feat(conversation): replicate WorkBuddy rewind-to-message action (TODO 05)

src/main/ipc.ts

@@ -509,12 +509,13 @@ export function registerIpc(getWindow: () => BrowserWindow | null): void {
     if ([...runTasks.values()].some((run) => run.sessionId === sessionId)) throw new Error('请先停止当前运行')
     const history = [...await sessions.getMessages(sessionId)]
     const index = history.findIndex((item) => item.id === messageId && item.role === 'user')
+    if (index < 0) throw new Error('未找到用户消息')
     const changes = getRevertChanges(history, messageId)
-    if (!changes.length) throw new Error('此版本没有可恢复的文件修改')
     const workspace = await sessionRoot(sessionId)
     const kernel = await getOmpKernel(sessionId, workspace, await models.resolveModel((await sessions.getSessionContext(sessionId)).modelId))
     if (kernel && !history[index].nativeEntryId) throw new Error('缺少原生会话分支，无法同时恢复上下文')
-    const undo = await restoreWorkspaceFiles(workspace, changes)
+    // 原版 rewind 的 no-version 变体：没有产物版本时仅回退对话内容，不触碰文件。
+    const undo = changes.length ? await restoreWorkspaceFiles(workspace, changes) : async () => undefined
     try {
       if (kernel) {
         const response = await kernel.branch(history[index].nativeEntryId!)