> For clean Markdown of any page, append .md to the page URL. > For a complete documentation index, see https://contentful.com/developers/docs/llms.txt. > For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://contentful.com/_mcp/server. # Integrate the Optimization Next.js SDK in a Next.js App Router app ## Overview Use this guide to render a personalized Contentful entry on the server and keep the same result when the browser starts. The server gives the browser a plain-data snapshot of the selected variants and browser startup settings used for that render. This snapshot is an Optimization handoff. **New to personalization?** Here is the breakdown of how it works: * In Contentful you author **variants** of an entry and attach them to an **experience** — a rule that decides which visitors see which variant. * When a page is requested, Contentful's **Experience API** looks at the current visitor and picks the variant for each experience. Swapping a fetched entry for its picked variant is called **resolving** the entry. * Your app hands a Contentful entry to the SDK at the point where that entry becomes output. The SDK gives back the selected variant, or the original entry when no variant applies—the **baseline fallback**. You can fetch the entry yourself or give the SDK your Contentful client and an entry ID; either way, the client stays yours. * You render the returned entry with the same application components you already use. That is enough to start. The guide introduces policy and optional capabilities at the point you need them. You will get there in two milestones: * **Milestone 1 — Personalized first paint from one server render.** The quick start below is shippable when your policy allows server personalization. * **Milestone 2 — Browser takeover and live updates.** See [Browser takeover and live updates](#browser-takeover-and-live-updates). This guide uses `@contentful/optimization-nextjs/app-router/server` for Server Components and `@contentful/optimization-nextjs/app-router/client` when an app needs bound Client Components. The adapter binds app-local configured components and handoff helpers; your app still owns Contentful client credentials and query policy, the choice between app-owned and SDK-managed entry fetching, consent policy, and any keys or policy for your application's rendered-output caches. The SDK owns its managed-entry cache and request synchronization. If you use the Pages Router, use the If your app uses the App Router, use the [Next.js App Router guide](/personalization/optimization-sdk/integrate-the-optimization-sdk-in-a-nextjs-app-router-app/) instead. ## Quick start This quick start assumes an App Router route already fetches a Contentful entry and renders it with your own component. The proof is one entry whose variant appears in View Source and stays stable after hydration. Consent is granted on the server and browser only to prove the wiring; replace it in [Consent, identity, profile, and reset](#consent-identity-profile-and-reset). Before starting, attach a variant to that entry through an experience that targets all visitors. Without an authored variant, a working integration still renders the baseline and cannot prove the personalization path. 1. Install the package and keep `contentful` app-owned. **Copy this:** ```sh pnpm add @contentful/optimization-nextjs contentful ``` 2. Add the Optimization project values to your app's browser-visible environment file. Find the client ID and environment in the Contentful web app under **Apps → Installed apps → Contentful Personalization → SDK keys**. The variable names and `.env.local` placement below are app-owned; keep the `NEXT_PUBLIC_` prefix because the browser binding needs these values. **Adapt this to your use case:** ```dotenv # .env.local NEXT_PUBLIC_OPTIMIZATION_CLIENT_ID=your-client-id NEXT_PUBLIC_CONTENTFUL_ENVIRONMENT=main ``` 3. Bind one app-local server Optimization module. This binding shares one configured helper set for the app. Its nested `optimization.request` family initializes the active request before any request-bound component renders. Use the same Contentful environment for server and client binding code. The consent values below are a quick-start policy shortcut: `server.events` and `clientDefaults.consent` allow personalization events, while `server.persistence` and `clientDefaults.persistenceConsent` allow the SDK-owned anonymous ID to persist. The `preserve-server` hydration mode tells the browser to keep the server-rendered result while its live runtime starts. **Adapt this to your use case:** ```tsx // lib/optimization.ts import { bindNextjsAppRouterServerOptimization } from '@contentful/optimization-nextjs/app-router/server' import { contentfulClient } from './contentful' export const optimization = bindNextjsAppRouterServerOptimization({ clientId: process.env.NEXT_PUBLIC_OPTIMIZATION_CLIENT_ID!, environment: process.env.NEXT_PUBLIC_CONTENTFUL_ENVIRONMENT ?? 'main', locale: 'en-US', contentful: { client: contentfulClient }, consent: { server: { events: true, persistence: true }, clientDefaults: { consent: true, persistenceConsent: true }, }, request: { hydration: 'preserve-server' }, }) export const { NextAppAutoPageTracker: RequestNextAppAutoPageTracker, OptimizationRoot: RequestOptimizationRoot, OptimizedEntry: RequestOptimizedEntry, } = optimization.request ``` 4. Forward the original request URL so the request family can initialize. Use the handler name for your Next.js version: Next.js 16 uses `proxy.ts` with `proxy`, and Next.js 13 to 15 uses `middleware.ts` with `middleware`. The body is the same. If the filename or export name does not match the Next.js version, Next.js does not run the handler and request context is not forwarded. The SDK handler owns the forwarded request-header names and values. The matcher paths below are app-owned and cover the participating route families in the maintained App Router shape. Keep the matcher narrow when your route names differ. **Adapt this to your use case:** ```ts // Next.js 16: proxy.ts and export const proxy. // Next.js 13 to 15: middleware.ts and export const middleware. import { createNextjsOptimizationContextHandler } from '@contentful/optimization-nextjs/request-handler' const optimizationRequestHandler = createNextjsOptimizationContextHandler() export const proxy = optimizationRequestHandler // In Next.js 13 to 15, export this as middleware instead. export const config = { matcher: [ '/', '/page-two', '/hidden-until-ready', '/static-shell-private-slot', '/selection-handoff/:path*', '/analytics-only/:path*', ], } ``` 5. Split your shell into three responsibilities before adding the request root: * `AppShellChrome` renders request-independent navigation and keeps normal Next.js `Link` prefetch enabled. * `AppShellBody` contains UI that reads the Optimization provider. * `PersonalizedContentFallback` gives the private region a labeled loading state without hiding the public navigation. These names are app-owned. Map the responsibilities onto your existing shell rather than adding a second shell. **Adapt this to your use case:** ```tsx // components/AppShell.tsx import Link from 'next/link' import type { ReactNode } from 'react' export function AppShellChrome({ children }: { children: ReactNode }) { return (
{children}
) } export function AppShellBody({ children }: { children: ReactNode }) { return
{children}
} export function PersonalizedContentFallback() { return (

Loading personalized page content…

) } ``` 6. Wrap the request-dependent part of the route in the nested request root. Keep public, request-independent chrome outside both the root and `Suspense`. Put the page tracker and every component that reads the Optimization provider inside the root. The meaningful fallback keeps public navigation available while private content loads. On Next.js 15 and later with Cache Components, `connection()` marks the private slot as request-time work; keep its import and call at that boundary so the public shell remains separate from visitor-specific rendering. On Next.js 13 to 14, omit the import and call because that API is unavailable. The surrounding layout is illustrative context to match against, not a full file to paste over your layout. **Adapt this to your use case:** ```diff // app/(request)/layout.tsx +import { + AppShellBody, + AppShellChrome, + PersonalizedContentFallback, +} from '../../../../components/AppShell' +// Next.js 15+ with Cache Components. Omit this import on Next.js 13 to 14. +import { connection } from 'next/server' +import { Suspense } from 'react' +import { RequestNextAppAutoPageTracker, RequestOptimizationRoot } from '../../../../lib/optimization' +async function PrivateRequestSlot({ children }: { children: React.ReactNode }) { + // Next.js 15+ with Cache Components. Omit this call on Next.js 13 to 14. + await connection() + + return ( + + + {children} + + ) +} + export default function RequestLayout({ children }: { children: React.ReactNode }) { return ( - {children} + + }> + {children} + + ) } ``` 7. Wrap the entry where it becomes output. A **render prop** is the function child `{(entry) => ...}`; it lets you render the resolved entry with your existing component. This shortcut assumes the baseline and every eligible variant use the `hero` content type. If a variant can use another content type, follow the skeleton-union and narrowing path in [Personalizing first paint on the server](#personalizing-first-paint-on-the-server). **Adapt this to your use case:** ```diff // app/(request)/page.tsx +import { RequestOptimizedEntry } from '../../../../lib/optimization' import { Hero } from '../../../../components/Hero' export default async function Page() { const hero = await getHeroEntry({ locale: 'en-US', include: 10 }) return ( - + + {(resolvedHero) => } + ) } ``` 8. Verify the result. In Contentful, target the experience to all visitors and give the variant a distinctive text value. Run the app, open View Source, and find that variant text in the raw HTML. Then load the page normally and confirm the same text remains after hydration. ## Before you start The sections below walk the integration in order. First, gather the few things you can only get from outside this guide: * A Next.js App Router app with React Server Components, React, and React DOM already working. * A Contentful delivery client that can fetch the baseline entries your pages render. * Contentful space, environment, delivery token, and one concrete locale. Fetch entries with that locale and enough `include` depth for linked Optimization entries and variants. * **At least one entry with a variant attached to an experience**, authored in Contentful. Without an authored variant, the integration can still run correctly while returning the baseline, so you cannot yet distinguish working personalization from a content-authoring gap. For the first personalized-content test, target all visitors so the test request or visitor matches automatically. * **Your Optimization project values** — client ID and environment, from your Optimization project settings. Find them in the Contentful web app under **Apps → Installed apps → Contentful Personalization → SDK keys**. This guide stores them in `NEXT_PUBLIC_OPTIMIZATION_CLIENT_ID` and `NEXT_PUBLIC_CONTENTFUL_ENVIRONMENT`. The client ID and environment are safe to expose to the browser, and both bindings must use the same values. The Experience and Insights API base URLs default correctly; you only set them for mocks or non-default hosts (see [How the SDK fits your app](#how-the-sdk-fits-your-app)). You do not need a setup inventory up front. Everything else — the request handler, the root, entry wrapping, consent, tracking — is introduced by the section that needs it. > \[!NOTE] > > Match your app's browser environment-variable convention. Next.js exposes `NEXT_PUBLIC_*` values > to the browser; unprefixed server values stay server-only. ## Core integration ### How the SDK fits your app **Integration category:** Required for first integration The App Router server and client bindings centralize SDK configuration for route code. Define each binding once in its own runtime-specific module. A binding creates reusable configured components; the nested `optimization.request` family keeps each visitor request's work and state separate. The quick start uses only the server binding and request handler. The remaining paths support the advanced route strategies taught later: | Import path | Use | | ----------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `@contentful/optimization-nextjs/app-router/server` | Server binding; its nested `request` components personalize per visitor. Top-level roots accept app-supplied handoffs; the entry consumes its documented props and stored handoff state, while the tracker consumes its documented event-ownership prop | | `@contentful/optimization-nextjs/app-router/client` | A configured component family for Client Components | | `@contentful/optimization-nextjs/cache-middleware` | Rewrites routes for app-defined personalization choices that are safe to share publicly | | `@contentful/optimization-nextjs/client` | Browser hooks, providers, and entry controls | | `@contentful/optimization-nextjs/edge` | Request and handoff helpers for the Edge runtime | | `@contentful/optimization-nextjs/request-handler` | Forwards the request URL and, in advanced trusted flows, compact server context | | `@contentful/optimization-nextjs/tracking-attributes` | Adds tracking attributes when the browser tracks server-rendered markup without re-resolving it | The package root is not an import path. Server Components use the server binding. A **bound Client Component** uses components created by the client binding rather than importing a router-neutral component directly. Create that separate binding only when a bound Client Component needs one; router-neutral hooks and per-entry browser controls continue to use `/client`. **Adapt this to your use case:** keep browser-only binding code in a Client Component module, and match the server binding's public configuration values. ```tsx // lib/optimization-client.ts 'use client' import { bindNextjsAppRouterClientOptimization } from '@contentful/optimization-nextjs/app-router/client' export const clientOptimization = bindNextjsAppRouterClientOptimization({ clientId: process.env.NEXT_PUBLIC_OPTIMIZATION_CLIENT_ID!, environment: process.env.NEXT_PUBLIC_CONTENTFUL_ENVIRONMENT ?? 'main', locale: 'en-US', }) ``` The binding config separates policy from mechanism: * `consent.server` is the app-owned server policy for the current request; configure it explicitly because App Router request initialization resolves omitted request consent to `false`. * `consent.clientDefaults` seeds the browser SDK before a persisted or explicit browser decision is available. * `contentful.client` is your delivery client. The SDK may call it for managed entry IDs or content-type/slug lookups, but it does not own your Contentful Delivery API (CDA) credentials or query policy. ### Choose who owns entry fetching **Integration category:** Required for first integration Choose one of these supported workflows for each entry: * **App-owned fetching:** Keep your existing fetcher, query, and cache, then pass its result as `baselineEntry`. This fits apps that already coordinate Contentful data with other page data. * **SDK-managed fetching:** Give the binding your `contentful.js` client, then identify the entry by `entryId` or by a `managedEntry` descriptor. This fits entries whose Contentful Delivery API (CDA) work can be owned by the Optimization SDK. App-owned fetching is the quick-start workflow. The app fetches first, and the request entry resolves that baseline with the request's experience-and-variant choices. **Adapt this to your use case:** ```tsx import { RequestOptimizedEntry } from '../../../../lib/optimization' import { contentfulClient } from '../../../../lib/contentful' export async function AppOwnedHero({ entryId }: { entryId: string }) { const baselineEntry = await contentfulClient.getEntry(entryId, { include: 10, locale: 'en-US', }) return ( {(entry) =>

{String(entry.fields.headline)}

} ) } ``` For a content-type-and-slug lookup, pass the object under the fixed `managedEntry` prop. The `contentType`, `slug`, optional `slugField`, and optional `entryQuery` property names are SDK-defined; their values come from your route and content model. `slugField` defaults to `slug`. **Adapt this to your use case:** ```tsx import { RequestOptimizedEntry } from '../../../../lib/optimization' export function ManagedHeroBySlug({ slug }: { slug: string }) { const managedEntry = { contentType: 'hero', slug, entryQuery: { include: 10, locale: 'en-US' }, } as const return ( {(entry) =>

{String(entry.fields.headline)}

} ) } ``` The SDK-managed ID workflow below shows the deltas to the existing quick-start binding and private slot. The binding supplies the app-owned client, the request root prefetches the baseline into the browser handoff, and the request entry resolves that same ID for server output. `entryId` is an app-owned Contentful entry ID. Edit the existing binding and root; do not create a second binding or nest another root around an already-bound subtree. The server-only `CONTENTFUL_HERO_ENTRY_ID` name and value in this example are app-owned. **Adapt this to your use case:** ```diff // lib/optimization.ts - the existing binding import { contentfulClient } from './contentful' export const optimization = bindNextjsAppRouterServerOptimization({ // Keep the existing client ID, environment, locale, and consent. contentful: { client: contentfulClient }, }) // app/(request)/layout.tsx - the existing private slot +import { RequestOptimizedEntry } from '../../../../lib/optimization' -async function PrivateRequestSlot({ children }: { children: React.ReactNode }) { +async function PrivateRequestSlot({ + children, + entryId, +}: { + children: React.ReactNode + entryId: string +}) { // Next.js 15+ with Cache Components. Omit this call and its import on Next.js 13 to 14. await connection() return ( - + + + {(entry) =>

{String(entry.fields.headline)}

} + {children} ) } export default function RequestLayout({ children }: { children: React.ReactNode }) { + const entryId = process.env.CONTENTFUL_HERO_ENTRY_ID! return ( }> - {children} + {children} ) } ``` Mount this private slot under the public chrome and `Suspense` composition from the quick start. For SDK-managed entries, the SDK starts baseline fetching or root prefetch alongside request initialization. A request entry waits for its baseline and request's experience-and-variant choices before resolving. A request root waits for its prefetch and request handoff before merging the fetched entries once. Both paths use the SDK's managed cache and in-flight deduplication. Do not add a duplicate await, request cache, or performance option around these components. App-owned CDA fetches remain app-owned work, so they do not receive this direct request/CDA overlap. Both workflows require one concrete locale and enough `include` depth for the linked experience and variant entries. All-locale CDA payloads can make those links look unresolved and fall back to the baseline. ### Request context and the profile cookie **Integration category:** Common but policy-dependent Every `optimization.request` component uses one SDK-owned initializer for the active React Server Component request. The initializer reads Next.js headers and cookies, requires the request URL forwarded by the Optimization handler, and derives these values once: * The **route key**, the current route identity used to prevent duplicate page tracking. * The **initial page payload**, the page properties attached to the first page event. * The **hydration mode**, the browser startup rule that preserves or hides server content. * The **private-request handoff**, the experience-and-variant choices and startup data for this visitor's request. The app does not read those inputs or coordinate layout and page awaits. Separate requests receive separate initialization and handoff state. Use the no-argument `createNextjsOptimizationContextHandler()` from the quick start for the default forwarding-only path. It sanitizes SDK-owned forwarded context and supplies the request URL header; the request family performs request evaluation. Keep the matcher narrow to the routes that use Optimization request context. Trusted response-capable request persistence is an advanced opt-in for routes whose proxy or middleware must perform the page request and persist the SDK-owned anonymous ID cookie before Server Components render. See [Manual server and client escape hatches](#manual-server-and-client-escape-hatches). The SDK-owned anonymous ID cookie is `ctfl-opt-aid`. It stores the identifier that connects browser and server activity. A **profile** is the Experience API's current visitor ID, traits, audiences, and session state; the cookie is not that full profile, selected state, or consent record. Your app owns any consent cookie or account record that `consent.server` reads. Store the consent decision where both server and browser code can read it; do not use the SDK anonymous ID cookie as your consent record. ### Personalizing first paint on the server **Integration category:** Required for first integration Server Components render personalized first paint through `optimization.request.OptimizedEntry`. If no experience applies, the API has no variant, or a linked variant cannot be resolved, the render receives the baseline entry. When policy denies the selection-producing Experience API request, no **selected optimizations** enter the request state. Selected optimizations are the experience-and-variant choices returned by an accepted page, identify, or custom Experience event. Resolution without a selection also returns the baseline. `isEmptyVariant === true` marks the SDK renderer's no-content state. It differs from the fallback cases above, which render the baseline entry. In the no-content state, the bound server `OptimizedEntry` keeps its host and tracking attributes but does not invoke its render prop or emit app content. The standalone `ServerOptimizedEntry`, imported from `@contentful/optimization-nextjs/server`, is the lower-level renderer for server code that already has a full resolver result and static children; it applies the same empty-content rule. An absent empty-variant flag renders normally. A resolved selected variant can use any Contentful content type. The request entry waits for the same initialization as the request root, including when page work begins before its layout work. For an SDK-managed source, baseline fetching starts alongside that initialization. Resolution remains behind both the baseline and selected request state, so the entry never resolves against partial request data. A Contentful **entry skeleton** is a TypeScript type that names a content type ID and its fields. Use one skeleton union, `S`, containing every possible baseline or variant content type. A bound server `OptimizedEntry` with `baselineEntry` uses ``, where `M` is the `contentful.js` response-shape modifier carried by the entry type and `L` is the locale type. A managed ID or slug source uses `` because its response-shape modifier is fixed to `undefined`. When every variant shares the baseline content type, omit the generic and let TypeScript infer that skeleton from `baselineEntry`. **Follow this pattern:** declare the complete skeleton union in the Server Component and narrow in the render prop, where the resolved entry becomes page markup. The guard compares the Contentful content type ID; it does not validate fields. ```tsx import { RequestOptimizedEntry } from '../../../../lib/optimization' import { isEntryOfContentType } from '@contentful/optimization-nextjs/api-schemas' import type { Entry, EntryFieldTypes, EntrySkeletonType } from 'contentful' type PageSkeleton = EntrySkeletonType<{ title: EntryFieldTypes.Symbol }, 'page'> type HeroSkeleton = EntrySkeletonType<{ headline: EntryFieldTypes.Symbol }, 'hero'> type CtaSkeleton = EntrySkeletonType<{ label: EntryFieldTypes.Symbol }, 'cta'> type AppEntrySkeleton = PageSkeleton | HeroSkeleton | CtaSkeleton type AppLocale = 'en-US' export function PersonalizedPage({ page }: { page: Entry }) { return ( baselineEntry={page}> {(entry) => { if (isEntryOfContentType(entry, 'hero')) { return

{entry.fields.headline}

} if (isEntryOfContentType(entry, 'cta')) { return } return

{entry.fields.title}

}} ) } ``` The union is a compile-time model, not a runtime filter. Narrow at the renderer boundary before reading content-type-specific fields. For lower-level resolver, managed-fetch, open-ended model, and event-stream examples, see [TypeScript content-model choices](/personalization/optimization-sdk/entry-personalization-and-variant-resolution#typescript-content-model-choices). The request family reads the active Next.js request, so Next.js renders that subtree for each request instead of reusing one public static result. Keep that visitor-specific output out of public shared caches. For shareable static or public-permutation routes, use the advanced route strategies in [Route-level SSR, browser takeover, and browser-owned islands](#route-level-ssr-browser-takeover-and-browser-owned-islands). ### The bound root and page events **Integration category:** Required for first integration Use `optimization.request.OptimizationRoot` at a private request route root. It gives the browser provider the server snapshot and browser startup mode. The request `NextAppAutoPageTracker` also learns whether the server accepted the initial page-view event: it skips a duplicate when the server owns that event, then tracks later client navigations. The request family builds the route key and page payload, so the app does not pass either one. Keep the tracker inside the Next.js-required `Suspense` boundary; that boundary is a platform rendering requirement, not request-initialization plumbing. Keep request-independent public chrome outside both `Suspense` and the request root. Put the tracker, provider-dependent shell body, and all other SDK-dependent UI inside the root. Use a meaningful fallback for the private slot so the public navigation and page context remain available while it loads. Keep Next.js `Link` prefetch enabled; the narrow handler matcher limits request-context work to participating routes. Advanced explicit-input routes can pass an app-created handoff and browser startup mode to the top-level `optimization.OptimizationRoot` or `optimization.OptimizationProvider`. The root can also take an app-created route key and initial page payload. `initialPageEvent` is the handoff field that tells a browser tracker to `skip` a server-owned first page event or `emit` a browser-owned one. See [Manual server and client escape hatches](#manual-server-and-client-escape-hatches) before using these inputs. Use `optimization.OptimizationAnalyticsRoot` for analytics-only handoffs. If you pass `prefetchManagedEntries` without an explicit `handoff`, the App Router root creates baseline `static` handoff behavior with `hydration: 'preserve-server'`, no selected optimizations, and `initialPageEvent: 'emit'`. Use that path for baseline managed-entry warming, not request-personalized state. Mount one development-only observer inside the request root before validating events elsewhere in this guide. The accepted stream holds the most recent accepted event as its current value, not an event history. The blocked stream reports events rejected by consent or event policy. **Adapt this to your use case:** ```tsx // components/OptimizationEventDiagnostics.tsx 'use client' import { useOptimizationContext } from '@contentful/optimization-nextjs/client' import { useEffect } from 'react' export function OptimizationEventDiagnostics() { const { isLive, sdk } = useOptimizationContext() useEffect(() => { if (process.env.NODE_ENV !== 'development' || isLive !== true || sdk === undefined) return const accepted = sdk.states.eventStream.subscribe((event) => { if (event) console.debug('Contentful Optimization event accepted', event) }) const blocked = sdk.states.blockedEventStream.subscribe((event) => { if (event) console.debug('Contentful Optimization event blocked', event) }) return () => { accepted.unsubscribe() blocked.unsubscribe() } }, [isLive, sdk]) return null } ``` **Adapt this to your use case:** ```diff // app/(request)/layout.tsx +import { OptimizationEventDiagnostics } from '../../../../components/OptimizationEventDiagnostics' + {children} ``` The observer mounts in the browser after the root publishes its live SDK. Its accepted stream is a local signal that the browser SDK admitted an event; it does not prove that a server event ran or that either API received an event. Use three separate checks: * **Server render:** Use the quick-start View Source check to prove that the selected variant reached the raw server HTML. * **Browser admission:** Trigger a tracked action and inspect the browser console for `Contentful Optimization event accepted` or `Contentful Optimization event blocked`. * **Duplicate page prevention:** Clear the browser console and reload the route. Hydration must not log a browser `page` event when the server accepted the first page event. Follow a normal Next.js `Link` to another participating route and confirm one browser `page` event appears for that navigation. To verify API delivery rather than local admission, inspect your server's outbound Experience API telemetry for the initial request and your browser Network panel for browser-owned events. The browser observer cannot see the completed server call. ### Browser takeover and live updates **Integration category:** Required for first integration The handoff controls the first browser render over already-rendered content. `liveUpdates` controls whether entries may re-resolve after startup when consent, identity, profile, or preview state changes. Use the default locked behavior for stable first paint. Turn on `liveUpdates` in the binding config only when the participating tree must react after hydration. For per-entry browser control, use the router-neutral `/client` `OptimizedEntry`; the bound App Router entry does not accept per-entry `liveUpdates` or `loadingFallback`. The preview panel can force live re-resolution for authoring even when the normal route keeps live updates off. For one observable live-update check, author an experience whose audience requires the trait `plan = "pro"`. Give its variant distinctive **Pro** text and leave the baseline with distinctive **Control** text. `HeroEntry` below is your app's existing single-locale Contentful entry type. The request root owns the live browser SDK; this Client Component consumes that provider and opts this entry into re-resolution. **Adapt this to your use case:** ```tsx // components/LiveHero.tsx 'use client' import type { HeroEntry } from '@/lib/contentful' import { OptimizedEntry, useOptimizationActions } from '@contentful/optimization-nextjs/client' export function LiveHero({ baselineEntry }: { baselineEntry: HeroEntry }) { const { identifyUser, resetUser } = useOptimizationActions() return (
{(entry) => {String(entry.fields.headline)}}
) } ``` Mount `LiveHero` under the existing `RequestOptimizationRoot`. Load the route as an anonymous visitor and confirm **Control** appears. Click **Identify as Pro** and confirm the same output changes to **Pro** without a reload. Click **Reset visitor** and confirm it returns to **Control**. These changes belong to the browser runtime; the server-rendered first paint remains the request's locked snapshot. For a top-level explicit-input route, pass `hydration="client-only-hidden-until-ready"` to `optimization.OptimizationRoot` or `optimization.OptimizationProvider`, or build that mode into the handoff. For a nested private-request route, set this mode in the server binding's `request` configuration. A fully browser-owned route instead uses the router-neutral `/client` `OptimizationRoot` or `OptimizationProvider`. Hidden-until-ready hydration is independent of the private-slot composition. Use it only when the content itself must remain hidden until the browser runtime is ready; it is not needed to keep public chrome outside a request boundary. ### Entry interaction tracking **Integration category:** Common but policy-dependent `OptimizedEntry` emits view, click, and hover tracking from the resolved entry by default. Configure global defaults with `trackEntryInteraction` in the binding config and use per-entry props for local opt-outs. Interaction delivery still depends on event consent and profile continuity. The binding-level object controls the three interaction kinds for every entry. `clickable` marks one entry wrapper as a click target; `trackViews`, `trackClicks`, and `trackHovers` override the matching setting for one entry. **Adapt this to your use case:** ```diff // lib/optimization.ts - existing binding export const optimization = bindNextjsAppRouterServerOptimization({ // Existing project, Contentful, and consent config. + trackEntryInteraction: { views: true, clicks: true, hovers: true }, }) // Existing entry renderer - + {(entry) => } ``` Keep the development observer from [The bound root and page events](#the-bound-root-and-page-events) mounted. Scroll the entry into view, hover over its wrapper, and click it. The browser console must show locally accepted `component`, `component_hover`, and `component_click` event types, or a blocked record that names the denied method. This check proves local browser admission, not API receipt. Analytics-only server/static/edge markup imports `getServerTrackingAttributes()` from `@contentful/optimization-nextjs/tracking-attributes` so the browser analytics runtime observes the same `data-ctfl-*` contract without resolving content. ### Consent, identity, profile, and reset **Integration category:** Common but policy-dependent Replace the quick-start consent shortcut with your app policy: 1. Read the app-owned consent record in `consent.server`; omitted request consent resolves to `false`. 2. Seed conservative browser defaults through `consent.clientDefaults`. 3. Mirror browser choices to the app-owned consent record before the next request. 4. Use `setConsent`, `identifyUser`, and `resetUser` from `/client` hooks for browser actions. `setConsent(true)` or `setConsent(false)` sets both event consent and persistence consent to the same value. Use the object form, `setConsent({ events, persistence })`, when those two decisions differ. **Adapt this to your use case:** ```tsx bindNextjsAppRouterServerOptimization({ clientId: process.env.NEXT_PUBLIC_OPTIMIZATION_CLIENT_ID!, environment: process.env.NEXT_PUBLIC_CONTENTFUL_ENVIRONMENT ?? 'main', consent: { server: ({ cookies }) => cookies.get('app-consent')?.value === 'accepted' ? { events: true, persistence: true } : false, clientDefaults: { consent: false, persistenceConsent: false }, }, }) ``` `app-consent` is reader-owned in this example. The SDK reads only the decision you pass to it. Mount one app-owned control inside `RequestOptimizationRoot` so the browser action path updates the same record that `consent.server` reads on the next request. This minimal example uses a browser-readable cookie; replace `writeAppConsent` with your consent-management platform or server endpoint when that system owns the record. **Adapt this to your use case:** ```tsx // components/OptimizationVisitorControls.tsx 'use client' import { useConsentState, useOptimizationActions, useProfileState, } from '@contentful/optimization-nextjs/client' function writeAppConsent(value: 'accepted' | 'denied') { const secure = window.location.protocol === 'https:' ? '; Secure' : '' document.cookie = `app-consent=${value}; Path=/; SameSite=Lax; Max-Age=31536000${secure}` } export function OptimizationVisitorControls() { const consent = useConsentState() const profile = useProfileState() const { identifyUser, resetUser, setConsent } = useOptimizationActions() function accept() { writeAppConsent('accepted') setConsent(true) } function withdraw() { writeAppConsent('denied') setConsent(false) resetUser() } return (
Consent: {String(consent)} Visitor: {profile?.id ?? 'anonymous'}
) } ``` Your app owns the `app-consent` record, account mapping, and any consent-management cleanup. The SDK owns its profile state, selected optimizations, local continuity, and `ctfl-opt-aid` cookie. `setConsent(false)` clears SDK durable storage but leaves the active in-memory profile, so withdrawal also calls `resetUser()`. Resetting alone preserves consent and does not erase your app's record. ## Optional integrations ### Analytics forwarding **Integration category:** Optional `onStatesReady` is the binding callback that receives the live browser SDK's observable state surface before child auto-page effects run. `states.eventStream` exposes the most recent locally accepted event and later accepted events; it is not a durable history. Each event's `messageId` is its unique delivery identifier. The optional `event.optimization` field is stream-only attribution, and its `resolvedEntry` is the Contentful entry selected for that interaction. Its `sys.id` is that selected entry's ID, which the example passes downstream as `resolvedEntryId`. The runtime event stream remains model-agnostic because it can carry interactions for entries of every content type. If you read `event.optimization?.resolvedEntry`, narrow that entry with `isEntryOfContentType` at the point of use; resolver-specific `S` types do not flow into a later event. The following seam gates forwarding on a separate app-owned analytics consent record, deduplicates the current-value stream by `messageId`, unsubscribes on root teardown, and contains vendor failures. Replace the cookie and endpoint with your analytics platform's policy and transport. **Adapt this to your use case:** ```ts // lib/optimization-event-forwarding.ts import type { OnStatesReady } from '@contentful/optimization-nextjs/client' function hasAnalyticsConsent() { return document.cookie.split('; ').includes('analytics-consent=accepted') } async function forwardToAnalytics(event: { messageId: string type: string resolvedEntryId?: string }) { const response = await fetch('/api/analytics-events', { body: JSON.stringify(event), headers: { 'content-type': 'application/json' }, method: 'POST', }) if (!response.ok) throw new Error(`Analytics forwarding failed: ${response.status}`) } export const forwardOptimizationEvents: OnStatesReady = (states) => { const forwardedMessageIds = new Set() const subscription = states.eventStream.subscribe((event) => { if (!event || !hasAnalyticsConsent() || forwardedMessageIds.has(event.messageId)) return forwardedMessageIds.add(event.messageId) void forwardToAnalytics({ messageId: event.messageId, type: event.type, resolvedEntryId: event.optimization?.resolvedEntry.sys.id, }).catch((error: unknown) => { console.warn('Optimization analytics forwarding failed', error) }) }) return () => { subscription.unsubscribe() forwardedMessageIds.clear() } } ``` Add `onStatesReady: forwardOptimizationEvents` to the existing binding that owns the participating browser root. Do not create a second binding or provider for forwarding. Keep `states.blockedEventStream` for diagnostics; blocked calls are not events to replay. **Adapt this to your use case:** ```diff // lib/optimization.ts - existing binding +import { forwardOptimizationEvents } from './optimization-event-forwarding' export const optimization = bindNextjsAppRouterServerOptimization({ // Existing project, Contentful, and consent config. + onStatesReady: forwardOptimizationEvents, }) ``` For the full pattern, use [Forwarding Optimization SDK context to analytics and tag-management tools](/personalization/optimization-sdk/forwarding-optimization-sdk-context-to-analytics-and-tag-management-tools/). ### Merge tags and Custom Flags **Integration category:** Optional A **merge tag** is an SDK-authored embedded entry whose selector reads one value from the current visitor profile and falls back to its authored fallback text. Your app owns the Rich Text renderer and must extract the embedded target before asking the SDK to resolve it. The request-family `OptimizedEntry` supplies `getMergeTagValue` as the second render-prop argument. `ArticleEntry` below is your app's existing entry type. **Adapt this to your use case:** ```tsx // components/RichText.tsx import { isMergeTagEntry, type MergeTagEntry } from '@contentful/optimization-nextjs/api-schemas' import { documentToReactComponents } from '@contentful/rich-text-react-renderer' import { INLINES, type Document } from '@contentful/rich-text-types' type GetMergeTagValue = (entry: MergeTagEntry) => string | undefined export function RichText({ document, getMergeTagValue, }: { document: Document getMergeTagValue: GetMergeTagValue }) { return documentToReactComponents(document, { renderNode: { [INLINES.EMBEDDED_ENTRY]: (node) => { const target: unknown = node.data.target return isMergeTagEntry(target) ? (getMergeTagValue(target) ?? '') : '' }, }, }) } ``` Pass the resolver from the request entry into that renderer. **Adapt this to your use case:** ```tsx // components/PersonalizedArticle.tsx import { RichText } from '../../../../components/RichText' import type { ArticleEntry } from '@/lib/contentful' import { RequestOptimizedEntry } from '../../../../lib/optimization' export function PersonalizedArticle({ article }: { article: ArticleEntry }) { return ( {(entry, { getMergeTagValue }) => ( )} ) } ``` In a Client Component that already sits under an Optimization provider, `useMergeTagResolver()` supplies the same resolver without an entry render prop. **Adapt this to your use case:** ```tsx 'use client' import { useMergeTagResolver } from '@contentful/optimization-nextjs/client' import type { Document } from '@contentful/rich-text-types' import { RichText } from '../../../../components/RichText' export function LiveRichText({ document }: { document: Document }) { const { getMergeTagValue } = useMergeTagResolver() return } ``` A **Custom Flag** is an authored name/value change rather than a replacement entry. The flag name is chosen in your Contentful Personalization experience. The SDK's `states.flag(name)` observable emits its current value immediately and later values after accepted profile or preview changes. **Adapt this to your use case:** ```tsx // components/CheckoutFlag.tsx 'use client' import { useOptimizationContext } from '@contentful/optimization-nextjs/client' import { useEffect, useState } from 'react' export function CheckoutFlag() { const { sdk } = useOptimizationContext() const [value, setValue] = useState() useEffect(() => { if (!sdk) return const subscription = sdk.states.flag('checkout-banner').subscribe(setValue) return () => subscription.unsubscribe() }, [sdk]) return {String(value ?? 'unset')} } ``` Author `checkout-banner` with two distinguishable values, mount this component under the existing request root, then change the matching visitor state or force a value in the preview panel. Confirm the output changes. See [Contentful personalization authoring](https://www.contentful.com/developers/docs/personalization/) and [Custom Flags authoring](https://www.contentful.com/help/personalization/experiences/custom-flags/). ### Preview panel **Integration category:** Optional Attach `@contentful/optimization-web-preview-panel` only in development, preview, or staging environments. The panel needs the live browser SDK and a Contentful client or pre-fetched audience and experience entries. Keep the environment gate app-owned; do not ship editor tooling to ordinary production visitors. **Copy this:** ```sh pnpm add @contentful/optimization-web-preview-panel ``` The example below uses `NEXT_PUBLIC_OPTIMIZATION_ENABLE_PREVIEW_PANEL` as an app-owned environment gate and `contentfulClient` as an app-owned browser-safe Contentful client. Wait for `isLive` before attaching; its earlier SDK value is the read-only handoff snapshot. The owned browser root registers the live SDK that the panel uses by default. **Adapt this to your use case:** ```tsx // components/OptimizationPreviewPanel.tsx 'use client' import { contentfulClient } from '../../../../lib/contentful-client' import { useOptimizationContext } from '@contentful/optimization-nextjs/client' import { useEffect } from 'react' export function OptimizationPreviewPanel() { const { error, isLive, sdk } = useOptimizationContext() const enabled = process.env.NEXT_PUBLIC_OPTIMIZATION_ENABLE_PREVIEW_PANEL === 'true' useEffect(() => { if (!enabled || isLive !== true || sdk === undefined) return void import('@contentful/optimization-web-preview-panel') .then(({ default: attachOptimizationPreviewPanel }) => attachOptimizationPreviewPanel({ contentful: contentfulClient }), ) .catch((previewError: unknown) => { console.warn('Contentful Optimization preview panel failed to attach', previewError) }) }, [enabled, isLive, sdk]) if (!enabled) return null if (error) return

Optimization preview failed to initialize.

return ( {isLive ? 'Optimization preview ready' : 'Optimization preview initializing'} ) } ``` Mount the panel inside the same request root as the content it previews. **Adapt this to your use case:** ```diff // app/(request)/layout.tsx +import { OptimizationPreviewPanel } from '../../../../components/OptimizationPreviewPanel' + {children} ``` In a non-production environment, enable the gate, load the route, and wait for **Optimization preview ready**. Open the panel, force the authored variant, and confirm that the rendered entry changes. If attachment fails, the browser console shows the error. When the app already fetched the panel's audience and experience entries, pass `entries` instead of `contentful`. ## Advanced integrations ### Route-level SSR, browser takeover, and browser-owned islands **Integration category:** Advanced or production-only Choose one ownership model per route: | Route strategy | First paint owner | Browser content behavior | Cache scope | | ------------------------------ | ----------------------------------------------------------------------------- | ----------------------------------------------------------- | --------------------------------------- | | Nested request components | Server request | Preserves server output; optional live updates | `private-request` | | Public permutation handoff | Static generation, Cache Components, or Edge runtime route chosen by app code | Preserves selected output; optional live updates | `public-permutation` with SDK-built key | | Analytics-only handoff | Server, static, or Edge runtime markup | Tracks page and interactions only; no content re-resolution | Matches the rendered markup owner | | Client-only hidden-until-ready | Browser SDK | Hides baseline until ready or timeout | Static page shell | For request-personalized routes, prefer a private-slot composition. Keep public navigation and other request-independent chrome outside the request root and `Suspense`. Give the private slot a meaningful fallback, then place the provider-dependent shell body and every SDK-dependent component inside the request root. In a Next.js 15 or later app that uses Cache Components, put revalidation policy in the cached component with `use cache`, `cacheLife()`, and `cacheTag()`. Call `connection()` inside the private slot to keep that boundary on the request-time side of the composition. In Next.js 13 to 14, omit the `connection()` import and call because that API is unavailable. The request family creates its visitor-specific `private-request` handoff automatically; the app does not pass that cache scope to the nested request root. **Adapt this to your use case:** ```ts // next.config.ts import type { NextConfig } from 'next' const nextConfig: NextConfig = { cacheComponents: true, } export default nextConfig ``` **Follow this pattern:** ```tsx // app/static-shell-private-slot/page.tsx import { AppShellChrome, PersonalizedContentFallback } from '../../../../components/AppShell' import { cacheLife, cacheTag } from 'next/cache' import { Suspense } from 'react' import { PrivateRequestSlot } from './PrivateRequestSlot' async function CachedMarketingShell() { 'use cache' cacheLife('minutes') cacheTag('static-marketing-shell') return } export default function Page() { return ( }> ) } ``` **Follow this pattern:** ```tsx // app/static-shell-private-slot/PrivateRequestSlot.tsx import { AppShellBody } from '../../../../components/AppShell' import { RequestNextAppAutoPageTracker, RequestOptimizationRoot } from '../../../../lib/optimization' // Next.js 15+ with Cache Components. Omit this import on Next.js 13 to 14. import { connection } from 'next/server' export async function PrivateRequestSlot() { // Next.js 15+ with Cache Components. Omit this call on Next.js 13 to 14. await connection() return ( ) } ``` `AppShellChrome`, `AppShellBody`, `PersonalizedContentFallback`, `StaticMarketingShell`, and `PersonalizedPrivateContent` are app-owned components in this pattern. `AppShellChrome` can contain normal Next.js `Link` components with their default prefetch behavior. The `static-marketing-shell` cache tag is app-owned. Cache Components do not use route-level `export const revalidate`; put ISR-style revalidation on the cached component or data function instead. If your app is not using Cache Components, do not copy the partial private-slot seam above. Use the complete [SSG baseline with browser-owned personalization](/personalization/optimization-sdk/render-personalized-nextjs-routes#ssg-baseline-with-browser-owned-personalization) recipe instead. For complete SSG, App Router Cache Components, Pages Router ISR, Edge runtime, and analytics-only recipes, use [Rendering personalized Next.js routes with static, ISR, and edge handoffs](/personalization/optimization-sdk/rendering-personalized-nextjs-routes/). For the mechanics behind handoff state and cache scopes, use [Optimization handoff and cache-safe rendering](/personalization/optimization-sdk/optimization-handoff-and-cache-safe-rendering/). ### Manual server and client escape hatches **Integration category:** Advanced or production-only Use lower-level subpaths only when the bound App Router module cannot express the route. The main escape hatches are: * `/server` for direct Node request control with `configureNextjsServerOptimization(...)`. That helper configures a stateless server runtime; it is not a request-isolation context. * The top-level `optimization.createRequestHandoff(...)` from the `/app-router/server` binding when advanced orchestration already owns explicit request, hydration, page payload, and handoff inputs. * `/app-router/client` for a bound App Router Client Component family. * `/client` for router-neutral React roots, providers, and hooks. * `/tracking-attributes` for manually rendered analytics-only markup. * `/edge` for Edge runtime route handlers that export `runtime = 'edge'` and avoid Node-only APIs. Manual flows still pass `handoff` to a React root. Do not invent a second state shape for browser hydration. Keep `createRequestHandoff()` out of the normal private-request route; the nested request family owns that work. The response-capable handler is also an advanced opt-in. Configure `createNextjsOptimizationContextHandler(...)` with a server SDK and consent resolver, then set `request.trustedRequestHandoff: true` on the App Router binding. That pair allows the request family to trust compact server context forwarded by the handler. Keep the no-argument forwarding-only handler for ordinary request-family routes. Lower-level resolver calls keep selections as the optional second positional argument: `resolveOptimizedEntry(entry, selectedOptimizations)`. Managed fetch calls accept an ID or a source object shaped as `{ contentType, slug, slugField?, entryQuery? }`. The ID overload receives its query in `FetchOptimizedEntryOptions`; the slug source object carries `entryQuery` itself. `ServerOptimizedEntry` places the element type first, followed by the complete skeleton union, response mode, and locale. When lower-level code renders a resolver result directly, `isEmptyVariant === true` marks the SDK renderer's no-content state; check it before rendering `entry`. The result retains the baseline entry and selection context for tracking even when consumer output is empty. ### Caching and request deduplication **Integration category:** Advanced or production-only `private-request` handoffs include one visitor's request state and must not be stored in a shared public cache. `public-permutation` handoffs are for app-owned segments, campaigns, markets, or other choices that are safe to share. Their main inputs are: * `selectedOptimizations`: The app-supplied list of experience-and-variant choices to render. * `changes`: The app-supplied Custom Flag name/value changes to hydrate. * `permutationKey`: An app-owned stable name for the public segment or campaign. * `cacheVersion`: An optional app-owned version token that changes the generated cache identity when the rendered rules change. Pass those values, plus the locale and rendered entry IDs, to `createPublicPermutationHandoff()`. The helper serializes the supplied state and creates public cache metadata; it does not discover a segment or derive selected optimizations from a route, cookie, header, locale, or cache key. Because `changes` are handoff state rather than part of the generated cache-key fingerprint, rotate `cacheVersion` when rendered Custom Flag values change. `static` handoffs are for baseline or build-time output that does not depend on a request profile. Do not create public or static handoffs from request-derived profile state. Use the supplemental rendering guide for static generation, App Router Cache Components, Pages Router ISR, Edge runtime, and analytics-only recipes. Use the handoff concept when reviewing whether a route can be public, public-permutation, static, or private-request cached. Within one React Server Component request, every `optimization.request` wrapper shares one SDK-owned initialization. Managed entries use the SDK's managed cache and in-flight deduplication. Their baseline fetch or root prefetch starts alongside request initialization. A request entry waits for its baseline and selected request state before resolving; a request root waits for prefetch and request state before merging the fetched entries into the handoff once. Separate requests remain isolated. These responsibilities are different from caching rendered output. Do not add an app-owned React request cache, request shell, duplicate layout/page await, or performance setting around the request family. Validate visitor isolation with two browser profiles whose consent or identity selects different authored text. Use View Source in each profile and confirm profile A receives only variant A while profile B receives only variant B. Reload both profiles and repeat the check. A value crossing between profiles means visitor-specific HTML entered a shared output cache; it is not an SDK managed entry-cache hit. ### Strict consent and duplicate-event controls **Integration category:** Advanced or production-only When no Optimization event may emit before explicit consent, configure a strict event policy and return `false` from `consent.server` until your app-owned consent record is accepted. The request tracker receives first-page-event ownership from its handoff. For top-level explicit handoff flows, use `initialPageEvent="skip"` only when a server or edge helper already accepted the same route's first page event. Use blocked-event diagnostics to verify denied events are dropped at the SDK boundary. `allowedEventTypes` is the binding's pre-consent event allow-list. An empty list makes every event require accepted event consent. **Adapt this to your use case:** ```diff // lib/optimization.ts - existing binding export const optimization = bindNextjsAppRouterServerOptimization({ // Existing project and Contentful config. + allowedEventTypes: [], consent: { server: ({ cookies }) => cookies.get('app-consent')?.value === 'accepted', clientDefaults: { consent: false, persistenceConsent: false }, }, }) ``` Keep `OptimizationEventDiagnostics` mounted before `RequestNextAppAutoPageTracker`. Clear the `app-consent` cookie, reload, and confirm the browser console reports a blocked record whose `reason` is `consent` and whose `method` is `page`. Click **Allow personalization** in the control shown earlier, then follow a normal Next.js `Link` to another participating route. Confirm that the resulting navigation produces a locally accepted `page` event. If the server accepted the first page event on a later request, the handoff tells the browser tracker to skip that duplicate. Consent withdrawal has separate owners: record denial in your app or consent-management platform, call `setConsent(false)` to stop and clear SDK durable event storage, and call `resetUser()` to clear the active SDK profile and selected optimizations. The SDK does not erase the app-owned consent or account record. ## Production checks * Confirm server and browser config use the intended Contentful space, environment, locale, and Optimization client ID. * Confirm `consent.server`, browser consent defaults, and app-owned consent storage agree. * Confirm `ctfl-opt-aid` is browser-readable where server and browser profile continuity is needed. * Confirm locally accepted server and browser events arrive at the intended Experience or Insights API destination; the browser diagnostic alone is not delivery evidence. * Confirm server page events are not duplicated by browser route trackers. * Confirm baseline fallback is acceptable when no variant applies or Contentful links are unresolved. * Confirm request-personalized output is never stored in a public shared cache. * Run your app's existing typecheck, lint, production build, and browser E2E scripts. Script names are app-owned; use the commands already declared in your app's `package.json`. * Compare the result with the maintained App Router reference implementation's [local run instructions](https://github.com/contentful/optimization/blob/main/implementations/nextjs-sdk_app-router/README.md#running-locally) and [E2E instructions](https://github.com/contentful/optimization/blob/main/implementations/nextjs-sdk_app-router/README.md#running-e2e-tests). The following commands run the reference implementation from this monorepo; they are not commands to copy into an unrelated application. **Reference excerpt:** ```sh pnpm setup:e2e:nextjs-sdk_app_router pnpm test:e2e:nextjs-sdk_app_router ``` ## Troubleshooting | Symptom | Likely cause | Check | | --------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Entries stay on baseline | No matching variant, no selections after a blocked Experience event, unresolved variant links, or all-locale CDA payload | Target all visitors for the first test, read accepted or blocked events, and fetch one locale with enough `include` depth | | A heterogeneous render cannot read content-type-specific fields | The skeleton union omits a possible content type, or the entry was not narrowed before rendering | Include every baseline and variant skeleton in `S`, then narrow with `isEntryOfContentType` | | Variant appears in the browser but not View Source | The route is browser-owned rather than request-family or public-permutation rendered | Use `optimization.request` for private request rendering, or use a top-level public permutation handoff before rendering | | Request components report a missing forwarded request URL | The handler filename or export name does not match the Next.js version, or the handler is absent | Configure the SDK request handler; use `proxy.ts` with `proxy` on Next.js 16, or `middleware.ts` with `middleware` on Next.js 13 to 15 | | Duplicate first page events | A top-level explicit root and route tracker both emitted the initial route | Give the top-level tracker the handoff's `initialPageEvent`; the request-family tracker receives it automatically | | Live entries do not change after identify or reset | The entry is locked to the handoff and live updates are off | Set `liveUpdates: true` on the App Router binding or use `/client` `LiveUpdatesProvider` for a browser subtree; for one entry, use router-neutral `/client` `OptimizedEntry liveUpdates` because bound App Router entries have no per-entry `liveUpdates` prop | | Personalized HTML is cached for the wrong visitor | Request handoff output entered a public cache | Use `private-request` for request state and public permutation handoffs only for app-owned selected permutations | ## Reference implementations to compare against * [Next.js SDK Pages Router reference implementation](https://github.com/contentful/optimization/tree/main/implementations/nextjs-sdk_pages-router/README.md): Working Pages Router application using `getServerSideProps` state handoff, app-local bound components, client takeover, live updates, consent controls, page events, entry interaction tracking, preview attachment, and Playwright E2E coverage. * [Next.js SDK App Router reference implementation](https://github.com/contentful/optimization/tree/main/implementations/nextjs-sdk_app-router/README.md): App Router equivalent using bound Server and Client Component exports.