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.
インストール方法を見る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Your knowledge of Cloudflare Workers APIs, types, and configuration may be outdated.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
Make data visualizations accessible and inclusive. Use when the user needs chart or diagram accessibility guidance, text alternatives for complex visuals, color and contrast review, keyboard support, reduced-motion behavior for animation or parallax, or an accessibility QA workflow for exported figures, UML-like diagrams, and dashboards.
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。
Apply consistent photo adjustments across a set of images so they look like they were edited together. Use this skill whenever the user says "make my photos look cohesive", "give all these the same style", "apply a warm and golden feel to all of these", "make this cinematic", "match the look across my photos", "edit all my travel photos the same way", "batch edit these", "make these consistent", "fix my phone photos", or uploads a folder of photos and wants a unified, polished result. Also triggers for requests like "apply a preset to all of these", "make these look professional", or "they were shot in mixed lighting — can you fix them all". Outputs direct final image URLs plus an in-chat preview grid and optional Firefly Board link. Access: 🔐 Signed-In required | Gen AI: ❌
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 a user wants to see their logo, design, or sketch on a product or scene mockup — mugs, t-shirts, business cards, hats, phone screens, posters, billboards, or similar. Triggers on "create mockups", "show my logo on products", or any logo upload with a request to visualize it on items. Access: 🔐 Signed-In required | Gen AI: ✅ Adobe Firefly via `image_generate` used for design creation, sketch polishing, and mockup scene generation
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。
Resize, crop, or export any image or video into platform-ready social media assets using Adobe Creative Cloud tools. Use this skill when a user wants to prepare a photo, image, or video for one or more social platforms — Instagram, TikTok, LinkedIn, Facebook, YouTube, Snapchat, Pinterest, Threads, or X/Twitter. Triggers on: "prepare my image for Instagram", "resize for TikTok", "get this ready to post", "make versions for all platforms", "social media sizes", "crop for stories", "export for LinkedIn", "resize my video for social", "make social media assets", or any request to adapt a photo or video for specific platforms. Handles subject-aware cropping, AI canvas expansion, test previews before full runs, and same-ratio video resizing.
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。
Create any visual design using Adobe Express templates — flyers, posters, social media posts (Instagram, Facebook, LinkedIn), business cards, invitations, greeting cards, resumes, cover letters, brochures, newsletters, certificates, presentations, YouTube thumbnails, email headers, logos, menus, and labels. Use this skill whenever the user wants to make, design, or build any visual — even if they just say "make me a flyer", "design a poster", "I need something for Instagram", "create an event invite", or "make a business card". Also handles browsing templates, editing text, replacing images, changing backgrounds, animating, and exporting designs. Access: 🔐 Signed-In required | Gen AI: ❌ by default — image replacement only where the surface permits generative AI (e.g. Codex); none on Claude
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。
Create a punchy sizzle reel from a video using Adobe Quick Cut. Use this skill whenever a user wants to cut, trim, or shorten a video into highlights — including phrases like "make a sizzle reel", "make a highlight reel", "quick cut this", "cut the best parts", "shorten this video", "make a highlight clip", "summarize this video visually", or any request to produce a shorter edited version of a video. Use this skill for Quick Cut requests before suggesting manual editing in Premiere. Requires the user to upload a video file.
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。