Agent-Skills.md

Agent Skills: OpenNext Cloudflare Adapter — Next.js on Workers

Deploy Next.js to Cloudflare Workers via OpenNext adapter. Use for SSR, ISR, App/Pages Router, or encountering worker size limits, runtime compatibility, connection scoping errors.

UncategorizedID: secondsky/claude-skills/cloudflare-nextjs

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secondsky/claude-skills
secondskyLicense: MIT
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pnpm dlx add-skill https://github.com/secondsky/claude-skills/tree/HEAD/plugins/cloudflare-nextjs/skills/cloudflare-nextjs

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plugins/cloudflare-nextjs/skills/cloudflare-nextjs/SKILL.md

Skill Metadata

Name
cloudflare-nextjs
Description
"Deploy Next.js to Cloudflare Workers via the OpenNext adapter (@opennextjs/cloudflare). Use for SSR/ISR/SSG/App or Pages Router, getCloudflareContext, bindings (D1/R2/KV/AI/Hyperdrive), caching tiers, skew protection, multi-worker, custom worker, env vars, or worker size/runtime/keep_names/FinalizationRegistry/connection-scoping errors."

OpenNext Cloudflare Adapter — Next.js on Workers

Deploy Next.js applications to Cloudflare Workers using the OpenNext adapter (@opennextjs/cloudflare). The adapter takes a standard Next.js build, runs package.json build script, then transforms the output to run on the Workers runtime using the Node.js compatibility layer (nodejs_compat) — not the Edge runtime.

Critical Requirements (get these wrong and the build/runtime fails)

| Requirement | Value | Why | |---|---|---| | Runtime | Node.js (default). Remove every export const runtime = "edge"; | Edge runtime is unsupported; OpenNext uses nodejs_compat. | | compatibility_flags | ["nodejs_compat", "global_fetch_strictly_public"] | Node APIs + allow fetch() in app code. | | compatibility_date | ≥ 2024-09-23; ≥ 2025-05-05 recommended (FinalizationRegistry) | Older dates break FinalizationRegistry, DOs, and more. | | Wrangler | ≥ 3.99.0 to deploy; ≥ 4.13.0 for keep_names; ≥ 4.36.0 for stable remote bindings | Feature gates in the docs. | | Next.js | v16 all minors/patches supported; latest minors of v14 and v15; v14 dropped Q1 2026 | Stated on the overview page. | | Worker size (gzip) | 3 MiB Free / 10 MiB Paid (compressed only) | Hard Cloudflare limits. |

Windows: not fully guaranteed (Next.js tooling issues). Use WSL, a Linux VM, or Linux/macOS CI. See known issue #1305.

Disambiguation: this skill vs nextjs

  • nextjs skill → framework/App Router/Server Components/Cache Components patterns, any platform (Vercel, self-hosted, ...). Use for async params, proxy.ts migration, "use cache".
  • THIS skill (cloudflare-nextjs) → deploying Next.js to Workers via the OpenNext adapter: wrangler.jsonc, open-next.config.ts, getCloudflareContext, caching tiers, bindings, skew protection, multi-worker, the Workers-specific errors.

proxy.ts caveat (Next 16): Next 16 renamed middleware.ts → proxy.ts, but @opennextjs/cloudflare does not recognize proxy.ts yet (issue #1277) — on Cloudflare, keep using middleware.ts. This is the one place the nextjs skill's guidance does NOT apply here.

Quick Start

New project (recommended)

npm create cloudflare@latest -- my-next-app --framework=next --platform=workers

C3 scaffolds a Next.js app, installs @opennextjs/cloudflare, creates wrangler.jsonc + open-next.config.ts + .dev.vars, wires package.json scripts, and (if R2 is enabled) creates an R2 bucket for caching.

Existing Next.js project (one command)

npx @opennextjs/cloudflare migrate

migrate automates: install adapter + wrangler, create wrangler.jsonc/open-next.config.ts/.dev.vars, update scripts, add public/_headers, add .open-next to .gitignore, wire initOpenNextCloudflareForDev() into next.config.ts, and create+configure an R2 cache bucket (only if R2 is enabled on the account).

<details><summary>Manual install (if you prefer not to run migrate)</summary> 
npm install @opennextjs/cloudflare@latest
npm install --save-dev wrangler@latest

Then create the three files (see references/wrangler.jsonc, references/open-next.config.ts, references/package.json) and add the dev/preview/deploy/upload/cf-typegen scripts. Pin adapter versions and audit before upgrading — see the dependency-upgrade skill.

</details>

The four scripts

// package.json
{
  "dev":     "next dev",                                                       // fast HMR via Next dev server
  "preview": "opennextjs-cloudflare build && opennextjs-cloudflare preview",   // build + run in workerd locally
  "deploy":  "opennextjs-cloudflare build && opennextjs-cloudflare deploy",    // build + serve immediately
  "upload":  "opennextjs-cloudflare build && opennextjs-cloudflare upload",    // build + upload a version (gradual rollout)
  "cf-typegen": "wrangler types --env-interface CloudflareEnv cloudflare-env.d.ts"
}
  • dev — fastest feedback loop; add initOpenNextCloudflareForDev() to next.config.ts so getCloudflareContext() works locally with simulated/remote bindings.
  • preview — runs in the actual Workers runtime (not Node). Always run before deploy to catch runtime-only issues.
  • deploy — populates the remote cache, then wrangler deploy. App serves immediately.
  • upload — populates remote cache, then wrangler versions upload. Does NOT serve automatically; for gradual deployments.

build, preview, deploy, upload all implicitly call populateCache — you do not need to run it manually.

Dev next.config.ts

import type { NextConfig } from "next";
const nextConfig: NextConfig = { /* ... */ };
export default nextConfig;

import { initOpenNextCloudflareForDev } from "@opennextjs/cloudflare";
initOpenNextCloudflareForDev();

Accessing Cloudflare Bindings — getCloudflareContext()

Do NOT use process.env for bindings. The official API is getCloudflareContext() from @opennextjs/cloudflare.

import { getCloudflareContext } from "@opennextjs/cloudflare";

export async function GET() {
  const { env, cf, ctx } = getCloudflareContext();
  await env.MY_KV.put("foo", "bar");
  return new Response(await env.MY_KV.get("foo"));
}

Static routes (ISR/SSG) MUST use async mode — and be careful: secrets/local values are used during static generation.

const { env } = await getCloudflareContext({ async: true });

TypeScript types: npm run cf-typegen generates cloudflare-env.d.ts (re-run after any binding change).

Remote bindings (local dev → real resources): stabilized in Wrangler 4.36.0. On older wrangler, enable via initOpenNextCloudflareForDev({ experimental: { remoteBindings: true } }) and use the experimental_remote (not remote) key on binding options. Note: remote bindings are also used during build.

Full patterns (D1/R2/KV/AI/Hyperdrive, Drizzle, Prisma, Stripe) → references/bindings-and-services.md.

Caching — three components, three tiers

OpenNext's cache has three parts: Incremental Cache (storage), Queue (dedupe/revalidate), Tag Cache (on-demand revalidateTag/revalidatePath).

| Site profile | Incremental | Queue | Tag Cache | When | |---|---|---|---|---| | SSG only (no revalidation) | staticAssetsIncrementalCache + enableCacheInterception: true | none | none | Fastest option; read-only | | Small site (ISR/on-demand) | r2IncrementalCache | doQueue | d1NextTagCache | Low traffic; D1 tag cache | | Large/high-traffic site | withRegionalCache(r2IncrementalCache, { mode: "long-lived" }) | doQueue | doShardedTagCache({ baseShardSize: 12 }) + purgeCache({ type: "direct" }) | DO-sharded; add cache purge if using on-demand |

Reserved binding names (do not reuse): ASSETS, WORKER_SELF_REFERENCE, NEXT_INC_CACHE_R2_BUCKET, NEXT_CACHE_DO_QUEUE, NEXT_TAG_CACHE_D1, NEXT_TAG_CACHE_DO_SHARDED, NEXT_CACHE_DO_PURGE, IMAGES.

  • Avoid Workers KV for incremental cache — eventually consistent, can persist stale data indefinitely.
  • Cache interception + PPR: incompatible today; cache interception is NOT enabled by default and does not work with PPR.
  • On-demand revalidation requires both a Tag Cache and the Cache Purge component (cache purge only works on a zone/custom domain; needs CACHE_PURGE_API_TOKEN + CACHE_PURGE_ZONE_ID secrets).
  • Pages Router res.revalidate requires a self-reference service binding named WORKER_SELF_REFERENCE.
  • Headers caveat: the Worker does not run in front of static assets, so next.config.ts headers() for public/ and immutable build files do not apply. Use public/_headers.

Deep dive (all options, env vars, regional modes, migration from 0.6) → references/caching.md and references/known-issues.md.

Common Integrations (condensed — full patterns in references)

  • Drizzle + D1/Hyperdrive/PG, Prisma + D1/PG/Hyperdrive — request-scoped clients via cache() from react; maxUses: 1 on PG pools; getCloudflareContext({ async: true }) for ISR/SSG; Prisma needs previewFeatures = ["driverAdapters"], no output dir in schema.prisma, and serverExternalPackages: ["@prisma/client", ".prisma/client"]. → references/bindings-and-services.md
  • Stripe — Workers have no node:https; pass httpClient: Stripe.createFetchHttpClient(). → references/bindings-and-services.md
  • Image optimization — images.binding: "IMAGES" in wrangler.jsonc, or a custom loader (/cdn-cgi/image/...) for zones. minimumCacheTTL and dangerouslyAllowLocalIP are not supported; custom loader bypasses middleware and ignores remotePatterns. → references/advanced.md
  • Env vars — use Next.js .env files (not just .dev.vars); NEXTJS_ENV in .dev.vars selects the env; --keep-vars on deploy; secrets are write-only. → references/dev-deploy-and-env.md
  • Custom worker (add scheduled, Durable Object exports) — point main at your worker that re-exports the generated fetch handler. → references/advanced.md
  • Multi-worker (split middleware from server) — reduces per-worker memory + cold starts; incompatible with preview URLs, skew protection, and @opennextjs/cloudflare deploy. → references/advanced.md
  • Skew protection (preview-URL-based version matching) — cloudflare.skewProtection.enabled, run_worker_first: true, getDeploymentId(), env vars CF_WORKER_NAME/CF_PREVIEW_DOMAIN/CF_WORKERS_SCRIPTS_API_TOKEN/CF_ACCOUNT_ID. Disabled for Workers with a Durable Object (move DOs to a separate worker). → references/advanced.md

Top Errors (full catalog → references/error-catalog-extended.md)

1. Worker size limit exceeded

"Your Worker exceeded the size limit of 3 MiB" (Free) / "10 MiB" (Paid). Only gzip size counts. Free → upgrade to Paid. Paid → analyze bundle: npx @opennextjs/cloudflare build, then inspect .open-next/server-functions/default/handler.mjs.meta.json (visualize with ESBuild Bundle Analyzer); remove unused deps, use dynamic imports.

2. Cannot perform I/O on behalf of a different request

Global DB client (e.g. postgres, pg Pool) reused across requests. Create the client inside the request handler (or use cache() from react), and maxUses: 1 for PG pools.

3. NPM package import / "Could not resolve <package>"

Enable nodejs_compat, ensure compatibility_date ≥ 2024-09-23. Some packages ship a workerd export — add them to serverExternalPackages in next.config.ts (e.g. @prisma/client, .prisma/client, postgres, jose, react-textarea-autosize, @libsql/isomorphic-ws). Or set .env: WRANGLER_BUILD_CONDITIONS="" + WRANGLER_BUILD_PLATFORM="node".

4. SSRF (CVE-2025-6087) — versions < 1.3.0

/_next/image SSRF. Upgrade immediately: @opennextjs/cloudflare@^1.3.0 (current: ^1.18.1).

5. Failed to load chunk server/chunks/ssr/<name>.js

Outdated adapter with Turbopack builds. Upgrade @opennextjs/cloudflare to latest, or switch to webpack (next build without --turbo).

6. ReferenceError: FinalizationRegistry is not defined

compatibility_date too old. Set "compatibility_date": "2025-05-05" (or later) in wrangler.jsonc.

7. Uncaught ReferenceError: __name is not defined

Wrangler's esbuild keep-names injects __name into generated script strings that some libs (e.g. next-themes) eval at runtime. Set "keep_names": false in wrangler.jsonc (requires Wrangler ≥ 4.13.0). You lose original function names in debugging.

8. "Failed to send request to R2 worker" / 403 during populateCache remote

Account protected by Cloudflare Access blocks the open-next-cache-populate helper worker. Do not create a separate Access app for it; add a Service Auth policy (Include = Any Access Service Token) to the existing app covering *.<account>.workers.dev, create a service token, and export CLOUDFLARE_ACCESS_CLIENT_ID / CLOUDFLARE_ACCESS_CLIENT_SECRET.

Known Open Bugs (live tracker)

Always check the issue tracker — these are recurring at the time of writing:

| # | Bug | Workaround | |---|---|---| | #1171 | v1.18.0 breaks R2 cache population (pinned) | Pin to 1.17.x or upgrade past the fix | | #1277 | proxy.js not supported — Next 16 proxy.ts rename breaks routing | Keep middleware.ts on Cloudflare | | #1130 / #1225 | cacheComponents: true crashes (Unexpected identifier '$' / Connection closed) | Disable cacheComponents | | #1321 | Intermittent React hydration mismatch (~9% of loads) | — | | #1322 / #1214 | Hyperdrive + pg / @prisma/adapter-pg bundling failure | — | | #1315 | Time-based fetch-cache revalidation silently no-ops on Next 16 (deployed) | — | | #1305 | Windows + Turbopack routes 500 | Use Linux/macOS or webpack | | #1317 | @cf-wasm/photon Turbopack build fails (raw .wasm) | Use webpack | | #1326 | Webpack chunk inlining misses named chunks → Unknown chunk N | — | | #617 | Node middleware (Next 15.2+) unsupported (feature request) | Use standard middleware |

Full tracker: https://github.com/opennextjs/opennextjs-cloudflare/issues

Feature Support

| Feature | Status | Notes | |---|---|---| | App Router, Pages Router, Route Handlers, Dynamic routes | ✅ | Full | | React Server Components, Server Actions | ✅ | Full | | SSG, SSR, ISR | ✅ | Full | | Middleware | ✅ | Except Node middleware (Next 15.2+, issue #617) | | Image optimization | ✅ | Via Cloudflare Images (binding or custom loader) | | Partial Prerendering (PPR) | ✅ | But cache interception + PPR incompatible today | | Composable Caching ('use cache'), after | ✅ | | | Turbopack | ✅ | But see #1305, #1317, #1326 — webpack is safer | | Edge Runtime | ❌ | Node runtime only; remove runtime = "edge" | | Node Middleware (15.2+) | ❌ | #617 |

Related Skills

| Skill | Use for | |---|---| | nextjs | Next.js framework/App Router patterns on any platform (the proxy.ts/cache/Server Components reference) | | cloudflare-workers | Generic Workers patterns; framework decision tree (Hono vs OpenNext) | | drizzle-orm-d1 | Drizzle + D1 deep dive (note: OpenNext must not bundle Wrangler — see its error catalog) | | cloudflare-r2 / cloudflare-kv / cloudflare-d1 | Service-specific deep dives | | dependency-upgrade | Pinning/auditing @opennextjs/cloudflare (production traffic) |

When to Load References

| File | Load when | |---|---| | references/caching.md | Choosing/configuring incremental/queue/tag cache, regional cache, cache purge | | references/bindings-and-services.md | Integrating D1/R2/KV/AI/Hyperdrive, Drizzle/Prisma request-scoped clients, Stripe | | references/dev-deploy-and-env.md | Setting up dev/preview/deploy, Workers Builds CI, env vars/secrets | | references/advanced.md | Custom worker, multi-worker, skew protection, static assets, keep_names, workerd packages, image optimization | | references/known-issues.md | DO build warnings, migrating 0.6 → 1.0.0-beta | | references/error-catalog-extended.md | Any error beyond the top 8 above | | references/troubleshooting.md | Step-by-step debugging + profiling/minification | | references/feature-support.md | Detailed feature compatibility matrix | | references/wrangler.jsonc | Small-site and large-site wrangler templates (all reserved bindings) | | references/open-next.config.ts | The three caching tiers as runnable configs | | references/database-client-example.ts | Request-scoped DB client patterns | | references/package.json | Reference scripts + versions |

Sources

  • Overview — https://opennext.js.org/cloudflare
  • Get started — https://opennext.js.org/cloudflare/get-started
  • CLI — https://opennext.js.org/cloudflare/cli
  • Bindings — https://opennext.js.org/cloudflare/bindings
  • Caching — https://opennext.js.org/cloudflare/caching
  • How-to: Stripe — https://opennext.js.org/cloudflare/howtos/stripeAPI
  • How-to: DB — https://opennext.js.org/cloudflare/howtos/db
  • How-to: Dev/deploy — https://opennext.js.org/cloudflare/howtos/dev-deploy
  • How-to: Env vars — https://opennext.js.org/cloudflare/howtos/env-vars
  • How-to: Image — https://opennext.js.org/cloudflare/howtos/image
  • How-to: Custom worker — https://opennext.js.org/cloudflare/howtos/custom-worker
  • How-to: keep_names — https://opennext.js.org/cloudflare/howtos/keep_names
  • How-to: workerd — https://opennext.js.org/cloudflare/howtos/workerd
  • How-to: Skew protection — https://opennext.js.org/cloudflare/howtos/skew
  • How-to: Assets — https://opennext.js.org/cloudflare/howtos/assets
  • How-to: Multi-worker — https://opennext.js.org/cloudflare/howtos/multi-worker
  • Performance — https://opennext.js.org/cloudflare/perf
  • Known issues — https://opennext.js.org/cloudflare/known-issues
  • Troubleshooting — https://opennext.js.org/cloudflare/troubleshooting
  • Migration 0.6 → 1.0.0-beta — https://opennext.js.org/cloudflare/migrate-from-0.6-to-1.0.0-beta
  • Open issues — https://github.com/opennextjs/opennextjs-cloudflare/issues

Version: @opennextjs/cloudflare ^1.18.1 · Next.js 14/15/16 · Wrangler ≥ 3.99.0 · compatibility_date ≥ 2025-05-05 Last Verified: 2026-08-05