Add Quote / Repost (NIP-18, roadmap #6)

- publishRepost: kind 6 event with stringified original event as content
  and ["e", id, "", "mention"] + ["p", pubkey] tags
- publishQuote: kind 1 note with user's text + appended nostr:nevent1...
  reference and ["q", id] + ["p", pubkey] tags
- QuoteModal: compose modal with live quoted-note preview (avatar, name,
  truncated content); Ctrl+Enter to post, Escape to close
- NoteCard: "repost" (one-click, shows "reposted ✓") and "quote" (opens
  QuoteModal) added to the actions row alongside reply/like/zap

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/feed/NoteCard.tsx

@@ -6,9 +6,10 @@ import { useUserStore } from "../../stores/user";
 import { useMuteStore } from "../../stores/mute";
 import { useUIStore } from "../../stores/ui";
 import { timeAgo, shortenPubkey } from "../../lib/utils";
-import { publishReaction, publishReply, getNDK } from "../../lib/nostr";
+import { publishReaction, publishReply, publishRepost, getNDK } from "../../lib/nostr";
 import { NoteContent } from "./NoteContent";
 import { ZapModal } from "../zap/ZapModal";
+import { QuoteModal } from "./QuoteModal";
 
 interface NoteCardProps {
   event: NDKEvent;
@@ -40,6 +41,9 @@ export function NoteCard({ event }: NoteCardProps) {
   const [replySent, setReplySent] = useState(false);
   const replyRef = useRef<HTMLTextAreaElement>(null);
   const [showZap, setShowZap] = useState(false);
+  const [showQuote, setShowQuote] = useState(false);
+  const [reposting, setReposting] = useState(false);
+  const [reposted, setReposted] = useState(false);
   const [menuOpen, setMenuOpen] = useState(false);
 
   const handleLike = async () => {
@@ -83,6 +87,17 @@ export function NoteCard({ event }: NoteCardProps) {
     if (e.key === "Escape") setShowReply(false);
   };
 
+  const handleRepost = async () => {
+    if (reposting || reposted) return;
+    setReposting(true);
+    try {
+      await publishRepost(event);
+      setReposted(true);
+    } finally {
+      setReposting(false);
+    }
+  };
+
   return (
     <article className="border-b border-border px-4 py-3 hover:bg-bg-hover transition-colors duration-100 group/card">
       <div className="flex gap-3">
@@ -169,6 +184,21 @@ export function NoteCard({ event }: NoteCardProps) {
               >
                 {liked ? "♥" : "♡"}{reactionCount !== null && reactionCount > 0 ? ` ${reactionCount}` : liked ? " liked" : " like"}
               </button>
+              <button
+                onClick={handleRepost}
+                disabled={reposting || reposted}
+                className={`text-[11px] transition-colors disabled:cursor-default ${
+                  reposted ? "text-accent" : "text-text-dim hover:text-accent"
+                }`}
+              >
+                {reposted ? "reposted ✓" : reposting ? "…" : "repost"}
+              </button>
+              <button
+                onClick={() => setShowQuote(true)}
+                className="text-[11px] text-text-dim hover:text-text transition-colors"
+              >
+                quote
+              </button>
               <button
                 onClick={() => setShowZap(true)}
                 className="text-[11px] text-text-dim hover:text-zap transition-colors"
@@ -186,6 +216,15 @@ export function NoteCard({ event }: NoteCardProps) {
             />
           )}
 
+          {showQuote && (
+            <QuoteModal
+              event={event}
+              authorName={name}
+              authorAvatar={avatar}
+              onClose={() => setShowQuote(false)}
+            />
+          )}
+
           {/* Inline reply box */}
           {showReply && (
             <div className="mt-2 border-l-2 border-border pl-3">

src/components/feed/QuoteModal.tsx

@@ -0,0 +1,102 @@
+import { useState, useRef, useEffect } from "react";
+import { NDKEvent } from "@nostr-dev-kit/ndk";
+import { publishQuote } from "../../lib/nostr";
+
+interface QuoteModalProps {
+  event: NDKEvent;
+  authorName: string;
+  authorAvatar?: string;
+  onClose: () => void;
+  onPublished?: () => void;
+}
+
+export function QuoteModal({ event, authorName, authorAvatar, onClose, onPublished }: QuoteModalProps) {
+  const [text, setText] = useState("");
+  const [publishing, setPublishing] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  const textareaRef = useRef<HTMLTextAreaElement>(null);
+
+  useEffect(() => {
+    textareaRef.current?.focus();
+  }, []);
+
+  const canPublish = text.trim().length > 0 && !publishing;
+
+  const handlePublish = async () => {
+    if (!canPublish) return;
+    setPublishing(true);
+    setError(null);
+    try {
+      await publishQuote(text.trim(), event);
+      onPublished?.();
+      onClose();
+    } catch (err) {
+      setError(`Failed to publish: ${err}`);
+      setPublishing(false);
+    }
+  };
+
+  const handleKeyDown = (e: React.KeyboardEvent) => {
+    if (e.key === "Enter" && (e.ctrlKey || e.metaKey)) handlePublish();
+    if (e.key === "Escape") onClose();
+  };
+
+  const preview = event.content.slice(0, 140) + (event.content.length > 140 ? "…" : "");
+
+  return (
+    <div
+      className="fixed inset-0 bg-black/60 flex items-center justify-center z-50"
+      onClick={(e) => { if (e.target === e.currentTarget) onClose(); }}
+    >
+      <div className="bg-bg border border-border w-full max-w-md mx-4 shadow-2xl">
+        {/* Header */}
+        <div className="flex items-center justify-between px-4 py-3 border-b border-border">
+          <h2 className="text-text text-sm font-medium">Quote note</h2>
+          <button onClick={onClose} className="text-text-dim hover:text-text text-lg leading-none">×</button>
+        </div>
+
+        {/* Compose */}
+        <div className="p-4">
+          <textarea
+            ref={textareaRef}
+            value={text}
+            onChange={(e) => setText(e.target.value)}
+            onKeyDown={handleKeyDown}
+            placeholder="Add your comment…"
+            rows={3}
+            className="w-full bg-transparent text-text text-[13px] placeholder:text-text-dim resize-none focus:outline-none mb-3"
+            style={{ WebkitUserSelect: "text", userSelect: "text" } as React.CSSProperties}
+          />
+
+          {/* Quoted note preview */}
+          <div className="border border-border px-3 py-2.5 bg-bg-raised rounded-sm">
+            <div className="flex items-center gap-2 mb-1.5">
+              {authorAvatar ? (
+                <img src={authorAvatar} alt="" className="w-4 h-4 rounded-sm object-cover" />
+              ) : (
+                <div className="w-4 h-4 rounded-sm bg-accent/20 flex items-center justify-center text-accent text-[8px]">
+                  {authorName.charAt(0).toUpperCase()}
+                </div>
+              )}
+              <span className="text-text-muted text-[11px] font-medium">{authorName}</span>
+            </div>
+            <p className="text-text-dim text-[12px] leading-relaxed whitespace-pre-wrap break-words">{preview}</p>
+          </div>
+
+          {error && <p className="text-danger text-[11px] mt-2">{error}</p>}
+
+          <div className="flex items-center justify-between mt-3">
+            <span className="text-text-dim text-[10px]">Ctrl+Enter to post</span>
+            <button
+              onClick={handlePublish}
+              disabled={!canPublish}
+              className="px-4 py-1.5 text-[11px] bg-accent hover:bg-accent-hover text-white transition-colors disabled:opacity-30 disabled:cursor-not-allowed"
+            >
+              {publishing ? "posting…" : "quote & post"}
+            </button>
+          </div>
+        </div>
+      </div>
+    </div>
+  );
+}