feat: render link metadata cards

web/src/components/MemoContent/LinkMetadataCard.tsx

@@ -0,0 +1,70 @@
+import type React from "react";
+import { useEffect, useState } from "react";
+import { useLinkMetadata } from "@/hooks/useMemoQueries";
+import { cn } from "@/lib/utils";
+
+interface LinkMetadataCardProps {
+  url: string;
+  fallback: React.ReactNode;
+}
+
+function getHostname(url: string): string {
+  try {
+    return new URL(url).hostname.replace(/^www\./, "");
+  } catch {
+    return "";
+  }
+}
+
+const LinkMetadataCard = ({ url, fallback }: LinkMetadataCardProps) => {
+  const [imageFailed, setImageFailed] = useState(false);
+  const { data: metadata, isSuccess } = useLinkMetadata(url);
+
+  const title = metadata?.title.trim() ?? "";
+  const description = metadata?.description.trim() ?? "";
+  const image = metadata?.image.trim() ?? "";
+  const hostname = getHostname(metadata?.url || url);
+  const hasUsefulMetadata = title !== "" || description !== "";
+
+  useEffect(() => {
+    setImageFailed(false);
+  }, [url, image]);
+
+  if (!isSuccess || !hasUsefulMetadata) {
+    return fallback;
+  }
+
+  return (
+    <a
+      href={url}
+      target="_blank"
+      rel="noopener noreferrer"
+      className={cn(
+        "group my-0 mb-2 flex w-full max-w-full overflow-hidden rounded-md border border-border bg-muted/20 text-foreground no-underline transition-colors",
+        "hover:border-primary/35 hover:bg-accent/20",
+      )}
+    >
+      <span className="flex min-w-0 flex-1 flex-col gap-0.5 px-2.5 py-2 sm:gap-1 sm:px-3 sm:py-2.5">
+        {hostname && <span className="truncate text-[11px] leading-4 text-muted-foreground sm:text-xs">{hostname}</span>}
+        {title && <span className="line-clamp-2 text-sm font-medium leading-5 text-foreground">{title}</span>}
+        {description && <span className="line-clamp-1 text-xs leading-4 text-muted-foreground sm:line-clamp-2">{description}</span>}
+      </span>
+      {image && !imageFailed && (
+        <span className="flex w-24 shrink-0 items-center border-l border-border/70 bg-muted/40 sm:w-40">
+          <span className="aspect-[1.91/1] w-full overflow-hidden">
+            <img
+              src={image}
+              alt=""
+              className="h-full w-full object-cover transition-transform duration-200 group-hover:scale-[1.01]"
+              loading="lazy"
+              decoding="async"
+              onError={() => setImageFailed(true)}
+            />
+          </span>
+        </span>
+      )}
+    </a>
+  );
+};
+
+export default LinkMetadataCard;

web/src/components/MemoContent/MarkdownRenderContext.tsx

@@ -0,0 +1,22 @@
+import { createContext, useContext, useMemo } from "react";
+
+interface MarkdownRenderContextValue {
+  blockDepth: number;
+}
+
+export const rootMarkdownRenderContext: MarkdownRenderContextValue = {
+  blockDepth: 0,
+};
+
+export const MarkdownRenderContext = createContext<MarkdownRenderContextValue>(rootMarkdownRenderContext);
+
+export const useMarkdownRenderContext = () => {
+  return useContext(MarkdownRenderContext);
+};
+
+export const NestedMarkdownRenderContext = ({ children }: { children: React.ReactNode }) => {
+  const { blockDepth } = useMarkdownRenderContext();
+  const value = useMemo<MarkdownRenderContextValue>(() => ({ blockDepth: blockDepth + 1 }), [blockDepth]);
+
+  return <MarkdownRenderContext.Provider value={value}>{children}</MarkdownRenderContext.Provider>;
+};

web/src/components/MemoContent/MemoMarkdownRenderer.tsx

@@ -16,6 +16,7 @@ import { remarkSplitMixedTaskLists } from "@/utils/remark-plugins/remark-split-m
 import { remarkTag } from "@/utils/remark-plugins/remark-tag";
 import { CodeBlock } from "./CodeBlock";
 import { SANITIZE_SCHEMA } from "./constants";
+import { MarkdownRenderContext, rootMarkdownRenderContext } from "./MarkdownRenderContext";
 import { Mention } from "./Mention";
 import { Blockquote, Heading, HorizontalRule, Image, InlineCode, Link, List, ListItem, Paragraph } from "./markdown";
 import { Table, TableBody, TableCell, TableHead, TableHeaderCell, TableRow } from "./Table";
@@ -119,21 +120,28 @@ export const MemoMarkdownRenderer = ({ content, resolvedMentionUsernames }: Memo
   };
 
   return (
-    <ReactMarkdown
-      remarkPlugins={[
-        remarkDisableSetext,
-        remarkMath,
-        remarkGfm,
-        remarkSplitMixedTaskLists,
-        remarkBreaks,
-        remarkMention,
-        remarkTag,
-        remarkPreserveType,
-      ]}
-      rehypePlugins={[rehypeRaw, [rehypeSanitize, SANITIZE_SCHEMA], rehypeHeadingId, [rehypeKatex, { throwOnError: false, strict: false }]]}
-      components={markdownComponents}
-    >
-      {content}
-    </ReactMarkdown>
+    <MarkdownRenderContext.Provider value={rootMarkdownRenderContext}>
+      <ReactMarkdown
+        remarkPlugins={[
+          remarkDisableSetext,
+          remarkMath,
+          remarkGfm,
+          remarkSplitMixedTaskLists,
+          remarkBreaks,
+          remarkMention,
+          remarkTag,
+          remarkPreserveType,
+        ]}
+        rehypePlugins={[
+          rehypeRaw,
+          [rehypeSanitize, SANITIZE_SCHEMA],
+          rehypeHeadingId,
+          [rehypeKatex, { throwOnError: false, strict: false }],
+        ]}
+        components={markdownComponents}
+      >
+        {content}
+      </ReactMarkdown>
+    </MarkdownRenderContext.Provider>
   );
 };

web/src/components/MemoContent/Table.tsx

@@ -1,4 +1,5 @@
 import { cn } from "@/lib/utils";
+import { NestedMarkdownRenderContext } from "./MarkdownRenderContext";
 import type { ReactMarkdownProps } from "./markdown/types";
 
 interface TableProps extends React.HTMLAttributes<HTMLTableElement>, ReactMarkdownProps {
@@ -58,7 +59,7 @@ interface TableHeaderCellProps extends React.ThHTMLAttributes<HTMLTableCellEleme
 export const TableHeaderCell = ({ children, className, node: _node, ...props }: TableHeaderCellProps) => {
   return (
     <th className={cn("px-2 py-1 text-left align-middle text-sm font-medium text-muted-foreground", className)} {...props}>
-      {children}
+      <NestedMarkdownRenderContext>{children}</NestedMarkdownRenderContext>
     </th>
   );
 };
@@ -70,7 +71,7 @@ interface TableCellProps extends React.TdHTMLAttributes<HTMLTableCellElement>, R
 export const TableCell = ({ children, className, node: _node, ...props }: TableCellProps) => {
   return (
     <td className={cn("px-2 py-1 text-left align-middle text-sm", className)} {...props}>
-      {children}
+      <NestedMarkdownRenderContext>{children}</NestedMarkdownRenderContext>
     </td>
   );
 };

web/src/components/MemoContent/markdown/Blockquote.tsx

@@ -1,4 +1,5 @@
 import { cn } from "@/lib/utils";
+import { NestedMarkdownRenderContext } from "../MarkdownRenderContext";
 import type { ReactMarkdownProps } from "./types";
 
 interface BlockquoteProps extends React.BlockquoteHTMLAttributes<HTMLQuoteElement>, ReactMarkdownProps {
@@ -11,7 +12,7 @@ interface BlockquoteProps extends React.BlockquoteHTMLAttributes<HTMLQuoteElemen
 export const Blockquote = ({ children, className, node: _node, ...props }: BlockquoteProps) => {
   return (
     <blockquote className={cn("my-0 mb-2 border-l-4 border-primary/30 pl-3 text-muted-foreground italic", className)} {...props}>
-      {children}
+      <NestedMarkdownRenderContext>{children}</NestedMarkdownRenderContext>
     </blockquote>
   );
 };

web/src/components/MemoContent/markdown/List.tsx

@@ -1,5 +1,6 @@
 import { cn } from "@/lib/utils";
 import { TASK_LIST_CLASS, TASK_LIST_ITEM_CLASS } from "../constants";
+import { NestedMarkdownRenderContext } from "../MarkdownRenderContext";
 import type { ReactMarkdownProps } from "./types";
 
 interface ListProps extends React.HTMLAttributes<HTMLUListElement | HTMLOListElement>, ReactMarkdownProps {
@@ -55,14 +56,14 @@ export const ListItem = ({ children, className, node: _node, ...domProps }: List
         )}
         {...domProps}
       >
-        {children}
+        <NestedMarkdownRenderContext>{children}</NestedMarkdownRenderContext>
       </li>
     );
   }
 
   return (
     <li className={cn("mt-0.5 leading-6", className)} {...domProps}>
-      {children}
+      <NestedMarkdownRenderContext>{children}</NestedMarkdownRenderContext>
     </li>
   );
 };

web/src/components/MemoContent/markdown/Paragraph.tsx

@@ -1,17 +1,47 @@
+import type { Element } from "hast";
 import { cn } from "@/lib/utils";
+import LinkMetadataCard from "../LinkMetadataCard";
+import { useMarkdownRenderContext } from "../MarkdownRenderContext";
 import type { ReactMarkdownProps } from "./types";
 
 interface ParagraphProps extends React.HTMLAttributes<HTMLParagraphElement>, ReactMarkdownProps {
   children: React.ReactNode;
 }
 
-/**
- * Paragraph component with compact spacing
- */
-export const Paragraph = ({ children, className, node: _node, ...props }: ParagraphProps) => {
-  return (
+function getSingleLinkHref(node?: Element): string | undefined {
+  if (!node || node.tagName !== "p") {
+    return undefined;
+  }
+
+  const meaningfulChildren = node.children.filter((child) => {
+    return !(child.type === "text" && child.value.trim() === "");
+  });
+
+  if (meaningfulChildren.length !== 1) {
+    return undefined;
+  }
+
+  const onlyChild = meaningfulChildren[0];
+  if (onlyChild.type !== "element" || onlyChild.tagName !== "a") {
+    return undefined;
+  }
+
+  const href = onlyChild.properties?.href;
+  return typeof href === "string" ? href : undefined;
+}
+
+export const Paragraph = ({ children, className, node, ...props }: ParagraphProps) => {
+  const { blockDepth } = useMarkdownRenderContext();
+  const href = blockDepth === 0 ? getSingleLinkHref(node) : undefined;
+  const paragraph = (
     <p className={cn("my-0 mb-2 leading-6", className)} {...props}>
       {children}
     </p>
   );
+
+  if (href) {
+    return <LinkMetadataCard url={href} fallback={paragraph} />;
+  }
+
+  return paragraph;
 };

web/src/hooks/useMemoQueries.ts

@@ -15,6 +15,7 @@ export const memoKeys = {
   details: () => [...memoKeys.all, "detail"] as const,
   detail: (name: string) => [...memoKeys.details(), name] as const,
   comments: (name: string) => [...memoKeys.all, "comments", name] as const,
+  linkMetadata: (url: string) => [...memoKeys.all, "linkMetadata", url] as const,
 };
 
 type MemoPatch = Partial<Memo> & Pick<Memo, "name">;
@@ -149,6 +150,30 @@ export function useMemo(name: string, options?: { enabled?: boolean }) {
   });
 }
 
+function isHTTPURL(url: string): boolean {
+  try {
+    const parsed = new URL(url);
+    return parsed.protocol === "http:" || parsed.protocol === "https:";
+  } catch {
+    return false;
+  }
+}
+
+export function useLinkMetadata(url: string, options?: { enabled?: boolean }) {
+  const trimmedUrl = url.trim();
+
+  return useQuery({
+    queryKey: memoKeys.linkMetadata(trimmedUrl),
+    queryFn: async () => {
+      const metadata = await memoServiceClient.getLinkMetadata({ url: trimmedUrl });
+      return metadata;
+    },
+    enabled: (options?.enabled ?? true) && isHTTPURL(trimmedUrl),
+    staleTime: 1000 * 60 * 60 * 24,
+    gcTime: 1000 * 60 * 60 * 24,
+  });
+}
+
 export function useCreateMemo() {
   const queryClient = useQueryClient();