fix(remote-connect): refuse rollback mid-turn and refresh right after it lands

Two problems in the mobile rollback flow, both about the window between the
host mutation landing and the phone finding out.

`begin_session_maintenance` takes its permit by clearing the pending queue,
cancelling background subagents and cancelling the active turn, so a rollback
requested while the desktop is working silently destroys that work. The
desktop refuses instead: `assertSessionIdleForHistoryMutation` requires an
idle session and an empty queue. Match it — disable both menu entries and the
confirm button while a turn is active, guard the handler, and say why.

The transcript also stayed stale on the failure path. `nudge()` ran only after
the whole operation succeeded, so a rollback that landed followed by a failed
send left the retired turns on screen until the next idle poll, which is ten
seconds out. Nudge as soon as the rollback returns, before the send can fail.

Also:
- `.chat-msg__menu-sheet` had no height bound, so the edit sheet's autofocused
  textarea could raise the keyboard and push the confirm button out of an
  unscrollable sheet. Add `max-height: 85dvh` and `overflow-y: auto`.
- Edit mode reported `rollbackDone` ("Rolled back") after it had also sent the
  new turn. Give it its own string.

Author: BingCHuanJ

src/mobile-web/src/i18n/messages.ts

@@ -176,6 +176,8 @@ export const messages: Record<MobileLanguage, MessageTree> = {
       editPlaceholder: 'Edit this message...',
       rollbackDone: 'Rolled back',
       rollbackDoneRestored: 'Rolled back, {count} file(s) restored',
+      editDone: 'Rolled back and sent',
+      rollbackBlockedWhileBusy: 'Stop the running turn before changing history.',
       messageCopied: 'Copied',
       messageDeleted: 'Deleted',
       copyFailed: 'Copy failed',
@@ -378,6 +380,8 @@ export const messages: Record<MobileLanguage, MessageTree> = {
       editPlaceholder: '编辑这条消息...',
       rollbackDone: '已回滚',
       rollbackDoneRestored: '已回滚，还原了 {count} 个文件',
+      editDone: '已回滚并重新发送',
+      rollbackBlockedWhileBusy: '请先停止正在执行的轮次，再修改历史。',
       messageCopied: '已复制',
       messageDeleted: '已删除',
       copyFailed: '复制失败',
@@ -580,6 +584,8 @@ export const messages: Record<MobileLanguage, MessageTree> = {
       editPlaceholder: '編輯這條訊息...',
       rollbackDone: '已回溯',
       rollbackDoneRestored: '已回溯，還原了 {count} 個檔案',
+      editDone: '已回溯並重新送出',
+      rollbackBlockedWhileBusy: '請先停止正在執行的輪次，再修改歷史。',
       messageCopied: '已複製',
       messageDeleted: '已刪除',
       copyFailed: '複製失敗',

src/mobile-web/src/pages/ChatPage.tsx

@@ -2663,6 +2663,10 @@ const ChatPage: React.FC<ChatPageProps> = ({ sessionMgr, sessionId, sessionName,
   // message.
   const handleConfirmRollback = useCallback(async () => {
     if (!rollbackTarget || rollbackBusy) return;
+    // The host cancels the running turn and clears the queue to take the
+    // maintenance permit, so it never rolls back mid-task. Match the desktop,
+    // which refuses the mutation instead of killing work the user can't see.
+    if (isStreaming) return;
     const { message, mode } = rollbackTarget;
     const turnId = message.turn_id;
     if (!turnId) return;
@@ -2675,6 +2679,10 @@ const ChatPage: React.FC<ChatPageProps> = ({ sessionMgr, sessionId, sessionName,
     try {
       const result = await sessionMgr.rollbackSessionToTurn(sessionId, turnId, message.turn_index);
       if (!isChatTargetCurrent(targetEpoch)) return;
+      // History changed on the host. Pull the authoritative snapshot now, before
+      // the follow-up send can fail, or the transcript keeps showing turns that
+      // no longer exist until the next idle poll ten seconds later.
+      pollerRef.current?.nudge();
 
       if (mode === 'edit') {
         const imageContexts = message.images?.length
@@ -2704,9 +2712,11 @@ const ChatPage: React.FC<ChatPageProps> = ({ sessionMgr, sessionId, sessionName,
       }
 
       showMsgToast(
-        result.restored_files.length > 0
-          ? t('chat.rollbackDoneRestored', { count: result.restored_files.length })
-          : t('chat.rollbackDone'),
+        mode === 'edit'
+          ? t('chat.editDone')
+          : result.restored_files.length > 0
+            ? t('chat.rollbackDoneRestored', { count: result.restored_files.length })
+            : t('chat.rollbackDone'),
       );
       pollerRef.current?.nudge();
     } catch (e: any) {
@@ -2720,6 +2730,7 @@ const ChatPage: React.FC<ChatPageProps> = ({ sessionMgr, sessionId, sessionName,
     agentMode,
     captureChatTargetEpoch,
     isChatTargetCurrent,
+    isStreaming,
     rollbackBusy,
     rollbackDraft,
     rollbackTarget,
@@ -3433,20 +3444,31 @@ const ChatPage: React.FC<ChatPageProps> = ({ sessionMgr, sessionId, sessionName,
               )}
               {menuMessage.role === 'user' && !!menuMessage.turn_id && (
                 <>
-                  <button className="chat-msg__menu-btn" onClick={() => openRollbackSheet('edit')}>
+                  <button
+                    className="chat-msg__menu-btn"
+                    onClick={() => openRollbackSheet('edit')}
+                    disabled={isStreaming}
+                  >
                     <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.7" strokeLinecap="round" strokeLinejoin="round">
                       <path d="M11 4H4a2 2 0 0 0-2 2v14a2 2 0 0 0 2 2h14a2 2 0 0 0 2-2v-7" />
                       <path d="M18.5 2.5a2.121 2.121 0 0 1 3 3L12 15l-4 1 1-4z" />
                     </svg>
                     <span>{t('chat.editAndResend')}</span>
                   </button>
-                  <button className="chat-msg__menu-btn" onClick={() => openRollbackSheet('rollback')}>
+                  <button
+                    className="chat-msg__menu-btn"
+                    onClick={() => openRollbackSheet('rollback')}
+                    disabled={isStreaming}
+                  >
                     <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.7" strokeLinecap="round" strokeLinejoin="round">
                       <polyline points="1 4 1 10 7 10" />
                       <path d="M3.51 15a9 9 0 1 0 2.13-9.36L1 10" />
                     </svg>
                     <span>{t('chat.rollbackToHere')}</span>
                   </button>
+                  {isStreaming && (
+                    <p className="chat-msg__menu-note">{t('chat.rollbackBlockedWhileBusy')}</p>
+                  )}
                 </>
               )}
               <button
@@ -3493,12 +3515,15 @@ const ChatPage: React.FC<ChatPageProps> = ({ sessionMgr, sessionId, sessionName,
               ) : (
                 <p className="chat-msg__rollback-quote">{sanitizeMessageText(rollbackTarget.message.content)}</p>
               )}
+              {isStreaming && (
+                <p className="chat-msg__menu-note">{t('chat.rollbackBlockedWhileBusy')}</p>
+              )}
             </div>
             <div className="chat-msg__menu-actions">
               <button
                 className="chat-msg__menu-btn chat-msg__menu-btn--danger chat-msg__menu-btn--confirm"
                 onClick={handleConfirmRollback}
-                disabled={rollbackBusy || (rollbackTarget.mode === 'edit' && !rollbackDraft.trim())}
+                disabled={rollbackBusy || isStreaming || (rollbackTarget.mode === 'edit' && !rollbackDraft.trim())}
               >
                 <span>
                   {rollbackBusy

src/mobile-web/src/styles/components/chat.scss

@@ -364,6 +364,8 @@
 .chat-msg__menu-sheet {
   width: 100%;
   max-width: 440px;
+  max-height: 85dvh;
+  overflow-y: auto;
   background: var(--color-bg-elevated);
   border-radius: 20px 20px 0 0;
   padding: var(--size-gap-2) var(--size-gap-4) var(--size-gap-6);
@@ -430,6 +432,13 @@
   }
 }
 
+.chat-msg__menu-note {
+  margin: 0;
+  padding: 0 var(--size-gap-2);
+  font-size: var(--font-size-sm);
+  color: var(--color-text-secondary);
+}
+
 // ── Rollback / edit confirmation ──────────────────────────────────
 .chat-msg__rollback {
   display: flex;