feat(sidechat): 侧边对话——每对话一 Tab（Codex 对齐）+ 完整上下文继承 + 保存为新会话 (#286)

三轮实测驱动迭代：种子信封透传（surfaceOp 校验）、每线程一 Tab 交互重做完、四连修（fork 丢 this / 自绘 history+save 图标 / collectOwnEvents 大页回源修重开丢工具行 / descriptor 入种子修目录 corrupt 行 + 前缀过滤保拓扑零噪音）。739 单测 + 挂载冒烟 12/12 全绿。

src/client/locales.ts

@@ -247,6 +247,29 @@ export const zh = {
   subagentDiagUnsupported: '不支持的条目',
   subagentDiagUnavailable: '不可用',
   subagentThinking: '思考中…',
+  sideChat: '侧边对话',
+  sideChatNew: '新建对话',
+  sideChatUntitled: '新对话',
+  sideChatEmpty: '暂无侧边对话',
+  sideChatEmptyDesc: '每个侧边对话是标签栏里的独立 Tab，继承当前会话的上下文运行，不会进入主会话',
+  sideChatCreating: '正在创建侧边对话…',
+  sideChatRetry: '重试',
+  sideChatThreads: '切换线程 / 新建',
+  sideChatSave: '保存为新会话',
+  sideChatSaveTitle: '把该线程提升为顶层会话，出现在主会话列表中',
+  sideChatSaved: '已保存为新会话',
+  sideChatNoTurn: '至少完成一轮对话后才能保存',
+  sideChatPendingDrop: '最后一条未完成的追问不会包含在新会话中',
+  sideChatFirstPlaceholder: '输入第一个问题，已继承当前会话上下文…',
+  sideChatComposerPlaceholder: '追问…',
+  sideChatThinking: '正在深入…',
+  sideChatThink: '思考过程',
+  sideChatSend: '发送',
+  sideChatCancel: '停止',
+  sideChatCancelTitle: '中止当前回合（保留队列）',
+  sideChatClose: '关闭线程',
+  sideChatCloseTitle: '释放线程的 agent（历史保留）',
+  sideChatError: '侧边对话出错：{message}',
   jobs: '后台任务',
   jobsCount: '{count} 个后台任务',
   jobsCountRunning: '{count} 个后台任务 · {running} 运行中',
@@ -525,6 +548,29 @@ export const en: Record<keyof typeof zh, string> = {
   subagentDiagUnsupported: 'Unsupported',
   subagentDiagUnavailable: 'Unavailable',
   subagentThinking: 'Thinking…',
+  sideChat: 'Side Chat',
+  sideChatNew: 'New thread',
+  sideChatUntitled: 'New thread',
+  sideChatEmpty: 'No side conversations',
+  sideChatEmptyDesc: 'Every side conversation is its own tab in the tab strip — it inherits the current session\'s context and never enters the main conversation',
+  sideChatCreating: 'Creating side conversation…',
+  sideChatRetry: 'Retry',
+  sideChatThreads: 'Switch thread / new',
+  sideChatSave: 'Save as new session',
+  sideChatSaveTitle: 'Promote this thread to a top-level session in the main session list',
+  sideChatSaved: 'Saved as a new session',
+  sideChatNoTurn: 'Save is available after the first completed turn',
+  sideChatPendingDrop: 'The last unanswered follow-up will not be included in the saved session',
+  sideChatFirstPlaceholder: 'Ask the first question — context inherited…',
+  sideChatComposerPlaceholder: 'Ask a follow-up…',
+  sideChatThinking: 'Deep diving…',
+  sideChatThink: 'Thinking',
+  sideChatSend: 'Send',
+  sideChatCancel: 'Stop',
+  sideChatCancelTitle: 'Abort the running turn (queued work is kept)',
+  sideChatClose: 'Close thread',
+  sideChatCloseTitle: 'Release the thread\'s agent (history is kept)',
+  sideChatError: 'Side Chat error: {message}',
   jobs: 'Background jobs',
   jobsCount: '{count} background jobs',
   jobsCountRunning: '{count} background jobs · {running} running',