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/app/api/comments/[id]/vote/route.ts

@@ -0,0 +1,72 @@
+/**
+ * POST /api/comments/[id]/vote   { vote: 1 | -1 | 0 }
+ *
+ * Up/down/clear vote on an article comment. Uses the existing
+ * polymorphic forum_votes table (target_type='comment').
+ *
+ * 0 → remove your existing vote (toggle).
+ */
+import { NextRequest, NextResponse } from "next/server";
+import { createClient } from "@/lib/supabase/server";
+
+export async function POST(req: NextRequest, ctx: { params: Promise<{ id: string }> }) {
+  const { id } = await ctx.params;
+  const sb = await createClient();
+  const { data: { user } } = await sb.auth.getUser();
+  if (!user) return NextResponse.json({ error: "Sign in to vote" }, { status: 401 });
+
+  let body: { vote?: number };
+  try { body = await req.json(); }
+  catch { return NextResponse.json({ error: "Invalid JSON" }, { status: 400 }); }
+
+  const v = body.vote === 1 ? 1 : body.vote === -1 ? -1 : 0;
+
+  // Always look up the current vote first so we can compute the diff
+  // and apply it atomically to the comment's denormalized counters.
+  const { data: existing } = await sb
+    .from("forum_votes")
+    .select("id, vote_value")
+    .eq("user_id", user.id)
+    .eq("target_type", "comment")
+    .eq("target_id", id)
+    .maybeSingle();
+
+  let upDelta = 0, downDelta = 0;
+  if (existing) {
+    // Reverse the existing vote's counter contribution first
+    if (existing.vote_value === 1) upDelta -= 1;
+    else if (existing.vote_value === -1) downDelta -= 1;
+
+    if (v === 0) {
+      await sb.from("forum_votes").delete().eq("id", existing.id);
+    } else {
+      await sb.from("forum_votes")
+        .update({ vote_value: v, updated_at: new Date().toISOString() })
+        .eq("id", existing.id);
+      if (v === 1) upDelta += 1; else downDelta += 1;
+    }
+  } else if (v !== 0) {
+    await sb.from("forum_votes").insert({
+      user_id: user.id, target_type: "comment", target_id: id, vote_value: v,
+    });
+    if (v === 1) upDelta += 1; else downDelta += 1;
+  }
+
+  // Apply counter delta to the comment row. Use rpc/raw fragment to add
+  // integers atomically (supabase-js doesn't expose increment; we read &
+  // write — racy under heavy concurrency but acceptable for forum scale).
+  const { data: cur } = await sb
+    .from("article_comments")
+    .select("upvotes, downvotes")
+    .eq("id", id)
+    .maybeSingle();
+  if (cur) {
+    const upvotes = Math.max(0, (cur.upvotes || 0) + upDelta);
+    const downvotes = Math.max(0, (cur.downvotes || 0) + downDelta);
+    await sb.from("article_comments").update({
+      upvotes, downvotes, vote_score: upvotes - downvotes,
+    }).eq("id", id);
+  }
+
+  return NextResponse.json({ ok: true, vote: v });
+}