Trending: public /api/trending and a list_trending_topics MCP tool

app/(marketing)/trending/page.tsx

@@ -84,7 +84,13 @@ export default async function TrendingPage() {
               ))}
             </tbody>
           </table>
-          {newest && <p className="mt-3 text-xs text-[var(--color-muted)]">Updated {updated(newest)}.</p>}
+          <p className="mt-3 text-xs text-[var(--color-muted)]">
+            {newest && `Updated ${updated(newest)}. `}Also as{" "}
+            <a href="/api/trending" className="underline">
+              JSON
+            </a>{" "}
+            and the <code>list_trending_topics</code> MCP tool.
+          </p>
         </div>
       )}
 

app/api/mcp/route.ts

@@ -17,6 +17,7 @@ import { registerAffiliateTools } from "@/lib/mcp/affiliate";
 import { registerActorTools } from "@/lib/mcp/actors";
 import { registerCreditTools } from "@/lib/mcp/credits";
 import { registerWebhookTools } from "@/lib/mcp/webhooks";
+import { registerTrendTools } from "@/lib/mcp/trends";
 
 export const runtime = "nodejs";
 export const dynamic = "force-dynamic";
@@ -32,6 +33,7 @@ const handler = createMcpHandler(
     registerActorTools(server);
     registerCreditTools(server);
     registerWebhookTools(server);
+    registerTrendTools(server);
   },
   {},
   // The route is mounted at /api/mcp, so mcp-handler must derive its endpoint

app/api/trending/route.ts

@@ -0,0 +1,17 @@
+// GET /api/trending?limit=50 — the list behind /trending, open and with no key.
+// The token-authed /api/ads/v1/trends adds what advertisers need on top.
+
+import { NextResponse, type NextRequest } from "next/server";
+import { serviceClient } from "@/lib/supabase/service";
+import { publicTrendList } from "@/lib/ads/trendList";
+
+export const runtime = "nodejs";
+export const dynamic = "force-dynamic";
+
+export async function GET(req: NextRequest) {
+  const limit = Number(new URL(req.url).searchParams.get("limit")) || 50;
+  const list = await publicTrendList(serviceClient(), { limit });
+  return NextResponse.json(list, {
+    headers: { "cache-control": "public, max-age=3600", "access-control-allow-origin": "*" },
+  });
+}

lib/ads/trendList.ts

@@ -0,0 +1,31 @@
+// The trend list as outsiders see it: the public API and the MCP tool answer with
+// this, so the two cannot drift apart.
+
+import type { SupabaseClient } from "@supabase/supabase-js";
+import { currentTrends } from "./trends";
+import { TREND_MAX_AGE_HOURS, TREND_SOURCE, TREND_WINDOW_DAYS, trendsAreStale } from "./trending";
+
+export async function publicTrendList(sb: SupabaseClient, options: { limit?: number; now?: number } = {}) {
+  const now = options.now ?? Date.now();
+  const limit = Math.min(200, Math.max(1, Math.round(Number(options.limit)) || 50));
+  const signals = await currentTrends(sb, { limit, includeStale: true, now });
+  const newest = signals.reduce<string | null>(
+    (latest, signal) => (!latest || (signal.ingestedAt ?? "") > latest ? (signal.ingestedAt ?? latest) : latest),
+    null,
+  );
+  return {
+    source: TREND_SOURCE,
+    window_days: TREND_WINDOW_DAYS,
+    ingested_at: newest,
+    // Past this the list no longer steers delivery, and an agent should know.
+    stale: signals.length > 0 && trendsAreStale(newest, now),
+    max_age_hours: TREND_MAX_AGE_HOURS,
+    topics: signals.map((signal) => ({
+      topic: signal.label ?? signal.topic,
+      match_key: signal.topic,
+      score: signal.score,
+      feeds: signal.mentions,
+      prior_feeds: signal.priorMentions,
+    })),
+  };
+}

lib/ads/trends.ts

@@ -18,6 +18,9 @@ export type IngestResult =
   | { ok: true; source: string; windowDays: number; stored: number; removed: number; generatedAt: string | null }
   | { ok: false; status: number; error: string };
 
+// Real news, but nothing to publish on a sales page or sell an ad against.
+const UNSAFE_TOPIC = /\b(abuse|assault|rape\w*|sexual\w*|sex|porn\w*|nude\w*|child|children|minor|minors|murder\w*|suicide|massacre|shooting|stabbing|beheaded|terror\w*)\b/i;
+
 const clampNumber = (value: unknown, min: number, max: number, fallback: number): number => {
   const n = Number(value);
   if (!Number.isFinite(n)) return fallback;
@@ -56,7 +59,7 @@ export function parseTrendPayload(
   for (const item of rawTopics) {
     const row = (item ?? {}) as Record<string, unknown>;
     const topic = normalizeTopic(String(row.topic ?? ""));
-    if (!topic || seen.has(topic)) continue;
+    if (!topic || seen.has(topic) || UNSAFE_TOPIC.test(String(row.topic))) continue;
     seen.add(topic);
     signals.push({
       source,

lib/mcp/trends.ts

@@ -0,0 +1,19 @@
+import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { z } from "zod";
+import { serviceClient } from "@/lib/supabase/service";
+import { publicTrendList } from "@/lib/ads/trendList";
+
+export function registerTrendTools(server: McpServer): void {
+  server.registerTool(
+    "list_trending_topics",
+    {
+      description:
+        "Subjects blogs and news sites are writing about more than last week, the list trending ad targeting matches on. Feeds are counted in a sample, so read them as movement. `stale: true` means the list no longer steers delivery.",
+      inputSchema: { limit: z.number().int().min(1).max(200).optional().describe("Default 50.") },
+    },
+    async (args) => {
+      const list = await publicTrendList(serviceClient(), { limit: args.limit });
+      return { content: [{ type: "text" as const, text: JSON.stringify(list, null, 2) }] };
+    },
+  );
+}

tests/ads-trend-list.test.ts

@@ -0,0 +1,46 @@
+import { describe, expect, it } from "vitest";
+import { publicTrendList } from "@/lib/ads/trendList";
+
+const NOW = Date.parse("2026-11-07T12:00:00Z");
+const row = (topic: string, label: string, ingested_at: string) => ({
+  source: "rssamp",
+  topic,
+  label,
+  mentions: 60,
+  prior_mentions: 2,
+  score: 40,
+  window_days: 7,
+  generated_at: null,
+  ingested_at,
+});
+
+function client(rows: unknown[]) {
+  const chain = {
+    select: () => chain,
+    eq: () => chain,
+    order: () => chain,
+    limit: async () => ({ data: rows, error: null }),
+  };
+  return { from: () => chain } as never;
+}
+
+describe("publicTrendList", () => {
+  it("shows the subject as written and keeps the match key beside it", async () => {
+    const list = await publicTrendList(client([row("midterm result", "midterm results", "2026-11-07T11:00:00Z")]), { now: NOW });
+    expect(list.stale).toBe(false);
+    expect(list.topics).toEqual([
+      { topic: "midterm results", match_key: "midterm result", score: 40, feeds: 60, prior_feeds: 2 },
+    ]);
+  });
+
+  it("says when the list has stopped steering delivery", async () => {
+    const list = await publicTrendList(client([row("a", "a", "2026-11-01T11:00:00Z")]), { now: NOW });
+    expect(list.stale).toBe(true);
+    expect(list.topics).toHaveLength(1);
+  });
+
+  it("is not stale when there is simply nothing yet", async () => {
+    const list = await publicTrendList(client([]), { now: NOW });
+    expect(list).toMatchObject({ stale: false, ingested_at: null, topics: [] });
+  });
+});

tests/ads-trending.test.ts

@@ -287,3 +287,10 @@ describe("asking for trending targeting", () => {
     expect(promoLine(null)).toBe("");
   });
 });
+
+describe("unsafe topics", () => {
+  it("are dropped before they can be shown or targeted", () => {
+    const parsed = parseTrendPayload({ topics: [{ topic: "abuse material", score: 9 }, { topic: "midterm results", score: 5 }] });
+    expect(parsed.ok && parsed.signals.map((s) => s.label)).toEqual(["midterm results"]);
+  });
+});