fix(chat): 发送后切会话不再误标未读，管理端撤回实时同步到对话页

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/lib/linkify.ts

@@ -0,0 +1,55 @@
+/**
+ * 纯文本 URL 切分（QQ 风格：识别 http(s):// 与 www.）
+ * 仅产出 http/https，拒绝其它协议。
+ */
+
+const URL_RE = /(?:https?:\/\/|www\.)[^\s\u4e00-\u9fff<>"'`]+/gi;
+
+/** 常见尾随标点从 URL 剥离（中英） */
+const TRAIL_PUNCT = /[.,;:!?。，；：！？、)\]}》〉』」"'`]+$/;
+
+export type LinkifyPart =
+  | { type: "text"; value: string }
+  | { type: "url"; value: string; href: string };
+
+function toHref(raw: string): string | null {
+  const href = /^www\./i.test(raw) ? `https://${raw}` : raw;
+  try {
+    const u = new URL(href);
+    if (u.protocol !== "http:" && u.protocol !== "https:") return null;
+    return u.href;
+  } catch {
+    return null;
+  }
+}
+
+function peel(raw: string): { core: string; trail: string } {
+  const m = raw.match(TRAIL_PUNCT);
+  if (!m) return { core: raw, trail: "" };
+  return { core: raw.slice(0, -m[0].length), trail: m[0] };
+}
+
+/** 将纯文本切成文本段与可安全打开的链接段 */
+export function linkifyParts(text: string): LinkifyPart[] {
+  if (!text) return [];
+  const parts: LinkifyPart[] = [];
+  let last = 0;
+  URL_RE.lastIndex = 0;
+  let m: RegExpExecArray | null;
+  while ((m = URL_RE.exec(text)) !== null) {
+    if (m.index > last) {
+      parts.push({ type: "text", value: text.slice(last, m.index) });
+    }
+    const { core, trail } = peel(m[0]);
+    const href = core ? toHref(core) : null;
+    if (href && core) {
+      parts.push({ type: "url", value: core, href });
+      if (trail) parts.push({ type: "text", value: trail });
+    } else {
+      parts.push({ type: "text", value: m[0] });
+    }
+    last = m.index + m[0].length;
+  }
+  if (last < text.length) parts.push({ type: "text", value: text.slice(last) });
+  return parts.length ? parts : [{ type: "text", value: text }];
+}