAt: 0,
+    ...overrides,
+  };
+}
+
+function hosts(n: number): SyncPayload["hosts"] {
+  return Array.from({ length: n }, (_, i) => ({
+    id: `h${i}`,
+    label: `h${i}`,
+    hostname: `h${i}.example`,
+    port: 22,
+    username: "root",
+    protocol: "ssh",
+  })) as SyncPayload["hosts"];
+}
+
+test("null base → not suspicious (first sync / null after re-auth)", () => {
+  const result = detectSuspiciousShrink(payload({ hosts: hosts(1) }), null);
+  assert.deepEqual(result, { suspicious: false });
+});
+
+test("no shrink — same counts → not suspicious", () => {
+  const base = payload({ hosts: hosts(5) });
+  const out = payload({ hosts: hosts(5) });
+  assert.deepEqual(detectSuspiciousShrink(out, base), { suspicious: false });
+});
+
+test("growth only → not suspicious", () => {
+  const base = payload({ hosts: hosts(5) });
+  const out = payload({ hosts: hosts(10) });
+  assert.deepEqual(detectSuspiciousShrink(out, base), { suspicious: false });
+});
+
+test("shrink under both thresholds → not suspicious (delete 2 of 4)", () => {
+  const base = payload({ hosts: hosts(4) });
+  const out = payload({ hosts: hosts(2) });
+  assert.deepEqual(detectSuspiciousShrink(out, base), { suspicious: false });
+});
+
+test("bulk-shrink 50% AND absolute 3 — exactly at threshold → suspicious", () => {
+  const base = payload({ hosts: hosts(6) });
+  const out = payload({ hosts: hosts(3) });
+  assert.deepEqual(detectSuspiciousShrink(out, base), {
+    suspicious: true,
+    reason: "bulk-shrink",
+    entityType: "hosts",
+    baseCount: 6,
+    outgoingCount: 3,
+    lost: 3,
+  });
+});
+
+test("bulk-shrink 50% but absolute 2 → not suspicious (absolute gate)", () => {
+  const base = payload({ hosts: hosts(4) });
+  const out = payload({ hosts: hosts(2) });
+  assert.deepEqual(detectSuspiciousShrink(out, base), { suspicious: false });
+});
+
+test("bulk-shrink 40% absolute 4 → not suspicious (ratio gate)", () => {
+  const base = payload({ hosts: hosts(10) });
+  const out = payload({ hosts: hosts(6) });
+  assert.deepEqual(detectSuspiciousShrink(out, base), { suspicious: false });
+});
+
+test("large-shrink absolute 10 regardless of ratio → suspicious", () => {
+  const base = payload({ hosts: hosts(100) });
+  const out = payload({ hosts: hosts(90) });
+  assert.deepEqual(detectSuspiciousShrink(out, base), {
+    suspicious: true,
+    reason: "large-shrink",
+    entityType: "hosts",
+    baseCount: 100,
+    outgoingCount: 90,
+    lost: 10,
+  });
+});
+
+test("dual-trigger (large-shrink AND bulk-shrink both satisfied) → reason is 'large-shrink'", () => {
+  // base=20, lost=10: satisfies large-shrink (>=10) AND bulk-shrink (50%, >=3)
+  const base = payload({ hosts: hosts(20) });
+  const out = payload({ hosts: hosts(10) });
+  const result = detectSuspiciousShrink(out, base);
+  assert.equal(result.suspicious, true);
+  if (result.suspicious) assert.equal(result.reason, "large-shrink");
+});
+
+test("multiple entity types shrinking — returns first in declaration order (hosts before keys)", () => {
+  const base = payload({ hosts: hosts(6), keys: Array.from({ length: 6 }, (_, i) => ({ id: `k${i}`, label: `k${i}`, privateKey: "x" })) as SyncPayload["keys"] });
+  const out = payload({ hosts: hosts(3), keys: Array.from({ length: 3 }, (_, i) => ({ id: `k${i}`, label: `k${i}`, privateKey: "x" })) as SyncPayload["keys"] });
+  const result = detectSuspiciousShrink(out, base);
+  assert.equal(result.suspicious, true);
+  if (result.suspicious) assert.equal(result.entityType, "hosts");
+});
+
+test("only non-hosts entity shrinks → reports that entity", () => {
+  const snippets = (n: number) => Array.from({ length: n }, (_, i) => ({ id: `s${i}`, label: `s${i}`, command: "" })) as SyncPayload["snippets"];
+  const base = payload({ snippets: snippets(10) });
+  const out = payload({ snippets: snippets(0) });
+  const result = detectSuspiciousShrink(out, base);
+  assert.equal(result.suspicious, true);
+  if (result.suspicious) {
+    assert.equal(result.entityType, "snippets");
+    assert.equal(result.reason, "large-shrink");
+  }
+});
+
+test("knownHosts shrink triggers (security-sensitive)", () => {
+  const kh = (n: number) => Array.from({ length: n }, (_, i) => ({ id: `kh${i}`, hostname: `h${i}`, port: 22, keyType: "rsa", fingerprint: "x" })) as unknown as SyncPayload["knownHosts"];
+  const base = payload({ knownHosts: kh(12) });
+  const out = payload({ knownHosts: kh(2) });
+  const result = detectSuspiciousShrink(out, base);
+  assert.equal(result.suspicious, true);
+  if (result.suspicious) assert.equal(result.entityType, "knownHosts");
+});
+
+test("empty base (all zeros) — no shrink possible, returns not suspicious", () => {
+  const base = payload();
+  const out = payload({ hosts: hosts(5) });
+  // All base counts are 0; no shrink possible
+  assert.deepEqual(detectSuspiciousShrink(out, base), { suspicious: false });
+});

domain/syncGuards.ts

@@ -0,0 +1,85 @@
+import type { SyncPayload } from './sync';
+
+export type ShrinkFinding =
+  | { suspicious: false }
+  | {
+      suspicious: true;
+      reason: 'bulk-shrink' | 'large-shrink';
+      entityType:
+        | 'hosts'
+        | 'keys'
+        | 'identities'
+        | 'snippets'
+        | 'customGroups'
+        | 'snippetPackages'
+        | 'knownHosts'
+        | 'portForwardingRules'
+        | 'groupConfigs';
+      baseCount: number;
+      outgoingCount: number;
+      lost: number;
+    };
+
+// Keep in sync with all array-typed fields of SyncPayload. When a new
+// array entity type is added there, add it here too — there is no
+// compile-time check enforcing this.
+const CHECKED_ENTITIES = [
+  'hosts',
+  'keys',
+  'identities',
+  'snippets',
+  'customGroups',
+  'snippetPackages',
+  'knownHosts',
+  'portForwardingRules',
+  'groupConfigs',
+] as const;
+
+type CheckedEntityType = typeof CHECKED_ENTITIES[number];
+
+const BULK_SHRINK_RATIO = 0.5;
+const BULK_SHRINK_MIN_ABSOLUTE = 3;
+const LARGE_SHRINK_ABSOLUTE = 10;
+
+function countOf(p: SyncPayload, key: CheckedEntityType): number {
+  const v = p[key];
+  return Array.isArray(v) ? v.length : 0;
+}
+
+export function detectSuspiciousShrink(
+  outgoing: SyncPayload,
+  base: SyncPayload | null,
+): ShrinkFinding {
+  if (!base) return { suspicious: false };
+
+  for (const entityType of CHECKED_ENTITIES) {
+    const baseCount = countOf(base, entityType);
+    const outgoingCount = countOf(outgoing, entityType);
+    const lost = baseCount - outgoingCount;
+    if (lost <= 0) continue;
+
+    if (lost >= LARGE_SHRINK_ABSOLUTE) {
+      return {
+        suspicious: true,
+        reason: 'large-shrink',
+        entityType,
+        baseCount,
+        outgoingCount,
+        lost,
+      };
+    }
+
+    if (baseCount > 0 && lost / baseCount >= BULK_SHRINK_RATIO && lost >= BULK_SHRINK_MIN_ABSOLUTE) {
+      return {
+        suspicious: true,
+        reason: 'bulk-shrink',
+        entityType,
+        baseCount,
+        outgoingCount,
+        lost,
+      };
+    }
+  }
+
+  return { suspicious: false };
+}

electron-builder.config.cjs

@@ -29,6 +29,7 @@ module.exports = {
         'node_modules/node-pty/**/*',
         'node_modules/ssh2/**/*',
         'node_modules/cpu-features/**/*',
+        'node_modules/@vscode/windows-process-tree/**/*',
         'node_modules/@zed-industries/claude-agent-acp/**/*',
         'node_modules/@agentclientprotocol/sdk/**/*',
         'node_modules/@anthropic-ai/claude-agent-sdk/**/*',

electron/bridges/ptyProcessTree.cjs

@@ -0,0 +1,89 @@
+const { execFile } = require("node:child_process");
+
+function createProcessTree({ platform, listPosix, listWindows } = {}) {
+  const sessionPidMap = new Map();
+
+  function registerPid(sessionId, pid) {
+    if (!sessionId || typeof pid !== "number") return;
+    if (sessionPidMap.has(sessionId) && sessionPidMap.get(sessionId) !== pid) {
+      console.warn(
+        `[ptyProcessTree] sessionId "${sessionId}" already registered with pid ${sessionPidMap.get(sessionId)}; overwriting with ${pid}.`,
+      );
+    }
+    sessionPidMap.set(sessionId, pid);
+  }
+
+  function unregisterPid(sessionId) {
+    sessionPidMap.delete(sessionId);
+  }
+
+  async function getChildProcesses(sessionId) {
+    const pid = sessionPidMap.get(sessionId);
+    if (!pid) return [];
+    if (platform === "win32") {
+      return listWindows ? listWindows(pid) : [];
+    }
+    return listPosix ? listPosix(pid) : [];
+  }
+
+  return { registerPid, unregisterPid, getChildProcesses };
+}
+
+function defaultListPosix(ppid) {
+  return new Promise((resolve) => {
+    // `ps -A -o pid=,ppid=,args=` works on both BSD (macOS) and GNU (Linux).
+    // `args=` shows the full command line (not truncated like `comm=`).
+    // The trailing `=` on each column suppresses the header row.
+    execFile("ps", ["-A", "-o", "pid=,ppid=,args="], (err, stdout) => {
+      if (err || typeof stdout !== "string") return resolve([]);
+      const out = [];
+      for (const line of stdout.split("\n")) {
+        const trimmed = line.trim();
+        if (!trimmed) continue;
+        const m = trimmed.match(/^(\d+)\s+(\d+)\s+(.+)$/);
+        if (!m) continue;
+        if (Number(m[2]) !== ppid) continue;
+        out.push({ pid: Number(m[1]), command: m[3].trim() });
+      }
+      resolve(out);
+    });
+  });
+}
+
+function defaultListWindows(ppid) {
+  return new Promise((resolve) => {
+    let wpt;
+    try {
+      wpt = require("@vscode/windows-process-tree");
+    } catch {
+      return resolve([]);
+    }
+    try {
+      wpt.getProcessTree(ppid, (tree) => {
+        if (!tree || !Array.isArray(tree.children)) return resolve([]);
+        resolve(tree.children.map((c) => ({ pid: c.pid, command: c.name })));
+      });
+    } catch {
+      resolve([]);
+    }
+  });
+}
+
+function createDefaultProcessTree() {
+  const platform = process.platform;
+  return createProcessTree({
+    platform,
+    listPosix: platform === "win32" ? undefined : defaultListPosix,
+    listWindows: platform === "win32" ? defaultListWindows : undefined,
+  });
+}
+
+const defaultTree = createDefaultProcessTree();
+
+module.exports = {
+  createProcessTree,
+  processTree: defaultTree,
+  registerPid: (id, pid) => defaultTree.registerPid(id, pid),
+  unregisterPid: (id) => defaultTree.unregisterPid(id),
+  getChildProcesses: (id) => defaultTree.getChildProcesses(id),
+};

electron/bridges/ptyProcessTree.test.cjs

@@ -0,0 +1,79 @@
+const test = require("node:test");
+const assert = require("node:assert/strict");
+
+const { createProcessTree } = require("./ptyProcessTree.cjs");
+
+test("getChildProcesses returns [] when session has no registered pid", async () => {
+  const tree = createProcessTree({ platform: "darwin", listPosix: async () => [] });
+  assert.deepEqual(await tree.getChildProcesses("unknown-session"), []);
+});
+
+test("getChildProcesses calls listPosix with the registered ppid and returns its result", async () => {
+  const calls = [];
+  const listPosix = async (ppid) => {
+    calls.push(ppid);
+    return [
+      { pid: 2001, command: "sleep 100" },
+      { pid: 2002, command: "node server.js" },
+    ];
+  };
+  const tree = createProcessTree({ platform: "linux", listPosix });
+  tree.registerPid("s1", 1234);
+  assert.deepEqual(await tree.getChildProcesses("s1"), [
+    { pid: 2001, command: "sleep 100" },
+    { pid: 2002, command: "node server.js" },
+  ]);
+  assert.deepEqual(calls, [1234]);
+});
+
+test("unregisterPid clears mapping", async () => {
+  const tree = createProcessTree({
+    platform: "darwin",
+    listPosix: async () => [{ pid: 9, command: "x" }],
+  });
+  tree.registerPid("s1", 1234);
+  tree.unregisterPid("s1");
+  assert.deepEqual(await tree.getChildProcesses("s1"), []);
+});
+
+test("getChildProcesses on windows uses listWindows", async () => {
+  const calls = [];
+  const listWindows = async (pid) => {
+    calls.push(pid);
+    return [{ pid: 55, command: "python.exe" }];
+  };
+  const tree = createProcessTree({ platform: "win32", listWindows });
+  tree.registerPid("s1", 3000);
+  assert.deepEqual(await tree.getChildProcesses("s1"), [{ pid: 55, command: "python.exe" }]);
+  assert.deepEqual(calls, [3000]);
+});
+
+test("getChildProcesses returns [] when listPosix missing on posix", async () => {
+  const tree = createProcessTree({ platform: "darwin" });
+  tree.registerPid("s1", 1234);
+  assert.deepEqual(await tree.getChildProcesses("s1"), []);
+});
+
+test("getChildProcesses returns [] when listWindows missing on windows", async () => {
+  const tree = createProcessTree({ platform: "win32" });
+  tree.registerPid("s1", 3000);
+  assert.deepEqual(await tree.getChildProcesses("s1"), []);
+});
+
+test("registerPid warns when overwriting an existing sessionId with a different pid", async () => {
+  const warnCalls = [];
+  const origWarn = console.warn;
+  console.warn = (...args) => warnCalls.push(args);
+  try {
+    const tree = createProcessTree({ platform: "darwin", listPosix: async () => [] });
+    tree.registerPid("s1", 1234);
+    tree.registerPid("s1", 1234); // same pid — no warn
+    tree.registerPid("s1", 5678); // different — should warn
+    assert.equal(warnCalls.length, 1);
+    assert.match(warnCalls[0][0], /s1/);
+    assert.match(warnCalls[0][0], /1234/);
+    assert.match(warnCalls[0][0], /5678/);
+  } finally {
+    console.warn = origWarn;
+  }
+});

electron/bridges/sshIdentificationCompatibility.test.cjs

@@ -0,0 +1,46 @@
+const test = require("node:test");
+const assert = require("node:assert/strict");
+
+const Protocol = require("ssh2/lib/protocol/Protocol");
+
+function parseIdentification(line) {
+  let header;
+  const protocol = new Protocol({
+    onWrite() {},
+    onError(err) {
+      throw err;
+    },
+    onHeader(nextHeader) {
+      header = nextHeader;
+    },
+  });
+
+  const data = Buffer.from(`${line}\r\n`, "latin1");
+  protocol.parse(data, 0, data.length);
+
+  assert.ok(header, "expected SSH header to be parsed");
+  return header;
+}
+
+test("ssh2 accepts an empty softwareversion for compatibility", () => {
+  const header = parseIdentification("SSH-2.0-");
+
+  assert.equal(header.versions.protocol, "2.0");
+  assert.equal(header.versions.software, "");
+  assert.equal(header.comments, undefined);
+});
+
+test("ssh2 still accepts standard identification strings", () => {
+  const header = parseIdentification("SSH-2.0-OpenSSH_9.9 Netcatty");
+
+  assert.equal(header.versions.protocol, "2.0");
+  assert.equal(header.versions.software, "OpenSSH_9.9");
+  assert.equal(header.comments, "Netcatty");
+});
+
+test("ssh2 still rejects malformed identification strings", () => {
+  assert.throws(
+    () => parseIdentification("SSH-2.0"),
+    /Invalid identification string/,
+  );
+});

electron/bridges/terminalBridge.cjs

@@ -10,6 +10,7 @@ const path = require("node:path");
 const { StringDecoder } = require("node:string_decoder");
 const pty = require("node-pty");
 const { SerialPort } = require("serialport");
+const ptyProcessTree = require("./ptyProcessTree.cjs");
 
 const sessionLogStreamManager = require("./sessionLogStreamManager.cjs");
 const { detectShellKind } = require("./ai/ptyExec.cjs");
@@ -326,6 +327,7 @@ function startLocalSession(event, payload) {
     _promptTrackTail: "",
   };
   sessions.set(sessionId, session);
+  ptyProcessTree.registerPid(sessionId, proc.pid);
 
   // Start real-time session log stream if configured
   if (payload?.sessionLog?.enabled && payload?.sessionLog?.directory) {
@@ -382,6 +384,7 @@ function startLocalSession(event, payload) {
   proc.onExit((evt) => {
     flushLocal();
     sessionLogStreamManager.stopStream(sessionId);
+    ptyProcessTree.unregisterPid(sessionId);
     sessions.delete(sessionId);
     const contents = electronModule.webContents.fromId(session.webContentsId);
     // Signal present = killed externally (show disconnected UI).
@@ -648,6 +651,7 @@ async function startTelnetSession(event, options) {
           const contents = electronModule.webContents.fromId(session.webContentsId);
           contents?.send("netcatty:exit", { sessionId, exitCode: 1, error: err.message, reason: "error" });
         }
+        ptyProcessTree.unregisterPid(sessionId);
         sessions.delete(sessionId);
       }
     });
@@ -664,6 +668,7 @@ async function startTelnetSession(event, options) {
         const contents = electronModule.webContents.fromId(session.webContentsId);
         contents?.send("netcatty:exit", { sessionId, exitCode: hadError ? 1 : 0, reason: hadError ? "error" : "closed" });
       }
+      ptyProcessTree.unregisterPid(sessionId);
       sessions.delete(sessionId);
     });
 
@@ -802,6 +807,7 @@ async function startMoshSession(event, options) {
     proc.onExit((evt) => {
       flushMosh();
       sessionLogStreamManager.stopStream(sessionId);
+      ptyProcessTree.unregisterPid(sessionId);
       sessions.delete(sessionId);
       const contents = electronModule.webContents.fromId(session.webContentsId);
       // Mosh non-zero exit typically means connection/auth failure — show error UI
@@ -931,6 +937,7 @@ async function startSerialSession(event, options) {
           sessionLogStreamManager.stopStream(sessionId);
           const contents = electronModule.webContents.fromId(session.webContentsId);
           contents?.send("netcatty:exit", { sessionId, exitCode: 1, error: err.message, reason: "error" });
+          ptyProcessTree.unregisterPid(sessionId);
           sessions.delete(sessionId);
         });
 
@@ -940,6 +947,7 @@ async function startSerialSession(event, options) {
           sessionLogStreamManager.stopStream(sessionId);
           const contents = electronModule.webContents.fromId(session.webContentsId);
           contents?.send("netcatty:exit", { sessionId, exitCode: 0, reason: "closed" });
+          ptyProcessTree.unregisterPid(sessionId);
           sessions.delete(sessionId);
         });
 
@@ -1043,6 +1051,7 @@ function closeSession(event, payload) {
   } catch (err) {
     console.warn("Close failed", err);
   }
+  ptyProcessTree.unregisterPid(payload.sessionId);
   sessions.delete(payload.sessionId);
 }
 
@@ -1166,6 +1175,9 @@ function cleanupAllSessions() {
       // Ignore cleanup errors
     }
   }
+  for (const [sessionId] of sessions) {
+    ptyProcessTree.unregisterPid(sessionId);
+  }
   sessions.clear();
 }
 

electron/bridges/vaultBackupBridge.cjs

@@ -97,6 +97,7 @@ function toBackupSummary(record) {
     id: record.id,
     createdAt: record.createdAt,
     reason: record.reason,
+    syncDataVersion: record.syncDataVersion,
     sourceAppVersion: record.sourceAppVersion,
     targetAppVersion: record.targetAppVersion,
     preview: record.preview,
@@ -131,6 +132,15 @@ function sanitizeOptionalVersionString(value) {
   return trimmed;
 }
 
+// Sync data version is the integer that the CloudSyncManager increments
+// on each successful cloud sync. Reject anything non-finite, non-positive,
+// or non-integer so the persisted record only carries meaningful values.
+function sanitizeOptionalSyncDataVersion(value) {
+  if (typeof value !== "number" || !Number.isFinite(value)) return undefined;
+  if (value < 1) return undefined;
+  return Math.floor(value);
+}
+
 // UTF-8 byte length of a payload's JSON serialization. Earlier revisions
 // returned `JSON.stringify(payload).length` (UTF-16 code units), which
 // under-counted by ~3x for non-ASCII vaults — a deck full of CJK snippet
@@ -415,6 +425,7 @@ function createVaultBackupService({ app, safeStorage, shell }) {
       id,
       createdAt,
       reason: sanitizeReason(options.reason),
+      syncDataVersion: sanitizeOptionalSyncDataVersion(options.syncDataVersion),
       sourceAppVersion: sanitizeOptionalVersionString(options.sourceAppVersion),
       targetAppVersion: sanitizeOptionalVersionString(options.targetAppVersion),
       fingerprint,

electron/bridges/vaultBackupBridge.test.cjs

@@ -417,6 +417,70 @@ test("createBackup accepts a legitimate SemVer-ish version string", async () =>
   }
 });
 
+test("createBackup persists syncDataVersion when given a positive integer", async () => {
+  const rootDir = createTempRoot();
+  const service = createService(rootDir);
+
+  try {
+    const result = await service.createBackup({
+      payload: samplePayload(),
+      reason: "before_restore",
+      syncDataVersion: 5,
+    });
+    assert.equal(result.created, true);
+    assert.equal(result.backup.syncDataVersion, 5);
+
+    // Round-trip via list
+    const listed = await service.listBackups();
+    assert.equal(listed[0].syncDataVersion, 5);
+  } finally {
+    fs.rmSync(rootDir, { recursive: true, force: true });
+  }
+});
+
+test("createBackup drops invalid syncDataVersion values (zero, negative, non-finite, non-numeric)", async () => {
+  const rootDir = createTempRoot();
+  const service = createService(rootDir);
+
+  try {
+    const cases = [0, -1, NaN, Infinity, "5", null, undefined];
+    let idx = 0;
+    for (const syncDataVersion of cases) {
+      // Vary an actual content-bearing field to avoid fingerprint dedupe
+      // (top-level syncedAt is normalized away in the fingerprint).
+      const payload = samplePayload({
+        hosts: [{ ...samplePayload().hosts[0], id: `h-case-${idx}` }],
+      });
+      const result = await service.createBackup({
+        payload,
+        reason: "before_restore",
+        syncDataVersion,
+      });
+      assert.equal(result.created, true, `iteration ${idx}: created should be true`);
+      assert.equal(result.backup.syncDataVersion, undefined, `value ${String(syncDataVersion)} should be dropped`);
+      idx += 1;
+    }
+  } finally {
+    fs.rmSync(rootDir, { recursive: true, force: true });
+  }
+});
+
+test("createBackup floors a fractional syncDataVersion", async () => {
+  const rootDir = createTempRoot();
+  const service = createService(rootDir);
+
+  try {
+    const result = await service.createBackup({
+      payload: samplePayload(),
+      reason: "before_restore",
+      syncDataVersion: 7.9,
+    });
+    assert.equal(result.backup.syncDataVersion, 7);
+  } finally {
+    fs.rmSync(rootDir, { recursive: true, force: true });
+  }
+});
+
 test("createBackup rejects an array payload (not an object)", async () => {
   const rootDir = createTempRoot();
   const service = createService(rootDir);

electron/main.cjs

@@ -165,6 +165,7 @@ const getAutoUpdateBridge = createLazyModule("./bridges/autoUpdateBridge.cjs");
 const getAiBridge = createLazyModule("./bridges/aiBridge.cjs");
 const getWindowManager = createLazyModule("./bridges/windowManager.cjs");
 const getVaultBackupBridge = createLazyModule("./bridges/vaultBackupBridge.cjs");
+const ptyProcessTree = require("./bridges/ptyProcessTree.cjs");
 
 // GPU settings
 // NOTE: Do not disable Chromium sandbox by default.
@@ -683,6 +684,40 @@ const registerBridges = (win) => {
     };
   });
 
+  // PTY child process list for busy-check before close
+  ipcMain.handle("netcatty:pty:childProcesses", async (_event, sessionId) => {
+    if (typeof sessionId !== "string") return [];
+    return ptyProcessTree.getChildProcesses(sessionId);
+  });
+
+  // Native confirmation dialog when closing a session with a running process
+  // Returns true only if the user explicitly clicks "Close". ESC/dialog-dismiss
+  // resolves as cancelId (0) → false, which is the safe default (do not close).
+  ipcMain.handle(
+    "netcatty:dialog:confirmCloseBusy",
+    async (event, payload) => {
+      const command = typeof payload?.command === "string" ? payload.command : "unknown";
+      const title = typeof payload?.title === "string" ? payload.title : "Confirm close";
+      const message = typeof payload?.message === "string"
+        ? payload.message
+        : `Process "${command}" is still running and will be terminated.`;
+      const cancelLabel = typeof payload?.cancelLabel === "string" ? payload.cancelLabel : "Cancel";
+      const closeLabel = typeof payload?.closeLabel === "string" ? payload.closeLabel : "Close";
+      const { dialog } = electronModule;
+      const win = BrowserWindow.fromWebContents(event.sender);
+      const { response } = await dialog.showMessageBox(win || undefined, {
+        type: "warning",
+        title,
+        message,
+        buttons: [cancelLabel, closeLabel],
+        defaultId: 0,
+        cancelId: 0,
+        noLink: true,
+      });
+      return response === 1; // true = user picked Close
+    },
+  );
+
   // Clipboard helpers for renderer fallback paths (e.g. Monaco paste in Electron)
   ipcMain.handle("netcatty:clipboard:readText", async () => {
     try {

electron/preload.cjs

@@ -858,6 +858,10 @@ const api = {
 
   // App info
   getAppInfo: () => ipcRenderer.invoke("netcatty:app:getInfo"),
+  ptyGetChildProcesses: (sessionId) =>
+    ipcRenderer.invoke("netcatty:pty:childProcesses", sessionId),
+  confirmCloseBusy: (payload) =>
+    ipcRenderer.invoke("netcatty:dialog:confirmCloseBusy", payload),
   getVaultBackupCapabilities: () =>
     ipcRenderer.invoke("netcatty:vaultBackups:capabilities"),
   createVaultBackup: (payload) =>

global.d.ts

@@ -512,6 +512,14 @@ declare global {
 
     // App info (name/version/platform) for About screens
     getAppInfo?(): Promise<{ name: string; version: string; platform: string }>;
+    ptyGetChildProcesses?(sessionId: string): Promise<Array<{ pid: number; command: string }>>;
+    confirmCloseBusy?(payload: {
+      command: string;
+      title?: string;
+      message?: string;
+      cancelLabel?: string;
+      closeLabel?: string;
+    }): Promise<boolean>;
     getVaultBackupCapabilities?(): Promise<{ encryptionAvailable: boolean }>;
     createVaultBackup?(payload: {
       payload: import('./domain/sync').SyncPayload;

infrastructure/services/CloudSyncManager.ts

@@ -45,6 +45,7 @@ import {
   encryptProviderSecrets,
 } from '../persistence/secureFieldAdapter';
 import { mergeSyncPayloads } from '../../domain/syncMerge';
+import { detectSuspiciousShrink, type ShrinkFinding } from '../../domain/syncGuards';
 // Extracted into a plain ESM module so the signature logic is covered by
 // the node --test harness (see syncSignature.test.mjs). The previous
 // inline implementation only hashed a handful of meta fields and was
@@ -77,6 +78,12 @@ export interface SyncManagerState {
   autoSyncEnabled: boolean;
   autoSyncInterval: number;
   syncHistory: SyncHistoryEntry[];
+  /** Last shrink finding that put us into BLOCKED state, retained until
+   * a sync actually succeeds (SYNC_COMPLETED with result.success) or
+   * `clearShrinkBlockedState()` is called. Renderer hydrates the banner
+   * from this on mount so a block that happened off-screen is still
+   * visible to the user. */
+  lastShrinkFinding?: Extract<ShrinkFinding, { suspicious: true }>;
 }
 
 export type SyncEventCallback = (event: SyncEvent) => void;
@@ -752,6 +759,12 @@ export class CloudSyncManager {
     const ghAdapter = adapter as GitHubAdapter;
 
     try {
+      // Snapshot the prior account BEFORE we overwrite providers[provider].
+      // Used as a fallback for the same-account comparison when the persisted
+      // accountId key is absent (e.g., first re-auth after upgrading to this
+      // version, where the key didn't exist yet).
+      const previousAccount = this.state.providers.github?.account;
+
       const tokens = await ghAdapter.completeAuth(deviceCode, interval, expiresAt, onPending);
 
       ++this.providerDecryptSeq.github;
@@ -769,9 +782,20 @@ export class CloudSyncManager {
       }
 
       await this.saveProviderConnection('github', this.state.providers.github);
-      // Clear merge base when (re)authenticating to a potentially different account
-      this.removeFromStorage(this.syncBaseKey('github'));
-      this.clearSyncAnchor('github');
+
+      // Only clear the merge base if the authenticated account identity differs
+      // from the previously-stored one. See notes in completePKCEAuth.
+      const newId = ghAdapter.accountInfo?.id ?? null;
+      const previousId = this.loadProviderAccountId('github') ?? previousAccount?.id ?? null;
+      const sameAccount = newId !== null && previousId !== null && newId === previousId;
+      if (!sameAccount) {
+        this.removeFromStorage(this.syncBaseKey('github'));
+        this.clearSyncAnchor('github');
+      }
+      if (newId) {
+        this.saveProviderAccountId('github', newId);
+      }
+
       this.emit({
         type: 'AUTH_COMPLETED',
         provider: 'github',
@@ -797,6 +821,12 @@ export class CloudSyncManager {
     }
 
     try {
+      // Snapshot the prior account BEFORE we overwrite providers[provider].
+      // Used as a fallback for the same-account comparison when the persisted
+      // accountId key is absent (e.g., first re-auth after upgrading to this
+      // version, where the key didn't exist yet).
+      const previousAccount = this.state.providers[provider]?.account;
+
       let tokens: OAuthTokens;
       let account;
 
@@ -825,9 +855,22 @@ export class CloudSyncManager {
       }
 
       await this.saveProviderConnection(provider, this.state.providers[provider]);
-      // Clear merge base when (re)authenticating to a potentially different account
-      this.removeFromStorage(this.syncBaseKey(provider));
-      this.clearSyncAnchor(provider);
+
+      // Only clear the merge base if the authenticated account identity differs
+      // from the previously-stored one. Same-account re-auth preserves the base
+      // so the next sync computes correct local-deletions instead of treating
+      // it as "first sync" and resurrecting zombie entries via null-base union.
+      const newId = account?.id ?? null;
+      const previousId = this.loadProviderAccountId(provider) ?? previousAccount?.id ?? null;
+      const sameAccount = newId !== null && previousId !== null && newId === previousId;
+      if (!sameAccount) {
+        this.removeFromStorage(this.syncBaseKey(provider));
+        this.clearSyncAnchor(provider);
+      }
+      if (newId) {
+        this.saveProviderAccountId(provider, newId);
+      }
+
       this.emit({
         type: 'AUTH_COMPLETED',
         provider,
@@ -912,6 +955,13 @@ export class CloudSyncManager {
     // account/resource doesn't reuse an unrelated snapshot
     this.removeFromStorage(this.syncBaseKey(provider));
     this.clearSyncAnchor(provider);
+    this.removeFromStorage(this.providerAccountIdKey(provider));
+    // Reset BLOCKED state if it was present — disconnect implicitly resolves
+    // any pending shrink-block warning since there's no provider to push to.
+    this.exitBlockedState();
+    if (this.state.syncState === 'BLOCKED') {
+      this.state.syncState = 'IDLE';
+    }
     this.notifyStateChange(); // Ensure UI updates immediately after disconnect
   }
 
@@ -1227,7 +1277,8 @@ export class CloudSyncManager {
    */
   async syncToProvider(
     provider: CloudProvider,
-    payload: SyncPayload
+    payload: SyncPayload,
+    opts: { overrideShrink?: boolean } = {},
   ): Promise<SyncResult> {
     if (this.state.securityState !== 'UNLOCKED') {
       return {
@@ -1247,6 +1298,8 @@ export class CloudSyncManager {
       };
     }
 
+    const overrideShrinkRequested = opts.overrideShrink === true;
+
     let adapter: CloudAdapter;
     try {
       adapter = await this.getConnectedAdapter(provider);
@@ -1288,6 +1341,30 @@ export class CloudSyncManager {
 
           console.info('[CloudSyncManager] Three-way merge completed', mergeResult.summary);
 
+          // Shrink guard: refuse to push a merged payload that silently deletes
+          // entities we still have in base. The merge itself is correct if local
+          // state is trustworthy — but a degraded local (keychain failure,
+          // partial load) can make merge produce a smaller-than-expected result.
+          const mergedShrink = detectSuspiciousShrink(mergeResult.payload, base);
+          const shouldBlockMerged = mergedShrink.suspicious && !overrideShrinkRequested;
+          const shouldForceMerged = mergedShrink.suspicious && overrideShrinkRequested;
+          if (shouldBlockMerged) {
+            this.state.syncState = 'BLOCKED';
+            this.state.lastShrinkFinding = mergedShrink;
+            this.emit({ type: 'SYNC_BLOCKED_SHRINK', provider, finding: mergedShrink });
+            this.updateProviderStatus(provider, 'error', 'Sync blocked: would delete too much');
+            return {
+              success: false,
+              provider,
+              action: 'none',
+              shrinkBlocked: true,
+              finding: mergedShrink,
+            };
+          }
+          if (shouldForceMerged) {
+            this.emit({ type: 'SYNC_FORCED', provider, finding: mergedShrink });
+          }
+
           // Encrypt and upload merged payload
           const mergedSyncedFile = await EncryptionService.encryptPayload(
             mergeResult.payload,
@@ -1309,6 +1386,7 @@ export class CloudSyncManager {
             // Base was persisted inside uploadToProvider before the
             // anchor advanced, so a crash between them cannot leave a
             // stale base pointing at pre-merge state.
+            this.exitBlockedState();
             this.state.syncState = 'IDLE';
 
             this.addSyncHistoryEntry({
@@ -1361,6 +1439,29 @@ export class CloudSyncManager {
         }
       }
 
+      // Shrink guard (no-conflict path): same rationale as the merge branch —
+      // refuse a payload that drops entities versus the stored base.
+      const directBase = await this.loadSyncBase(provider);
+      const directShrink = detectSuspiciousShrink(payload, directBase);
+      const shouldBlockDirect = directShrink.suspicious && !overrideShrinkRequested;
+      const shouldForceDirect = directShrink.suspicious && overrideShrinkRequested;
+      if (shouldBlockDirect) {
+        this.state.syncState = 'BLOCKED';
+        this.state.lastShrinkFinding = directShrink;
+        this.emit({ type: 'SYNC_BLOCKED_SHRINK', provider, finding: directShrink });
+        this.updateProviderStatus(provider, 'error', 'Sync blocked: would delete too much');
+        return {
+          success: false,
+          provider,
+          action: 'none',
+          shrinkBlocked: true,
+          finding: directShrink,
+        };
+      }
+      if (shouldForceDirect) {
+        this.emit({ type: 'SYNC_FORCED', provider, finding: directShrink });
+      }
+
       // 2. Encrypt
       const syncedFile = await EncryptionService.encryptPayload(
         payload,
@@ -1377,7 +1478,9 @@ export class CloudSyncManager {
       const result = await this.uploadToProvider(provider, adapter, syncedFile, payload);
 
       if (result.success) {
+        this.exitBlockedState();
         this.state.syncState = 'IDLE';
+        this.state.lastShrinkFinding = undefined;
       } else {
         this.state.syncState = 'ERROR';
         if (result.error) {
@@ -1550,26 +1653,73 @@ export class CloudSyncManager {
       // Download and return remote data
       const payload = await this.downloadFromProvider(provider);
       this.state.currentConflict = null;
+      this.exitBlockedState();
       this.state.syncState = 'IDLE';
       this.notifyStateChange(); // Notify UI of conflict resolution
       return payload;
     } else {
       // USE_LOCAL - just clear conflict, caller will re-sync
       this.state.currentConflict = null;
+      this.exitBlockedState();
       this.state.syncState = 'IDLE';
       this.notifyStateChange(); // Notify UI of conflict resolution
       return null;
     }
   }
 
+  /**
+   * Side-effect helper: called BEFORE any syncState assignment that transitions
+   * away from BLOCKED. Clears lastShrinkFinding and emits SYNC_BLOCKED_CLEARED
+   * so the UI banner (and any other subscriber) gets a single, authoritative
+   * "block resolved" signal. The guard on syncState === 'BLOCKED' makes it safe
+   * to call unconditionally at every non-BLOCKED assignment site — it no-ops
+   * when the state was already non-BLOCKED.
+   */
+  private exitBlockedState(): void {
+    if (this.state.syncState === 'BLOCKED') {
+      this.state.lastShrinkFinding = undefined;
+      this.emit({ type: 'SYNC_BLOCKED_CLEARED' });
+    }
+  }
+
+  /**
+   * Reset BLOCKED back to IDLE without going through a successful sync.
+   * Used by post-merge round-trip to avoid wedging the manager in BLOCKED
+   * when the merge already produced safe local state and the round-trip
+   * push is just an optimization.
+   */
+  clearShrinkBlockedState(): void {
+    if (this.state.syncState === 'BLOCKED') {
+      this.exitBlockedState();
+      this.state.syncState = 'IDLE';
+      this.notifyStateChange();
+    }
+  }
+
+  /**
+   * Returns the last shrink finding that triggered BLOCKED state, or
+   * null if not currently blocked. Used by the renderer to hydrate the
+   * SyncBlockedBanner when opening Settings after a block happened
+   * off-screen.
+   */
+  getShrinkBlockedFinding(): Extract<ShrinkFinding, { suspicious: true }> | null {
+    if (this.state.syncState !== 'BLOCKED') return null;
+    return this.state.lastShrinkFinding ?? null;
+  }
+
   /**
    * Sync to all connected providers
    */
-  async syncAllProviders(inputPayload?: SyncPayload): Promise<Map<CloudProvider, SyncResult>> {
+  async syncAllProviders(
+    inputPayload?: SyncPayload,
+    opts: { overrideShrink?: boolean } = {},
+  ): Promise<Map<CloudProvider, SyncResult>> {
     const results = new Map<CloudProvider, SyncResult>();
     let payload = inputPayload;
     let wasMerged = false;
 
+    const overrideShrinkRequested = opts.overrideShrink === true;
+
     if (!payload) {
       // Caller should provide payload from app state
       return results;
@@ -1743,6 +1893,80 @@ export class CloudSyncManager {
       }
     }
 
+    // Shrink guard (multi-provider): check the final outgoing payload against
+    // each provider's stored base. If ANY provider would suffer a suspicious
+    // shrink, block ALL uploads — the same payload goes to every provider, so
+    // any one provider's "would lose too much" is a global block. Override flag
+    // is one-shot and clears regardless of outcome.
+    const shrinkSuspectByProvider: Array<{
+      provider: CloudProvider;
+      finding: Extract<ShrinkFinding, { suspicious: true }>;
+    }> = [];
+    const candidateProviders = checkResults
+      .filter((r) => !r.error && !r.check?.conflict && r.adapter)
+      .map((r) => r.provider as CloudProvider);
+    for (const provider of candidateProviders) {
+      const providerBase = await this.loadSyncBase(provider);
+      const finding = detectSuspiciousShrink(payload, providerBase);
+      if (finding.suspicious) {
+        shrinkSuspectByProvider.push({ provider, finding });
+      }
+    }
+    const shouldBlockAll = shrinkSuspectByProvider.length > 0 && !overrideShrinkRequested;
+    const shouldForceAll = shrinkSuspectByProvider.length > 0 && overrideShrinkRequested;
+
+    if (shouldBlockAll) {
+      this.state.syncState = 'BLOCKED';
+      this.state.lastShrinkFinding = shrinkSuspectByProvider[0].finding;
+      for (const { provider, finding } of shrinkSuspectByProvider) {
+        this.emit({ type: 'SYNC_BLOCKED_SHRINK', provider, finding });
+        this.updateProviderStatus(provider, 'error', 'Sync blocked: would delete too much');
+        results.set(provider, {
+          success: false,
+          provider,
+          action: 'none',
+          shrinkBlocked: true,
+          finding,
+        });
+      }
+      // Process check errors from the parallel check phase so a provider that
+      // failed during checkProviderConflict is not silently dropped from results.
+      checkResults.forEach((r) => {
+        if (r.error) {
+          results.set(r.provider as CloudProvider, {
+            success: false,
+            provider: r.provider as CloudProvider,
+            action: 'none',
+            error: r.error,
+          });
+          this.updateProviderStatus(r.provider as CloudProvider, 'error', r.error);
+          this.emit({ type: 'SYNC_ERROR', provider: r.provider as CloudProvider, error: r.error });
+        }
+      });
+      // Providers in candidateProviders that didn't trip the shrink check still
+      // share the same payload — mark them as not-uploaded so the caller doesn't
+      // think a "successful" no-op happened.
+      const blockedProviders = new Set(shrinkSuspectByProvider.map((e) => e.provider));
+      for (const provider of candidateProviders) {
+        if (!results.has(provider) && !blockedProviders.has(provider)) {
+          results.set(provider, {
+            success: false,
+            provider,
+            action: 'none',
+            error: 'Sync blocked: another provider would lose too much data',
+          });
+          this.updateProviderStatus(provider, 'error', 'Sync blocked due to peer provider');
+        }
+      }
+      return results;
+    }
+
+    if (shouldForceAll) {
+      for (const { provider, finding } of shrinkSuspectByProvider) {
+        this.emit({ type: 'SYNC_FORCED', provider, finding });
+      }
+    }
+
     // 3. Encrypt Once
     const validUploads = checkResults.filter(
       (r) => !r.error && !r.check?.conflict && r.adapter
@@ -1819,7 +2043,9 @@ export class CloudSyncManager {
     // 5. Final State Update
     const hasSuccess = Array.from(results.values()).some((r) => r.success);
     if (hasSuccess) {
+      this.exitBlockedState();
       this.state.syncState = 'IDLE';
+      this.state.lastShrinkFinding = undefined;
 
       // If a merge happened, attach the merged payload to successful results
       // so callers can apply remote additions to local state
@@ -1922,6 +2148,18 @@ export class CloudSyncManager {
     return `${SYNC_STORAGE_KEYS.SYNC_BASE_PAYLOAD}${suffix}`;
   }
 
+  private providerAccountIdKey(provider: CloudProvider): string {
+    return `netcatty.sync.accountId.${provider}`;
+  }
+
+  private loadProviderAccountId(provider: CloudProvider): string | null {
+    return this.loadFromStorage<string>(this.providerAccountIdKey(provider)) ?? null;
+  }
+
+  private saveProviderAccountId(provider: CloudProvider, id: string): void {
+    this.saveToStorage(this.providerAccountIdKey(provider), id);
+  }
+
   async saveSyncBase(payload: SyncPayload, provider?: CloudProvider): Promise<void> {
     const key = this.state.unlockedKey?.derivedKey;
     if (!key) return;

package-lock.json

@@ -81,9 +81,13 @@
         "eslint-plugin-unused-imports": "^4.3.0",
         "patch-package": "^8.0.0",
         "tailwindcss": "^4.1.17",
+        "tsx": "^4.21.0",
         "typescript": "~5.9.3",
         "vite": "^7.2.7",
         "wait-on": "^9.0.3"
+      },
+      "optionalDependencies": {
+        "@vscode/windows-process-tree": "^0.7.0"
       }
     },
     "node_modules/@agentclientprotocol/sdk": {
@@ -1154,6 +1158,7 @@
       "integrity": "sha512-CGOfOJqWjg2qW/Mb6zNsDm+u5vFQ8DxXfbM09z69p5Z6+mE1ikP2jUXw+j42Pf1XTYED2Rni5f95npYeuwMDQA==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@babel/code-frame": "^7.29.0",
         "@babel/generator": "^7.29.0",
@@ -1799,7 +1804,6 @@
       "dev": true,
       "license": "BSD-2-Clause",
       "optional": true,
-      "peer": true,
       "dependencies": {
         "cross-dirname": "^0.1.0",
         "debug": "^4.3.4",
@@ -1821,7 +1825,6 @@
       "dev": true,
       "license": "MIT",
       "optional": true,
-      "peer": true,
       "dependencies": {
         "graceful-fs": "^4.2.0",
         "jsonfile": "^6.0.1",
@@ -1838,7 +1841,6 @@
       "dev": true,
       "license": "MIT",
       "optional": true,
-      "peer": true,
       "dependencies": {
         "universalify": "^2.0.0"
       },
@@ -1853,7 +1855,6 @@
       "dev": true,
       "license": "MIT",
       "optional": true,
-      "peer": true,
       "engines": {
         "node": ">= 10.0.0"
       }
@@ -3309,6 +3310,7 @@
       "resolved": "https://registry.npmjs.org/@modelcontextprotocol/sdk/-/sdk-1.27.1.tgz",
       "integrity": "sha512-sr6GbP+4edBwFndLbM60gf07z0FQ79gaExpnsjMGePXqFcSSb7t6iscpjk9DhFhwd+mTEQrzNafGP8/iGGFYaA==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@hono/node-server": "^1.19.9",
         "ajv": "^8.17.1",
@@ -6297,6 +6299,7 @@
       "resolved": "https://registry.npmjs.org/@types/mdast/-/mdast-4.0.4.tgz",
       "integrity": "sha512-kGaNbPh1k7AFzgpud/gMdvIm5xuECykRR+JnWKQno9TAXVa6WIVCGTPvYGekIDL4uwCZQSYbUxNBSb1aUo79oA==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@types/unist": "*"
       }
@@ -6377,6 +6380,7 @@
       "integrity": "sha512-hAAP5io/7csFStuOmR782YmTthKBJ9ND3WVL60hcOjvtGFb+HJxH4O5huAcmcZ9v9G8P+JETiZ/G1B8MALnWZQ==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@eslint-community/regexpp": "^4.12.2",
         "@typescript-eslint/scope-manager": "8.54.0",
@@ -6406,6 +6410,7 @@
       "integrity": "sha512-BtE0k6cjwjLZoZixN0t5AKP0kSzlGu7FctRXYuPAm//aaiZhmfq1JwdYpYr1brzEspYyFeF+8XF5j2VK6oalrA==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@typescript-eslint/scope-manager": "8.54.0",
         "@typescript-eslint/types": "8.54.0",
@@ -6640,6 +6645,27 @@
         "vite": "^4.2.0 || ^5.0.0 || ^6.0.0 || ^7.0.0"
       }
     },
+    "node_modules/@vscode/windows-process-tree": {
+      "version": "0.7.0",
+      "resolved": "https://registry.npmjs.org/@vscode/windows-process-tree/-/windows-process-tree-0.7.0.tgz",
+      "integrity": "sha512-uH58Fofu1bgiulsY2svyGOLLKAYNJ0Req4PioPd7BZzHRziuiBRw1SxyT7wvsYHvm7eKWwzwo6mZpExDfwX9iA==",
+      "hasInstallScript": true,
+      "license": "MIT",
+      "optional": true,
+      "dependencies": {
+        "node-addon-api": "7.1.0"
+      }
+    },
+    "node_modules/@vscode/windows-process-tree/node_modules/node-addon-api": {
+      "version": "7.1.0",
+      "resolved": "https://registry.npmjs.org/node-addon-api/-/node-addon-api-7.1.0.tgz",
+      "integrity": "sha512-mNcltoe1R8o7STTegSOHdnJNN7s5EUvhoS7ShnTHDyOSd+8H+UdWODq6qSv67PjC8Zc5JRT8+oLAMCr0SIXw7g==",
+      "license": "MIT",
+      "optional": true,
+      "engines": {
+        "node": "^16 || ^18 || >= 20"
+      }
+    },
     "node_modules/@withfig/autocomplete": {
       "version": "2.692.3",
       "resolved": "https://registry.npmjs.org/@withfig/autocomplete/-/autocomplete-2.692.3.tgz",
@@ -6935,6 +6961,7 @@
       "integrity": "sha512-NZyJarBfL7nWwIq+FDL6Zp/yHEhePMNnnJ0y3qfieCrmNvYct8uvtiV41UvlSe6apAfk0fY1FbWx+NwfmpvtTg==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "bin": {
         "acorn": "bin/acorn"
       },
@@ -6985,6 +7012,7 @@
       "integrity": "sha512-j3fVLgvTo527anyYyJOGTYJbG+vnnQYvE0m5mmkc1TK+nxAppkCLMIL0aZ4dblVCNoGShhm+kzE4ZUykBoMg4g==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "fast-deep-equal": "^3.1.1",
         "fast-json-stable-stringify": "^2.0.0",
@@ -7545,6 +7573,7 @@
         }
       ],
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "baseline-browser-mapping": "^2.9.0",
         "caniuse-lite": "^1.0.30001759",
@@ -8287,8 +8316,7 @@
       "integrity": "sha512-+R08/oI0nl3vfPcqftZRpytksBXDzOUveBq/NBVx0sUp1axwzPQrKinNx5yd5sxPu8j1wIy8AfnVQ+5eFdha6Q==",
       "dev": true,
       "license": "MIT",
-      "optional": true,
-      "peer": true
+      "optional": true
     },
     "node_modules/cross-env": {
       "version": "10.1.0",
@@ -8572,6 +8600,7 @@
       "integrity": "sha512-uOOBA3f+kW3o4KpSoMQ6SNpdXU7WtxlJRb9vCZgOvqhTz4b3GjcoWKstdisizNZLsylhTMv8TLHFPFW0Uxsj/g==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "app-builder-lib": "26.7.0",
         "builder-util": "26.4.1",
@@ -8953,7 +8982,6 @@
       "dev": true,
       "hasInstallScript": true,
       "license": "MIT",
-      "peer": true,
       "dependencies": {
         "@electron/asar": "^3.2.1",
         "debug": "^4.1.1",
@@ -8974,7 +9002,6 @@
       "integrity": "sha512-YJDaCJZEnBmcbw13fvdAM9AwNOJwOzrE4pqMqBq5nFiEqXUqHwlK4B+3pUw6JNvfSPtX05xFHtYy/1ni01eGCw==",
       "dev": true,
       "license": "MIT",
-      "peer": true,
       "dependencies": {
         "graceful-fs": "^4.1.2",
         "jsonfile": "^4.0.0",
@@ -9204,6 +9231,7 @@
       "integrity": "sha512-LEyamqS7W5HB3ujJyvi0HQK/dtVINZvd5mAAp9eT5S/ujByGjiZLCzPcHVzuXbpJDJF/cxwHlfceVUDZ2lnSTw==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@eslint-community/eslint-utils": "^4.8.0",
         "@eslint-community/regexpp": "^4.12.1",
@@ -10102,6 +10130,19 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
+    "node_modules/get-tsconfig": {
+      "version": "4.14.0",
+      "resolved": "https://registry.npmjs.org/get-tsconfig/-/get-tsconfig-4.14.0.tgz",
+      "integrity": "sha512-yTb+8DXzDREzgvYmh6s9vHsSVCHeC0G3PI5bEXNBHtmshPnO+S5O7qgLEOn0I5QvMy6kpZN8K1NKGyilLb93wA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "resolve-pkg-maps": "^1.0.0"
+      },
+      "funding": {
+        "url": "https://github.com/privatenumber/get-tsconfig?sponsor=1"
+      }
+    },
     "node_modules/glob": {
       "version": "7.2.3",
       "resolved": "https://registry.npmjs.org/glob/-/glob-7.2.3.tgz",
@@ -10552,6 +10593,7 @@
       "resolved": "https://registry.npmjs.org/hono/-/hono-4.12.7.tgz",
       "integrity": "sha512-jq9l1DM0zVIvsm3lv9Nw9nlJnMNPOcAtsbsgiUhWcFzPE99Gvo6yRTlszSLLYacMeQ6quHD6hMfId8crVHvexw==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=16.9.0"
       }
@@ -12041,6 +12083,7 @@
         }
       ],
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@types/debug": "^4.0.0",
         "debug": "^4.0.0",
@@ -12658,7 +12701,8 @@
           "url": "https://opencollective.com/unified"
         }
       ],
-      "license": "MIT"
+      "license": "MIT",
+      "peer": true
     },
     "node_modules/micromatch": {
       "version": "4.0.8",
@@ -12913,7 +12957,6 @@
       "integrity": "sha512-FP+p8RB8OWpF3YZBCrP5gtADmtXApB5AMLn+vdyA+PyxCjrCs00mjyUozssO33cwDeT3wNGdLxJ5M//YqtHAJw==",
       "dev": true,
       "license": "MIT",
-      "peer": true,
       "dependencies": {
         "minimist": "^1.2.6"
       },
@@ -12926,6 +12969,7 @@
       "resolved": "https://registry.npmjs.org/monaco-editor/-/monaco-editor-0.55.1.tgz",
       "integrity": "sha512-jz4x+TJNFHwHtwuV9vA9rMujcZRb0CEilTEwG2rRSpe/A7Jdkuj8xPKttCgOh+v/lkHy7HsZ64oj+q3xoAFl9A==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "dompurify": "3.2.7",
         "marked": "14.0.0"
@@ -13685,7 +13729,6 @@
       "dev": true,
       "license": "MIT",
       "optional": true,
-      "peer": true,
       "dependencies": {
         "commander": "^9.4.0"
       },
@@ -13703,7 +13746,6 @@
       "dev": true,
       "license": "MIT",
       "optional": true,
-      "peer": true,
       "engines": {
         "node": "^12.20.0 || >=14"
       }
@@ -13894,6 +13936,7 @@
       "resolved": "https://registry.npmjs.org/react/-/react-19.2.4.tgz",
       "integrity": "sha512-9nfp2hYpCwOjAN+8TZFGhtWEwgvWHXqESH8qT89AT/lWklpLON22Lc8pEtnpsZz7VmawabSU0gCjnj8aC0euHQ==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=0.10.0"
       }
@@ -13903,6 +13946,7 @@
       "resolved": "https://registry.npmjs.org/react-dom/-/react-dom-19.2.4.tgz",
       "integrity": "sha512-AXJdLo8kgMbimY95O2aKQqsz2iWi9jMgKJhRBAxECE4IFxfcazB2LmzloIoibJI3C12IlY20+KFaLv+71bUJeQ==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "scheduler": "^0.27.0"
       },
@@ -14252,6 +14296,16 @@
         "node": ">=4"
       }
     },
+    "node_modules/resolve-pkg-maps": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/resolve-pkg-maps/-/resolve-pkg-maps-1.0.0.tgz",
+      "integrity": "sha512-seS2Tj26TBVOC2NIc2rOe2y2ZO7efxITtLZcGSOnHHNOQ7CkiUBfw0Iw2ck6xkIhPwLhKNLS8BO+hEpngQlqzw==",
+      "dev": true,
+      "license": "MIT",
+      "funding": {
+        "url": "https://github.com/privatenumber/resolve-pkg-maps?sponsor=1"
+      }
+    },
     "node_modules/responselike": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/responselike/-/responselike-2.0.1.tgz",
@@ -15223,7 +15277,6 @@
       "integrity": "sha512-yYrrsWnrXMcdsnu/7YMYAofM1ktpL5By7vZhf15CrXijWWrEYZks5AXBudalfSWJLlnen/QUJUB5aoB0kqZUGA==",
       "dev": true,
       "license": "MIT",
-      "peer": true,
       "dependencies": {
         "mkdirp": "^0.5.1",
         "rimraf": "~2.6.2"
@@ -15288,7 +15341,6 @@
       "deprecated": "Rimraf versions prior to v4 are no longer supported",
       "dev": true,
       "license": "ISC",
-      "peer": true,
       "dependencies": {
         "glob": "^7.1.3"
       },
@@ -15363,6 +15415,7 @@
       "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=12"
       },
@@ -15471,6 +15524,27 @@
       "integrity": "sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==",
       "license": "0BSD"
     },
+    "node_modules/tsx": {
+      "version": "4.21.0",
+      "resolved": "https://registry.npmjs.org/tsx/-/tsx-4.21.0.tgz",
+      "integrity": "sha512-5C1sg4USs1lfG0GFb2RLXsdpXqBSEhAaA/0kPL01wxzpMqLILNxIxIOKiILz+cdg/pLnOUxFYOR5yhHU666wbw==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "esbuild": "~0.27.0",
+        "get-tsconfig": "^4.7.5"
+      },
+      "bin": {
+        "tsx": "dist/cli.mjs"
+      },
+      "engines": {
+        "node": ">=18.0.0"
+      },
+      "optionalDependencies": {
+        "fsevents": "~2.3.3"
+      }
+    },
     "node_modules/tweetnacl": {
       "version": "0.14.5",
       "resolved": "https://registry.npmjs.org/tweetnacl/-/tweetnacl-0.14.5.tgz",
@@ -15555,6 +15629,7 @@
       "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
       "dev": true,
       "license": "Apache-2.0",
+      "peer": true,
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
@@ -15575,6 +15650,7 @@
       "resolved": "https://registry.npmjs.org/unified/-/unified-11.0.5.tgz",
       "integrity": "sha512-xKvGhPWw3k84Qjh8bI3ZeJjqnyadK+GEFtazSfZv/rKeTkTjOJho6mFqh2SM96iIcZokxiOpg78GazTSg8+KHA==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@types/unist": "^3.0.0",
         "bail": "^2.0.0",
@@ -15913,6 +15989,7 @@
       "integrity": "sha512-w+N7Hifpc3gRjZ63vYBXA56dvvRlNWRczTdmCBBa+CotUzAPf5b7YMdMR/8CQoeYE5LX3W4wj6RYTgonm1b9DA==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "esbuild": "^0.27.0",
         "fdir": "^6.5.0",
@@ -16006,6 +16083,7 @@
       "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=12"
       },
@@ -16284,6 +16362,7 @@
       "resolved": "https://registry.npmjs.org/zod/-/zod-4.3.6.tgz",
       "integrity": "sha512-rftlrkhHZOcjDwkGlnUtZZkvaPHCsDATp4pGpuOOMDaTdDDXF91wuVDJoWoPsKX/3YPQ5fHuF3STjcYyKr+Qhg==",
       "license": "MIT",
+      "peer": true,
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"
       }

package.json

@@ -29,7 +29,8 @@
     "rebuild": "electron-builder install-app-deps",
     "tool:cli": "node electron/cli/netcatty-tool-cli.cjs",
     "lint": "eslint .",
-    "lint:fix": "eslint . --fix"
+    "lint:fix": "eslint . --fix",
+    "test": "node --test --import tsx electron/bridges/*.test.cjs application/state/*.test.ts domain/*.test.ts"
   },
   "dependencies": {
     "@ai-sdk/anthropic": "^3.0.58",
@@ -100,10 +101,14 @@
     "eslint-plugin-unused-imports": "^4.3.0",
     "patch-package": "^8.0.0",
     "tailwindcss": "^4.1.17",
+    "tsx": "^4.21.0",
     "typescript": "~5.9.3",
     "vite": "^7.2.7",
     "wait-on": "^9.0.3"
   },
+  "optionalDependencies": {
+    "@vscode/windows-process-tree": "^0.7.0"
+  },
   "overrides": {
     "cpu-features": "npm:empty-npm-package@1.0.0",
     "axios": "1.13.5"

patches/ssh2+1.17.0.patch

@@ -33,7 +33,7 @@ index 7291c2c..8943c9a 100644
  }
  
 diff --git a/node_modules/ssh2/lib/protocol/Protocol.js b/node_modules/ssh2/lib/protocol/Protocol.js
-index 7302488..95584c5 100644
+index 7302488..634acdd 100644
 --- a/node_modules/ssh2/lib/protocol/Protocol.js
 +++ b/node_modules/ssh2/lib/protocol/Protocol.js
 @@ -701,11 +701,19 @@ class Protocol {
@@ -107,6 +107,18 @@ index 7302488..95584c5 100644
        packet.set(signature, p += 4);
  
        this._authsQueue.push('hostbased');
+@@ -1916,7 +1932,10 @@ class Protocol {
+ }
+ 
+ // SSH-protoversion-softwareversion (SP comments) CR LF
+-const RE_IDENT = /^SSH-(2\.0|1\.99)-([^ ]+)(?: (.*))?$/;
++// RFC 4253 requires a non-empty softwareversion, but some embedded SSH
++// daemons send "SSH-2.0-" with an empty token. Accept that specific
++// compatibility case while still rejecting whitespace in the token itself.
++const RE_IDENT = /^SSH-(2\.0|1\.99)-([^ ]*)(?: (.*))?$/;
+ 
+ // TODO: optimize this by starting n bytes from the end of this._buffer instead
+ // of the beginning
 diff --git a/node_modules/ssh2/lib/protocol/SFTP.js b/node_modules/ssh2/lib/protocol/SFTP.js
 index 9f33c02..9751164 100644
 --- a/node_modules/ssh2/lib/protocol/SFTP.js

skills/netcatty-tool-cli/SKILL.md

@@ -25,12 +25,19 @@ For routine tasks, the host prompt is usually enough. Read only the reference th
 ## Core Rules
 
 - Treat the host-provided CLI prefix as the only supported entrypoint for this session.
+- If a command launcher is needed, prefer the operating system's built-in launcher for the current environment; do not require optional shells that may not be installed.
 - Run Netcatty CLI commands strictly serially.
 - Treat Netcatty CLI errors as authoritative.
 - Never ask the user for SSH credentials, key paths, proxy settings, or jump-host details when Netcatty session access already exists.
 - Do not pause to explain the plan, re-read this skill, or design scripts before trying that shortest path.
 - When presenting structured results, prefer a concise table if it fits clearly.
 
+Examples:
+
+- On Windows, if a literal shell command line is required, use the host-provided prefix with the system launcher available in the environment, such as `cmd.exe` or Windows PowerShell; do not assume PowerShell 7 `pwsh.exe` exists.
+- On macOS or Linux, use the host-provided prefix directly, or the system shell already available in that environment when a shell command line is unavoidable.
+- When the execution surface accepts argv-style calls, use the Netcatty launcher path as the executable and pass subcommands and flags as separate arguments instead of wrapping it in another shell.
+
 ## References
 
 - Exec and session workflow: `references/exec.md`