feat: resolve live Nostr references in blog posts and add embeds

Support naddr/nevent/note slugs for unindexed posts, cache naddr lookups,
render Nostr embeds in markdown, and add a consistency check for events mirrors.

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

frontend/app/blog/[slug]/NostrEmbeds.tsx

@@ -0,0 +1,185 @@
+"use client";
+
+import { useEffect, useMemo, useState } from "react";
+import { nip19 } from "nostr-tools";
+import {
+  loadNostrProfile,
+  resolveEventFromRelays,
+  shortenPubkey,
+  type NostrProfile,
+} from "@/lib/nostr";
+
+function njump(bech32: string): string {
+  return `https://njump.me/${bech32}`;
+}
+
+// Inline @mention chip: avatar + display name, resolved live from the author's
+// kind:0 profile. Falls back to a shortened pubkey until (or unless) it loads.
+export function NostrMention({ bech32 }: { bech32: string }) {
+  const pubkey = useMemo(() => {
+    try {
+      const d = nip19.decode(bech32);
+      if (d.type === "npub") return d.data as string;
+      if (d.type === "nprofile") return (d.data as { pubkey: string }).pubkey;
+    } catch {}
+    return null;
+  }, [bech32]);
+
+  const [profile, setProfile] = useState<NostrProfile | null>(null);
+
+  useEffect(() => {
+    if (!pubkey) return;
+    let cancelled = false;
+    loadNostrProfile(pubkey)
+      .then((p) => !cancelled && setProfile(p))
+      .catch(() => {});
+    return () => {
+      cancelled = true;
+    };
+  }, [pubkey]);
+
+  // Show the username; fall back to a shortened npub only when no profile.
+  const npub = useMemo(() => {
+    if (bech32.startsWith("npub")) return bech32;
+    return pubkey ? nip19.npubEncode(pubkey) : bech32;
+  }, [bech32, pubkey]);
+  const name = profile?.name || profile?.displayName || shortenPubkey(npub);
+
+  return (
+    <a
+      href={njump(bech32)}
+      target="_blank"
+      rel="noopener noreferrer"
+      className="inline-flex items-center gap-1 align-middle text-primary hover:underline font-medium no-underline"
+    >
+      {profile?.picture && (
+        <img
+          src={profile.picture}
+          alt=""
+          className="w-5 h-5 rounded-full object-cover bg-surface-container-high inline-block"
+          onError={(e) => {
+            (e.target as HTMLImageElement).style.display = "none";
+          }}
+        />
+      )}
+      <span>@{name}</span>
+    </a>
+  );
+}
+
+// Compact author line used inside an embedded note.
+function NoteAuthor({ pubkey }: { pubkey: string }) {
+  const [profile, setProfile] = useState<NostrProfile | null>(null);
+  useEffect(() => {
+    let cancelled = false;
+    loadNostrProfile(pubkey)
+      .then((p) => !cancelled && setProfile(p))
+      .catch(() => {});
+    return () => {
+      cancelled = true;
+    };
+  }, [pubkey]);
+  const fallback = useMemo(() => {
+    try {
+      return shortenPubkey(nip19.npubEncode(pubkey));
+    } catch {
+      return shortenPubkey(pubkey);
+    }
+  }, [pubkey]);
+  const name = profile?.name || profile?.displayName || fallback;
+  return (
+    <span className="flex items-center gap-2">
+      {profile?.picture && (
+        <img
+          src={profile.picture}
+          alt=""
+          className="w-6 h-6 rounded-full object-cover bg-surface-container-high"
+          onError={(e) => {
+            (e.target as HTMLImageElement).style.display = "none";
+          }}
+        />
+      )}
+      <span className="font-semibold text-on-surface text-sm">{name}</span>
+    </span>
+  );
+}
+
+// Embedded referenced note (note/nevent/naddr). Renders as a bordered card.
+// Uses span/block elements (not <div>) so it stays valid when the reference
+// sits inside a markdown paragraph.
+export function NostrNote({ bech32 }: { bech32: string }) {
+  const [event, setEvent] = useState<any>(null);
+  const [state, setState] = useState<"loading" | "done" | "error">("loading");
+
+  useEffect(() => {
+    let cancelled = false;
+    setState("loading");
+    resolveEventFromRelays(bech32)
+      .then((ev) => {
+        if (cancelled) return;
+        if (ev) {
+          setEvent(ev);
+          setState("done");
+        } else {
+          setState("error");
+        }
+      })
+      .catch(() => !cancelled && setState("error"));
+    return () => {
+      cancelled = true;
+    };
+  }, [bech32]);
+
+  return (
+    <span className="block my-4 rounded-xl border border-surface-container-high bg-surface-container-low p-4">
+      {state === "loading" && (
+        <span className="flex items-center gap-2 text-on-surface-variant text-sm">
+          <span className="inline-block w-4 h-4 rounded-full border-2 border-primary/30 border-t-primary animate-spin" />
+          Loading note…
+        </span>
+      )}
+      {state === "error" && (
+        <a
+          href={njump(bech32)}
+          target="_blank"
+          rel="noopener noreferrer"
+          className="text-primary hover:underline text-sm break-all"
+        >
+          View referenced note on njump.me
+        </a>
+      )}
+      {state === "done" && event && (
+        <span className="block">
+          <span className="flex items-center justify-between mb-3">
+            <NoteAuthor pubkey={event.pubkey} />
+            <a
+              href={njump(bech32)}
+              target="_blank"
+              rel="noopener noreferrer"
+              className="text-xs text-on-surface-variant/60 hover:text-primary"
+            >
+              View note
+            </a>
+          </span>
+          <span className="block whitespace-pre-wrap break-words text-on-surface-variant text-sm leading-relaxed">
+            {(event.content || "").slice(0, 1000)}
+            {(event.content || "").length > 1000 ? "…" : ""}
+          </span>
+        </span>
+      )}
+    </span>
+  );
+}
+
+// Dispatches a `nostr:<bech32>` reference to the right embed by entity type.
+export function NostrEntity({ bech32 }: { bech32: string }) {
+  let type: string;
+  try {
+    type = nip19.decode(bech32).type;
+  } catch {
+    return <>nostr:{bech32}</>;
+  }
+  if (type === "npub" || type === "nprofile") return <NostrMention bech32={bech32} />;
+  if (type === "note" || type === "nevent" || type === "naddr") return <NostrNote bech32={bech32} />;
+  return <>nostr:{bech32}</>;
+}