feat(chat): 消息时间戳与操作提示边界（#439 #441）

docs/images/message-timestamps/README.md

@@ -0,0 +1,12 @@
+# 消息时间：真实页面对照
+
+前后图片均来自 Windows 上的 Chromium，使用生产构建和同一个本地 Go 服务、同一条已保存聊天。测试服务通过实际文件工具读取 README.md，返回离线验证回复；没有修改页面 DOM 来模拟消息或时间。
+
+- 基线：`10311148d5f581d68e4603e9a435c257015cc81d`。
+- 桌面视口：1280 × 900，见 [before.png](before.png) / [after.png](after.png)。
+- 窄视口：600 × 900，见 [before-narrow.png](before-narrow.png) / [after-narrow.png](after-narrow.png)。
+- 用户消息原始时间为 `2026-10-21T17:47:40.211Z`；助手消息为 `2026-10-21T17:47:40.402Z`。本机 UTC+8，界面均显示 `01:47`。
+- 实际页面的 `title` 与读屏标签包含 `2026年10月22日 GMT+8 01:47:40`，`time` 元素保留原始 ISO 时间。
+- 已检查两个视口中时间与复制、引用、分支等操作的排列。600 px 的正文横向滚动条在基线中也存在。
+
+15 项 narrative / narrative-streaming 聚焦测试及生产构建通过；测试覆盖缺失、无效时间和正在生成的回复。此次没有原生桌面打包验证。

docs/images/message-tooltips/README.md

@@ -0,0 +1,40 @@
+# 消息操作提示的窄屏边界
+
+用户消息位于聊天右侧，操作提示原来从按钮左边向右展开。即使提示处于 `visibility: hidden`，其宽度仍扩大聊天滚动区域；鼠标悬停或键盘聚焦时，提示末尾被裁掉。
+
+本次仅将 `.v2-user-actions .v2-assistant-action-tooltip` 改为 `left: auto; right: 0`，让用户消息提示向左展开。助手消息提示保留原有对齐方式。
+
+## 真实页面对照
+
+2026-10-22，Windows Edge。修改前使用 #439 / `ef6ae6b1` 的现成生产 bundle，修改后使用本工作树的生产构建。两套页面连接同一份 SQLite 中已保存的对话，使用生产 API；对话由 `cmd/workbenchjourney` 离线模型提供者实际读取 README 后生成。未替换 DOM、注入修复样式或拦截接口制造结果。
+
+600px 中文，鼠标悬停“引用消息”：
+
+| 修改前 | 修改后 |
+| --- | --- |
+| ![中文提示修改前](before-zh-CN-600-hover.png) | ![中文提示修改后](after-zh-CN-600-hover.png) |
+
+390px 英文，使用 Tab 聚焦“Quote message”：
+
+| 修改前 | 修改后 |
+| --- | --- |
+| ![英文提示修改前](before-en-US-390-focus.png) | ![英文提示修改后](after-en-US-390-focus.png) |
+
+## 尺寸与滚动检查
+
+以下各组都检查了初始隐藏状态，以及四个用户操作按钮逐一悬停、逐一键盘聚焦。修改后所有消息提示均位于聊天容器左右边界内。
+
+| 语言 / 视口宽度 | 聊天 clientWidth | 修改前 scrollWidth | 修改后 scrollWidth |
+| --- | ---: | ---: | ---: |
+| 中文 / 600px | 600 | 621 | 600 |
+| 中文 / 390px | 390 | 411 | 390 |
+| English / 600px | 600 | 704 | 600 |
+| English / 390px | 390 | 494 | 390 |
+
+[完整 DOM 尺寸记录](measurements.csv)包含每次测量的提示边界、可见状态和透明度。基线生产 bundle 摘要为 `ecb366bd9e5d692d8dedc260669f3ac456b31113ca1565b50b400add6f97752b`，修改后为 `ddca30555373a91473dd60bb522246d39fc0b39c5f3a023bafe0a216bfbdd945`。
+
+另从真实输入框发送并保存了带长行的 JavaScript 代码块。代码区域的 `scrollWidth` 为 2570px，在 600px / 390px 视口下自身宽度分别为 401px / 237px。横向滚轮将代码自身的 `scrollLeft` 分别推进至 1200px / 2000px；聊天容器保持 `scrollLeft=0`，且 `scrollWidth=clientWidth`。完整代码原文保留。[滚动测量](code-scroll.json)
+
+![390px 代码块内部横向滚动](after-code-scroll-390.png)
+
+`npm run build` 通过。以上为生产网页验证，未作为原生打包窗口验证。

docs/images/message-tooltips/code-scroll.json

@@ -0,0 +1,34 @@
+[
+  {
+    "width": 600,
+    "before": {
+      "clientWidth": 401,
+      "scrollWidth": 2570,
+      "scrollLeft": 400,
+      "overflowX": "auto"
+    },
+    "after": {
+      "codeLeft": 1200,
+      "chatLeft": 0,
+      "chatWidth": 600,
+      "chatScrollWidth": 600,
+      "fullCodePreserved": true
+    }
+  },
+  {
+    "width": 390,
+    "before": {
+      "clientWidth": 237,
+      "scrollWidth": 2570,
+      "scrollLeft": 1200,
+      "overflowX": "auto"
+    },
+    "after": {
+      "codeLeft": 2000,
+      "chatLeft": 0,
+      "chatWidth": 390,
+      "chatScrollWidth": 390,
+      "fullCodePreserved": true
+    }
+  }
+]

docs/images/message-tooltips/measurements.csv

@@ -0,0 +1,73 @@
+"phase","locale","viewportWidth","state","buttonIndex","clientWidth","scrollWidth","minTooltipLeft","maxTooltipRight","measuredTooltip","tooltipLeft","tooltipRight","visibility","opacity"
+"before","zh-CN","600","idle",,"600","621","20","620.515625","引用选中文字或整条消息","481.515625","620.515625","hidden","0"
+"before","zh-CN","600","hover","0","600","621","20","620.515625","复制消息","417.515625","479.515625","visible","1"
+"before","zh-CN","600","hover","1","600","621","20","620.515625","回填文字到输入框","449.515625","555.515625","visible","1"
+"before","zh-CN","600","hover","2","600","621","20","620.515625","引用选中文字或整条消息","481.515625","620.515625","visible","1"
+"before","zh-CN","600","hover","3","600","621","20","620.515625","分支到新聊天","513.515625","597.515625","visible","1"
+"before","zh-CN","600","focus","0","600","621","20","620.515625","复制消息","417.515625","479.515625","visible","1"
+"before","zh-CN","600","focus","1","600","621","20","620.515625","回填文字到输入框","449.515625","555.515625","visible","1"
+"before","zh-CN","600","focus","2","600","621","20","620.515625","引用选中文字或整条消息","481.515625","620.515625","visible","1"
+"before","zh-CN","600","focus","3","600","621","20","620.515625","分支到新聊天","513.515625","597.515625","visible","1"
+"before","zh-CN","390","idle",,"390","411","20","410.515625","引用选中文字或整条消息","271.515625","410.515625","hidden","0"
+"before","zh-CN","390","hover","0","390","411","20","410.515625","复制消息","207.515625","269.515625","visible","1"
+"before","zh-CN","390","hover","1","390","411","20","410.515625","回填文字到输入框","239.515625","345.515625","visible","1"
+"before","zh-CN","390","hover","2","390","411","20","410.515625","引用选中文字或整条消息","271.515625","410.515625","visible","1"
+"before","zh-CN","390","hover","3","390","411","20","410.515625","分支到新聊天","303.515625","387.515625","visible","1"
+"before","zh-CN","390","focus","0","390","411","20","410.515625","复制消息","207.515625","269.515625","visible","1"
+"before","zh-CN","390","focus","1","390","411","20","410.515625","回填文字到输入框","239.515625","345.515625","visible","1"
+"before","zh-CN","390","focus","2","390","411","20","410.515625","引用选中文字或整条消息","271.515625","410.515625","visible","1"
+"before","zh-CN","390","focus","3","390","411","20","410.515625","分支到新聊天","303.515625","387.515625","visible","1"
+"before","en-US","600","idle",,"600","704","20","703.578125","Quote selected text or the whole message","481.515625","703.578125","hidden","0"
+"before","en-US","600","hover","0","600","704","20","703.578125","Copy message","417.515625","505.96875","visible","1"
+"before","en-US","600","hover","1","600","704","20","703.578125","Reuse text in composer","449.515625","580.515625","visible","1"
+"before","en-US","600","hover","2","600","704","20","703.578125","Quote selected text or the whole message","481.515625","703.578125","visible","1"
+"before","en-US","600","hover","3","600","704","20","703.578125","Branch into new chat","513.515625","633.4375","visible","1"
+"before","en-US","600","focus","0","600","704","20","703.578125","Copy message","417.515625","505.96875","visible","1"
+"before","en-US","600","focus","1","600","704","20","703.578125","Reuse text in composer","449.515625","580.515625","visible","1"
+"before","en-US","600","focus","2","600","704","20","703.578125","Quote selected text or the whole message","481.515625","703.578125","visible","1"
+"before","en-US","600","focus","3","600","704","20","703.578125","Branch into new chat","513.515625","633.4375","visible","1"
+"before","en-US","390","idle",,"390","494","20","493.578125","Quote selected text or the whole message","271.515625","493.578125","hidden","0"
+"before","en-US","390","hover","0","390","494","20","493.578125","Copy message","207.515625","295.96875","visible","1"
+"before","en-US","390","hover","1","390","494","20","493.578125","Reuse text in composer","239.515625","370.515625","visible","1"
+"before","en-US","390","hover","2","390","494","20","493.578125","Quote selected text or the whole message","271.515625","493.578125","visible","1"
+"before","en-US","390","hover","3","390","494","20","493.578125","Branch into new chat","303.515625","423.4375","visible","1"
+"before","en-US","390","focus","0","390","494","20","493.578125","Copy message","207.515625","295.96875","visible","1"
+"before","en-US","390","focus","1","390","494","20","493.578125","Reuse text in composer","239.515625","370.515625","visible","1"
+"before","en-US","390","focus","2","390","494","20","493.578125","Quote selected text or the whole message","271.515625","493.578125","visible","1"
+"before","en-US","390","focus","3","390","494","20","493.578125","Branch into new chat","303.515625","423.4375","visible","1"
+"after","zh-CN","600","idle",,"600","600","20","541.515625","引用选中文字或整条消息","370.515625","509.515625","hidden","0"
+"after","zh-CN","600","hover","0","600","600","20","541.515625","复制消息","383.515625","445.515625","visible","1"
+"after","zh-CN","600","hover","1","600","600","20","541.515625","回填文字到输入框","371.515625","477.515625","visible","1"
+"after","zh-CN","600","hover","2","600","600","20","541.515625","引用选中文字或整条消息","370.515625","509.515625","visible","1"
+"after","zh-CN","600","hover","3","600","600","20","541.515625","分支到新聊天","457.515625","541.515625","visible","1"
+"after","zh-CN","600","focus","0","600","600","20","541.515625","复制消息","383.515625","445.515625","visible","1"
+"after","zh-CN","600","focus","1","600","600","20","541.515625","回填文字到输入框","371.515625","477.515625","visible","1"
+"after","zh-CN","600","focus","2","600","600","20","541.515625","引用选中文字或整条消息","370.515625","509.515625","visible","1"
+"after","zh-CN","600","focus","3","600","600","20","541.515625","分支到新聊天","457.515625","541.515625","visible","1"
+"after","zh-CN","390","idle",,"390","390","20","331.515625","引用选中文字或整条消息","160.515625","299.515625","hidden","0"
+"after","zh-CN","390","hover","0","390","390","20","331.515625","复制消息","173.515625","235.515625","visible","1"
+"after","zh-CN","390","hover","1","390","390","20","331.515625","回填文字到输入框","161.515625","267.515625","visible","1"
+"after","zh-CN","390","hover","2","390","390","20","331.515625","引用选中文字或整条消息","160.515625","299.515625","visible","1"
+"after","zh-CN","390","hover","3","390","390","20","331.515625","分支到新聊天","247.515625","331.515625","visible","1"
+"after","zh-CN","390","focus","0","390","390","20","331.515625","复制消息","173.515625","235.515625","visible","1"
+"after","zh-CN","390","focus","1","390","390","20","331.515625","回填文字到输入框","161.515625","267.515625","visible","1"
+"after","zh-CN","390","focus","2","390","390","20","331.515625","引用选中文字或整条消息","160.515625","299.515625","visible","1"
+"after","zh-CN","390","focus","3","390","390","20","331.515625","分支到新聊天","247.515625","331.515625","visible","1"
+"after","en-US","600","idle",,"600","600","20","541.515625","Quote selected text or the whole message","287.453125","509.515625","hidden","0"
+"after","en-US","600","hover","0","600","600","20","541.515625","Copy message","357.0625","445.515625","visible","1"
+"after","en-US","600","hover","1","600","600","20","541.515625","Reuse text in composer","346.515625","477.515625","visible","1"
+"after","en-US","600","hover","2","600","600","20","541.515625","Quote selected text or the whole message","287.453125","509.515625","visible","1"
+"after","en-US","600","hover","3","600","600","20","541.515625","Branch into new chat","421.59375","541.515625","visible","1"
+"after","en-US","600","focus","0","600","600","20","541.515625","Copy message","357.0625","445.515625","visible","1"
+"after","en-US","600","focus","1","600","600","20","541.515625","Reuse text in composer","346.515625","477.515625","visible","1"
+"after","en-US","600","focus","2","600","600","20","541.515625","Quote selected text or the whole message","287.453125","509.515625","visible","1"
+"after","en-US","600","focus","3","600","600","20","541.515625","Branch into new chat","421.59375","541.515625","visible","1"
+"after","en-US","390","idle",,"390","390","20","331.515625","Quote selected text or the whole message","77.453125","299.515625","hidden","0"
+"after","en-US","390","hover","0","390","390","20","331.515625","Copy message","147.0625","235.515625","visible","1"
+"after","en-US","390","hover","1","390","390","20","331.515625","Reuse text in composer","136.515625","267.515625","visible","1"
+"after","en-US","390","hover","2","390","390","20","331.515625","Quote selected text or the whole message","77.453125","299.515625","visible","1"
+"after","en-US","390","hover","3","390","390","20","331.515625","Branch into new chat","211.59375","331.515625","visible","1"
+"after","en-US","390","focus","0","390","390","20","331.515625","Copy message","147.0625","235.515625","visible","1"
+"after","en-US","390","focus","1","390","390","20","331.515625","Reuse text in composer","136.515625","267.515625","visible","1"
+"after","en-US","390","focus","2","390","390","20","331.515625","Quote selected text or the whole message","77.453125","299.515625","visible","1"
+"after","en-US","390","focus","3","390","390","20","331.515625","Branch into new chat","211.59375","331.515625","visible","1"

docs/usage.md

@@ -175,6 +175,9 @@ Ctrl+Shift+V（macOS 为 Cmd+Shift+V）按纯文本粘贴，保留 Markdown 标
 围栏块中；块顶部显示“文本”和复制按钮，复制内容不包含围栏。代码围栏显示语言名称。
 普通段落保留整条回复的复制入口。
 
+已保存的用户消息和助手回复在操作图标旁显示本地时间。悬停时间可查看完整日期、秒和时区；
+屏幕阅读器可读取同样的信息。仍在发送或生成的消息、没有有效原始时间的历史记录不显示时间。
+
 聊天正文使用 14 px 字号、1.625 倍行高和正常字距，代码块保持 13 px。
 已完成的段落采用智能换行，标题均衡换行，长标识符在空间不足时折行。
 实时回复的新片段以 150 ms 的轻微模糊淡入显示，不额外等待或延迟输出；历史消息和

web/src/v2/components/narrative.test.tsx

@@ -9,6 +9,27 @@ const markdown = vi.hoisted(() => vi.fn(({ children }: { children: string }) =>
 vi.mock("react-markdown", () => ({ default: markdown }));
 afterEach(() => { cleanup(); markdown.mockClear(); });
 
+it("shows stored message times with a full local date and timezone, without replacing missing timestamps", () => {
+  const createdAt = "2026-10-21T09:16:43Z";
+  const entries: NarrativeEntry[] = [
+    { id: "user", kind: "user", text: "Request", createdAt, provisional: false },
+    { id: "reply", kind: "assistant", text: "Reply", createdAt, provisional: false },
+    { id: "missing", kind: "assistant", text: "Older reply", createdAt: "", provisional: false },
+    { id: "invalid", kind: "assistant", text: "Invalid time", createdAt: "invalid", provisional: false },
+    { id: "live", kind: "assistant", text: "Streaming", createdAt, provisional: true },
+  ];
+  const { container } = render(<V2Narrative client={{} as APIClient} entries={entries} threadID="thread" />);
+  const times = container.querySelectorAll("time");
+  expect(times).toHaveLength(2);
+  for (const time of times) {
+    expect(time).toHaveAttribute("datetime", "2026-10-21T09:16:43.000Z");
+    expect(time.textContent).toMatch(/^\d{2}:\d{2}$/u);
+    expect(time.title).toContain("2026");
+    expect(time.title).toContain("43");
+    expect(time).toHaveAccessibleName("Message time: " + time.title);
+  }
+});
+
 it("copies and reuses processed user text, quotes only the selection, and branches from that input", async () => {
   const user = userEvent.setup();
   const writeText = vi.spyOn(navigator.clipboard, "writeText").mockResolvedValue(undefined);