Reviews and authors Cloudflare Workers code against production best practices. Load when writing new Workers, reviewing Worker code, configuring wrangler.jsonc, or checking for common Workers anti-patterns (streaming, floating promises, global state, secrets, bindings, observability). Biases towards retrieval from Cloudflare docs over pre-trained knowledge.
インストールする前に、エージェントに与えられる指示の中身を確認できます。
Your knowledge of Cloudflare Workers APIs, types, and configuration may be outdated. Prefer retrieval over pre-training for any Workers code task — writing or reviewing.
Fetch the latest versions before writing or reviewing Workers code. Do not rely on baked-in knowledge for API signatures, config fields, or binding shapes.
| Source | How to retrieve | Use for |
|---|---|---|
| Workers best practices | Fetch https://developers.cloudflare.com/workers/best-practices/workers-best-practices/ | Canonical rules, patterns, anti-patterns |
| Workers types | See references/review.md for retrieval steps | API signatures, handler types, binding types |
| Wrangler config schema | node_modules/wrangler/config-schema.json | Config fields, binding shapes, allowed values |
| Cloudflare docs | Search tool or https://developers.cloudflare.com/workers/ | API reference, compatibility dates/flags |
Before reviewing or writing Workers code, retrieve the current best practices page and relevant type definitions. If the project's node_modules has an older version, prefer the latest published version.
# Fetch latest workers types
mkdir -p /tmp/workers-types-latest && \
npm pack @cloudflare/workers-types --pack-destination /tmp/workers-types-latest && \
tar -xzf /tmp/workers-types-latest/cloudflare-workers-types-*.tgz -C /tmp/workers-types-latest
# Types at /tmp/workers-types-latest/package/index.d.ts
references/rules.md — all best practice rules with code examples and anti-patternsreferences/review.md — type validation, config validation, binding access patterns, review process| Rule | Summary |
|---|---|
| Compatibility date | Set compatibility_date to today on new projects; update periodically on existing ones |
| nodejs_compat | Enable the nodejs_compat flag — many libraries depend on Node.js built-ins |
| wrangler types | Run wrangler types to generate Env — never hand-write binding interfaces |
| Secrets | Use wrangler secret put, never hardcode secrets in config or source |
| wrangler.jsonc | Use JSONC config for non-secret settings — newer features are JSON-only |
| Rule | Summary |
|---|---|
| Streaming | Stream large/unknown payloads — never await response.text() on unbounded data |
| waitUntil | Use ctx.waitUntil() for post-response work; do not destructure ctx |
| Rule | Summary |
|---|---|
| Bindings over REST | Use in-process bindings (KV, R2, D1, Queues) — not the Cloudflare REST API |
| Queues & Workflows | Move async/background work off the critical path |
| Service bindings | Use service bindings for Worker-to-Worker calls — not public HTTP |
| Hyperdrive | Always use Hyperdrive for external PostgreSQL/MySQL connections |
| Rule | Summary |
|---|---|
| Logs & Traces | Enable observability in config with head_sampling_rate; use structured JSON logging |
| Rule | Summary |
|---|---|
| No global request state | Never store request-scoped data in module-level variables |
| Floating promises | Every Promise must be awaited, returned, voided, or passed to ctx.waitUntil() |
| Rule | Summary |
|---|---|
| Web Crypto | Use crypto.randomUUID() / crypto.getRandomValues() — never Math.random() for security |
| No passThroughOnException | Use explicit try/catch with structured error responses |
| Anti-pattern | Why it matters |
|---|---|
await response.text() on unbounded data | Memory exhaustion — 128 MB limit |
| Hardcoded secrets in source or config | Credential leak via version control |
Math.random() for tokens/IDs | Predictable, not cryptographically secure |
Bare fetch() without await or waitUntil | Floating promise — dropped result, swallowed error |
| Module-level mutable variables for request state | Cross-request data leaks, stale state, I/O errors |
| Cloudflare REST API from inside a Worker | Unnecessary network hop, auth overhead, added latency |
ctx.passThroughOnException() as error handling | Hides bugs, makes debugging impossible |
Hand-written Env interface | Drifts from actual wrangler config bindings |
| Direct string comparison for secret values | Timing side-channel — use crypto.subtle.timingSafeEqual |
Destructuring ctx (const { waitUntil } = ctx) | Loses this binding — throws "Illegal invocation" at runtime |
any on Env or handler params | Defeats type safety for all binding access |
as unknown as T double-cast | Hides real type incompatibilities — fix the design |
implements on platform base classes (instead of extends) | Legacy — loses this.ctx, this.env. Applies to DurableObject, WorkerEntrypoint, Workflow |
env.X inside platform base class | Should be this.env.X in classes extending DurableObject, WorkerEntrypoint, etc. |
any, no unsafe casts (see references/review.md)npx tsc --noEmit, lint for no-floating-promisesreferences/rules.md for each rule's correct patternThis skill covers Workers-specific best practices and code review. For related topics:
durable-objects skillwrangler skillまだレビューはありません。使ってみた感想をお寄せください。
概要と使いどころ
Build AI agents on Cloudflare Workers using the Agents SDK. Load when creating stateful agents, durable workflows, real-time WebSocket apps, scheduled tasks, MCP servers, chat applications, voice agents, or browser automation. Covers Agent class, state management, callable RPC, Workflows, durable execution, queues, retries, observability, and React hooks. Biases towards retrieval from Cloudflare docs over pre-trained knowledge.
日本語の概要は準備中です。原文の説明を表示しています。
When the user wants to optimize content for AI search engines, get cited by LLMs, or appear in AI-generated answers. Also use when the user mentions 'AI SEO,' 'AEO,' 'GEO,' 'LLMO,' 'answer engine optimization,' 'generative engine optimization,' 'LLM optimization,' 'AI Overviews,' 'optimize for ChatGPT,' 'optimize for Perplexity,' 'AI citations,' 'AI visibility,' 'zero-click search,' 'how do I show up in AI answers,' 'LLM mentions,' 'optimize for Claude/Gemini,' 'llms.txt,' 'OKF,' 'Open Knowledge Format,' 'knowledge bundle,' or 'agent-readable site.' Use this whenever someone wants their content to be cited or surfaced by AI assistants and AI search engines. For traditional technical and on-page SEO audits, see seo-audit. For structured data implementation, see schema.
日本語の概要は準備中です。原文の説明を表示しています。
Build an animation from scratch, making the decisions in the order that determines whether it feels right — should it animate at all, what purpose, which tool, which properties, which curve and duration, how it interrupts, how it exits. Writes the implementation. Use when asked to animate something, add motion, make a component feel alive, or build a transition. For critiquing existing motion use review-animations; for auditing a whole codebase use improve-animations.
日本語の概要は準備中です。原文の説明を表示しています。
Reverse-lookup glossary that turns a vague description of a web animation or motion effect into its exact term ("the bouncy thing when a popover opens" → Pop in; "the iOS rubber-band scroll" → Rubber-banding). Use when the user asks "what's it called when…", or describes a motion effect without knowing its name and wants the right word to prompt an AI or designer with. For naming an effect, not designing or building one.
日本語の概要は準備中です。原文の説明を表示しています。
Use when building, running, testing, or bundling JavaScript/TypeScript applications. Reach for Bun when you need to execute scripts, manage dependencies, run tests, or bundle code for production. Bun is a drop-in replacement for Node.js with integrated package manager, test runner, and bundler.
日本語の概要は準備中です。原文の説明を表示しています。
Fallback reference for Cloudflare products that have no dedicated skill here — Pages, storage (KV, D1, R2), AI (Workers AI, Vectorize), feature flags (Flagship), networking (Tunnel, Spectrum), security (WAF, DDoS), and infrastructure-as-code (Terraform, Pulumi). Prefer the focused skill when one fits: agents-sdk for the Agents SDK, durable-objects for Durable Objects, workers-best-practices for reviewing or authoring Worker code, wrangler for CLI commands, sandbox-sdk for sandboxed execution. Biases towards retrieval from Cloudflare docs over pre-trained knowledge.
日本語の概要は準備中です。原文の説明を表示しています。