test(ai): keep image bridge fixture type safe

Add a Move to group action for the selected hosts, reusing existing group moves and saving the selection once. Omit the hidden synthetic General destination.

Related to #3194; marquee selection and dragging a selection are outside this change.

65 focused checks, lint, build and real grid/list mouse/keyboard/cancel/reload/single-host drag checks pass. Current-head remote review and both CI jobs pass.

application/AppHandlers.connect.test.ts

@@ -7,6 +7,7 @@ import {
   handleKeyboardInteractiveSubmitImpl,
   handleTrayPanelConnectRequestImpl,
 } from './app/AppHandlers.ts';
+import { resolveShellSetting } from '../lib/useDiscoveredShells.ts';
 import type { Host } from '../types';
 
 const baseHost: Host = {
@@ -398,3 +399,69 @@ test('keyboard-interactive submit keeps the prompt and password unchanged when d
   assert.equal(hosts[0].password, 'old-password');
   assert.deepEqual(errors, ['Request not found']);
 });
+
+test('local host without explicit shell resolves the configured Settings shell', () => {
+  const connectedHosts: Host[] = [];
+  const localHost: Host = { ...baseHost, id: 'local-1', hostname: 'localhost', protocol: 'local' };
+  const discoveredShells = [
+    { id: 'wsl-ubuntu', name: 'Ubuntu (WSL)', command: 'wsl.exe', args: ['-d', 'Ubuntu'] },
+  ];
+
+  handleConnectToHostImpl(
+    () => ({
+      addConnectionLog: () => {},
+      connectToHost: (host: Host) => {
+        connectedHosts.push(host);
+        return 'local-session';
+      },
+      discoveredShells,
+      identities: [],
+      keys: [],
+      resolveEffectiveHost: (host: Host) => host,
+      resolveHostAuth: () => ({ username: '' }),
+      resolveShellSetting,
+      systemInfoRef: { current: { username: 'local-user', hostname: 'local-host' } },
+      terminalSettings: { localShell: 'wsl-ubuntu' },
+    }) as never,
+    localHost,
+  );
+
+  assert.equal(connectedHosts.length, 1);
+  assert.equal(connectedHosts[0].localShell, 'wsl.exe');
+  assert.deepEqual(connectedHosts[0].localShellArgs, ['-d', 'Ubuntu']);
+  assert.equal(connectedHosts[0].localShellName, 'Ubuntu (WSL)');
+});
+
+test('local host with an explicit shell keeps it (no Settings fallback)', () => {
+  const connectedHosts: Host[] = [];
+  const localHost: Host = {
+    ...baseHost,
+    id: 'local-2',
+    hostname: 'localhost',
+    protocol: 'local',
+    localShell: 'pwsh',
+  };
+
+  handleConnectToHostImpl(
+    () => ({
+      addConnectionLog: () => {},
+      connectToHost: (host: Host) => {
+        connectedHosts.push(host);
+        return 'local-session-2';
+      },
+      discoveredShells: [],
+      identities: [],
+      keys: [],
+      resolveEffectiveHost: (host: Host) => host,
+      resolveHostAuth: () => ({ username: '' }),
+      resolveShellSetting,
+      systemInfoRef: { current: { username: 'local-user', hostname: 'local-host' } },
+      terminalSettings: { localShell: 'wsl-ubuntu' },
+    }) as never,
+    localHost,
+  );
+
+  assert.equal(connectedHosts.length, 1);
+  assert.equal(connectedHosts[0].localShell, 'pwsh');
+  assert.equal(connectedHosts[0].localShellName, undefined);
+});

application/app/AppHandlers.ts

@@ -4,6 +4,7 @@ import type { Host, HostProtocol, TerminalSession } from '../../types';
 import type { PassphraseRequest } from '../../components/PassphraseModal';
 import type { TerminalPopupPayload } from '../../domain/systemManager/types';
 import { getEffectiveHostDistro, classifyDistroId, hostRestrictsExtraSshChannels, shouldProbeSessionCwd } from '../../domain/host';
+import { resolveHostDefaultLocalShell } from '../../domain/localShellHost';
 import { getAvailablePaneMagnificationController } from '../../domain/paneMagnification';
 import { sanitizeHostIconFields } from '../../domain/hostIcon';
 import { resolveEffectiveTerminalProtocol } from '../../domain/terminalProtocol';
@@ -204,7 +205,10 @@ export function handleTrayPanelConnectImpl(getCtx: AppContextGetter, hostId: str
       hostId: host.id,
       hostLabel: host.label,
       hostname: host.hostname,
-      username: resolvedAuth.username || 'root',
+      // Local-shell vault hosts carry no SSH credentials, so log the system
+      // user like local terminals do (see handleConnectToHostImpl) instead of
+      // 'root' or an inherited group SSH username.
+      username: protocol === 'local' ? username : (resolvedAuth.username || 'root'),
       protocol,
       ...getLogHostVisualSnapshot(effectiveHost),
       startTime: Date.now(),
@@ -1104,11 +1108,15 @@ export function handleCreateLocalTerminalImpl(
 }
 
 export function handleConnectToHostImpl(getCtx: AppContextGetter, host: Host, hidden = false) {
-  const { addConnectionLog, connectToHost, identities, keys, resolveEffectiveHost, resolveHostAuth, systemInfoRef } = getCtx();
+  const { addConnectionLog, connectToHost, discoveredShells, identities, keys, resolveEffectiveHost, resolveHostAuth, resolveShellSetting, systemInfoRef, terminalSettings } = getCtx();
 {
     const { username, hostname: localHost } = systemInfoRef.current;
 
-    const effectiveHost = resolveEffectiveHost(host);
+    const effectiveHost = resolveHostDefaultLocalShell(resolveEffectiveHost(host), {
+      discoveredShells,
+      resolveShellSetting,
+      terminalSettings,
+    });
 
     // Handle serial hosts separately
     if (effectiveHost.protocol === 'serial') {
@@ -1138,7 +1146,10 @@ export function handleConnectToHostImpl(getCtx: AppContextGetter, host: Host, hi
       hostId: host.id,
       hostLabel: host.label,
       hostname: host.hostname,
-      username: resolvedAuth.username || 'root',
+      // Local-shell vault hosts carry no SSH credentials, so log the system
+      // user like local terminals do (see handleCreateLocalTerminalImpl)
+      // instead of 'root' or an inherited group SSH username.
+      username: protocol === 'local' ? username : (resolvedAuth.username || 'root'),
       protocol,
       ...getLogHostVisualSnapshot(effectiveHost),
       startTime: Date.now(),
@@ -1186,8 +1197,13 @@ export function hasMultipleProtocolsImpl(getCtx: AppContextGetter, host: Host) {
     // Gates the protocol picker (legacy name kept for its existing wiring).
     // Only prompt when Telnet is available but isn't the host's default protocol;
     // SSH-only, SSH+Mosh and Telnet-default all connect directly.
+    // SSH-only guard, matching VaultView's handleHostConnect: local-shell and
+    // serial hosts must always launch their own transport, never offer
+    // SSH/Telnet pickers driven by an inherited group Telnet flag. Hosts
+    // without an explicit protocol are legacy SSH entries.
     const effective = resolveEffectiveHost(host);
-    return Boolean(effective.telnetEnabled) && effective.protocol !== 'telnet';
+    const effectiveProtocol = effective.protocol ?? 'ssh';
+    return effectiveProtocol === 'ssh' && Boolean(effective.telnetEnabled);
   }
 }
 

application/app/AppHostEditorLayer.test.ts

@@ -34,6 +34,17 @@ test('serial targets use the serial editor', () => {
   );
 });
 
+test('local targets use the local shell editor', () => {
+  assert.equal(
+    resolveWorkSurfaceHostEditorKind({
+      mode: 'edit',
+      openedHost: host({ protocol: 'local' }),
+      requestId: 3,
+    }),
+    'local',
+  );
+});
+
 test('new and ssh targets use the standard editor', () => {
   assert.equal(
     resolveWorkSurfaceHostEditorKind({ mode: 'new', defaultGroup: null, requestId: 1 }),
@@ -71,8 +82,8 @@ test('editor overlay leaves the work surface interactive outside the panel', ()
 
   assert.match(source, /pointer-events-none absolute inset-0 z-40/);
   assert.match(source, /\[&>\*\]:pointer-events-auto/);
-  assert.equal((source.match(/className="pointer-events-auto"/g) ?? []).length, 2);
-  assert.equal((source.match(/layout="overlay"/g) ?? []).length, 2);
+  assert.equal((source.match(/className="pointer-events-auto"/g) ?? []).length, 3);
+  assert.equal((source.match(/layout="overlay"/g) ?? []).length, 3);
 });
 
 test('editor host panels share vault resize width persistence', () => {
@@ -81,7 +92,7 @@ test('editor host panels share vault resize width persistence', () => {
   assert.match(source, /STORAGE_KEY_VAULT_HOST_PANEL_WIDTH/);
   assert.match(source, /resizable:\s*true/);
   assert.match(source, /\{\.\.\.hostPanelResizeProps\}/);
-  assert.equal((source.match(/\{\.\.\.hostPanelResizeProps\}/g) ?? []).length, 2);
+  assert.equal((source.match(/\{\.\.\.hostPanelResizeProps\}/g) ?? []).length, 3);
 });
 
 test('editor stays mounted while another app surface is active', () => {

application/app/AppHostEditorLayer.tsx

@@ -5,6 +5,7 @@ import type { EditorTabChrome } from '../state/editorTabStore';
 import type { LogView } from '../state/logViewState';
 import { useI18n } from '../i18n/I18nProvider';
 import HostDetailsPanel from '../../components/HostDetailsPanel';
+import LocalShellHostDetailsPanel from '../../components/LocalShellHostDetailsPanel';
 import SerialHostDetailsPanel from '../../components/SerialHostDetailsPanel';
 import { PortalContainerProvider } from '../../components/ui/portal-container';
 import { resolveGroupDefaults } from '../../domain/groupConfig';
@@ -22,14 +23,16 @@ import type {
 } from '../../types';
 import { useWorkSurfaceVisible } from './AppHostEditorSurface';
 
-export type WorkSurfaceHostEditorKind = 'standard' | 'serial';
+export type WorkSurfaceHostEditorKind = 'standard' | 'serial' | 'local';
 
 export function resolveWorkSurfaceHostEditorKind(
   target: WorkSurfaceHostEditorTarget,
 ): WorkSurfaceHostEditorKind {
   return target.mode === 'edit' && target.openedHost.protocol === 'serial'
     ? 'serial'
-    : 'standard';
+    : target.mode === 'edit' && target.openedHost.protocol === 'local'
+      ? 'local'
+      : 'standard';
 }
 
 function addGroupAndAncestors(groups: Set<string>, path: string | null | undefined) {
@@ -160,7 +163,18 @@ export const AppHostEditorLayer: React.FC<AppHostEditorLayerProps> = ({
       style={getAppHostEditorLayerStyle(surfaceVisible)}
     >
       <PortalContainerProvider container={portalContainer}>
-        {target.mode === 'edit' && target.openedHost.protocol === 'serial' ? (
+        {target.mode === 'edit' && target.openedHost.protocol === 'local' ? (
+          <LocalShellHostDetailsPanel
+            key={editorKey}
+            initialData={target.openedHost}
+            groups={groups}
+            onSave={onSave}
+            onCancel={onCancel}
+            layout="overlay"
+            className="pointer-events-auto"
+            {...hostPanelResizeProps}
+          />
+        ) : target.mode === 'edit' && target.openedHost.protocol === 'serial' ? (
           <SerialHostDetailsPanel
             key={editorKey}
             initialData={target.openedHost}

application/app/AppSideEffects.localShell.test.ts

@@ -0,0 +1,35 @@
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import test from 'node:test';
+import ts from 'typescript';
+import { createLocalShellHost, resolveHostDefaultLocalShell } from '../../domain/localShellHost';
+import { createHostTerminalSession } from '../state/sessionFactories';
+
+// Exercise the production application callback, including its async command
+// resolution boundary, before the state hook snapshots the shell type.
+const source = readFileSync(new URL('./AppSideEffects.tsx', import.meta.url), 'utf8');
+const callback = source.match(/const handleRunSnippet = useCallback\(([\s\S]*?)\n {2}\);/)?.[1];
+assert.ok(callback);
+const compiled = ts.transpile(`const run = useCallback(${callback});`, { target: ts.ScriptTarget.ES2022 });
+
+for (const script of [false, true]) {
+  test(`saved default local shell is resolved before ${script ? 'script' : 'snippet'} sessions are created`, async () => {
+    let session: ReturnType<typeof createHostTerminalSession> | undefined;
+    const run = new Function('useCallback', 'isScriptSnippet', 'runSnippet', 'resolveSnippetCommand', 'resolveEffectiveHost', `${compiled} return run;`)(
+      (value: unknown) => value,
+      () => script,
+      (_snippet: unknown, hosts: ReturnType<typeof createLocalShellHost>[]) => {
+        session = createHostTerminalSession('snippet-local', hosts[0]);
+      },
+      async () => 'echo hello',
+      (host: ReturnType<typeof createLocalShellHost>) => resolveHostDefaultLocalShell(host, {
+        terminalSettings: { localShell: 'cmd' },
+        resolveShellSetting: () => ({ command: 'cmd.exe' }),
+      }),
+    );
+    await run({ id: 'snippet-1' }, [createLocalShellHost({ os: 'windows' })]);
+    assert.equal(session?.protocol, 'local');
+    assert.equal(session?.localShell, 'cmd.exe');
+    assert.equal(session?.shellType, 'cmd');
+  });
+}

application/app/AppSideEffects.tsx

@@ -38,6 +38,7 @@ import {
 import { isTerminalBootEpochCurrent } from '../../domain/terminalBootEpoch';
 import { useI18n } from '../i18n/I18nProvider';
 import { matchesKeyBinding } from '../../domain/models';
+import { resolveHostDefaultLocalShell } from '../../domain/localShellHost';
 import { resolveGroupDefaults, applyGroupDefaults } from '../../domain/groupConfig';
 import { upsertKnownHost } from '../../domain/knownHosts';
 import { materializeHostProxyProfile } from '../../domain/proxyProfiles';
@@ -53,6 +54,7 @@ import {
 } from '../../domain/terminalAppearance';
 import { selectConnectionLogForTerminalDataCapture } from '../../domain/connectionLog';
 import { collectSessionIds } from '../../domain/workspace';
+import { useHostOpenSessionReuse } from '../state/useHostOpenSessionReuse';
 import type { PaneMagnificationController } from '../../domain/paneMagnification';
 import { resolveCloseIntent } from '../state/resolveCloseIntent';
 import { resolveSnippetsShortcutIntent } from '../state/resolveSnippetsShortcutIntent';
@@ -269,22 +271,6 @@ export function AppSideEffects() {
     renameSessionInline,
   } = sessionState;
 
-  // Presentation-field thrash stays off Host bags (Hosts use retainStable);
-  // AppSideEffects only needs host/session maps for glue handlers and effects.
-  const handleRunSnippet = useCallback(
-    async (snippet: Snippet, targetHosts: Host[]) => {
-      if (targetHosts.length === 0) return;
-      if (isScriptSnippet(snippet)) {
-        runSnippet(snippet, targetHosts);
-        return;
-      }
-      const command = await resolveSnippetCommand(snippet);
-      if (command === null) return;
-      runSnippet(snippet, targetHosts, command);
-    },
-    [runSnippet],
-  );
-
   // Presence-only list: keystrokes must not rebuild App domains / TopTabs structure.
   const editorTabs = useEditorTabChromeList();
 
@@ -1366,8 +1352,32 @@ export function AppSideEffects() {
           { validProxyProfileIds: proxyProfileIdSet },
         )
       : applyGroupDefaults(host, {}, { validProxyProfileIds: proxyProfileIdSet });
-    return materializeHostProxyProfile(withGroupDefaults, proxyProfiles);
-  }, [groupConfigs, proxyProfileIdSet, proxyProfiles]);
+    const effectiveHost = materializeHostProxyProfile(withGroupDefaults, proxyProfiles);
+    // Local-shell vault hosts saved with "System default shell" carry no
+    // localShell; resolve the Settings → Terminal shell here at the shared
+    // effective-host boundary so every launch path (connect, tray/dock open,
+    // workspace creation/append, tunnels) uses the configured shell instead
+    // of silently falling back to the backend OS default shell.
+    return resolveHostDefaultLocalShell(effectiveHost, {
+      discoveredShells,
+      resolveShellSetting,
+      terminalSettings,
+    });
+  }, [groupConfigs, proxyProfileIdSet, proxyProfiles, discoveredShells, terminalSettings]);
+
+  const handleRunSnippet = useCallback(
+    async (snippet: Snippet, targetHosts: Host[]) => {
+      if (targetHosts.length === 0) return;
+      if (isScriptSnippet(snippet)) {
+        runSnippet(snippet, targetHosts.map(resolveEffectiveHost));
+        return;
+      }
+      const command = await resolveSnippetCommand(snippet);
+      if (command === null) return;
+      runSnippet(snippet, targetHosts.map(resolveEffectiveHost), command);
+    },
+    [runSnippet, resolveEffectiveHost],
+  );
 
   const createWorkspaceWithEffectiveHosts = useCallback((name: string, selectedHosts: Host[]) => {
     createWorkspaceWithHosts(name, selectedHosts.map(resolveEffectiveHost));
@@ -1398,14 +1408,17 @@ export function AppSideEffects() {
     return handleConnectToHostImpl(() => ({
       addConnectionLog,
       connectToHost,
+      discoveredShells,
       host,
       identities,
       keys,
       resolveEffectiveHost: effectiveHostResolver,
       resolveHostAuth,
+      resolveShellSetting,
       systemInfoRef,
+      terminalSettings,
     }), host, hidden);
-  }, [addConnectionLog, connectToHost, resolveEffectiveHost, identities, keys]);
+  }, [addConnectionLog, connectToHost, resolveEffectiveHost, identities, keys, discoveredShells, terminalSettings]);
 
   const handleConnectToHostWithTabName = useCallback((host: Host, tabName?: string) => {
     const sessionId = handleConnectToHost(host);
@@ -1432,6 +1445,10 @@ export function AppSideEffects() {
     return { ok: true as const, sessionId, host };
   }, [handleConnectToHost]);
 
+  const findExistingSessionForHostForVaultAgent = useHostOpenSessionReuse({
+    sessions, hosts, keys, identities, resolveEffectiveHost,
+  });
+
   const closeSessionForVaultAgent = useCallback((sessionId: string) => {
     if (!sessions.some((session) => session.id === sessionId)) {
       return { ok: false as const, error: `Session "${sessionId}" was not found.` };
@@ -1474,6 +1491,7 @@ export function AppSideEffects() {
     stopTunnel,
     stopRuleTunnels,
     openHost: openHostForVaultAgent,
+    findExistingSessionForHost: findExistingSessionForHostForVaultAgent,
     closeSession: closeSessionForVaultAgent,
     getScriptSessionMeta: (sessionId) => sessions.find((session) => session.id === sessionId),
   });

application/app/AppView.tsx

@@ -37,6 +37,7 @@ import { useExternalMcpToggleState } from '../state/useExternalMcpToggleState';
 import { selectPluginThemeTokens } from '../state/pluginContributionEnvironment';
 import { netcattyBridge } from '../../infrastructure/services/netcattyBridge';
 import { resolveEffectiveTerminalHost } from '../../domain/terminalHostResolution';
+import { useDefaultLocalShellContext } from '../../lib/useDiscoveredShells';
 import { getAvailablePaneMagnificationController } from '../../domain/paneMagnification';
 import { pluginViewTabStore, usePluginViewTabs } from '../state/pluginViewTabStore';
 import { buildPluginSettingScopeCatalog } from '../state/usePluginSettingScopeCatalog';
@@ -354,14 +355,16 @@ function AppViewInner({ domains }: AppViewProps) {
     [proxyProfiles],
   );
 
+  const defaultLocalShell = useDefaultLocalShellContext(terminalSettings);
   const resolveWorkspaceAppendHost = useCallback((host: typeof hosts[number]) => (
     resolveEffectiveTerminalHost({
       host,
       groupConfigs,
       proxyProfiles,
       validProxyProfileIds,
+      defaultLocalShell,
     })
-  ), [groupConfigs, proxyProfiles, validProxyProfileIds]);
+  ), [groupConfigs, proxyProfiles, validProxyProfileIds, defaultLocalShell]);
 
   const handleAppendHostToWorkspace = useCallback((workspaceId: string, hostId: string) => {
     const host = hosts.find((entry) => entry.id === hostId);

application/i18n/locales/en/ai.ts

@@ -522,6 +522,8 @@ export const enAiMessages: Messages = {
   'ai.chat.hoursAgo': '{n}h ago',
   'ai.chat.daysAgo': '{n}d ago',
   'ai.chat.newChat': 'New Chat',
+  'ai.chat.undoLastTurn': 'Undo last turn',
+  'ai.chat.undoLastTurnNotice': "Original chat kept. Commands and file changes are not undone. Return to the original chat for saved full outputs and existing background tasks.",
   'ai.chat.allSessions': 'All Sessions',
   'ai.chat.loadEarlierMessages': 'Load earlier messages ({n} more)',
   'ai.chat.jumpNav': 'Jump to message',
@@ -533,6 +535,8 @@ export const enAiMessages: Messages = {
   'ai.chat.searchSessionsHint': 'Searches titles, prioritizing newer messages and entries. For long messages and tool outputs, only a limited portion at the beginning is searched. This is not full-text search.',
   'ai.chat.noMatchingSessions': 'No matches in titles or recent retained content',
   'ai.chat.noSessions': 'No previous sessions',
+  'ai.chat.forkFromHere': 'Fork from here',
+  'ai.chat.forkCreated': 'Branched into a new chat — the original stays in history.',
   'ai.chat.retryHint': 'You can retry by sending your message again.',
   'ai.chat.approvalTimeout': 'Tool approval timed out after 5 minutes. You can retry by sending your message again.',
   'ai.chat.menuHosts': 'Hosts',

application/i18n/locales/en/core.ts

@@ -1123,6 +1123,7 @@ Highlight the focused split pane:
   'vault.tree.expandAll': 'Expand All',
   'vault.tree.collapseAll': 'Collapse All',
   'vault.hosts.newHost': 'New Host',
+  'vault.hosts.newLocalShell': 'Local Shell (CMD)',
   'vault.hosts.newGroup': 'New Group',
   'vault.hosts.import': 'Import',
   'vault.hosts.export': 'Export',
@@ -1148,6 +1149,9 @@ Highlight the focused split pane:
   'vault.hosts.deleteMultiple.success': 'Deleted {count} hosts',
   'vault.hosts.connectSelected': 'Connect ({count})',
   'vault.hosts.connectMultiple.success': 'Connecting {count} hosts',
+  'vault.hosts.moveSelected': 'Move to group ({count})',
+  'vault.hosts.moveSelected.description': 'Move the selected hosts to an existing group, or leave them ungrouped. Selected groups are not moved.',
+  'vault.hosts.moveMultiple.success': 'Moved {count} hosts to {group}',
   'vault.hosts.moveToGroup.success': 'Moved {host} to {group}',
   'vault.hosts.errors.nameRequired': 'Host name is required.',
   'vault.hosts.empty.title': 'Set up your hosts',

application/i18n/locales/en/vault.ts

@@ -1018,6 +1018,21 @@ export const enVaultMessages: Messages = {
   'hostDetails.addTag': 'Add a tag...',
   'hostDetails.createTag': 'Create tag',
   'hostDetails.createGroup': 'Create group',
+  // Local shell (CMD) host entries
+  'localShell.subtitle': 'Local Shell',
+  'localShell.panel.title': 'New Local Shell',
+  'localShell.panel.title.edit': 'Edit Local Shell',
+  'localShell.field.label': 'Name',
+  'localShell.field.labelPlaceholder': 'e.g. Project A · CMD',
+  'localShell.field.shell': 'Shell',
+  'localShell.field.shellDefault': 'System default shell',
+  'localShell.field.shellDefaultDesc': 'Leave empty to use the default local shell configured in Settings → Terminal.',
+  'localShell.field.shellEmpty': 'No shells found',
+  'localShell.field.shellResolved': 'Runs {command}',
+  'localShell.field.startDir': 'Start directory',
+  'localShell.field.startDirPlaceholder': 'Inherit global start directory (home if unset)',
+  'localShell.saveAndConnect': 'Save & Connect',
+
   'hostDetails.plugin.title': 'Plugin connection',
   'hostDetails.plugin.provider.placeholder': 'Select a connection provider',
   'hostDetails.plugin.provider.empty': 'No connection providers are installed',

application/i18n/locales/es/ai.ts

@@ -513,6 +513,8 @@ export const esAiMessages: Messages = {
   'ai.chat.hoursAgo': 'hace {n} h',
   'ai.chat.daysAgo': 'hace {n} d',
   'ai.chat.newChat': 'Nuevo chat',
+  'ai.chat.undoLastTurn': 'Deshacer el último turno',
+  'ai.chat.undoLastTurnNotice': "Se conserva el chat original. Los comandos y cambios de archivos no se deshacen. Consulta allí las salidas completas guardadas y las tareas en segundo plano existentes.",
   'ai.chat.allSessions': 'Todas las sesiones',
   'ai.chat.loadEarlierMessages': 'Cargar mensajes anteriores ({n} más)',
   'ai.chat.jumpNav': 'Ir al mensaje',
@@ -524,6 +526,8 @@ export const esAiMessages: Messages = {
   'ai.chat.searchSessionsHint': 'Busca en los títulos y da prioridad a los mensajes y entradas más recientes. De los mensajes largos y las salidas de herramientas, solo se busca una parte limitada del comienzo. No es una búsqueda de texto completo.',
   'ai.chat.noMatchingSessions': 'Sin coincidencias en títulos ni contenido reciente conservado',
   'ai.chat.noSessions': 'No hay sesiones anteriores',
+  'ai.chat.forkFromHere': 'Bifurcar desde aquí',
+  'ai.chat.forkCreated': 'Conversación bifurcada en un chat nuevo; el original permanece en el historial.',
   'ai.chat.retryHint': 'Puedes reintentar enviando tu mensaje de nuevo.',
   'ai.chat.approvalTimeout': 'La aprobación de la herramienta expiró después de 5 minutos. Puedes reintentar enviando tu mensaje de nuevo.',
   'ai.chat.menuHosts': 'Hosts',

application/i18n/locales/es/core.ts

@@ -1081,6 +1081,7 @@ Resalta el panel dividido enfocado:
   'vault.tree.expandAll': 'Expandir todo',
   'vault.tree.collapseAll': 'Contraer todo',
   'vault.hosts.newHost': 'Nuevo host',
+  'vault.hosts.newLocalShell': 'Shell local (CMD)',
   'vault.hosts.newGroup': 'Nuevo grupo',
   'vault.hosts.import': 'Importar',
   'vault.hosts.export': 'Exportar',
@@ -1106,6 +1107,9 @@ Resalta el panel dividido enfocado:
   'vault.hosts.deleteMultiple.success': 'Se eliminaron {count} hosts',
   'vault.hosts.connectSelected': 'Conectar ({count})',
   'vault.hosts.connectMultiple.success': 'Conectando {count} hosts',
+  'vault.hosts.moveSelected': 'Mover al grupo ({count})',
+  'vault.hosts.moveSelected.description': 'Mueve los hosts seleccionados a un grupo existente o los deja sin grupo. Los grupos seleccionados no se mueven.',
+  'vault.hosts.moveMultiple.success': 'Se movieron {count} hosts a {group}',
   'vault.hosts.moveToGroup.success': 'Se movió {host} a {group}',
   'vault.hosts.errors.nameRequired': 'Se requiere el nombre del host.',
   'vault.hosts.empty.title': 'Configura tus hosts',

application/i18n/locales/es/vault.ts

@@ -1008,6 +1008,21 @@ export const esVaultMessages: Messages = {
   'hostDetails.addTag': 'Agregar una etiqueta...',
   'hostDetails.createTag': 'Crear etiqueta',
   'hostDetails.createGroup': 'Crear grupo',
+  // Entradas de shell local (CMD) en la bóveda
+  'localShell.subtitle': 'Shell local',
+  'localShell.panel.title': 'Nueva shell local',
+  'localShell.panel.title.edit': 'Editar shell local',
+  'localShell.field.label': 'Nombre',
+  'localShell.field.labelPlaceholder': 'p. ej. Proyecto A · CMD',
+  'localShell.field.shell': 'Shell',
+  'localShell.field.shellDefault': 'Shell predeterminada del sistema',
+  'localShell.field.shellDefaultDesc': 'Si se deja vacío, se usa la shell local predeterminada configurada en Ajustes → Terminal.',
+  'localShell.field.shellEmpty': 'No se encontraron shells',
+  'localShell.field.shellResolved': 'Ejecuta {command}',
+  'localShell.field.startDir': 'Directorio de inicio',
+  'localShell.field.startDirPlaceholder': 'Heredar directorio inicial global (personal si no se configura)',
+  'localShell.saveAndConnect': 'Guardar y conectar',
+
   'hostDetails.plugin.title': 'Conexión de plugin',
   'hostDetails.plugin.provider.placeholder': 'Selecciona un proveedor de conexión',
   'hostDetails.plugin.provider.empty': 'No hay proveedores de conexión instalados',

application/i18n/locales/ru/ai.ts

@@ -469,6 +469,8 @@ export const ruAiMessages: Messages = {
   'ai.chat.hoursAgo': '{n}ч назад',
   'ai.chat.daysAgo': '{n}д назад',
   'ai.chat.newChat': 'Новый чат',
+  'ai.chat.undoLastTurn': 'Отменить последний ход',
+  'ai.chat.undoLastTurnNotice': "Исходный чат сохранён. Команды и изменения файлов не отменяются. Полные сохранённые результаты и фоновые задачи доступны в исходном чате.",
   'ai.chat.allSessions': 'Все сессии',
   'ai.chat.loadEarlierMessages': 'Загрузить более ранние сообщения (ещё {n})',
   'ai.chat.jumpNav': 'Перейти к сообщению',
@@ -480,6 +482,8 @@ export const ruAiMessages: Messages = {
   'ai.chat.searchSessionsHint': 'Поиск по заголовкам с приоритетом более новых сообщений и записей. В длинных сообщениях и результатах инструментов поиск охватывает только ограниченную начальную часть. Это не полнотекстовый поиск.',
   'ai.chat.noMatchingSessions': 'Нет совпадений в заголовках и недавнем сохранённом содержимом',
   'ai.chat.noSessions': 'Предыдущих сессий нет',
+  'ai.chat.forkFromHere': 'Ветвление отсюда',
+  'ai.chat.forkCreated': 'Разговор перенесён в новый чат; оригинал остаётся в истории.',
   'ai.chat.retryHint': 'Вы можете повторить попытку, отправив сообщение ещё раз.',
   'ai.chat.approvalTimeout': 'Время ожидания одобрения инструмента истекло через 5 минут. Вы можете повторить попытку, отправив сообщение ещё раз.',
   'ai.chat.menuHosts': 'Хосты',

application/i18n/locales/ru/vault.ts

@@ -102,6 +102,7 @@ export const ruVaultMessages: Messages = {
   'vault.tree.expandAll': 'Развернуть все',
   'vault.tree.collapseAll': 'Свернуть все',
   'vault.hosts.newHost': 'Новый хост',
+  'vault.hosts.newLocalShell': 'Локальная оболочка (CMD)',
   'vault.hosts.newGroup': 'Новая группа',
   'vault.hosts.import': 'Импорт',
   'vault.hosts.export': 'Экспорт',
@@ -127,6 +128,9 @@ export const ruVaultMessages: Messages = {
   'vault.hosts.deleteMultiple.success': 'Удалено хостов: {count}',
   'vault.hosts.connectSelected': 'Подключить ({count})',
   'vault.hosts.connectMultiple.success': 'Подключение хостов: {count}',
+  'vault.hosts.moveSelected': 'Переместить в группу ({count})',
+  'vault.hosts.moveSelected.description': 'Переместить выбранные хосты в существующую группу или оставить без группы. Выбранные группы не перемещаются.',
+  'vault.hosts.moveMultiple.success': 'Перемещено {count} хостов в {group}',
   'vault.hosts.moveToGroup.success': 'Хост {host} перемещён в {group}',
   'vault.hosts.empty.title': 'Настройте свои хосты',
   'vault.hosts.empty.desc': 'Сохраняйте хосты, чтобы быстро подключаться к серверам, виртуальным машинам и контейнерам.',
@@ -1051,6 +1055,21 @@ export const ruVaultMessages: Messages = {
   'hostDetails.addTag': 'Добавить тег...',
   'hostDetails.createTag': 'Создать тег',
   'hostDetails.createGroup': 'Создать группу',
+  // Записи локальной оболочки (CMD) в хранилище
+  'localShell.subtitle': 'Локальная оболочка',
+  'localShell.panel.title': 'Новая локальная оболочка',
+  'localShell.panel.title.edit': 'Изменить локальную оболочку',
+  'localShell.field.label': 'Название',
+  'localShell.field.labelPlaceholder': 'напр. Проект A · CMD',
+  'localShell.field.shell': 'Оболочка',
+  'localShell.field.shellDefault': 'Системная оболочка по умолчанию',
+  'localShell.field.shellDefaultDesc': 'Если оставить пустым, используется локальная оболочка по умолчанию из Настройки → Терминал.',
+  'localShell.field.shellEmpty': 'Оболочки не найдены',
+  'localShell.field.shellResolved': 'Запускает {command}',
+  'localShell.field.startDir': 'Начальный каталог',
+  'localShell.field.startDirPlaceholder': 'Использовать общий начальный каталог (иначе домашний)',
+  'localShell.saveAndConnect': 'Сохранить и открыть',
+
   'hostDetails.plugin.title': 'Подключение плагина',
   'hostDetails.plugin.provider.placeholder': 'Выберите провайдер подключения',
   'hostDetails.plugin.provider.empty': 'Провайдеры подключения не установлены',

application/i18n/locales/undoLastTurnLocales.test.ts

@@ -0,0 +1,20 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import en from './en.ts';
+import ru from './ru.ts';
+import es from './es.ts';
+import zhCN from './zh-CN.ts';
+import zhTW from './zh-TW.ts';
+
+const UNDO_KEYS = [
+  'ai.chat.undoLastTurn',
+  'ai.chat.undoLastTurnNotice',
+] as const;
+
+test('Undo-last-turn UI is localized in every supported locale', () => {
+  for (const [name, messages] of Object.entries({ en, es, 'zh-CN': zhCN, 'zh-TW': zhTW, ru })) {
+    const missing = UNDO_KEYS.filter(key => !messages[key]);
+    assert.deepEqual(missing, [], `${name} is missing undo-last-turn labels`);
+  }
+});

application/i18n/locales/zh-CN/ai.ts

@@ -522,6 +522,8 @@ export const zhCNAiMessages: Messages = {
   'ai.chat.hoursAgo': '{n}小时前',
   'ai.chat.daysAgo': '{n}天前',
   'ai.chat.newChat': '新对话',
+  'ai.chat.undoLastTurn': '撤销上一轮',
+  'ai.chat.undoLastTurnNotice': "原对话已保留。已执行的命令和文件修改不会撤销；之前保存的完整输出和后台任务，请回原对话查看。",
   'ai.chat.allSessions': '所有会话',
   'ai.chat.loadEarlierMessages': '加载更早的消息（还有 {n} 条）',
   'ai.chat.jumpNav': '跳转到消息',
@@ -533,6 +535,8 @@ export const zhCNAiMessages: Messages = {
   'ai.chat.searchSessionsHint': '搜索标题，并优先搜索较新的消息和条目；超长消息及工具输出仅搜索开头的有限部分。这不是全文搜索。',
   'ai.chat.noMatchingSessions': '标题和近期保留的内容中没有匹配结果',
   'ai.chat.noSessions': '没有历史会话',
+  'ai.chat.forkFromHere': '从此处分叉',
+  'ai.chat.forkCreated': '已分叉到新对话，原对话保留在历史中。',
   'ai.chat.retryHint': '你可以重新发送消息来重试。',
   'ai.chat.approvalTimeout': '工具审批已超时（5 分钟）。你可以重新发送消息来重试。',
   'ai.chat.menuHosts': '主机',

application/i18n/locales/zh-CN/core.ts

@@ -740,6 +740,7 @@ export const zhCNCoreMessages: Messages = {
   'vault.tree.expandAll': '展开全部',
   'vault.tree.collapseAll': '折叠全部',
   'vault.hosts.newHost': '新建主机',
+  'vault.hosts.newLocalShell': '本地终端 (CMD)',
   'vault.hosts.newGroup': '新建分组',
   'vault.hosts.import': '导入',
   'vault.hosts.export': '导出',
@@ -765,6 +766,9 @@ export const zhCNCoreMessages: Messages = {
   'vault.hosts.deleteMultiple.success': '已删除 {count} 个主机',
   'vault.hosts.connectSelected': '连接 ({count})',
   'vault.hosts.connectMultiple.success': '正在连接 {count} 个主机',
+  'vault.hosts.moveSelected': '移动到分组 ({count})',
+  'vault.hosts.moveSelected.description': '将选中的主机移动到现有分组，也可移出分组。选中的分组本身不会移动。',
+  'vault.hosts.moveMultiple.success': '已将 {count} 个主机移动到 {group}',
   'vault.hosts.moveToGroup.success': '已将 {host} 移动到 {group}',
   'vault.hosts.errors.nameRequired': '主机名称不能为空。',
   'vault.hosts.empty.title': '设置你的主机',

application/i18n/locales/zh-CN/vault.ts

@@ -390,6 +390,21 @@ export const zhCNVaultMessages: Messages = {
   'hostDetails.addTag': '添加标签...',
   'hostDetails.createTag': '创建标签',
   'hostDetails.createGroup': '创建分组',
+  // 本地终端（CMD）主机条目
+  'localShell.subtitle': '本地终端',
+  'localShell.panel.title': '新建本地终端',
+  'localShell.panel.title.edit': '编辑本地终端',
+  'localShell.field.label': '名称',
+  'localShell.field.labelPlaceholder': '例如：项目 A · CMD',
+  'localShell.field.shell': 'Shell',
+  'localShell.field.shellDefault': '系统默认 Shell',
+  'localShell.field.shellDefaultDesc': '留空则使用设置 → 终端中配置的默认本地 Shell。',
+  'localShell.field.shellEmpty': '未发现可用 Shell',
+  'localShell.field.shellResolved': '启动 {command}',
+  'localShell.field.startDir': '启动目录',
+  'localShell.field.startDirPlaceholder': '继承全局起始目录（未设置时为主目录）',
+  'localShell.saveAndConnect': '保存并打开',
+
   'hostDetails.plugin.title': '插件连接',
   'hostDetails.plugin.provider.placeholder': '选择连接提供程序',
   'hostDetails.plugin.provider.empty': '未安装连接提供程序',

application/i18n/locales/zh-TW/ai.ts

@@ -512,6 +512,8 @@ export const zhTWAiMessages: Messages = {
   'ai.chat.hoursAgo': '{n}小時前',
   'ai.chat.daysAgo': '{n}天前',
   'ai.chat.newChat': '新對話',
+  'ai.chat.undoLastTurn': '復原上一輪',
+  'ai.chat.undoLastTurnNotice': "原對話已保留。已執行的命令和檔案修改不會復原；之前儲存的完整輸出和背景工作，請回原對話查看。",
   'ai.chat.allSessions': '所有工作階段',
   'ai.chat.loadEarlierMessages': '載入更早的訊息（還有 {n} 條）',
   'ai.chat.jumpNav': '跳轉到訊息',
@@ -523,6 +525,8 @@ export const zhTWAiMessages: Messages = {
   'ai.chat.searchSessionsHint': '搜尋標題，並優先搜尋較新的訊息與項目；超長訊息與工具輸出僅搜尋開頭的有限部分。這不是全文搜尋。',
   'ai.chat.noMatchingSessions': '標題和近期保留的內容中沒有符合的結果',
   'ai.chat.noSessions': '沒有歷史工作階段',
+  'ai.chat.forkFromHere': '從此處分叉',
+  'ai.chat.forkCreated': '已分叉到新對話，原對話保留在歷史中。',
   'ai.chat.retryHint': '你可以重新發送訊息來重試。',
   'ai.chat.approvalTimeout': '工具核准已超時（5 分鐘）。你可以重新發送訊息來重試。',
   'ai.chat.menuHosts': '主機',

application/i18n/locales/zh-TW/core.ts

@@ -742,6 +742,7 @@ export const zhTWCoreMessages: Messages = {
   'vault.tree.expandAll': '展開全部',
   'vault.tree.collapseAll': '摺疊全部',
   'vault.hosts.newHost': '新增主機',
+  'vault.hosts.newLocalShell': '本地終端 (CMD)',
   'vault.hosts.newGroup': '新增群組',
   'vault.hosts.import': '匯入',
   'vault.hosts.export': '匯出',
@@ -767,6 +768,9 @@ export const zhTWCoreMessages: Messages = {
   'vault.hosts.deleteMultiple.success': '已刪除 {count} 個主機',
   'vault.hosts.connectSelected': '連線 ({count})',
   'vault.hosts.connectMultiple.success': '正在連線 {count} 個主機',
+  'vault.hosts.moveSelected': '移動到群組 ({count})',
+  'vault.hosts.moveSelected.description': '將選取的主機移動到現有群組，也可移出群組。選取的群組本身不會移動。',
+  'vault.hosts.moveMultiple.success': '已將 {count} 個主機移動到 {group}',
   'vault.hosts.moveToGroup.success': '已將 {host} 移動到 {group}',
   'vault.hosts.errors.nameRequired': '主機名稱不能為空。',
   'vault.hosts.empty.title': '設定你的主機',

application/i18n/locales/zh-TW/vault.ts

@@ -390,6 +390,21 @@ export const zhTWVaultMessages: Messages = {
   'hostDetails.addTag': '新增標籤...',
   'hostDetails.createTag': '建立標籤',
   'hostDetails.createGroup': '建立群組',
+  // 本地終端（CMD）主機項目
+  'localShell.subtitle': '本地終端',
+  'localShell.panel.title': '新增本地終端',
+  'localShell.panel.title.edit': '編輯本地終端',
+  'localShell.field.label': '名稱',
+  'localShell.field.labelPlaceholder': '例如：專案 A · CMD',
+  'localShell.field.shell': 'Shell',
+  'localShell.field.shellDefault': '系統預設 Shell',
+  'localShell.field.shellDefaultDesc': '留空則使用設定 → 終端中設定的預設本地 Shell。',
+  'localShell.field.shellEmpty': '未找到可用的 Shell',
+  'localShell.field.shellResolved': '啟動 {command}',
+  'localShell.field.startDir': '啟動目錄',
+  'localShell.field.startDirPlaceholder': '繼承全域起始目錄（未設定時為主目錄）',
+  'localShell.saveAndConnect': '儲存並開啟',
+
   'hostDetails.plugin.title': '外掛程式連線',
   'hostDetails.plugin.provider.placeholder': '選擇連線提供者',
   'hostDetails.plugin.provider.empty': '尚未安裝連線提供者',

application/state/sessionFactories.localVaultHost.test.ts

@@ -0,0 +1,244 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { createHostTerminalSession } from "./sessionFactories.ts";
+import { createLocalTerminalSession } from "./sessionFactories.ts";
+import { resolveHostDefaultLocalShell } from "../../domain/localShellHost";
+import { resolveTerminalSessionHost } from "../../domain/terminalHostResolution";
+import type { Host } from "../../domain/models";
+
+const localVaultHost = (overrides: Partial<Host> = {}): Host => ({
+  id: "local-vault-1",
+  label: "Project A CMD",
+  hostname: "localhost",
+  username: "",
+  group: "Projects/A",
+  tags: ["local"],
+  os: "linux",
+  protocol: "local",
+  createdAt: 0,
+  ...overrides,
+});
+
+test("createHostTerminalSession copies local shell fields for local vault hosts", () => {
+  const host = localVaultHost({
+    localShell: "wsl-ubuntu",
+    localShellArgs: ["--cd", "/work"],
+    localShellName: "Ubuntu (WSL)",
+    localShellIcon: "ubuntu",
+    localStartDir: "/work",
+  });
+  const session = createHostTerminalSession("session-1", host);
+
+  assert.equal(session.protocol, "local");
+  assert.equal(session.hostId, "local-vault-1");
+  assert.equal(session.localShell, "wsl-ubuntu");
+  assert.deepEqual(session.localShellArgs, ["--cd", "/work"]);
+  assert.equal(session.localShellName, "Ubuntu (WSL)");
+  assert.equal(session.localShellIcon, "ubuntu");
+  assert.equal(session.localStartDir, "/work");
+});
+
+test("createHostTerminalSession does not add local shell fields to SSH hosts", () => {
+  const host: Host = {
+    ...localVaultHost({ protocol: "ssh", hostname: "example.com", port: 22 }),
+  } as Host;
+  const session = createHostTerminalSession("session-2", host);
+
+  assert.equal(session.protocol, "ssh");
+  assert.equal(session.localShell, undefined);
+  assert.equal(session.localShellName, undefined);
+  assert.equal(session.shellType, undefined);
+});
+
+test("createHostTerminalSession classifies the shell for CMD/PowerShell local vault hosts", () => {
+  const cmd = createHostTerminalSession("session-cmd", localVaultHost({ localShell: "cmd", os: "windows" }));
+  assert.equal(cmd.shellType, "cmd");
+
+  const pwsh = createHostTerminalSession("session-pwsh", localVaultHost({ localShell: "pwsh", os: "windows" }));
+  assert.equal(pwsh.shellType, "powershell");
+
+  // Discovered shell IDs persisted by the local-shell editor are not
+  // executable basenames, but they still resolve to POSIX shells at spawn
+  // time — WSL distros, Git Bash, and Cygwin all run a POSIX shell.
+  const wslId = createHostTerminalSession("session-wsl-id", localVaultHost({ localShell: "wsl-ubuntu", os: "windows" }));
+  assert.equal(wslId.shellType, "posix");
+
+  const gitBash = createHostTerminalSession("session-git-bash", localVaultHost({ localShell: "git-bash", os: "windows" }));
+  assert.equal(gitBash.shellType, "posix");
+
+  const cygwin = createHostTerminalSession("session-cygwin", localVaultHost({ localShell: "cygwin", os: "windows" }));
+  assert.equal(cygwin.shellType, "posix");
+
+  // Unix discovery emits disambiguated path-slug IDs when multiple
+  // installations share a basename (e.g. /bin/bash vs
+  // /opt/homebrew/bin/bash); the backend launches the resolved command, so
+  // the session must classify as that command's shell type, not "unknown".
+  const slugBash = createHostTerminalSession("session-slug-bash", localVaultHost({ localShell: "bin-bash", os: "macos" }));
+  assert.equal(slugBash.shellType, "posix");
+
+  const slugHomebrewBash = createHostTerminalSession(
+    "session-slug-homebrew",
+    localVaultHost({ localShell: "opt-homebrew-bin-bash", os: "macos" }),
+  );
+  assert.equal(slugHomebrewBash.shellType, "posix");
+
+  const customPowershellPath = createHostTerminalSession(
+    "session-pwsh-path",
+    localVaultHost({ localShell: "C:\\Program Files\\PowerShell\\7\\pwsh.exe", os: "windows" }),
+  );
+  assert.equal(customPowershellPath.shellType, "powershell");
+
+  // Default-shell hosts (empty localShell) launch the machine's OS default
+  // shell (the backend's own detection), so classification must use the
+  // runtime platform — not the saved host.os, which may describe a machine
+  // the host was synced/imported from. Node 22's navigator.userAgent is
+  // always "Node.js/<version>", so this test environment always classifies
+  // as POSIX regardless of the CI runner's real OS.
+  const windowsSyncedDefault = createHostTerminalSession("session-win-default", localVaultHost({ os: "windows" }));
+  assert.equal(windowsSyncedDefault.shellType, "posix");
+
+  const posixDefault = createHostTerminalSession("session-posix-default", localVaultHost({ os: "linux" }));
+  assert.equal(posixDefault.shellType, "posix");
+
+  const unknownCustom = createHostTerminalSession(
+    "session-unknown",
+    localVaultHost({ localShell: "/usr/local/bin/exotic-shell", os: "linux" }),
+  );
+  assert.equal(unknownCustom.shellType, "unknown");
+});
+
+test("createLocalTerminalSession is unaffected by vault local hosts", () => {
+  const session = createLocalTerminalSession("session-3", { shellName: "CMD" });
+  assert.equal(session.hostId, "local-terminal");
+  assert.equal(session.localShellName, "CMD");
+});
+
+test("createHostTerminalSession snapshots an explicit no-args local shell as an empty array", () => {
+  // Legacy vault hosts can predate localShellArgs, so the field may be
+  // absent on the Host; the session snapshot must still distinguish
+  // "launched with no args" ([]) from "no metadata" (undefined).
+  const host = localVaultHost({
+    localShell: "cmd",
+    localShellName: "Command Prompt",
+    os: "windows",
+  });
+  const session = createHostTerminalSession("session-noargs", host);
+
+  assert.ok(Array.isArray(session.localShellArgs), "args snapshot must be present");
+  assert.deepEqual(session.localShellArgs, []);
+});
+
+test("resolveTerminalSessionHost does not merge edited host args into a no-args local snapshot", () => {
+  const launchTimeHost = localVaultHost({
+    localShell: "cmd",
+    localShellName: "Command Prompt",
+    os: "windows",
+  });
+  const session = createHostTerminalSession("session-1", launchTimeHost);
+
+  // The saved host was later edited to a shell with args; the snapshot taken
+  // at launch time must win so the clone relaunches CMD, not WSL.
+  const editedHost: Host = {
+    ...launchTimeHost,
+    label: "Edited WSL",
+    localShell: "wsl-ubuntu",
+    localShellArgs: ["--cd", "/elsewhere"],
+    localShellName: "Ubuntu (WSL)",
+    localStartDir: "/elsewhere",
+  };
+
+  const resolved = resolveTerminalSessionHost({
+    session,
+    hosts: [editedHost],
+    groupConfigs: [],
+    proxyProfiles: [],
+    localOs: "windows",
+  });
+
+  assert.equal(resolved.localShell, "cmd");
+  assert.deepEqual(resolved.localShellArgs, []);
+  assert.equal(resolved.localShellName, "Command Prompt");
+});
+
+test("createHostTerminalSession snapshots an inherited start directory for Copy Tab", () => {
+  // The saved host has no directory of its own, so the starter launches in
+  // Settings > Terminal's localStartDir. That effective directory has to be
+  // recorded now; overlay falls back to the host or the current setting when
+  // the session field is missing.
+  const saved = localVaultHost({
+    localShell: "bash",
+    localShellName: "Bash",
+    localStartDir: "",
+  });
+  const effective = resolveHostDefaultLocalShell(saved, {
+    terminalSettings: { localStartDir: "/home/alice/global" },
+  });
+  const session = createHostTerminalSession("session-inherit", effective);
+  assert.equal(session.localStartDir, "/home/alice/global");
+
+  const changedSettings = {
+    terminalSettings: { localShell: "fish", localStartDir: "/home/alice/changed" },
+  };
+  const afterSettingsChange = resolveTerminalSessionHost({
+    session,
+    hosts: [saved],
+    groupConfigs: [],
+    proxyProfiles: [],
+    localOs: "linux",
+    defaultLocalShell: changedSettings,
+  });
+  assert.equal(afterSettingsChange.localStartDir, "/home/alice/global");
+
+  const afterHostEdit = resolveTerminalSessionHost({
+    session,
+    hosts: [{ ...saved, localStartDir: "/home/alice/edited" }],
+    groupConfigs: [],
+    proxyProfiles: [],
+    localOs: "linux",
+    defaultLocalShell: changedSettings,
+  });
+  assert.equal(afterHostEdit.localStartDir, "/home/alice/global");
+});
+
+test("createHostTerminalSession snapshots an inherited start directory for a default shell host", () => {
+  const saved = localVaultHost();
+  const effective = resolveHostDefaultLocalShell(saved, {
+    terminalSettings: { localShell: "bash", localStartDir: "/home/alice/global" },
+    resolveShellSetting: () => ({ command: "/bin/bash", args: ["-l"] }),
+  });
+  const session = createHostTerminalSession("session-default-shell", effective);
+
+  assert.equal(session.localShell, "/bin/bash");
+  assert.deepEqual(session.localShellArgs, ["-l"]);
+  assert.equal(session.localStartDir, "/home/alice/global");
+});
+
+test("resolveHostDefaultLocalShell keeps an explicit start directory and ignores non-local hosts", () => {
+  const explicit = localVaultHost({ localShell: "bash", localStartDir: "/work" });
+  const resolvedExplicit = resolveHostDefaultLocalShell(explicit, {
+    terminalSettings: { localStartDir: "/home/alice/global" },
+  });
+  assert.equal(resolvedExplicit.localStartDir, "/work");
+  assert.equal(createHostTerminalSession("session-explicit", resolvedExplicit).localStartDir, "/work");
+
+  const ssh = localVaultHost({ protocol: "ssh", hostname: "example.com", port: 22 });
+  const resolvedSsh = resolveHostDefaultLocalShell(ssh, {
+    terminalSettings: { localStartDir: "/home/alice/global" },
+  });
+  assert.equal(resolvedSsh.localStartDir, undefined);
+  assert.equal(resolvedSsh, ssh);
+});
+
+test("saved local sessions use the ordinary local username marker without changing vault or SSH credentials", () => {
+  const saved = localVaultHost({ username: "" });
+  const ordinary = createLocalTerminalSession("ordinary-local");
+  const opened = createHostTerminalSession("saved-local", saved);
+  assert.equal(opened.username, ordinary.username);
+  assert.equal(opened.username, "local");
+  assert.equal(saved.username, "");
+  const remote = { ...saved, protocol: "ssh" as const, username: "remote-user" };
+  assert.equal(createHostTerminalSession("ssh-session", remote).username, "remote-user");
+  const resolved = resolveTerminalSessionHost({ session: opened, hosts: [saved], groupConfigs: [], proxyProfiles: [], localOs: "linux" });
+  assert.equal(resolved.username, ordinary.username, "terminal-run scripts receive the same local marker");
+});

application/state/sessionFactories.test.ts

@@ -4,7 +4,7 @@ import test from "node:test";
 import type { Host } from "../../domain/models";
 import { prepareSerialConfigForSavedHost } from "../../domain/serialBackspace";
 import { buildTelnetDeepLinkConnectionHost } from "../../domain/telnetDeepLink";
-import { resolveEffectiveTerminalHost } from "../../domain/terminalHostResolution";
+import { resolveEffectiveTerminalHost, resolveTerminalSessionHost } from "../../domain/terminalHostResolution";
 import {
   createHostTerminalSession,
   createSerialTerminalSession,
@@ -171,3 +171,16 @@ test("host session factories snapshot plugin connection configuration", () => {
   assert.deepEqual(workspace.pluginConnection, pluginConnection);
   assert.notEqual(workspace.pluginConnection, pluginConnection);
 });
+
+test("local sessions preserve intentionally absent display metadata when the saved shell changes", () => {
+  const original = host({ protocol: "local", hostname: "localhost", localShell: "/bin/bash" });
+  const source = createHostTerminalSession("original-bash", original);
+  const edited = { ...original, localShell: "/bin/zsh", localShellName: "Zsh", localShellIcon: "zsh" };
+  const copied = resolveTerminalSessionHost({ session: source, hosts: [edited], groupConfigs: [], proxyProfiles: [], localOs: "macos" });
+  assert.equal(copied.localShell, "/bin/bash");
+  assert.equal(copied.localShellName, "");
+  assert.equal(copied.localShellIcon, "");
+  const named = createHostTerminalSession("named-zsh", edited);
+  assert.equal(named.localShellName, "Zsh");
+  assert.equal(named.localShellIcon, "zsh");
+});

application/state/sessionFactories.ts

@@ -1,4 +1,5 @@
 import type { Host, SerialConfig, TerminalSession } from "../../domain/models";
+import { classifyLocalShellType } from "../../lib/localShell";
 
 export interface LocalTerminalOptions {
   shellType?: TerminalSession["shellType"];
@@ -18,6 +19,28 @@ export interface LocalTerminalOptions {
  */
 export const LOCAL_TERMINAL_HOST_ID = "local-terminal";
 
+/**
+ * [] captures the absence of custom arguments instead of inheriting them
+ * from a later host edit. The starter still applies backend defaults to []
+ * and undefined alike. Share the array to preserve pane equality checks.
+ */
+const EMPTY_LOCAL_SHELL_ARGS: string[] = [];
+
+/**
+ * Platform string describing the machine that is launching the session.
+ *
+ * Vault local hosts can be synced/imported from another OS, so their saved
+ * `host.os` describes the source machine. When the host has no explicit
+ * shell (`localShell` empty), `startLocalSession` spawns the current
+ * machine's OS default shell, so classification must fall back to the
+ * runtime platform — not the persisted host OS — or a Windows host opened
+ * on Linux would be tagged "powershell" while Bash actually runs.
+ */
+const runtimePlatformLike = (): string | undefined => {
+  if (typeof navigator === "undefined") return undefined;
+  return navigator.userAgent || navigator.platform || undefined;
+};
+
 export const createLocalTerminalSession = (
   sessionId: string,
   options?: LocalTerminalOptions,
@@ -113,6 +136,30 @@ export const createHostTerminalSession = (
     moshEnabled: host.moshEnabled,
     etEnabled: host.etEnabled,
     charset: host.charset,
+    // Local-shell vault hosts carry the per-host shell selection into the
+    // session (the bridge resolves discovered shell ids at spawn time).
+    // shellType matches ordinary local-terminal creation so captured-CWD
+    // restore can reject POSIX injection into CMD/PowerShell sessions.
+    ...(host.protocol === "local" ? {
+      username: "local",
+      // With an explicit shell the basename classifies it on any OS, so the
+      // saved host.os stays the fallback; a default-shell host launches the
+      // current machine's OS default, so classify against the runtime.
+      shellType: classifyLocalShellType(
+        host.localShell,
+        host.localShell?.trim() ? host.os : runtimePlatformLike(),
+      ),
+      localShell: host.localShell ?? "",
+      // Preserve field presence: an edited host must not contribute its args
+      // to a session that was launched with an explicit shell and no args.
+      localShellArgs: host.localShellArgs ?? EMPTY_LOCAL_SHELL_ARGS,
+      localShellName: host.localShellName ?? "",
+      localShellIcon: host.localShellIcon ?? "",
+      // Effective directory from resolveHostDefaultLocalShell, including a
+      // Settings directory the saved host inherits. Copy Tab overlays this
+      // snapshot, so a later settings or vault edit cannot move the relaunch.
+      localStartDir: host.localStartDir || "~",
+    } : {}),
     ...(host.ephemeral ? { ephemeralHost: true } : {}),
     ...(host.autoOpenSftpPanel ? { autoOpenSidePanel: "sftp" as const } : {}),
   };

application/state/terminalConnectionReuse.test.ts

@@ -224,3 +224,31 @@ test("split and copy session clones preserve isolated plugin connection snapshot
   assert.equal(split.reuseConnectionFromSessionId, undefined);
   assert.equal(copied.reuseConnectionFromSessionId, undefined);
 });
+
+for (const clone of [createSplitTerminalSessionClone, createCopiedTerminalSessionClone]) {
+  test(`${clone.name} keeps the type of an explicit local shell despite global settings`, () => {
+    for (const [localShell, shellType] of [["cmd.exe", "cmd"], ["pwsh.exe", "powershell"]] as const) {
+      const source = session({ protocol: "local", localShell, shellType });
+      const copied = clone(source, { id: "clone", localShellType: "posix" });
+      assert.equal(copied.localShell, localShell);
+      assert.equal(copied.shellType, shellType);
+      assert.equal(clone({ ...source, shellType: undefined },
+        { id: "legacy", localShellType: "posix" }).shellType, shellType);
+    }
+    const implicit = clone(session({ protocol: "local", shellType: "cmd" }),
+      { id: "clone-default", localShellType: "posix" });
+    assert.equal(implicit.shellType, "posix", "implicit shells still follow global settings");
+  });
+}
+
+test("copied backend-default local snapshot retains its shell semantics after global settings change", () => {
+  const source = session({ protocol: "local", localShell: "", localShellArgs: [], shellType: "powershell", localStartDir: "~" });
+  for (const clone of [
+    createCopiedTerminalSessionClone(source, { id: "copy-default-snapshot", localShellType: "posix" }),
+    createSplitTerminalSessionClone(source, { id: "split-default-snapshot", localShellType: "posix" }),
+  ]) {
+    assert.equal(clone.localShell, "");
+    assert.equal(clone.shellType, "powershell");
+    assert.equal(clone.localStartDir, "~");
+  }
+});

application/state/terminalConnectionReuse.ts

@@ -1,4 +1,5 @@
 import type { TerminalSession } from "../../domain/models";
+import { classifyLocalShellType } from "../../lib/localShell";
 
 type SftpReuseCandidate = Pick<
   TerminalSession,
@@ -44,7 +45,12 @@ function getClonedShellType(
   session: TerminalSession,
   localShellType?: TerminalSession["shellType"],
 ): TerminalSession["shellType"] {
-  return session.protocol === "local" ? localShellType : session.shellType;
+  if (session.protocol !== "local") return session.shellType;
+  // Clones retain an explicit per-session executable, so its shell type must
+  // survive a different global default (e.g. saved CMD with WSL in Settings).
+  return session.localShell !== undefined
+    ? (session.shellType ?? classifyLocalShellType(session.localShell))
+    : localShellType;
 }
 
 function createTerminalSessionClone(

application/state/useAIState.fork.test.ts

@@ -0,0 +1,134 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import React, { act } from 'react';
+import { createRoot } from 'react-dom/client';
+import { JSDOM } from 'jsdom';
+
+import type { AISession } from '../../infrastructure/ai/types.ts';
+import { getAgentRuntime } from '../../infrastructure/ai/harness/globalAgentRuntime.ts';
+import { useAIState } from './useAIState.ts';
+import { useAISessionsStore } from './aiSessionsStore.ts';
+import { setLatestAISessionsSnapshot } from './aiStateSnapshots.ts';
+
+const SOURCE_SESSION: AISession = {
+  id: 'chat-source',
+  title: 'Fork source',
+  agentId: 'catty',
+  scope: { type: 'terminal', targetId: 'terminal-a' },
+  messages: [
+    { id: 'user-1', role: 'user', content: 'first prompt', timestamp: 1 },
+    { id: 'assistant-1', role: 'assistant', content: 'first answer', timestamp: 2 },
+    {
+      id: 'user-2',
+      role: 'user',
+      content: 'bad last prompt',
+      timestamp: 3,
+      attachments: [
+        { base64Data: 'QUJD', mediaType: 'text/plain', filename: 'note.txt', lineCount: 2 },
+      ],
+    },
+    { id: 'assistant-2', role: 'assistant', content: 'bad answer', timestamp: 4 },
+  ],
+  createdAt: 1,
+  updatedAt: 4,
+};
+
+type HookCapture = {
+  ai: ReturnType<typeof useAIState> | null;
+  sessions: AISession[];
+  activeSessionIdMap: Record<string, string | null>;
+};
+
+function ForkHarness({ capture }: { capture: HookCapture }) {
+  capture.ai = useAIState();
+  const store = useAISessionsStore();
+  capture.sessions = store.sessions as AISession[];
+  capture.activeSessionIdMap = store.activeSessionIdMap as Record<string, string | null>;
+  return null;
+}
+
+async function setupAiState(sessions: AISession[]) {
+  const dom = new JSDOM('<!doctype html><html><body></body></html>', {
+    url: 'http://localhost',
+  });
+  Object.defineProperty(globalThis, 'window', { configurable: true, value: dom.window });
+  Object.defineProperty(globalThis, 'document', { configurable: true, value: dom.window.document });
+  Object.defineProperty(globalThis, 'localStorage', { configurable: true, value: dom.window.localStorage });
+  Object.defineProperty(globalThis, 'CustomEvent', { configurable: true, value: dom.window.CustomEvent });
+  Object.defineProperty(globalThis, 'Event', { configurable: true, value: dom.window.Event });
+  Object.defineProperty(globalThis, 'IS_REACT_ACT_ENVIRONMENT', { configurable: true, value: true });
+
+  setLatestAISessionsSnapshot(sessions);
+  dom.window.localStorage.setItem('netcatty_ai_sessions_v1', JSON.stringify(sessions));
+
+  const container = document.createElement('div');
+  document.body.appendChild(container);
+  const root = createRoot(container);
+  const capture: HookCapture = { ai: null, sessions: [], activeSessionIdMap: {} };
+  await act(async () => {
+    root.render(React.createElement(ForkHarness, { capture }));
+  });
+  return { dom, container, root, capture };
+}
+
+test('fork retains the completed prefix, replay metadata, and source-owned outputs', async () => {
+  const runtime = getAgentRuntime();
+  const outputStore = runtime.getToolOutputStore('chat-source');
+  const handle = outputStore.store({ chatSessionId: 'chat-source', capabilityId: 'terminal.exec', content: 'saved output' });
+  runtime.getSessionStateStore().updateFromToolResult('chat-source', 'terminal_start',
+    { sessionId: 'terminal-a', command: 'running-command' },
+    JSON.stringify({ jobId: 'source-job', status: 'running', nextOffset: 7 }), false);
+  const source = structuredClone(SOURCE_SESSION);
+  source.externalSessionId = 'original-provider-thread';
+  source.messages[1].content = `Preview handleId=${handle.id}`;
+  source.messages[1].providerContinuation = { reasoningParts: [{ text: 'checked', providerOptions: { anthropic: { signature: 'signed-thinking' } } }] };
+  const { dom, container, root, capture } = await setupAiState([source]);
+  let branch: AISession | null = null;
+  await act(async () => { branch = await capture.ai!.forkSessionFromMessage(source.id, 'assistant-1', { type: 'terminal', targetId: 'reconnected' }); });
+  assert.ok(branch);
+  assert.notEqual(branch!.id, source.id);
+  assert.equal(branch!.externalSessionId, undefined);
+  assert.deepEqual(branch!.messages[1].providerContinuation, source.messages[1].providerContinuation);
+  assert.match(branch!.messages[1].content, /Preview/);
+  assert.doesNotMatch(branch!.messages[1].content, /handleId=/);
+  assert.deepEqual(branch!.scope, { type: 'terminal', targetId: 'reconnected', hostIds: undefined });
+  assert.equal(capture.activeSessionIdMap['terminal:reconnected'], branch!.id);
+  assert.deepEqual({ ...capture.sessions.find(item => item.id === source.id), updatedAt: source.updatedAt }, source);
+  assert.equal(outputStore.read({ handleId: handle.id }, branch!.id), null);
+  assert.equal(outputStore.read({ handleId: handle.id }, source.id), 'saved output');
+  assert.deepEqual(runtime.getSessionStateStore().get(branch!.id).activeJobs, {});
+  assert.ok(runtime.getSessionStateStore().get(source.id).activeJobs['source-job']);
+  runtime.getSessionStateStore().clear(source.id);
+  outputStore.prune(source.id);
+  await act(async () => root.unmount()); container.remove(); dom.window.close();
+});
+
+test('fork rejects an incomplete boundary without adding a chat', async () => {
+  const source = structuredClone(SOURCE_SESSION);
+  source.messages[1].executionStatus = 'failed';
+  const { dom, container, root, capture } = await setupAiState([source]);
+  let result: unknown;
+  await act(async () => { result = await capture.ai!.forkSessionFromMessage(source.id, 'assistant-1'); });
+  assert.equal(result, null);
+  assert.equal(capture.sessions.length, 1);
+  await act(async () => root.unmount()); container.remove(); dom.window.close();
+});
+
+for (const newerCount of [49, 50]) {
+  test(`fork preserves the original on reload with ${newerCount} newer chats`, async () => {
+    const newer = Array.from({ length: newerCount }, (_, index) => ({ ...structuredClone(SOURCE_SESSION), id: `history-${index}`, updatedAt: 100 + index }));
+    const { dom, container, root, capture } = await setupAiState([...newer, SOURCE_SESSION]);
+    let branch: AISession | null = null;
+    await act(async () => { branch = await capture.ai!.forkSessionFromMessage(SOURCE_SESSION.id, 'assistant-1'); });
+    assert.ok(branch);
+    const saved: AISession[] = JSON.parse(dom.window.localStorage.getItem('netcatty_ai_sessions_v1')!);
+    assert.equal(saved.length, 50);
+    assert.deepEqual(saved.find(item => item.id === SOURCE_SESSION.id)?.messages, SOURCE_SESSION.messages);
+    assert.deepEqual(saved.find(item => item.id === branch!.id)?.messages, SOURCE_SESSION.messages.slice(0, 2));
+    await act(async () => root.unmount()); container.remove(); dom.window.close();
+    const reloaded = await setupAiState(saved);
+    assert.equal(reloaded.capture.sessions.find(item => item.id === SOURCE_SESSION.id)?.messages.length, 4);
+    assert.equal(reloaded.capture.sessions.find(item => item.id === branch!.id)?.messages.length, 2);
+    await act(async () => reloaded.root.unmount()); reloaded.container.remove(); reloaded.dom.window.close();
+  });
+}

application/state/useAIState.ts

@@ -55,6 +55,7 @@ import {
 import { convertFilesToUploads } from './useFileUpload';
 import { removeProviderReferences } from './aiProviderCleanup';
 import { publishAISessionsSnapshot } from './aiSessionsStore';
+import { planSessionFork } from '../../domain/aiSessionFork';
 import {
   AI_STATE_CHANGED_DRAFTS_BY_SCOPE,
   AI_STATE_CHANGED_PANEL_VIEW_BY_SCOPE,
@@ -86,6 +87,11 @@ import {
   retargetWorkspaceActiveChatAfterMemberLoss,
   seedWorkspaceAIActiveSessionFromMembers,
 } from '../../domain/workspaceAiScopeHandoff';
+import {
+  buildUndoLastTurnBranch,
+  type UndoLastTurnRestoredDraft,
+} from '../../domain/aiUndoLastTurn';
+
 
 function providerPatchIsNoop(
   current: ProviderConfig,
@@ -675,6 +681,57 @@ export function useAIState() {
     };
   }, [persistSessions]);
 
+  // "Fork from here": copy the conversation up to a completed assistant
+  // response into a new session and make it the scope's active chat. The
+  // original session stays untouched in history. Pure boundary validation and
+  // plan building live in domain/aiSessionFork; the fork has no original
+  // external session id or pending-turn state. Per-message replay metadata is
+  // preserved; output handles and running jobs remain owned by the source.
+  // Null is returned when the boundary is not forkable.
+  // `viewingScope` is the panel scope the fork was requested from; the branch
+  // is created there so the fork is active and visible in the very scope that
+  // is viewing it, even when the source session carries a stale scope (e.g. a
+  // terminal chat resumed in a reconnected terminal or a merged workspace).
+  const forkSessionFromMessage = useCallback(async (
+    sessionId: string,
+    messageId: string,
+    viewingScope?: Pick<AISessionScope, 'type' | 'targetId'>,
+  ): Promise<AISession | null> => {
+    const source = sessionsRef.current.find(s => s.id === sessionId);
+    if (!source) return null;
+    const plan = planSessionFork(source, messageId);
+    if (!plan.ok) return null;
+    const now = Date.now();
+    const fork: AISession = {
+      id: `ai_${now}_${Math.random().toString(36).slice(2, 8)}`,
+      title: plan.title,
+      agentId: source.agentId,
+      scope: {
+        ...source.scope,
+        // Host membership stays with the source (the messages were produced
+        // there); the scope the fork belongs to is the viewing scope.
+        ...(viewingScope ? { type: viewingScope.type, targetId: viewingScope.targetId } : {}),
+        hostIds: source.scope.hostIds ? [...source.scope.hostIds] : undefined,
+      },
+      messages: plan.messages,
+      createdAt: now,
+      updatedAt: now,
+    };
+    if (plan.contextCompaction) {
+      fork.contextCompaction = plan.contextCompaction;
+    }
+    setSessionsRaw(prev => {
+      // Keep the source alongside its branch within the existing history limit.
+      const next = [fork, { ...source, updatedAt: now }, ...prev.filter(session => session.id !== source.id)];
+      setLatestAISessionsSnapshot(next);
+      persistSessions(next);
+      return next;
+    });
+    const scopeKey = `${fork.scope.type}:${fork.scope.targetId ?? ''}`;
+    setActiveSessionId(scopeKey, fork.id);
+    return fork;
+  }, [persistSessions, setActiveSessionId]);
+
   const createSession = useCallback((scope: AISessionScope, agentId?: string): AISession => {
     const now = Date.now();
     const session: AISession = {
@@ -697,6 +754,32 @@ export function useAIState() {
     return session;
   }, [defaultAgentId, persistSessions, setActiveSessionId]);
 
+  // Non-destructive "undo last turn": branch the session at the boundary
+  // before the latest user message and keep the original in history intact.
+  // Returns the new branch id plus the undone user message for the composer.
+  const undoLastTurnInSession = useCallback(async (sessionId: string): Promise<{
+    sessionId: string;
+    restored: UndoLastTurnRestoredDraft;
+  } | null> => {
+    const nextId = `ai_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`;
+    const source = sessionsRef.current.find(s => s.id === sessionId);
+    if (!source) return null;
+    const result = buildUndoLastTurnBranch(source, { newId: nextId, now: Date.now() });
+    if (!result) return null;
+
+    const branched = result.session;
+    setSessionsRaw(prev => {
+      // Keep both recently used chats within the existing history limit.
+      const next = [branched, { ...source, updatedAt: branched.updatedAt }, ...prev.filter(session => session.id !== source.id)];
+      setLatestAISessionsSnapshot(next);
+      persistSessions(next);
+      return next;
+    });
+    const scopeKey = `${branched.scope.type}:${branched.scope.targetId ?? ''}`;
+    setActiveSessionId(scopeKey, branched.id);
+    return { sessionId: branched.id, restored: result.restored };
+  }, [persistSessions, setActiveSessionId]);
+
   const deleteSession = useCallback((sessionId: string, scopeKey?: string) => {
     cleanupDeletedAIChatSessions([sessionId]);
     if (persistTimerRef.current) {
@@ -1275,6 +1358,7 @@ export function useAIState() {
     addDraftFiles,
     removeDraftFile,
     createSession,
+    undoLastTurnInSession,
     deleteSession,
     deleteSessionsByTarget,
     updateSessionTitle,
@@ -1287,6 +1371,7 @@ export function useAIState() {
     seedWorkspaceActiveSessionFromMembers,
     handoffDissolvedWorkspaceScope,
     retargetWorkspaceActiveChatForMemberLoss,
+    forkSessionFromMessage,
   }), [
     providers,
     setProviders,
@@ -1335,6 +1420,7 @@ export function useAIState() {
     addDraftFiles,
     removeDraftFile,
     createSession,
+    undoLastTurnInSession,
     deleteSession,
     deleteSessionsByTarget,
     updateSessionTitle,
@@ -1347,5 +1433,6 @@ export function useAIState() {
     seedWorkspaceActiveSessionFromMembers,
     handoffDissolvedWorkspaceScope,
     retargetWorkspaceActiveChatForMemberLoss,
+    forkSessionFromMessage,
   ]);
 }

application/state/useAIState.undoLastTurn.test.ts

@@ -0,0 +1,194 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import React, { act } from 'react';
+import { createRoot } from 'react-dom/client';
+import { JSDOM } from 'jsdom';
+
+import type { AISession, UploadedFile } from '../../infrastructure/ai/types.ts';
+import { getAgentRuntime } from '../../infrastructure/ai/harness/globalAgentRuntime.ts';
+import { useAIState } from './useAIState.ts';
+import { useAISessionsStore } from './aiSessionsStore.ts';
+import { setLatestAISessionsSnapshot } from './aiStateSnapshots.ts';
+
+const SCOPE_KEY = 'terminal:terminal-a';
+
+const SOURCE_SESSION: AISession = {
+  id: 'chat-source',
+  title: 'Undo source',
+  agentId: 'catty',
+  scope: { type: 'terminal', targetId: 'terminal-a' },
+  messages: [
+    { id: 'user-1', role: 'user', content: 'first prompt', timestamp: 1 },
+    { id: 'assistant-1', role: 'assistant', content: 'first answer', timestamp: 2 },
+    {
+      id: 'user-2',
+      role: 'user',
+      content: 'bad last prompt',
+      timestamp: 3,
+      attachments: [
+        { base64Data: 'QUJD', mediaType: 'text/plain', filename: 'note.txt', lineCount: 2 },
+      ],
+    },
+    { id: 'assistant-2', role: 'assistant', content: 'bad answer', timestamp: 4 },
+  ],
+  createdAt: 1,
+  updatedAt: 4,
+};
+
+type HookCapture = {
+  ai: ReturnType<typeof useAIState> | null;
+  sessions: AISession[];
+  activeSessionIdMap: Record<string, string | null>;
+};
+
+function UndoHarness({ capture }: { capture: HookCapture }) {
+  capture.ai = useAIState();
+  const store = useAISessionsStore();
+  capture.sessions = store.sessions as AISession[];
+  capture.activeSessionIdMap = store.activeSessionIdMap as Record<string, string | null>;
+  return null;
+}
+
+async function setupAiState(sessions: AISession[]) {
+  const dom = new JSDOM('<!doctype html><html><body></body></html>', {
+    url: 'http://localhost',
+  });
+  Object.defineProperty(globalThis, 'window', { configurable: true, value: dom.window });
+  Object.defineProperty(globalThis, 'document', { configurable: true, value: dom.window.document });
+  Object.defineProperty(globalThis, 'localStorage', { configurable: true, value: dom.window.localStorage });
+  Object.defineProperty(globalThis, 'CustomEvent', { configurable: true, value: dom.window.CustomEvent });
+  Object.defineProperty(globalThis, 'Event', { configurable: true, value: dom.window.Event });
+  Object.defineProperty(globalThis, 'IS_REACT_ACT_ENVIRONMENT', { configurable: true, value: true });
+
+  setLatestAISessionsSnapshot(sessions);
+  dom.window.localStorage.setItem('netcatty_ai_sessions_v1', JSON.stringify(sessions));
+
+  const container = document.createElement('div');
+  document.body.appendChild(container);
+  const root = createRoot(container);
+  const capture: HookCapture = { ai: null, sessions: [], activeSessionIdMap: {} };
+  await act(async () => {
+    root.render(React.createElement(UndoHarness, { capture }));
+  });
+  return { dom, container, root, capture };
+}
+
+test('undoLastTurnInSession branches and restores the last user turn', async () => {
+  const { dom, container, root, capture } = await setupAiState([SOURCE_SESSION]);
+  assert.ok(capture.ai);
+
+  let result: Awaited<ReturnType<typeof runUndo>> | null = null;
+  async function runUndo() {
+    return capture.ai!.undoLastTurnInSession('chat-source');
+  }
+
+  await act(async () => {
+    result = await runUndo();
+  });
+
+  assert.ok(result);
+  assert.notEqual(result!.sessionId, 'chat-source');
+
+  const sessions = capture.sessions;
+  const branch = sessions.find((session) => session.id === result!.sessionId);
+  assert.ok(branch);
+  // Branch keeps the conversation up to the boundary before the last turn.
+  assert.deepEqual(
+    branch!.messages.map((message) => message.content),
+    ['first prompt', 'first answer'],
+  );
+  // Original session stays intact (non-destructive).
+  const original = sessions.find((session) => session.id === 'chat-source');
+  assert.equal(original?.messages.length, 4);
+  // Branch becomes the active session for the scope.
+  assert.equal(capture.activeSessionIdMap[SCOPE_KEY], result!.sessionId);
+
+  const attachments = result!.restored.attachments as UploadedFile[];
+  assert.equal(result!.restored.text, 'bad last prompt');
+  assert.equal(attachments.length, 1);
+  assert.equal(attachments[0].filename, 'note.txt');
+  assert.equal(attachments[0].dataUrl, 'data:text/plain;base64,QUJD');
+
+  await act(async () => root.unmount());
+  container.remove();
+  dom.window.close();
+});
+
+test('undoLastTurnInSession returns null when there is nothing to undo', async () => {
+  const emptySession: AISession = {
+    ...SOURCE_SESSION,
+    id: 'chat-empty',
+    messages: [],
+  };
+  const { dom, container, root, capture } = await setupAiState([emptySession]);
+  assert.ok(capture.ai);
+
+  let result: unknown;
+  await act(async () => {
+    result = await capture.ai!.undoLastTurnInSession('chat-empty');
+  });
+  assert.equal(result, null);
+
+  await act(async () => root.unmount());
+  container.remove();
+  dom.window.close();
+});
+
+test('undo copies chat only, preserving original outputs and job ownership', async () => {
+  const runtime = getAgentRuntime();
+  const outputStore = runtime.getToolOutputStore('chat-source');
+  const handle = outputStore.store({
+    chatSessionId: 'chat-source', capabilityId: 'terminal.exec', content: 'original saved output',
+  });
+  const stateStore = runtime.getSessionStateStore();
+  stateStore.updateFromToolResult('chat-source', 'terminal_start',
+    { sessionId: 'terminal-a', command: 'long-running-command' },
+    JSON.stringify({ jobId: 'original-job', status: 'running', nextOffset: 7 }), false);
+  const source = structuredClone(SOURCE_SESSION);
+  source.messages[1].content = `Preview with handleId=${handle.id}`;
+  const { dom, container, root, capture } = await setupAiState([source]);
+  const original = JSON.stringify(source);
+  let result: { sessionId: string } | null = null;
+  await act(async () => { result = await capture.ai!.undoLastTurnInSession(source.id); });
+  assert.ok(result);
+  assert.equal(outputStore.read({ handleId: handle.id }, result!.sessionId), null);
+  assert.equal(outputStore.read({ handleId: handle.id }, source.id), 'original saved output');
+  assert.deepEqual(stateStore.get(result!.sessionId).activeJobs, {});
+  assert.ok(stateStore.get(source.id).activeJobs['original-job']);
+  assert.equal(JSON.stringify({ ...capture.sessions.find(item => item.id === source.id), updatedAt: source.updatedAt }), original);
+  assert.ok(capture.sessions.find(item => item.id === result!.sessionId)!.messages[1].content.includes('Preview'));
+  stateStore.clear(source.id);
+  outputStore.prune(source.id);
+  await act(async () => root.unmount());
+  container.remove(); dom.window.close();
+});
+
+for (const newerCount of [49, 50]) {
+  test(`undo retains an old source and its branch after reload with ${newerCount} newer chats`, async () => {
+    const newer = Array.from({ length: newerCount }, (_, index) => ({
+      ...structuredClone(SOURCE_SESSION), id: `history-${index}`, updatedAt: 100 + index,
+    }));
+    const { dom, container, root, capture } = await setupAiState([...newer, SOURCE_SESSION]);
+    let branchId: string | undefined;
+    await act(async () => {
+      branchId = (await capture.ai!.undoLastTurnInSession(SOURCE_SESSION.id))?.sessionId;
+    });
+    assert.ok(branchId);
+    const saved: AISession[] = JSON.parse(dom.window.localStorage.getItem('netcatty_ai_sessions_v1')!);
+    assert.equal(saved.length, 50);
+    const original = saved.find(item => item.id === SOURCE_SESSION.id);
+    assert.ok(original, 'the original must survive updatedAt-based history pruning');
+    assert.deepEqual({ ...original, updatedAt: SOURCE_SESSION.updatedAt }, SOURCE_SESSION);
+    assert.deepEqual(saved.find(item => item.id === branchId)?.messages, SOURCE_SESSION.messages.slice(0, 2));
+    assert.ok(original.updatedAt >= newer.at(-1)!.updatedAt);
+    await act(async () => root.unmount());
+    container.remove(); dom.window.close();
+
+    // Remount the actual hook from the persisted records, as on app reload.
+    const reloaded = await setupAiState(saved);
+    assert.deepEqual(reloaded.capture.sessions.find(item => item.id === SOURCE_SESSION.id)?.messages, SOURCE_SESSION.messages);
+    assert.deepEqual(reloaded.capture.sessions.find(item => item.id === branchId)?.messages, SOURCE_SESSION.messages.slice(0, 2));
+    await act(async () => reloaded.root.unmount());
+    reloaded.container.remove(); reloaded.dom.window.close();
+  });
+}

application/state/useHostOpenSessionReuse.test.ts

@@ -0,0 +1,383 @@
+import assert from 'node:assert/strict';
+import { test } from 'node:test';
+import React from 'react';
+import { act, create, type ReactTestRenderer } from 'react-test-renderer';
+import type { GroupConfig, Host, Identity, SSHKey, TerminalSession } from '../../domain/models';
+import { updateRestoredSessionStatusState } from './sessionRestoreState';
+import { resolveEffectiveTerminalHost, resolveTerminalSessionHost } from '../../domain/terminalHostResolution';
+import { createHostTerminalSession } from './sessionFactories';
+import { resolveHostDefaultLocalShell } from '../../domain/localShellHost';
+import { useHostOpenSessionReuse } from './useHostOpenSessionReuse';
+import { resolveShellSetting } from '../../lib/useDiscoveredShells';
+
+(globalThis as { IS_REACT_ACT_ENVIRONMENT?: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
+const effective = (host: Host) => host;
+const host = (extra: Partial<Host> = {}): Host => ({
+  id: 'host', hostname: 'original.invalid', username: 'user', label: 'Original', os: 'linux', tags: [], protocol: 'ssh', ...extra,
+});
+
+async function harness(initial: Host, extra: { hosts?: Host[]; keys?: SSHKey[]; identities?: Identity[]; sessions?: TerminalSession[]; resolveEffectiveHost?: (host: Host) => Host } = {}) {
+  let hosts = [initial, ...(extra.hosts ?? [])];
+  let keys = extra.keys ?? [];
+  let identities = extra.identities ?? [];
+  let sessions: TerminalSession[] = extra.sessions ?? [{ ...createHostTerminalSession('tab', initial), status: 'connected' }];
+  let find: ReturnType<typeof useHostOpenSessionReuse>;
+  function Harness() {
+    find = useHostOpenSessionReuse({ sessions, hosts, keys, identities, resolveEffectiveHost: extra.resolveEffectiveHost ?? effective });
+    return null;
+  }
+  let renderer: ReactTestRenderer;
+  await act(async () => { renderer = create(React.createElement(Harness)); });
+  return {
+    find: () => find(initial.id),
+    async update(input: { host?: Host; hosts?: Host[]; keys?: SSHKey[]; identities?: Identity[]; sessions?: TerminalSession[] }) {
+      hosts = input.hosts ?? (input.host ? [input.host, ...hosts.slice(1)] : hosts);
+      keys = input.keys ?? keys;
+      identities = input.identities ?? identities;
+      sessions = input.sessions ?? sessions;
+      await act(async () => renderer.update(React.createElement(Harness)));
+    },
+    close: () => act(async () => renderer.unmount()),
+  };
+}
+
+for (const [field, value] of [
+  ['hostname', 'replacement.invalid'], ['username', 'other-user'], ['port', 2222],
+  ['protocol', 'telnet'], ['password', 'new-password'], ['authMethod', 'key'],
+  ['hostChain', { hostIds: ['jump'] }],
+  ['proxyConfig', { type: 'socks5', host: 'proxy.invalid', port: 1080 }],
+] as const) {
+  test(`a saved ${field} edit cannot reuse the old tab`, async (t) => {
+    const original = host({ password: 'old-password', authMethod: 'password' });
+    const api = await harness(original, { hosts: [host({ id: 'jump', hostname: 'jump.invalid' })] });
+    t.after(api.close);
+    assert.equal((await api.find())?.sessionId, 'tab');
+    await api.update({ host: { ...original, [field]: value } });
+    assert.equal(await api.find(), undefined);
+  });
+}
+
+test('renaming the target and jump host keeps the same tab eligible', async (t) => {
+  const original = host({ hostChain: { hostIds: ['jump'] } });
+  const jump = host({ id: 'jump', hostname: 'jump.invalid' });
+  const api = await harness(original, { hosts: [jump] });
+  t.after(api.close);
+  await api.update({ hosts: [{ ...original, label: 'Renamed', fontSize: 16, notes: 'Updated note' }, { ...jump, label: 'Renamed jump' }] });
+  assert.equal((await api.find())?.sessionId, 'tab');
+});
+
+test('changing a jump endpoint or its password rejects the original connection', async (t) => {
+  const original = host({ hostChain: { hostIds: ['jump'] } });
+  const jump = host({ id: 'jump', hostname: 'jump.invalid', password: 'old' });
+  const api = await harness(original, { hosts: [jump] });
+  t.after(api.close);
+  for (const changed of [{ ...jump, hostname: 'new-jump.invalid' }, { ...jump, password: 'new' }]) {
+    await api.update({ hosts: [original, changed] });
+    assert.equal(await api.find(), undefined);
+  }
+});
+
+test('rotating a referenced identity or key keeps stable IDs from masking auth changes', async (t) => {
+  const identity: Identity = { id: 'identity', label: 'Login', username: 'user', password: 'old', authMethod: 'password', created: 0 };
+  const original = host({ identityId: identity.id });
+  const api = await harness(original, { identities: [identity] });
+  t.after(api.close);
+  assert.equal((await api.find())?.sessionId, 'tab');
+  await api.update({ identities: [{ ...identity, password: 'rotated' }] });
+  assert.equal(await api.find(), undefined);
+  const key: SSHKey = { id: 'key', label: 'Key', type: 'ED25519', privateKey: 'old-key', source: 'generated', category: 'key', created: 0 };
+  const keyHost = host({ identityFileId: key.id, authMethod: 'key' });
+  const keyApi = await harness(keyHost, { keys: [key] });
+  t.after(keyApi.close);
+  assert.equal((await keyApi.find())?.sessionId, 'tab');
+  await keyApi.update({ keys: [{ ...key, privateKey: 'rotated-key' }] });
+  assert.equal(await keyApi.find(), undefined);
+});
+
+for (const [field, value] of [
+  ['baudRate', 19200], ['dataBits', 7], ['stopBits', 2], ['parity', 'even'], ['flowControl', 'rts/cts'],
+] as const) {
+  test(`a serial ${field} edit must not reuse the opening parameters`, async (t) => {
+    const original = host({ protocol: 'serial', hostname: '/dev/tty.test', username: '', serialConfig: { path: '/dev/tty.test', baudRate: 9600, dataBits: 8, stopBits: 1, parity: 'none', flowControl: 'none' } });
+    const api = await harness(original);
+    t.after(api.close);
+    assert.equal((await api.find())?.sessionId, 'tab');
+    await api.update({ host: { ...original, serialConfig: { ...original.serialConfig!, [field]: value } } });
+    assert.equal(await api.find(), undefined);
+  });
+}
+
+test('unchanged legacy serial defaults still match their opening snapshot', async (t) => {
+  const original = host({ protocol: 'serial', hostname: '/dev/tty.test', username: '', port: 9600 });
+  const api = await harness(original);
+  t.after(api.close);
+  assert.equal((await api.find())?.sessionId, 'tab');
+});
+
+test('the captured serial settings come from the opening session even if the vault was already edited', async (t) => {
+  const original = host({ protocol: 'serial', hostname: '/dev/tty.test', username: '', serialConfig: { path: '/dev/tty.test', baudRate: 9600 } });
+  const session: TerminalSession = { ...createHostTerminalSession('tab', original), status: 'connected' };
+  const api = await harness({ ...original, serialConfig: { ...original.serialConfig!, baudRate: 19200 } }, { sessions: [session] });
+  t.after(api.close);
+  assert.equal(await api.find(), undefined);
+});
+
+for (const changedField of ['configuration', 'credentialId'] as const) {
+  test(`a restored plugin tab keeps its opening ${changedField} after manual reconnect`, async (t) => {
+    const providerId = 'com.example.transport.connection';
+    const original = host({ protocol: `plugin:${providerId}`, pluginConnection: { providerId, configuration: { endpoint: 'original.invalid' }, credentialId: 'original-credential-reference' } });
+    const edited = { ...original, pluginConnection: { ...original.pluginConnection!, [changedField]: changedField === 'configuration' ? { endpoint: 'replacement.invalid' } : 'replacement-credential-reference' } };
+    const restored: TerminalSession = { ...createHostTerminalSession('tab', original), status: 'disconnected', restoreState: 'restored-disconnected' };
+    const api = await harness(edited, { sessions: [restored] });
+    t.after(api.close);
+    assert.equal(await api.find(), undefined);
+    const reconnecting = updateRestoredSessionStatusState([restored], restored.id, 'connecting');
+    const actual = resolveTerminalSessionHost({ session: reconnecting[0], hosts: [edited], groupConfigs: [], proxyProfiles: [], localOs: 'linux' });
+    assert.deepEqual(actual.pluginConnection, original.pluginConnection, 'the real terminal resolver uses the restored opening configuration');
+    await api.update({ sessions: reconnecting });
+    assert.equal(await api.find(), undefined, 'host_open must not call that old transport the edited vault connection');
+  });
+}
+
+test('an unchanged restored plugin configuration can be reused after manual reconnect', async (t) => {
+  const providerId = 'com.example.transport.connection';
+  const original = host({ protocol: `plugin:${providerId}`, pluginConnection: { providerId, configuration: { endpoint: 'original.invalid' } } });
+  const restored: TerminalSession = { ...createHostTerminalSession('tab', original), status: 'disconnected', restoreState: 'restored-disconnected' };
+  const api = await harness({ ...original, label: 'Renamed' }, { sessions: [restored] });
+  t.after(api.close);
+  await api.update({ sessions: updateRestoredSessionStatusState([restored], restored.id, 'connecting') });
+  assert.equal((await api.find())?.sessionId, 'tab');
+});
+
+for (const [field, value] of [
+  ['telnetPort', 2324], ['telnetUsername', 'other-telnet-user'], ['telnetPassword', 'rotated-telnet-password'],
+] as const) {
+  test(`a Telnet ${field} edit cannot reuse the old transport`, async (t) => {
+    const original = host({ protocol: 'telnet', telnetPort: 2323, telnetUsername: 'telnet-user', telnetPassword: 'telnet-password' });
+    const api = await harness(original);
+    t.after(api.close);
+    assert.equal((await api.find())?.sessionId, 'tab');
+    await api.update({ host: { ...original, [field]: value } });
+    assert.equal(await api.find(), undefined);
+  });
+}
+
+test('Telnet identity credential rotation and missing identity reject reuse', async (t) => {
+  const identity: Identity = { id: 'telnet-login', label: 'Telnet login', username: 'telnet-user', password: 'original', authMethod: 'password', created: 0 };
+  const original = host({ protocol: 'telnet', telnetIdentityId: identity.id });
+  const api = await harness(original, { identities: [identity] });
+  t.after(api.close);
+  assert.equal((await api.find())?.sessionId, 'tab');
+  for (const identities of [[{ ...identity, username: 'other-user' }], [{ ...identity, password: 'rotated' }], []]) {
+    await api.update({ identities });
+    assert.equal(await api.find(), undefined);
+  }
+});
+
+test('Telnet explicit empty login does not fall back to SSH login fields', async (t) => {
+  const original = host({ protocol: 'telnet', telnetUsername: '', telnetPassword: '', password: 'ssh-only' });
+  const api = await harness(original);
+  t.after(api.close);
+  assert.equal((await api.find())?.sessionId, 'tab');
+  await api.update({ host: { ...original, label: 'Renamed', username: 'unrelated-ssh-user', password: 'unrelated-ssh-password', identityId: 'missing-ssh-identity', telnetPort: 23 } });
+  assert.equal((await api.find())?.sessionId, 'tab');
+  await api.update({ host: { ...original, telnetUsername: undefined, telnetPassword: undefined } });
+  assert.equal(await api.find(), undefined, 'removing explicit empty overrides enables the actual fallback login');
+});
+
+for (const transport of [{ protocol: 'et' as const }, { protocol: 'ssh' as const, etEnabled: true }]) {
+  test(`changing a jump ET server port rejects the old ${JSON.stringify(transport)} transport`, async (t) => {
+    const original = host({ ...transport, hostChain: { hostIds: ['jump'] } });
+    const jump = host({ id: 'jump', hostname: 'jump.invalid', etPort: 2022 });
+    const api = await harness(original, { hosts: [jump] });
+    t.after(api.close);
+    assert.equal((await api.find())?.sessionId, 'tab');
+    await api.update({ hosts: [original, { ...jump, etPort: 3022 }] });
+    assert.equal(await api.find(), undefined);
+  });
+}
+
+test('serial direct auto-login password is not masked by an unrelated SSH identity', async (t) => {
+  const identity: Identity = { id: 'ssh-login', label: 'SSH login', username: 'ssh-user', password: 'ssh-password', authMethod: 'password', created: 0 };
+  const original = host({ protocol: 'serial', hostname: '/dev/tty.test', username: '', password: 'serial-password', identityId: identity.id });
+  const api = await harness(original, { identities: [identity] });
+  t.after(api.close);
+  assert.equal((await api.find())?.sessionId, 'tab');
+  await api.update({ host: { ...original, password: 'rotated-serial-password' } });
+  assert.equal(await api.find(), undefined);
+});
+
+test('unchanged serial direct username matches the actual auto-login input', async (t) => {
+  const original = host({ protocol: 'serial', hostname: '/dev/tty.test', username: 'serial-user', password: 'serial-password' });
+  const api = await harness(original);
+  t.after(api.close);
+  assert.equal((await api.find())?.sessionId, 'tab');
+  await api.update({ host: { ...original, username: 'other-serial-user' } });
+  assert.equal(await api.find(), undefined);
+});
+
+for (const [field, value] of [
+  ['localShell', '/bin/bash'], ['localShellArgs', ['--norc']], ['localStartDir', '/replacement'],
+] as const) {
+  test(`a saved local ${field} edit cannot reuse the old process`, async (t) => {
+    const original = host({ protocol: 'local', hostname: 'localhost', localShell: '/bin/zsh', localShellArgs: ['-l'], localStartDir: '/original' });
+    const session = { ...createHostTerminalSession('tab', original), status: 'connected', localShell: original.localShell, localShellArgs: original.localShellArgs, localStartDir: original.localStartDir } as TerminalSession;
+    const api = await harness(original, { sessions: [session] });
+    t.after(api.close);
+    assert.equal((await api.find())?.sessionId, 'tab');
+    await api.update({ host: { ...original, [field]: value } });
+    assert.equal(await api.find(), undefined);
+    const alreadyEdited = await harness({ ...original, [field]: value }, { sessions: [session] });
+    t.after(alreadyEdited.close);
+    assert.equal(await alreadyEdited.find(), undefined, 'opening fields come from the actual local session');
+  });
+}
+
+test('local default shell, cwd and empty args match the renderer launch contract', async (t) => {
+  const original = host({ protocol: 'local', hostname: 'localhost' });
+  const api = await harness(original);
+  t.after(api.close);
+  await api.update({ host: { ...original, localShell: '', localStartDir: '', label: 'Renamed' } });
+  assert.equal((await api.find())?.sessionId, 'tab');
+  await api.update({ host: { ...original, localShellArgs: [] } });
+  assert.equal((await api.find())?.sessionId, 'tab', 'the renderer omits empty args so backend login defaults still apply');
+});
+
+for (const [label, proxy] of [
+  ['a missing saved profile', { proxyProfileId: 'missing-profile' }],
+  ['a usable proxy', { proxyConfig: { type: 'socks5', host: 'proxy.invalid', port: 1080 } }],
+  ['a missing proxy identity', { proxyConfig: { type: 'socks5', host: '', port: 0, identityId: 'missing-identity' } }],
+  ['an incomplete proxy identity', { proxyConfig: { type: 'socks5', host: '', port: 0, identityId: 'incomplete-identity' } }],
+] as const) {
+  test(`Telnet adding ${label} cannot bypass actual starter rejection through reuse`, async (t) => {
+    const original = host({ protocol: 'telnet' });
+    const api = await harness(original, { identities: [{ id: 'incomplete-identity', label: 'Incomplete', username: 'proxy-user', authMethod: 'password', created: 0 }] });
+    t.after(api.close);
+    assert.equal((await api.find())?.sessionId, 'tab');
+    await api.update({ host: { ...original, ...proxy } });
+    assert.equal(await api.find(), undefined);
+    await api.update({ host: { ...original, label: 'Renamed without a proxy' } });
+    assert.equal((await api.find())?.sessionId, 'tab');
+  });
+}
+
+test('Telnet inheriting a proxy profile cannot reuse its previous direct session', async (t) => {
+  const original = host({ protocol: 'telnet', group: 'prod/web' });
+  const groupConfigs: GroupConfig[] = [];
+  const proxyProfiles = [{ id: 'group-proxy', label: 'Proxy', createdAt: 0, config: { type: 'socks5' as const, host: 'proxy.invalid', port: 1080 } }];
+  const resolveEffectiveHost = (candidate: Host) => resolveEffectiveTerminalHost({ host: candidate, groupConfigs, proxyProfiles });
+  const api = await harness(original, { resolveEffectiveHost });
+  t.after(api.close);
+  assert.equal((await api.find())?.sessionId, 'tab');
+  groupConfigs.push({ path: 'prod', proxyProfileId: 'group-proxy' });
+  assert.equal(resolveEffectiveHost(original).proxyConfig?.host, 'proxy.invalid');
+  await api.update({ host: { ...original } });
+  assert.equal(await api.find(), undefined);
+});
+
+for (const owner of ['saved', 'global'] as const) {
+  for (const [field, changed] of [
+    ['localShell', '/bin/zsh'], ['localShellArgs', ['--norc']], ['localStartDir', '/project-b'],
+  ] as const) {
+    test(`local launch snapshot survives ${owner} ${field} edits and unchanged defaults reuse`, async (t) => {
+      const settings = { localShell: '/bin/bash', localShellArgs: undefined as string[] | undefined, localStartDir: '/project-a' };
+      const original = host({ protocol: 'local', hostname: 'localhost', ...(owner === 'saved' ? settings : {}) });
+      const context = {
+        terminalSettings: settings,
+        resolveShellSetting: (command: string, _shells: DiscoveredShell[], args?: string[]) => ({ command, args }),
+      };
+      const resolveEffectiveHost = (candidate: Host) => resolveHostDefaultLocalShell(candidate, context);
+      const launched = { ...createHostTerminalSession('launched', resolveEffectiveHost(original)), status: 'connected' as const };
+      const api = await harness(original, { sessions: [launched], resolveEffectiveHost });
+      t.after(api.close);
+      assert.equal((await api.find())?.sessionId, launched.id, 'undefined settings args and [] snapshot launch identically');
+      const edited = owner === 'saved' ? { ...original, [field]: changed } : original;
+      if (owner === 'global') Object.assign(settings, { [field]: changed });
+      await api.update({ host: edited });
+      assert.equal(await api.find(), undefined, 'an edited launch must not return the old process');
+      const copy = resolveTerminalSessionHost({ session: launched, hosts: [edited], groupConfigs: [], proxyProfiles: [], localOs: 'linux', defaultLocalShell: context });
+      assert.equal(copy.localShell, '/bin/bash');
+      assert.deepEqual(copy.localShellArgs, []);
+      assert.equal(copy.localStartDir, '/project-a');
+    });
+  }
+}
+
+test('home and backend-default snapshots do not inherit later global or saved settings', async (t) => {
+  const original = host({ protocol: 'local', hostname: 'localhost' });
+  const settings: { localShell?: string; localStartDir?: string } = {};
+  const context = { terminalSettings: settings, resolveShellSetting: (command: string) => command ? { command } : null };
+  const resolveEffectiveHost = (candidate: Host) => resolveHostDefaultLocalShell(candidate, context);
+  const launched = { ...createHostTerminalSession('home-default', resolveEffectiveHost(original)), status: 'connected' as const };
+  assert.equal(launched.localShell, '');
+  assert.equal(launched.localStartDir, '~');
+  const api = await harness(original, { sessions: [launched], resolveEffectiveHost });
+  t.after(api.close);
+  assert.equal((await api.find())?.sessionId, launched.id);
+  Object.assign(settings, { localShell: '/bin/bash', localStartDir: '/new-global' });
+  const edited = { ...original, localShell: '/bin/zsh', localStartDir: '/new-saved' };
+  await api.update({ host: edited });
+  assert.equal(await api.find(), undefined);
+  const copied = resolveTerminalSessionHost({ session: launched, hosts: [edited], groupConfigs: [], proxyProfiles: [], localOs: 'linux', defaultLocalShell: context });
+  assert.equal(copied.localShell, '', 'empty captured executable still requests backend default');
+  assert.equal(copied.localStartDir, '~', 'home remains home after a new global directory');
+});
+
+test('saved discovery IDs resolve before snapshot while backend default stays independent of discovery', async (t) => {
+  const saved = host({ protocol: 'local', hostname: 'localhost', localShell: 'bash' });
+  const context = {
+    discoveredShells: [{ id: 'bash', name: 'Bash', command: '/bin/bash', args: ['-l'], icon: 'bash', isDefault: true }],
+    resolveShellSetting: (command: string) => command === 'bash' ? { command: '/bin/bash', args: ['-l'] } : null,
+  };
+  const resolveEffectiveHost = (candidate: Host) => resolveHostDefaultLocalShell(candidate, context);
+  const launched = { ...createHostTerminalSession('discovered', resolveEffectiveHost(saved)), status: 'connected' as const };
+  assert.equal(launched.localShell, '/bin/bash');
+  const api = await harness(saved, { sessions: [launched], resolveEffectiveHost });
+  t.after(api.close);
+  assert.equal((await api.find())?.sessionId, launched.id);
+  const defaultLaunch = resolveEffectiveHost({ ...saved, localShell: undefined });
+  assert.equal(defaultLaunch.localShell, '');
+  assert.equal(defaultLaunch.localShellArgs, undefined);
+});
+
+for (const discovered of [
+  { id: 'bin-bash', name: 'Bash', command: '/bin/bash', args: ['-l'], icon: 'bash' },
+  { id: 'wsl-ubuntu', name: 'Ubuntu', command: 'C:\\Windows\\System32\\wsl.exe', args: ['-d', 'Ubuntu'], icon: 'ubuntu' },
+]) {
+  for (const owner of ['saved', 'global'] as const) {
+    test(`cold ${owner} ${discovered.id} reuses after discovery without masking edits`, async (t) => {
+      const settings = { localShell: discovered.id, localStartDir: '/project-a' };
+      const original = host({ protocol: 'local', hostname: 'localhost', ...(owner === 'saved' ? settings : {}) });
+      const context = { terminalSettings: settings, discoveredShells: [] as DiscoveredShell[], resolveShellSetting };
+      const resolveEffectiveHost = (candidate: Host) => resolveHostDefaultLocalShell(candidate, context);
+      const launched = { ...createHostTerminalSession('cold', resolveEffectiveHost(original)), status: 'connected' as const };
+      assert.equal(launched.localShell, discovered.id);
+      const api = await harness(original, { sessions: [launched], resolveEffectiveHost });
+      t.after(api.close);
+      assert.equal((await api.find())?.sessionId, launched.id);
+      context.discoveredShells = [discovered];
+      await api.update({ host: { ...original } });
+      assert.equal((await api.find())?.sessionId, launched.id, 'discovery resolves the same executable and default arguments');
+      const edited = { ...original, localShell: discovered.command, localShellArgs: ['--edited'], localStartDir: '/project-b' };
+      await api.update({ host: edited });
+      assert.equal(await api.find(), undefined, 'a real path/argument/directory edit still opens a new session');
+      const copy = resolveTerminalSessionHost({ session: launched, hosts: [edited], groupConfigs: [], proxyProfiles: [], localOs: 'linux', defaultLocalShell: context });
+      assert.equal(copy.localShell, discovered.id);
+      assert.deepEqual(copy.localShellArgs, []);
+      assert.equal(copy.localStartDir, '/project-a');
+    });
+  }
+}
+
+test('discovery does not replace an explicit executable or its custom arguments with an alias', async (t) => {
+  const original = host({ protocol: 'local', hostname: 'localhost', localShell: '/bin/bash', localShellArgs: ['--norc'] });
+  const context = { discoveredShells: [] as DiscoveredShell[], resolveShellSetting };
+  const resolveEffectiveHost = (candidate: Host) => resolveHostDefaultLocalShell(candidate, context);
+  const api = await harness(original, { resolveEffectiveHost });
+  t.after(api.close);
+  context.discoveredShells = [{ id: 'bin-bash', name: 'Bash', command: '/bin/bash', args: ['-l'], icon: 'bash' }];
+  await api.update({ host: { ...original } });
+  assert.equal((await api.find())?.sessionId, 'tab');
+  await api.update({ host: { ...original, localShell: 'bin-bash', localShellArgs: undefined } });
+  assert.equal(await api.find(), undefined, 'selecting discovered login defaults changes the actual launch');
+});

application/state/useHostOpenSessionReuse.ts

@@ -0,0 +1,149 @@
+import { useCallback, useLayoutEffect, useRef } from 'react';
+import type { Host, Identity, SSHKey, TerminalSession } from '../../domain/models';
+import { findReusableHostSession } from '../../domain/hostOpenSession';
+import { resolveTelnetPassword, resolveTelnetPort, resolveTelnetUsername } from '../../domain/host';
+import { isEncryptedCredentialPlaceholder, sanitizeCredentialValue } from '../../domain/credentials';
+import { resolveEffectiveTerminalProtocol } from '../../domain/terminalProtocol';
+import { findIncompleteProxyIdentityId, findMissingProxyIdentityId, hasUsableProxyConfig } from '../../domain/proxyProfiles';
+import { buildSftpHostCredentials } from './sftp/useSftpHostCredentials';
+import { buildTransferPoolKey } from './sftp/transferConnectionPool';
+import { createHostTerminalSession } from './sessionFactories';
+
+type HostOpenSessionReuseInput = {
+  sessions: TerminalSession[];
+  hosts: Host[];
+  keys: SSHKey[];
+  identities: Identity[];
+  resolveEffectiveHost: (host: Host) => Host;
+};
+
+type OpeningConnection = { localHost: Host } | { key: Promise<string | undefined> };
+
+/** Retain the opening connection identity, never credentials in session storage. */
+export function useHostOpenSessionReuse({ sessions, hosts, keys, identities, resolveEffectiveHost }: HostOpenSessionReuseInput) {
+  const openingKeys = useRef(new Map<string, OpeningConnection>());
+  const connectionKey = useCallback((host: Host) => {
+    const protocol = resolveEffectiveTerminalProtocol(host);
+    if (protocol === 'local') {
+      const options = {
+        hostname: host.hostname,
+        username: '',
+        localShell: host.localShell || undefined,
+        // The renderer starter omits both absent and empty args so the
+        // backend chooses its discovered/login defaults for either form.
+        localShellArgs: host.localShellArgs?.length ? host.localShellArgs : undefined,
+        localStartDir: host.localStartDir || '~',
+      };
+      return buildTransferPoolKey({ hostname: host.hostname, hostId: host.id, protocol, connectionOptions: options });
+    }
+    if (protocol === 'telnet') {
+      // The actual Telnet starter rejects these settings before connecting.
+      if ((host.proxyProfileId && !host.proxyConfig)
+        || findMissingProxyIdentityId(host.proxyConfig, identities)
+        || findIncompleteProxyIdentityId(host.proxyConfig, identities)
+        || hasUsableProxyConfig(host.proxyConfig)) {
+        throw new Error('Telnet proxy configuration cannot be used');
+      }
+      // Match the actual Telnet starter, including explicit empty overrides.
+      const identity = host.telnetIdentityId ? identities.find((item) => item.id === host.telnetIdentityId) : undefined;
+      if (host.telnetIdentityId && (!identity?.username?.trim() || identity.password === undefined)) {
+        throw new Error('Telnet identity is missing or incomplete');
+      }
+      const rawPassword = identity ? identity.password : resolveTelnetPassword(host);
+      if (isEncryptedCredentialPlaceholder(rawPassword)) throw new Error('Telnet credentials are unavailable');
+      const options = {
+        hostname: host.hostname,
+        port: resolveTelnetPort(host),
+        username: identity ? identity.username?.trim() : resolveTelnetUsername(host),
+        password: sanitizeCredentialValue(rawPassword),
+      };
+      return buildTransferPoolKey({ ...options, hostId: host.id, protocol, connectionOptions: options });
+    }
+    // Reuse the existing credential/chain expansion and transport identity
+    // comparison. Presentation names and SFTP-only choices do not change a
+    // terminal's destination or login.
+    if (protocol === 'serial' && isEncryptedCredentialPlaceholder(host.password)) throw new Error('Serial credentials are unavailable');
+    const options = buildSftpHostCredentials({
+      host, hosts: hosts.map(resolveEffectiveHost), keys, identities,
+    });
+    delete options.sudo;
+    delete options.fileProtocol;
+    for (const hop of options.jumpHosts ?? []) delete hop.label;
+    const connectionOptions = {
+      ...options,
+      protocol,
+      moshEnabled: host.moshEnabled,
+      moshServerPath: host.moshServerPath,
+      etEnabled: host.etEnabled,
+      etPort: host.etPort,
+      etJumpPorts: protocol === 'et'
+        ? host.hostChain?.hostIds.map((id) => hosts.find((item) => item.id === id)).map((hop) => hop && (resolveEffectiveHost(hop).etPort ?? 2022))
+        : undefined,
+      pluginConnection: host.pluginConnection,
+      serialConfig: protocol === 'serial' ? createHostTerminalSession('', host).serialConfig : undefined,
+      serialLogin: protocol === 'serial' ? { username: host.username?.trim(), password: sanitizeCredentialValue(host.password) } : undefined,
+      agentForwarding: host.agentForwarding,
+      x11Forwarding: host.x11Forwarding,
+    };
+    return buildTransferPoolKey({ ...options, protocol: connectionOptions.protocol, connectionOptions });
+  }, [hosts, keys, identities, resolveEffectiveHost]);
+
+  useLayoutEffect(() => {
+    const liveIds = new Set(sessions.map((session) => session.id));
+    for (const id of openingKeys.current.keys()) {
+      if (!liveIds.has(id)) openingKeys.current.delete(id);
+    }
+    for (const session of sessions) {
+      if (openingKeys.current.has(session.id) || session.restoreState) continue;
+      const host = hosts.find((candidate) => candidate.id === session.hostId);
+      if (!host) continue;
+      try {
+        const effectiveHost = resolveEffectiveHost(host);
+        const openingHost = {
+          ...effectiveHost,
+          hostname: session.hostname,
+          username: session.protocol === 'serial' ? resolveEffectiveHost(host).username : session.username,
+          port: session.port ?? host.port,
+          protocol: session.protocol ?? host.protocol,
+          moshEnabled: session.moshEnabled ?? host.moshEnabled,
+          etEnabled: session.etEnabled ?? host.etEnabled,
+          serialConfig: session.serialConfig ?? host.serialConfig,
+          pluginConnection: session.pluginConnection ?? host.pluginConnection,
+          localShell: session.localShell ?? effectiveHost.localShell,
+          localShellArgs: session.localShellArgs ?? effectiveHost.localShellArgs,
+          localStartDir: session.localStartDir ?? effectiveHost.localStartDir,
+        };
+        // Local IDs may only resolve after renderer discovery completes. Keep
+        // the opening settings so that later discovery can identify the same
+        // executable without replacing them with edited vault/global settings.
+        openingKeys.current.set(session.id, resolveEffectiveTerminalProtocol(openingHost) === 'local'
+          ? { localHost: openingHost }
+          : { key: connectionKey(openingHost).catch(() => undefined) });
+      } catch {
+        openingKeys.current.set(session.id, { key: Promise.resolve(undefined) });
+      }
+    }
+  }, [sessions, hosts, connectionKey, resolveEffectiveHost]);
+
+  return useCallback(async (hostId: string) => {
+    const host = hosts.find((candidate) => candidate.id === hostId);
+    if (!host) return undefined;
+    try {
+      const requestedKey = await connectionKey(resolveEffectiveHost(host));
+      const matches = await Promise.all(sessions.map(async (session) => {
+        if (session.hostId !== hostId) return undefined;
+        const opening = openingKeys.current.get(session.id);
+        const openingKey = opening && ('localHost' in opening
+          // An explicit empty selector means backend default, not today's
+          // global setting. Nonempty captured IDs can safely resolve now.
+          ? connectionKey(opening.localHost.localShell ? resolveEffectiveHost(opening.localHost) : opening.localHost)
+          : opening.key);
+        return await openingKey === requestedKey ? session : undefined;
+      }));
+      return findReusableHostSession(matches.filter((session) => session !== undefined), hostId);
+    } catch {
+      // An unresolved/changed credential must never select an old transport.
+      return undefined;
+    }
+  }, [hosts, sessions, connectionKey, resolveEffectiveHost]);
+}

application/state/useSessionState.ts

@@ -1098,17 +1098,12 @@ export const useSessionState = ({
     if (targetHosts.length === 0) return;
     const resolvedCommand = commandOverride ?? snippet.command;
 
-    // Create sessions for each target host
-    const newSessions: TerminalSession[] = targetHosts.map(host => ({
-      id: crypto.randomUUID(),
-      hostId: host.id,
-      hostLabel: host.label,
-      hostname: host.hostname,
-      username: host.username,
-      status: 'connecting' as const,
-      charset: host.charset,
-      // workspaceId will be set after workspace is created
-    }));
+    // Create sessions for each target host. createHostTerminalSession copies
+    // protocol, shellType, and local-shell metadata, so local vault hosts keep
+    // their transport info (session consumers treat a missing protocol as SSH).
+    const newSessions: TerminalSession[] = targetHosts.map(host =>
+      createHostTerminalSession(crypto.randomUUID(), host),
+    );
 
     const sessionIds = newSessions.map(s => s.id);
     

application/state/useVaultAgentBridge.ts

@@ -53,6 +53,7 @@ export interface UseVaultAgentBridgeInput {
   stopTunnel: VaultAgentApiDeps['stopTunnel'];
   stopRuleTunnels: VaultAgentApiDeps['stopRuleTunnels'];
   openHost?: VaultAgentApiDeps['openHost'];
+  findExistingSessionForHost?: VaultAgentApiDeps['findExistingSessionForHost'];
   closeSession?: VaultAgentApiDeps['closeSession'];
   getScriptSessionMeta?: (sessionId: string) => Pick<TerminalSession, 'status' | 'customName' | 'hostLabel' | 'hostname' | 'username'> | undefined;
 }
@@ -271,6 +272,7 @@ export function useVaultAgentBridge(input: UseVaultAgentBridgeInput): void {
         openHost: current.openHost
           ? (host, isExternalMcpCall) => current.openHost!(host, isExternalMcpCall)
           : undefined,
+        findExistingSessionForHost: current.findExistingSessionForHost,
         closeSession: current.closeSession
           ? (sessionId) => current.closeSession!(sessionId)
           : undefined,

components/AIChatPanelContent.tsx

@@ -1,5 +1,5 @@
 import React, { type Dispatch, type SetStateAction } from 'react';
-import { History, Plus } from 'lucide-react';
+import { History, Plus, Undo2 } from 'lucide-react';
 import type { AIPermissionMode, AISession, ChatMessage, DiscoveredAgent, ExternalAgentConfig, AgentModelPreset, ProviderConfig, UploadedFile } from '../infrastructure/ai/types';
 import type { Host, VaultNote } from '../types';
 import type { UserSkillOption } from './ai/userSkillsState';
@@ -47,6 +47,8 @@ interface AIChatPanelContentProps {
   activeSessionId: string | null;
   handleSelectSession: (sessionId: string) => void;
   handleDeleteSession: (event: React.MouseEvent, sessionId: string) => void;
+  /** Fork the conversation up to a completed assistant response into a new session. */
+  onForkFromMessage?: (messageId: string) => void;
   messages: ChatMessage[];
   isStreaming: boolean;
   activeCompaction?: import('../application/state/useAgentCompactionUi').ActiveCompactionUi | null;
@@ -55,6 +57,9 @@ interface AIChatPanelContentProps {
   setInputValue: (value: string) => void;
   handleSend: () => void;
   handleCompact: () => void;
+  /** Undo last turn is offered at a safe boundary (never mid-tool / mid-compaction). */
+  canUndoLastTurn?: boolean;
+  handleUndoLastTurn?: () => void;
   canCompact?: boolean;
   handleSteer: () => void;
   handleStop: () => void;
@@ -124,6 +129,7 @@ export const AIChatPanelContent: React.FC<AIChatPanelContentProps> = ({
   activeSessionId,
   handleSelectSession,
   handleDeleteSession,
+  onForkFromMessage,
   messages,
   isStreaming,
   activeCompaction = null,
@@ -132,6 +138,8 @@ export const AIChatPanelContent: React.FC<AIChatPanelContentProps> = ({
   setInputValue,
   handleSend,
   handleCompact,
+  canUndoLastTurn = false,
+  handleUndoLastTurn,
   canCompact = false,
   handleSteer,
   handleStop,
@@ -232,6 +240,23 @@ export const AIChatPanelContent: React.FC<AIChatPanelContentProps> = ({
               onManageAgents={handleOpenSettings}
             />
             <div className="flex items-center gap-0.5">
+              {handleUndoLastTurn && (
+                <Tooltip>
+                  <TooltipTrigger asChild>
+                    <Button
+                      variant="ghost"
+                      size="icon"
+                      className="h-6 w-6 rounded-md text-muted-foreground/62 hover:bg-white/[0.05] hover:text-foreground"
+                      aria-label={t('ai.chat.undoLastTurn')}
+                      disabled={sending || isStreaming || !canUndoLastTurn}
+                      onClick={handleUndoLastTurn}
+                    >
+                      <Undo2 size={12} />
+                    </Button>
+                  </TooltipTrigger>
+                  <TooltipContent>{t('ai.chat.undoLastTurn')}</TooltipContent>
+                </Tooltip>
+              )}
               <ConversationExport
                 session={activeSession}
                 onExport={handleExport}
@@ -291,6 +316,8 @@ export const AIChatPanelContent: React.FC<AIChatPanelContentProps> = ({
                 isStreaming={isStreaming}
                 activeSessionId={activeSessionId}
                 activeCompaction={activeCompaction}
+                contextCompaction={activeSession?.contextCompaction}
+                onForkFromMessage={onForkFromMessage}
                 notes={notes}
                 hosts={hosts}
                 onOpenVaultNote={onOpenVaultNote}

components/AIChatSidePanel.mountRetention.test.ts

@@ -120,7 +120,9 @@ test('send preflight aborts after the panel unmounts or the scope changes', () =
 test('send preflight locks header agent and new-chat controls', () => {
   const panel = readFileSync(new URL('./AIChatSidePanel.tsx', import.meta.url), 'utf8');
   const content = readFileSync(new URL('./AIChatPanelContent.tsx', import.meta.url), 'utf8');
-  assert.match(panel, /sending=\{isSending\}/);
+  // `sending` also covers an in-flight undo-last-turn so the header controls
+  // (and a quick send) stay locked while the branch materializes.
+  assert.match(panel, /sending=\{isSending \|\| isUndoingLastTurn\}/);
   assert.match(content, /disabled=\{sending\}/);
   const selector = readFileSync(new URL('./ai/AgentSelector.tsx', import.meta.url), 'utf8');
   assert.match(selector, /if \(parked \|\| disabled\) setOpen\(false\)/);

components/AIChatSidePanel.tsx

@@ -65,6 +65,7 @@ import {
 } from '../application/state/useAIChatStreaming';
 import { getScopedHistorySessions } from './ai/scopedHistorySessions';
 import { resolveInheritedAIActiveSessionId } from '../domain/aiWorkspaceScopeInherit';
+import { resolveUndoLastTurnBoundary } from '../domain/aiUndoLastTurn';
 import { aiSessionIdSetEqual, exactScopeAISessionsEqual } from '../domain/aiSessionsForScope';
 import { buildExternalAgentHistoryMessagesForBridge } from './ai/externalAgentHistory';
 import { canSendWithAgent, findEnabledExternalAgent } from './ai/agentSendEligibility';
@@ -269,6 +270,7 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
   addDraftFiles,
   removeDraftFile,
   createSession,
+  undoLastTurnInSession,
   deleteSession,
   updateSessionTitle,
   updateSessionExternalSessionId,
@@ -276,6 +278,7 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
   updateLastMessage,
   updateMessageById,
   persistContextCompaction,
+  forkSessionFromMessage,
   providers,
   activeProviderId,
   activeModelId,
@@ -319,6 +322,11 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
 
   const [showHistory, setShowHistory] = useState(false);
   const [isSending, setIsSending] = useState(false);
+  // Undo-last-turn is still
+  // running. Unlike the send flow this is not reflected in `isSending`, so it
+  // is tracked separately to block sends until the branch settles: a turn
+  // submitted meanwhile would run against the (soon hidden) source session.
+  const [isUndoingLastTurn, setIsUndoingLastTurn] = useState(false);
   const [runtimeAgentModelPresets, setRuntimeAgentModelPresets] = useState<Record<string, { cacheKey: string; models: AgentModelPreset[] }>>({});
   const [runtimeModelWarnings, setRuntimeModelWarnings] = useState<Record<string, { cacheKey: string; message: string }>>({});
   // Tracks SDK runtime model catalogs currently loading (per agent scope):
@@ -821,6 +829,78 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
     && Boolean(effectiveActiveProvider)
     && Boolean(effectiveActiveModelId.trim());
 
+  // Undo last turn: offered only at a safe boundary (never inside a compacted
+  // prefix, never between an assistant tool call and its result).
+  const canUndoLastTurn = useMemo(() => Boolean(
+    activeSession
+    && !isStreaming
+    && resolveUndoLastTurnBoundary(
+      activeSession.messages,
+      activeSession.contextCompaction?.compactedMessageCount ?? 0,
+    ) != null,
+  ), [activeSession, isStreaming]);
+
+  const undoInFlightRef = useRef(false);
+  const handleUndoLastTurn = useCallback(async () => {
+    const sessionId = activeSessionRef.current?.id;
+    if (!sessionId || !undoLastTurnInSession) return;
+    if (isStreaming || isAIChatSessionStreaming(sessionId)) return;
+    // Serialize: while a branch is still being created, `canUndoLastTurn` stays stale, so a quick second
+    // click must not start a parallel undo of the same session — that would
+    // publish duplicate branches and restore the same prompt twice.
+    if (undoInFlightRef.current) return;
+    undoInFlightRef.current = true;
+    setIsUndoingLastTurn(true);
+    try {
+      const result = await undoLastTurnInSession(sessionId);
+      if (!result) return;
+
+      ensureScopeDraft(currentAgentId);
+      // Text typed since the last flush lives only in the live composer buffer
+      // (pendingComposerTextRef/currentDraftRef), not in the persisted draft;
+      // merge from the live buffer so it is not lost, then drop the pending
+      // buffer so the later flushDraftText() cannot overwrite the merged text.
+      const liveDraft = currentDraftRef.current;
+      updateScopeDraft(currentAgentId, (draft) => {
+        const liveText = liveDraft?.text ?? draft.text;
+        const liveSkillSlugs = liveDraft?.selectedUserSkillSlugs ?? draft.selectedUserSkillSlugs;
+        return {
+          ...draft,
+          // Keep anything the user is still typing; the undone prompt goes first.
+          text: liveText.trim()
+            ? `${result.restored.text}\n\n${liveText}`
+            : result.restored.text,
+          attachments: [
+            ...result.restored.attachments,
+            ...(liveDraft?.attachments ?? draft.attachments),
+          ],
+          // The undone turn was selected with these pills; keep any pills the
+          // user picked since the send on top of them.
+          selectedUserSkillSlugs: [
+            ...result.restored.selectedUserSkillSlugs,
+            ...liveSkillSlugs.filter((slug) => !result.restored.selectedUserSkillSlugs.includes(slug)),
+          ],
+        };
+      });
+      discardPendingComposerText();
+      showScopeSessionView(result.sessionId);
+      // Tool side effects live outside the conversation and cannot be rolled back.
+      toast.info(t('ai.chat.undoLastTurnNotice'));
+    } finally {
+      undoInFlightRef.current = false;
+      setIsUndoingLastTurn(false);
+    }
+  }, [
+    discardPendingComposerText,
+    ensureScopeDraft,
+    isStreaming,
+    showScopeSessionView,
+    t,
+    undoLastTurnInSession,
+    updateScopeDraft,
+    currentAgentId,
+  ]);
+
   const providersRef = useRef(providers);
   providersRef.current = providers;
 
@@ -1177,8 +1257,8 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
 
   const inputAgentId = activeSession?.agentId ?? currentDraft?.agentId ?? currentAgentId;
   const canSendCurrentAgent = useMemo(
-    () => !isSending && canSendWithAgent(inputAgentId, externalAgents),
-    [inputAgentId, externalAgents, isSending],
+    () => !isSending && !isUndoingLastTurn && canSendWithAgent(inputAgentId, externalAgents),
+    [inputAgentId, externalAgents, isSending, isUndoingLastTurn],
   );
 
   const handleAgentModelSelect = useCallback((modelId: string) => {
@@ -1314,6 +1394,10 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
     }));
     const hasInlineTextAttachments = attachments.some(isInlineTextAttachment);
     if ((!trimmed && !hasInlineTextAttachments) || isStreaming) return;
+    // While undo-last-turn is creating the branch, the target is still the source; a
+    // turn submitted now would run in the soon-hidden source session, so
+    // block it until the branch settles.
+    if (isUndoingLastTurn) return;
     // Note-only sends (empty text + a mentioned note) still need a usable
     // session title: fall back to the first mentioned note's title so these
     // conversations don't all show up as "Untitled" in history.
@@ -1438,6 +1522,7 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
         addMessageToSession(sessionId, {
           id: generateId(), role: 'user', content: trimmed,
           ...(attachments.length > 0 ? { attachments } : {}),
+          ...(selectedSkillSlugs.length > 0 ? { selectedUserSkillSlugs: selectedSkillSlugs } : {}),
           timestamp: Date.now(),
         });
         addMessageToSession(sessionId, { id: generateId(), role: 'assistant', content: t('ai.chat.noProvider'), timestamp: Date.now() });
@@ -1452,6 +1537,7 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
         addMessageToSession(sessionId, {
           id: generateId(), role: 'user', content: trimmed,
           ...(attachments.length > 0 ? { attachments } : {}),
+          ...(selectedSkillSlugs.length > 0 ? { selectedUserSkillSlugs: selectedSkillSlugs } : {}),
           timestamp: Date.now(),
         });
         addMessageToSession(sessionId, { id: generateId(), role: 'assistant', content: t('ai.chat.noProviderModel'), timestamp: Date.now() });
@@ -1465,6 +1551,8 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
       addMessageToSession(sessionId, {
         id: generateId(), role: 'user', content: trimmed,
         ...(attachments.length > 0 ? { attachments } : {}),
+        // Kept on the user message so undo last turn can restore the pills.
+        ...(selectedSkillSlugs.length > 0 ? { selectedUserSkillSlugs: selectedSkillSlugs } : {}),
         timestamp: Date.now(),
       });
       clearScopeDraft({ keepPendingText: keepPendingAfterSend() });
@@ -1546,7 +1634,7 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
     }
   }, [
     validateNoteMentions, loadCodexConfigModel,
-    isStreaming, activeProvider, effectiveActiveProvider, effectiveActiveModelId, selectedCattyThinking, scopeKey, currentAgentId,
+    isStreaming, isUndoingLastTurn, activeProvider, effectiveActiveProvider, effectiveActiveModelId, selectedCattyThinking, scopeKey, currentAgentId,
     activeModelId, externalAgents,
     createSession, addMessageToSession, updateMessageById, updateLastMessage,
     setStreamingForScope,
@@ -1767,6 +1855,36 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
     [setActiveSessionId, showScopeSessionView],
   );
 
+  // "Fork from here": copy the viewed conversation up to a completed assistant
+  // response into a new session, switch to it, and confirm via toast. The
+  // original stays in history. Boundary validation is re-run by the state
+  // hook; a null result means the fork was refused (already hidden in the UI).
+  // This panel's scope is passed so the branch is created in the scope viewing
+  // it, even when the source session's own scope went stale (e.g. a terminal
+  // chat resumed after reconnecting under a new terminal id).
+  const handleForkFromMessage = useCallback(async (messageId: string) => {
+    const sourceSessionId = activeSessionRef.current?.id ?? activeSessionId;
+    if (!sourceSessionId) return;
+    // Reject a double-click while the new session is being selected so one
+    // interaction cannot create two forks.
+    if (!tryBeginSendForKey(`fork:${sourceSessionId}`)) return;
+    try {
+      const fork = await forkSessionFromMessage?.(sourceSessionId, messageId, {
+        type: scopeType,
+        targetId: scopeTargetId,
+      });
+      if (!fork) return;
+      applyHistorySessionSelection(fork.id, {
+        showSessionView: showScopeSessionView,
+        setActiveSessionId,
+        closeHistory: () => setShowHistory(false),
+      });
+      toast.success(t('ai.chat.forkCreated'));
+    } finally {
+      endSendForKey(`fork:${sourceSessionId}`);
+    }
+  }, [activeSessionId, forkSessionFromMessage, scopeTargetId, scopeType, setActiveSessionId, showScopeSessionView, t]);
+
   const handleDeleteSession = useCallback(
     async (e: React.MouseEvent, sessionId: string) => {
       e.stopPropagation();
@@ -1834,7 +1952,7 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
       >
       <AIChatPanelContent
         parked={!isVisible}
-        sending={isSending}
+        sending={isSending || isUndoingLastTurn}
         t={t}
         currentAgentId={currentAgentId}
         externalAgents={externalAgents}
@@ -1853,6 +1971,7 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
         activeSessionId={activeSessionId}
         handleSelectSession={handleSelectSession}
         handleDeleteSession={handleDeleteSession}
+        onForkFromMessage={handleForkFromMessage}
         messages={messages}
         isStreaming={isStreaming}
         activeCompaction={
@@ -1864,6 +1983,8 @@ const AIChatSidePanelActive: React.FC<AIChatSidePanelProps> = ({
         setInputValue={setInputValue}
         handleSend={handleSend}
         handleCompact={handleCompact}
+        canUndoLastTurn={canUndoLastTurn}
+        handleUndoLastTurn={undoLastTurnInSession ? handleUndoLastTurn : undefined}
         handleSteer={handleSteer}
         handleStop={handleStop}
         canSteer={canSteerCurrentTurn}
@@ -1941,6 +2062,7 @@ const AI_CHAT_SIDE_PANEL_AI_STATE_KEYS = [
   'updateLastMessage',
   'updateMessageById',
   'persistContextCompaction',
+  'forkSessionFromMessage',
   'providers',
   'activeProviderId',
   'activeModelId',

components/AIChatSidePanel.types.ts

@@ -37,6 +37,10 @@ export interface AIChatSidePanelProps {
   addDraftFiles: (scopeKey: string, fallbackAgentId: string, inputFiles: File[]) => Promise<void>;
   removeDraftFile: (scopeKey: string, fallbackAgentId: string, fileId: string) => void;
   createSession: (scope: AISessionScope, agentId?: string) => AISession;
+  /** Non-destructively branch before the last user turn; returns the branch id + restored composer content. */
+  undoLastTurnInSession?: (
+    sessionId: string,
+  ) => Promise<{ sessionId: string; restored: { text: string; attachments: import('../infrastructure/ai/types').UploadedFile[]; selectedUserSkillSlugs: string[] } } | null>;
   deleteSession: (sessionId: string, scopeKey?: string) => void;
   updateSessionTitle: (sessionId: string, title: string) => void;
   updateSessionExternalSessionId: (sessionId: string, externalSessionId: string | undefined) => void;
@@ -54,6 +58,11 @@ export interface AIChatSidePanelProps {
     sessionId: string,
     compaction: import('../infrastructure/ai/types').AISessionContextCompaction,
   ) => void;
+  forkSessionFromMessage?: (
+    sessionId: string,
+    messageId: string,
+    viewingScope?: Pick<AISessionScope, 'type' | 'targetId'>,
+  ) => Promise<AISession | null>;
   // Provider config
   providers: ProviderConfig[];
   activeProviderId: string;

components/GroupDetailsPanel.tsx

@@ -25,6 +25,7 @@ import {
   formatProxyConfigType,
   updateProxyConfigField,
 } from "../domain/proxyProfiles";
+import { canServeAsSshJumpHost } from "../domain/terminalProtocol";
 import {
   EnvVar,
   GroupConfig,
@@ -333,7 +334,12 @@ const GroupDetailsPanel: React.FC<GroupDetailsPanelPropsWithResize> = ({
 
   const availableHostsForChain = useMemo(() => {
     const chainedIds = new Set(form.hostChain?.hostIds || []);
-    return allHosts.filter((h) => !chainedIds.has(h.id));
+    // Chain hops are SSH ProxyJump hops; never offer local/serial/telnet/plugin
+    // entries (e.g. saved local shells) as jump hosts.
+    return allHosts.filter((h) =>
+      !chainedIds.has(h.id)
+      && canServeAsSshJumpHost(h),
+    );
   }, [allHosts, form.hostChain?.hostIds]);
 
   const addHostToChain = (hostId: string) => {

components/HostDetailsPanel.tsx

@@ -23,6 +23,7 @@ import {
   updateProxyConfigField,
 } from "../domain/proxyProfiles";
 import { hasRequiredHostAuthCredential, resolveHostAuth, resolveHostAuthMethodForPersistence } from "../domain/sshAuth";
+import { canServeAsSshJumpHost } from "../domain/terminalProtocol";
 import { customThemeStore } from "../application/state/customThemeStore";
 import {
   hasHostFontSizeOverride,
@@ -749,7 +750,13 @@ const HostDetailsPanel: React.FC<HostDetailsPanelPropsWithResize> = ({
 
   const availableHostsForChain = useMemo(() => {
     const chainedIds = new Set(form.hostChain?.hostIds || []);
-    return allHosts.filter((h) => h.id !== form.id && !chainedIds.has(h.id));
+    // Chain hops are SSH ProxyJump hops; never offer local/serial/telnet/plugin
+    // entries (e.g. saved local shells) as jump hosts.
+    return allHosts.filter((h) =>
+      h.id !== form.id
+      && !chainedIds.has(h.id)
+      && canServeAsSshJumpHost(h),
+    );
   }, [allHosts, form.id, form.hostChain?.hostIds]);
 
   const chainedHosts = useMemo(() => {

components/HostTreeView.tsx

@@ -16,6 +16,7 @@ import {
   type HostClickBehavior,
 } from '../domain/hostClickBehavior';
 import { sortByVaultOrder } from '../domain/vaultOrder';
+import { getVaultHostRowSubtitle } from '../domain/localShellHost';
 import { STORAGE_KEY_VAULT_HOSTS_TREE_EXPANDED } from '../infrastructure/config/storageKeys';
 import { GroupConfig, GroupNode, Host } from '../types';
 import { Collapsible, CollapsibleContent, CollapsibleTrigger } from './ui/collapsible';
@@ -726,6 +727,7 @@ const HostTreeItem: React.FC<HostTreeItemProps> = ({
   initialTreeItemKey,
   onActiveTreeItemChange,
 }) => {
+  const { t } = useI18n();
   const safeHost = sanitizeHost(host);
   const tags = host.tags || [];
   const displayDetails = useMemo(
@@ -843,7 +845,9 @@ const HostTreeItem: React.FC<HostTreeItemProps> = ({
                 <HostNotesIndicator notes={host.notes} />
               </div>
               <div className="truncate text-[11px] leading-4 text-muted-foreground">
-                {displayUsername}@{host.hostname}:{displayPort}
+                {displayProtocol === 'local'
+                  ? getVaultHostRowSubtitle(safeHost, { localFallback: t('localShell.subtitle') })
+                  : `${displayUsername}@${host.hostname}:${displayPort}`}
               </div>
             </div>
           )}

components/LocalShellHostDetailsPanel.test.tsx

@@ -0,0 +1,101 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import React from "react";
+import { renderToStaticMarkup } from "react-dom/server";
+import { readFileSync } from "node:fs";
+
+import { LocalShellHostDetailsPanel } from "./LocalShellHostDetailsPanel.tsx";
+import type { Host } from "../types.ts";
+
+const panelSource = readFileSync(
+  new URL("./LocalShellHostDetailsPanel.tsx", import.meta.url),
+  "utf8",
+);
+
+const existingLocalHost = {
+  id: "local-existing",
+  label: "Project A CMD",
+  hostname: "localhost",
+  username: "",
+  tags: ["local"],
+  group: "Projects/A",
+  protocol: "local",
+  os: "linux",
+  createdAt: 0,
+  localShell: "powershell",
+  localShellName: "Windows PowerShell",
+  localShellIcon: "powershell",
+} as unknown as Host;
+
+const noop = () => {};
+
+test("renderToStaticMarkup: create mode shows title, default-shell option and Save & Connect", () => {
+  const markup = renderToStaticMarkup(
+    <LocalShellHostDetailsPanel
+      defaultGroup="Projects/A"
+      groups={["Projects/A", "Infra"]}
+      onSave={noop}
+      onSaveAndConnect={noop}
+      onCancel={noop}
+      layout="inline"
+    />,
+  );
+
+  assert.match(markup, /localShell\.panel\.title/);
+  assert.match(markup, /localShell\.field\.shellDefault/);
+  assert.match(markup, /localShell\.saveAndConnect/);
+  assert.match(markup, /localShell\.saveAndConnect|common\.save/);
+});
+
+test("renderToStaticMarkup: edit mode hides Save & Connect and shows existing shell", () => {
+  const markup = renderToStaticMarkup(
+    <LocalShellHostDetailsPanel
+      initialData={existingLocalHost}
+      groups={["Projects/A"]}
+      onSave={noop}
+      onCancel={noop}
+      layout="inline"
+    />,
+  );
+
+  assert.match(markup, /localShell\.panel\.title\.edit/);
+  assert.doesNotMatch(markup, /localShell\.saveAndConnect/);
+  // Existing label is carried into the form
+  assert.match(markup, /Project A CMD/);
+  assert.match(markup, /local-shell-start-dir/);
+});
+
+test("buildHost preserves the saved OS on edits and detects it only for new entries", () => {
+  // Editing must retain initialData.os: entries imported/synced on one
+  // platform must not be re-classified as the editor machine's OS on save.
+  assert.match(
+    panelSource,
+    /os:\s*initialData\?\.os \?\? detectLocalOs\(navigator\.userAgent \|\| navigator\.platform\)/,
+  );
+});
+
+test("unchanged shell selection keeps stored metadata over discovery", () => {
+  // A host with custom localShellArgs for a shell id that discovery also
+  // matches must keep its stored args/name/icon when an unrelated edit
+  // (label, tag, group) is saved; discovered metadata applies only after
+  // the user changes the shell selection.
+  const unchanged = panelSource.match(
+    /const shellMeta =\s*\n[\s\S]*?shell === initialData\?\.localShell\s*\n\s*\?\s*\{[\s\S]*?\}\s*\n\s*: matchedShell;/,
+  );
+  assert.ok(unchanged, "shellMeta must branch on an unchanged shell selection");
+  // Inside the unchanged branch, stored metadata wins per field and
+  // matchedShell is only a fallback (never the primary source).
+  assert.match(
+    unchanged[0],
+    /args:\s*initialData\?\.localShellArgs \?\? matchedShell\?\.args/,
+  );
+  assert.match(
+    unchanged[0],
+    /name:\s*initialData\?\.localShellName \?\? matchedShell\?\.name/,
+  );
+  assert.match(
+    unchanged[0],
+    /icon:\s*initialData\?\.localShellIcon \?\? matchedShell\?\.icon/,
+  );
+  assert.doesNotMatch(unchanged[0], /matchedShell \?\?/);
+});

components/LocalShellHostDetailsPanel.tsx

@@ -0,0 +1,255 @@
+/**
+ * Local Shell Host Details Panel
+ * A dedicated editor for local shell / CMD vault hosts (protocol 'local'),
+ * distinct from the SSH HostDetailsPanel. Lets users save named local shells
+ * into vault groups next to their SSH hosts (issue #3615).
+ */
+import { Save, TerminalSquare, X } from 'lucide-react';
+import React, { useMemo, useState } from 'react';
+import { useI18n } from '../application/i18n/I18nProvider';
+import { useDiscoveredShells } from '../lib/useDiscoveredShells';
+import { detectLocalOs } from '../lib/localShell';
+import type { Host } from '../domain/models';
+import { createLocalShellHost } from '../domain/localShellHost';
+
+import { Button } from './ui/button';
+import { Combobox, ComboboxOption } from './ui/combobox';
+import { Input } from './ui/input';
+import { Label } from './ui/label';
+import {
+  AsidePanel,
+  AsidePanelContent,
+  AsidePanelFooter,
+  type AsidePanelLayout,
+  type AsidePanelResizeProps,
+} from './ui/aside-panel';
+import { cn } from '../lib/utils';
+
+interface LocalShellHostDetailsPanelProps {
+  /** Existing host when editing; null/undefined when creating a new entry. */
+  initialData?: Host | null;
+  defaultGroup?: string;
+  groups?: string[];
+  onSave: (host: Host) => void;
+  /** Saves the host and immediately opens a terminal for it. */
+  onSaveAndConnect?: (host: Host) => void;
+  onCancel: () => void;
+  layout?: AsidePanelLayout;
+  className?: string;
+}
+
+type LocalShellHostDetailsPanelPropsWithResize =
+  LocalShellHostDetailsPanelProps & AsidePanelResizeProps;
+
+export const LocalShellHostDetailsPanel: React.FC<LocalShellHostDetailsPanelPropsWithResize> = ({
+  initialData,
+  defaultGroup,
+  groups = [],
+  onSave,
+  onSaveAndConnect,
+  onCancel,
+  layout = 'overlay',
+  className,
+  resizable,
+  persistWidthStorageKey,
+  resizeAriaLabel,
+}) => {
+  const { t } = useI18n();
+  const discoveredShells = useDiscoveredShells();
+
+  const [label, setLabel] = useState(initialData?.label ?? '');
+  const [shell, setShell] = useState(initialData?.localShell ?? '');
+  const [startDir, setStartDir] = useState(initialData?.localStartDir ?? '');
+  // On creation, initialize from defaultGroup so the field reflects what a
+  // plain save would persist; clearing it then intentionally saves at the
+  // vault root. Edits keep the host's own group (possibly empty).
+  const [group, setGroup] = useState(
+    initialData ? initialData.group ?? '' : defaultGroup ?? '',
+  );
+
+  const matchedShell = useMemo(
+    () => discoveredShells.find((candidate) => candidate.id === shell),
+    [discoveredShells, shell],
+  );
+
+  // While the shell selection is unchanged from the saved host, prefer the
+  // host's stored metadata: an imported/synced host may carry custom startup
+  // arguments for a shell id that also exists in discovery, and saving an
+  // unrelated edit (label, tag, group) must not overwrite them with the
+  // current discovery result. Discovered metadata applies only after the user
+  // changes the selection — or per-field when the host stores none.
+  const shellMeta =
+    shell && shell === initialData?.localShell
+      ? {
+          args: initialData?.localShellArgs ?? matchedShell?.args,
+          name: initialData?.localShellName ?? matchedShell?.name,
+          icon: initialData?.localShellIcon ?? matchedShell?.icon,
+        }
+      : matchedShell;
+
+  const shellOptions: ComboboxOption[] = useMemo(() => {
+    const options: ComboboxOption[] = [
+      { value: '', label: t('localShell.field.shellDefault') },
+    ];
+    for (const candidate of discoveredShells) {
+      options.push({
+        value: candidate.id,
+        label: candidate.name,
+        sublabel: candidate.command,
+      });
+    }
+    return options;
+  }, [discoveredShells, t]);
+
+  const groupOptions: ComboboxOption[] = useMemo(() => {
+    const allGroups = new Set(groups);
+    if (group && !allGroups.has(group)) {
+      allGroups.add(group);
+    }
+    return Array.from(allGroups).map((g) => ({
+      value: g,
+      label: g,
+    }));
+  }, [groups, group]);
+
+  const buildHost = (): Host => {
+    const host = createLocalShellHost({
+      id: initialData?.id,
+      // Keep the entry's saved OS on edits: importing/syncing on one platform
+      // then editing elsewhere must not silently re-classify the host (shell
+      // defaults, CSV round trips, dedup) as the editor machine's OS.
+      os: initialData?.os ?? detectLocalOs(navigator.userAgent || navigator.platform),
+      label,
+      shell,
+      shellArgs: shellMeta?.args,
+      shellName: shellMeta?.name,
+      shellIcon: shellMeta?.icon,
+      startDir,
+      // Save the controlled value directly: '' means the user explicitly
+      // cleared the group, which persists at the vault root.
+      group: group,
+      tags: initialData?.tags,
+      notes: initialData?.notes,
+    });
+    // On edits, merge over the existing host so fields this form does not
+    // expose (pinned, lastConnectedAt, order, ...) and the original
+    // creation timestamp survive a save.
+    return initialData
+      ? { ...initialData, ...host, createdAt: initialData.createdAt ?? host.createdAt }
+      : host;
+  };
+
+  const handleSave = () => onSave(buildHost());
+  const handleSaveAndConnect = () => {
+    if (!onSaveAndConnect) return;
+    onSaveAndConnect(buildHost());
+  };
+
+  return (
+    <AsidePanel
+      open={true}
+      onClose={onCancel}
+      title={initialData ? t('localShell.panel.title.edit') : t('localShell.panel.title')}
+      subtitle={initialData?.label}
+      className={cn('z-40', className)}
+      layout={layout}
+      dataSection="local-shell-host-details-panel"
+      resizable={resizable}
+      persistWidthStorageKey={persistWidthStorageKey}
+      resizeAriaLabel={resizeAriaLabel}
+    >
+      <AsidePanelContent>
+        {/* Label */}
+        <div className="space-y-2">
+          <Label htmlFor="local-shell-label">{t('localShell.field.label')}</Label>
+          <Input
+            id="local-shell-label"
+            value={label}
+            onChange={(e) => setLabel(e.target.value)}
+            placeholder={t('localShell.field.labelPlaceholder')}
+          />
+        </div>
+
+        {/* Shell */}
+        <div className="space-y-2">
+          <Label>{t('localShell.field.shell')}</Label>
+          <Combobox
+            options={shellOptions}
+            value={shell}
+            onValueChange={setShell}
+            placeholder={t('localShell.field.shellDefault')}
+            emptyText={t('localShell.field.shellEmpty')}
+            allowCreate
+            createText={t('common.use')}
+            icon={<TerminalSquare size={14} className="text-muted-foreground" />}
+          />
+          <p className="text-xs text-muted-foreground">
+            {matchedShell
+              ? t('localShell.field.shellResolved', { command: matchedShell.command })
+              : t('localShell.field.shellDefaultDesc')}
+          </p>
+        </div>
+
+        {/* Group */}
+        <div className="space-y-2">
+          <Label>{t('hostDetails.group')}</Label>
+          <Combobox
+            options={groupOptions}
+            value={group}
+            onValueChange={setGroup}
+            placeholder={t('hostDetails.selectGroup')}
+            allowCreate
+            createText={t('hostDetails.createGroup')}
+          />
+        </div>
+
+        {/* Start directory */}
+        <div className="space-y-2">
+          <Label htmlFor="local-shell-start-dir">{t('localShell.field.startDir')}</Label>
+          <div className="relative">
+            <Input
+              id="local-shell-start-dir"
+              value={startDir}
+              onChange={(e) => setStartDir(e.target.value)}
+              placeholder={t('localShell.field.startDirPlaceholder')}
+              className="pr-8"
+            />
+            {startDir && (
+              <button
+                type="button"
+                onClick={() => setStartDir('')}
+                aria-label={t('common.reset')}
+                className="absolute right-2 top-1/2 -translate-y-1/2 p-1 text-muted-foreground hover:text-foreground transition-colors"
+              >
+                <X size={14} />
+              </button>
+            )}
+          </div>
+        </div>
+      </AsidePanelContent>
+
+      <AsidePanelFooter>
+        <div className="flex gap-2">
+          <Button variant="ghost" onClick={onCancel} className="flex-1">
+            {t('common.cancel')}
+          </Button>
+          {onSaveAndConnect && !initialData && (
+            <Button
+              onClick={handleSaveAndConnect}
+              className="flex-1"
+            >
+              <TerminalSquare size={14} className="mr-2" />
+              {t('localShell.saveAndConnect')}
+            </Button>
+          )}
+          <Button onClick={handleSave} className="flex-1">
+            <Save size={14} className="mr-2" />
+            {t('common.save')}
+          </Button>
+        </div>
+      </AsidePanelFooter>
+    </AsidePanel>
+  );
+};
+
+export default LocalShellHostDetailsPanel;

components/SelectHostPanel.tsx

@@ -30,6 +30,8 @@ interface SelectHostPanelProps {
   resizable?: boolean;
   persistWidthStorageKey?: string;
   resizeAriaLabel?: string;
+  /** Allow saved local-shell (CMD/PowerShell/...) hosts as targets, e.g. snippet/script runners. */
+  allowLocalHosts?: boolean;
 }
 
 const SelectHostPanel: React.FC<SelectHostPanelProps> = ({
@@ -56,6 +58,7 @@ const SelectHostPanel: React.FC<SelectHostPanelProps> = ({
   resizable = false,
   persistWidthStorageKey,
   resizeAriaLabel,
+  allowLocalHosts = false,
 }) => {
   const { t } = useI18n();
   const [newHostPanelOpen, setNewHostPanelOpen] = useState(false);
@@ -103,6 +106,7 @@ const SelectHostPanel: React.FC<SelectHostPanelProps> = ({
         onSaveHost={onSaveHost}
         onCreateGroup={onCreateGroup}
         onNewHostPanelOpenChange={setNewHostPanelOpen}
+        allowLocalHosts={allowLocalHosts}
         className="flex-1 min-h-0"
       />
     </AsidePanel>

components/SelectHostPanelContent.tsx

@@ -58,6 +58,8 @@ export interface SelectHostPanelContentProps {
   onSaveHost?: (host: Host) => void;
   onCreateGroup?: (groupPath: string) => void;
   onNewHostPanelOpenChange?: (open: boolean) => void;
+  /** Allow saved local-shell (CMD/PowerShell/...) hosts as targets, e.g. snippet/script runners. */
+  allowLocalHosts?: boolean;
   className?: string;
 }
 
@@ -85,6 +87,7 @@ export const SelectHostPanelContent: React.FC<SelectHostPanelContentProps> = ({
   onSaveHost,
   onCreateGroup,
   onNewHostPanelOpenChange,
+  allowLocalHosts = false,
   className,
 }) => {
   const { t } = useI18n();
@@ -106,9 +109,14 @@ export const SelectHostPanelContent: React.FC<SelectHostPanelContentProps> = ({
     onNewHostPanelOpenChange?.(showNewHostPanel);
   }, [onNewHostPanelOpenChange, showNewHostPanel]);
 
+  // This panel picks hosts for SSH-backed capabilities (tunnels, keychain
+  // key export targets); serial hosts have no SSH session to target and, by
+  // default, neither do local-shell hosts. Snippet/script target pickers pass
+  // `allowLocalHosts` because their domain treats every non-serial host
+  // (including saved CMD/PowerShell shells) as a runnable target.
   const selectableHosts = useMemo(
-    () => hosts.filter((host) => host.protocol !== 'serial'),
-    [hosts],
+    () => hosts.filter((host) => host.protocol !== 'serial' && (allowLocalHosts || host.protocol !== 'local')),
+    [hosts, allowLocalHosts],
   );
   const selectedHostIdSet = useMemo(
     () => new Set(selectedHostIds),

components/SnippetsRightPanel.tsx

@@ -132,6 +132,7 @@ export const SnippetsRightPanel: React.FC<SnippetsRightPanelProps> = ({
           customGroups={customGroups}
           selectedHostIds={targetSelection}
           multiSelect={true}
+          allowLocalHosts={true}
           onSelect={handleTargetSelect}
           onSelectionChange={handleTargetSelectionChange}
           onBack={handleTargetPickerBack}

components/TerminalLayer.tsx

@@ -50,6 +50,7 @@ import {
   resolveTerminalChainHosts,
   resolveTerminalSessionHost,
 } from '../domain/terminalHostResolution';
+import { useDefaultLocalShellContext } from '../lib/useDiscoveredShells';
 import { Tooltip, TooltipContent, TooltipTrigger } from './ui/tooltip';
 import { toast } from './ui/toast';
 import { useI18n } from '../application/i18n/I18nProvider';
@@ -182,7 +183,7 @@ function buildScriptSessionMeta(
     connected: session.status === 'connected',
     name: session.customName || session.hostLabel || host?.label,
     hostname: host?.hostname ?? session.hostname,
-    username: host?.username ?? session.username,
+    username: session.protocol === 'local' ? session.username : host?.username ?? session.username,
   };
 }
 
@@ -1195,14 +1196,16 @@ const TerminalLayerInner: React.FC<TerminalLayerProps> = ({
     () => new Set(proxyProfiles.map((profile) => profile.id)),
     [proxyProfiles],
   );
+  const defaultLocalShell = useDefaultLocalShellContext(terminalSettings);
   const effectiveHosts = useMemo(
     () => hosts.map((host) => resolveEffectiveTerminalHost({
       host,
       groupConfigs,
       proxyProfiles,
       validProxyProfileIds: proxyProfileIdSet,
+      defaultLocalShell,
     })),
-    [groupConfigs, hosts, proxyProfileIdSet, proxyProfiles],
+    [groupConfigs, hosts, proxyProfileIdSet, proxyProfiles, defaultLocalShell],
   );
 
   // Pre-compute fallback hosts to avoid creating new objects on every render
@@ -1215,11 +1218,12 @@ const TerminalLayerInner: React.FC<TerminalLayerProps> = ({
         groupConfigs,
         proxyProfiles,
         localOs: detectLocalOs(navigator.userAgent || navigator.platform),
+        defaultLocalShell,
       });
       map.set(session.id, applySessionFontSizeToHost(hostForSession, session));
     }
     return map;
-  }, [sessions, hosts, groupConfigs, proxyProfiles]);
+  }, [sessions, hosts, groupConfigs, proxyProfiles, defaultLocalShell]);
   const resolvedSessionHostIds = useMemo(() => {
     const ids = new Set<string>();
     for (const session of sessions) {

components/TerminalPopupPage.test.ts

@@ -5,6 +5,7 @@ import { readFileSync } from 'node:fs';
 import type { Host, TerminalSession } from '../types';
 import type { TerminalPopupPayload } from '../domain/systemManager/types';
 import { resolveTerminalPopupHost, resolveTerminalPopupReuseId } from './TerminalPopupPage';
+import { resolveShellSetting } from '../lib/useDiscoveredShells';
 
 const source = readFileSync(new URL('./TerminalPopupPage.tsx', import.meta.url), 'utf8');
 const terminalSource = readFileSync(new URL('./Terminal.tsx', import.meta.url), 'utf8');
@@ -53,6 +54,36 @@ test('resolveTerminalPopupHost honors source session transport over saved Mosh h
   assert.equal(host.etEnabled, false);
 });
 
+test('resolveTerminalPopupHost resolves the settings shell for saved local hosts with a system default shell', () => {
+  const localHost = vaultHost({
+    protocol: 'local',
+    hostname: 'localhost',
+    username: '',
+    port: undefined,
+    localShell: undefined,
+  });
+  const defaultLocalShell = {
+    discoveredShells: [],
+    resolveShellSetting,
+    terminalSettings: { localShell: 'fish', localShellArgs: [] },
+  };
+
+  const withContext = resolveTerminalPopupHost(
+    popupPayload(sourceSession({ protocol: 'local', port: undefined })),
+    [localHost],
+    { defaultLocalShell },
+  );
+  assert.equal(withContext.localShell, 'fish');
+
+  // Without the context (e.g. callers that cannot resolve it) the vault host
+  // keeps its saved (empty) shell — the caller decides how to handle it.
+  const withoutContext = resolveTerminalPopupHost(
+    popupPayload(sourceSession({ protocol: 'local', port: undefined })),
+    [localHost],
+  );
+  assert.equal(withoutContext.localShell, undefined);
+});
+
 test('resolveTerminalPopupHost still falls back to source session details when the host is missing', () => {
   const host = resolveTerminalPopupHost(popupPayload(sourceSession({ hostId: 'missing' })), []);
 

components/TerminalPopupPage.tsx

@@ -12,12 +12,14 @@ import {
 } from '../application/state/resolveTerminalSessionExitIntent';
 import { upsertKnownHost } from '../domain/knownHosts';
 import { isPluginHostProtocol, sanitizePluginConnection } from '../domain/pluginConnection';
+import type { ResolveDefaultLocalShellContext } from '../domain/localShellHost';
 import { resolveTerminalChainHosts, resolveTerminalSessionHost } from '../domain/terminalHostResolution';
 import type { TerminalPopupPayload } from '../domain/systemManager/types';
 import type { GroupConfig, Host, ProxyProfile, TerminalTheme } from '../domain/models';
 import type { KnownHost } from '../types';
 import { getEffectiveKnownHosts } from '../infrastructure/syncHelpers';
 import { detectLocalOs } from '../lib/localShell';
+import { useDefaultLocalShellContext } from '../lib/useDiscoveredShells';
 import { cn } from '../lib/utils';
 import type { AppLockGateRenderContext } from './AppLockGate';
 import { PluginAuthenticationHost } from './plugins/PluginAuthenticationHost';
@@ -233,6 +235,7 @@ export function resolveTerminalPopupHost(
     groupConfigs?: GroupConfig[];
     proxyProfiles?: ProxyProfile[];
     localOs?: Host['os'];
+    defaultLocalShell?: ResolveDefaultLocalShellContext;
   } = {},
 ): Host {
   const resolvedHost = resolveTerminalSessionHost({
@@ -241,6 +244,7 @@ export function resolveTerminalPopupHost(
     groupConfigs: options.groupConfigs ?? [],
     proxyProfiles: options.proxyProfiles ?? [],
     localOs: options.localOs ?? 'linux',
+    defaultLocalShell: options.defaultLocalShell,
   });
   return applySourceSessionConnectionOverrides(
     resolvedHost,
@@ -366,14 +370,17 @@ function TerminalPopupPageInner({
     });
   }, [attachAuthorization, attachSessionId, handleClose, onPrepareClose]);
 
+  const defaultLocalShell = useDefaultLocalShellContext(settings.terminalSettings);
+
   const host = useMemo(() => {
     if (!config) return null;
     return resolveTerminalPopupHost(config, hosts, {
       groupConfigs,
       proxyProfiles,
       localOs: detectLocalOs(navigator.userAgent || navigator.platform),
+      defaultLocalShell,
     });
-  }, [config, groupConfigs, hosts, proxyProfiles]);
+  }, [config, groupConfigs, hosts, proxyProfiles, defaultLocalShell]);
 
   const chainHosts = useMemo(() => resolveTerminalChainHosts({
     host,

components/VaultView.localShellSave.test.ts

@@ -0,0 +1,111 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import ts from "typescript";
+import { upsertHostById } from "../domain/host";
+import { saveWorkSurfaceHostDraft } from "../application/state/useWorkSurfaceHostEditor";
+import { createLocalShellHost } from "../domain/localShellHost";
+import type { Host } from "../types";
+
+// Execute the actual Vault save callback with its persistence boundary stubbed.
+const source = readFileSync(new URL("./VaultView.tsx", import.meta.url), "utf8");
+const callback = source.match(/const handleSaveLocalShellHost = useCallback\((\(host: Host, connectNow\?: boolean\) => \{[\s\S]*?)\}, \[/)?.[1];
+assert.ok(callback);
+const compiled = ts.transpile(`const save = ${callback}};`, { target: ts.ScriptTarget.ES2022 });
+
+for (const editing of [false, true]) {
+  for (const connectNow of [false, true]) {
+    test(`local shell save: editing=${editing}, connect=${connectNow}`, () => {
+      const opened = createLocalShellHost({ id: "local-1", label: "old", tags: ["old"], notes: "clear me" });
+      const latest = { ...opened, showLineTimestamps: true, lastConnectedAt: 42 };
+      const draft = { ...opened, tags: ["edited"], notes: undefined };
+      let saved: Host[] = [];
+      let connected: Host | undefined;
+      // Mirror useVaultState.updateHosts: hostsRef holds the freshest host
+      // array and accepts an array or functional updater argument.
+      const hostsRef: { current: Host[] } = { current: editing ? [latest] : [] };
+      const save = new Function(
+        "hosts", "editingLocalShellHost", "onUpdateHosts", "onConnect",
+        "setIsLocalShellHostPanelOpen", "setEditingLocalShellHost",
+        "upsertHostById", "saveWorkSurfaceHostDraft",
+        `${compiled} return save;`,
+      )(
+        editing ? [latest] : [], editing ? opened : null,
+        (data: Host[] | ((prev: Host[]) => Host[])) => {
+          const next = typeof data === "function" ? data(hostsRef.current) : data;
+          if (next) hostsRef.current = next;
+          saved = next ?? hostsRef.current;
+        },
+        (host: Host) => { connected = host; },
+        () => {}, () => {}, upsertHostById, saveWorkSurfaceHostDraft,
+      );
+      save(draft, connectNow);
+      assert.equal(saved.length, 1);
+      assert.deepEqual(saved[0], editing ? { ...latest, tags: ["edited"], notes: undefined } : draft);
+      assert.deepEqual(connected, connectNow ? saved[0] : undefined);
+    });
+  }
+}
+
+// Saving must apply the draft against the freshest host array, not the array
+// captured at render time — a concurrent vault write between render and Save
+// would otherwise be replaced wholesale by the stale snapshot.
+test("local shell save: updater merges against the latest host array", () => {
+  const opened = createLocalShellHost({ id: "local-1", label: "old", tags: ["old"] });
+  const draft = { ...opened, tags: ["edited"] };
+  // A concurrent write lands after the render that captured `hosts`.
+  const concurrent = createLocalShellHost({ id: "local-2", label: "later" });
+  const renderedHosts = [opened];
+  const actualHosts = [...renderedHosts, concurrent];
+  // Mirror useVaultState.updateHosts: hostsRef holds the freshest host array
+  // (including the concurrent write) and accepts an array or updater argument.
+  let saved: Host[] = [];
+  const hostsRef: { current: Host[] } = { current: actualHosts };
+  const save = new Function(
+    "hosts", "editingLocalShellHost", "onUpdateHosts", "onConnect",
+    "setIsLocalShellHostPanelOpen", "setEditingLocalShellHost",
+    "upsertHostById", "saveWorkSurfaceHostDraft",
+    `${compiled} return save;`,
+  )(
+    renderedHosts, opened,
+    (data: Host[] | ((prev: Host[]) => Host[])) => {
+      const next = typeof data === "function" ? data(hostsRef.current) : data;
+      if (next) hostsRef.current = next;
+      saved = next ?? hostsRef.current;
+    },
+    () => {}, () => {}, () => {}, upsertHostById, saveWorkSurfaceHostDraft,
+  );
+  save(draft, false);
+  assert.equal(saved.length, 2, "concurrently added host must survive the save");
+  assert.ok(saved.some((host) => host.id === "local-2"));
+  assert.ok(saved.some((host) => host.id === "local-1" && host.tags.includes("edited")));
+});
+
+// Duplicating a local-shell host opens its copy under a newly generated ID
+// that is not in the vault yet; it must be saved as a new entry, not as an
+// edit (which would no-op and silently discard the duplicate).
+test("local shell save: duplicated host with a new id saves as a new entry", () => {
+  const opened = createLocalShellHost({ label: "cmd (copy)" });
+  const draft = { ...opened, notes: "tweaked" };
+  let saved: Host[] = [];
+  let connected: Host | undefined;
+  const save = new Function(
+    "hosts", "editingLocalShellHost", "onUpdateHosts", "onConnect",
+    "setIsLocalShellHostPanelOpen", "setEditingLocalShellHost",
+    "upsertHostById", "saveWorkSurfaceHostDraft",
+    `${compiled} return save;`,
+  )(
+    [], opened,
+    // Mirror useVaultState.updateHosts: accepts an array or a functional
+    // updater applied against the freshest host array (here, the vault is
+    // empty at render time and stays empty in prev too).
+    (data: Host[] | ((prev: Host[]) => Host[])) => { saved = typeof data === "function" ? data(saved) : data; },
+    (host: Host) => { connected = host; },
+    () => {}, () => {}, upsertHostById, saveWorkSurfaceHostDraft,
+  );
+  save(draft, false);
+  assert.equal(saved.length, 1);
+  assert.equal(saved[0].id, draft.id);
+  assert.equal(saved[0].notes, "tweaked");
+  assert.equal(connected, undefined);
+});

components/VaultView.tsx

@@ -73,6 +73,7 @@ import {
   upsertHostById,
 } from "../domain/host";
 import { exportHostsToCsvWithStats } from "../domain/vaultImport";
+import { saveWorkSurfaceHostDraft, type WorkSurfaceHostEditorTarget } from "../application/state/useWorkSurfaceHostEditor";
 import { upsertKnownHost } from "../domain/knownHosts";
 import {
   remapSnippetTargetGroupPaths,
@@ -238,7 +239,9 @@ interface VaultViewProps {
   onDeleteHost: (id: string) => void;
   onConnect: (host: Host) => void;
   onOpenHostFromNote?: (host: Host, source?: { noteId: string }) => void;
-  onUpdateHosts: (hosts: Host[]) => VaultHostPersistenceResult | Promise<VaultHostPersistenceResult>;
+  onUpdateHosts: (
+    hosts: Host[] | ((prev: Host[]) => Host[]),
+  ) => VaultHostPersistenceResult | Promise<VaultHostPersistenceResult>;
   onReadPersistedHosts: () => Promise<Host[]>;
   onUpdateKeys: (keys: SSHKey[]) => void;
   onImportOrReuseKey: (draft: Partial<SSHKey>) => SSHKey;
@@ -458,6 +461,9 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
   const [isHostPanelOpen, setIsHostPanelOpen] = useState(false);
   const [editingHost, setEditingHost] = useState<Host | null>(null);
   const [newHostGroupPath, setNewHostGroupPath] = useState<string | null>(null);
+  // Local shell (CMD) host panel state — a vault host entry with protocol 'local'
+  const [isLocalShellHostPanelOpen, setIsLocalShellHostPanelOpen] = useState(false);
+  const [editingLocalShellHost, setEditingLocalShellHost] = useState<Host | null>(null);
   const [pendingOpenNoteId, setPendingOpenNoteId] = useState<string | null>(
     null,
   );
@@ -473,8 +479,17 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
     setCurrentSection("hosts");
     setSelectedGroupPath(null);
     setNewHostGroupPath(null);
-    setEditingHost(deepLinkHostDraft);
-    setIsHostPanelOpen(true);
+    if (deepLinkHostDraft.protocol === "local") {
+      setEditingHost(null);
+      setIsHostPanelOpen(false);
+      setEditingLocalShellHost(deepLinkHostDraft);
+      setIsLocalShellHostPanelOpen(true);
+    } else {
+      setIsLocalShellHostPanelOpen(false);
+      setEditingLocalShellHost(null);
+      setEditingHost(deepLinkHostDraft);
+      setIsHostPanelOpen(true);
+    }
     onDeepLinkHostDraftHandled?.();
   }, [deepLinkHostDraft, onDeepLinkHostDraftHandled]);
 
@@ -507,17 +522,17 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
   useEffect(() => {
     const currentIds = new Set(hosts.map((h) => h.id));
     // Check against previous IDs before updating the ref
-    if (
-      editingHost &&
-      knownHostIdsRef.current.has(editingHost.id) &&
-      !currentIds.has(editingHost.id)
-    ) {
+    const editingDeleted = (openHost: Host | null) =>
+      Boolean(openHost && knownHostIdsRef.current.has(openHost.id) && !currentIds.has(openHost.id));
+    if (editingDeleted(editingHost) || editingDeleted(editingLocalShellHost)) {
       setIsHostPanelOpen(false);
       setEditingHost(null);
+      setIsLocalShellHostPanelOpen(false);
+      setEditingLocalShellHost(null);
       setNewHostGroupPath(null);
     }
     knownHostIdsRef.current = currentIds;
-  }, [hosts, editingHost]);
+  }, [hosts, editingHost, editingLocalShellHost]);
 
   // Group panel state
   const [isGroupPanelOpen, setIsGroupPanelOpen] = useState(false);
@@ -599,8 +614,12 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
             {},
             { validProxyProfileIds: proxyProfileIdSet },
           );
-      // Only prompt when Telnet is available but isn't the host's default protocol.
-      if (effective.telnetEnabled && effective.protocol !== "telnet") {
+      // Only prompt when Telnet is available but isn't the host's default
+      // protocol, and only for SSH hosts: local-shell and serial hosts must
+      // always launch their own transport, never an inherited group Telnet
+      // flag. Hosts without an explicit protocol are legacy SSH entries.
+      const effectiveProtocol = effective.protocol ?? "ssh";
+      if (effectiveProtocol === "ssh" && effective.telnetEnabled) {
         setProtocolSelectHost(effective);
       } else if (effective.protocol === "telnet") {
         // Telnet-as-default wins over a stray moshEnabled flag.
@@ -654,13 +673,67 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
     setIsGroupPanelOpen(false);
     setEditingGroupPath(null);
     setEditingHost(null);
+    setIsLocalShellHostPanelOpen(false);
+    setEditingLocalShellHost(null);
     setNewHostGroupPath(null);
     setIsHostPanelOpen(true);
   }, []);
 
+  // "Local shell (CMD)" entry under the New Host menu — opens the dedicated
+  // local-shell host editor with the current vault group preselected.
+  const handleNewLocalShellHost = useCallback(() => {
+    setIsGroupPanelOpen(false);
+    setEditingGroupPath(null);
+    setEditingHost(null);
+    setIsHostPanelOpen(false);
+    setEditingLocalShellHost(null);
+    setNewHostGroupPath(null);
+    setIsLocalShellHostPanelOpen(true);
+  }, []);
+
+  const handleCancelLocalShellHost = useCallback(() => {
+    setIsLocalShellHostPanelOpen(false);
+    setEditingLocalShellHost(null);
+  }, []);
+
+  const handleSaveLocalShellHost = useCallback((host: Host, connectNow?: boolean) => {
+    // A duplicated local host carries a freshly generated ID that is not in the
+    // vault yet, so it must be saved as a new entry (edit mode would no-op).
+    // (Note: the mode is derived from the rendered hosts snapshot only, so the
+    // updater below can still merge against the up-to-date vault array.)
+    const editingExistingHost = hosts.some((entry) => entry.id === editingLocalShellHost?.id);
+    const target: WorkSurfaceHostEditorTarget = editingExistingHost && editingLocalShellHost
+      ? { mode: "edit", openedHost: editingLocalShellHost, requestId: 0 }
+      : { mode: "new", defaultGroup: null, requestId: 0 };
+    // Apply the draft against the freshest host array, not the one captured at
+    // render time: another vault write (terminal metadata, sync) may have
+    // updated hostsRef between render and Save, and submitting the captured
+    // array would replace it wholesale.
+    let savedHost: Host | null = null;
+    onUpdateHosts((prevHosts) => {
+      const updatedHosts = saveWorkSurfaceHostDraft(prevHosts, target, host);
+      if (!updatedHosts) return prevHosts;
+      savedHost = updatedHosts.find((entry) => entry.id === host.id) ?? null;
+      return updatedHosts;
+    });
+    setIsLocalShellHostPanelOpen(false);
+    setEditingLocalShellHost(null);
+    if (connectNow && savedHost) onConnect(savedHost);
+  }, [hosts, editingLocalShellHost, onConnect, onUpdateHosts]);
+
   const handleEditHost = useCallback((host: Host) => {
     setIsGroupPanelOpen(false);
     setEditingGroupPath(null);
+    // Local shell hosts route to their dedicated editor (no SSH auth fields).
+    if (host.protocol === "local") {
+      setEditingHost(null);
+      setIsHostPanelOpen(false);
+      setEditingLocalShellHost(host);
+      setIsLocalShellHostPanelOpen(true);
+      return;
+    }
+    setIsLocalShellHostPanelOpen(false);
+    setEditingLocalShellHost(null);
     setEditingHost(host);
     setIsHostPanelOpen(true);
   }, []);
@@ -687,6 +760,15 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
         lastConnectedAt: undefined,
       };
       // Open the edit panel with the duplicated host for modification
+      if (duplicatedHost.protocol === "local") {
+        setEditingHost(null);
+        setIsHostPanelOpen(false);
+        setEditingLocalShellHost(duplicatedHost);
+        setIsLocalShellHostPanelOpen(true);
+        return;
+      }
+      setEditingLocalShellHost(null);
+      setIsLocalShellHostPanelOpen(false);
       setEditingHost(duplicatedHost);
       setIsHostPanelOpen(true);
     },
@@ -1276,6 +1358,7 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
     handleUnmanageGroup,
     managedGroupPaths,
     moveHostToGroup,
+    moveHostsToGroup,
     setDragOverDropTarget,
     setGroupDragOverDropTarget,
   } = useVaultGroupDragHandlers({
@@ -1355,7 +1438,9 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
   const isHostsSectionActive = currentSection === "hosts";
   const hasHostsSidePanel =
     isHostsSectionActive &&
-    ((isGroupPanelOpen && !!editingGroupPath) || isHostPanelOpen);
+    ((isGroupPanelOpen && !!editingGroupPath)
+      || isHostPanelOpen
+      || isLocalShellHostPanelOpen);
   // Every host grid uses the same container-based fixed column count. This keeps
   // pinned/recent cards aligned with the virtualized main grid and prevents a
   // single card from stretching across the full row.
@@ -1469,6 +1554,9 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
           handleHostConnect,
           handleImportFileSelected,
           handleNewHost,
+          handleNewLocalShellHost,
+          handleCancelLocalShellHost,
+          handleSaveLocalShellHost,
           handleProtocolSelect,
           handleQuickConnect,
           handleQuickConnectSaveHost,
@@ -1488,6 +1576,8 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
           isDeleteGroupOpen,
           isGroupPanelOpen,
           isHostPanelOpen,
+          isLocalShellHostPanelOpen,
+          editingLocalShellHost,
           isHostsSectionActive,
           isImportOpen,
           isMultiSelectMode,
@@ -1513,6 +1603,7 @@ const VaultViewInner: React.FC<VaultViewProps> = ({
           managedSources,
           moveGroup,
           moveHostToGroup,
+          moveHostsToGroup,
           Network,
           newFolderName,
           newHostGroupPath,

components/VaultViewLayout.test.ts

@@ -20,8 +20,10 @@ test("vault header collapsed actions cannot retain hidden focus", () => {
   assert.match(vaultViewLayoutSource, /newHostActionsRef\.current\?\.contains\(activeElement\)/);
   assert.match(vaultViewLayoutSource, /sessionActionsRef\.current\?\.contains\(activeElement\)/);
   assert.match(vaultViewLayoutSource, /activeElement\.blur\(\)/);
-  assert.match(vaultViewLayoutSource, /aria-hidden=\{isHostPanelOpen \? true : undefined\}/);
-  assert.match(vaultViewLayoutSource, /inert=\{isHostPanelOpen \? true : undefined\}/);
+  // Both the SSH/new-host panel and the local-shell host panel collapse the
+  // header actions so hidden buttons cannot retain focus.
+  assert.match(vaultViewLayoutSource, /aria-hidden=\{isHostAsideOpen \? true : undefined\}/);
+  assert.match(vaultViewLayoutSource, /inert=\{isHostAsideOpen \? true : undefined\}/);
 });
 
 test("vault sidebar toggle keeps an accessible action label", () => {

components/ai/ChatMessageList.test.tsx

@@ -585,3 +585,20 @@ test("Codex approval render plan preserves every approval for the same item", ()
     ["approval-3"],
   );
 });
+
+test('fork is offered only for safe completed replies and hidden while streaming', () => {
+  const messages: ChatMessage[] = [
+    { id: 'u', role: 'user', content: 'hello', timestamp: 1 },
+    { id: 'done', role: 'assistant', content: 'completed', timestamp: 2, executionStatus: 'completed' },
+    { id: 'failed', role: 'assistant', content: 'failed', timestamp: 3, executionStatus: 'failed' },
+  ];
+  const render = (isStreaming: boolean) => renderToStaticMarkup(
+    <I18nProvider locale="en">
+      <TooltipProvider>
+        <ChatMessageList messages={messages} isStreaming={isStreaming} onForkFromMessage={() => {}} />
+      </TooltipProvider>
+    </I18nProvider>,
+  );
+  assert.equal((render(false).match(/Fork from here/g) ?? []).length, 1);
+  assert.equal((render(true).match(/Fork from here/g) ?? []).length, 0);
+});

components/ai/ChatMessageList.tsx

@@ -6,10 +6,11 @@
  * No avatars. Thinking blocks are collapsible.
  */
 
-import { AlertCircle, BookOpen, FileText, RotateCcw, SquareTerminal, X, ZoomIn, ZoomOut } from 'lucide-react';
+import { AlertCircle, BookOpen, FileText, GitFork, RotateCcw, SquareTerminal, X, ZoomIn, ZoomOut } from 'lucide-react';
 import React, { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import { useI18n } from '../../application/i18n/I18nProvider';
-import type { ChatMessage, ToolCall as AgentToolCall } from '../../infrastructure/ai/types';
+import type { AISessionContextCompaction, ChatMessage, ToolCall as AgentToolCall } from '../../infrastructure/ai/types';
+import { getForkableMessageIds } from '../../domain/aiSessionFork';
 import { Dialog, DialogContent, DialogTitle } from '../ui/dialog';
 import {
   Conversation,
@@ -92,6 +93,10 @@ interface ChatMessageListProps {
   /** Active chat session ID — used to filter standalone MCP approval blocks */
   activeSessionId?: string | null;
   activeCompaction?: ActiveCompactionUi | null;
+  /** Stored compaction summary for the viewed session — fork boundaries must not fall inside its coverage. */
+  contextCompaction?: AISessionContextCompaction | null;
+  /** Present when the panel supports forking a conversation from a completed assistant response. */
+  onForkFromMessage?: (messageId: string) => void;
   notes?: VaultNote[];
   hosts?: Host[];
   snippets?: Snippet[];
@@ -160,6 +165,8 @@ export function buildCodexApprovalRenderPlan(
 const MESSAGE_RENDER_BATCH = 50;
 const MESSAGE_RENDER_STEP = 50;
 
+const EMPTY_FORKABLE_SET: ReadonlySet<string> = new Set();
+
 export function pruneResolvedApprovals(
   previous: ReadonlyMap<string, boolean>,
   messages: readonly ChatMessage[],
@@ -180,6 +187,8 @@ const ChatMessageList: React.FC<ChatMessageListProps> = ({
   isStreaming,
   activeSessionId,
   activeCompaction = null,
+  contextCompaction,
+  onForkFromMessage,
   notes = [],
   hosts = [],
   snippets = [],
@@ -399,6 +408,14 @@ const ChatMessageList: React.FC<ChatMessageListProps> = ({
     [messages],
   );
 
+  // "Fork from here" targets: completed assistant responses whose whole
+  // prefix is a safe fork boundary (fully resolved tool calls, stored
+  // compaction summary still accurate). Hidden entirely while a turn streams.
+  const forkableMessageIds = useMemo(() => {
+    if (!onForkFromMessage || isStreaming) return EMPTY_FORKABLE_SET;
+    return getForkableMessageIds({ messages, contextCompaction: contextCompaction ?? undefined });
+  }, [onForkFromMessage, isStreaming, messages, contextCompaction]);
+
   // While a jump target is active, re-resolve the tail against the current list
   // so streaming appends cannot slide the window past the selected message.
   const effectiveTailCount = activeJumpMessageId
@@ -798,6 +815,22 @@ const ChatMessageList: React.FC<ChatMessageListProps> = ({
                     </div>
                   </div>
                 )}
+
+                {/* Fork from here — copies the conversation up to this completed
+                    response into a new session. Only on safe boundaries; hidden
+                    while a turn streams (forkableMessageIds empty). */}
+                {!isUser && onForkFromMessage && forkableMessageIds.has(message.id) && (
+                  <div className="flex -mt-0.5 opacity-0 group-hover:opacity-100 focus-within:opacity-100">
+                    <button
+                      type="button"
+                      onClick={() => onForkFromMessage(message.id)}
+                      className="flex items-center gap-1 rounded-md px-1.5 py-0.5 text-[11px] text-muted-foreground/40 hover:text-foreground hover:bg-white/[0.05] transition-colors cursor-pointer"
+                    >
+                      <GitFork size={11} />
+                      <span>{t('ai.chat.forkFromHere')}</span>
+                    </button>
+                  </div>
+                )}
               </MessageContent>
             </Message>
           );
@@ -1042,6 +1075,8 @@ function areMessagesEqual(prev: ChatMessageListProps, next: ChatMessageListProps
   if (prev.onOpenVaultHost !== next.onOpenVaultHost) return false;
   if (prev.onOpenVaultSnippet !== next.onOpenVaultSnippet) return false;
   if (prev.onOpenVaultSection !== next.onOpenVaultSection) return false;
+  if (prev.onForkFromMessage !== next.onForkFromMessage) return false;
+  if (prev.contextCompaction !== next.contextCompaction) return false;
   if (prev.messages.length !== next.messages.length) return false;
   if (prev.messages === next.messages) return true;
 

components/scripts/ScriptEditorModal.tsx

@@ -200,6 +200,7 @@ export const ScriptEditorModal: React.FC<ScriptEditorModalProps> = ({
         customGroups={customGroups}
         selectedHostIds={selectedHostIds}
         multiSelect
+        allowLocalHosts={true}
         onSelect={onSelectHost}
         onSelectionChange={onSelectionChange}
         onConfirm={handleTargetsConfirm}

components/sftp/SftpHostPicker.tsx

@@ -10,7 +10,7 @@ import {
     sftpSourceSessionIdForHost,
     type SftpConnectedHostEntry,
 } from '../../domain/sftpConnectedHosts';
-import { isPluginHostProtocol } from '../../domain/pluginConnection';
+import { canOpenDualPaneSftp } from '../../domain/sftpDualPaneOpen';
 import { Host } from '../../types';
 import { DistroAvatar } from '../DistroAvatar';
 import { getQuickSwitcherRowStateClass, shouldUseQuickSwitcherPointerNavigation } from '../QuickSwitcher';
@@ -95,9 +95,11 @@ const SftpHostPickerInner: React.FC<SftpHostPickerProps> = ({
 
     const filteredHosts = useMemo(() => {
         return hosts.filter((h) => {
-            // SFTP is an SSH-specific host capability. Plugin protocols may
-            // provide arbitrary transports and cannot be treated as SSH.
-            if (h.protocol === "serial" || isPluginHostProtocol(h.protocol)) return false;
+            // SFTP is an SSH-specific host capability. Reuse the dual-pane
+            // opener's predicate so serial, local-shell (no SSH channel —
+            // selecting one would SSH into localhost) and plugin protocols
+            // are excluded the same way everywhere.
+            if (!canOpenDualPaneSftp(h)) return false;
             // Hide a saved host only when Connected already shows the same endpoint.
             // If the vault host was edited after connect, keep both: Live (old) + Saved (new).
             const connected = connectedByHostId.get(h.id);

components/terminal/runtime/createTerminalSessionStarters.localShellArgs.test.ts

@@ -0,0 +1,104 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { createTerminalSessionStarters } from "./createTerminalSessionStarters";
+
+const noop = () => undefined;
+
+const makeCtx = (
+  host: Record<string, unknown>,
+  startLocalSession: (options: Record<string, unknown>) => Promise<string>,
+) => ({
+  host: {
+    id: "host-1",
+    label: "Local Shell",
+    hostname: "localhost",
+    username: "",
+    protocol: "local",
+    ...host,
+  },
+  keys: [],
+  identities: [],
+  resolvedChainHosts: [],
+  sessionId: "session-1",
+  terminalSettings: {},
+  terminalBackend: {
+    backendAvailable: () => true,
+    telnetAvailable: () => true,
+    moshAvailable: () => true,
+    etAvailable: () => true,
+    localAvailable: () => true,
+    serialAvailable: () => true,
+    execAvailable: () => true,
+    startSSHSession: async () => "ssh-session",
+    startLocalSession,
+    onSessionData: () => noop,
+    onSessionExit: () => noop,
+    writeToSession: noop,
+    resizeSession: noop,
+  },
+  sessionRef: { current: null },
+  hasConnectedRef: { current: true },
+  hasRunStartupCommandRef: { current: false },
+  disposeDataRef: { current: null },
+  disposeExitRef: { current: null },
+  fitAddonRef: { current: null },
+  serializeAddonRef: { current: null },
+  pendingAuthRef: { current: null },
+  updateStatus: noop,
+  setStatus: noop,
+  setError: noop,
+  setNeedsAuth: noop,
+  setAuthRetryMessage: noop,
+  setAuthPassword: noop,
+  setProgressLogs: noop,
+  setProgressValue: noop,
+  setChainProgress: noop,
+});
+
+const term = {
+  cols: 120,
+  rows: 32,
+  write: noop,
+  writeln: noop,
+  scrollToBottom: noop,
+};
+
+test("startLocal omits an empty no-args snapshot so backend defaults apply", async () => {
+  // Vault local hosts snapshot absent args as [] to keep launch-time no-args
+  // semantics for clone/popup relaunch, but the snapshot must not be passed to
+  // the bridge: an empty array is truthy and would suppress the bridge's
+  // discovered-shell args and getLocalShellArgs fallbacks (login flags,
+  // PowerShell -NoLogo).
+  let started: Record<string, unknown> | null = null;
+  const ctx = makeCtx(
+    { localShell: "fish", localShellArgs: [] },
+    async (options) => {
+      started = options;
+      return "local-session";
+    },
+  );
+
+  await createTerminalSessionStarters(ctx as never).startLocal(term as never);
+
+  assert.ok(started);
+  assert.equal((started as { shell?: string }).shell, "fish");
+  assert.equal((started as { shellArgs?: string[] }).shellArgs, undefined);
+});
+
+test("startLocal passes explicit local shell args through", async () => {
+  let started: Record<string, unknown> | null = null;
+  const ctx = makeCtx(
+    { localShell: "bash", localShellArgs: ["--login", "-i"] },
+    async (options) => {
+      started = options;
+      return "local-session";
+    },
+  );
+
+  await createTerminalSessionStarters(ctx as never).startLocal(term as never);
+
+  assert.ok(started);
+  assert.equal((started as { shell?: string }).shell, "bash");
+  assert.deepEqual((started as { shellArgs?: string[] }).shellArgs, ["--login", "-i"]);
+});

components/terminal/runtime/createTerminalSessionStarters.test.ts

@@ -3653,7 +3653,13 @@ test("restored local reconnect runs the host startup command while automatic ret
   assert.deepEqual(sessionWrites, []);
 });
 
-test("local session start uses per-session directory before global default", async () => {
+for (const { name, hostDirectory, globalDirectory, expectedDirectory } of [
+  { name: "uses saved directory before global default", hostDirectory: "/Users/alice/project", globalDirectory: "/Users/alice/default", expectedDirectory: "/Users/alice/project" },
+  { name: "inherits global directory when unset", hostDirectory: undefined, globalDirectory: "/Users/alice/default", expectedDirectory: "/Users/alice/default" },
+  { name: "inherits global directory when cleared", hostDirectory: "", globalDirectory: "/Users/alice/default", expectedDirectory: "/Users/alice/default" },
+  { name: "leaves directory unset for backend home default", hostDirectory: undefined, globalDirectory: undefined, expectedDirectory: undefined },
+]) {
+test(`local session start ${name}`, async () => {
   let capturedOptions: Record<string, unknown> | null = null;
   const terminalBackend = {
     backendAvailable: () => true,
@@ -3685,16 +3691,17 @@ test("local session start uses per-session directory before global default", asy
       hostname: "local",
       username: "",
       protocol: "local",
-      localStartDir: "/Users/alice/project",
+      localStartDir: hostDirectory,
     },
-    terminalSettings: { localStartDir: "/Users/alice/default" },
+    terminalSettings: { localStartDir: globalDirectory },
     terminalBackend,
   });
 
   await createTerminalSessionStarters(ctx as never).startLocal(createTermStub() as never);
 
-  assert.equal(capturedOptions?.cwd, "/Users/alice/project");
+  assert.equal(capturedOptions?.cwd, expectedDirectory);
 });
+}
 
 test("local session restores cwd before startup command after attaching", async () => {
   const sessionWrites: Array<{ id: string; data: string; automated?: boolean }> = [];

components/terminal/runtime/createTerminalSessionStarters.ts

@@ -1835,8 +1835,14 @@ export const createTerminalSessionStarters = (ctx: TerminalSessionStartersContex
       // which was already resolved to command+args and stored on the session object by App.tsx.
       // Only pass shell/shellArgs when we have concrete per-session values;
       // otherwise omit them so the backend uses its own default shell detection.
+      // An empty array is truthy, so `|| undefined` does not filter it out.
+      // Vault local hosts snapshot absent args as `[]` (to preserve
+      // launch-time no-args semantics for clone/popup relaunch), but the
+      // snapshot must still be omitted here: the bridge only applies its
+      // discovered-shell args and getLocalShellArgs fallbacks when shellArgs
+      // is absent (#1221).
       const sessionShell = ctx.host.localShell;
-      const sessionShellArgs = ctx.host.localShellArgs;
+      const sessionShellArgs = ctx.host.localShellArgs?.length ? ctx.host.localShellArgs : undefined;
       const localStartDir = ctx.host.localStartDir || ctx.terminalSettings?.localStartDir;
 
       const id = await ctx.terminalBackend.startLocalSession({
@@ -1844,7 +1850,7 @@ export const createTerminalSessionStarters = (ctx: TerminalSessionStartersContex
         cols: term.cols,
         rows: term.rows,
         shell: sessionShell || undefined,
-        shellArgs: sessionShellArgs || undefined,
+        shellArgs: sessionShellArgs,
         cwd: localStartDir,
         env: {
           TERM: ctx.terminalSettings?.terminalEmulationType ?? "xterm-256color",

components/terminalLayer/TerminalLayerSupport.tsx

@@ -584,6 +584,7 @@ const AIChatPanelsHostInner: React.FC<AIChatPanelsHostProps> = ({
                     addDraftFiles={aiConfig.addDraftFiles}
                     removeDraftFile={aiConfig.removeDraftFile}
                     createSession={aiConfig.createSession}
+                    undoLastTurnInSession={aiConfig.undoLastTurnInSession}
                     deleteSession={aiConfig.deleteSession}
                     updateSessionTitle={aiConfig.updateSessionTitle}
                     updateSessionExternalSessionId={aiConfig.updateSessionExternalSessionId}
@@ -591,6 +592,7 @@ const AIChatPanelsHostInner: React.FC<AIChatPanelsHostProps> = ({
                     updateLastMessage={aiConfig.updateLastMessage}
                     updateMessageById={aiConfig.updateMessageById}
                     persistContextCompaction={aiConfig.persistContextCompaction}
+                    forkSessionFromMessage={aiConfig.forkSessionFromMessage}
                     providers={aiConfig.providers}
                     activeProviderId={aiConfig.activeProviderId}
                     activeModelId={aiConfig.activeModelId}

components/top-tabs/TopTabItems.tsx

@@ -86,7 +86,7 @@ const SessionTabIcon: React.FC<{
   // Local protocol → shell-specific icon if available, else OS-specific icon
   if (protocol === 'local' || host?.protocol === 'local' || (!protocol && !host)) {
     // Use shell icon from discovery when available
-    const iconId = shellIcon || host?.localShellIcon;
+    const iconId = shellIcon ?? host?.localShellIcon;
     if (iconId) {
       return (
         <img

components/vault/VaultHostListSection.tsx

@@ -27,6 +27,7 @@ import {
 import type { GroupNode, Host } from "../../domain/models";
 import { isPluginHostProtocol } from "../../domain/pluginConnection";
 import { OpenDualPaneSftpMenuItem } from "../host/HostTreeContextMenus";
+import { getVaultHostRowSubtitle } from "../../domain/localShellHost";
 
 type VaultHostListSectionContext = Record<string, any>;
 
@@ -598,7 +599,7 @@ export function VaultHostListSection({ ctx }: { ctx: VaultHostListSectionContext
                                         <HostNotesIndicator notes={safeHost.notes} />
                                       </div>
                                       <div className="text-[11px] text-muted-foreground font-mono truncate leading-4">
-                                        {safeHost.username}@{safeHost.hostname}
+                                        {getVaultHostRowSubtitle(safeHost, { localFallback: t('localShell.subtitle') })}
                                       </div>
                                     </div>
                                     {viewMode === "grid" && renderHostEditButton(host)}
@@ -718,7 +719,7 @@ export function VaultHostListSection({ ctx }: { ctx: VaultHostListSectionContext
                                         <HostNotesIndicator notes={safeHost.notes} />
                                       </div>
                                       <div className="text-[11px] text-muted-foreground font-mono truncate leading-4">
-                                        {safeHost.username}@{safeHost.hostname}
+                                        {getVaultHostRowSubtitle(safeHost, { localFallback: t('localShell.subtitle') })}
                                       </div>
                                     </div>
                                     {viewMode === "grid" && renderHostEditButton(host)}
@@ -1097,7 +1098,7 @@ export function VaultHostListSection({ ctx }: { ctx: VaultHostListSectionContext
                                               <HostNotesIndicator notes={safeHost.notes} />
                                             </div>
                                             <div className="text-[11px] text-muted-foreground font-mono truncate leading-4">
-                                              {safeHost.username}@{safeHost.hostname}
+                                              {getVaultHostRowSubtitle(safeHost, { localFallback: t('localShell.subtitle') })}
                                             </div>
                                           </div>
                                           {viewMode === "grid" && renderHostEditButton(host)}
@@ -1247,7 +1248,7 @@ export function VaultHostListSection({ ctx }: { ctx: VaultHostListSectionContext
                                         <HostNotesIndicator notes={safeHost.notes} />
                                       </div>
                                       <div className="text-[11px] text-muted-foreground font-mono truncate leading-4">
-                                        {safeHost.username}@{safeHost.hostname}
+                                        {getVaultHostRowSubtitle(safeHost, { localFallback: t('localShell.subtitle') })}
                                       </div>
                                     </div>
                                     {viewMode === "grid" && renderHostEditButton(host)}

components/vault/VaultViewLayout.tsx

@@ -1,4 +1,5 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
+import { Combobox } from "../ui/combobox";
 import React, { useCallback } from "react";
 import { deleteVaultKey } from "../../application/defaultKeyPassphrases";
 import { VaultGroupDeletionConfirmationChangedError } from "../../application/state/useVaultGroupDeletion";
@@ -12,6 +13,7 @@ import {
 } from "../../domain/vaultGroupSelection";
 import { STORAGE_KEY_VAULT_HOST_PANEL_WIDTH } from "@/infrastructure/config/storageKeys.ts";
 import { VaultHostListSection } from "./VaultHostListSection";
+import { LocalShellHostDetailsPanel } from "../LocalShellHostDetailsPanel";
 import { VaultImportProgressPanel } from "./ImportVaultDialog";
 import {
   VaultHeaderSearch,
@@ -172,6 +174,7 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
     Edit2,
     editingGroupPath,
     editingHost,
+    editingLocalShellHost,
     editingHostGroupDefaults,
     FileCode,
     FileSymlink,
@@ -195,6 +198,9 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
     handleHostConnect,
     handleImportFileSelected,
     handleNewHost,
+    handleNewLocalShellHost,
+    handleCancelLocalShellHost,
+    handleSaveLocalShellHost,
     handleProtocolSelect,
     handleQuickConnect,
     handleQuickConnectSaveHost,
@@ -214,6 +220,7 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
     isDeleteGroupOpen,
     isGroupPanelOpen,
     isHostPanelOpen,
+    isLocalShellHostPanelOpen,
     isHostsSectionActive,
     isImportOpen,
     isMultiSelectMode,
@@ -237,6 +244,7 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
     managedSources,
     moveGroup,
     moveHostToGroup,
+    moveHostsToGroup,
     Network,
     newFolderName,
     newHostGroupPath,
@@ -380,6 +388,9 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
   } = ctx;
   const { importProgress, onCommitPluginImporterData, resetImportProgress } =
     ctx;
+  // Host aside panel (SSH/new host) or the local-shell host panel occupies the
+  // aside area — both collapse the header action buttons the same way.
+  const isHostAsideOpen = isHostPanelOpen || isLocalShellHostPanelOpen;
   const pendingDeleteGroupPaths =
     bulkDeleteGroupPaths.length > 0
       ? bulkDeleteGroupPaths
@@ -436,6 +447,8 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
     persistWidthStorageKey: STORAGE_KEY_VAULT_HOST_PANEL_WIDTH,
     resizeAriaLabel: t("vault.panel.resizeWidth"),
   };
+  const [isMoveHostsOpen, setIsMoveHostsOpen] = React.useState(false);
+  const [moveTargetGroup, setMoveTargetGroup] = React.useState("");
   const [isSidebarResizing, setIsSidebarResizing] = React.useState(false);
   const keyListRef = React.useRef(keys);
   keyListRef.current = keys;
@@ -521,7 +534,7 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
   );
 
   React.useEffect(() => {
-    if (!isHostPanelOpen) return;
+    if (!isHostAsideOpen) return;
     const activeElement = document.activeElement;
     if (!(activeElement instanceof HTMLElement)) return;
     if (
@@ -530,7 +543,7 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
     ) {
       activeElement.blur();
     }
-  }, [isHostPanelOpen]);
+  }, [isHostAsideOpen]);
 
   return (
     <div
@@ -961,12 +974,12 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
                 ref={newHostActionsRef}
                 className={cn(
                   "flex items-center app-no-drag overflow-hidden transition-[max-width,opacity,margin] duration-200 ease-in-out",
-                  isHostPanelOpen
+                  isHostAsideOpen
                     ? "max-w-0 opacity-0 -ml-2 pointer-events-none"
                     : "max-w-[260px] opacity-100",
                 )}
-                aria-hidden={isHostPanelOpen ? true : undefined}
-                inert={isHostPanelOpen ? true : undefined}
+                aria-hidden={isHostAsideOpen ? true : undefined}
+                inert={isHostAsideOpen ? true : undefined}
               >
                 <Dropdown>
                   <div className="flex items-center rounded-md bg-primary text-primary-foreground">
@@ -974,7 +987,7 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
                       size="sm"
                       className="h-10 px-3 rounded-r-none bg-transparent hover:bg-white/10 shadow-none"
                       onClick={handleNewHost}
-                      tabIndex={isHostPanelOpen ? -1 : 0}
+                      tabIndex={isHostAsideOpen ? -1 : 0}
                     >
                       <Plus size={14} className="mr-2" />{" "}
                       {t("vault.hosts.newHost")}
@@ -983,13 +996,20 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
                       <Button
                         size="sm"
                         className="h-10 px-2 rounded-l-none bg-transparent hover:bg-white/10 border-l border-primary-foreground/20 shadow-none"
-                        tabIndex={isHostPanelOpen ? -1 : 0}
+                        tabIndex={isHostAsideOpen ? -1 : 0}
                       >
                         <ChevronDown size={14} />
                       </Button>
                     </DropdownTrigger>
                   </div>
                   <DropdownContent className="w-44" align="end" alignToParent>
+                    <Button
+                      variant="ghost"
+                      className="w-full justify-start gap-2"
+                      onClick={handleNewLocalShellHost}
+                    >
+                      <TerminalSquare size={14} /> {t("vault.hosts.newLocalShell")}
+                    </Button>
                     <Button
                       variant="ghost"
                       className="w-full justify-start gap-2"
@@ -1029,19 +1049,19 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
                 ref={sessionActionsRef}
                 className={cn(
                   "flex items-center gap-3 overflow-hidden transition-[max-width,opacity,margin] duration-200 ease-in-out",
-                  isHostPanelOpen
+                  isHostAsideOpen
                     ? "max-w-0 opacity-0 -ml-3 pointer-events-none"
                     : "max-w-[320px] opacity-100",
                 )}
-                aria-hidden={isHostPanelOpen ? true : undefined}
-                inert={isHostPanelOpen ? true : undefined}
+                aria-hidden={isHostAsideOpen ? true : undefined}
+                inert={isHostAsideOpen ? true : undefined}
               >
                 <Button
                   size="sm"
                   variant="secondary"
                   className={vaultHeaderSecondaryButtonClass}
                   onClick={onCreateLocalTerminal}
-                  tabIndex={isHostPanelOpen ? -1 : 0}
+                  tabIndex={isHostAsideOpen ? -1 : 0}
                 >
                   <TerminalSquare size={14} className="mr-2" />{" "}
                   {t("common.terminal")}
@@ -1051,7 +1071,7 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
                   variant="secondary"
                   className={vaultHeaderSecondaryButtonClass}
                   onClick={() => setIsSerialModalOpen(true)}
-                  tabIndex={isHostPanelOpen ? -1 : 0}
+                  tabIndex={isHostAsideOpen ? -1 : 0}
                 >
                   <Usb size={14} className="mr-2" /> {t("serial.button")}
                 </Button>
@@ -1114,6 +1134,19 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
                     count: selectedHostIds.size,
                   })}
                 </Button>
+                <Button
+                  variant="secondary"
+                  size="sm"
+                  className="h-7 px-2 text-xs"
+                  disabled={selectedHostIds.size === 0}
+                  onClick={() => {
+                    setMoveTargetGroup("");
+                    setIsMoveHostsOpen(true);
+                  }}
+                >
+                  <FolderTree size={12} className="mr-1" />
+                  {t("vault.hosts.moveSelected", { count: selectedHostIds.size })}
+                </Button>
                 <Button
                   variant="destructive"
                   size="sm"
@@ -1527,6 +1560,26 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
                 {...vaultHostPanelResizeProps}
               />
             )}
+
+          {/* Local Shell Host Details Panel - for editing/saving local shell (CMD) hosts */}
+          {currentSection === "hosts" &&
+            isLocalShellHostPanelOpen && (
+              <LocalShellHostDetailsPanel
+                key={editingLocalShellHost?.id ?? "local-shell-new"}
+                initialData={editingLocalShellHost}
+                groups={allGroupPaths}
+                defaultGroup={
+                  editingLocalShellHost
+                    ? undefined
+                    : newHostGroupPath || selectedGroupPath
+                }
+                onSave={(host) => handleSaveLocalShellHost(host)}
+                onSaveAndConnect={(host) => handleSaveLocalShellHost(host, true)}
+                onCancel={handleCancelLocalShellHost}
+                layout="inline"
+                {...vaultHostPanelResizeProps}
+              />
+            )}
         </div>
       </div>
 
@@ -1758,6 +1811,43 @@ export function VaultViewLayout({ ctx }: { ctx: VaultViewLayoutContext }) {
         </DialogContent>
       </Dialog>
 
+      <Dialog open={isMoveHostsOpen} onOpenChange={setIsMoveHostsOpen}>
+        <DialogContent>
+          <DialogHeader>
+            <DialogTitle>{t("vault.hosts.moveSelected", { count: selectedHostIds.size })}</DialogTitle>
+            <DialogDescription>{t("vault.hosts.moveSelected.description")}</DialogDescription>
+          </DialogHeader>
+          <Combobox
+            options={[
+              { value: "", label: t("vault.hosts.allHosts") },
+              ...allGroupPaths
+                .filter((path: string) => path !== "General"
+                  || customGroups.includes("General")
+                  || allGroupPaths.some((group: string) => group.startsWith("General/")))
+                .map((path: string) => ({ value: path, label: path })),
+            ]}
+            value={moveTargetGroup}
+            onValueChange={setMoveTargetGroup}
+            ariaLabel={t("hostDetails.group.placeholder")}
+            placeholder={t("vault.hosts.allHosts")}
+            clearable={false}
+          />
+          <DialogFooter>
+            <Button variant="ghost" onClick={() => setIsMoveHostsOpen(false)}>{t("common.cancel")}</Button>
+            <Button
+              disabled={selectedHostIds.size === 0}
+              onClick={() => {
+                moveHostsToGroup(selectedHostIds, moveTargetGroup || null);
+                setIsMoveHostsOpen(false);
+                clearHostSelection();
+              }}
+            >
+              {t("vault.hosts.moveSelected", { count: selectedHostIds.size })}
+            </Button>
+          </DialogFooter>
+        </DialogContent>
+      </Dialog>
+
       <ImportVaultDialog
         open={isImportOpen}
         onOpenChange={setIsImportOpen}

components/vault/useVaultGroupDragHandlers.test.tsx

@@ -0,0 +1,85 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import React from 'react';
+import { act, create, type ReactTestRenderer } from 'react-test-renderer';
+import type { Host, ManagedSource } from '../../types';
+import { useVaultGroupDragHandlers } from './useVaultGroupDragHandlers';
+
+const host = (id: string, extra: Partial<Host> = {}): Host => ({
+  id, label: `Host ${id}`, hostname: `${id}.example`, username: 'user', port: 22,
+  tags: ['keep'], group: 'Old', ...extra,
+});
+
+test('bulk group move publishes all selected hosts together and preserves unselected hosts', async () => {
+  const original = [host('a'), host('b', { protocol: 'telnet' }), host('c')];
+  const writes: Host[][] = [];
+  await withActions(original, [], actions => {
+    act(() => actions.moveHostsToGroup(new Set(['a', 'b']), 'New/Nested'));
+    assert.equal(writes.length, 1);
+    assert.deepEqual(writes[0].map(h => h.group), ['New/Nested', 'New/Nested', 'Old']);
+    assert.equal(writes[0][2], original[2]);
+    assert.deepEqual(writes[0][0].tags, ['keep']);
+    assert.equal(writes[0][0].hostname, original[0].hostname);
+  }, writes);
+});
+
+test('mixed protocols entering and leaving managed groups retain single-host move rules', async () => {
+  const original = [host('ssh'), host('telnet', { protocol: 'telnet' }), host('local', { protocol: 'local' })];
+  const sources = [{ id: 'parent', groupName: 'Managed' }, { id: 'child', groupName: 'Managed/Nested' }] as ManagedSource[];
+  const writes: Host[][] = [];
+  await withActions(original, sources, actions => {
+    act(() => actions.moveHostsToGroup(new Set(original.map(h => h.id)), 'Managed/Nested'));
+    assert.equal(writes.length, 1);
+    assert.equal(writes[0][0].managedSourceId, 'child');
+    assert.equal(writes[0][0].label, 'Hostssh');
+    assert.equal(writes[0][1].managedSourceId, undefined);
+    assert.equal(writes[0][1].label, 'Host telnet');
+    assert.equal(writes[0][2].managedSourceId, undefined);
+    assert.equal(writes[0][2].label, 'Host local');
+  }, writes);
+  await withActions(writes[0], sources, actions => {
+    act(() => actions.moveHostsToGroup(new Set(original.map(h => h.id)), null));
+    assert.deepEqual(writes[1].map(h => h.group), ['', '', '']);
+    assert.ok(writes[1].every(h => h.managedSourceId === undefined));
+  }, writes);
+});
+
+test('same-group, missing and empty selections do not publish changes', async () => {
+  const writes: Host[][] = [];
+  await withActions([host('a')], [], actions => {
+    act(() => actions.moveHostsToGroup(new Set(['a']), 'Old'));
+    act(() => actions.moveHostsToGroup(new Set(['missing']), 'New'));
+    act(() => actions.moveHostsToGroup(new Set(), 'New'));
+    assert.equal(writes.length, 0);
+    act(() => actions.moveHostToGroup('a', 'New'));
+    assert.equal(writes.length, 1);
+    assert.equal(writes[0][0].group, 'New');
+  }, writes);
+});
+
+async function withActions(
+  hosts: Host[], managedSources: ManagedSource[],
+  run: (actions: ReturnType<typeof useVaultGroupDragHandlers>) => void,
+  writes: Host[][],
+) {
+  const previousWindow = globalThis.window;
+  const actEnvironment = globalThis as typeof globalThis & { IS_REACT_ACT_ENVIRONMENT?: boolean };
+  const previousAct = actEnvironment.IS_REACT_ACT_ENVIRONMENT;
+  actEnvironment.IS_REACT_ACT_ENVIRONMENT = true;
+  globalThis.window = { setTimeout: () => 1, clearTimeout: () => {} } as unknown as Window & typeof globalThis;
+  let renderer: ReactTestRenderer | undefined;
+  let actions: ReturnType<typeof useVaultGroupDragHandlers>;
+  function Probe() {
+    actions = useVaultGroupDragHandlers({ hosts, managedSources,
+      onUpdateHosts: next => writes.push(next), onUpdateManagedSources: () => {}, t: key => key });
+    return null;
+  }
+  try {
+    await act(async () => { renderer = create(<Probe />); });
+    run(actions!);
+  } finally {
+    await act(async () => renderer?.unmount());
+    globalThis.window = previousWindow;
+    actEnvironment.IS_REACT_ACT_ENVIRONMENT = previousAct;
+  }
+}

components/vault/useVaultGroupDragHandlers.ts

@@ -66,53 +66,40 @@ export function useVaultGroupDragHandlers({
       setDragOverDropTarget(path ? { kind: "group", path } : null);
     }, []);
   
-  const moveHostToGroup = useCallback((hostId: string, groupPath: string | null) => {
+  const moveHostsToGroup = useCallback((hostIds: ReadonlySet<string>, groupPath: string | null) => {
       const targetGroup = groupPath || "";
-      const hostToMove = hosts.find((h) => h.id === hostId);
-      if (!hostToMove || (hostToMove.group || "") === targetGroup) {
-        setDragOverDropTarget(null);
-        return;
-      }
-  
-      // Find the most specific (deepest) managed source that matches the target group
       const targetManagedSource = managedSources
         .filter(s => targetGroup === s.groupName || targetGroup.startsWith(s.groupName + "/"))
         .sort((a, b) => b.groupName.length - a.groupName.length)[0];
-  
-      const movedHost = {
-        ...hostToMove,
-        group: targetGroup,
-      };
-      const updatedHost = (() => {
-          const h = movedHost;
-  
-          // Only SSH hosts can be managed (SSH config only supports SSH)
-          const canBeManaged = !h.protocol || h.protocol === "ssh";
-  
-          // Sanitize label if moving to a managed group (SSH config requires no spaces in Host alias)
-          let label = h.label;
-          if (targetManagedSource && canBeManaged && label) {
-            label = label.replace(/\s/g, '');
-          }
-  
-          return {
-            ...h,
-            label,
-            group: targetGroup,
-            managedSourceId: (targetManagedSource && canBeManaged) ? targetManagedSource.id : undefined,
-          };
-        })();
-      onUpdateHosts(hosts.map((host) => (host.id === hostId ? updatedHost : host)));
+      let movedCount = 0;
+      const updatedHosts = hosts.map(host => {
+        if (!hostIds.has(host.id) || (host.group || "") === targetGroup) return host;
+        movedCount += 1;
+        const canBeManaged = !host.protocol || host.protocol === "ssh";
+        return {
+          ...host,
+          group: targetGroup,
+          label: targetManagedSource && canBeManaged
+            ? host.label.replace(/\s/g, '') : host.label,
+          managedSourceId: targetManagedSource && canBeManaged ? targetManagedSource.id : undefined,
+        };
+      });
       setDragOverDropTarget(null);
+      if (movedCount === 0) return;
+      // Publish the entire selection once; repeated single-host updates would
+      // each start from the same render snapshot and overwrite earlier moves.
+      onUpdateHosts(updatedHosts);
       pulseDropTarget(groupPath ? { kind: "group", path: groupPath } : { kind: "root" });
-      toast.success(
-        t("vault.hosts.moveToGroup.success", {
-          host: hostToMove.label,
-          group: groupPath || t("vault.hosts.allHosts"),
-        }),
-      );
+      toast.success(t("vault.hosts.moveMultiple.success", {
+        count: movedCount,
+        group: groupPath || t("vault.hosts.allHosts"),
+      }));
     }, [hosts, managedSources, onUpdateHosts, pulseDropTarget, t]);
-  
+
+  const moveHostToGroup = useCallback((hostId: string, groupPath: string | null) => {
+      moveHostsToGroup(new Set([hostId]), groupPath);
+    }, [moveHostsToGroup]);
+
   const getDropTargetClasses = (target: DropTarget) =>
       cn(
         isSameDropTarget(dragOverDropTarget, target) &&
@@ -151,6 +138,7 @@ export function useVaultGroupDragHandlers({
     handleUnmanageGroup,
     managedGroupPaths,
     moveHostToGroup,
+    moveHostsToGroup,
     setDragOverDropTarget,
     setGroupDragOverDropTarget,
   };

domain/aiSessionFork.test.ts

@@ -0,0 +1,318 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import {
+  buildForkTitle,
+  canForkFromMessage,
+  getForkableMessageIds,
+  planSessionFork,
+  stripMessageContinuationState,
+} from './aiSessionFork.ts';
+
+import type { ForkMessage } from './aiSessionFork.ts';
+
+let nextId = 0;
+const msg = (overrides: Partial<ForkMessage>): ForkMessage => ({
+  id: `m${nextId++}`,
+  role: 'assistant',
+  content: '',
+  timestamp: 0,
+  ...overrides,
+} as ForkMessage);
+
+const session = (messages: ForkMessage[], contextCompaction?: { summary: string; compactedMessageCount: number }) => ({
+  title: 'Debug deploy',
+  messages,
+  contextCompaction,
+});
+
+test('planSessionFork keeps the original untouched and plans a copy through the boundary', () => {
+  const user = msg({ role: 'user', content: 'run tests' });
+  const assistant = msg({ content: 'done, all green' });
+  const source = session([user, assistant]);
+  const plan = planSessionFork(source, assistant.id);
+  assert.equal(plan.ok, true);
+  if (!plan.ok) return;
+  assert.equal(plan.boundaryIndex, 1);
+  assert.deepEqual(plan.messages, [user, assistant]);
+  assert.equal(plan.title, 'Debug deploy (fork)');
+});
+
+test('planSessionFork rejects non-assistant and missing boundaries', () => {
+  const source = session([
+    msg({ role: 'user', content: 'hi' }),
+  ]);
+  assert.deepEqual(planSessionFork(source, source.messages[0].id), { ok: false, reason: 'not-assistant' });
+  assert.deepEqual(planSessionFork(source, 'missing'), { ok: false, reason: 'message-not-found' });
+});
+
+test('planSessionFork rejects failed, cancelled, running, and streaming boundaries', () => {
+  for (const executionStatus of ['failed', 'cancelled', 'running', 'pending']) {
+    const source = session([msg({ content: 'x', executionStatus })]);
+    assert.deepEqual(planSessionFork(source, source.messages[0].id), {
+      ok: false,
+      reason: 'not-completed',
+    });
+  }
+  const streamingSource = session([msg({ statusText: 'Waiting for response…' })]);
+  assert.deepEqual(planSessionFork(streamingSource, streamingSource.messages[0].id), {
+    ok: false,
+    reason: 'not-completed',
+  });
+  const failedSource = session([msg({ errorInfo: { type: 'provider', message: 'boom', retryable: true } })]);
+  assert.deepEqual(planSessionFork(failedSource, failedSource.messages[0].id), {
+    ok: false,
+    reason: 'not-completed',
+  });
+  const pendingSource = session([msg({ pendingApproval: {} })]);
+  assert.deepEqual(planSessionFork(pendingSource, pendingSource.messages[0].id), {
+    ok: false,
+    reason: 'not-completed',
+  });
+});
+
+test('planSessionFork rejects boundaries with dangling tool calls', () => {
+  const source = session([
+    msg({ role: 'user', content: 'hi' }),
+    msg({ content: '', toolCalls: [{ id: 'call-1' }] }),
+    msg({ content: '', toolCalls: [{ id: 'call-2' }] }),
+    msg({
+      role: 'tool',
+      content: 'ok',
+      toolResults: [{ toolCallId: 'call-1', content: 'out' }],
+    }),
+    msg({ content: 'final answer' }),
+  ]);
+  // call-2 never got a result inside the retained prefix
+  assert.deepEqual(planSessionFork(source, source.messages[4].id), {
+    ok: false,
+    reason: 'dangling-tool-call',
+  });
+  // forking at the tool-issuing assistant turns is not possible anyway
+  assert.deepEqual(planSessionFork(source, source.messages[2].id), {
+    ok: false,
+    reason: 'dangling-tool-call',
+  });
+});
+
+test('planSessionFork forks at the first turn boundary after results resolve', () => {
+  const source = session([
+    msg({ role: 'user', content: 'hi' }),
+    msg({ role: 'assistant', content: '', toolCalls: [{ id: 'call-1' }] }),
+    msg({ role: 'tool', content: 'ok', toolResults: [{ toolCallId: 'call-1', content: 'out' }] }),
+    msg({ role: 'assistant', content: 'all done' }),
+  ]);
+  assert.deepEqual(planSessionFork(source, source.messages[1].id), {
+    ok: false,
+    reason: 'dangling-tool-call',
+  });
+  const plan = planSessionFork(source, source.messages[3].id);
+  assert.equal(plan.ok, true);
+});
+
+test('planSessionFork rejects boundaries with dangling tool results', () => {
+  const source = session([
+    msg({ role: 'assistant', content: 'x' }),
+    msg({ role: 'tool', content: 'ok', toolResults: [{ toolCallId: 'orphan', content: 'out' }] }),
+    msg({ role: 'assistant', content: 'answer' }),
+  ]);
+  assert.deepEqual(planSessionFork(source, source.messages[2].id), {
+    ok: false,
+    reason: 'dangling-tool-result',
+  });
+});
+
+test('planSessionFork lets the compaction summary ride along while it stays accurate', () => {
+  const source = session(
+    [msg({ role: 'user', content: 'hi' }), msg({ content: 'done' })],
+    { summary: 'earlier talk', compactedMessageCount: 1 },
+  );
+  const plan = planSessionFork(source, source.messages[1].id);
+  assert.equal(plan.ok, true);
+  if (plan.ok) {
+    assert.deepEqual(plan.contextCompaction, { summary: 'earlier talk', compactedMessageCount: 1 });
+  }
+});
+
+test('planSessionFork refuses when the compaction summary would cover discarded messages', () => {
+  const early = msg({ content: 'early turn' });
+  const source = session(
+    [early, msg({ content: 'later turn' })],
+    { summary: 'covers both turns', compactedMessageCount: 2 },
+  );
+  assert.deepEqual(planSessionFork(source, early.id), {
+    ok: false,
+    reason: 'compaction-covers-discarded',
+  });
+});
+
+test('planSessionFork preserves provider replay metadata but strips turn state', () => {
+  const continuation = { reasoningParts: [{ text: 'chain of thought' }] };
+  const user = msg({ role: 'user', content: 'hi', providerContinuation: continuation, statusText: 'streaming…' });
+  const assistant = msg({ content: 'answer', providerContinuation: continuation });
+  const source = session([user, assistant]);
+  const plan = planSessionFork(source, assistant.id);
+  assert.equal(plan.ok, true);
+  if (plan.ok) {
+    for (const message of plan.messages) {
+      assert.equal(message.providerContinuation, continuation);
+      assert.equal(message.statusText, undefined);
+    }
+  }
+  // untouched source keeps its original message objects and turn state
+  assert.equal(source.messages[0].providerContinuation, continuation);
+  assert.equal(source.messages[0].statusText, 'streaming…');
+});
+
+test('planSessionFork pairs repeated tool-call ids by occurrence', () => {
+  const source = session([
+    msg({ role: 'user', content: 'hi' }),
+    msg({ role: 'assistant', content: '', toolCalls: [{ id: 'call-1' }] }),
+    msg({ role: 'tool', content: 'first', toolResults: [{ toolCallId: 'call-1', content: 'out 1' }] }),
+    msg({ role: 'assistant', content: '', toolCalls: [{ id: 'call-1' }] }),
+    msg({ role: 'assistant', content: 'answer' }),
+  ]);
+  // The provider reused call-1; the second occurrence never got a result.
+  assert.deepEqual(planSessionFork(source, source.messages[4].id), {
+    ok: false,
+    reason: 'dangling-tool-call',
+  });
+  const resolved = session([
+    msg({ role: 'assistant', content: '', toolCalls: [{ id: 'call-1' }] }),
+    msg({ role: 'tool', content: 'first', toolResults: [{ toolCallId: 'call-1', content: 'out 1' }] }),
+    msg({ role: 'assistant', content: '', toolCalls: [{ id: 'call-1' }] }),
+    msg({ role: 'tool', content: 'second', toolResults: [{ toolCallId: 'call-1', content: 'out 2' }] }),
+    msg({ role: 'assistant', content: 'answer' }),
+  ]);
+  assert.equal(planSessionFork(resolved, resolved.messages[4].id).ok, true);
+  // One result cannot satisfy two pending calls with the same id.
+  const underResolved = session([
+    msg({ role: 'assistant', content: '', toolCalls: [{ id: 'call-1' }, { id: 'call-1' }] }),
+    msg({ role: 'tool', content: 'single', toolResults: [{ toolCallId: 'call-1', content: 'out' }] }),
+    msg({ role: 'assistant', content: 'answer' }),
+  ]);
+  assert.deepEqual(planSessionFork(underResolved, underResolved.messages[2].id), {
+    ok: false,
+    reason: 'dangling-tool-call',
+  });
+});
+
+test('stripMessageContinuationState preserves values and clears transient state', () => {
+  const plain = msg({ content: 'x' });
+  assert.deepEqual(stripMessageContinuationState(plain), plain);
+  const withStatusText = msg({ content: 'x', statusText: 'streaming…' });
+  assert.notEqual(stripMessageContinuationState(withStatusText), withStatusText);
+  const withPendingApproval = msg({ content: 'x', pendingApproval: {} });
+  assert.notEqual(stripMessageContinuationState(withPendingApproval), withPendingApproval);
+  const continuationOnly = msg({ content: 'x', providerContinuation: {} });
+  assert.deepEqual(stripMessageContinuationState(continuationOnly), continuationOnly);
+});
+
+test('buildForkTitle appends a fork marker without double-suffixing', () => {
+  assert.equal(buildForkTitle('Debug deploy'), 'Debug deploy (fork)');
+  assert.equal(buildForkTitle('Debug deploy (fork)'), 'Debug deploy (fork)');
+  assert.equal(buildForkTitle(''), 'New Chat (fork)');
+});
+
+test('canForkFromMessage mirrors planSessionFork success', () => {
+  const source = session([msg({ role: 'user', content: 'hi' }), msg({ content: 'done' })]);
+  assert.equal(canForkFromMessage(source, source.messages[1].id), true);
+  assert.equal(canForkFromMessage(source, source.messages[0].id), false);
+  assert.equal(canForkFromMessage(source, 'nope'), false);
+});
+
+test('fork keeps output previews but removes source-only saved-output references', () => {
+  const assistant = msg({ content: 'preview handleId=tool-output-abc', toolResults: [{ toolCallId: 'call', content: '{"handleId":"tool-output-xyz","preview":"retained"}' }] });
+  const source = session([msg({ toolCalls: [{ id: 'call' }] }), assistant], { summary: 'archive handleId=tool-output-summary', compactedMessageCount: 1 });
+  const plan = planSessionFork(source, assistant.id);
+  assert.ok(plan.ok);
+  assert.doesNotMatch(JSON.stringify(plan), /tool-output-/);
+  assert.match(plan.messages[1].content, /preview/);
+  assert.match(plan.messages[1].toolResults![0].content!, /retained/);
+  assert.equal(JSON.parse(plan.messages[1].toolResults![0].content!).handleId, null);
+  assert.match(source.messages[1].content, /tool-output-abc/);
+});
+
+test('fork removes source output handles only from tool_output_read arguments', () => {
+  const read = msg({ toolCalls: [{ id: 'read', name: 'tool_output_read', arguments: { handleId: 'tool-output-source', offset: 12 } }] });
+  const done = msg({ toolResults: [{ toolCallId: 'read', content: 'preview' }], content: 'done' });
+  const source = session([read, done]);
+  const plan = planSessionFork(source, done.id);
+  assert.ok(plan.ok);
+  assert.equal(plan.messages[0].toolCalls![0].arguments!.handleId, undefined);
+  assert.equal(plan.messages[0].toolCalls![0].arguments!.offset, 12);
+  assert.equal(read.toolCalls![0].arguments!.handleId, 'tool-output-source');
+
+  const other = msg({ toolCalls: [{ id: 'other', name: 'custom_tool', arguments: { handleId: 'tool-output-not-owned-here' } }] });
+  assert.deepEqual(stripMessageContinuationState(other).toolCalls, other.toolCalls);
+});
+
+test('fork refuses source output references in provider reasoning without changing signed metadata', () => {
+  const continuation = { reasoningParts: [{ text: 'Read handleId=tool-output-source for details', providerOptions: { anthropic: { signature: 'valid-signature' } } }] };
+  const source = session([msg({ content: 'done', providerContinuation: continuation })]);
+  assert.deepEqual(planSessionFork(source, source.messages[0].id), { ok: false, reason: 'source-output-reasoning' });
+  assert.equal(canForkFromMessage(source, source.messages[0].id), false);
+  assert.equal(source.messages[0].providerContinuation, continuation);
+  assert.equal(continuation.reasoningParts[0].text, 'Read handleId=tool-output-source for details');
+});
+
+test('fork eligibility does not clone or scan retained message bodies', () => {
+  const assistant = msg({ content: 'completed' });
+  Object.defineProperty(assistant, 'content', { get() { throw new Error('eligibility should not build a transcript'); } });
+  assert.equal(canForkFromMessage(session([assistant]), assistant.id), true);
+});
+
+test('one-pass fork eligibility matches clicked-boundary validation', () => {
+  const messages = [
+    msg({ role: 'user', content: 'start' }),
+    msg({ content: 'first completed reply' }),
+    msg({ toolCalls: [{ id: 'reused' }, { id: 'reused' }] }),
+    msg({ role: 'tool', toolResults: [{ toolCallId: 'reused', content: 'one' }] }),
+    msg({ content: 'still unresolved' }),
+    msg({ role: 'tool', toolResults: [{ toolCallId: 'reused', content: 'two' }] }),
+    msg({ content: 'complete exchange' }),
+    msg({ executionStatus: 'failed' }),
+    msg({ content: 'unsafe reasoning', providerContinuation: { reasoningParts: [{ text: 'Read tool-output-source' }] } }),
+    msg({ content: 'after unsafe reasoning' }),
+  ];
+  for (const compactedMessageCount of [0, 3, messages.length]) {
+    const source = session(messages, { summary: 'summary', compactedMessageCount });
+    assert.deepEqual([...getForkableMessageIds(source)], messages.filter(message => planSessionFork(source, message.id).ok).map(message => message.id));
+  }
+  const orphan = session([msg({ role: 'tool', toolResults: [{ toolCallId: 'orphan' }] }), msg({ content: 'reply' })]);
+  assert.equal(getForkableMessageIds(orphan).size, 0);
+});
+
+test('fork removes bare output identifiers in transcript previews while preserving JSON', () => {
+  const assistant = msg({ content: 'Read tool-output-source with tool_output_read', thinking: 'Output tool-output-source is saved', toolResults: [{ toolCallId: 'call', content: '{"handleId":"tool-output-source","preview":"Read tool-output-source"}' }] });
+  const plan = planSessionFork(session([msg({ toolCalls: [{ id: 'call' }] }), assistant]), assistant.id);
+  assert.ok(plan.ok);
+  assert.doesNotMatch(JSON.stringify(plan.messages), /tool-output-source/);
+  const parsed = JSON.parse(plan.messages[1].toolResults![0].content!);
+  assert.equal(parsed.handleId, null);
+  assert.match(parsed.preview, /Read/);
+  assert.match(assistant.content, /tool-output-source/);
+});
+
+test('fork sanitizes attachment previews without changing attachment data or identity', () => {
+  const attachment = { base64Data: 'SEVMTE8=', mediaType: 'text/plain', filename: 'terminal-selection.log', terminalSelection: true, lineCount: 3, filePath: '/original/selection.log', previewText: 'Read tool-output-selection with tool_output_read' };
+  const image = { base64Data: 'UE5H', mediaType: 'image/png', filename: 'original.png' };
+  const user = msg({ role: 'user', content: 'Inspect', attachments: [attachment, image], images: [attachment] });
+  const assistant = msg({ content: 'done' });
+  const plan = planSessionFork(session([user, assistant]), assistant.id);
+  assert.ok(plan.ok);
+  assert.doesNotMatch(plan.messages[0].attachments![0].previewText!, /tool-output-selection/);
+  assert.deepEqual({ ...plan.messages[0].attachments![0], previewText: attachment.previewText }, attachment);
+  assert.equal(plan.messages[0].attachments![1], image);
+  assert.doesNotMatch(plan.messages[0].images![0].previewText!, /tool-output-selection/);
+  assert.equal(user.attachments![0], attachment);
+  assert.equal(attachment.previewText, 'Read tool-output-selection with tool_output_read');
+});
+
+test('fork still rejects an unresolved retained call even when compaction covers it', () => {
+  const unresolved = msg({ toolCalls: [{ id: 'pending' }], executionStatus: 'cancelled' });
+  const done = msg({ content: 'later completed answer' });
+  const source = session([unresolved, done], { summary: 'the earlier call was interrupted', compactedMessageCount: 1 });
+  assert.deepEqual(planSessionFork(source, done.id), { ok: false, reason: 'dangling-tool-call' });
+  assert.equal(getForkableMessageIds(source).has(done.id), false);
+});

domain/aiSessionFork.ts

@@ -0,0 +1,276 @@
+import type { ChatMessageAttachment } from '../infrastructure/ai/types';
+import type { ProviderContinuation } from '../infrastructure/ai/providerContinuation';
+
+/**
+ * Pure planning logic for "Fork from here": copy an AI chat session up to a
+ * completed assistant response into a new session, leaving the original
+ * conversation untouched in history.
+ *
+ * Refusals (per the feature contract):
+ * - only completed assistant-response turn boundaries fork — streaming, failed,
+ *   cancelled, or in-progress turns are rejected,
+ * - every tool call in the retained prefix must have a paired result and
+ *   vice versa (no dangling calls or results on the branch),
+ * - a stored compaction summary that would cover messages discarded by the
+ *   branch is refused (the summary must stay accurate for the fork),
+ * - incomplete-turn state (status text, pending approvals) is stripped while
+ *   the per-message provider replay metadata is preserved, so the fresh
+ *   provider thread replays the retained history.
+ */
+
+export type ForkRefusalReason =
+  | 'message-not-found'
+  | 'not-assistant'
+  | 'not-completed'
+  | 'dangling-tool-call'
+  | 'dangling-tool-result'
+  | 'compaction-covers-discarded'
+  | 'source-output-reasoning';
+
+/** A message type that carries the fork-relevant subset (e.g. ChatMessage). */
+export type ForkMessageLike = {
+  id: string;
+  role: 'user' | 'assistant' | 'system' | 'tool';
+  content: string;
+  thinking?: string;
+  providerContinuation?: ProviderContinuation;
+  attachments?: ReadonlyArray<ChatMessageAttachment>;
+  images?: ReadonlyArray<ChatMessageAttachment>;
+  toolCalls?: ReadonlyArray<{ id: string; name?: string; arguments?: Record<string, unknown> }>;
+  toolResults?: ReadonlyArray<{ toolCallId: string; content?: string; isError?: boolean }>;
+  errorInfo?: unknown;
+  statusText?: string;
+  pendingApproval?: unknown;
+  executionStatus?: string;
+};
+
+/** Structural subset of ChatMessage the fork planner needs. */
+export type ForkMessage = ForkMessageLike & { timestamp?: number };
+
+export type ForkPlan<M extends ForkMessageLike = ForkMessage> =
+  | {
+    ok: true;
+    boundaryIndex: number;
+    title: string;
+    messages: M[];
+    contextCompaction?: ForkContextCompaction;
+  }
+  | { ok: false; reason: ForkRefusalReason };
+
+export type ForkContextCompaction = {
+  summary: string;
+  compactedMessageCount: number;
+};
+
+const INCOMPLETE_EXECUTION_STATUSES = new Set([
+  'pending',
+  'running',
+  'failed',
+  'cancelled',
+]);
+
+function isCompletedResponse(message: ForkMessageLike): boolean {
+  return message.role === 'assistant'
+    && message.errorInfo == null
+    && message.statusText == null
+    && message.pendingApproval == null
+    && !INCOMPLETE_EXECUTION_STATUSES.has(message.executionStatus ?? '');
+}
+
+function hasSourceOutputReasoning(message: ForkMessageLike): boolean {
+  return (message.providerContinuation?.reasoningParts ?? []).some(
+    part => /\btool-output-[A-Za-z0-9-]+/.test(part.text),
+  );
+}
+
+/** Eligibility only: never copy/sanitize transcript content while rendering. */
+export function getForkableMessageIds(source: {
+  messages: readonly ForkMessageLike[];
+  contextCompaction?: ForkContextCompaction;
+}): Set<string> {
+  const ids = new Set<string>();
+  const pending = new Map<string, number>();
+  let pendingCount = 0;
+  let orphanResult = false;
+  let sourceOutputReasoning = false;
+  for (const [index, message] of source.messages.entries()) {
+    sourceOutputReasoning ||= hasSourceOutputReasoning(message);
+    for (const call of message.toolCalls ?? []) {
+      if (!call.id) continue;
+      pending.set(call.id, (pending.get(call.id) ?? 0) + 1);
+      pendingCount += 1;
+    }
+    for (const result of message.toolResults ?? []) {
+      if (!result.toolCallId) continue;
+      const count = pending.get(result.toolCallId) ?? 0;
+      if (count === 0) orphanResult = true;
+      else {
+        pending.set(result.toolCallId, count - 1);
+        pendingCount -= 1;
+      }
+    }
+    if (isCompletedResponse(message) && pendingCount === 0
+      && !orphanResult && !sourceOutputReasoning
+      && (source.contextCompaction?.compactedMessageCount ?? 0) <= index + 1) {
+      ids.add(message.id);
+    }
+  }
+  return ids;
+}
+
+/**
+ * Validate that every tool call in the retained prefix is paired with a
+ * result and vice versa. Providers may reuse a tool-call id across turns, so
+ * each result is consumed by the nearest preceding unresolved call with the
+ * same id (same pairing rule as buildHistoricalToolReplayMaps): a result with
+ * no pending call before it is dangling, and so is a call still pending after
+ * the walk.
+ */
+function validateToolCallResultPairing(
+  messages: readonly ForkMessageLike[],
+): 'dangling-tool-call' | 'dangling-tool-result' | null {
+  const pendingCallCounts = new Map<string, number>();
+  for (const message of messages) {
+    for (const toolCall of message.toolCalls ?? []) {
+      if (!toolCall?.id) continue;
+      pendingCallCounts.set(toolCall.id, (pendingCallCounts.get(toolCall.id) ?? 0) + 1);
+    }
+    for (const toolResult of message.toolResults ?? []) {
+      const id = toolResult?.toolCallId;
+      if (!id) continue;
+      const pendingCount = pendingCallCounts.get(id) ?? 0;
+      if (pendingCount === 0) return 'dangling-tool-result';
+      pendingCallCounts.set(id, pendingCount - 1);
+    }
+  }
+  for (const pendingCount of pendingCallCounts.values()) {
+    if (pendingCount > 0) return 'dangling-tool-call';
+  }
+  return null;
+}
+
+/**
+ * Strip incomplete-turn state so the branch starts clean; per-message provider
+ * continuation metadata (Responses reasoning items, OpenAI Chat assistant
+ * fields, tool-call wire options) is preserved because the fork's fresh
+ * provider thread replays the retained history through it and safely discards
+ * exchanges whose metadata no longer matches the active provider.
+ */
+/** Keep the preview but remove unusable source-session output references. */
+function stripSourceOutputHandles(value: string): string {
+  return value
+    .replace(/\bhandleId=tool-output-[A-Za-z0-9-]+/g, '[saved output remains in the original chat]')
+    .replace(/"handleId"\s*:\s*"tool-output-[A-Za-z0-9-]+"/g, '"handleId":null,"note":"Saved output remains in the original chat"')
+    .replace(/\btool-output-[A-Za-z0-9-]+/g, '[saved output remains in the original chat]');
+}
+
+function stripAttachmentPreview<A extends { previewText?: string }>(attachment: A): A {
+  return attachment.previewText
+    ? { ...attachment, previewText: stripSourceOutputHandles(attachment.previewText) }
+    : attachment;
+}
+
+export function stripMessageContinuationState<M extends ForkMessageLike>(message: M): M {
+  const next = {
+    ...message,
+    content: stripSourceOutputHandles(message.content),
+    ...(message.attachments ? { attachments: message.attachments.map(stripAttachmentPreview) } : {}),
+    ...(message.images ? { images: message.images.map(stripAttachmentPreview) } : {}),
+    ...(message.thinking ? { thinking: stripSourceOutputHandles(message.thinking) } : {}),
+    ...(message.toolCalls ? {
+      toolCalls: message.toolCalls.map(call => {
+        if (call.name !== 'tool_output_read'
+          || typeof call.arguments?.handleId !== 'string'
+          || !call.arguments.handleId.startsWith('tool-output-')) return call;
+        const args = { ...call.arguments };
+        delete args.handleId;
+        return { ...call, arguments: args };
+      }),
+    } : {}),
+    ...(message.toolResults ? {
+      toolResults: message.toolResults.map(result => ({
+        ...result,
+        ...(result.content ? { content: stripSourceOutputHandles(result.content) } : {}),
+      })),
+    } : {}),
+  };
+  delete next.statusText;
+  delete next.pendingApproval;
+  return next;
+}
+
+export function buildForkTitle(title: string): string {
+  const base = (title ?? '').trim() || 'New Chat';
+  return base.endsWith('(fork)') ? base : `${base} (fork)`;
+}
+
+/** Structural subset of AISession the fork planner needs. */
+export type ForkSourceSession<M extends ForkMessageLike = ForkMessage> = {
+  title: string;
+  messages: readonly M[];
+  contextCompaction?: ForkContextCompaction;
+};
+
+/**
+ * Plan a fork at `messageId`. Returns a refusal reason when the boundary is
+ * not a safe completed turn, or the retained message list (trimmed of
+ * incomplete-turn state, keeping provider replay metadata) plus the
+ * carried-over compaction (when still accurate).
+ */
+export function planSessionFork<M extends ForkMessageLike>(
+  source: ForkSourceSession<M>,
+  messageId: string,
+): ForkPlan<M> {
+  const boundaryIndex = source.messages.findIndex(
+    (message) => message.id === messageId,
+  );
+  if (boundaryIndex === -1) return { ok: false, reason: 'message-not-found' };
+  const boundary = source.messages[boundaryIndex];
+  if (boundary.role !== 'assistant') return { ok: false, reason: 'not-assistant' };
+  if (!isCompletedResponse(boundary)) return { ok: false, reason: 'not-completed' };
+
+  const retained = source.messages.slice(0, boundaryIndex + 1);
+
+  // Provider reasoning can be signed: replacing text or dropping only that
+  // block can invalidate its tool exchange. Refuse this cut without changing
+  // the source metadata rather than leaking an unusable source-only handle.
+  if (retained.some(hasSourceOutputReasoning)) {
+    return { ok: false, reason: 'source-output-reasoning' };
+  }
+
+  const pairingRefusal = validateToolCallResultPairing(retained);
+  if (pairingRefusal) return { ok: false, reason: pairingRefusal };
+
+  // A stored compaction summary covers the earliest `compactedMessageCount`
+  // persisted messages. The summary must never cover messages discarded by
+  // the branch, so refuse when its coverage would exceed the retained prefix.
+  const compaction = source.contextCompaction;
+  let nextCompaction: ForkContextCompaction | undefined;
+  if (compaction) {
+    if (compaction.compactedMessageCount > retained.length) {
+      return { ok: false, reason: 'compaction-covers-discarded' };
+    }
+    nextCompaction = {
+      summary: stripSourceOutputHandles(compaction.summary),
+      compactedMessageCount: compaction.compactedMessageCount,
+    };
+  }
+
+  return {
+    ok: true,
+    boundaryIndex,
+    title: buildForkTitle(source.title),
+    messages: retained.map(stripMessageContinuationState),
+    ...(nextCompaction ? { contextCompaction: nextCompaction } : {}),
+  } as ForkPlan<M>;
+}
+
+export function canForkFromMessage(
+  source: {
+    messages: readonly ForkMessageLike[];
+    contextCompaction?: ForkContextCompaction;
+  },
+  messageId: string,
+): boolean {
+  return getForkableMessageIds(source).has(messageId);
+}

domain/aiUndoLastTurn.test.ts

@@ -0,0 +1,245 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import type { AISession, ChatMessage } from '../infrastructure/ai/types.ts';
+import {
+  buildUndoLastTurnBranch,
+  hasUnresolvedToolCalls,
+  resolveUndoLastTurnBoundary,
+} from './aiUndoLastTurn.ts';
+
+const user = (content: string): ChatMessage => ({
+  id: `u_${content}`,
+  role: 'user',
+  content,
+  timestamp: 1,
+});
+const assistant = (content: string, extra: Partial<ChatMessage> = {}): ChatMessage => ({
+  id: `a_${content}`,
+  role: 'assistant',
+  content,
+  timestamp: 2,
+  ...extra,
+});
+const session = (messages: ChatMessage[], extra: Partial<AISession> = {}): AISession => ({
+  id: 'chat-1',
+  title: 'Chat',
+  agentId: 'catty',
+  scope: { type: 'terminal', targetId: 't1' },
+  messages,
+  createdAt: 1,
+  updatedAt: 2,
+  ...extra,
+});
+
+test('resolveUndoLastTurnBoundary finds the last user message index', () => {
+  const messages = [user('one'), assistant('reply'), user('two'), assistant('reply2')];
+  assert.equal(resolveUndoLastTurnBoundary(messages), 2);
+});
+
+test('resolveUndoLastTurnBoundary returns null without a user message', () => {
+  assert.equal(resolveUndoLastTurnBoundary([assistant('hello')]), null);
+  assert.equal(resolveUndoLastTurnBoundary([]), null);
+});
+
+test('resolveUndoLastTurnBoundary refuses boundaries inside the compacted prefix', () => {
+  const messages = [user('compacted'), assistant('x'), user('last'), assistant('y')];
+  assert.equal(resolveUndoLastTurnBoundary(messages, 3), null);
+  assert.equal(resolveUndoLastTurnBoundary(messages, 2), 2);
+});
+
+test('resolveUndoLastTurnBoundary refuses cuts between a tool call and its result', () => {
+  // The call sits in the kept prefix while its result would be cut away.
+  const split = [
+    assistant('', {
+      toolCalls: [{ id: 'call-1', name: 'harness.terminal.exec', arguments: {} }],
+    }),
+    user('again?'),
+    assistant('', {
+      toolResults: [{ toolCallId: 'call-1', content: 'ok' }],
+    }),
+  ];
+  assert.equal(resolveUndoLastTurnBoundary(split), null);
+  assert.ok(hasUnresolvedToolCalls(split.slice(0, 2)));
+  // Result already inside the kept prefix — the boundary is safe.
+  const resolved = [
+    assistant('', {
+      toolCalls: [{ id: 'call-1', name: 'harness.terminal.exec', arguments: {} }],
+      toolResults: [{ toolCallId: 'call-1', content: 'ok' }],
+    }),
+    user('again?'),
+    assistant('done'),
+  ];
+  assert.equal(hasUnresolvedToolCalls(resolved.slice(0, 1)), false);
+  assert.equal(resolveUndoLastTurnBoundary(resolved), 1);
+});
+
+test('buildUndoLastTurnBranch branches before the last user turn and restores it', () => {
+  const source = session([
+    user('first'),
+    assistant('answer'),
+    user('bad prompt'),
+    assistant('bad answer'),
+  ]);
+  const result = buildUndoLastTurnBranch(source, { newId: 'chat-2', now: 42 });
+  assert.ok(result);
+  assert.equal(result.session.id, 'chat-2');
+  assert.deepEqual(result.session.messages.map((m) => m.content), ['first', 'answer']);
+  assert.equal(result.restored.text, 'bad prompt');
+  // Original session untouched (non-destructive).
+  assert.equal(source.messages.length, 4);
+});
+
+test('buildUndoLastTurnBranch clears the external agent session id and keeps compaction', () => {
+  const source = session(
+    [user('compacted'), assistant('x'), user('last'), assistant('y')],
+    {
+      externalSessionId: 'prov-1',
+      contextCompaction: { summary: 'summary', compactedMessageCount: 2 },
+    },
+  );
+  const result = buildUndoLastTurnBranch(source, { newId: 'chat-2', now: 7 });
+  assert.ok(result);
+  assert.equal(result.session.externalSessionId, undefined);
+  assert.deepEqual(result.session.contextCompaction, { summary: 'summary', compactedMessageCount: 2 });
+});
+
+test('buildUndoLastTurnBranch restores message attachments into composer uploads', () => {
+  const source = session([
+    user('with file'),
+    assistant('ok'),
+    {
+      id: 'u_last',
+      role: 'user',
+      content: 'look at this',
+      timestamp: 3,
+      attachments: [
+        { base64Data: 'QUJD', mediaType: 'text/plain', filename: 'notes.txt', lineCount: 3 },
+      ],
+    },
+  ]);
+  const result = buildUndoLastTurnBranch(source, { newId: 'chat-2', now: 99 });
+  assert.ok(result);
+  assert.deepEqual(result.restored.attachments, [
+    {
+      id: 'undo_99_0',
+      filename: 'notes.txt',
+      mediaType: 'text/plain',
+      base64Data: 'QUJD',
+      dataUrl: 'data:text/plain;base64,QUJD',
+      lineCount: 3,
+    },
+  ]);
+});
+
+test('buildUndoLastTurnBranch restores the undone turn selected user skills', () => {
+  const source = session([
+    user('first'),
+    assistant('answer'),
+    { ...user('undo me'), selectedUserSkillSlugs: ['web-search', 'notes-writer'] },
+    assistant('bad answer'),
+  ]);
+  const result = buildUndoLastTurnBranch(source, { newId: 'chat-2', now: 42 });
+  assert.ok(result);
+  assert.deepEqual(result.restored.selectedUserSkillSlugs, ['web-search', 'notes-writer']);
+  // Original session untouched (non-destructive).
+  assert.deepEqual(source.messages[2]?.selectedUserSkillSlugs, ['web-search', 'notes-writer']);
+});
+
+test('buildUndoLastTurnBranch restores no skill slugs for a plain turn', () => {
+  const source = session([user('first'), assistant('answer'), user('undo me'), assistant('ok')]);
+  const result = buildUndoLastTurnBranch(source, { newId: 'chat-2', now: 42 });
+  assert.ok(result);
+  assert.deepEqual(result.restored.selectedUserSkillSlugs, []);
+});
+
+test('buildUndoLastTurnBranch returns null when no undo boundary exists', () => {
+  assert.equal(
+    buildUndoLastTurnBranch(session([assistant('only answer')]), { newId: 'x', now: 1 }),
+    null,
+  );
+});
+
+test('buildUndoLastTurnBranch resets the title when undo removes the first turn', () => {
+  // Undoing the first turn leaves the branch with no user message at all, so
+  // the inherited title was derived from the removed prompt and would stay
+  // stale forever (auto-titling only runs for untitled/New Chat sessions).
+  const source = session([user('first prompt'), assistant('reply')], { title: 'first prompt' });
+  const result = buildUndoLastTurnBranch(source, { newId: 'chat-branch', now: 100 });
+  assert.ok(result);
+  assert.equal(result?.session.messages.length, 0);
+  assert.equal(result?.restored.text, 'first prompt');
+  assert.equal(result?.session.title, 'New Chat');
+});
+
+test('buildUndoLastTurnBranch keeps the title when the retained user turn is note-only', () => {
+  // A note-only send persists empty user text while the mentioned note rides
+  // on the attachment (its title seeded the conversation title), so a
+  // blank-content retained user turn must still count as "a user message is
+  // kept" and must not reset the title to the untitled placeholder.
+  const noteOnlyUser: ChatMessage = {
+    id: 'u_note-only',
+    role: 'user',
+    content: '',
+    timestamp: 3,
+    attachments: [{
+      base64Data: '',
+      mediaType: 'text/markdown',
+      filename: 'plan.md',
+      vaultNoteId: 'note-1',
+      vaultNoteTitle: 'Deploy plan',
+      previewText: '# Deploy plan',
+    }],
+  };
+  const source = session(
+    [noteOnlyUser, assistant('reply'), user('second prompt'), assistant('reply2')],
+    { title: 'Deploy plan' },
+  );
+  const result = buildUndoLastTurnBranch(source, { newId: 'chat-branch', now: 100 });
+  assert.ok(result);
+  assert.equal(result?.session.title, 'Deploy plan');
+});
+
+test('buildUndoLastTurnBranch keeps the title when a user message is retained', () => {
+  const source = session(
+    [user('first prompt'), assistant('reply'), user('second prompt'), assistant('reply2')],
+    { title: 'renamed by user' },
+  );
+  const result = buildUndoLastTurnBranch(source, { newId: 'chat-branch', now: 100 });
+  assert.ok(result);
+  assert.equal(result?.session.messages.length, 2);
+  assert.equal(result?.restored.text, 'second prompt');
+  // The retained prefix still contains a user message, so the source title
+  // keeps describing the branch's conversation.
+  assert.equal(result?.session.title, 'renamed by user');
+});
+
+test('undo allows a failed last reply while retaining portable replay metadata', () => {
+  const continuation = { reasoningParts: [{ text: 'checked', providerOptions: { anthropic: { signature: 'signed-thinking' } } }] };
+  const source = session([
+    user('first'),
+    assistant('first answer', { providerContinuation: continuation }),
+    user('retry this request'),
+    assistant('request failed', { executionStatus: 'failed' }),
+  ], { externalSessionId: 'original-provider-thread' });
+  const result = buildUndoLastTurnBranch(source, { newId: 'branch', now: 99 });
+  assert.ok(result);
+  assert.deepEqual(result.session.messages[1].providerContinuation, continuation);
+  assert.equal(result.session.externalSessionId, undefined);
+  assert.equal(result.restored.text, 'retry this request');
+  assert.equal(source.messages.length, 4);
+});
+
+test('safe boundary does not pair a reused call ID with an earlier result', () => {
+  const prefix = [
+    assistant('first call', { toolCalls: [{ id: 'reused', name: 'terminal_execute', arguments: {} }] }),
+    assistant('first result', { toolResults: [{ toolCallId: 'reused', content: 'done' }] }),
+    assistant('second call', { toolCalls: [{ id: 'reused', name: 'terminal_execute', arguments: {} }] }),
+  ];
+  assert.equal(resolveUndoLastTurnBoundary([...prefix, user('latest')]), null);
+  assert.equal(resolveUndoLastTurnBoundary([
+    ...prefix,
+    assistant('second result', { toolResults: [{ toolCallId: 'reused', content: 'done again' }] }),
+    user('latest'),
+  ]), 4);
+});

domain/aiUndoLastTurn.ts

@@ -0,0 +1,154 @@
+import type {
+  AISession,
+  ChatMessage,
+  ChatMessageAttachment,
+  UploadedFile,
+} from '../infrastructure/ai/types';
+
+/**
+ * Non-destructive "undo last turn" for AI chat sessions.
+ *
+ * Undo branches the conversation at the boundary *before* the latest user
+ * message instead of truncating the original session. The original session
+ * stays in history untouched; the branch (without the last turn) becomes the
+ * conversation the user continues, and the undone user message is restored
+ * into the composer for editing and resending.
+ */
+
+export interface UndoLastTurnRestoredDraft {
+  text: string;
+  attachments: UploadedFile[];
+  selectedUserSkillSlugs: string[];
+}
+
+export interface UndoLastTurnResult {
+  /** Branched copy of the source session without the last user turn. */
+  session: AISession;
+  /** Undone user message content for the composer. */
+  restored: UndoLastTurnRestoredDraft;
+}
+
+/**
+ * True when any assistant tool call in `messages` has no matching tool result
+ * inside the same list. Cutting between a tool call and its result would
+ * desync agent tool bookkeeping, so such boundaries are rejected.
+ */
+export function hasUnresolvedToolCalls(messages: readonly ChatMessage[]): boolean {
+  // Providers may reuse tool-call IDs across a session. Pair each result with
+  // the nearest preceding unresolved call carrying the same ID (same strategy
+  // as `repairToolMessageIntegrity`), otherwise a result for an earlier
+  // occurrence would satisfy a later call that reused the ID.
+  const pendingCalls = new Map<string, number>();
+  for (const message of messages) {
+    for (const call of message.toolCalls ?? []) {
+      pendingCalls.set(call.id, (pendingCalls.get(call.id) ?? 0) + 1);
+    }
+    for (const result of message.toolResults ?? []) {
+      const pending = pendingCalls.get(result.toolCallId) ?? 0;
+      if (pending > 0) pendingCalls.set(result.toolCallId, pending - 1);
+    }
+  }
+  for (const pending of pendingCalls.values()) {
+    if (pending > 0) return true;
+  }
+  return false;
+}
+
+/**
+ * Index of the cut point for undoing the last turn (the last user message).
+ * Returns null when undo is not offered:
+ * - there is no user message at all,
+ * - the boundary would fall inside the compacted prefix (its summary would no
+ *   longer match the kept messages),
+ * - cutting there would split an assistant tool call from its result.
+ */
+export function resolveUndoLastTurnBoundary(
+  messages: readonly ChatMessage[],
+  compactedMessageCount = 0,
+): number | null {
+  let lastUserIndex = -1;
+  for (let i = messages.length - 1; i >= 0; i -= 1) {
+    if (messages[i].role === 'user') {
+      lastUserIndex = i;
+      break;
+    }
+  }
+  if (lastUserIndex < 0) return null;
+  if (lastUserIndex < compactedMessageCount) return null;
+  const keptPrefix = messages.slice(0, lastUserIndex);
+  if (hasUnresolvedToolCalls(keptPrefix)) return null;
+  return lastUserIndex;
+}
+
+/** Map a persisted message attachment back to a composer upload (by value). */
+export function buildRestoredAttachments(
+  message: ChatMessage,
+  now: number,
+): UploadedFile[] {
+  const attachments: ChatMessageAttachment[] = message.attachments ?? message.images ?? [];
+  return attachments.map((attachment, index) => ({
+    id: `undo_${now}_${index}`,
+    filename: attachment.filename ?? '',
+    mediaType: attachment.mediaType,
+    base64Data: attachment.base64Data,
+    dataUrl: attachment.base64Data
+      ? `data:${attachment.mediaType};base64,${attachment.base64Data}`
+      : '',
+    ...(attachment.filePath !== undefined ? { filePath: attachment.filePath } : {}),
+    ...(attachment.terminalSelection ? { terminalSelection: true } : {}),
+    ...(attachment.vaultNoteId !== undefined ? { vaultNoteId: attachment.vaultNoteId } : {}),
+    ...(attachment.vaultNoteTitle !== undefined ? { vaultNoteTitle: attachment.vaultNoteTitle } : {}),
+    ...(attachment.previewText !== undefined ? { previewText: attachment.previewText } : {}),
+    ...(attachment.lineCount !== undefined ? { lineCount: attachment.lineCount } : {}),
+  }));
+}
+
+/**
+ * Build the branched "undo last turn" copy of a session.
+ *
+ * The branch keeps the compacted prefix intact (its summary still describes
+ * the kept messages) and drops the external agent session id: external agents
+ * resume provider-side sessions, so the branch must start a fresh one.
+ */
+export function buildUndoLastTurnBranch(
+  source: AISession,
+  options: { newId: string; now: number },
+): UndoLastTurnResult | null {
+  const compactedMessageCount = source.contextCompaction?.compactedMessageCount ?? 0;
+  const boundary = resolveUndoLastTurnBoundary(source.messages, compactedMessageCount);
+  if (boundary == null) return null;
+
+  const removedUserMessage = source.messages[boundary];
+  const retainedPrefix = source.messages.slice(0, boundary);
+  // When undo removes the first turn, the branch has no user message left and
+  // still carries the source title, which was auto-titled from the removed
+  // prompt. Reset it to the untitled placeholder so `autoTitleSession` can
+  // retitle the branch from the prompt the user sends next; otherwise the
+  // branch is permanently labeled with text that is no longer its prompt.
+  // A retained user turn can legitimately carry empty text: a note-only send
+  // leaves `content` blank while the mentioned note rides on the attachment
+  // (and its title) — that turn still anchored the conversation, so it must
+  // keep the note-derived title and suppress the reset.
+  const hasRetainedUserMessage = retainedPrefix.some(
+    message => message.role === 'user',
+  );
+  const branchedSession: AISession = {
+    ...source,
+    id: options.newId,
+    messages: retainedPrefix,
+    ...(hasRetainedUserMessage ? {} : { title: 'New Chat' }),
+    externalSessionId: undefined,
+    createdAt: options.now,
+    updatedAt: options.now,
+  };
+  return {
+    session: branchedSession,
+    restored: {
+      text: removedUserMessage.content,
+      attachments: buildRestoredAttachments(removedUserMessage, options.now),
+      // The undone turn was selected with these skill pills: they shaped the
+      // model context, so resending the turn must not silently omit them.
+      selectedUserSkillSlugs: [...(removedUserMessage.selectedUserSkillSlugs ?? [])],
+    },
+  };
+}

domain/groupConfig.test.ts

@@ -59,6 +59,12 @@ test("applyGroupDefaults lets host device type override group device type", () =
   assert.equal(result.deviceType, "general");
 });
 
+test("applyGroupDefaults skips remote-only device type for local shell hosts", () => {
+  const result = applyGroupDefaults(host({ protocol: "local" }), { deviceType: "network" });
+
+  assert.equal(result.deviceType, undefined);
+});
+
 test("applyGroupDefaults inherits startup command run mode", () => {
   const result = applyGroupDefaults(host(), { startupCommandRunMode: "paste" });
 
@@ -638,3 +644,87 @@ test("applyGroupDefaults still inherits non-credential defaults into serial host
   assert.equal(result.username, undefined);
   assert.equal(result.charset, "UTF-8");
 });
+
+test("applyGroupDefaults does not inherit group SSH credentials into local shell hosts", () => {
+  const groupDefaults: Partial<GroupConfig> = {
+    username: "group-ssh-user",
+    password: "group-ssh-password",
+    savePassword: true,
+    authMethod: "password",
+    identityId: "identity-1",
+    identityFileId: "identity-file-1",
+  };
+
+  const result = applyGroupDefaults(
+    host({ protocol: "local", username: undefined, password: undefined }),
+    groupDefaults,
+  );
+
+  assert.equal(result.username, undefined);
+  assert.equal(result.password, undefined);
+  assert.equal(result.savePassword, undefined);
+  assert.equal(result.authMethod, undefined);
+  assert.equal(result.identityId, undefined);
+  assert.equal(result.identityFileId, undefined);
+});
+
+test("applyGroupDefaults does not inherit SSH transport/input defaults into local shell hosts", () => {
+  const groupDefaults: Partial<GroupConfig> = {
+    backspaceBehavior: "ctrl-h",
+    moshEnabled: true,
+    moshServerPath: "/usr/bin/mosh-server",
+    etEnabled: true,
+    etPort: 8737,
+    legacyAlgorithms: true,
+    skipEcdsaHostKey: true,
+    agentForwarding: true,
+    hostChain: { hostIds: ["bastion-1"] },
+    charset: "UTF-8",
+    fontSize: 14,
+  };
+
+  const result = applyGroupDefaults(
+    host({
+      protocol: "local",
+      backspaceBehavior: undefined,
+      algorithms: undefined,
+      charset: undefined,
+      fontSize: undefined,
+    }),
+    groupDefaults,
+  );
+
+  assert.equal(result.backspaceBehavior, undefined);
+  assert.equal(result.moshEnabled, undefined);
+  assert.equal(result.moshServerPath, undefined);
+  assert.equal(result.etEnabled, undefined);
+  assert.equal(result.etPort, undefined);
+  assert.equal(result.legacyAlgorithms, undefined);
+  assert.equal(result.skipEcdsaHostKey, undefined);
+  assert.equal(result.agentForwarding, undefined);
+  assert.equal(result.hostChain, undefined);
+  // Display/appearance defaults still apply to local shells.
+  assert.equal(result.charset, "UTF-8");
+  assert.equal(result.fontSize, 14);
+});
+
+test("applyGroupDefaults still inherits non-credential defaults into local shell hosts", () => {
+  const result = applyGroupDefaults(
+    host({ protocol: "local", username: undefined, charset: undefined, fontSize: undefined }),
+    { username: "group-ssh-user", charset: "UTF-8", fontSize: 14 },
+  );
+
+  assert.equal(result.username, undefined);
+  assert.equal(result.charset, "UTF-8");
+  assert.equal(result.fontSize, 14);
+});
+
+test("applyGroupDefaults does not inherit the group startup command into local shell hosts", () => {
+  const result = applyGroupDefaults(
+    host({ protocol: "local" }),
+    { startupCommand: "rm -rf /", startupCommandRunMode: "paste" },
+  );
+
+  assert.equal(result.startupCommand, undefined);
+  assert.equal(result.startupCommandRunMode, "paste");
+});

domain/groupConfig.ts

@@ -176,6 +176,25 @@ const SSH_CREDENTIAL_KEYS = new Set<keyof GroupConfig>([
   'identityFilePaths',
 ]);
 
+// SSH transport/input settings the local-shell editor does not expose: input
+// remapping (backspace), Mosh/Eternal-Terminal transports, and SSH-only
+// algorithm/agent/chain flags. A local shell never runs through SSH, so these
+// defaults would either remap local PTY input (`backspaceBehavior`,
+// createXTermRuntime) or make flag-first consumers report a purely local
+// session as Mosh/ET — with no way to override them in the local editor.
+const SSH_ONLY_TRANSPORT_KEYS = new Set<keyof GroupConfig>([
+  'agentForwarding',
+  'legacyAlgorithms',
+  'skipEcdsaHostKey',
+  'algorithms',
+  'hostChain',
+  'moshEnabled',
+  'moshServerPath',
+  'etEnabled',
+  'etPort',
+  'backspaceBehavior',
+]);
+
 /**
  * Apply group defaults to a host. Only fills in fields the host doesn't already have.
  * Returns a new host object — does NOT mutate the original.
@@ -217,9 +236,21 @@ export function applyGroupDefaults(
   // group's SSH password to anything that prints a login prompt.
   const isSerialHost = host.protocol === 'serial';
 
+  // Local-shell hosts run on the user's own machine. Group defaults are
+  // SSH/remote-oriented: the SSH credential bundle and a saved startup
+  // command were written for the group's remote hosts and must never be
+  // inherited into a local shell, or clicking a local entry would
+  // type/execute that command on the local machine — and "Copy Credentials"
+  // on a local shell would copy an unrelated remote password. `deviceType`
+  // is equally remote-only: a saved "network" device type would make a
+  // local CMD/PowerShell/POSIX shell be treated as a network-device CLI
+  // (no normal autocomplete, network semantics for AI/command execution).
+  const isLocalShellHost = host.protocol === 'local';
+
   for (const key of INHERITABLE_KEYS) {
     if (shouldSkipGroupSshCredentialBundle && SSH_CREDENTIAL_KEYS.has(key)) continue;
     if (isSerialHost && SSH_CREDENTIAL_KEYS.has(key)) continue;
+    if (isLocalShellHost && (SSH_CREDENTIAL_KEYS.has(key) || SSH_ONLY_TRANSPORT_KEYS.has(key) || key === 'startupCommand' || key === 'deviceType')) continue;
     if (key === 'password' && effective.savePassword === false) continue;
     if (key === 'telnetIdentityId' && hostHasManualTelnetCredentials) continue;
     if (key === 'proxyProfileId') {

domain/hostOpenSession.test.ts

@@ -0,0 +1,31 @@
+import assert from 'node:assert/strict';
+import { test } from 'node:test';
+import type { TerminalSession } from './models';
+import { findReusableHostSession } from './hostOpenSession';
+
+function tab(id: string, status: TerminalSession['status'], extra: Partial<TerminalSession> = {}): TerminalSession {
+  return { id, hostId: 'host-1', hostLabel: 'Host', hostname: 'example.invalid', username: 'user', status, ...extra };
+}
+
+test('host reuse prefers a connected tab over a connecting tab for the same host', () => {
+  assert.deepEqual(findReusableHostSession([
+    tab('other-host', 'connected', { hostId: 'host-2' }),
+    tab('retrying', 'connecting'),
+    tab('live', 'connected'),
+  ], 'host-1'), { sessionId: 'live', connected: true });
+});
+
+test('host reuse keeps the same tab during the reconnect delay and connection attempt', () => {
+  assert.deepEqual(findReusableHostSession([tab('retrying', 'connecting')], 'host-1'), {
+    sessionId: 'retrying', connected: false,
+  });
+});
+
+test('host reuse excludes restored placeholders and inactive disconnected tabs', () => {
+  assert.equal(findReusableHostSession([
+    tab('manual-disconnect', 'disconnected'),
+    tab('restored', 'disconnected', { restoreState: 'restored-disconnected' }),
+    tab('restoring', 'connecting', { restoreState: 'restored-disconnected' }),
+  ], 'host-1'), undefined);
+  assert.equal(findReusableHostSession([tab('live', 'connected')], ''), undefined);
+});

domain/hostOpenSession.ts

@@ -0,0 +1,14 @@
+import type { TerminalSession } from './models';
+
+export function findReusableHostSession(sessions: TerminalSession[], hostId: string) {
+  if (!hostId) return undefined;
+  // Auto-reconnect publishes connecting even during the retry delay. A plain
+  // disconnected/restored tab needs user action and cannot satisfy host_open.
+  const matches = sessions.filter((session) => (
+    session.hostId === hostId
+    && session.restoreState !== 'restored-disconnected'
+    && (session.status === 'connected' || session.status === 'connecting')
+  ));
+  const picked = matches.find((session) => session.status === 'connected') ?? matches[0];
+  return picked ? { sessionId: picked.id, connected: picked.status === 'connected' } : undefined;
+}

domain/keywordHighlight.test.ts

@@ -149,3 +149,48 @@ test("normalize keeps custom (non-built-in) rules verbatim", () => {
   assert.deepEqual(rule.patterns, customRule.patterns);
   assert.equal(rule.label, customRule.label);
 });
+
+test("Unix path highlighting covers terminal paths without matching relative prose or URL slashes", () => {
+  const rule = getRule(DEFAULT_KEYWORD_HIGHLIGHT_RULES, "unix-path");
+  for (const path of ["/sbin/iptables", "/var/log/syslog", "/usr/local/bin/g++", "~/projects/netcatty"]) {
+    const matches = [...`'${path}'`.matchAll(new RegExp(rule.patterns[0], "gi"))];
+    assert.deepEqual(matches.map((match) => match[0]), [path]);
+  }
+  for (const text of ["RELATED,ESTABLISHED", "TCP/IP", "https://example.com/log", " / ", "./foo", "../foo", "../../foo"]) {
+    assert.equal(matchesAny(rule.patterns, text), false, text);
+  }
+});
+
+test("Unix path rule upgrades old settings while preserving disabled highlights and edits", () => {
+  const legacy = DEFAULT_KEYWORD_HIGHLIGHT_RULES.filter((rule) => rule.id !== "unix-path");
+  const upgraded = normalizeTerminalSettings({ keywordHighlightEnabled: false, keywordHighlightRules: legacy });
+  assert.equal(upgraded.keywordHighlightEnabled, false);
+  assert.equal(getRule(upgraded.keywordHighlightRules, "unix-path").enabled, true);
+
+  const edited = { ...getRule(upgraded.keywordHighlightRules, "unix-path"), color: "#123456", enabled: false, customized: true, patterns: ["/chosen/path"] };
+  const restored = normalizeTerminalSettings({ keywordHighlightRules: [...legacy, edited] });
+  assert.deepEqual(getRule(restored.keywordHighlightRules, "unix-path"), edited);
+});
+
+test("Unix path highlighting keeps Unicode paths and quoted spaces together", () => {
+  const rule = getRule(DEFAULT_KEYWORD_HIGHLIGHT_RULES, "unix-path");
+  for (const [text, path] of [
+    ["/home/用户/file", "/home/用户/file"],
+    ['cat "/Users/me/My Projects/app"', "/Users/me/My Projects/app"],
+    ["cat '/home/用户/My Projects/app'", "/home/用户/My Projects/app"],
+  ]) {
+    const matches = [...text.matchAll(new RegExp(rule.patterns[0], "gi"))];
+    assert.deepEqual(matches.map((match) => match[0]), [path]);
+  }
+});
+
+test("Unix path highlighting keeps punctuation up to the text boundary", () => {
+  const rule = getRule(DEFAULT_KEYWORD_HIGHLIGHT_RULES, "unix-path");
+  for (const path of [
+    "/run/user/1000/gvfs/smb-share:server=nas,share=files/report.txt",
+    "/tmp/build=release/output",
+  ]) {
+    const matches = [...path.matchAll(new RegExp(rule.patterns[0], "gi"))];
+    assert.deepEqual(matches.map((match) => match[0]), [path]);
+  }
+});

domain/localShellHost.test.ts

@@ -0,0 +1,94 @@
+import assert from 'node:assert/strict';
+import { test } from 'node:test';
+import {
+  createLocalShellHost,
+  getLocalShellHostSubtitle,
+  getVaultHostRowSubtitle,
+  resolveHostDefaultLocalShell,
+} from './localShellHost';
+
+test('createLocalShellHost builds a grouped local-protocol host', () => {
+  const host = createLocalShellHost({
+    label: 'Project A CMD',
+    shell: 'powershell',
+    shellName: 'Windows PowerShell',
+    shellIcon: 'powershell',
+    group: 'Projects/A',
+    startDir: ' /home/user/work ',
+    tags: ['local', 'build'],
+  });
+
+  assert.equal(host.protocol, 'local');
+  assert.equal(host.hostname, 'localhost');
+  assert.equal(host.username, '');
+  assert.equal(host.label, 'Project A CMD');
+  assert.equal(host.group, 'Projects/A');
+  assert.equal(host.localShell, 'powershell');
+  assert.equal(host.localShellName, 'Windows PowerShell');
+  assert.equal(host.localShellIcon, 'powershell');
+  assert.equal(host.localStartDir, '/home/user/work');
+  assert.deepEqual(host.tags, ['local', 'build']);
+  assert.ok(host.id.startsWith('local-'));
+});
+
+test('createLocalShellHost falls back to defaults for empty input', () => {
+  const host = createLocalShellHost({});
+  assert.equal(host.label, 'Local Shell');
+  assert.equal(host.localShell, undefined);
+  assert.equal(host.localShellName, undefined);
+  assert.equal(host.localStartDir, undefined);
+  assert.deepEqual(host.tags, ['local']);
+  assert.equal(host.group, '');
+  assert.equal(host.os, 'linux');
+});
+
+test('createLocalShellHost preserves explicit id when editing', () => {
+  const host = createLocalShellHost({ id: 'local-existing', label: 'Renamed' });
+  assert.equal(host.id, 'local-existing');
+});
+
+test('getVaultHostRowSubtitle uses shell name for local hosts', () => {
+  assert.equal(
+    getVaultHostRowSubtitle({ protocol: 'local', localShellName: 'CMD', username: '', hostname: 'localhost' }),
+    'CMD',
+  );
+  assert.equal(
+    getVaultHostRowSubtitle({ protocol: 'local', username: '', hostname: 'localhost' }),
+    'Local Shell',
+  );
+  assert.equal(
+    getVaultHostRowSubtitle(
+      { protocol: 'local', username: '', hostname: 'localhost' },
+      { localFallback: '本地终端' },
+    ),
+    '本地终端',
+  );
+});
+
+test('getVaultHostRowSubtitle keeps user@host for remote hosts', () => {
+  assert.equal(
+    getVaultHostRowSubtitle({ protocol: 'ssh', username: 'root', hostname: 'example.com' }),
+    'root@example.com',
+  );
+  assert.equal(
+    getVaultHostRowSubtitle({ protocol: 'telnet', username: '', hostname: '10.0.0.1' }),
+    '@10.0.0.1',
+  );
+});
+
+test('getLocalShellHostSubtitle ignores whitespace-only names and allows a fallback', () => {
+  assert.equal(getLocalShellHostSubtitle({ protocol: 'local', localShellName: '  ' }), 'Local Shell');
+  assert.equal(
+    getLocalShellHostSubtitle({ protocol: 'local', localShellName: '' }, '本地终端'),
+    '本地终端',
+  );
+});
+
+test('clearing the configured executable does not pass its old custom args to the backend default', () => {
+  const effective = resolveHostDefaultLocalShell(createLocalShellHost({}), {
+    terminalSettings: { localShell: '', localShellArgs: ['--norc'] },
+    resolveShellSetting: () => null,
+  });
+  assert.equal(effective.localShell, '');
+  assert.equal(effective.localShellArgs, undefined);
+});

domain/localShellHost.ts

@@ -0,0 +1,107 @@
+import type { Host } from './models';
+
+/**
+ * Vault-side "local shell" (CMD / PowerShell / WSL / custom shell) host entry.
+ *
+ * A vault host with protocol 'local' is grouped, sorted and connected exactly
+ * like any other saved host: clicking it opens a terminal session whose boot
+ * path resolves the host's stored shell (see `startLocal` in
+ * `createTerminalSessionStarters` and the bridge resolution of discovered
+ * shell ids).
+ */
+
+export type LocalShellHostOs = 'linux' | 'windows' | 'macos';
+
+export interface LocalShellHostInput {
+  id?: string;
+  os?: LocalShellHostOs;
+  label?: string;
+  /** Discovered shell id (e.g. "wsl-ubuntu") or a custom shell path/command. Empty = system default. */
+  shell?: string;
+  shellArgs?: string[];
+  shellName?: string;
+  shellIcon?: string;
+  startDir?: string;
+  group?: string;
+  tags?: string[];
+  notes?: string;
+}
+
+export const LOCAL_SHELL_HOST_TAG = 'local';
+
+export const createLocalShellHost = (input: LocalShellHostInput): Host => ({
+  id: input.id ?? `local-${Date.now()}-${Math.random().toString(36).substring(2, 11)}`,
+  label: input.label?.trim() || input.shellName?.trim() || 'Local Shell',
+  hostname: 'localhost',
+  username: '',
+  tags: input.tags ?? [LOCAL_SHELL_HOST_TAG],
+  group: input.group?.trim() || '',
+  os: input.os ?? 'linux',
+  protocol: 'local',
+  createdAt: Date.now(),
+  notes: input.notes?.trim() || undefined,
+  localShell: input.shell?.trim() || undefined,
+  localShellArgs: input.shellArgs?.length ? input.shellArgs : undefined,
+  localShellName: input.shellName?.trim() || undefined,
+  localShellIcon: input.shellIcon?.trim() || undefined,
+  localStartDir: input.startDir?.trim() || undefined,
+});
+
+/** What an existing vault host shows as its local-shell display name. */
+export const getLocalShellHostSubtitle = (
+  host: Pick<Host, 'protocol' | 'localShellName'>,
+  fallback = 'Local Shell',
+): string => host.localShellName?.trim() || fallback;
+
+export interface VaultHostRowSubtitleOptions {
+  /** Translated fallback shown for default-shell local hosts. */
+  localFallback?: string;
+}
+
+/** Row subtitle shared by the vault tree rows and host cards. */
+export const getVaultHostRowSubtitle = (
+  host: Pick<Host, 'protocol' | 'localShellName' | 'username' | 'hostname'>,
+  options?: VaultHostRowSubtitleOptions,
+): string => (
+  host.protocol === 'local'
+    ? getLocalShellHostSubtitle(host, options?.localFallback)
+    : `${host.username ?? ''}@${host.hostname ?? ''}`
+);
+
+export interface ResolveDefaultLocalShellContext {
+  discoveredShells?: DiscoveredShell[];
+  terminalSettings?: { localShell?: string; localShellArgs?: string[]; localStartDir?: string };
+  resolveShellSetting?: (
+    localShell: string,
+    discoveredShells: DiscoveredShell[],
+    customArgs?: string[],
+  ) => { command: string; args?: string[] } | null;
+}
+
+/** Resolve launch settings before a local session snapshots them. */
+export const resolveHostDefaultLocalShell = (
+  host: Host,
+  ctx: ResolveDefaultLocalShellContext,
+): Host => {
+  if (host.protocol !== 'local') return host;
+  const configuredShell = host.localShell || ctx.terminalSettings?.localShell || '';
+  const customArgs = host.localShell
+    ? host.localShellArgs
+    : configuredShell ? ctx.terminalSettings?.localShellArgs : undefined;
+  const resolved = ctx.resolveShellSetting?.(
+    configuredShell, ctx.discoveredShells ?? [], customArgs,
+  );
+  const matchedShell = ctx.discoveredShells?.find((shell) => shell.id === configuredShell);
+  return {
+    ...host,
+    // Empty means the backend default, not a later Vault/Settings value.
+    localShell: resolved?.command || configuredShell || '',
+    localShellArgs: resolved?.args ?? customArgs,
+    localShellName: host.localShell ? host.localShellName : matchedShell?.name,
+    localShellIcon: host.localShell ? host.localShellIcon : matchedShell?.icon,
+    // The existing launcher expands ~ to home. Capture it explicitly when
+    // neither host nor Settings supplies a directory, so a later global edit
+    // cannot change a copied session's original launch directory.
+    localStartDir: host.localStartDir || ctx.terminalSettings?.localStartDir || '~',
+  };
+};

domain/models/terminal.ts

@@ -288,6 +288,7 @@ export const DEFAULT_KEYWORD_HIGHLIGHT_RULES: KeywordHighlightRule[] = [
   { id: 'info', label: 'Info', patterns: ['\\[info\\]', '\\[notice\\]', '\\[note\\]', '\\bnotice\\b', '\\bnote\\b'], color: '#3B82F6', enabled: true },
   { id: 'debug', label: 'Debug', patterns: ['\\[debug\\]', '\\[trace\\]', '\\[verbose\\]', '\\bdebug\\b', '\\btrace\\b', '\\bverbose\\b'], color: '#A78BFA', enabled: true },
   { id: 'ip-mac', label: 'URL, IP & MAC', patterns: [URL_HIGHLIGHT_PATTERN, IPV4_HIGHLIGHT_PATTERN, IPV6_HIGHLIGHT_PATTERN, MAC_ADDRESS_HIGHLIGHT_PATTERN], color: '#EC4899', enabled: true },
+  { id: 'unix-path', label: 'Unix paths', patterns: ["(?<=\")(?:/|~/)[^\"\\r\\n]+(?=\")|(?<=')(?:/|~/)[^'\\r\\n]+(?=')|(?<![\\w.:/\"'\\u0080-\\uFFFF])(?:/|~/)[^\\s\"']+"], color: '#A78BFA', enabled: true },
 ];
 
 const cloneKeywordHighlightRule = (rule: KeywordHighlightRule): KeywordHighlightRule => ({

domain/sessionRestore.test.ts

@@ -864,3 +864,32 @@ test("resolveInheritedCwdIntent: skips mosh/et and network devices and bad paths
 test("resolveInheritedCwdIntent: skips windows local shells", () => {
   assert.equal(resolveInheritedCwdIntent({ session: { protocol: "local", shellType: "powershell", cwd: "/x" }, isNetworkDevice: false }), null);
 });
+
+test("restore retains an explicit backend-default local shell snapshot", () => {
+  const payload = buildSessionRestorePayload({
+    sessions: [{ ...session("local-default"), protocol: "local", localShell: "", localShellArgs: [], localStartDir: "~" }],
+    workspaces: [], tabOrder: [], activeTabId: "local-default", now: 123,
+  });
+  const restored = sanitizeSessionRestorePayload(JSON.parse(JSON.stringify(payload)));
+  assert.equal(restored.sessions[0].localShell, "");
+  assert.deepEqual(restored.sessions[0].localShellArgs, []);
+  assert.equal(restored.sessions[0].localStartDir, "~");
+});
+
+test("restore retains absent local display snapshots while legacy fields remain absent", () => {
+  const payload = buildSessionRestorePayload({
+    sessions: [
+      { ...session("empty-display"), protocol: "local", localShellName: "", localShellIcon: "" },
+      { ...session("named-display"), protocol: "local", localShellName: "Bash", localShellIcon: "bash" },
+      { ...session("legacy-display"), protocol: "local" },
+    ],
+    workspaces: [], tabOrder: [], activeTabId: "empty-display", now: 123,
+  });
+  const restored = sanitizeSessionRestorePayload(JSON.parse(JSON.stringify(payload)));
+  assert.equal(restored.sessions[0].localShellName, "");
+  assert.equal(restored.sessions[0].localShellIcon, "");
+  assert.equal(restored.sessions[1].localShellName, "Bash");
+  assert.equal(restored.sessions[1].localShellIcon, "bash");
+  assert.equal(restored.sessions[2].localShellName, undefined);
+  assert.equal(restored.sessions[2].localShellIcon, undefined);
+});

domain/sessionRestore.ts

@@ -152,10 +152,10 @@ const restoreSession = (session: TerminalSession): RestoredTerminalSession => {
     ...(shellType ? { shellType } : {}),
     ...(session.charset ? { charset: session.charset } : {}),
     ...(serialConfig ? { serialConfig } : {}),
-    ...(session.localShell ? { localShell: session.localShell } : {}),
+    ...(session.localShell !== undefined ? { localShell: session.localShell } : {}),
     ...(session.localShellArgs ? { localShellArgs: [...session.localShellArgs] } : {}),
-    ...(session.localShellName ? { localShellName: session.localShellName } : {}),
-    ...(session.localShellIcon ? { localShellIcon: session.localShellIcon } : {}),
+    ...(session.localShellName !== undefined ? { localShellName: session.localShellName } : {}),
+    ...(session.localShellIcon !== undefined ? { localShellIcon: session.localShellIcon } : {}),
     ...(session.localStartDir ? { localStartDir: session.localStartDir } : {}),
     ...(session.fontSize !== undefined ? { fontSize: session.fontSize } : {}),
     ...(session.fontSizeOverride !== undefined ? { fontSizeOverride: session.fontSizeOverride } : {}),
@@ -195,10 +195,10 @@ const restoreSessionFromUnknown = (value: unknown): RestoredTerminalSession | nu
     ...(shellType ? { shellType } : {}),
     ...(readString(value, "charset") ? { charset: readString(value, "charset") } : {}),
     ...(serialConfig ? { serialConfig } : {}),
-    ...(readString(value, "localShell") ? { localShell: readString(value, "localShell") } : {}),
+    ...(readStringAllowEmpty(value, "localShell") !== undefined ? { localShell: readStringAllowEmpty(value, "localShell") } : {}),
     ...(Array.isArray(value.localShellArgs) ? { localShellArgs: value.localShellArgs.filter((arg): arg is string => typeof arg === "string") } : {}),
-    ...(readString(value, "localShellName") ? { localShellName: readString(value, "localShellName") } : {}),
-    ...(readString(value, "localShellIcon") ? { localShellIcon: readString(value, "localShellIcon") } : {}),
+    ...(readStringAllowEmpty(value, "localShellName") !== undefined ? { localShellName: readStringAllowEmpty(value, "localShellName") } : {}),
+    ...(readStringAllowEmpty(value, "localShellIcon") !== undefined ? { localShellIcon: readStringAllowEmpty(value, "localShellIcon") } : {}),
     ...(readString(value, "localStartDir") ? { localStartDir: readString(value, "localStartDir") } : {}),
     ...(readNumber(value, "fontSize") !== undefined ? { fontSize: readNumber(value, "fontSize") } : {}),
     ...(readBoolean(value, "fontSizeOverride") !== undefined ? { fontSizeOverride: readBoolean(value, "fontSizeOverride") } : {}),

domain/sftpDualPaneOpen.ts

@@ -46,6 +46,9 @@ export type DualPaneSftpPlan = {
 export function canOpenDualPaneSftp(host: { protocol?: string }): boolean {
   const protocol = host.protocol ?? "ssh";
   if (protocol === "serial") return false;
+  // Local-shell vault hosts have no SFTP/SSH channel: opening dual-pane SFTP
+  // from one would try to SSH into localhost with empty credentials.
+  if (protocol === "local") return false;
   if (isPluginHostProtocol(protocol)) return false;
   return true;
 }

domain/terminalHostResolution.test.ts

@@ -173,6 +173,79 @@ test("resolveTerminalSessionHost keeps the session plugin configuration when the
   });
 });
 
+test("resolveTerminalSessionHost preserves the session local-shell snapshot over an edited Vault host", () => {
+  const host: Host = {
+    id: "target",
+    label: "Edited PowerShell",
+    hostname: "localhost",
+    username: "local",
+    protocol: "local",
+    tags: [],
+    os: "windows",
+    localShell: "powershell.exe",
+    localShellArgs: ["-NoLogo"],
+    localShellName: "PowerShell",
+    localShellIcon: "powershell",
+    localStartDir: "C:/edited",
+  };
+
+  const resolved = resolveTerminalSessionHost({
+    session: {
+      ...baseSession,
+      hostname: "localhost",
+      username: "local",
+      port: undefined,
+      protocol: "local",
+      localShell: "cmd.exe",
+      localShellArgs: [],
+      localShellName: "Command Prompt",
+      localShellIcon: "cmd",
+      localStartDir: "C:/project",
+    },
+    hosts: [host],
+    groupConfigs: [],
+    proxyProfiles,
+    localOs: "windows",
+  });
+
+  assert.equal(resolved.localShell, "cmd.exe");
+  assert.deepEqual(resolved.localShellArgs, []);
+  assert.equal(resolved.localShellName, "Command Prompt");
+  assert.equal(resolved.localShellIcon, "cmd");
+  assert.equal(resolved.localStartDir, "C:/project");
+});
+
+test("resolveTerminalSessionHost falls back to the saved local shell when the session has no snapshot", () => {
+  const host: Host = {
+    id: "target",
+    label: "Local Shell",
+    hostname: "localhost",
+    username: "local",
+    protocol: "local",
+    tags: [],
+    os: "windows",
+    localShell: "powershell.exe",
+    localShellName: "PowerShell",
+  };
+
+  const resolved = resolveTerminalSessionHost({
+    session: {
+      ...baseSession,
+      hostname: "localhost",
+      username: "local",
+      port: undefined,
+      protocol: "local",
+    },
+    hosts: [host],
+    groupConfigs: [],
+    proxyProfiles,
+    localOs: "windows",
+  });
+
+  assert.equal(resolved.localShell, "powershell.exe");
+  assert.equal(resolved.localShellName, "PowerShell");
+});
+
 test("resolveTerminalSessionHost carries local session start directory into fallback host", () => {
   const resolved = resolveTerminalSessionHost({
     session: {
@@ -488,3 +561,77 @@ test("resolveTerminalChainHosts applies group default proxy profiles to jump hos
   assert.equal(resolved[0]?.proxyProfileId, "proxy-1");
   assert.deepEqual(resolved[0]?.proxyConfig, proxyProfiles[0].config);
 });
+
+test("resolveTerminalChainHosts skips non-SSH jump candidates", () => {
+  const target: Host = {
+    id: "target",
+    label: "Target",
+    hostname: "target.example.test",
+    username: "alice",
+    port: 22,
+    protocol: "ssh",
+    tags: [],
+    os: "linux",
+    hostChain: { hostIds: ["jump-local", "jump-serial", "jump-telnet", "jump-ssh", "jump-mosh"] },
+  };
+  const localHost: Host = {
+    id: "jump-local",
+    label: "Local Shell",
+    hostname: "localhost",
+    username: "",
+    port: 22,
+    protocol: "local",
+    tags: [],
+    os: "linux",
+  };
+  const serialHost: Host = {
+    id: "jump-serial",
+    label: "Serial",
+    hostname: "/dev/ttyUSB0",
+    username: "",
+    port: 22,
+    protocol: "serial",
+    tags: [],
+    os: "linux",
+  };
+  const telnetHost: Host = {
+    id: "jump-telnet",
+    label: "Telnet",
+    hostname: "telnet.example.test",
+    username: "bob",
+    port: 23,
+    protocol: "telnet",
+    tags: [],
+    os: "linux",
+  };
+  const sshHost: Host = {
+    id: "jump-ssh",
+    label: "Jump SSH",
+    hostname: "jump.example.test",
+    username: "jump",
+    port: 22,
+    protocol: "ssh",
+    tags: [],
+    os: "linux",
+  };
+  const moshHost: Host = {
+    id: "jump-mosh",
+    label: "Jump Mosh",
+    hostname: "mosh.example.test",
+    username: "jump",
+    port: 22,
+    protocol: "ssh",
+    moshEnabled: true,
+    tags: [],
+    os: "linux",
+  };
+
+  const resolved = resolveTerminalChainHosts({
+    host: target,
+    hosts: [target, localHost, serialHost, telnetHost, sshHost, moshHost],
+    groupConfigs: [],
+    proxyProfiles,
+  });
+
+  assert.deepEqual(resolved.map((host) => host.id), ["jump-ssh", "jump-mosh"]);
+});

domain/terminalHostResolution.ts

@@ -2,6 +2,8 @@ import type { GroupConfig, Host, ProxyProfile, TerminalSession } from "./models"
 import { applyGroupDefaults, resolveGroupDefaults } from "./groupConfig";
 import { materializeHostProxyProfile } from "./proxyProfiles";
 import { sanitizePluginConnection } from "./pluginConnection";
+import { resolveHostDefaultLocalShell, type ResolveDefaultLocalShellContext } from "./localShellHost";
+import { canServeAsSshJumpHost } from "./terminalProtocol";
 
 type LocalOs = Host["os"];
 
@@ -10,6 +12,8 @@ interface ResolveEffectiveHostOptions {
   groupConfigs: GroupConfig[];
   proxyProfiles: ProxyProfile[];
   validProxyProfileIds?: ReadonlySet<string>;
+  /** When provided, saved local hosts with no shell resolve the Settings shell. */
+  defaultLocalShell?: ResolveDefaultLocalShellContext;
 }
 
 interface ResolveTerminalSessionHostOptions {
@@ -18,6 +22,8 @@ interface ResolveTerminalSessionHostOptions {
   groupConfigs: GroupConfig[];
   proxyProfiles: ProxyProfile[];
   localOs: LocalOs;
+  /** When provided, saved local hosts with no shell resolve the Settings shell. */
+  defaultLocalShell?: ResolveDefaultLocalShellContext;
 }
 
 interface ResolveTerminalChainHostsOptions {
@@ -41,14 +47,18 @@ export function resolveEffectiveTerminalHost({
   groupConfigs,
   proxyProfiles,
   validProxyProfileIds = new Set(proxyProfiles.map((profile) => profile.id)),
+  defaultLocalShell,
 }: ResolveEffectiveHostOptions): Host {
   const groupDefaults = host.group
     ? resolveGroupDefaults(host.group, groupConfigs, { validProxyProfileIds })
     : {};
-  return materializeHostProxyProfile(
+  const effectiveHost = materializeHostProxyProfile(
     applyGroupDefaults(host, groupDefaults, { validProxyProfileIds }),
     proxyProfiles,
   );
+  return defaultLocalShell
+    ? resolveHostDefaultLocalShell(effectiveHost, defaultLocalShell)
+    : effectiveHost;
 }
 
 const suppressDeviceTypeForShellTransport = (host: Host): Host => {
@@ -86,12 +96,30 @@ function buildFallbackHostFromSession(
   };
 }
 
+// A local session carries a shell snapshot (shell path, args, name, icon,
+// start dir) captured at launch time; the saved host may have been edited
+// since. Popup/clone flows must relaunch the session's shell, not the host's
+// current one, so overlay the snapshot onto the resolved host.
+const overlaySessionLocalShell = (session: TerminalSession, host: Host): Host => {
+  if (session.protocol !== "local") return host;
+  return {
+    ...host,
+    username: session.username,
+    localShell: session.localShell ?? host.localShell,
+    localShellArgs: session.localShellArgs ?? host.localShellArgs,
+    localShellName: session.localShellName ?? host.localShellName,
+    localShellIcon: session.localShellIcon ?? host.localShellIcon,
+    localStartDir: session.localStartDir ?? host.localStartDir,
+  };
+};
+
 export function resolveTerminalSessionHost({
   session,
   hosts,
   groupConfigs,
   proxyProfiles,
   localOs,
+  defaultLocalShell,
 }: ResolveTerminalSessionHostOptions): Host {
   const vaultHost = hosts.find((host) => host.id === session.hostId);
   if (!vaultHost) return buildFallbackHostFromSession(session, localOs);
@@ -100,6 +128,7 @@ export function resolveTerminalSessionHost({
     host: vaultHost,
     groupConfigs,
     proxyProfiles,
+    defaultLocalShell,
   });
 
   const protocol = session.protocol ?? existingHost.protocol;
@@ -126,10 +155,12 @@ export function resolveTerminalSessionHost({
     JSON.stringify(pluginConnection) === JSON.stringify(existingHost.pluginConnection) &&
     backspaceBehavior === existingHost.backspaceBehavior
   ) {
-    return suppressDeviceTypeForShellTransport(existingHost);
+    return suppressDeviceTypeForShellTransport(
+      overlaySessionLocalShell(session, existingHost),
+    );
   }
 
-  return suppressDeviceTypeForShellTransport({
+  return suppressDeviceTypeForShellTransport(overlaySessionLocalShell(session, {
     ...existingHost,
     protocol,
     port,
@@ -137,7 +168,7 @@ export function resolveTerminalSessionHost({
     etEnabled,
     pluginConnection,
     backspaceBehavior,
-  });
+  }));
 }
 
 export function resolveTerminalChainHosts({
@@ -152,7 +183,9 @@ export function resolveTerminalChainHosts({
   return host.hostChain.hostIds
     .map((hostId) => {
       const chainHost = hostMap.get(hostId);
-      if (!chainHost) return undefined;
+      // Jump hops are dialed over SSH; skip local/serial/telnet/plugin entries
+      // that can never serve as a ProxyJump hop (e.g. saved local shells).
+      if (!chainHost || !canServeAsSshJumpHost(chainHost)) return undefined;
       return resolveEffectiveTerminalHost({
         host: chainHost,
         groupConfigs,

domain/terminalProtocol.ts

@@ -11,3 +11,18 @@ export function resolveEffectiveTerminalProtocol(host: TerminalTransportHost): H
   if (host.hostname === 'localhost') return 'local';
   return host.protocol ?? 'ssh';
 }
+
+/**
+ * Whether a vault host can serve as an SSH jump (ProxyJump) hop.
+ *
+ * Chain hops are dialed over SSH, so ssh-family transports (including mosh/et
+ * hosts, which bootstrap over SSH) qualify, while local shells, serial links,
+ * telnet and plugin transports must never be materialized as jump hosts.
+ * Hosts without an explicit protocol are legacy SSH entries.
+ */
+export function canServeAsSshJumpHost(
+  host: Pick<Host, 'protocol'>,
+): boolean {
+  const protocol = host.protocol;
+  return protocol === undefined || protocol === 'ssh' || protocol === 'mosh' || protocol === 'et';
+}

domain/vaultHostCreate.test.ts

@@ -41,6 +41,28 @@ test('buildVaultHostMergeKey treats group as part of session identity', () => {
   );
 });
 
+test('buildVaultHostMergeKey normalizes the local-shell default port', () => {
+  // Vault-editor local hosts omit `port`; CSV export/import round-trips store
+  // the effective default (22). Both forms must dedupe as the same entry.
+  const localBase = {
+    hostname: 'localhost',
+    username: '',
+    protocol: 'local' as const,
+    group: 'lan',
+    os: 'windows' as const,
+    localShellName: 'PowerShell',
+  };
+  assert.equal(
+    buildVaultHostMergeKey({ ...localBase }),
+    buildVaultHostMergeKey({ ...localBase, port: 22 }),
+  );
+  // An explicit non-default port is still a distinct identity.
+  assert.notEqual(
+    buildVaultHostMergeKey({ ...localBase, port: 2222 }),
+    buildVaultHostMergeKey({ ...localBase, port: 22 }),
+  );
+});
+
 test('buildVaultHostFromDraft maps minimal unstructured fields to a vault host', () => {
   const built = buildVaultHostFromDraft({
     hostname: '192.168.1.10',

domain/vaultHostCreate.ts

@@ -185,19 +185,36 @@ const parseKeyPath = (draft: VaultHostDraft): string | undefined => {
 export const buildVaultHostEndpointKey = (
   host: Pick<Host, 'hostname' | 'port' | 'username' | 'protocol'>,
 ): string =>
-  `${(host.protocol ?? 'ssh').toLowerCase()}|${host.hostname.toLowerCase()}|${host.port}|${(host.username ?? '').toLowerCase()}`;
+  // Local-shell hosts created by the vault editor omit `port`, but CSV
+  // export/import round-trips store the effective default (22). Normalize so
+  // a local entry keeps a stable dedupe identity in both forms.
+  `${(host.protocol ?? 'ssh').toLowerCase()}|${host.hostname.toLowerCase()}|${host.protocol === 'local' ? (host.port ?? DEFAULT_SSH_PORT) : host.port}|${(host.username ?? '').toLowerCase()}`;
 
 /**
  * Session identity for vault import/create dedupe.
  * Same endpoint in a different group is a distinct connection (e.g. direct vs proxy copy).
+ * Local-shell entries all share an endpoint key (local|localhost|22|<group>), so
+ * their shell identity (shell, args, name, start dir, OS) is part of the key:
+ * CMD and PowerShell entries in the same group must not collapse or skip each
+ * other during any import dedupe stage.
  */
 export const buildVaultHostMergeKey = (
-  host: Pick<Host, 'hostname' | 'port' | 'username' | 'protocol' | 'group'>,
+  host: Pick<Host, 'hostname' | 'port' | 'username' | 'protocol' | 'group'>
+    & Partial<Pick<Host, 'os' | 'localShell' | 'localShellArgs' | 'localShellName' | 'localStartDir'>>,
 ): string => {
   // Keep normalized group spelling (do not case-fold). Vault group paths are
   // compared exactly elsewhere, so Prod vs prod are distinct sessions.
   const group = normalizeGroupPath(host.group) ?? '';
-  return `${buildVaultHostEndpointKey(host)}|${group}`;
+  const endpointGroupKey = `${buildVaultHostEndpointKey(host)}|${group}`;
+  if (host.protocol !== 'local') return endpointGroupKey;
+  const shellIdentity = [
+    host.os ?? '',
+    host.localShell ?? '',
+    host.localShellName ?? '',
+    host.localShellArgs ? JSON.stringify(host.localShellArgs) : '',
+    host.localStartDir ?? '',
+  ].join('|');
+  return `${endpointGroupKey}|${shellIdentity}`;
 };
 
 export function buildVaultHostFromDraft(

domain/vaultImport.test.ts

@@ -10,7 +10,7 @@ import {
   filterVaultImportKeyPassphrasesAgainstExisting,
   resolveVaultImportKeyPassphraseConflicts,
 } from "./vaultImport.ts";
-import { encodeCsvPassphrase } from "./vaultImport/csvCredentialFields.ts";
+import { encodeCsvPassphrase, encodeCsvLocalShell } from "./vaultImport/csvCredentialFields.ts";
 import type { Host } from "./models.ts";
 
 const mobaXtermSshSession = (
@@ -527,6 +527,73 @@ test("applyVaultImportDestination does not override retained key auth with ident
   assert.equal(targeted.hosts[0]?.identityId, undefined);
 });
 
+test("CSV import keeps default-shell local hosts distinct across OS values", () => {
+  // The merge key for local hosts must include the host OS: two default-shell
+  // entries (no shell/args/name/startDir) in the same group differ only by os,
+  // and dropping the second would silently lose that OS's default shell.
+  const csvQuote = (value: string): string => `"${value.replaceAll('"', '""')}"`;
+  const result = importVaultHostsFromText("csv", [
+    "Label,Hostname,Protocol,Group,LocalShell",
+    `Win,localhost,local,Tools,${csvQuote(encodeCsvLocalShell({ os: "windows" }))}`,
+    `Nix,localhost,local,Tools,${csvQuote(encodeCsvLocalShell({ os: "linux" }))}`,
+  ].join("\n"));
+
+  assert.deepEqual(result.issues, []);
+  assert.equal(result.stats.duplicates, 0);
+  assert.equal(result.hosts.length, 2);
+  assert.deepEqual(
+    result.hosts.map((host) => host.os),
+    ["windows", "linux"],
+  );
+});
+
+test("import destination keeps local shells distinct through the full pipeline", () => {
+  // applyVaultImportDestination re-dedupe and applyVaultHostImport must not
+  // collapse CMD/PowerShell entries back onto the endpoint-only merge key.
+  const csvQuote = (value: string): string => `"${value.replaceAll('"', '""')}"`;
+  const result = importVaultHostsFromText("csv", [
+    "Label,Hostname,Protocol,Group,LocalShell",
+    `CMD,localhost,local,Tools,${csvQuote(encodeCsvLocalShell({ os: "windows", shellName: "CMD" }))}`,
+    `PS,localhost,local,Tools,${csvQuote(encodeCsvLocalShell({ os: "windows", shellName: "PowerShell" }))}`,
+  ].join("\n"));
+  assert.equal(result.hosts.length, 2);
+
+  const targeted = applyVaultImportDestination(result, {
+    mode: "group",
+    group: "Imported",
+  });
+  assert.equal(targeted.hosts.length, 2);
+  assert.deepEqual(
+    targeted.hosts.map((host) => host.localShellName),
+    ["CMD", "PowerShell"],
+  );
+
+  const applied = applyVaultHostImport([], [], targeted);
+  assert.equal(applied.hosts.length, 2);
+  assert.equal(applied.skippedExistingCount, 0);
+
+  // Re-importing the same backup into the same destination must skip both
+  // existing shell entries instead of importing them again.
+  const reapplied = applyVaultHostImport(applied.hosts, [], targeted);
+  assert.equal(reapplied.hosts.length, 2);
+  assert.equal(reapplied.skippedExistingCount, 2);
+});
+
+test("applyVaultHostImport still dedupes identical local shells but keeps different shells", () => {
+  const csvQuote = (value: string): string => `"${value.replaceAll('"', '""')}"`;
+  const result = importVaultHostsFromText("csv", [
+    "Label,Hostname,Protocol,Group,LocalShell",
+    `CMD,localhost,local,Tools,${csvQuote(encodeCsvLocalShell({ os: "windows", shellName: "CMD" }))}`,
+    `PS,localhost,local,Tools,${csvQuote(encodeCsvLocalShell({ os: "windows", shellName: "PowerShell" }))}`,
+  ].join("\n"));
+
+  const existingCmd = result.hosts[0]!;
+  const applied = applyVaultHostImport([existingCmd], [], result);
+  assert.equal(applied.hosts.length, 2);
+  assert.equal(applied.skippedExistingCount, 1);
+  assert.equal(applied.addedHosts[0]?.localShellName, "PowerShell");
+});
+
 test("CSV import keeps working when KeyPath and Passphrase columns are absent", () => {
   const result = importVaultHostsFromText(
     "csv",

domain/vaultImport.ts

@@ -15,7 +15,7 @@ export {
 } from "./vaultHostCreate";
 import { parseQuickConnectInput } from "./quickConnect";
 import { findExactHeaderIndex, findHeaderIndex, parseCsv } from "./vaultImport/csvUtils";
-import { decodeCsvKeyPath, decodeCsvPassphrase } from "./vaultImport/csvCredentialFields";
+import { decodeCsvKeyPath, decodeCsvLocalShell, decodeCsvPassphrase } from "./vaultImport/csvCredentialFields";
 import { parseCsvProxy } from "./vaultImport/csvProxy";
 import { attachMobaXtermPasswords } from "./vaultImport/mobaXtermPasswords";
 import { decodeFinalShellPassword } from "./finalShellPassword";
@@ -326,7 +326,9 @@ const createHost = (input: {
 
 const dedupeHosts = (
   hosts: Host[],
-  options?: { isCollapsible?: (host: Host) => boolean },
+  options?: {
+    isCollapsible?: (host: Host) => boolean;
+  },
 ): { hosts: Host[]; duplicates: number } => {
   const seen = new Map<string, Host>();
   const retained: Host[] = [];
@@ -446,6 +448,7 @@ const importFromCsv = (text: string): VaultImportResult => {
   const keyPathIdx = findExactHeaderIndex(header, ["keypath", "key path", "identityfile", "identity file"]);
   const explicitPassphraseIdx = findExactHeaderIndex(header, ["passphrase", "keypassphrase", "key passphrase"]);
   const proxyIdx = findExactHeaderIndex(header, ["proxy", "proxyserver", "proxy server"]);
+  const localShellIdx = findExactHeaderIndex(header, ["localshell"]);
   const passphraseIdx = keyPathIdx >= 0 ? explicitPassphraseIdx : -1;
   const exactPasswordIdx = findExactHeaderIndex(header, ["password", "pass", "passwd"]);
   const fuzzyNamedPasswordIdx = findHeaderIndex(header, ["password", "passwd"]);
@@ -537,6 +540,15 @@ const importFromCsv = (text: string): VaultImportResult => {
       });
     }
 
+    const localShellRaw = (localShellIdx >= 0 ? row[localShellIdx] : undefined)?.trim();
+    const localShellSpec = localShellRaw ? decodeCsvLocalShell(localShellRaw) : undefined;
+    if (localShellRaw && !localShellSpec) {
+      issues.push({
+        level: "warning",
+        message: `CSV row ${i + 2}: LocalShell was ignored because it is not a valid encoded local-shell value.`,
+      });
+    }
+
     if (decodedPassphrase && isEncryptedCredentialPlaceholder(decodedPassphrase)) {
       issues.push({
         level: "warning",
@@ -564,6 +576,14 @@ const importFromCsv = (text: string): VaultImportResult => {
       notes,
     });
     if (proxyConfig) host.proxyConfig = proxyConfig;
+    if (localShellSpec && protocol === "local") {
+      if (localShellSpec.shell) host.localShell = localShellSpec.shell;
+      if (localShellSpec.shellArgs) host.localShellArgs = localShellSpec.shellArgs;
+      if (localShellSpec.shellName) host.localShellName = localShellSpec.shellName;
+      if (localShellSpec.shellIcon) host.localShellIcon = localShellSpec.shellIcon;
+      if (localShellSpec.startDir) host.localStartDir = localShellSpec.startDir;
+      if (localShellSpec.os) host.os = localShellSpec.os;
+    }
     parsedHosts.push(host);
     if (keyPath && passphrase) {
       const keyPathKey = normalizeKeyPathKey(keyPath);
@@ -586,6 +606,10 @@ const importFromCsv = (text: string): VaultImportResult => {
     }
   }
 
+  // Local-shell entries share the endpoint key (local|localhost|22|<group>), so
+  // the shell identity is part of buildVaultHostMergeKey; otherwise importing a
+  // backup with CMD and PowerShell in the same group silently keeps only the
+  // first shell and flags the rest as duplicates.
   const { hosts, duplicates } = dedupeHosts(parsedHosts);
   const keyPassphrases = hosts.flatMap((host) => {
     const selectedKeyPath = host.identityFilePaths?.find((path) => path.trim())?.trim();

domain/vaultImport/csvCredentialFields.ts

@@ -2,6 +2,7 @@ const FORMULA_PREFIX = /^[=+\-@\t\r]/u;
 const KEY_PATH_MARKER = "__netcatty_csv_keypath_v1__:";
 const PASSPHRASE_MARKER = "__netcatty_csv_passphrase_v1__:";
 const PROXY_MARKER = "__netcatty_csv_proxy_v1__:";
+const LOCAL_SHELL_MARKER = "__netcatty_csv_localshell_v1__:";
 
 const encodeMarkedField = (value: string, marker: string): string => (
   FORMULA_PREFIX.test(value) || value.startsWith(marker)
@@ -41,3 +42,48 @@ export const encodeCsvProxy = (value: string): string => (
 export const decodeCsvProxy = (value: string): string => (
   decodeMarkedField(value, PROXY_MARKER)
 );
+
+export interface CsvLocalShellSpec {
+  shell?: string;
+  shellArgs?: string[];
+  shellName?: string;
+  shellIcon?: string;
+  startDir?: string;
+  /** Host OS of the local-shell entry; decides the default-shell fallback on connect. */
+  os?: "linux" | "windows" | "macos";
+}
+
+export const encodeCsvLocalShell = (spec: CsvLocalShellSpec): string => (
+  encodeMarkedField(JSON.stringify(spec), LOCAL_SHELL_MARKER)
+);
+
+const isNonEmptyString = (value: unknown): value is string => (
+  typeof value === "string" && value.trim().length > 0
+);
+
+const isNonEmptyStringArray = (value: unknown): value is string[] => (
+  Array.isArray(value) && value.length > 0 && value.every(isNonEmptyString)
+);
+
+export const decodeCsvLocalShell = (value: string): CsvLocalShellSpec | null => {
+  const raw = decodeMarkedField(value, LOCAL_SHELL_MARKER).trim();
+  if (!raw) return null;
+  try {
+    const parsed: unknown = JSON.parse(raw);
+    if (typeof parsed !== "object" || parsed === null) return null;
+    const record = parsed as Record<string, unknown>;
+    const spec: CsvLocalShellSpec = {
+      ...(isNonEmptyString(record.shell) ? { shell: record.shell } : {}),
+      ...(isNonEmptyStringArray(record.shellArgs) ? { shellArgs: record.shellArgs } : {}),
+      ...(isNonEmptyString(record.shellName) ? { shellName: record.shellName } : {}),
+      ...(isNonEmptyString(record.shellIcon) ? { shellIcon: record.shellIcon } : {}),
+      ...(isNonEmptyString(record.startDir) ? { startDir: record.startDir } : {}),
+      ...(record.os === "linux" || record.os === "windows" || record.os === "macos"
+        ? { os: record.os }
+        : {}),
+    };
+    return Object.keys(spec).length > 0 ? spec : null;
+  } catch {
+    return null;
+  }
+};

domain/vaultImport/csvExport.test.ts

@@ -55,6 +55,32 @@ test("CSV round-trips local key authentication and its saved passphrase", () =>
   }]);
 });
 
+test("CSV import keeps distinct local-shell entries in the same group", () => {
+  const localShellHost = (id: string, label: string, shell: string, shellName: string): Host => ({
+    ...hostDefaults,
+    id,
+    label,
+    hostname: "localhost",
+    port: 22,
+    protocol: "local",
+    group: "Shells",
+    localShell: shell,
+    localShellName: shellName,
+  });
+
+  const cmd = localShellHost("local-cmd", "Command Prompt", "cmd.exe", "Command Prompt");
+  const powershell = localShellHost("local-ps", "PowerShell", "powershell.exe", "Windows PowerShell");
+  const { csv } = exportHostsToCsvWithStats([cmd, powershell]);
+
+  const imported = importVaultHostsFromText("csv", csv);
+  assert.equal(imported.stats.duplicates, 0);
+  assert.equal(imported.hosts.length, 2);
+  assert.deepEqual(
+    imported.hosts.map((h) => h.localShell).sort(),
+    ["cmd.exe", "powershell.exe"],
+  );
+});
+
 test("CSV round-trips a referenced Keychain file path and saved passphrase", () => {
   const host: Host = {
     ...hostDefaults,
@@ -425,3 +451,67 @@ test("CSV reports unreadable proxy passwords for exported hosts only", () => {
   assert.deepEqual(imported.hosts.map((host) => host.proxyConfig?.password), [undefined, undefined, "readable"]);
   assert.equal(exportHostsToCsvWithStats([]).unreadableProxyCredentialCount, 0);
 });
+
+test("CSV round-trips local-shell vault host settings", () => {
+  const localHost: Host = {
+    ...hostDefaults,
+    id: "local-cmd",
+    label: "CMD host",
+    hostname: "localhost",
+    username: "",
+    protocol: "local",
+    os: "windows",
+    tags: ["local"],
+    localShell: "cmd",
+    localShellArgs: ["/k", "echo hi"],
+    localShellName: "CMD",
+    localShellIcon: "cmd",
+    localStartDir: "C:\\Users\\dev",
+  };
+  const defaultLocalHost: Host = {
+    ...hostDefaults,
+    id: "local-default",
+    label: "Local shell",
+    hostname: "localhost",
+    username: "",
+    protocol: "local",
+    os: "windows",
+    tags: ["local"],
+    group: "Backups",
+  };
+
+  const { csv, exportedCount, skippedCount } = exportHostsToCsvWithStats([localHost, defaultLocalHost]);
+  assert.equal(exportedCount, 2);
+  assert.equal(skippedCount, 0);
+
+  const imported = importVaultHostsFromText("csv", csv);
+  assert.equal(imported.hosts.length, 2);
+  assert.equal(imported.issues.length, 0);
+
+  const roundTripped = imported.hosts[0];
+  assert.equal(roundTripped.protocol, "local");
+  assert.equal(roundTripped.os, "windows");
+  assert.equal(roundTripped.localShell, "cmd");
+  assert.deepEqual(roundTripped.localShellArgs, ["/k", "echo hi"]);
+  assert.equal(roundTripped.localShellName, "CMD");
+  assert.equal(roundTripped.localShellIcon, "cmd");
+  assert.equal(roundTripped.localStartDir, "C:\\Users\\dev");
+
+  const roundTrippedDefault = imported.hosts[1];
+  assert.equal(roundTrippedDefault.protocol, "local");
+  assert.equal(roundTrippedDefault.os, "windows");
+  assert.equal(roundTrippedDefault.localShell, undefined);
+  assert.equal(roundTrippedDefault.localStartDir, undefined);
+});
+
+test("CSV import warns and ignores a malformed LocalShell value", () => {
+  const csv = [
+    "Groups,Label,Tags,Notes,Hostname/IP,Protocol,Port,Username,Password,KeyPath,Passphrase,Proxy,LocalShell",
+    ',"Bad local shell",,,localhost,local,22,,,,,,"not json"',
+  ].join("\r\n");
+
+  const imported = importVaultHostsFromText("csv", csv);
+  assert.equal(imported.hosts.length, 1);
+  assert.equal(imported.hosts[0]?.localShell, undefined);
+  assert.ok(imported.issues.some((issue) => issue.message.includes("row 2") && issue.message.includes("LocalShell")));
+});

domain/vaultImport/csvExport.ts

@@ -2,7 +2,7 @@ import type { GroupConfig, Host, Identity, ProxyProfile } from '../models';
 import { applyGroupDefaults, resolveGroupDefaults } from '../groupConfig';
 import { isPluginHostProtocol } from '../pluginConnection';
 import { hasUnreadableProxyCredential, materializeHostProxyProfile, resolveProxyConfigAuth } from '../proxyProfiles';
-import { encodeCsvKeyPath, encodeCsvPassphrase, encodeCsvProxy } from './csvCredentialFields';
+import { CsvLocalShellSpec, encodeCsvKeyPath, encodeCsvLocalShell, encodeCsvPassphrase, encodeCsvProxy } from './csvCredentialFields';
 import { formatCsvProxy } from './csvProxy';
 
 const UTF8_BOM = "\uFEFF";
@@ -36,7 +36,7 @@ export const getVaultCsvTemplate = (
   opts: VaultCsvTemplateOptions = {},
 ): string => {
   const includeExampleRows = opts.includeExampleRows !== false;
-  const header = ["Groups", "Label", "Tags", "Notes", "Hostname/IP", "Protocol", "Port", "Username", "Password", "KeyPath", "Passphrase", "Proxy"];
+  const header = ["Groups", "Label", "Tags", "Notes", "Hostname/IP", "Protocol", "Port", "Username", "Password", "KeyPath", "Passphrase", "Proxy", "LocalShell"];
   const rows: string[][] = [header];
   if (includeExampleRows) {
     rows.push(["Project/Dev", "Web Server (dev)", "dev,web", "Dev web tier", "192.168.1.10", "ssh", "22", "root", "", "~/.ssh/id_ed25519", "", "socks5://127.0.0.1:1080"]);
@@ -53,8 +53,32 @@ export const getVaultCsvTemplate = (
   return rows.map((r) => r.map((c) => escapeCsv(c)).join(",")).join("\r\n") + "\r\n";
 };
 
+// The legacy CSV format has no per-host shell columns, so local-shell vault
+// hosts are serialized as one encoded "LocalShell" field; hosts with a
+// non-default shell are otherwise lost on reimport (backup data silently
+// changed). Default-shell Windows/macOS local hosts still export their OS:
+// reimport defaults to Linux, and the OS is part of the reimport dedupe key,
+// so a macOS default-shell entry without an OS field would be reimported as
+// (and collapse with) a Linux host. Linux default-shell hosts match the
+// reimport default and need no field.
+const getLocalShellSpec = (host: Host): CsvLocalShellSpec | null => (
+  host.protocol === "local"
+    && (host.localShell || host.localShellName || host.localShellIcon
+      || host.localStartDir || host.localShellArgs?.length
+      || host.os === "windows" || host.os === "macos")
+    ? {
+        shell: host.localShell || undefined,
+        shellArgs: host.localShellArgs?.length ? host.localShellArgs : undefined,
+        shellName: host.localShellName || undefined,
+        shellIcon: host.localShellIcon || undefined,
+        startDir: host.localStartDir || undefined,
+        os: host.os === "windows" || host.os === "macos" ? host.os : undefined,
+      }
+    : null
+);
+
 const exportHostsToCsv = (hosts: Host[], options: VaultCsvExportOptions) => {
-  const header = ["Groups", "Label", "Tags", "Notes", "Hostname/IP", "Protocol", "Port", "Username", "Password", "KeyPath", "Passphrase", "Proxy"];
+  const header = ["Groups", "Label", "Tags", "Notes", "Hostname/IP", "Protocol", "Port", "Username", "Password", "KeyPath", "Passphrase", "Proxy", "LocalShell"];
   const rows: string[][] = [header];
   let unreadableProxyCredentialCount = 0;
 
@@ -118,6 +142,7 @@ const exportHostsToCsv = (hosts: Host[], options: VaultCsvExportOptions) => {
     const proxyValue = proxyConfig
       ? formatCsvProxy(resolveProxyConfigAuth(proxyConfig, options.identities))
       : "";
+    const localShellSpec = getLocalShellSpec(host);
 
     rows.push([
       host.group ?? "",
@@ -132,6 +157,7 @@ const exportHostsToCsv = (hosts: Host[], options: VaultCsvExportOptions) => {
       encodeCsvKeyPath(keyPath),
       encodeCsvPassphrase(passphrase),
       encodeCsvProxy(proxyValue),
+      localShellSpec ? encodeCsvLocalShell(localShellSpec) : "",
     ]);
   }
 

electron/bridges/ai/liveShellProbe.cjs

@@ -6,7 +6,17 @@ const { buildBashHistoryCleanup, bashHistoryScratchNames } = require("./ptyExecH
 // short-lived sh in the interactive PTY, rather than the SSH login shell.
 function buildLiveShellProbe(marker) {
   const script = 'if test -r "/proc/$PPID/comm"; then IFS= read -r name < "/proc/$PPID/comm"; else name=$(ps -p "$PPID" -o comm= 2>/dev/null); fi; '
-    + `printf "${marker}_P:%s\\n" "$name"`;
+    + `printf "\\n${marker}_P:%s\\n" "$name"`;
+  // Keep the initial probe short before the active shell is known. Quoted
+  // multiline cleanup input can leave a configured zsh editor waiting for
+  // continuation input, so defer that Bash-only work until after the reply.
+  return ` true ${marker}; printf '\\n%s\\n' '${marker}_I'\n : '${marker}'; command sh -c '${script}' 2>/dev/null; printf '%s' '${marker}_Q'\n`;
+}
+
+// This is sent after the short probe, except for zsh/fish replies. Keep the
+// existing guarded cleanup and bounded physical lines for Bash's history and
+// canonical-input behavior, including renamed Bash executables.
+function buildLiveShellProbeCleanup(marker) {
   // command eval bypasses an eval customization; plain eval is the fallback
   // when command itself is shadowed. Never invoke a shadowed builtin after the
   // command path already succeeded. Both eval bodies remain Bash-guarded.
@@ -14,10 +24,7 @@ function buildLiveShellProbe(marker) {
   const { dispatcher } = bashHistoryScratchNames(marker);
   const clear = `[ -z "\${${dispatcher}-}" ]||$${dispatcher} unset ${dispatcher}`;
   const fallback = `[ "\${${dispatcher}-}" = command ]||{ ${cleanup}; };${clear}`;
-  // Start display suppression in the PTY before any continuation is read,
-  // independently of PS2 and echo mode. Keep every later physical line short.
-  return ` true ${marker}; printf '\\n%s\\n' '${marker}_I'\n : '${marker}'; command sh -c '${script}' 2>/dev/null; \\\n: '${marker}'; \\command eval '${cleanup}' 2>/dev/null || true; \\\n: '${marker}'; \\eval '${fallback}' 2>/dev/null || true; \\\n: '${marker}'; \\command eval '${clear}' 2>/dev/null || true; printf '%s' '${marker}_Q'\n`;
-
+  return ` : '${marker}'; \\command eval '${cleanup}' 2>/dev/null || true; \\\n: '${marker}'; \\eval '${fallback}' 2>/dev/null || true; \\\n: '${marker}'; \\command eval '${clear}' 2>/dev/null || true\n`;
 }
 
 // Interactive bash prints PS2 (`> ` by default) on backslash continuations.
@@ -35,11 +42,12 @@ function parseLiveShellProbe(output, marker) {
     if (!normalized.startsWith(`${marker}_P:`)) continue;
     const name = normalized.slice(marker.length + 3).trim().split("/").pop().replace(/^-/, "");
     return {
+      shellName: name,
       kind: name === "fish" ? "fish"
         : /^(?:ba|da|z|k|a)?sh$/.test(name) ? "posix" : null,
     };
   }
-  return { kind: null };
+  return { kind: null, shellName: "" };
 }
 
-module.exports = { buildLiveShellProbe, parseLiveShellProbe, normalizeLiveShellProbeLine };
+module.exports = { buildLiveShellProbe, buildLiveShellProbeCleanup, parseLiveShellProbe, normalizeLiveShellProbeLine };

electron/bridges/ai/liveShellProbe.test.cjs

@@ -1,7 +1,7 @@
 const test = require('node:test');
 const assert = require('node:assert/strict');
 const { EventEmitter } = require('node:events');
-const { buildLiveShellProbe, parseLiveShellProbe } = require('./liveShellProbe.cjs');
+const { buildLiveShellProbe, buildLiveShellProbeCleanup, parseLiveShellProbe } = require('./liveShellProbe.cjs');
 const { startPtyJob } = require('./ptyExec.cjs');
 
 test('live shell response excludes echoed commands, stale markers and partial lines', () => {
@@ -9,11 +9,11 @@ test('live shell response excludes echoed commands, stale markers and partial li
   assert.equal(parseLiveShellProbe(buildLiveShellProbe(marker), marker), null);
   assert.equal(parseLiveShellProbe(`${marker}_P:fi`, marker), null);
   assert.equal(parseLiveShellProbe('__NCMCP_old___P:fish\n', marker), null);
-  assert.deepEqual(parseLiveShellProbe(`\r${marker}_P:/usr/bin/fish\r\n${marker}_Q`, marker), { kind: 'fish' });
-  assert.deepEqual(parseLiveShellProbe(`${marker}_P:-zsh\n${marker}_Q`, marker), { kind: 'posix' });
-  assert.deepEqual(parseLiveShellProbe(`${marker}_P:\n${marker}_Q`, marker), { kind: null });
-  assert.deepEqual(parseLiveShellProbe(`> ${marker}_P:bash\n> ${marker}_Q`, marker), { kind: 'posix' });
-  assert.deepEqual(parseLiveShellProbe(`> ${marker}_P:fish\n> ${marker}_Q`, marker), { kind: 'fish' });
+  assert.deepEqual(parseLiveShellProbe(`\r${marker}_P:/usr/bin/fish\r\n${marker}_Q`, marker), { kind: 'fish', shellName: 'fish' });
+  assert.deepEqual(parseLiveShellProbe(`${marker}_P:-zsh\n${marker}_Q`, marker), { kind: 'posix', shellName: 'zsh' });
+  assert.deepEqual(parseLiveShellProbe(`${marker}_P:\n${marker}_Q`, marker), { kind: null, shellName: '' });
+  assert.deepEqual(parseLiveShellProbe(`> ${marker}_P:bash\n> ${marker}_Q`, marker), { kind: 'posix', shellName: 'bash' });
+  assert.deepEqual(parseLiveShellProbe(`> ${marker}_P:fish\n> ${marker}_Q`, marker), { kind: 'fish', shellName: 'fish' });
 });
 
 test('probe waits for complete reply before choosing the first wrapper', async () => {
@@ -260,7 +260,7 @@ for (const [customization, listHistory] of [
       const { buildWrappedCommand } = require('./ptyExecHelpers.cjs');
       const marker = '__NCMCP_HISTORY_PROBE__';
       const input = `HISTFILE=/dev/null; HISTCONTROL=; PS1=; PS2=\n${customization}\n${listHistory} -c\necho user_one\necho user_two\n`
-        + buildLiveShellProbe(marker)
+        + buildLiveShellProbe(marker) + buildLiveShellProbeCleanup(marker)
         + (executeCommand ? buildWrappedCommand('echo command_ok', 'posix', marker, true) : '')
         + '\nprintf \"\\n\"\n' + listHistory + '\nexit\n';
       const result = spawnSync('/bin/bash', ['--noprofile', '--norc', '-i'], {
@@ -337,7 +337,7 @@ for (const invocationName of ['sh', 'renamed-bash']) {
       const marker = '__NCMCP_RENAMED_BASH__';
       const result = spawnSync(shell, ['--noprofile', '--norc', '-i'], {
         input: 'HISTFILE=/dev/null; HISTCONTROL=; PS1=; PS2=\nbuiltin history -c\necho preserve_user_history\n'
-          + buildLiveShellProbe(marker) + '\nprintf "\\n"\ncommand builtin history\nexit\n',
+          + buildLiveShellProbe(marker) + buildLiveShellProbeCleanup(marker) + '\nprintf "\\n"\ncommand builtin history\nexit\n',
         encoding: 'utf8', env: { ...process.env, TERM: 'dumb' }, timeout: 5000,
       });
       assert.equal(result.status, 0, result.stderr);
@@ -389,7 +389,7 @@ for (const historyControl of ['', 'ignorespace']) {
     const { buildWrappedCommand } = require('./ptyExecHelpers.cjs');
     const marker = '__NCMCP_FALLBACK_GUARD__';
     const input = `HISTFILE=/dev/null; HISTCONTROL=${historyControl}; PS1=; PS2=\nbuiltin() { printf UNEXPECTED_FALLBACK; }\ncommand history -c\necho user_one\n`
-      + buildLiveShellProbe(marker)
+      + buildLiveShellProbe(marker) + buildLiveShellProbeCleanup(marker)
       + buildWrappedCommand('echo command_ok', 'posix', marker, true)
       + '\ncommand history\nexit\n';
     const result = spawnSync('/bin/bash', ['--noprofile', '--norc', '-i'], {
@@ -406,7 +406,7 @@ for (const historyControl of ['', 'ignorespace']) {
 }
 
 for (const stop of ['cancel', 'timeout']) {
-  test(`paced probe stops writing after ${stop}`, async () => {
+  test(`paced Bash probe cleanup stops writing after ${stop}`, async () => {
     const pty = new EventEmitter();
     const writes = [];
     pty.write = data => writes.push(data);
@@ -414,8 +414,9 @@ for (const stop of ['cancel', 'timeout']) {
       shellKind: 'posix', probeLiveShell: true, timeoutMs: stop === 'timeout' ? 70 : 1000,
       enforceWallTimeout: stop === 'timeout',
     });
+    pty.emit('data', `${job.marker}_P:bash\n${job.marker}_Q`);
     await new Promise(resolve => setTimeout(resolve, 45));
-    assert.ok(writes.length >= 2, 'probe must have started a later chunk');
+    assert.ok(writes.length >= 3, 'cleanup must have started a later chunk');
     if (stop === 'cancel') {
       job.cancel();
       pty.emit('close');
@@ -427,3 +428,19 @@ for (const stop of ['cancel', 'timeout']) {
     assert.ok(writes.every(data => !data.includes('must_not_run')));
   });
 }
+
+for (const shellName of ['zsh', '/bin/zsh', 'zsh-5.9', 'fish', 'bash', 'sh', 'renamed-bash']) {
+  test(`live probe defers Bash history input until shell reply (${shellName})`, async () => {
+    const pty = new EventEmitter();
+    const writes = [];
+    pty.write = (data) => writes.push(String(data));
+    const job = startPtyJob(pty, 'printf success', { shellKind: 'posix', probeLiveShell: true, timeoutMs: 1000 });
+    assert.doesNotMatch(writes.join(''), /history -d|printf success/);
+    pty.emit('data', `${job.marker}_P:${shellName}\n${job.marker}_Q`);
+    const deferred = writes.slice(1).join('');
+    const needsCleanup = shellName !== 'fish' && !/zsh/.test(shellName);
+    assert.equal(deferred.includes('\\command eval'), needsCleanup);
+    pty.emit('data', `${job.marker}_S\nsuccess\n${job.marker}_E:0\n`);
+    assert.equal((await job.resultPromise).exitCode, 0);
+  });
+}

electron/bridges/ai/ptyExec.cjs

@@ -28,7 +28,7 @@ const {
 } = require("./ptyExecHelpers.cjs");
 const { extractTrailingIdlePrompt } = require("./shellUtils.cjs");
 
-const { buildLiveShellProbe, parseLiveShellProbe } = require("./liveShellProbe.cjs");
+const { buildLiveShellProbe, buildLiveShellProbeCleanup, parseLiveShellProbe } = require("./liveShellProbe.cjs");
 
 const DEFAULT_FOREGROUND_PTY_CAPTURE_CHARS = 1024 * 1024;
 const END_MARKER_PROMPT_WAIT_MS = 30000;
@@ -560,7 +560,9 @@ function startPtyJob(ptyStream, command, options) {
       probeOutput = "";
       if (probe.kind) resolvedShellKind = probe.kind;
       if (finished || cancelRequested) return;
-      writeWrappedCommand();
+      const isZsh = /^zsh(?:[-.][0-9].*)?$/i.test(probe.shellName);
+      const skipProbeCleanup = probe.kind === "fish" || isZsh;
+      writeWrappedCommand(skipProbeCleanup ? "" : buildLiveShellProbeCleanup(marker), isZsh);
       return;
     }
 
@@ -822,9 +824,14 @@ function startPtyJob(ptyStream, command, options) {
     writeNext();
   }
 
-  function writeWrappedCommand() {
-    const wrapped = buildWrappedCommand(command, resolvedShellKind, marker, probeLiveShell);
-    writeInput(`${(skipPendingInputClear ? "" : buildPendingInputClearPrefix(resolvedShellKind))}${wrapped}`);
+  function writeWrappedCommand(probeCleanup = "", isZsh = false) {
+    // The Bash-only cleanup is a no-op in zsh, but its long input still goes
+    // through the configured editor. Keep the existing bounded wrapper and
+    // omit only that unused fragment after a live zsh reply.
+    const wrapped = buildWrappedCommand(command, resolvedShellKind, marker, probeLiveShell, {
+      omitBashHistoryCleanup: isZsh,
+    });
+    writeInput(`${(skipPendingInputClear ? "" : buildPendingInputClearPrefix(resolvedShellKind))}${probeCleanup}${wrapped}`);
   }
 
   // Prime the renderer's display suppression before the first byte is typed

electron/bridges/ai/ptyExecHelpers.cjs

@@ -243,7 +243,7 @@ function buildBashHistoryCleanup(marker, keepDispatcher = false) {
   ].join(` \\\n: "${marker}"; `);
 }
 
-function buildPosixWrapperBody(command, marker, startFormat) {
+function buildPosixWrapperBody(command, marker, startFormat, { omitBashHistoryCleanup = false } = {}) {
   const noPager = "PAGER=cat SYSTEMD_PAGER= GIT_PAGER=cat LESS= ";
   const commandLines = String(command || "").replace(/\r\n?/g, "\n").split("\n");
   let cmdAssign = commandLines.length > 1
@@ -273,7 +273,7 @@ function buildPosixWrapperBody(command, marker, startFormat) {
     }
     cmdAssign = `${marker}_cmd=$(${writes.join(`; \\\n: '${marker}'; `)})`;
   }
-  const historyCleanup = buildBashHistoryCleanup(marker);
+  const historyCleanup = omitBashHistoryCleanup ? [] : [buildBashHistoryCleanup(marker)];
   // OpenWrt builds BusyBox with a 512-byte interactive line editor. Keep
   // every physical line below that limit, even for short user commands.
   // Emit a short standalone input marker before the shell reads any PS2
@@ -282,12 +282,12 @@ function buildPosixWrapperBody(command, marker, startFormat) {
     ` : '${marker}'; ${cmdAssign}`,
     `{ printf '${startFormat}' '${marker}_S'; trap ':' INT; ( ${noPager}eval "$${marker}_cmd" ); __NCMCP_rc=$?; trap - INT`,
     `printf '%s\\n' '${marker}_E:'"$__NCMCP_rc"`,
-    historyCleanup,
+    ...historyCleanup,
     `(exit $__NCMCP_rc); }`,
   ].join(`; \\\n: '${marker}'; `);
 }
 
-function buildWrappedCommand(command, shellKind, marker, separateStartMarker = false) {
+function buildWrappedCommand(command, shellKind, marker, separateStartMarker = false, options = {}) {
   // A live probe leaves its completion marker unterminated to hide the next
   // prompt. POSIX input also hides arbitrary PS2 prompts until a fresh start
   // marker line; keep the fish behavior controlled by separateStartMarker.
@@ -366,7 +366,7 @@ function buildWrappedCommand(command, shellKind, marker, separateStartMarker = f
       // can opt in by adding `HISTCONTROL=ignoreboth` to ~/.bashrc.
       // Without that config the prefix is harmless; it just doesn't
       // suppress history recording.
-      return ` ${buildPosixWrapperBody(command, marker, "\\n%s\\n")}\n`;
+      return ` ${buildPosixWrapperBody(command, marker, "\\n%s\\n", options)}\n`;
     }
   }
 }

electron/bridges/ai/shellUtils.cjs

@@ -13,7 +13,7 @@ const path = require("node:path");
 // ── ANSI / URL regexes ──
 
 const ANSI_ESCAPE_REGEX = /\u001B\[[0-?]*[ -/]*[@-~]/g;
-const ANSI_OSC_REGEX = /\u001B\][^\u0007]*(?:\u0007|\u001B\\)/g;
+const ANSI_OSC_REGEX = /\u001B\][^\u0007]*?(?:\u0007|\u001B\\)/g;
 const URL_CANDIDATE_REGEX = /https?:\/\/[^\s]+/g;
 const WINDOWS_RUNNABLE_EXTENSIONS = [".exe", ".cmd", ".bat", ".com"];
 const MAX_PROMPT_TRACK_TAIL = 4096;

electron/bridges/ai/shellUtils.test.cjs

@@ -2,6 +2,7 @@ const test = require("node:test");
 const assert = require("node:assert/strict");
 
 const {
+  stripAnsi,
   addCodexExecutableEnvForSdk,
   buildWindowsShellCommandLine,
   extractTrailingIdlePrompt,
@@ -28,6 +29,19 @@ const fs = require("node:fs");
 const os = require("node:os");
 const path = require("node:path");
 
+test("OSC stripping preserves text between independently terminated sequences", () => {
+  for (const firstEnd of ["\x07", "\x1b\\"]) {
+    for (const secondEnd of ["\x07", "\x1b\\"]) {
+      const text = `\x1b]3008;start${firstEnd}\nprobe-reply\n\x1b]3008;end${secondEnd}prompt`;
+      assert.equal(stripAnsi(text), "\nprobe-reply\nprompt");
+    }
+  }
+  assert.equal(
+    stripAnsi("before\x1b[31mcolored\x1b[0m\x1b]0;title\x07after"),
+    "beforecoloredafter",
+  );
+});
+
 test("formatSyntheticEcho normalizes multi-line commands to CRLF so xterm doesn't staircase", () => {
   assert.equal(
     formatSyntheticEcho("set -e\ncd /tmp\necho done"),

electron/bridges/localFilePublish.cjs

@@ -8,24 +8,27 @@ const fs = require("node:fs");
 // but no pathname cleanup may remove a concurrent writer's replacement.
 // Resolves with the published inode identity ({ dev, ino, size }) so callers can
 // verify an open destination handle before later metadata stamping.
-async function publishLocalFileExclusive(source, target, assertNotCancelled = () => {}, preparedHandle) {
+async function publishLocalFileExclusive(source, target, assertNotCancelled = () => {}, preparedHandle, options = {}) {
   assertNotCancelled();
-  try {
-    await fs.promises.link(source, target);
-    // The hardlink shares the published inode; stat either name.
-    const linkedStat = await fs.promises.lstat(source);
-    return { dev: linkedStat.dev, ino: linkedStat.ino, size: linkedStat.size };
-  } catch (error) {
-    // EISDIR is the misleading libuv mapping for Win32 ERROR_INVALID_FUNCTION
-    // when the volume has no hard-link support (exFAT/FAT32); the source here
-    // is always a regular prepared file, never a directory (nodejs/node#65817).
-    if (!["ENOTSUP", "EOPNOTSUPP", "ENOSYS", "EPERM", "EACCES", "EXDEV", "EISDIR"].includes(error?.code)) throw error;
+  if (!options.copyOnly) {
+    try {
+      await fs.promises.link(source, target);
+      // The hardlink shares the published inode; stat either name.
+      const linkedStat = await fs.promises.lstat(source);
+      return { dev: linkedStat.dev, ino: linkedStat.ino, size: linkedStat.size };
+    } catch (error) {
+      // EISDIR is the misleading libuv mapping for Win32 ERROR_INVALID_FUNCTION
+      // when the volume has no hard-link support (exFAT/FAT32); the source here
+      // is always a regular prepared file, never a directory (nodejs/node#65817).
+      if (!["ENOTSUP", "EOPNOTSUPP", "ENOSYS", "EPERM", "EACCES", "EXDEV", "EISDIR"].includes(error?.code)) throw error;
+    }
   }
 
   let input;
   let output;
   let failure;
   let publishedIdentity;
+  let timestampsPreserved = true;
   try {
     input = preparedHandle ?? await fs.promises.open(source, "r");
     const stat = await input.stat();
@@ -49,14 +52,31 @@ async function publishLocalFileExclusive(source, target, assertNotCancelled = ()
     assertNotCancelled();
     // Restore metadata after writes (which may clear special permission bits),
     // through the owned handle rather than a potentially replaced pathname.
-    await output.chmod(stat.mode & 0o7777);
-    await output.utimes(stat.atime, stat.mtime);
+    const mode = stat.mode & 0o7777;
+    if (((await output.stat()).mode & 0o7777) !== mode) {
+      try {
+        await output.chmod(mode);
+      } catch (error) {
+        // New files follow the mount's access policy (GVFS can synthesize mode
+        // bits). Replacements must still preserve the validated protection.
+        if (!isOptionalMetadataError(error) || options.preserveMode !== false) throw error;
+      }
+      if (options.preserveMode !== false && ((await output.stat()).mode & 0o7777) !== mode) {
+        throw new Error("Cannot preserve local destination permissions");
+      }
+    }
+    try {
+      await output.utimes(stat.atime, stat.mtime);
+    } catch (error) {
+      if (!isOptionalMetadataError(error) || options.requireTimestamps !== false) throw error;
+      timestampsPreserved = false;
+    }
     const ownedStat = await output.stat();
     const targetStat = await fs.promises.lstat(target);
     if (!targetStat.isFile() || targetStat.dev !== ownedStat.dev || targetStat.ino !== ownedStat.ino) {
       throw new Error("Local download target changed during replacement");
     }
-    publishedIdentity = { dev: ownedStat.dev, ino: ownedStat.ino, size: ownedStat.size };
+    publishedIdentity = { dev: ownedStat.dev, ino: ownedStat.ino, size: ownedStat.size, timestampsPreserved };
   } catch (error) {
     failure = error;
   } finally {
@@ -73,4 +93,14 @@ async function publishLocalFileExclusive(source, target, assertNotCancelled = ()
   return publishedIdentity;
 }
 
-module.exports = { publishLocalFileExclusive };
+// Only optional chmod/utimes may ignore permission refusal. Never use this
+// predicate for creation, data writes, close, or required permission changes.
+function isOptionalMetadataError(error) {
+  return isMetadataUnsupportedError(error) || ["EPERM", "EACCES"].includes(error?.code);
+}
+
+function isMetadataUnsupportedError(error) {
+  return ["ENOTSUP", "EOPNOTSUPP", "ENOSYS"].includes(error?.code);
+}
+
+module.exports = { publishLocalFileExclusive, isMetadataUnsupportedError };

electron/bridges/mcpServerBridge.cjs

@@ -727,6 +727,15 @@ function syncLiveSessionsToExternalScope(chatSessionId = EXTERNAL_MCP_CHAT_SESSI
     }
     return { ok: true, count: 0, chatSessionId };
   }
+  // A reconnecting renderer tab can be absent from the backend map while
+  // another terminal is still live. Preserve its already scoped metadata;
+  // authoritative renderer updates remove it when the tab actually closes.
+  const liveIds = new Set(sessionList.map((entry) => entry.sessionId));
+  for (const [sessionId, meta] of existingMeta) {
+    if (!liveIds.has(sessionId) && meta.connected === false) {
+      sessionList.push({ sessionId, ...meta });
+    }
+  }
   updateSessionMetadata(sessionList, chatSessionId);
   return { ok: true, count: sessionList.length, chatSessionId };
 }
@@ -1615,6 +1624,17 @@ const dispatchCapabilityRpc = createCapabilityRpcDispatcher({
     // explicitly closes it while that reply is still in flight, the eventual
     // result must not revive ownership or scope metadata for the closed tab.
     if ((closedTerminalSessionRevisions.get(sessionId) || 0) > generation?.closeRevision) return;
+    // Reuse adds visibility only: never grant ownership or change the original
+    // owner's idle lifecycle merely because another chat referenced the tab.
+    if (result?.reused === true) {
+      if (generation?.ownershipGeneration?.revoked) {
+        // A late renderer merge must not recreate a deleted chat's scope.
+        scopedMetadata.delete(chatSessionId);
+        return;
+      }
+      ensureOpenedSessionMetadata(chatSessionId, sessionId, result);
+      return;
+    }
     if (!openedSessionOwnership.register(
       chatSessionId,
       sessionId,
@@ -2232,10 +2252,16 @@ async function handleGetContext(params) {
     const hasCommandablePty = ptyStream && typeof ptyStream.write === "function";
     const hasSshExec = sshClient && typeof sshClient.exec === "function";
     const hasSerialPort = session.serialPort && typeof session.serialPort.write === "function";
-    if (!hasCommandablePty && !hasSshExec && !hasSerialPort) continue;
-
-    // Look up metadata scoped to this chat session
-    const meta = getSessionMeta(sessionId, chatSessionId) || {};
+    const hasTransport = hasCommandablePty || hasSshExec || hasSerialPort;
+    // Look up metadata scoped to this chat session.
+    const scopeMeta = getSessionMeta(sessionId, chatSessionId);
+    // Disconnected/reconnecting tabs keep their session entry (SSH
+    // auto-reconnect reuses the sessionId), so keep them visible with
+    // connected:false instead of hiding them — otherwise the agent cannot
+    // see or wait for a tab it opened and reopens it as a duplicate.
+    // Without scoped metadata the session is not in this agent's scope.
+    if (!hasTransport && !scopeMeta) continue;
+    const meta = scopeMeta || {};
     hosts.push({
       sessionId,
       hostname: meta.hostname || session.hostname || "",
@@ -2245,7 +2271,7 @@ async function handleGetContext(params) {
       protocol: meta.protocol || session.protocol || session.type || "",
       shellType: meta.shellType || session.shellKind || "",
       deviceType: meta.deviceType || "",
-      connected: meta.connected !== undefined ? meta.connected : !!(session.sshClient || session.conn || ptyStream || session.serialPort),
+      connected: meta.connected !== undefined ? meta.connected : hasTransport,
       hostId: meta.hostId || "",
       hostChain: meta.hostChain || [],
       activePortForwards: meta.activePortForwards || [],
@@ -2257,7 +2283,10 @@ async function handleGetContext(params) {
     for (const sessionId of resolvedScopedIds) {
       if (addedHostIds.has(sessionId)) continue;
       const meta = getSessionMeta(sessionId, chatSessionId);
-      if (!meta || meta.connected === false) continue;
+      if (!meta) continue;
+      // Keep disconnected/reconnecting sessions listed with connected:false so
+      // the agent can wait on the existing sessionId instead of reopening the
+      // host as a duplicate tab (SSH auto-reconnect preserves the sessionId).
       hosts.push(buildHostFromMetadata(sessionId, meta));
       addedHostIds.add(sessionId);
     }
@@ -2278,6 +2307,7 @@ async function handleGetContext(params) {
       "Use the provided tools to execute commands through the sessions exposed by Netcatty. " +
       buildTerminalToolGuidance(toolHints) +
       "Serial sessions (protocol: serial, shellType: raw) do not run a standard shell — commands are sent as-is. " +
+      "A session listed with connected false is still in the scope. SSH auto-reconnect keeps the same sessionId: wait and retry that session while it reconnects. Inactive disconnected or restored tabs may require user action; host_open reuses connected or connecting sessions by default and opens a connection when none is usable. " +
       "Network device sessions (deviceType: network) use vendor CLIs (Huawei VRP, Cisco IOS, etc.) — commands are sent as-is without shell wrapping, and exit codes are unavailable. " +
       "Vault snippets, port forwarding rules/tunnels, and SFTP read/write tools are available when exposed in the tool list. " +
       "Always prefer these tools over suggesting the user to do things manually.",

electron/bridges/mcpServerBridge.reconnectingSession.test.cjs

@@ -0,0 +1,162 @@
+"use strict";
+
+const assert = require("node:assert/strict");
+const test = require("node:test");
+
+const { isolateCliDiscoveryFile } = require("./cliDiscoveryTestIsolation.cjs");
+isolateCliDiscoveryFile();
+
+function loadFreshBridge() {
+  const bridgePath = require.resolve("./mcpServerBridge.cjs");
+  delete require.cache[bridgePath];
+  return require("./mcpServerBridge.cjs");
+}
+
+function setup(t, { sessions } = {}) {
+  const bridge = loadFreshBridge();
+  t.after(() => bridge.cleanup());
+  bridge.init({ sessions: sessions || new Map(), electronModule: null });
+  bridge.setPermissionMode("auto");
+  return bridge;
+}
+
+test('reusing a user tab adds visibility without ownership or idle tracking', async (t) => {
+  const bridge = setup(t);
+  bridge.setVaultAgentInvoker(async () => ({ ok: true, reused: true, sessionId: 'user-tab', hostId: 'host-b', status: 'connected' }));
+  await bridge.dispatchBuiltinRpc('public/vault/hosts/open', { chatSessionId: 'chat-b', hostId: 'host-b' });
+  assert.deepEqual(bridge.getScopedSessionIds('chat-b'), ['user-tab']);
+  assert.equal(bridge.reportOpenedSessionActivity({ sessionId: 'user-tab', phase: 'touch' }), false);
+  const close = await bridge.dispatchBuiltinRpc('public/session/close', { chatSessionId: 'chat-b', sessionId: 'user-tab' });
+  assert.equal(close.ok, false);
+  assert.match(close.error, /not opened by the current AI scope/);
+});
+
+test('reuse keeps the original chat owner and its idle tracking', async (t) => {
+  const bridge = setup(t);
+  const calls = [];
+  bridge.setVaultAgentInvoker(async (op, params) => {
+    calls.push({ op, params });
+    if (op === 'session.close') return { ok: true };
+    return { ok: true, reused: params.chatSessionId !== 'owner', sessionId: 'shared-tab', hostId: 'host-b', status: 'connected' };
+  });
+  for (const chatSessionId of ['owner', 'borrower']) {
+    await bridge.dispatchBuiltinRpc('public/vault/hosts/open', { chatSessionId, hostId: 'host-b' });
+  }
+  assert.equal(bridge.reportOpenedSessionActivity({ sessionId: 'shared-tab', phase: 'touch' }), true);
+  assert.equal((await bridge.dispatchBuiltinRpc('public/session/close', { chatSessionId: 'borrower', sessionId: 'shared-tab' })).ok, false);
+  assert.equal((await bridge.dispatchBuiltinRpc('public/session/close', { chatSessionId: 'owner', sessionId: 'shared-tab' })).ok, true);
+  assert.equal(calls.filter(({ op }) => op === 'session.close').length, 1);
+});
+
+test('a deleted chat cannot reclaim a reused tab or revive its own scope', async (t) => {
+  const bridge = setup(t);
+  let finishOpen;
+  const calls = [];
+  bridge.updateSessionMetadata([{ sessionId: 'user-tab', connected: true }], 'original');
+  bridge.setVaultAgentInvoker((op) => {
+    calls.push(op);
+    return new Promise((resolve) => { finishOpen = resolve; });
+  });
+  const opening = bridge.dispatchBuiltinRpc('public/vault/hosts/open', { chatSessionId: 'deleted', hostId: 'host-b' });
+  await bridge.cleanupScopedMetadata('deleted');
+  bridge.mergeSessionMetadata([{ sessionId: 'user-tab', connected: true }], 'deleted');
+  finishOpen({ ok: true, reused: true, sessionId: 'user-tab', status: 'connected' });
+  assert.equal((await opening).ok, true);
+  assert.deepEqual(calls, ['host.open']);
+  assert.deepEqual(bridge.getScopedSessionIds('deleted'), []);
+  assert.deepEqual(bridge.getScopedSessionIds('original'), ['user-tab']);
+  assert.equal(bridge.reportOpenedSessionActivity({ sessionId: 'user-tab', phase: 'touch' }), false);
+});
+
+test("getContext keeps a scoped disconnected session visible with connected:false", async (t) => {
+  const bridge = setup(t);
+  bridge.updateSessionMetadata([
+    {
+      sessionId: "sess-reconnecting",
+      hostname: "10.0.0.2",
+      label: "server-b",
+      connected: true,
+      hostId: "host-b",
+      protocol: "ssh",
+    },
+  ], "chat-1");
+  // Connection dropped: renderer pushes connected:false while the tab
+  // auto-reconnects. The scope keeps the same sessionId.
+  bridge.updateSessionMetadata([
+    {
+      sessionId: "sess-reconnecting",
+      hostname: "10.0.0.2",
+      label: "server-b",
+      connected: false,
+      hostId: "host-b",
+      protocol: "ssh",
+    },
+  ], "chat-1");
+
+  const environment = await bridge.dispatchBuiltinRpc("netcatty/getContext", {
+    chatSessionId: "chat-1",
+  });
+  const host = environment.hosts.find((entry) => entry.sessionId === "sess-reconnecting");
+  assert.ok(host, "reconnecting session must stay visible to the agent");
+  assert.equal(host.connected, false);
+});
+
+test("getContext keeps a live-map session without transport visible when scoped", async (t) => {
+  const bridge = setup(t, {
+    sessions: new Map([["sess-live", { hostname: "10.0.0.3", label: "server-c" }]]),
+  });
+  bridge.updateSessionMetadata([
+    {
+      sessionId: "sess-live",
+      hostname: "10.0.0.3",
+      label: "server-c",
+      connected: false,
+      hostId: "host-c",
+      protocol: "ssh",
+    },
+  ], "chat-1");
+
+  const environment = await bridge.dispatchBuiltinRpc("netcatty/getContext", {
+    chatSessionId: "chat-1",
+  });
+  const host = environment.hosts.find((entry) => entry.sessionId === "sess-live");
+  assert.ok(host, "reconnecting live-map session must stay visible");
+  assert.equal(host.connected, false);
+});
+
+test("getContext still hides disconnected sessions outside the agent scope", async (t) => {
+  const bridge = setup(t);
+  bridge.updateSessionMetadata([
+    {
+      sessionId: "foreign",
+      hostname: "10.0.0.9",
+      label: "foreign",
+      connected: false,
+      hostId: "host-x",
+      protocol: "ssh",
+    },
+  ], "chat-other");
+
+  const environment = await bridge.dispatchBuiltinRpc("netcatty/getContext", {
+    chatSessionId: "chat-1",
+  });
+  assert.equal(environment.hosts.length, 0);
+});
+
+test("external context preserves reconnecting metadata beside another live transport", async (t) => {
+  const bridge = setup(t, { sessions: new Map([["online", { hostname: "online", stream: { write() {} } }]]) });
+  const scope = bridge.EXTERNAL_MCP_CHAT_SESSION_ID;
+  bridge.setExternalMcpHooks({ isEnabled: () => true });
+  bridge.updateSessionMetadata([
+    { sessionId: "online", hostname: "online", connected: true },
+    { sessionId: "retrying", hostname: "retrying", connected: false },
+  ], scope);
+  const context = await bridge.dispatchBuiltinRpc("netcatty/getContext", { chatSessionId: scope });
+  assert.equal(context.hostCount, 2);
+  assert.equal(context.hosts.find(host => host.sessionId === "retrying")?.connected, false);
+  assert.equal(context.hosts.find(host => host.sessionId === "online")?.connected, true);
+  // A renderer-authoritative removal must still remove the closed tab.
+  bridge.updateSessionMetadata([{ sessionId: "online", connected: true }], scope);
+  const afterClose = await bridge.dispatchBuiltinRpc("netcatty/getContext", { chatSessionId: scope });
+  assert.deepEqual(afterClose.hosts.map(host => host.sessionId), ["online"]);
+});

electron/bridges/sftpBridge/scpAiTransferAbort.test.cjs

@@ -560,6 +560,54 @@ describe("AI/MCP SCP transfer abort on shipped download/upload entry points", ()
     assert.deepEqual(leftovers, []);
   });
 
+  it("downloadSftpToLocal cancels and clears the stage before fallback creates output", async (t) => {
+    const controller = new AbortController();
+    const payload = Buffer.from("complete-download-before-cancel");
+    const localPath = path.join(tmpDir, "cancel-before-fallback.bin");
+    fs.writeFileSync(localPath, "original");
+    let stagedPath;
+    t.after(() => { if (stagedPath) fs.rmSync(stagedPath, { force: true }); });
+    const events = [];
+    sftpClients.set("scp-pre-fallback-cancel", {
+      __netcattyFileProtocol: "scp",
+      __netcattyScpBackend: {
+        async stat() { return { type: "file", isDirectory: false, size: payload.length }; },
+        async downloadFile(_remotePath, stage) {
+          stagedPath = stage;
+          await fs.promises.writeFile(stage, payload);
+          return { fileSize: payload.length, transferred: payload.length };
+        },
+      },
+    });
+    for (const name of ["rename", "copyFile"]) {
+      const original = fs.promises[name];
+      t.after(() => { fs.promises[name] = original; });
+      fs.promises[name] = async (...args) => {
+        if (args[0] === stagedPath && String(args[1]).endsWith(".ready")) {
+          if (name === "copyFile") controller.abort();
+          throw Object.assign(new Error("injected cross-device copy refusal"), {
+            code: name === "rename" ? "EXDEV" : "ENOTSUP",
+          });
+        }
+        return original.apply(fs.promises, args);
+      };
+    }
+    await assert.rejects(() => sftpBridge.downloadSftpToLocal(null, {
+      sftpId: "scp-pre-fallback-cancel", remotePath: "/remote/file.bin", localPath,
+      abortSignal: controller.signal,
+      onTransferEvent: (channel) => events.push(channel),
+    }), (error) => {
+      assert.match(error.message, /cancel|abort/i);
+      assert.doesNotMatch(error.message, /Recovery files preserved/);
+      return true;
+    });
+    assert.ok(stagedPath);
+    assert.equal(fs.existsSync(stagedPath), false);
+    assert.equal(fs.readFileSync(localPath, "utf8"), "original");
+    assert.ok(events.includes("netcatty:transfer:cancelled"));
+    assert.equal(events.includes("netcatty:transfer:error"), false);
+  });
+
   it("downloadSftpToLocal leaves the original untouched when mode setup fails", {
     skip: process.platform === "win32",
   }, async (t) => {
@@ -582,16 +630,11 @@ describe("AI/MCP SCP transfer abort on shipped download/upload entry points", ()
     await fs.promises.writeFile(localPath, original, { mode: 0o600 });
     await fs.promises.chmod(localPath, 0o600);
 
-    const originalChmod = fs.promises.chmod;
-    fs.promises.chmod = async (filePath, mode) => {
-      if (String(filePath).includes(".netcatty-") && String(filePath).endsWith(".ready")) {
-        const error = new Error("injected chmod failure");
-        error.code = "EPERM";
-        throw error;
-      }
-      return originalChmod(filePath, mode);
-    };
-    t.after(() => { fs.promises.chmod = originalChmod; });
+    interceptPreparedChmod(t, async () => {
+      const error = new Error("injected chmod failure");
+      error.code = "EPERM";
+      throw error;
+    });
 
     await assert.rejects(
       () => sftpBridge.downloadSftpToLocal(null, {
@@ -630,18 +673,14 @@ describe("AI/MCP SCP transfer abort on shipped download/upload entry points", ()
     const original = Buffer.from("original-before-late-change");
     await fs.promises.writeFile(localPath, original, { mode: 0o600 });
 
-    const originalChmod = fs.promises.chmod;
     let releaseChmod;
     let markChmodStarted;
     const chmodStarted = new Promise((resolve) => { markChmodStarted = resolve; });
-    fs.promises.chmod = async (filePath, mode) => {
-      if (String(filePath).includes(".netcatty-") && String(filePath).endsWith(".ready")) {
-        markChmodStarted();
-        await new Promise((resolve) => { releaseChmod = resolve; });
-      }
-      return originalChmod(filePath, mode);
-    };
-    t.after(() => { fs.promises.chmod = originalChmod; });
+    interceptPreparedChmod(t, async (chmod, mode) => {
+      markChmodStarted();
+      await new Promise((resolve) => { releaseChmod = resolve; });
+      return chmod(mode);
+    });
 
     const running = sftpBridge.downloadSftpToLocal(null, {
       sftpId: "scp-late-directory",
@@ -685,18 +724,14 @@ describe("AI/MCP SCP transfer abort on shipped download/upload entry points", ()
     await fs.promises.writeFile(localPath, original, { mode: 0o600 });
     await fs.promises.chmod(localPath, 0o600);
 
-    const originalChmod = fs.promises.chmod;
     let releaseChmod;
     let markChmodStarted;
     const chmodStarted = new Promise((resolve) => { markChmodStarted = resolve; });
-    fs.promises.chmod = async (filePath, mode) => {
-      if (String(filePath).includes(".netcatty-") && String(filePath).endsWith(".ready")) {
-        markChmodStarted();
-        await new Promise((resolve) => { releaseChmod = resolve; });
-      }
-      return originalChmod(filePath, mode);
-    };
-    t.after(() => { fs.promises.chmod = originalChmod; });
+    interceptPreparedChmod(t, async (chmod, mode) => {
+      markChmodStarted();
+      await new Promise((resolve) => { releaseChmod = resolve; });
+      return chmod(mode);
+    });
 
     const running = sftpBridge.downloadSftpToLocal(null, {
       sftpId: "scp-same-mode-replacement",
@@ -986,3 +1021,17 @@ describe("AI/MCP SCP transfer abort on shipped download/upload entry points", ()
     assert.match(unifiedBlock, /transferBridge\.cancelTransfer/);
   });
 });
+
+
+function interceptPreparedChmod(t, callback) {
+  const originalOpen = fs.promises.open;
+  fs.promises.open = async (filePath, ...args) => {
+    const handle = await originalOpen.call(fs.promises, filePath, ...args);
+    if (String(filePath).includes(".netcatty-") && String(filePath).endsWith(".ready") && args[0] === "r") {
+      const chmod = handle.chmod.bind(handle);
+      handle.chmod = (mode) => callback(chmod, mode);
+    }
+    return handle;
+  };
+  t.after(() => { fs.promises.open = originalOpen; });
+}