Normalize forum URLs as nostr events and rendered them as titles

src/lib/chat.svelte.ts

@@ -4,6 +4,7 @@ import { RELAY_URL } from "$lib/config";
 import { auth } from "$lib/auth.svelte";
 import { ingestNostrUser } from "$lib/profiles.svelte";
 import { extractMentionPubkeys, buildPTagHints } from "$lib/mentions";
+import { convertForumUrls } from "$lib/linkify";
 
 export type ChatMessageData = {
   id: string;
@@ -131,6 +132,8 @@ export async function sendChatMessage(
   if (!currentGroup) throw new Error("No room selected");
   const ownPubkey = await auth.signer.getPublicKey();
 
+  content = convertForumUrls(content);
+
   const previousRefs = messages
     .filter((m) => m.pubkey !== ownPubkey)
     .slice(-3)

src/lib/components/ChatContent.svelte

@@ -1,6 +1,11 @@
 <script lang="ts">
   import { loadNostrUser, type NostrUser } from "@nostr/gadgets/metadata";
   import { tokenizeChat } from "$lib/linkify";
+  import {
+    resolveThreadRef,
+    threadRefHref,
+    type ThreadRef,
+  } from "$lib/threadRefs";
 
   type Props = {
     content: string;
@@ -12,14 +17,21 @@
   const tokens = $derived(tokenizeChat(content));
 
   let resolvedUsers = $state<Record<string, NostrUser>>({});
+  let resolvedThreads = $state<Record<string, ThreadRef>>({});
 
   $effect(() => {
     for (const t of tokens) {
-      if (t.type !== "mention") continue;
+      if (t.type === "mention") {
         if (resolvedUsers[t.pubkey] || profiles[t.pubkey]) continue;
         loadNostrUser(t.pubkey).then((u) => {
           resolvedUsers = { ...resolvedUsers, [t.pubkey]: u };
         });
+      } else if (t.type === "entity" && t.id && !resolvedThreads[t.id]) {
+        const id = t.id;
+        resolveThreadRef(id).then((ref) => {
+          if (ref) resolvedThreads = { ...resolvedThreads, [id]: ref };
+        });
+      }
     }
   });
 </script>
@@ -31,12 +43,17 @@
         target="_blank"
         rel="noopener noreferrer"
         class="text-brand hover:underline">@{u?.shortName ?? t.fallback}</a
-    >{:else if t.type === "entity"}<a
+      >{:else if t.type === "entity"}{@const ref = t.id
+        ? resolvedThreads[t.id]
+        : undefined}{#if ref}<a
+          href={threadRefHref(ref)}
+          class="text-brand hover:underline">{ref.title}</a
+        >{:else}<a
           href={t.href}
           target="_blank"
           rel="noopener noreferrer"
           class="text-brand hover:underline">{t.label}</a
-    >{:else if t.type === "link"}<a
+        >{/if}{:else if t.type === "link"}<a
         href={t.href}
         title={t.href}
         target="_blank"

src/lib/components/ChatSidebar.svelte

@@ -15,6 +15,9 @@
   import type { NostrUser } from "@nostr/gadgets/metadata";
   import MentionAutocomplete from "$lib/components/MentionAutocomplete.svelte";
   import ChatContent from "$lib/components/ChatContent.svelte";
+  import { shortNostrEntity } from "$lib/linkify";
+  import { resolveThreadRef } from "$lib/threadRefs";
+  import * as nip19 from "@nostr/tools/nip19";
 
   type Props = {
     expanded?: boolean;
@@ -87,9 +90,43 @@
     });
   }
 
+  const ENTITY_PATTERN = "nostr:(note1[a-z0-9]+|nevent1[a-z0-9]+)";
+
+  // Resolved thread titles, keyed by the bech32 entity (note1…/nevent1…).
+  let resolvedTitles = $state<Record<string, string>>({});
+
+  $effect(() => {
+    const re = new RegExp(ENTITY_PATTERN, "gi");
+    const entities = new Set<string>();
+    for (const m of messages)
+      for (const match of m.content.matchAll(re))
+        entities.add(match[1].toLowerCase());
+    for (const entity of entities) {
+      if (resolvedTitles[entity]) continue;
+      let id: string | null = null;
+      try {
+        const d = nip19.decode(entity);
+        if (d.type === "note") id = d.data;
+        else if (d.type === "nevent") id = d.data.id;
+      } catch {
+        // Invalid bech32, skip
+      }
+      if (!id) continue;
+      resolveThreadRef(id).then((ref) => {
+        if (ref) resolvedTitles = { ...resolvedTitles, [entity]: ref.title };
+      });
+    }
+  });
+
   function truncate(s: string, n = 60) {
-    // Collapse mentions to @… so the preview stays readable.
+    // Collapse mentions to @… and show thread refs as their title.
-    const stripped = s.replace(/nostr:(?:npub1|nprofile1)[a-z0-9]+/gi, "@…");
+    const stripped = s
+      .replace(/nostr:(?:npub1|nprofile1)[a-z0-9]+/gi, "@…")
+      .replace(
+        new RegExp(ENTITY_PATTERN, "gi"),
+        (_m, entity) =>
+          resolvedTitles[entity.toLowerCase()] ?? shortNostrEntity(entity),
+      );
     const t = stripped.replace(/\s+/g, " ").trim();
     return t.length > n ? t.slice(0, n) + "…" : t;
   }
@@ -190,7 +227,7 @@
 
 <aside
   bind:this={asideEl}
-  class="flex-1 flex-col bg-white dark:bg-neutral-900 px-4 pt-4 pb-20 min-[1540px]:rounded-tr-xl md:absolute md:top-6 md:right-0 md:z-10 md:h-[calc(100%-1.5rem)] md:flex-none md:rounded-tl-xl md:px-6 md:py-6 md:transition-all md:duration-200
+  class="flex-1 flex-col bg-white px-4 pt-4 pb-20 min-[1540px]:rounded-tr-xl md:absolute md:top-6 md:right-0 md:z-10 md:h-[calc(100%-1.5rem)] md:flex-none md:rounded-tl-xl md:px-6 md:py-6 md:transition-all md:duration-200 dark:bg-neutral-900
 		{mobileActive ? 'flex' : 'hidden'} md:flex
 		{expanded ? 'md:w-150 md:shadow-2xl' : 'md:w-80 md:shadow-lg'}"
 >
@@ -198,7 +235,7 @@
     <span class="text-brand text-[1.5rem] leading-7">Chat</span>
     <button
       onclick={onToggle}
-      class="hidden rounded bg-neutral-100 dark:bg-neutral-800 transition-colors hover:bg-neutral-200 dark:hover:bg-neutral-700 md:block"
+      class="hidden rounded bg-neutral-100 transition-colors hover:bg-neutral-200 md:block dark:bg-neutral-800 dark:hover:bg-neutral-700"
       aria-label={expanded ? "Collapse chat" : "Expand chat"}
     >
       <svg
@@ -228,7 +265,9 @@
     class="no-scrollbar -mr-6 flex flex-1 flex-col overflow-y-auto pr-6"
   >
     {#if messages.length === 0}
-      <div class="m-auto py-8 text-center text-sm text-neutral-400 dark:text-neutral-500">
+      <div
+        class="m-auto py-8 text-center text-sm text-neutral-400 dark:text-neutral-500"
+      >
         No messages yet.
       </div>
     {:else}
@@ -247,17 +286,19 @@
                 />
               {:else}
                 <span
-                  class="flex h-6 w-6 shrink-0 items-center justify-center rounded-full bg-neutral-200 dark:bg-neutral-700 text-xs font-semibold text-neutral-500 dark:text-neutral-400"
+                  class="flex h-6 w-6 shrink-0 items-center justify-center rounded-full bg-neutral-200 text-xs font-semibold text-neutral-500 dark:bg-neutral-700 dark:text-neutral-400"
                 >
                   {author.name[0].toUpperCase()}
                 </span>
               {/if}
-              <span class="font-medium text-neutral-500 dark:text-neutral-400">{author.name}</span>
+              <span class="font-medium text-neutral-500 dark:text-neutral-400"
+                >{author.name}</span
+              >
               <div class="ml-auto flex items-center gap-1">
                 <div class="relative">
                   <button
                     onclick={(e) => toggleMenu(msg.id, e)}
-                    class="flex items-center justify-center rounded p-0.5 text-neutral-300 dark:text-neutral-600 transition-colors hover:bg-neutral-100 dark:hover:bg-neutral-800 hover:text-neutral-500 dark:hover:text-neutral-400"
+                    class="flex items-center justify-center rounded p-0.5 text-neutral-300 transition-colors hover:bg-neutral-100 hover:text-neutral-500 dark:text-neutral-600 dark:hover:bg-neutral-800 dark:hover:text-neutral-400"
                     aria-label="Message actions"
                     aria-haspopup="menu"
                     aria-expanded={openMenuId === msg.id}
@@ -277,7 +318,7 @@
                     <div
                       role="menu"
                       style={`${menuPos.top !== undefined ? `top:${menuPos.top}px` : `bottom:${menuPos.bottom}px`};right:${menuPos.right}px`}
-                      class="fixed z-50 w-36 rounded-lg border border-neutral-100 dark:border-neutral-800 bg-white dark:bg-neutral-900 py-1 text-sm shadow-lg"
+                      class="fixed z-50 w-36 rounded-lg border border-neutral-100 bg-white py-1 text-sm shadow-lg dark:border-neutral-800 dark:bg-neutral-900"
                     >
                       <button
                         role="menuitem"
@@ -310,7 +351,7 @@
             <div class="mt-0.5">
               {#if msg.replyToId}
                 <div
-                  class="mb-1 border-l-2 border-neutral-300 dark:border-neutral-600 pl-2 text-xs text-neutral-500 dark:text-neutral-400"
+                  class="mb-1 border-l-2 border-neutral-300 pl-2 text-xs text-neutral-500 dark:border-neutral-600 dark:text-neutral-400"
                 >
                   {#if parent}
                     <span class="font-medium">{parentAuthor?.name}</span>:
@@ -330,14 +371,16 @@
     {/if}
   </div>
 
-  <div class="border-t border-neutral-200 dark:border-neutral-700 pt-4">
+  <div class="border-t border-neutral-200 pt-4 dark:border-neutral-700">
     {#if replyTarget}
       {@const replyAuthor = resolveAuthor(replyTarget.pubkey)}
       <div
-        class="mb-2 flex items-start gap-2 rounded bg-neutral-50 dark:bg-neutral-800 px-2 py-1.5 text-xs text-neutral-600 dark:text-neutral-400"
+        class="mb-2 flex items-start gap-2 rounded bg-neutral-50 px-2 py-1.5 text-xs text-neutral-600 dark:bg-neutral-800 dark:text-neutral-400"
       >
         <div class="min-w-0 flex-1">
-          <span class="text-neutral-400 dark:text-neutral-500">↳ Reply to </span>
+          <span class="text-neutral-400 dark:text-neutral-500"
+            >↳ Reply to
+          </span>
           <span class="font-medium">{replyAuthor.name}</span>:
           <span class="text-neutral-500 dark:text-neutral-400"
             >{truncate(replyTarget.content, 80)}</span
@@ -345,7 +388,7 @@
         </div>
         <button
           onclick={cancelReply}
-          class="shrink-0 text-neutral-400 dark:text-neutral-500 hover:text-neutral-600 dark:hover:text-neutral-400"
+          class="shrink-0 text-neutral-400 hover:text-neutral-600 dark:text-neutral-500 dark:hover:text-neutral-400"
           aria-label="Cancel reply"
         >
           ✕

src/lib/components/MessageEditor.svelte

@@ -4,6 +4,7 @@
   import { BLOSSOM_URL } from "$lib/config";
   import PostContent from "$lib/components/PostContent.svelte";
   import MentionAutocomplete from "$lib/components/MentionAutocomplete.svelte";
+  import { convertForumUrls } from "$lib/linkify";
 
   type Props = {
     value: string;
@@ -32,6 +33,9 @@
   let uploadError = $state<string | null>(null);
   let previewing = $state(false);
 
+  // Mirror the publish transform so the preview shows resolved thread titles.
+  const previewContent = $derived(convertForumUrls(value));
+
   export function focus(opts: { caretAtEnd?: boolean } = {}) {
     editorEl?.focus(opts);
   }
@@ -80,13 +84,15 @@
 <div class="flex flex-col {previewing ? 'min-h-0 flex-1' : ''}">
   {#if previewing}
     <div
-      class="max-h-[70vh] min-h-0 w-full flex-1 overflow-auto rounded-t border border-neutral-200 dark:border-neutral-700 px-3 py-2 {minHeightClass}"
+      class="max-h-[70vh] min-h-0 w-full flex-1 overflow-auto rounded-t border border-neutral-200 px-3 py-2 dark:border-neutral-700 {minHeightClass}"
       aria-label="Preview"
     >
       {#if value.trim()}
-        <PostContent content={value} {threadEventAuthors} />
+        <PostContent content={previewContent} {threadEventAuthors} />
       {:else}
-        <p class="text-neutral-400 dark:text-neutral-500 italic">Nothing to preview</p>
+        <p class="text-neutral-400 italic dark:text-neutral-500">
+          Nothing to preview
+        </p>
       {/if}
     </div>
   {:else}
@@ -101,14 +107,14 @@
     />
   {/if}
   <div
-    class="flex flex-shrink-0 items-center gap-4 rounded-b border border-t-0 border-neutral-200 dark:border-neutral-700 bg-neutral-50 dark:bg-neutral-800 px-3 py-2 text-sm"
+    class="flex flex-shrink-0 items-center gap-4 rounded-b border border-t-0 border-neutral-200 bg-neutral-50 px-3 py-2 text-sm dark:border-neutral-700 dark:bg-neutral-800"
   >
     <button
       type="button"
       onclick={onUploadClick}
       disabled={uploading || disabled || previewing || !BLOSSOM_URL}
       title={!BLOSSOM_URL ? "Blossom server not configured" : ""}
-      class="inline-flex items-center gap-1.5 text-neutral-600 dark:text-neutral-400 hover:text-neutral-900 dark:hover:text-neutral-100 disabled:cursor-not-allowed disabled:opacity-50"
+      class="inline-flex items-center gap-1.5 text-neutral-600 hover:text-neutral-900 disabled:cursor-not-allowed disabled:opacity-50 dark:text-neutral-400 dark:hover:text-neutral-100"
     >
       <svg
         width="16"
@@ -135,7 +141,7 @@
       onclick={togglePreview}
       disabled={disabled || uploading}
       aria-pressed={previewing}
-      class="ml-auto inline-flex items-center gap-1.5 text-neutral-600 dark:text-neutral-400 hover:text-neutral-900 dark:hover:text-neutral-100 disabled:cursor-not-allowed disabled:opacity-50"
+      class="ml-auto inline-flex items-center gap-1.5 text-neutral-600 hover:text-neutral-900 disabled:cursor-not-allowed disabled:opacity-50 dark:text-neutral-400 dark:hover:text-neutral-100"
     >
       <svg
         width="16"

src/lib/components/PostContent.svelte

@@ -1,6 +1,11 @@
 <script lang="ts">
   import { loadNostrUser, type NostrUser } from "@nostr/gadgets/metadata";
   import * as nip19 from "@nostr/tools/nip19";
+  import {
+    resolveThreadRef,
+    threadRefHref,
+    type ThreadRef,
+  } from "$lib/threadRefs";
   import { parse } from "@djot/djot";
   import type {
     Block as DjBlock,
@@ -147,7 +152,7 @@
     | { type: "text"; value: string }
     | { type: "link"; href: string; label: string }
     | { type: "mention"; pubkey: string; entity: string; fallback: string }
-    | { type: "entity"; entity: string; label: string }
+    | { type: "entity"; entity: string; label: string; id?: string }
     | { type: "thread-quote"; pubkey: string; eventId: string }
     | { type: "strong"; children: Inline[] }
     | { type: "em"; children: Inline[] }
@@ -201,14 +206,14 @@
         const author = threadEventAuthors[id];
         if (author)
           return { type: "thread-quote", pubkey: author, eventId: id };
-        return { type: "entity", entity, label: shortEntity(entity) };
+        return { type: "entity", entity, label: shortEntity(entity), id };
       }
       if (decoded.type === "nevent") {
         const id = decoded.data.id;
         const author = threadEventAuthors[id];
         if (author)
           return { type: "thread-quote", pubkey: author, eventId: id };
-        return { type: "entity", entity, label: shortEntity(entity) };
+        return { type: "entity", entity, label: shortEntity(entity), id };
       }
       if (decoded.type === "naddr") {
         return { type: "entity", entity, label: shortEntity(entity) };
@@ -548,13 +553,16 @@
   });
 
   let resolvedUsers = $state<Record<string, NostrUser>>({});
+  let resolvedThreads = $state<Record<string, ThreadRef>>({});
 
   $effect(() => {
     const seen = new Set<string>();
+    const seenRefs = new Set<string>();
     const collect = (inlines: Inline[]) => {
       for (const inline of inlines) {
         if (inline.type === "mention" || inline.type === "thread-quote")
           seen.add(inline.pubkey);
+        else if (inline.type === "entity" && inline.id) seenRefs.add(inline.id);
         else if (
           inline.type === "strong" ||
           inline.type === "em" ||
@@ -582,6 +590,12 @@
         resolvedUsers = { ...resolvedUsers, [pubkey]: u };
       });
     }
+    for (const id of seenRefs) {
+      if (resolvedThreads[id]) continue;
+      resolveThreadRef(id).then((ref) => {
+        if (ref) resolvedThreads = { ...resolvedThreads, [id]: ref };
+      });
+    }
   });
 </script>
 
@@ -607,7 +621,7 @@
       {@const u = profiles[inline.pubkey] ?? resolvedUsers[inline.pubkey]}
       <a
         href="#post-{inline.eventId}"
-        class="-ml-3 block bg-neutral-100 dark:bg-neutral-800 py-1 pl-3 leading-4 font-normal text-neutral-700 dark:text-neutral-300 no-underline hover:bg-neutral-200 dark:hover:bg-neutral-700"
+        class="-ml-3 block bg-neutral-100 py-1 pl-3 leading-4 font-normal text-neutral-700 no-underline hover:bg-neutral-200 dark:bg-neutral-800 dark:text-neutral-300 dark:hover:bg-neutral-700"
         >{u?.shortName ?? inline.pubkey.slice(0, 8)} said
         <svg
           class="mb-0.5 inline w-3"
@@ -624,12 +638,19 @@
         >
       </a>
     {:else if inline.type === "entity"}
+      {@const ref = inline.id ? resolvedThreads[inline.id] : undefined}
+      {#if ref}
+        <a href={threadRefHref(ref)} class="text-brand hover:underline"
+          >{ref.title}</a
+        >
+      {:else}
         <a
           href="https://njump.me/{inline.entity}"
           target="_blank"
           rel="noopener noreferrer"
           class="text-brand break-all hover:underline">{inline.label}</a
         >
+      {/if}
     {:else if inline.type === "strong"}
       <strong>{@render renderInlines(inline.children)}</strong>
     {:else if inline.type === "em"}
@@ -683,7 +704,7 @@
       />
     {:else if block.type === "blockquote"}
       <blockquote
-        class="my-3 mb-3 border-l-3 border-neutral-200 dark:border-neutral-700 pb-1 pl-3 text-neutral-500 dark:text-neutral-400"
+        class="my-3 mb-3 border-l-3 border-neutral-200 pb-1 pl-3 text-neutral-500 dark:border-neutral-700 dark:text-neutral-400"
       >
         {@render renderBlocks(block.blocks)}
       </blockquote>

src/lib/draft.svelte.ts

@@ -4,6 +4,7 @@ import { withJoin } from "$lib/join.svelte";
 import { activeGroup } from "$lib/active.svelte";
 import { RELAY_URL } from "$lib/config";
 import { extractMentionPubkeys, buildPTagHints } from "$lib/mentions";
+import { convertForumUrls } from "$lib/linkify";
 
 let modalOpen = $state(false);
 let iconized = $state(false);
@@ -98,11 +99,11 @@ export async function publishDraft(): Promise<{
     return { ok: false };
   }
   const t = title.trim();
-  const c = content.trim();
+  if (!t || !content.trim()) {
-  if (!t || !c) {
     publishError = "Title and content are required";
     return { ok: false };
   }
+  const c = convertForumUrls(content.trim());
   const groupId = activeGroup.id;
   if (!groupId) {
     publishError = "No room selected";

src/lib/linkify.ts

@@ -1,4 +1,5 @@
 import * as nip19 from "@nostr/tools/nip19";
+import { RELAY_URL } from "./config";
 
 // Curated TLD list: gTLDs, popular new gTLDs, common ccTLDs
 const TLDS = [
@@ -107,7 +108,14 @@ export type ChatToken =
   | { type: "text"; value: string }
   | { type: "link"; href: string; label: string }
   | { type: "mention"; pubkey: string; entity: string; fallback: string }
-  | { type: "entity"; entity: string; href: string; label: string };
+  | {
+      type: "entity";
+      entity: string;
+      href: string;
+      label: string;
+      // Underlying event id for note/nevent — used to resolve a forum thread.
+      id?: string;
+    };
 
 // Shorten a nostr entity to xxxxxxxx...xxxx
 export function shortNostrEntity(entity: string): string {
@@ -145,7 +153,15 @@ function decodeEntity(entity: string): ChatToken | null {
         entity,
         fallback: shortNostrEntity(entity),
       };
-    if (decoded.type === "note" || decoded.type === "nevent" || decoded.type === "naddr")
+    if (decoded.type === "note" || decoded.type === "nevent")
+      return {
+        type: "entity",
+        entity,
+        href: `https://njump.me/${entity}`,
+        label: shortNostrEntity(entity),
+        id: decoded.type === "note" ? decoded.data : decoded.data.id,
+      };
+    if (decoded.type === "naddr")
       return {
         type: "entity",
         entity,
@@ -193,3 +209,29 @@ export function tokenizeChat(content: string): ChatToken[] {
     out.push({ type: "text", value: content.slice(last) });
   return out;
 }
+
+function escapeRegExp(s: string): string {
+  return s.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+}
+
+// Rewrite same-origin forum thread URLs into nostr entities before publishing,
+// so the reference is portable to other Nostr clients. A `#post-<id>` fragment
+// targets the reply (kind 1111); otherwise the thread itself (kind 11). The
+// author is omitted; the parent is recovered from the reply's own tags on read.
+export function convertForumUrls(content: string): string {
+  if (typeof window === "undefined") return content;
+  const re = new RegExp(
+    `${escapeRegExp(window.location.origin)}/thread/([0-9a-f]{64})\\/?(?:#post-([0-9a-f]{64}))?`,
+    "g",
+  );
+  return content.replace(re, (whole, threadId, replyId) => {
+    try {
+      const nevent = replyId
+        ? nip19.neventEncode({ id: replyId, kind: 1111, relays: [RELAY_URL] })
+        : nip19.neventEncode({ id: threadId, kind: 11, relays: [RELAY_URL] });
+      return `nostr:${nevent}`;
+    } catch {
+      return whole;
+    }
+  });
+}

src/lib/thread.svelte.ts

@@ -9,6 +9,7 @@ import {
   extractQuotedEvents,
   buildPTagHints,
 } from "$lib/mentions";
+import { convertForumUrls } from "$lib/linkify";
 
 const isNostrId = (id: string) => /^[0-9a-f]{64}$/.test(id);
 
@@ -141,6 +142,8 @@ export async function sendReply(content: string, ownPubkey: string) {
   if (!detail) throw new Error("No thread loaded");
   if (!auth.signer) throw new Error("Not logged in");
 
+  content = convertForumUrls(content);
+
   // Use last 3 events not authored by us as previous refs (NIP-29)
   const previousRefs = [...detail.replies, detail.op]
     .filter((p) => p.pubkey !== ownPubkey)

src/lib/threadRefs.ts

@@ -0,0 +1,69 @@
+import { SimplePool } from "@nostr/tools";
+import { RELAY_URL } from "./config";
+
+// A note/nevent that resolves to a forum thread (kind 11) or reply (kind 1111).
+export type ThreadRef = {
+  threadId: string;
+  replyId?: string;
+  title: string;
+  pubkey: string;
+};
+
+const cache = new Map<string, Promise<ThreadRef | null>>();
+
+function titleOf(tags: string[][]): string {
+  return tags.find((t) => t[0] === "title")?.[1] ?? "(untitled)";
+}
+
+async function doResolve(id: string): Promise<ThreadRef | null> {
+  const pool = new SimplePool();
+  try {
+    const events = await pool.querySync([RELAY_URL], {
+      ids: [id],
+      kinds: [11, 1111],
+    });
+    const ev = events[0];
+    if (!ev) return null;
+
+    if (ev.kind === 11)
+      return { threadId: ev.id, title: titleOf(ev.tags), pubkey: ev.pubkey };
+
+    // Reply: recover the root thread from its uppercase root tag.
+    const root = ev.tags.find((t) => t[0] === "E");
+    const rootId = root?.[1];
+    if (!rootId) return null;
+    const threads = await pool.querySync([RELAY_URL], {
+      ids: [rootId],
+      kinds: [11],
+    });
+    const thread = threads[0];
+    return {
+      threadId: rootId,
+      replyId: ev.id,
+      title: thread ? titleOf(thread.tags) : "(untitled)",
+      pubkey: thread?.pubkey ?? root?.[3] ?? ev.pubkey,
+    };
+  } catch {
+    return null;
+  } finally {
+    pool.destroy();
+  }
+}
+
+// Resolve (and cache) a note/nevent id to a forum thread reference, or null if
+// it is not a thread/reply reachable on our relay.
+export function resolveThreadRef(id: string): Promise<ThreadRef | null> {
+  let p = cache.get(id);
+  if (!p) {
+    p = doResolve(id);
+    cache.set(id, p);
+  }
+  return p;
+}
+
+// In-app URL for a resolved reference.
+export function threadRefHref(ref: ThreadRef): string {
+  return ref.replyId
+    ? `/thread/${ref.threadId}#post-${ref.replyId}`
+    : `/thread/${ref.threadId}`;
+}