feat: integrate pixel teacher presence and resilient classroom preview

src/pages/Chat/CodingRecoveryCard.tsx

@@ -0,0 +1,32 @@
+import { useRef, useState } from 'react';
+import { Button } from '@/components/ui/button';
+import { normalizeAppError } from '@/lib/error-model';
+import { codingRecovery, type CodingRecoveryAction } from '../../../shared/coding-recovery';
+
+export function CodingRecoveryCard({ code, work, onRecovery }: {
+  code?: string;
+  work: boolean;
+  onRecovery(action: CodingRecoveryAction, work: boolean): Promise<void> | void;
+}) {
+  const [busy, setBusy] = useState(false);
+  const [retryCode, setRetryCode] = useState<string>();
+  const [retryFailed, setRetryFailed] = useState(false);
+  const flight = useRef(false);
+  const recovery = codingRecovery(retryCode ?? code, work);
+  return <div role="status" className="rounded-xl border border-brand/15 bg-brand/5 p-4 text-sm" data-testid="coding-recovery-card">
+    <p className="font-medium">{work ? '作品还没有打开' : '这一步需要再接着做'}</p>
+    <p className="mt-1 text-muted-foreground">{retryFailed ? '暂时还没连接上。可以稍后再试，已输入的内容会保留。' : recovery.message}</p>
+    <Button className="mt-3" size="sm" variant="outline" disabled={busy} onClick={async () => {
+      if (flight.current) return;
+      flight.current = true;
+      setBusy(true);
+      setRetryFailed(false);
+      try { await onRecovery(recovery.action, work); }
+      catch (error) {
+        const failure = normalizeAppError(error);
+        setRetryCode(typeof failure.details?.backendCode === 'string' ? failure.details.backendCode : failure.code);
+        setRetryFailed(failure.code !== 'AUTH_INVALID');
+      } finally { flight.current = false; setBusy(false); }
+    }}>{busy ? '正在接着处理…' : recovery.label}</Button>
+  </div>;
+}