1,000,000 \times 0.02\text{s} = 20,000\text{ seconds} \approx \mathbf{5.5\text{ hours of continuous build time!}}

+-----------------------------------------------------------------------------------------+
|                  Modern Next.js 15 Programmatic SEO (pSEO) Architecture                 |
+-----------------------------------------------------------------------------------------+

[Googlebot / User Requests /cost/fintech-app-in-mumbai]
                          |
                          v
+-----------------------------------------------------------------+
| Cloudflare / Vercel Edge CDN Cache Lookup                       |
+-----------------------------------------------------------------+
          |                                       |
   (Cache Hit: 25ms TTFB)                  (Cache Miss / First Visit)
          |                                       |
          v                                       v
[Serve Static Cached HTML]             [On-Demand Server Component Render]
                                                  |
                                                  v (Queries PostgreSQL Read Replica <5ms)
                                       [Render Rich Page with Structured Data & Calculators]
                                                  |
                                                  v
                                       [Cache at Edge CDN with 'revalidate: 86400']

// app/sitemap.ts (or app/sitemap/[id]/route.ts)
import { MetadataRoute } from "next";
import db from "@/lib/db";

const URLS_PER_SITEMAP = 40000; // Safe threshold under Google's 50k limit

// 1. Generate Sitemap IDs (e.g., [ { id: 0 }, { id: 1 }, ... { id: 24 } ])
export async function generateSitemaps() {
  const totalPages = await db.getPseoPagesCount();
  const numberOfSitemaps = Math.ceil(totalPages / URLS_PER_SITEMAP);

  return Array.from({ length: numberOfSitemaps }, (_, i) => ({ id: i }));
}

// 2. Render each sharded sitemap dynamically based on ID
export default async function sitemap({ id }: { id: number }): Promise<MetadataRoute.Sitemap> {
  const offset = id * URLS_PER_SITEMAP;
  const pages = await db.getPseoPagesBatch({ limit: URLS_PER_SITEMAP, offset });

  return pages.map((page) => ({
    url: `https://mojostudio.in/cost/${page.slug}`,
    lastModified: page.updatedAt,
    changeFrequency: "weekly" as const,
    priority: 0.8,
  }));
}

// app/cost/[slug]/page.tsx
import { Metadata } from "next";
import db from "@/lib/db";
import { notFound } from "next/navigation";

// 1. Dynamic SEO Metadata Generation
export async function generateMetadata({
  params,
}: {
  params: Promise<{ slug: string }>;
}): Promise<Metadata> {
  const { slug } = await params;
  const data = await db.getPseoPageData(slug);
  if (!data) return {};

  return {
    title: `How Much Does It Cost to Build a `{data.industry} App in `{data.city}? (2026 Guide)`,
    description: `Complete 2026 pricing breakdown for building a `{data.industry} application in `{data.city}. Hourly rates, development timelines, and compliance requirements.`,
    alternates: {
      canonical: `https://mojostudio.in/cost/${slug}`,
    },
    openGraph: {
      title: ``{data.industry} App Development Cost in `{data.city}`,
      description: `Comprehensive 2026 pricing analysis and tech stack guide for ${data.city} founders.`,
      url: `https://mojostudio.in/cost/${slug}`,
      siteName: "MojoStudio",
      type: "article",
    },
  };
}

// 2. Page Component with Injected JSON-LD Schema
export default async function ProgrammaticCostPage({
  params,
}: {
  params: Promise<{ slug: string }>;
}) {
  const { slug } = await params;
  const data = await db.getPseoPageData(slug);
  if (!data) notFound();

  // Schema.org FAQPage and Article JSON-LD
  const jsonLd = {
    "@context": "https://schema.org",
    "@type": "FAQPage",
    mainEntity: data.faqs.map((faq: any) => ({
      "@type": "Question",
      name: faq.question,
      acceptedAnswer: {
        "@type": "Answer",
        text: faq.answer,
      },
    })),
  };

  return (
    <>
      <script
        type="application/ld+json"
        dangerouslySetInnerHTML={{ __html: JSON.stringify(jsonLd) }}
      />
      <main className="max-w-4xl mx-auto px-4 py-12">
        <h1 className="text-4xl font-extrabold text-white">
          Cost to Build a {data.industry} App in {data.city} (2026 Breakdown)
        </h1>
        {/* Dynamic Calculator & Data Tables */}
      </main>
    </>
  );
}

// 3. Configure On-Demand ISR Caching
export const revalidate = 86400; // 24-hour edge cache revalidation

+-----------------------------------------------------------------------------------------+
|                  High-Authority Programmatic Page Content Anatomy                       |
+-----------------------------------------------------------------------------------------+
| [1. Localized Economic Data: Real developer hourly rates & average salaries in City X]  |
+-----------------------------------------------------------------------------------------+
| [2. Interactive Cost Estimator: Interactive client-side slider calculating custom MVP]  |
+-----------------------------------------------------------------------------------------+
| [3. Proprietary Industry Benchmarks: Architecture diagrams, tech stack comparisons]     |
+-----------------------------------------------------------------------------------------+
| [4. Structured Semantic FAQs: 8+ unique, Schema.org-indexed questions and answers]      |
+-----------------------------------------------------------------------------------------+
| [5. Breadcrumb & Hub-and-Spoke Internal Links: Contextual links to related silos]       |
+-----------------------------------------------------------------------------------------+

                              +-----------------------+
                              | Root Category Hub     |
                              | /cost/mobile-apps     |
                              +-----------+-----------+
                                          |
                     +--------------------+--------------------+
                     |                                         |
         +-----------v-----------+                 +-----------v-----------+
         | Industry Sub-Hub      |                 | Industry Sub-Hub      |
         | /cost/fintech         |                 | /cost/healthcare      |
         +-----------+-----------+                 +-----------+-----------+
                     |                                         |
         +-----------+-----------+                 +-----------+-----------+
         |                       |                 |                       |
+--------v-------+       +-------v--------+ +------v--------+       +------v--------+
| /cost/fintech- |       | /cost/fintech- | | /cost/health- |       | /cost/health- |
| in-mumbai      |       | in-bangalore   | | in-mumbai     |       | in-delhi      |
+----------------+       +----------------+ +---------------+       +---------------+