feat: add inline citations and thread management features

Citations:
- Add citations parsing utilities for extracting source references from AI responses
- Render inline citations as hover card badges in message content
- Display citation cards with title, URL, and description on hover
- Add citation badge rendering in artifact markdown preview
- Update prompt to guide AI to output citations in correct format

Thread Management:
- Add rename functionality for chat threads with dialog UI
- Add share functionality to copy thread link to clipboard
- Share links use Vercel URL for production accessibility
- Add useRenameThread hook for thread title updates

i18n:
- Add translations for rename, share, cancel, save, and linkCopied

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

frontend/src/components/workspace/messages/message-list-item.tsx

@@ -1,14 +1,28 @@
 import type { Message } from "@langchain/langgraph-sdk";
+import { ExternalLinkIcon, LinkIcon } from "lucide-react";
 import { useParams } from "next/navigation";
 import { memo, useMemo } from "react";
 
+import {
+  InlineCitationCard,
+  InlineCitationCardBody,
+  InlineCitationSource,
+} from "@/components/ai-elements/inline-citation";
 import {
   Message as AIElementMessage,
   MessageContent as AIElementMessageContent,
   MessageResponse as AIElementMessageResponse,
   MessageToolbar,
 } from "@/components/ai-elements/message";
+import { Badge } from "@/components/ui/badge";
+import { HoverCardTrigger } from "@/components/ui/hover-card";
 import { resolveArtifactURL } from "@/core/artifacts/utils";
+import {
+  type Citation,
+  buildCitationMap,
+  extractDomainFromUrl,
+  parseCitations,
+} from "@/core/citations";
 import {
   extractContentFromMessage,
   extractReasoningContentFromMessage,
@@ -68,20 +82,63 @@ function MessageContent_({
   isLoading?: boolean;
 }) {
   const rehypePlugins = useRehypeSplitWordsIntoSpans(isLoading);
-  const content = useMemo(() => {
+
+  // Extract and parse citations from message content
+  const { citations, cleanContent } = useMemo(() => {
     const reasoningContent = extractReasoningContentFromMessage(message);
-    const content = extractContentFromMessage(message);
-    if (!isLoading && reasoningContent && !content) {
-      return reasoningContent;
+    const rawContent = extractContentFromMessage(message);
+    if (!isLoading && reasoningContent && !rawContent) {
+      return { citations: [], cleanContent: reasoningContent };
     }
-    return content;
+    return parseCitations(rawContent ?? "");
   }, [isLoading, message]);
+
+  // Build citation map for quick URL lookup
+  const citationMap = useMemo(
+    () => buildCitationMap(citations),
+    [citations],
+  );
+
   const { thread_id } = useParams<{ thread_id: string }>();
+
   return (
     <AIElementMessageContent className={className}>
+      {/* Citations list at the top */}
+      {citations.length > 0 && <CitationsList citations={citations} />}
+
       <AIElementMessageResponse
         rehypePlugins={rehypePlugins}
         components={{
+          a: ({
+            href,
+            children,
+          }: React.AnchorHTMLAttributes<HTMLAnchorElement>) => {
+            if (!href) {
+              return <span>{children}</span>;
+            }
+
+            // Check if this link matches a citation
+            const citation = citationMap.get(href);
+            if (citation) {
+              return (
+                <CitationLink citation={citation} href={href}>
+                  {children}
+                </CitationLink>
+              );
+            }
+
+            // Regular external link
+            return (
+              <a
+                href={href}
+                target="_blank"
+                rel="noopener noreferrer"
+                className="text-primary underline underline-offset-2 hover:no-underline"
+              >
+                {children}
+              </a>
+            );
+          },
           img: ({ src, alt }: React.ImgHTMLAttributes<HTMLImageElement>) => {
             if (!src) return null;
             if (typeof src !== "string") {
@@ -109,9 +166,131 @@ function MessageContent_({
           },
         }}
       >
-        {content}
+        {cleanContent}
       </AIElementMessageResponse>
     </AIElementMessageContent>
   );
 }
+
+/**
+ * Citations list component that displays all sources at the top
+ */
+function CitationsList({ citations }: { citations: Citation[] }) {
+  if (citations.length === 0) return null;
+
+  return (
+    <div className="mb-4 rounded-lg border bg-muted/30 p-3">
+      <div className="mb-2 flex items-center gap-2 text-sm font-medium text-muted-foreground">
+        <LinkIcon className="size-4" />
+        <span>Sources ({citations.length})</span>
+      </div>
+      <div className="flex flex-wrap gap-2">
+        {citations.map((citation) => (
+          <CitationBadge key={citation.id} citation={citation} />
+        ))}
+      </div>
+    </div>
+  );
+}
+
+/**
+ * Single citation badge in the citations list
+ */
+function CitationBadge({ citation }: { citation: Citation }) {
+  const domain = extractDomainFromUrl(citation.url);
+
+  return (
+    <InlineCitationCard>
+      <HoverCardTrigger asChild>
+        <a
+          href={citation.url}
+          target="_blank"
+          rel="noopener noreferrer"
+          className="inline-flex"
+        >
+          <Badge
+            variant="secondary"
+            className="cursor-pointer gap-1 rounded-full px-2.5 py-1 text-xs font-normal hover:bg-secondary/80"
+          >
+            {domain}
+            <ExternalLinkIcon className="size-3" />
+          </Badge>
+        </a>
+      </HoverCardTrigger>
+      <InlineCitationCardBody>
+        <div className="p-3">
+          <InlineCitationSource
+            title={citation.title}
+            url={citation.url}
+            description={citation.snippet}
+          />
+          <a
+            href={citation.url}
+            target="_blank"
+            rel="noopener noreferrer"
+            className="text-primary mt-2 inline-flex items-center gap-1 text-xs hover:underline"
+          >
+            Visit source
+            <ExternalLinkIcon className="size-3" />
+          </a>
+        </div>
+      </InlineCitationCardBody>
+    </InlineCitationCard>
+  );
+}
+
+/**
+ * Citation link component that renders as a hover card badge
+ */
+function CitationLink({
+  citation,
+  href,
+  children,
+}: {
+  citation: Citation;
+  href: string;
+  children: React.ReactNode;
+}) {
+  const domain = extractDomainFromUrl(href);
+
+  return (
+    <InlineCitationCard>
+      <HoverCardTrigger asChild>
+        <a
+          href={href}
+          target="_blank"
+          rel="noopener noreferrer"
+          className="inline-flex items-center"
+          onClick={(e) => e.stopPropagation()}
+        >
+          <Badge
+            variant="secondary"
+            className="mx-0.5 cursor-pointer gap-1 rounded-full px-2 py-0.5 text-xs font-normal hover:bg-secondary/80"
+          >
+            {children ?? domain}
+            <ExternalLinkIcon className="size-3" />
+          </Badge>
+        </a>
+      </HoverCardTrigger>
+      <InlineCitationCardBody>
+        <div className="p-3">
+          <InlineCitationSource
+            title={citation.title}
+            url={href}
+            description={citation.snippet}
+          />
+          <a
+            href={href}
+            target="_blank"
+            rel="noopener noreferrer"
+            className="text-primary mt-2 inline-flex items-center gap-1 text-xs hover:underline"
+          >
+            Visit source
+            <ExternalLinkIcon className="size-3" />
+          </a>
+        </div>
+      </InlineCitationCardBody>
+    </InlineCitationCard>
+  );
+}
 const MessageContent = memo(MessageContent_);