Improve live camera relay buffering

client/src/lib/changelog.ts

@@ -8,11 +8,34 @@ export type ChangeLogEntry = {
 };
 
 export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
+  {
+    version: "2026.03.17-live-camera-relay-buffer",
+    releaseDate: "2026-03-17",
+    repoVersion: "63dbfd2+relay-buffer",
+    summary:
+      "实时分析同步观看改为服务端滚动视频缓存，观看端不再轮询单帧图片；media 服务同时新增最近 60 秒缓冲和 30 分钟缓存清理。",
+    features: [
+      "live-camera owner 端的 60 秒合成录像分段现在会额外上传到 media relay 会话，观看端改为播放服务端生成的滚动 preview 视频，不再依赖 `live-frame.jpg` 单帧轮询",
+      "relay 会话只保留最近 60 秒分段，worker 会在新分段到达后按最新窗口重建 `preview.webm`，避免观看端继续看到旧一分钟缓存",
+      "超过 30 分钟无活动的 relay 会话、分段目录和公开缓存文件会自动清理，避免多端同步长期堆积无用缓存",
+      "实时分析 viewer 文案和占位提示同步调整为“缓冲最近 60 秒视频 / 加载缓存回放”，更贴近现在的服务端缓存播放行为",
+      "media preview 非归档阶段跳过 mp4 转码，Chrome 观看直接使用 webm，降低 worker 处理时延和 CPU 消耗",
+    ],
+    tests: [
+      "cd media && go test ./...",
+      "pnpm vitest run client/src/lib/liveCamera.test.ts",
+      'pnpm exec playwright test tests/e2e/app.spec.ts --grep "live camera page exposes camera startup controls|live camera starts analysis and produces scores|live camera switches into viewer mode when another device already owns analysis|live camera recovers mojibake viewer titles before rendering|live camera no longer opens viewer peer retries when server relay is active"',
+      "pnpm check",
+      "pnpm build",
+      "线上 smoke: 部署后确认 `https://te.hao.work/` 已提供新构建而不是旧资源版本，`/live-camera` viewer 端进入“服务端缓存同步”路径并返回正确的 JS/CSS MIME",
+    ],
+  },
   {
     version: "2026.03.17-live-camera-preview-recovery",
     releaseDate: "2026-03-17",
     repoVersion: "06b9701",
-    summary: "修复实时分析页标题乱码、同步观看残留状态导致的黑屏，以及切回本机摄像头后预览无法恢复的问题。",
+    summary:
+      "修复实时分析页标题乱码、同步观看残留状态导致的黑屏，以及切回本机摄像头后预览无法恢复的问题。",
     features: [
       "runtime 标题恢复逻辑新增更严格的乱码筛除与二次 UTF-8 解码兜底，`服...`、带替换字符的脏标题现在会优先恢复为正常中文，无法恢复时会安全回退到稳定默认标题",
       "同步观看退出时会完整重置 viewer 轮询、连接标记和帧版本，不再把旧 viewer 状态残留到 owner 或空闲态，避免页面继续停留在黑屏或“等待同步画面”",
@@ -22,7 +45,7 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     tests: [
       "pnpm check",
       "pnpm vitest run client/src/lib/liveCamera.test.ts",
-      "pnpm exec playwright test tests/e2e/app.spec.ts --grep \"live camera\"",
+      'pnpm exec playwright test tests/e2e/app.spec.ts --grep "live camera"',
       "pnpm build",
       "线上 smoke: `curl -I https://te.hao.work/`，并检查页面源码中的 `/assets/index-*.js`、`/assets/index-*.css`、`/assets/pose-*.js` 已切换到新构建且返回正确 MIME",
     ],
@@ -31,7 +54,8 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     version: "2026.03.16-live-camera-runtime-refresh",
     releaseDate: "2026-03-16",
     repoVersion: "8e9e491",
-    summary: "修复实时分析页偶发残留在同步观看状态、标题乱码，以及摄像头预览绑定波动导致的启动失败。",
+    summary:
+      "修复实时分析页偶发残留在同步观看状态、标题乱码，以及摄像头预览绑定波动导致的启动失败。",
     features: [
       "live-camera 在打开拍摄引导、启用摄像头、开始分析前，都会先向服务端强制刷新 runtime 状态，避免旧的 viewer 锁残留导致本机明明已释放却仍无法启动",
       "同步观看标题新增乱码恢复逻辑，可自动把 UTF-8 被误按 Latin-1 显示的标题恢复成正常中文，避免出现 `服...` 一类异常标题",
@@ -39,7 +63,7 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
       "e2e mock 的媒体流补齐为带假视频轨道的流对象，并把 viewer 回归改为校验“服务端 relay、无 viewer-signal”行为，减少和旧 P2P 逻辑混淆",
     ],
     tests: [
-      "pnpm exec playwright test tests/e2e/app.spec.ts --grep \"live camera page exposes camera startup controls|live camera switches into viewer mode when another device already owns analysis|live camera recovers mojibake viewer titles before rendering|live camera no longer opens viewer peer retries when server relay is active\"",
+      'pnpm exec playwright test tests/e2e/app.spec.ts --grep "live camera page exposes camera startup controls|live camera switches into viewer mode when another device already owns analysis|live camera recovers mojibake viewer titles before rendering|live camera no longer opens viewer peer retries when server relay is active"',
       "pnpm build",
       "部署后线上 smoke: `https://te.hao.work/live-camera` 登录 H1 后可见空闲态“启动摄像头”入口，确认不再被残留 viewer 锁卡住；公开站点前端资源为 `assets/index-33wVjC4p.js` 与 `assets/index-tNGuStgv.css`",
     ],
@@ -48,7 +72,8 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     version: "2026.03.16-live-viewer-server-relay",
     releaseDate: "2026-03-16",
     repoVersion: "bb46d26",
-    summary: "实时分析同步观看改为由 media 服务中转帧图，不再依赖浏览器之间的 P2P 视频连接。",
+    summary:
+      "实时分析同步观看改为由 media 服务中转帧图，不再依赖浏览器之间的 P2P 视频连接。",
     features: [
       "owner 端现在会把带骨架、关键点和虚拟形象叠层的合成画布压缩成 JPEG 并持续上传到 media 服务",
       "viewer 端改为直接拉取 media 服务中的最新同步帧图，不再建立 WebRTC viewer peer 连接，因此跨网络和多端观看更稳定",
@@ -65,7 +90,8 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     version: "2026.03.16-camera-startup-fallbacks",
     releaseDate: "2026-03-16",
     repoVersion: "a211562",
-    summary: "修复部分设备上摄像头因后置镜头约束、分辨率约束或麦克风不可用而直接启动失败的问题。",
+    summary:
+      "修复部分设备上摄像头因后置镜头约束、分辨率约束或麦克风不可用而直接启动失败的问题。",
     features: [
       "live-camera 与 recorder 改为共用分级降级的摄像头请求流程，会在当前画质失败时自动降分辨率、降约束并回退到兼容镜头",
       "当设备不支持默认后置摄像头或当前镜头不可用时，页面会自动切换到实际可用的镜头方向，避免直接报错后卡死在未启动状态",
@@ -81,7 +107,8 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     version: "2026.03.16-live-analysis-viewer-full-sync",
     releaseDate: "2026-03-16",
     repoVersion: "922a9fb",
-    summary: "多端同步观看改为按持有端快照完整渲染，另一设备可同步看到视频状态、模式、画质、虚拟形象和保存阶段信息。",
+    summary:
+      "多端同步观看改为按持有端快照完整渲染，另一设备可同步看到视频状态、模式、画质、虚拟形象和保存阶段信息。",
     features: [
       "viewer 端现在同步显示持有端的会话标题、训练模式、设备端、拍摄视角、画质模式、虚拟形象状态和最近同步时间",
       "同步观看时的分析阶段、保存阶段、已完成状态也会跟随主端刷新，不再只显示本地默认状态",
@@ -89,7 +116,7 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
       "新增 viewer 同步信息卡，明确允许 1 秒级延迟，并持续显示最近心跳时间",
     ],
     tests: [
-      "pnpm exec playwright test tests/e2e/app.spec.ts --grep \"live camera switches into viewer mode|viewer stream|recorder blocks\"",
+      'pnpm exec playwright test tests/e2e/app.spec.ts --grep "live camera switches into viewer mode|viewer stream|recorder blocks"',
       "pnpm build",
       "部署后线上 smoke: `https://te.hao.work/` 已提供 `assets/index-HRdM3fxq.js` 与 `assets/index-tNGuStgv.css`；同账号 H1 双端登录后，移动端 owner 可开始实时分析，桌面端 `/live-camera` 自动进入同步观看并显示主端信息、同步视频流，owner 点击结束分析后 viewer 会同步进入保存阶段",
     ],
@@ -98,7 +125,8 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     version: "2026.03.16-live-analysis-lock-hardening",
     releaseDate: "2026-03-16",
     repoVersion: "f9db6ef",
-    summary: "修复同账号多端实时分析在旧登录态下仍可重复占用摄像头的问题，补强同步观看重试、录制页占用锁，并修复部署后启动阶段长时间 502。",
+    summary:
+      "修复同账号多端实时分析在旧登录态下仍可重复占用摄像头的问题，补强同步观看重试、录制页占用锁，并修复部署后启动阶段长时间 502。",
     features: [
       "旧用户名登录 token 即使缺少 `sid`，现在也会按 token 本身派生唯一会话标识，不再把不同设备错误识别成同一持有端",
       "同步观看模式新增 viewer 自动重试：当持有端刚启动推流、viewer 首次连接返回 `viewer stream not ready` 时，会自动重连而不是一直黑屏",
@@ -110,7 +138,7 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
       "curl -I https://te.hao.work/",
       "pnpm check",
       "pnpm exec vitest run server/_core/sdk.test.ts server/features.test.ts",
-      "pnpm exec playwright test tests/e2e/app.spec.ts --grep \"viewer mode|viewer stream|recorder blocks\"",
+      'pnpm exec playwright test tests/e2e/app.spec.ts --grep "viewer mode|viewer stream|recorder blocks"',
       "pnpm build",
       "线上 smoke: H1 手机端开启实时分析后，PC 端 `/live-camera` 自动进入同步观看并显示同步画面，`/recorder` 禁止启动摄像头；结束分析后会话可正常释放",
     ],
@@ -119,7 +147,8 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     version: "2026.03.16-live-analysis-runtime-migration",
     releaseDate: "2026-03-16",
     repoVersion: "2b72ef9",
-    summary: "修复实时分析因缺失 `live_analysis_runtime` 表导致的启动失败，并补齐迁移记录避免后续部署再次漏表。",
+    summary:
+      "修复实时分析因缺失 `live_analysis_runtime` 表导致的启动失败，并补齐迁移记录避免后续部署再次漏表。",
     features: [
       "生产库补建 `live_analysis_runtime` 表，并补写 `__drizzle_migrations` 中缺失的 `0011_live_analysis_runtime` 记录",
       "仓库内 Drizzle migration journal 补齐 `0011_live_analysis_runtime` 条目，后续 `docker compose` 部署可正确感知该迁移",
@@ -139,7 +168,8 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     version: "2026.03.16-live-camera-multidevice-viewer",
     releaseDate: "2026-03-16",
     repoVersion: "4e4122d",
-    summary: "实时分析新增同账号多端互斥和同步观看模式，分析持有端独占摄像头，其它端只能查看同步画面与核心识别结果。",
+    summary:
+      "实时分析新增同账号多端互斥和同步观看模式，分析持有端独占摄像头，其它端只能查看同步画面与核心识别结果。",
     features: [
       "同一账号在 `/live-camera` 进入实时分析后，会写入按用户维度的 runtime 锁，其他设备不能重复启动摄像头或分析",
       "其他设备会自动进入“同步观看模式”，可订阅持有端的实时画面，并同步看到动作、评分、反馈、最近片段和归档段数",
@@ -152,8 +182,8 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
       "pnpm exec vitest run server/features.test.ts",
       "go test ./... && go build ./... (media)",
       "pnpm build",
-      "pnpm exec playwright test tests/e2e/app.spec.ts --grep \"live camera\"",
+      'pnpm exec playwright test tests/e2e/app.spec.ts --grep "live camera"',
-      "pnpm exec playwright test tests/e2e/app.spec.ts --grep \"recorder flow archives a session and exposes it in videos\"",
+      'pnpm exec playwright test tests/e2e/app.spec.ts --grep "recorder flow archives a session and exposes it in videos"',
       "curl -I https://te.hao.work/live-camera",
     ],
   },
@@ -161,7 +191,8 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     version: "2026.03.16-live-analysis-overlay-archive",
     releaseDate: "2026-03-16",
     repoVersion: "4fb2d09",
-    summary: "实时分析新增 60 秒自动归档录像，录制内容会保留骨架、关键点和虚拟形象叠层，并同步进入视频库。",
+    summary:
+      "实时分析新增 60 秒自动归档录像，录制内容会保留骨架、关键点和虚拟形象叠层，并同步进入视频库。",
     features: [
       "实时分析开始后会自动录制合成画布，每 60 秒自动切段归档",
       "归档录像会保留原视频、骨架线、关键点和当前虚拟形象覆盖效果",
@@ -181,17 +212,15 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     version: "2026.03.15-live-analysis-leave-hint",
     releaseDate: "2026-03-15",
     repoVersion: "5c2dcf2",
-    summary: "实时分析结束后增加离开提示，明确何时必须停留、何时可以安全关闭或切页。",
+    summary:
+      "实时分析结束后增加离开提示，明确何时必须停留、何时可以安全关闭或切页。",
     features: [
       "分析进行中显示“不要关闭或切走页面”提示",
       "结束分析后保存阶段显示“请暂时停留当前页面”提示",
       "保存成功后明确提示“现在可以关闭浏览器或切换到其他页面”",
       "分析中和保存中挂接 beforeunload 提醒，减少误关页面导致的数据丢失",
     ],
-    tests: [
+    tests: ["pnpm check", "pnpm build"],
-      "pnpm check",
-      "pnpm build",
-    ],
   },
   {
     version: "2026.03.15-training-generator-collapse",
@@ -204,10 +233,7 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
       "移动端继续直接展示完整生成器，避免隐藏关键操作",
       "未生成计划时点击“前往生成训练计划”会自动展开并滚动到生成面板",
     ],
-    tests: [
+    tests: ["pnpm check", "pnpm build"],
-      "pnpm check",
-      "pnpm build",
-    ],
   },
   {
     version: "2026.03.15-progress-time-actions",
@@ -220,10 +246,7 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
       "展开态动作明细统一用中文动作标签展示",
       "提醒页通知时间统一切换为 Asia/Shanghai",
     ],
-    tests: [
+    tests: ["pnpm check", "pnpm build"],
-      "pnpm check",
-      "pnpm build",
-    ],
   },
   {
     version: "2026.03.15-session-changelog",
@@ -275,7 +298,7 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
     ],
     tests: [
       "pnpm check",
-      "pnpm exec vitest run server/features.test.ts -t \"video\\\\.\"",
+      'pnpm exec vitest run server/features.test.ts -t "video\\\\."',
       "Playwright 真实站点完成 /videos 新增-编辑-删除全链路",
     ],
   },
@@ -290,8 +313,6 @@ export const CHANGE_LOG_ENTRIES: ChangeLogEntry[] = [
       "训练提醒通知",
       "通知历史管理",
     ],
-    tests: [
+    tests: ["教程库、提醒、通知相关测试通过"],
-      "教程库、提醒、通知相关测试通过",
-    ],
   },
 ];

client/src/lib/media.ts

@@ -14,11 +14,7 @@ export type ArchiveStatus =
   | "completed"
   | "failed";
 
-export type PreviewStatus =
+export type PreviewStatus = "idle" | "processing" | "ready" | "failed";
-  | "idle"
-  | "processing"
-  | "ready"
-  | "failed";
 
 export type MediaMarker = {
   id: string;
@@ -33,6 +29,7 @@ export type MediaSession = {
   id: string;
   userId: string;
   title: string;
+  purpose?: "recording" | "relay";
   status: MediaSessionStatus;
   archiveStatus: ArchiveStatus;
   previewStatus: PreviewStatus;
@@ -64,11 +61,14 @@ export type MediaSession = {
   markers: MediaMarker[];
 };
 
-const MEDIA_BASE = (import.meta.env.VITE_MEDIA_BASE_URL || "/media").replace(/\/$/, "");
+const MEDIA_BASE = (import.meta.env.VITE_MEDIA_BASE_URL || "/media").replace(
+  /\/$/,
+  ""
+);
 const RETRYABLE_STATUS = new Set([502, 503, 504]);
 
 function sleep(ms: number) {
-  return new Promise((resolve) => setTimeout(resolve, ms));
+  return new Promise(resolve => setTimeout(resolve, ms));
 }
 
 async function request<T>(path: string, init?: RequestInit): Promise<T> {
@@ -79,7 +79,11 @@ async function request<T>(path: string, init?: RequestInit): Promise<T> {
       const response = await fetch(`${MEDIA_BASE}${path}`, init);
       if (!response.ok) {
         const errorBody = await response.json().catch(() => ({}));
-        const error = new Error(errorBody.error || errorBody.message || `Media service error (${response.status})`);
+        const error = new Error(
+          errorBody.error ||
+            errorBody.message ||
+            `Media service error (${response.status})`
+        );
         if (RETRYABLE_STATUS.has(response.status) && attempt < 2) {
           lastError = error;
           await sleep(400 * (attempt + 1));
@@ -89,7 +93,8 @@ async function request<T>(path: string, init?: RequestInit): Promise<T> {
       }
       return response.json() as Promise<T>;
     } catch (error) {
-      lastError = error instanceof Error ? error : new Error("Media request failed");
+      lastError =
+        error instanceof Error ? error : new Error("Media request failed");
       if (attempt < 2) {
         await sleep(400 * (attempt + 1));
         continue;
@@ -109,6 +114,7 @@ export async function createMediaSession(payload: {
   qualityPreset: string;
   facingMode: string;
   deviceKind: string;
+  purpose?: "recording" | "relay";
 }) {
   return request<{ session: MediaSession }>("/sessions", {
     method: "POST",
@@ -117,28 +123,43 @@ export async function createMediaSession(payload: {
   });
 }
 
-export async function signalMediaSession(sessionId: string, payload: { sdp: string; type: string }) {
+export async function signalMediaSession(
-  return request<{ sdp: string; type: string }>(`/sessions/${sessionId}/signal`, {
+  sessionId: string,
+  payload: { sdp: string; type: string }
+) {
+  return request<{ sdp: string; type: string }>(
+    `/sessions/${sessionId}/signal`,
+    {
       method: "POST",
       headers: { "Content-Type": "application/json" },
       body: JSON.stringify(payload),
-  });
+    }
+  );
 }
 
-export async function signalMediaViewerSession(sessionId: string, payload: { sdp: string; type: string }) {
+export async function signalMediaViewerSession(
-  return request<{ viewerId: string; sdp: string; type: string }>(`/sessions/${sessionId}/viewer-signal`, {
+  sessionId: string,
+  payload: { sdp: string; type: string }
+) {
+  return request<{ viewerId: string; sdp: string; type: string }>(
+    `/sessions/${sessionId}/viewer-signal`,
+    {
       method: "POST",
       headers: { "Content-Type": "application/json" },
       body: JSON.stringify(payload),
-  });
+    }
+  );
 }
 
 export async function uploadMediaLiveFrame(sessionId: string, blob: Blob) {
-  return request<{ session: MediaSession }>(`/sessions/${sessionId}/live-frame`, {
+  return request<{ session: MediaSession }>(
+    `/sessions/${sessionId}/live-frame`,
+    {
       method: "POST",
       headers: { "Content-Type": blob.type || "image/jpeg" },
       body: blob,
-  });
+    }
+  );
 }
 
 export async function uploadMediaSegment(
@@ -159,7 +180,12 @@ export async function uploadMediaSegment(
 
 export async function createMediaMarker(
   sessionId: string,
-  payload: { type: string; label: string; timestampMs: number; confidence?: number }
+  payload: {
+    type: string;
+    label: string;
+    timestampMs: number;
+    confidence?: number;
+  }
 ) {
   return request<{ session: MediaSession }>(`/sessions/${sessionId}/markers`, {
     method: "POST",
@@ -201,7 +227,11 @@ export function pickRecorderMimeType() {
     "video/webm;codecs=h264,opus",
     "video/webm",
   ];
-  return candidates.find((candidate) => window.MediaRecorder?.isTypeSupported(candidate)) || "video/webm";
+  return (
+    candidates.find(candidate =>
+      window.MediaRecorder?.isTypeSupported(candidate)
+    ) || "video/webm"
+  );
 }
 
 export function pickBitrate(preset: string, isMobile: boolean) {

docs/CHANGELOG.md

@@ -1,5 +1,34 @@
 # Tennis Training Hub - 变更日志
 
+## 2026.03.17-live-camera-relay-buffer (2026-03-17)
+
+### 功能更新
+
+- `/live-camera` 的同步观看改为播放 media 服务生成的滚动缓存视频，不再轮询 `live-frame.jpg` 单帧图片，因此观看端的画面会按最近 60 秒缓存视频平滑播放
+- owner 端每个 60 秒的合成录像分段现在会额外上传到 `relay` 会话，worker 会在收到新分段后自动重建最近窗口的 `preview.webm`
+- `relay` 会话只保留最近 60 秒视频分段，旧分段会从会话元数据和磁盘同步清理，避免观看端继续读到旧一分钟之前的缓存
+- media worker 会自动清理超过 30 分钟无活动的 relay 会话、分段目录和公开缓存文件，降低磁盘堆积风险
+- viewer 页面文案、加载提示和按钮文案已同步更新为“缓存视频 / 缓存回放”语义；预览阶段跳过 mp4 转码，Chrome 直接使用 webm，降低处理时延
+
+### 测试
+
+- `cd media && go test ./...`
+- `pnpm vitest run client/src/lib/liveCamera.test.ts`
+- `pnpm exec playwright test tests/e2e/app.spec.ts --grep "live camera page exposes camera startup controls|live camera starts analysis and produces scores|live camera switches into viewer mode when another device already owns analysis|live camera recovers mojibake viewer titles before rendering|live camera no longer opens viewer peer retries when server relay is active"`
+- `pnpm check`
+- `pnpm build`
+- 线上 smoke：部署后确认 `https://te.hao.work/` 已提供新构建而不是旧资源版本，`/live-camera` viewer 端进入“服务端缓存同步”路径，首页与资源文件返回正确 MIME
+
+### 线上 smoke
+
+- 部署完成后已确认 `https://te.hao.work/` 提供的是本次新构建，而不是旧资源版本
+- `https://te.hao.work/live-camera` 的 viewer 端会走“服务端缓存同步”路径，不再请求旧的 `live-frame.jpg` 单帧同步
+- 首页、主 JS、主 CSS 与 `pose` 模块均返回 `200` 和正确 MIME，未再出现脚本/样式被回退成 `text/html` 的问题
+
+### 仓库版本
+
+- `63dbfd2+relay-buffer`
+
 ## 2026.03.17-live-camera-preview-recovery (2026-03-17)
 
 ### 功能更新

media/main.go

@@ -53,6 +53,18 @@ const (
 	PreviewFailed     PreviewStatus = "failed"
 )
 
+type SessionPurpose string
+
+const (
+	PurposeRecording SessionPurpose = "recording"
+	PurposeRelay     SessionPurpose = "relay"
+)
+
+const (
+	relayPreviewWindow = 60 * time.Second
+	relayCacheTTL      = 30 * time.Minute
+)
+
 type PlaybackInfo struct {
 	WebMURL    string `json:"webmUrl,omitempty"`
 	MP4URL     string `json:"mp4Url,omitempty"`
@@ -84,6 +96,7 @@ type Session struct {
 	ID               string         `json:"id"`
 	UserID           string         `json:"userId"`
 	Title            string         `json:"title"`
+	Purpose          SessionPurpose `json:"purpose"`
 	Status           SessionStatus  `json:"status"`
 	ArchiveStatus    ArchiveStatus  `json:"archiveStatus"`
 	PreviewStatus    PreviewStatus  `json:"previewStatus"`
@@ -134,6 +147,7 @@ type CreateSessionRequest struct {
 	QualityPreset string `json:"qualityPreset"`
 	FacingMode    string `json:"facingMode"`
 	DeviceKind    string `json:"deviceKind"`
+	Purpose       string `json:"purpose"`
 }
 
 type SignalRequest struct {
@@ -213,6 +227,12 @@ func (s *sessionStore) refreshFromDisk() error {
 	if err != nil {
 		return err
 	}
+	for _, session := range sessions {
+		if session.Purpose == "" {
+			session.Purpose = PurposeRecording
+		}
+		session.recomputeAggregates()
+	}
 	s.mu.Lock()
 	defer s.mu.Unlock()
 	s.sessions = sessions
@@ -265,6 +285,7 @@ func (s *sessionStore) createSession(input CreateSessionRequest) (*Session, erro
 		ID:            randomID(),
 		UserID:        strings.TrimSpace(input.UserID),
 		Title:         strings.TrimSpace(input.Title),
+		Purpose:       SessionPurpose(defaultString(input.Purpose, string(PurposeRecording))),
 		Status:        StatusCreated,
 		ArchiveStatus: ArchiveIdle,
 		PreviewStatus: PreviewIdle,
@@ -290,6 +311,106 @@ func (s *sessionStore) createSession(input CreateSessionRequest) (*Session, erro
 	return cloneSession(session), nil
 }
 
+func parseSessionTime(values ...string) time.Time {
+	for _, value := range values {
+		if strings.TrimSpace(value) == "" {
+			continue
+		}
+		if parsed, err := time.Parse(time.RFC3339, value); err == nil {
+			return parsed
+		}
+	}
+	return time.Time{}
+}
+
+func sortSegmentsBySequence(segments []SegmentMeta) {
+	sort.Slice(segments, func(i, j int) bool {
+		return segments[i].Sequence < segments[j].Sequence
+	})
+}
+
+func maxInt64(value int64, minimum int64) int64 {
+	if value < minimum {
+		return minimum
+	}
+	return value
+}
+
+func trimSegmentsToDuration(segments []SegmentMeta, maxDuration time.Duration) (kept []SegmentMeta, removed []SegmentMeta) {
+	if len(segments) == 0 {
+		return []SegmentMeta{}, []SegmentMeta{}
+	}
+
+	limitMS := maxDuration.Milliseconds()
+	total := int64(0)
+	startIndex := len(segments) - 1
+
+	for index := len(segments) - 1; index >= 0; index-- {
+		total += maxInt64(segments[index].DurationMS, 1)
+		startIndex = index
+		if total >= limitMS {
+			break
+		}
+	}
+
+	kept = append([]SegmentMeta(nil), segments[startIndex:]...)
+	removed = append([]SegmentMeta(nil), segments[:startIndex]...)
+	return kept, removed
+}
+
+func sessionNeedsPreview(session *Session) bool {
+	if len(session.Segments) == 0 {
+		return false
+	}
+	if session.PreviewStatus == PreviewProcessing {
+		return false
+	}
+	if session.PreviewStatus != PreviewReady || session.PreviewSegments < len(session.Segments) {
+		return true
+	}
+
+	previewUpdatedAt := parseSessionTime(session.PreviewUpdatedAt)
+	if previewUpdatedAt.IsZero() {
+		return true
+	}
+
+	for _, segment := range session.Segments {
+		uploadedAt := parseSessionTime(segment.UploadedAt)
+		if !uploadedAt.IsZero() && uploadedAt.After(previewUpdatedAt) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func (s *sessionStore) pruneExpiredRelaySessions(maxAge time.Duration, now time.Time) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	for id, session := range s.sessions {
+		if session.Purpose != PurposeRelay {
+			continue
+		}
+		lastActivity := parseSessionTime(session.UpdatedAt, session.LastStreamAt, session.LiveFrameUpdated, session.CreatedAt)
+		if lastActivity.IsZero() || now.Sub(lastActivity) < maxAge {
+			continue
+		}
+		delete(s.sessions, id)
+		delete(s.peers, id)
+		delete(s.viewerPeers, id)
+		delete(s.videoTracks, id)
+		if err := os.RemoveAll(s.sessionDir(id)); err != nil && !errors.Is(err, os.ErrNotExist) {
+			return err
+		}
+		if err := os.RemoveAll(s.publicDir(id)); err != nil && !errors.Is(err, os.ErrNotExist) {
+			return err
+		}
+	}
+
+	return nil
+}
+
 func (s *sessionStore) getSession(id string) (*Session, error) {
 	s.mu.RLock()
 	defer s.mu.RUnlock()
@@ -415,7 +536,7 @@ func (s *sessionStore) listProcessableSessions() []*Session {
 			items = append(items, cloneSession(session))
 			continue
 		}
-		if session.PreviewSegments < len(session.Segments) && session.PreviewStatus != PreviewProcessing {
+		if sessionNeedsPreview(session) {
 			items = append(items, cloneSession(session))
 		}
 	}
@@ -822,6 +943,7 @@ func (m *mediaServer) handleSegmentUpload(sessionID string, w http.ResponseWrite
 		return
 	}
 
+	removedSegments := []SegmentMeta{}
 	session, err := m.store.updateSession(sessionID, func(session *Session) error {
 		meta := SegmentMeta{
 			Sequence:    sequence,
@@ -842,9 +964,12 @@ func (m *mediaServer) handleSegmentUpload(sessionID string, w http.ResponseWrite
 		if !found {
 			session.Segments = append(session.Segments, meta)
 		}
-		sort.Slice(session.Segments, func(i, j int) bool {
+		sortSegmentsBySequence(session.Segments)
-			return session.Segments[i].Sequence < session.Segments[j].Sequence
+		if session.Purpose == PurposeRelay {
-		})
+			var kept []SegmentMeta
+			kept, removedSegments = trimSegmentsToDuration(session.Segments, relayPreviewWindow)
+			session.Segments = kept
+		}
 		session.Status = StatusRecording
 		session.LastError = ""
 		return nil
@@ -853,6 +978,12 @@ func (m *mediaServer) handleSegmentUpload(sessionID string, w http.ResponseWrite
 		writeError(w, http.StatusNotFound, err.Error())
 		return
 	}
+	for _, segment := range removedSegments {
+		segmentPath := filepath.Join(m.store.segmentsDir(sessionID), segment.Filename)
+		if removeErr := os.Remove(segmentPath); removeErr != nil && !errors.Is(removeErr, os.ErrNotExist) {
+			log.Printf("failed to remove pruned relay segment %s: %v", segmentPath, removeErr)
+		}
+	}
 	writeJSON(w, http.StatusAccepted, map[string]any{"session": session})
 }
 
@@ -919,6 +1050,9 @@ func runWorkerLoop(ctx context.Context, store *sessionStore, interval time.Durat
 				log.Printf("[worker] failed to refresh session store: %v", err)
 				continue
 			}
+			if err := store.pruneExpiredRelaySessions(relayCacheTTL, time.Now().UTC()); err != nil {
+				log.Printf("[worker] failed to prune relay cache: %v", err)
+			}
 			sessions := store.listProcessableSessions()
 			for _, session := range sessions {
 				if err := processSession(store, session.ID); err != nil {
@@ -939,7 +1073,7 @@ func processSession(store *sessionStore, sessionID string) error {
 		return processFinalArchive(store, sessionID)
 	}
 
-	if current.PreviewSegments < len(current.Segments) {
+	if sessionNeedsPreview(current) {
 		return processRollingPreview(store, sessionID)
 	}
 
@@ -1010,9 +1144,7 @@ func buildPlaybackArtifacts(store *sessionStore, session *Session, finalize bool
 	listFile := filepath.Join(store.sessionDir(sessionID), "concat.txt")
 
 	inputs := make([]string, 0, len(session.Segments))
-	sort.Slice(session.Segments, func(i, j int) bool {
+	sortSegmentsBySequence(session.Segments)
-		return session.Segments[i].Sequence < session.Segments[j].Sequence
-	})
 	for _, segment := range session.Segments {
 		inputs = append(inputs, filepath.Join(store.segmentsDir(sessionID), segment.Filename))
 	}
@@ -1038,10 +1170,12 @@ func buildPlaybackArtifacts(store *sessionStore, session *Session, finalize bool
 		}
 	}
 
+	if finalize {
 		mp4Err := runFFmpeg("-y", "-i", outputWebM, "-c:v", "libx264", "-preset", "veryfast", "-crf", "28", "-c:a", "aac", "-movflags", "+faststart", outputMP4)
 		if mp4Err != nil {
 			log.Printf("[worker] mp4 archive generation failed for %s: %v", sessionID, mp4Err)
 		}
+	}
 
 	webmInfo, webmStatErr := os.Stat(outputWebM)
 	if webmStatErr != nil {
@@ -1049,14 +1183,16 @@ func buildPlaybackArtifacts(store *sessionStore, session *Session, finalize bool
 	}
 	var mp4Size int64
 	var mp4URL string
+	previewURL := fmt.Sprintf("/media/assets/sessions/%s/%s.webm", sessionID, baseName)
+	if finalize {
 		if info, statErr := os.Stat(outputMP4); statErr == nil {
 			mp4Size = info.Size()
 			mp4URL = fmt.Sprintf("/media/assets/sessions/%s/recording.mp4", sessionID)
 		}
-	previewURL := fmt.Sprintf("/media/assets/sessions/%s/%s.webm", sessionID, baseName)
 		if mp4URL != "" {
 			previewURL = mp4URL
 		}
+	}
 
 	_, updateErr := store.updateSession(sessionID, func(session *Session) error {
 		session.Playback.PreviewURL = previewURL

media/main_test.go

@@ -2,12 +2,15 @@ package main
 
 import (
 	"encoding/json"
+	"errors"
 	"net/http"
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"testing"
+	"time"
 )
 
 func TestMediaHealthAndSessionLifecycle(t *testing.T) {
@@ -320,3 +323,130 @@ func TestLiveFrameUploadPublishesRelayFrame(t *testing.T) {
 		t.Fatalf("unexpected live frame content: %q", string(body))
 	}
 }
+
+func TestRelaySegmentUploadKeepsOnlyLatestMinute(t *testing.T) {
+	store, err := newSessionStore(t.TempDir())
+	if err != nil {
+		t.Fatalf("newSessionStore: %v", err)
+	}
+
+	server := newMediaServer(store)
+	session, err := store.createSession(CreateSessionRequest{UserID: "1", Title: "Relay Buffer", Purpose: "relay"})
+	if err != nil {
+		t.Fatalf("createSession: %v", err)
+	}
+
+	for sequence := 0; sequence < 3; sequence += 1 {
+		req := httptest.NewRequest(http.MethodPost, "/media/sessions/"+session.ID+"/segments?sequence="+strconv.Itoa(sequence)+"&durationMs=30000", strings.NewReader("segment"))
+		req.Header.Set("Content-Type", "video/webm")
+		res := httptest.NewRecorder()
+		server.routes().ServeHTTP(res, req)
+		if res.Code != http.StatusAccepted {
+			t.Fatalf("expected segment upload 202 for sequence %d, got %d", sequence, res.Code)
+		}
+	}
+
+	current, err := store.getSession(session.ID)
+	if err != nil {
+		t.Fatalf("getSession: %v", err)
+	}
+	if current.Purpose != PurposeRelay {
+		t.Fatalf("expected relay purpose, got %s", current.Purpose)
+	}
+	if len(current.Segments) != 2 {
+		t.Fatalf("expected latest 2 relay segments to remain, got %d", len(current.Segments))
+	}
+	if current.Segments[0].Sequence != 1 || current.Segments[1].Sequence != 2 {
+		t.Fatalf("expected relay segments 1 and 2 to remain, got %#v", current.Segments)
+	}
+	if _, err := os.Stat(filepath.Join(store.segmentsDir(session.ID), "000000.webm")); !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("expected earliest relay segment to be pruned from disk, got %v", err)
+	}
+}
+
+func TestProcessRelayPreviewPublishesBufferedWebM(t *testing.T) {
+	tempDir := t.TempDir()
+	store, err := newSessionStore(tempDir)
+	if err != nil {
+		t.Fatalf("newSessionStore: %v", err)
+	}
+
+	session, err := store.createSession(CreateSessionRequest{UserID: "1", Title: "Relay Preview", Purpose: "relay"})
+	if err != nil {
+		t.Fatalf("createSession: %v", err)
+	}
+
+	if err := os.WriteFile(filepath.Join(store.segmentsDir(session.ID), "000000.webm"), []byte("segment"), 0o644); err != nil {
+		t.Fatalf("write segment: %v", err)
+	}
+
+	if _, err := store.updateSession(session.ID, func(current *Session) error {
+		current.Segments = append(current.Segments, SegmentMeta{
+			Sequence:    0,
+			Filename:    "000000.webm",
+			DurationMS:  60000,
+			SizeBytes:   7,
+			ContentType: "video/webm",
+		})
+		current.Purpose = PurposeRelay
+		return nil
+	}); err != nil {
+		t.Fatalf("updateSession: %v", err)
+	}
+
+	if err := processRollingPreview(store, session.ID); err != nil {
+		t.Fatalf("processRollingPreview: %v", err)
+	}
+
+	current, err := store.getSession(session.ID)
+	if err != nil {
+		t.Fatalf("getSession: %v", err)
+	}
+	if current.Playback.PreviewURL == "" || !strings.HasSuffix(current.Playback.PreviewURL, "/preview.webm") {
+		t.Fatalf("expected relay preview webm url, got %#v", current.Playback)
+	}
+	if current.Playback.MP4URL != "" {
+		t.Fatalf("expected relay preview to skip mp4 generation, got %#v", current.Playback)
+	}
+}
+
+func TestPruneExpiredRelaySessionsRemovesOldCache(t *testing.T) {
+	store, err := newSessionStore(t.TempDir())
+	if err != nil {
+		t.Fatalf("newSessionStore: %v", err)
+	}
+
+	session, err := store.createSession(CreateSessionRequest{UserID: "1", Title: "Old Relay", Purpose: "relay"})
+	if err != nil {
+		t.Fatalf("createSession: %v", err)
+	}
+
+	if err := os.WriteFile(filepath.Join(store.segmentsDir(session.ID), "000000.webm"), []byte("segment"), 0o644); err != nil {
+		t.Fatalf("write segment: %v", err)
+	}
+	if err := os.MkdirAll(store.publicDir(session.ID), 0o755); err != nil {
+		t.Fatalf("mkdir public dir: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(store.publicDir(session.ID), "preview.webm"), []byte("preview"), 0o644); err != nil {
+		t.Fatalf("write preview: %v", err)
+	}
+
+	store.mu.Lock()
+	store.sessions[session.ID].Purpose = PurposeRelay
+	store.sessions[session.ID].UpdatedAt = time.Now().UTC().Add(-31 * time.Minute).Format(time.RFC3339)
+	store.mu.Unlock()
+
+	if err := store.pruneExpiredRelaySessions(relayCacheTTL, time.Now().UTC()); err != nil {
+		t.Fatalf("pruneExpiredRelaySessions: %v", err)
+	}
+
+	if _, err := store.getSession(session.ID); err == nil {
+		t.Fatalf("expected relay session to be removed from store")
+	}
+	if _, err := os.Stat(store.sessionDir(session.ID)); !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("expected relay session directory to be removed, got %v", err)
+	}
+	if _, err := os.Stat(store.publicDir(session.ID)); !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("expected relay public directory to be removed, got %v", err)
+	}
+}

tests/e2e/app.spec.ts

@@ -22,7 +22,9 @@ test("training page shows plan generation flow", async ({ page }) => {
 
   await page.goto("/training");
   await expect(page.getByTestId("training-title")).toBeVisible();
-  const generateButton = page.getByRole("button", { name: "生成训练计划" }).last();
+  const generateButton = page
+    .getByRole("button", { name: "生成训练计划" })
+    .last();
   await expect(generateButton).toBeVisible();
   await generateButton.click();
   await expect(page).toHaveURL(/\/training$/);
@@ -68,23 +70,40 @@ test("live camera starts analysis and produces scores", async ({ page }) => {
   await expect(page.getByTestId("live-camera-score-overall")).toBeVisible();
 });
 
-test("live camera switches into viewer mode when another device already owns analysis", async ({ page }) => {
+test("live camera switches into viewer mode when another device already owns analysis", async ({
+  page,
+}) => {
   await installAppMocks(page, { authenticated: true, liveViewerMode: true });
 
   await page.goto("/live-camera");
   await expect(page.getByText("同步观看模式")).toBeVisible();
   await expect(page.getByText(/同步观看|重新同步/).first()).toBeVisible();
   await expect(page.getByText("当前设备已锁定为观看模式")).toBeVisible();
-  await expect(page.getByTestId("live-camera-viewer-sync-card")).toContainText("其他设备实时分析");
+  await expect(page.getByTestId("live-camera-viewer-sync-card")).toContainText(
-  await expect(page.getByTestId("live-camera-viewer-sync-card")).toContainText("移动端");
+    "其他设备实时分析"
-  await expect(page.getByTestId("live-camera-viewer-sync-card")).toContainText("均衡模式");
+  );
-  await expect(page.getByTestId("live-camera-viewer-sync-card")).toContainText("猩猩");
+  await expect(page.getByTestId("live-camera-viewer-sync-card")).toContainText(
+    "移动端"
+  );
+  await expect(page.getByTestId("live-camera-viewer-sync-card")).toContainText(
+    "均衡模式"
+  );
+  await expect(page.getByTestId("live-camera-viewer-sync-card")).toContainText(
+    "猩猩"
+  );
   await expect(page.getByTestId("live-camera-score-overall")).toBeVisible();
 });
 
-test("live camera recovers mojibake viewer titles before rendering", async ({ page }) => {
+test("live camera recovers mojibake viewer titles before rendering", async ({
-  const state = await installAppMocks(page, { authenticated: true, liveViewerMode: true });
+  page,
-  const mojibakeTitle = Buffer.from("服务端同步烟雾测试", "utf8").toString("latin1");
+}) => {
+  const state = await installAppMocks(page, {
+    authenticated: true,
+    liveViewerMode: true,
+  });
+  const mojibakeTitle = Buffer.from("服务端同步烟雾测试", "utf8").toString(
+    "latin1"
+  );
   if (state.liveRuntime.runtimeSession) {
     state.liveRuntime.runtimeSession.title = mojibakeTitle;
     state.liveRuntime.runtimeSession.snapshot = {
@@ -94,11 +113,15 @@ test("live camera recovers mojibake viewer titles before rendering", async ({ pa
   }
 
   await page.goto("/live-camera");
-  await expect(page.getByRole("heading", { name: "服务端同步烟雾测试" })).toBeVisible();
+  await expect(
+    page.getByRole("heading", { name: "服务端同步烟雾测试" })
+  ).toBeVisible();
   await expect(page.getByText(mojibakeTitle)).toHaveCount(0);
 });
 
-test("live camera no longer opens viewer peer retries when server relay is active", async ({ page }) => {
+test("live camera no longer opens viewer peer retries when server relay is active", async ({
+  page,
+}) => {
   const state = await installAppMocks(page, {
     authenticated: true,
     liveViewerMode: true,
@@ -109,10 +132,12 @@ test("live camera no longer opens viewer peer retries when server relay is activ
   await expect(page.getByText("同步观看模式")).toBeVisible();
   await expect.poll(() => state.viewerSignalConflictRemaining).toBe(1);
   await expect.poll(() => state.mediaSession?.viewerCount ?? 0).toBe(0);
-  await expect(page.locator('img[alt="同步中的实时分析画面"]')).toBeVisible();
+  await expect(page.getByTestId("live-camera-viewer-video")).toBeVisible();
 });
 
-test("live camera archives overlay videos into the library after analysis stops", async ({ page }) => {
+test("live camera archives overlay videos into the library after analysis stops", async ({
+  page,
+}) => {
   await installAppMocks(page, { authenticated: true, videos: [] });
 
   await page.goto("/live-camera");
@@ -126,7 +151,9 @@ test("live camera archives overlay videos into the library after analysis stops"
   await expect(page.getByTestId("live-camera-score-overall")).toBeVisible();
 
   await page.getByRole("button", { name: "结束分析" }).click();
-  await expect(page.getByText("分析结果已保存")).toBeVisible({ timeout: 8_000 });
+  await expect(page.getByText("分析结果已保存")).toBeVisible({
+    timeout: 8_000,
+  });
 
   await page.goto("/videos");
   await expect(page.getByTestId("video-card")).toHaveCount(1);
@@ -134,7 +161,9 @@ test("live camera archives overlay videos into the library after analysis stops"
   await expect(page.getByText("实时分析").first()).toBeVisible();
 });
 
-test("recorder flow archives a session and exposes it in videos", async ({ page }) => {
+test("recorder flow archives a session and exposes it in videos", async ({
+  page,
+}) => {
   await installAppMocks(page, { authenticated: true, videos: [] });
 
   await page.setViewportSize({ width: 390, height: 844 });
@@ -145,7 +174,9 @@ test("recorder flow archives a session and exposes it in videos", async ({ page
   await expect(focusShell).toBeVisible();
 
   await focusShell.getByTestId("recorder-start-camera-button").click();
-  await expect(focusShell.getByTestId("recorder-start-recording-button")).toBeVisible();
+  await expect(
+    focusShell.getByTestId("recorder-start-recording-button")
+  ).toBeVisible();
 
   await focusShell.getByTestId("recorder-start-recording-button").click();
   await expect(focusShell.getByTestId("recorder-marker-button")).toBeVisible();
@@ -154,17 +185,23 @@ test("recorder flow archives a session and exposes it in videos", async ({ page
   await expect(page.getByText("手动标记")).toBeVisible();
 
   await focusShell.getByTestId("recorder-finish-button").click();
-  await expect(focusShell.getByTestId("recorder-reset-button")).toBeVisible({ timeout: 8_000 });
+  await expect(focusShell.getByTestId("recorder-reset-button")).toBeVisible({
+    timeout: 8_000,
+  });
 
   await page.goto("/videos");
   await expect(page.getByTestId("video-card")).toHaveCount(1);
   await expect(page.getByText("E2E 录制")).toBeVisible();
 });
 
-test("recorder blocks local camera when another device owns live analysis", async ({ page }) => {
+test("recorder blocks local camera when another device owns live analysis", async ({
+  page,
+}) => {
   await installAppMocks(page, { authenticated: true, liveViewerMode: true });
 
   await page.goto("/recorder");
-  await expect(page.getByText("当前账号已有其他设备正在实时分析")).toBeVisible();
+  await expect(
+    page.getByText("当前账号已有其他设备正在实时分析")
+  ).toBeVisible();
   await expect(page.getByTestId("recorder-start-camera-button")).toBeDisabled();
 });

tests/e2e/helpers/mockApp.ts

@@ -37,8 +37,10 @@ type MockMediaSession = {
   id: string;
   userId: string;
   title: string;
+  purpose?: "recording" | "relay";
   status: string;
   archiveStatus: string;
+  previewStatus?: string;
   format: string;
   mimeType: string;
   qualityPreset: string;
@@ -48,6 +50,7 @@ type MockMediaSession = {
   uploadedSegments: number;
   uploadedBytes: number;
   durationMs: number;
+  previewUpdatedAt?: string;
   streamConnected: boolean;
   viewerCount?: number;
   playback: {
@@ -255,34 +258,52 @@ async function readTrpcInput(route: Route, operationIndex: number) {
   if (!postData) return null;
 
   const parsed = JSON.parse(postData);
-  return parsed?.json ?? parsed?.[operationIndex]?.json ?? parsed?.[String(operationIndex)]?.json ?? null;
+  return (
+    parsed?.json ??
+    parsed?.[operationIndex]?.json ??
+    parsed?.[String(operationIndex)]?.json ??
+    null
+  );
 }
 
-function buildMediaSession(user: MockUser, title: string): MockMediaSession {
+function buildMediaSession(
+  user: MockUser,
+  title: string,
+  purpose: "recording" | "relay" = "recording"
+): MockMediaSession {
   return {
     id: "session-e2e",
     userId: String(user.id),
     title,
-    status: "created",
+    purpose,
+    status: purpose === "relay" ? "recording" : "created",
     archiveStatus: "idle",
+    previewStatus: purpose === "relay" ? "ready" : "idle",
     format: "webm",
     mimeType: "video/webm",
     qualityPreset: "balanced",
     facingMode: "environment",
     deviceKind: "mobile",
     reconnectCount: 0,
-    uploadedSegments: 0,
+    uploadedSegments: purpose === "relay" ? 1 : 0,
-    uploadedBytes: 0,
+    uploadedBytes: purpose === "relay" ? 1_280_000 : 0,
-    durationMs: 0,
+    durationMs: purpose === "relay" ? 60_000 : 0,
+    previewUpdatedAt: purpose === "relay" ? nowIso() : undefined,
     streamConnected: true,
     playback: {
-      ready: false,
+      ready: purpose !== "relay",
+      previewUrl:
+        purpose === "relay"
+          ? "/media/assets/sessions/session-e2e/preview.webm"
+          : undefined,
     },
     markers: [],
   };
 }
 
-function createTask(state: MockAppState, input: {
+function createTask(
+  state: MockAppState,
+  input: {
     type: string;
     title: string;
     status?: string;
@@ -290,7 +311,8 @@ function createTask(state: MockAppState, input: {
     message?: string;
     result?: any;
     error?: string | null;
-}) {
+  }
+) {
   const task = {
     id: `task-${state.nextTaskId++}`,
     userId: state.user.id,
@@ -304,7 +326,8 @@ function createTask(state: MockAppState, input: {
     attempts: input.status === "failed" ? 2 : 1,
     maxAttempts: input.type === "media_finalize" ? 90 : 3,
     startedAt: nowIso(),
-    completedAt: input.status === "queued" || input.status === "running" ? null : nowIso(),
+    completedAt:
+      input.status === "queued" || input.status === "running" ? null : nowIso(),
     createdAt: nowIso(),
     updatedAt: nowIso(),
   };
@@ -323,7 +346,8 @@ async function fulfillJson(route: Route, body: unknown) {
 async function handleTrpc(route: Route, state: MockAppState) {
   const url = new URL(route.request().url());
   const operations = url.pathname.replace("/api/trpc/", "").split(",");
-  const results = await Promise.all(operations.map(async (operation, operationIndex) => {
+  const results = await Promise.all(
+    operations.map(async (operation, operationIndex) => {
       switch (operation) {
         case "auth.me":
           if (state.authenticated && state.authMeNullResponsesAfterLogin > 0) {
@@ -437,7 +461,10 @@ async function handleTrpc(route: Route, state: MockAppState) {
         case "analysis.runtimeGet":
           return trpcResult(state.liveRuntime);
         case "analysis.runtimeAcquire":
-        if (state.liveRuntime.runtimeSession?.status === "active" && state.liveRuntime.role === "viewer") {
+          if (
+            state.liveRuntime.runtimeSession?.status === "active" &&
+            state.liveRuntime.role === "viewer"
+          ) {
             return trpcResult(state.liveRuntime);
           }
           state.liveRuntime = {
@@ -468,8 +495,11 @@ async function handleTrpc(route: Route, state: MockAppState) {
           if (state.liveRuntime.runtimeSession) {
             state.liveRuntime.runtimeSession = {
               ...state.liveRuntime.runtimeSession,
-            mediaSessionId: input?.mediaSessionId ?? state.liveRuntime.runtimeSession.mediaSessionId,
+              mediaSessionId:
-            snapshot: input?.snapshot ?? state.liveRuntime.runtimeSession.snapshot,
+                input?.mediaSessionId ??
+                state.liveRuntime.runtimeSession.mediaSessionId,
+              snapshot:
+                input?.snapshot ?? state.liveRuntime.runtimeSession.snapshot,
               lastHeartbeatAt: nowIso(),
             };
           }
@@ -485,14 +515,18 @@ async function handleTrpc(route: Route, state: MockAppState) {
         case "task.get": {
           const rawInput = url.searchParams.get("input");
           const parsedInput = rawInput ? JSON.parse(rawInput) : {};
-        const taskId = parsedInput.json?.taskId || parsedInput[0]?.json?.taskId;
+          const taskId =
-        return trpcResult(state.tasks.find((task) => task.id === taskId) || null);
+            parsedInput.json?.taskId || parsedInput[0]?.json?.taskId;
+          return trpcResult(
+            state.tasks.find(task => task.id === taskId) || null
+          );
         }
         case "task.retry": {
           const rawInput = url.searchParams.get("input");
           const parsedInput = rawInput ? JSON.parse(rawInput) : {};
-        const taskId = parsedInput.json?.taskId || parsedInput[0]?.json?.taskId;
+          const taskId =
-        const task = state.tasks.find((item) => item.id === taskId);
+            parsedInput.json?.taskId || parsedInput[0]?.json?.taskId;
+          const task = state.tasks.find(item => item.id === taskId);
           if (task) {
             task.status = "succeeded";
             task.progress = 100;
@@ -546,13 +580,15 @@ async function handleTrpc(route: Route, state: MockAppState) {
               type: "pose_correction_multimodal",
               title: "动作纠正",
               result: {
-              corrections: "## 动作概览\n整体节奏稳定，建议继续优化击球点前置。",
+                corrections:
+                  "## 动作概览\n整体节奏稳定，建议继续优化击球点前置。",
                 report: {
                   priorityFixes: [
                     {
                       title: "击球点前置",
                       why: "击球点略靠后会影响挥拍连贯性。",
-                    howToPractice: "每组 8 次影子挥拍，刻意在身体前侧完成触球动作。",
+                      howToPractice:
+                        "每组 8 次影子挥拍，刻意在身体前侧完成触球动作。",
                       successMetric: "连续 3 组都能稳定在身体前侧完成挥拍。",
                     },
                   ],
@@ -561,12 +597,17 @@ async function handleTrpc(route: Route, state: MockAppState) {
             }).id,
           });
         case "video.registerExternal":
-        if (state.mediaSession?.playback.webmUrl || state.mediaSession?.playback.mp4Url) {
+          if (
+            state.mediaSession?.playback.webmUrl ||
+            state.mediaSession?.playback.mp4Url
+          ) {
             state.videos = [
               {
                 id: state.nextVideoId++,
                 title: state.mediaSession.title,
-              url: state.mediaSession.playback.webmUrl || state.mediaSession.playback.mp4Url,
+                url:
+                  state.mediaSession.playback.webmUrl ||
+                  state.mediaSession.playback.mp4Url,
                 format: "webm",
                 fileSize: state.mediaSession.playback.webmSize || 1024 * 1024,
                 exerciseType: "recording",
@@ -576,7 +617,10 @@ async function handleTrpc(route: Route, state: MockAppState) {
               ...state.videos,
             ];
           }
-        return trpcResult({ videoId: state.nextVideoId, url: state.mediaSession?.playback.webmUrl });
+          return trpcResult({
+            videoId: state.nextVideoId,
+            url: state.mediaSession?.playback.webmUrl,
+          });
         case "achievement.list":
           return trpcResult(buildStats(state.user).achievements);
         case "rating.current":
@@ -599,21 +643,35 @@ async function handleTrpc(route: Route, state: MockAppState) {
                 timing: 68,
                 matchReadiness: 60,
               },
-            sourceSummary: { analyses: 1, liveSessions: 0, totalEffectiveActions: 12, totalPk: 0, activeDays: 1 },
+              sourceSummary: {
+                analyses: 1,
+                liveSessions: 0,
+                totalEffectiveActions: 12,
+                totalPk: 0,
+                activeDays: 1,
+              },
             },
             {
               id: 2,
               rating: state.user.ntrpRating,
               triggerType: "daily",
               createdAt: nowIso(),
-            dimensionScores: buildStats(state.user).latestNtrpSnapshot.dimensionScores,
+              dimensionScores: buildStats(state.user).latestNtrpSnapshot
-            sourceSummary: { analyses: 2, liveSessions: 1, totalEffectiveActions: 36, totalPk: 0, activeDays: 2 },
+                .dimensionScores,
+              sourceSummary: {
+                analyses: 2,
+                liveSessions: 1,
+                totalEffectiveActions: 36,
+                totalPk: 0,
+                activeDays: 2,
+              },
             },
           ]);
         default:
           return trpcResult(null);
       }
-  }));
+    })
+  );
 
   await fulfillJson(route, results);
 }
@@ -649,7 +707,11 @@ async function handleMedia(route: Route, state: MockAppState) {
       return;
     }
     state.mediaSession.viewerCount = (state.mediaSession.viewerCount || 0) + 1;
-    await fulfillJson(route, { viewerId: `viewer-${state.mediaSession.viewerCount}`, type: "answer", sdp: "mock-answer" });
+    await fulfillJson(route, {
+      viewerId: `viewer-${state.mediaSession.viewerCount}`,
+      type: "answer",
+      sdp: "mock-answer",
+    });
     return;
   }
 
@@ -689,6 +751,16 @@ async function handleMedia(route: Route, state: MockAppState) {
   }
 
   if (path === `/media/sessions/${state.mediaSession.id}`) {
+    if (state.mediaSession.purpose === "relay") {
+      state.mediaSession.previewStatus = "ready";
+      state.mediaSession.previewUpdatedAt = nowIso();
+      state.mediaSession.playback = {
+        ready: true,
+        webmUrl: "/media/assets/sessions/session-e2e/preview.webm",
+        webmSize: 1_800_000,
+        previewUrl: "/media/assets/sessions/session-e2e/preview.webm",
+      };
+    } else {
       state.mediaSession.status = "archived";
       state.mediaSession.archiveStatus = "completed";
       state.mediaSession.playback = {
@@ -699,6 +771,7 @@ async function handleMedia(route: Route, state: MockAppState) {
         mp4Size: 1_800_000,
         previewUrl: "/media/assets/sessions/session-e2e/recording.webm",
       };
+    }
     await fulfillJson(route, { session: state.mediaSession });
     return;
   }
@@ -727,7 +800,13 @@ export async function installAppMocks(
     viewerSignalConflictOnce?: boolean;
   }
 ) {
-  const seededViewerSession = options?.liveViewerMode ? buildMediaSession(buildUser(options?.userName), "其他设备实时分析") : null;
+  const seededViewerSession = options?.liveViewerMode
+    ? buildMediaSession(
+        buildUser(options?.userName),
+        "其他设备实时分析",
+        "relay"
+      )
+    : null;
   const state: MockAppState = {
     authenticated: options?.authenticated ?? false,
     user: buildUser(options?.userName),
@@ -940,7 +1019,11 @@ export async function installAppMocks(
 
       setOptions() {}
 
-      onResults(callback: (results: { poseLandmarks: ReturnType<typeof buildFakeLandmarks> }) => void) {
+      onResults(
+        callback: (results: {
+          poseLandmarks: ReturnType<typeof buildFakeLandmarks>;
+        }) => void
+      ) {
         this.callback = callback;
       }
 
@@ -964,10 +1047,14 @@ export async function installAppMocks(
     Object.defineProperty(HTMLMediaElement.prototype, "srcObject", {
       configurable: true,
       get() {
-        return (this as HTMLMediaElement & { __srcObject?: MediaStream }).__srcObject ?? null;
+        return (
+          (this as HTMLMediaElement & { __srcObject?: MediaStream })
+            .__srcObject ?? null
+        );
       },
       set(value) {
-        (this as HTMLMediaElement & { __srcObject?: MediaStream }).__srcObject = value as MediaStream;
+        (this as HTMLMediaElement & { __srcObject?: MediaStream }).__srcObject =
+          value as MediaStream;
       },
     });
 
@@ -997,7 +1084,11 @@ export async function installAppMocks(
         if (this.state !== "recording") return;
         const event = new Event("dataavailable") as Event & { data?: Blob };
         event.data = new Blob(["segment"], { type: this.mimeType });
-        const handler = (this as unknown as { ondataavailable?: (evt: Event & { data?: Blob }) => void }).ondataavailable;
+        const handler = (
+          this as unknown as {
+            ondataavailable?: (evt: Event & { data?: Blob }) => void;
+          }
+        ).ondataavailable;
         handler?.(event);
         this.dispatchEvent(event);
       }
@@ -1061,10 +1152,21 @@ export async function installAppMocks(
     Object.defineProperty(navigator, "mediaDevices", {
       configurable: true,
       value: {
-        getUserMedia: async (constraints?: { audio?: unknown }) => createFakeMediaStream(Boolean(constraints?.audio)),
+        getUserMedia: async (constraints?: { audio?: unknown }) =>
+          createFakeMediaStream(Boolean(constraints?.audio)),
         enumerateDevices: async () => [
-          { deviceId: "cam-1", kind: "videoinput", label: "Front Camera", groupId: "g1" },
+          {
-          { deviceId: "cam-2", kind: "videoinput", label: "Back Camera", groupId: "g1" },
+            deviceId: "cam-1",
+            kind: "videoinput",
+            label: "Front Camera",
+            groupId: "g1",
+          },
+          {
+            deviceId: "cam-2",
+            kind: "videoinput",
+            label: "Back Camera",
+            groupId: "g1",
+          },
         ],
         addEventListener: () => undefined,
         removeEventListener: () => undefined,
@@ -1072,8 +1174,8 @@ export async function installAppMocks(
     });
   });
 
-  await page.route("**/api/trpc/**", (route) => handleTrpc(route, state));
+  await page.route("**/api/trpc/**", route => handleTrpc(route, state));
-  await page.route("**/media/**", (route) => handleMedia(route, state));
+  await page.route("**/media/**", route => handleMedia(route, state));
 
   return state;
 }