articles: discussion threads + Related Forum Posts sidebar

ArticleComments component renders under every news + articles detail
page. Anonymous visitors see all existing comments and a Sign-in CTA;
signed-in members get a composer, threaded replies, and up/down votes.
AI personas are tagged with a small AI chip so readers know what
they're interacting with — same persona TZ rules from #63 apply.

Schema extensions on bb.article_comments: parent_comment_id self-FK
for one-level threading, denormalized author fields, vote counters,
is_ai_seeded flag, status enum. user_id relaxed to nullable so AI rows
can exist without a real user_profile; CHECK constraint enforces 'real
user OR is_ai_seeded' so anonymous comments can never sneak through.
forum_votes.target_type check expanded to include 'comment' — same
polymorphic vote table powers thread/reply/comment votes.

New Related Forum Posts sidebar on both /articles/[slug] and
/news/[slug]. getRelatedForumThreads() does title-keyword ILIKE OR
against forum_threads, ranked by reply_count + recency, with recently-
active fallback so the box is never empty. 6 threads per article.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/articles/legacy-source.ts

@@ -408,6 +408,99 @@ export async function searchLegacyArticles(
   return merged.slice(0, limit).map((m) => m.article);
 }
 
+/** Pick keywords from an article title to match against forum threads.
+    Drops short/common words; keeps brand/product nouns. */
+function titleKeywords(s: string): string[] {
+  const STOP = new Set([
+    "the","a","an","and","or","but","of","for","to","in","on","at","with","from",
+    "by","as","is","are","was","were","be","been","being","this","that","these",
+    "those","it","its","new","now","more","most","how","why","when","where","what",
+    "who","which","also","plus","via","over","under","into","than","then","each",
+    "all","any","every","some","just","one","two","three","four","five","six",
+  ]);
+  return Array.from(new Set(
+    s.toLowerCase()
+      .replace(/[^a-z0-9 -]+/g, " ")
+      .split(/\s+/)
+      .filter((w) => w.length >= 4 && !STOP.has(w))
+  )).slice(0, 6);
+}
+
+export interface RelatedForumThread {
+  id: string;
+  title: string;
+  body: string;
+  reply_count: number;
+  view_count: number;
+  vote_score: number;
+  last_reply_at: string | null;
+  category_slug: string | null;
+  category_name: string | null;
+}
+
+/** Find forum threads relevant to an article's title. Strategy: extract
+    longish title tokens, match any against forum_threads.title (ILIKE OR),
+    rank by reply_count + recency, cap at `limit`. Falls back to recently-
+    active threads if no keyword matches. */
+export async function getRelatedForumThreads(
+  articleTitle: string,
+  limit = 6,
+): Promise<RelatedForumThread[]> {
+  const kws = titleKeywords(articleTitle);
+  let rows: any[] = [];
+  if (kws.length > 0) {
+    const filter = kws.map((k) => `title.ilike.%${k.replace(/[%_]/g, "")}%`).join(",");
+    try {
+      const { data } = await client()
+        .from("forum_threads")
+        .select("id, title, body, reply_count, view_count, vote_score, last_reply_at, category_id")
+        .or(filter)
+        .order("reply_count", { ascending: false })
+        .order("last_reply_at", { ascending: false, nullsFirst: false })
+        .limit(limit * 2);
+      rows = data || [];
+    } catch { /* ignore */ }
+  }
+  if (rows.length < limit) {
+    // Top up with recently-active threads so we never render an empty box.
+    try {
+      const { data } = await client()
+        .from("forum_threads")
+        .select("id, title, body, reply_count, view_count, vote_score, last_reply_at, category_id")
+        .order("last_reply_at", { ascending: false, nullsFirst: false })
+        .limit(limit * 2);
+      const seen = new Set(rows.map((r) => r.id));
+      for (const r of data || []) {
+        if (rows.length >= limit * 2) break;
+        if (!seen.has(r.id)) rows.push(r);
+      }
+    } catch { /* ignore */ }
+  }
+  // Resolve category slug/name in one batch
+  const catIds = Array.from(new Set(rows.map((r) => r.category_id).filter(Boolean)));
+  let catById = new Map<string, { slug: string; name: string }>();
+  if (catIds.length) {
+    try {
+      const { data } = await client()
+        .from("forum_categories")
+        .select("id, slug, name")
+        .in("id", catIds);
+      for (const c of data || []) catById.set(c.id, { slug: c.slug, name: c.name });
+    } catch { /* ignore */ }
+  }
+  return rows.slice(0, limit).map((r) => ({
+    id: r.id,
+    title: r.title,
+    body: r.body,
+    reply_count: r.reply_count ?? 0,
+    view_count: r.view_count ?? 0,
+    vote_score: r.vote_score ?? 0,
+    last_reply_at: r.last_reply_at,
+    category_slug: catById.get(r.category_id)?.slug || null,
+    category_name: catById.get(r.category_id)?.name || null,
+  }));
+}
+
 export async function getLegacyRecentSlugs(limit = 200): Promise<string[]> {
   let legacy: string[] = [];
   let rewrites: string[] = [];