直播观众：negotiate 失败后恢复轮询；防并发 poll；长时 502 提示

Made-with: Cursor

web/src/utils/liveWebRTC.js

@@ -47,6 +47,8 @@ export function startViewing(videoEl, opts = {}) {
   let ws = null
   let pollTimer = null
   let currentPollMs = pollMs
+  let pollInFlight = false
+  let upstreamErrorStreak = 0
   let stopped = false
   let blackFrameTimer = null
 
@@ -109,8 +111,12 @@ export function startViewing(videoEl, opts = {}) {
     if (pollTimer) return
     rebuildPeer()
     currentPollMs = pollMs
+    upstreamErrorStreak = 0
     schedulePollLoop()
-    poll()
+    // 下一轮再 poll，避免从 poll() 内同步调用时 pollInFlight 仍为 true 导致被跳过
+    setTimeout(() => {
+      if (!stopped) poll()
+    }, 0)
   }
 
   async function negotiate() {
@@ -173,10 +179,17 @@ export function startViewing(videoEl, opts = {}) {
 
   async function poll() {
     if (stopped) return
+    if (pollInFlight) return
+    pollInFlight = true
     try {
       const { live, upstreamError } = await fetchLiveStatus()
       if (upstreamError) {
-        onStatus('无法连接服务器（网关 502/离线），将放慢重试…')
+        upstreamErrorStreak += 1
+        const extra =
+          upstreamErrorStreak >= 6
+            ? ' 若长时间如此，多为服务端未启动或网关异常，请刷新页面或联系管理员。'
+            : ''
+        onStatus(`无法连接服务器（网关 502/离线），将放慢重试…${extra}`)
         const next = Math.min(Math.round(currentPollMs * 1.5), 30000)
         if (next !== currentPollMs) {
           currentPollMs = next
@@ -184,6 +197,7 @@ export function startViewing(videoEl, opts = {}) {
         }
         return
       }
+      upstreamErrorStreak = 0
       if (currentPollMs !== pollMs) {
         currentPollMs = pollMs
         schedulePollLoop()
@@ -195,12 +209,23 @@ export function startViewing(videoEl, opts = {}) {
         }
         onLive()
         onStatus('检测到直播，正在连接…')
+        try {
           await negotiate()
+        } catch (err) {
+          onStatus(
+            err?.message
+              ? `拉流连接失败：${err.message}`
+              : '拉流连接失败，将恢复轮询…'
+          )
+          resumePollingAfterDisconnect('')
+        }
         return
       }
       onStatus('等待主播开播…')
     } catch {
       onStatus('无法获取直播状态')
+    } finally {
+      pollInFlight = false
     }
   }