feat: nip-13

src/components/nostr/kinds/BaseEventRenderer.tsx

@@ -52,6 +52,8 @@ import {
   getFavoriteConfig,
   FALLBACK_FAVORITE_CONFIG,
 } from "@/config/favorite-lists";
+import { getPowDifficulty } from "@/lib/nip13-helpers";
+import { Label } from "@/components/ui/label";
 
 /**
  * Universal event properties and utilities shared across all kind renderers
@@ -489,6 +491,7 @@ export function BaseEventContainer({
   };
 }) {
   const { locale } = useGrimoire();
+  const addWindow = useAddWindow();
   const { canSign, signer, pubkey } = useAccount();
   const { settings } = useSettings();
   const [emojiPickerOpen, setEmojiPickerOpen] = useState(false);
@@ -527,6 +530,8 @@ export function BaseEventContainer({
     [signer, pubkey, event],
   );
 
+  const powDifficulty = getPowDifficulty(event);
+
   const relativeTime = formatTimestamp(
     event.created_at,
     "relative",
@@ -568,6 +573,14 @@ export function BaseEventContainer({
               >
                 {relativeTime}
               </span>
+              {powDifficulty !== undefined && (
+                <Label
+                  className="text-[10px] tabular-nums cursor-crosshair hover:text-foreground"
+                  onClick={() => addWindow("nip", { number: 13 }, "NIP 13")}
+                >
+                  PoW {powDifficulty}
+                </Label>
+              )}
             </div>
             <EventMenu
               event={event}

src/components/ui/label.tsx

@@ -9,15 +9,22 @@ interface LabelProps {
    * - md: px-3 py-1
    */
   size?: "sm" | "md";
+  onClick?: (e: React.MouseEvent) => void;
 }
 
 /**
  * Label/Badge component with dotted border styling
  * Used for tags, language indicators, and metadata labels
  */
-export function Label({ children, className, size = "sm" }: LabelProps) {
+export function Label({
+  children,
+  className,
+  size = "sm",
+  onClick,
+}: LabelProps) {
   return (
     <span
+      onClick={onClick}
       className={cn(
         "truncate line-clamp-1 border border-muted border-dotted text-muted-foreground text-xs",
         size === "sm" && "px-2 py-0.5",

src/lib/nip13-helpers.ts

@@ -0,0 +1,33 @@
+import type { NostrEvent } from "@/types/nostr";
+import { getOrComputeCachedValue } from "applesauce-core/helpers";
+
+const PowDifficultySymbol = Symbol("powDifficulty");
+
+/**
+ * Count leading zero bits in a hex string (NIP-13 difficulty).
+ */
+function countLeadingZeroBits(hex: string): number {
+  let count = 0;
+  for (let i = 0; i < hex.length; i++) {
+    const nibble = parseInt(hex[i], 16);
+    if (nibble === 0) {
+      count += 4;
+    } else {
+      count += Math.clz32(nibble) - 28;
+      break;
+    }
+  }
+  return count;
+}
+
+/**
+ * Get the PoW difficulty of an event, or undefined if it has no nonce tag.
+ * Cached on the event object via applesauce helpers.
+ */
+export function getPowDifficulty(event: NostrEvent): number | undefined {
+  return getOrComputeCachedValue(event, PowDifficultySymbol, () => {
+    const nonceTag = event.tags.find((t) => t[0] === "nonce");
+    if (!nonceTag) return undefined;
+    return countLeadingZeroBits(event.id);
+  });
+}