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/components/AutolinkText.tsx

@@ -0,0 +1,62 @@
+"use client";
+
+import type { ReactNode } from "react";
+import { usePostLinkNewTab } from "@/components/PostLinkProvider";
+import { linkifyParts } from "@/lib/linkify";
+
+function AutolinkAnchor({
+  href,
+  children,
+  openInNewTab,
+}: {
+  href: string;
+  children: ReactNode;
+  openInNewTab: boolean;
+}) {
+  return (
+    <a
+      href={href}
+      className="j13-autolink break-all"
+      style={{ color: "var(--accent)", textDecoration: "underline" }}
+      {...(openInNewTab ? { target: "_blank", rel: "noopener noreferrer" } : {})}
+      onClick={(e) => e.stopPropagation()}
+      onContextMenu={(e) => e.stopPropagation()}
+    >
+      {children}
+    </a>
+  );
+}
+
+/**
+ * 纯文本自动识别 URL。
+ * forceNewTab：聊天等场景始终新开；否则读 PostLinkProvider（post_link_new_tab）。
+ */
+export default function AutolinkText({
+  text,
+  renderText,
+  forceNewTab = false,
+}: {
+  text: string;
+  renderText?: (segment: string) => ReactNode;
+  forceNewTab?: boolean;
+}) {
+  const settingNewTab = usePostLinkNewTab();
+  const openInNewTab = forceNewTab || settingNewTab;
+  const parts = linkifyParts(text);
+  return (
+    <>
+      {parts.map((p, i) => {
+        const key = `l-${i}`;
+        if (p.type === "url") {
+          return (
+            <AutolinkAnchor key={key} href={p.href} openInNewTab={openInNewTab}>
+              {p.value}
+            </AutolinkAnchor>
+          );
+        }
+        if (renderText) return <span key={key}>{renderText(p.value)}</span>;
+        return <span key={key}>{p.value}</span>;
+      })}
+    </>
+  );
+}

frontend/components/PostLinkProvider.tsx

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+"use client";
+
+import { createContext, useContext } from "react";
+
+const PostLinkCtx = createContext(true);
+
+/** 帖内 Markdown 外链是否新标签打开（来自公开站点设置） */
+export default function PostLinkProvider({
+  openInNewTab,
+  children,
+}: {
+  openInNewTab: boolean;
+  children: React.ReactNode;
+}) {
+  return <PostLinkCtx.Provider value={openInNewTab}>{children}</PostLinkCtx.Provider>;
+}
+
+export function usePostLinkNewTab() {
+  return useContext(PostLinkCtx);
+}