fix(pagination): reject out-of-range feed pages

apps/web/components/FeedSection.tsx

@@ -6,6 +6,8 @@ import { listMedia, type ListSort } from "@/lib/queries";
 import { toClientCard } from "@/lib/serialize";
 import { getCurrentUser, canParticipate } from "@/lib/session";
 import { PAGE_SIZE } from "@/lib/queries";
+import { pageCount } from "@/lib/pagination";
+import { notFound } from "next/navigation";
 
 const TABS: { label: string; href: string; sort?: ListSort }[] = [
   { label: "Newest", href: "/" },
@@ -21,6 +23,8 @@ export async function FeedSection({ page }: { page: number }) {
     page,
     userId: user?.id ?? null,
   });
+  const totalPages = pageCount(total, PAGE_SIZE);
+  if (page > totalPages) notFound();
 
   return (
     <>

apps/web/components/Pagination.tsx

@@ -1,4 +1,5 @@
 import Link from "next/link";
+import { pageCount } from "@/lib/pagination";
 
 export function Pagination({
   page,
@@ -13,7 +14,7 @@ export function Pagination({
   basePath: string; // e.g. "/page" or "/search"
   query?: string; // extra query string without leading ?
 }) {
-  const pages = Math.max(1, Math.ceil(total / pageSize));
+  const pages = pageCount(total, pageSize);
   if (pages <= 1) return null;
   const mk = (p: number) => {
     if (basePath === "/page") return p <= 1 ? `/` : `/page/${p}`;

apps/web/lib/pagination.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { normalizePage } from "./pagination";
+import { normalizePage, pageCount } from "./pagination";
 
 describe("normalizePage", () => {
   it("accepts positive numeric page values", () => {
@@ -24,3 +24,14 @@ describe("normalizePage", () => {
     expect(normalizePage("-2")).toBe(1);
   });
 });
+
+describe("pageCount", () => {
+  it("keeps an empty feed on its first page", () => {
+    expect(pageCount(0, 24)).toBe(1);
+  });
+
+  it("rounds partial pages up", () => {
+    expect(pageCount(24, 24)).toBe(1);
+    expect(pageCount(25, 24)).toBe(2);
+  });
+});

apps/web/lib/pagination.ts

@@ -5,6 +5,10 @@ export function normalizePage(value: unknown, fallback = 1): number {
   return parsed >= 1 ? parsed : fallback;
 }
 
+export function pageCount(total: number, pageSize: number): number {
+  return Math.max(1, Math.ceil(total / pageSize));
+}
+
 export function parsePageInteger(value: unknown): number | null {
   if (typeof value === "number") {
     return Number.isSafeInteger(value) ? value : null;