feat(cms): install Payload and serve the admin panel

Payload 3.88 runs inside the Next app against the existing Postgres, in
its own 'payload' schema so no pipeline operation on public — the app
tables, Airflow's metadata, migrate_csv_to_db.py --drop — can reach blog
content.

Its REST API is mounted at /cms-api. /api is the FastAPI proxy's
catch-all, which would swallow every admin call and forward it to the
backend with no error. The mount points live in lib/payloadRoutes.ts so
there is one definition and a test can assert it without importing
Payload: it is ESM-only, next/jest will not transform it, and appending
transformIgnorePatterns cannot un-ignore a package. Forcing it through
transpilePackages would change how the production build bundles Payload
to serve a test, so the live proof that /api still reaches FastAPI stays
where it belongs — the e2e journeys, which call /api/schools.

The package becomes ESM ("type": "module"), which Payload's CLI requires:
richtext-lexical has top-level await and the config cannot be require()d.
Only two files needed renaming, jest.config.cjs and a build script.

The build is verified to succeed with DATABASE_URL and PAYLOAD_SECRET
both unset, which is how CI builds it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017YmbBhr8s7GusjDE12hrZM

nextjs-app/.gitignore

@@ -39,3 +39,6 @@ yarn-error.log*
 # typescript
 *.tsbuildinfo
 next-env.d.ts
+
+# Payload generates this from the config on every build
+/payload-types.ts

nextjs-app/__tests__/payload/routes.test.ts

@@ -0,0 +1,45 @@
+/**
+ * Guards the one thing about Payload's mounting that fails silently.
+ *
+ * payload.config.ts itself cannot be imported here — Payload is ESM-only and
+ * next/jest will not transform it — so this asserts the shared constants and
+ * that the config actually wires them in, by reading its source. The live
+ * proof that /api still reaches FastAPI is the e2e journeys, which call
+ * /api/schools against the running app.
+ */
+import fs from 'fs';
+import path from 'path';
+import { PAYLOAD_API_ROUTE, PAYLOAD_ADMIN_ROUTE } from '@/lib/payloadRoutes';
+
+const CONFIG = fs.readFileSync(
+  path.join(__dirname, '..', '..', 'payload.config.ts'),
+  'utf8',
+);
+
+describe('payload mount points', () => {
+  it('serves the CMS API from /cms-api, never /api', () => {
+    // /api is the FastAPI proxy's catch-all. Payload's default would be
+    // swallowed by it and forwarded to the backend, silently.
+    expect(PAYLOAD_API_ROUTE).toBe('/cms-api');
+    expect(PAYLOAD_API_ROUTE).not.toBe('/api');
+  });
+
+  it('serves the admin panel from /admin', () => {
+    expect(PAYLOAD_ADMIN_ROUTE).toBe('/admin');
+  });
+
+  it('wires both constants into the Payload config', () => {
+    expect(CONFIG).toContain('PAYLOAD_API_ROUTE');
+    expect(CONFIG).toContain('PAYLOAD_ADMIN_ROUTE');
+  });
+
+  it('never hardcodes a routes block that could drift from the constants', () => {
+    expect(CONFIG).not.toMatch(/routes:\s*\{[^}]*api:\s*['"]/);
+  });
+
+  it('isolates CMS tables in their own postgres schema', () => {
+    // Blog content must sit outside `public`, where the app tables, Airflow's
+    // metadata and scripts/migrate_csv_to_db.py --drop all live.
+    expect(CONFIG).toMatch(/schemaName:\s*['"]payload['"]/);
+  });
+});

nextjs-app/app/(payload)/admin/[[...segments]]/not-found.tsx

@@ -0,0 +1,16 @@
+import type { Metadata } from 'next';
+import config from '@payload-config';
+import { NotFoundPage, generatePageMetadata } from '@payloadcms/next/views';
+import { importMap } from '../importMap.js';
+
+type Args = {
+  params: Promise<{ segments: string[] }>;
+  searchParams: Promise<{ [key: string]: string | string[] }>;
+};
+
+export const generateMetadata = ({ params, searchParams }: Args): Promise<Metadata> =>
+  generatePageMetadata({ config, params, searchParams });
+
+export default function NotFound({ params, searchParams }: Args) {
+  return NotFoundPage({ config, importMap, params, searchParams });
+}

nextjs-app/app/(payload)/admin/[[...segments]]/page.tsx

@@ -0,0 +1,16 @@
+import type { Metadata } from 'next';
+import config from '@payload-config';
+import { RootPage, generatePageMetadata } from '@payloadcms/next/views';
+import { importMap } from '../importMap.js';
+
+type Args = {
+  params: Promise<{ segments: string[] }>;
+  searchParams: Promise<{ [key: string]: string | string[] }>;
+};
+
+export const generateMetadata = ({ params, searchParams }: Args): Promise<Metadata> =>
+  generatePageMetadata({ config, params, searchParams });
+
+export default function Page({ params, searchParams }: Args) {
+  return RootPage({ config, importMap, params, searchParams });
+}

nextjs-app/app/(payload)/admin/importMap.js

@@ -0,0 +1,6 @@
+import { CollectionCards as CollectionCards_f9c02e79a4aed9a3924487c0cd4cafb1 } from '@payloadcms/next/rsc'
+
+/** @type import('payload').ImportMap */
+export const importMap = {
+  "@payloadcms/next/rsc#CollectionCards": CollectionCards_f9c02e79a4aed9a3924487c0cd4cafb1
+}

nextjs-app/app/(payload)/cms-api/[...slug]/route.ts

@@ -0,0 +1,20 @@
+/*
+ * Payload's REST API, mounted at /cms-api rather than /api.
+ * See lib/payloadRoutes.ts — /api is the FastAPI proxy's catch-all.
+ */
+import config from '@payload-config';
+import {
+  REST_DELETE,
+  REST_GET,
+  REST_OPTIONS,
+  REST_PATCH,
+  REST_POST,
+  REST_PUT,
+} from '@payloadcms/next/routes';
+
+export const GET = REST_GET(config);
+export const POST = REST_POST(config);
+export const DELETE = REST_DELETE(config);
+export const PATCH = REST_PATCH(config);
+export const PUT = REST_PUT(config);
+export const OPTIONS = REST_OPTIONS(config);

nextjs-app/app/(payload)/cms-api/graphql-playground/route.ts

@@ -0,0 +1,4 @@
+import config from '@payload-config';
+import { GRAPHQL_PLAYGROUND_GET } from '@payloadcms/next/routes';
+
+export const GET = GRAPHQL_PLAYGROUND_GET(config);

nextjs-app/app/(payload)/cms-api/graphql/route.ts

@@ -0,0 +1,5 @@
+import config from '@payload-config';
+import { GRAPHQL_POST, REST_OPTIONS } from '@payloadcms/next/routes';
+
+export const POST = GRAPHQL_POST(config);
+export const OPTIONS = REST_OPTIONS(config);

nextjs-app/app/(payload)/layout.tsx

@@ -0,0 +1,27 @@
+/**
+ * Root layout for the Payload admin panel.
+ *
+ * This is a SECOND root layout: it renders its own <html>/<body>, as does
+ * app/(frontend)/layout.tsx. Next permits that only while no app/layout.tsx
+ * exists — which is why the site's routes were moved into (frontend). Adding
+ * an app/layout.tsx would nest the admin panel inside the site's nav, footer
+ * and providers and emit nested <html>.
+ */
+import type { ServerFunctionClient } from 'payload';
+import config from '@payload-config';
+import { RootLayout, handleServerFunctions } from '@payloadcms/next/layouts';
+import { importMap } from './admin/importMap.js';
+import '@payloadcms/next/css';
+
+const serverFunction: ServerFunctionClient = async function (args) {
+  'use server';
+  return handleServerFunctions({ ...args, config, importMap });
+};
+
+export default function PayloadLayout({ children }: { children: React.ReactNode }) {
+  return (
+    <RootLayout config={config} importMap={importMap} serverFunction={serverFunction}>
+      {children}
+    </RootLayout>
+  );
+}

nextjs-app/collections/Users.ts

@@ -0,0 +1,33 @@
+import type { CollectionConfig } from 'payload';
+
+/**
+ * The site's only authenticated surface. There is one account and no
+ * registration: `create` is closed to everyone, so the first user is seeded
+ * with `payload create-first-user` and no one can add another through the API.
+ */
+export const Users: CollectionConfig = {
+  slug: 'users',
+  auth: {
+    // Slows credential stuffing against a panel that is on the public
+    // internet. Five attempts, then a ten-minute lock.
+    maxLoginAttempts: 5,
+    lockTime: 10 * 60 * 1000,
+  },
+  access: {
+    create: () => false,
+    read: ({ req }) => Boolean(req.user),
+    update: ({ req }) => Boolean(req.user),
+    delete: () => false,
+  },
+  admin: { useAsTitle: 'email' },
+  fields: [
+    {
+      name: 'displayName',
+      type: 'text',
+      required: true,
+      // Rendered as the byline on every post. First name only — the site
+      // publishes no surname and no employer.
+      defaultValue: 'Tudor',
+    },
+  ],
+};

nextjs-app/lib/payload.ts

@@ -0,0 +1,15 @@
+import { getPayload } from 'payload';
+import config from '@payload-config';
+import type { Payload } from 'payload';
+
+/**
+ * One Payload instance per process. getPayload() is itself memoised by
+ * Payload, but routing every caller through here keeps the config import in a
+ * single place and gives page code one name to mock in tests.
+ *
+ * Never call this at module scope: CI builds the image with no database
+ * reachable, so a build-time connection attempt fails the build.
+ */
+export function getCachedPayload(): Promise<Payload> {
+  return getPayload({ config });
+}

nextjs-app/lib/payloadRoutes.ts

@@ -0,0 +1,23 @@
+/**
+ * Where Payload mounts, defined once.
+ *
+ * These are imported by payload.config.ts and asserted by
+ * __tests__/payload/routes.test.ts. They live in their own module because
+ * payload.config.ts cannot be imported from a Jest test: Payload ships
+ * ESM-only, and next/jest's transformIgnorePatterns skips node_modules — you
+ * cannot un-ignore a package by appending patterns, and forcing it through
+ * `transpilePackages` would change how the production build bundles Payload
+ * to serve a test. Keeping the values here makes them testable without
+ * loading Payload at all.
+ */
+
+/**
+ * Payload's API base. It must NOT be '/api': that path belongs to
+ * app/(frontend)/api/[...path]/route.ts, a catch-all that proxies to FastAPI.
+ * It would swallow every admin API call and forward it to the backend, and
+ * the failure is silent — no error, just wrong responses.
+ */
+export const PAYLOAD_API_ROUTE = '/cms-api';
+
+/** The admin panel. Kept out of the index by robots.txt and X-Robots-Tag. */
+export const PAYLOAD_ADMIN_ROUTE = '/admin';

nextjs-app/next.config.mjs

@@ -1,3 +1,5 @@
+import { withPayload } from '@payloadcms/next/withPayload';
+
 /** @type {import('next').NextConfig} */
 const nextConfig = {
   // Enable standalone output for Docker
@@ -127,4 +129,4 @@ const nextConfig = {
   },
 };
 
-export default nextConfig;
+export default withPayload(nextConfig);

nextjs-app/package.json

@@ -2,6 +2,7 @@
   "name": "nextjs-app",
   "version": "0.1.0",
   "private": true,
+  "type": "module",
   "description": "SchoolCompare Next.js Application",
   "scripts": {
     "dev": "next dev",
@@ -14,18 +15,24 @@
   },
   "dependencies": {
     "@floating-ui/react": "^0.27.20",
+    "@payloadcms/db-postgres": "^3.88.0",
+    "@payloadcms/next": "^3.88.0",
+    "@payloadcms/richtext-lexical": "^3.88.0",
     "@types/node": "^25.2.0",
     "@types/react": "^19.2.10",
     "@types/react-dom": "^19.2.3",
     "chart.js": "^4.5.1",
     "eslint": "^9.39.2",
     "eslint-config-next": "^16.1.6",
+    "graphql": "^16.14.2",
     "leaflet": "^1.9.4",
     "next": "^16.1.6",
+    "payload": "^3.88.0",
     "react": "^19.2.4",
     "react-chartjs-2": "^5.3.1",
     "react-dom": "^19.2.4",
     "react-leaflet": "^5.0.0",
+    "sharp": "^0.35.4",
     "typescript": "^5.9.3",
     "zod": "^4.3.6"
   },
@@ -36,7 +43,6 @@
     "@types/jest": "^30.0.0",
     "@types/leaflet": "^1.9.21",
     "jest": "^30.2.0",
-    "jest-environment-jsdom": "^30.2.0",
+    "jest-environment-jsdom": "^30.2.0"
-    "sharp": "^0.34.5"
   }
 }

nextjs-app/payload.config.ts

@@ -0,0 +1,30 @@
+import path from 'path';
+import { fileURLToPath } from 'url';
+import { buildConfig } from 'payload';
+import { postgresAdapter } from '@payloadcms/db-postgres';
+import { lexicalEditor } from '@payloadcms/richtext-lexical';
+import sharp from 'sharp';
+import { Users } from '@/collections/Users';
+import { PAYLOAD_API_ROUTE, PAYLOAD_ADMIN_ROUTE } from '@/lib/payloadRoutes';
+
+const filename = fileURLToPath(import.meta.url);
+const dirname = path.dirname(filename);
+
+export default buildConfig({
+  admin: { user: Users.slug },
+  // Defined in lib/payloadRoutes.ts, which carries the reasoning and is what
+  // the test asserts. Never inline these — /api belongs to the FastAPI proxy.
+  routes: { api: PAYLOAD_API_ROUTE, admin: PAYLOAD_ADMIN_ROUTE },
+  collections: [Users],
+  editor: lexicalEditor(),
+  secret: process.env.PAYLOAD_SECRET || '',
+  typescript: { outputFile: path.resolve(dirname, 'payload-types.ts') },
+  db: postgresAdapter({
+    pool: { connectionString: process.env.DATABASE_URL },
+    // Its own schema, so no pipeline operation on `public` can reach blog
+    // content. scripts/migrate_csv_to_db.py --drop lives in that blast radius,
+    // as does Airflow's metadata.
+    schemaName: 'payload',
+  }),
+  sharp,
+});

nextjs-app/tsconfig.json

@@ -25,6 +25,9 @@
     "paths": {
       "@/*": [
         "./*"
+      ],
+      "@payload-config": [
+        "./payload.config.ts"
       ]
     }
   },