Using @webiny/sdk to read and write CMS data from external applications. Use this skill when the developer is building a Next.js, Vue, Node.js, or any external app that needs to fetch or write content to Webiny, set up the SDK, use the Result pattern, list/get/create/update/publish entries, filter and sort queries, use TypeScript generics for type safety, work with the File Manager, list languages, trigger or monitor background tasks, or create API keys programmatically. Covers read vs preview mode, the `values` wrapper requirement, correct method names, and the `fields` required parameter, and background task management via `sdk.tasks`. Also covers common SDK errors and troubleshooting — especially "Content model '<modelName>' not found" (which usually means the API key lacks permission, not that the model is missing) and the Website Builder starter pitfall of reusing NEXT_PUBLIC_WEBSITE_BUILDER_API_KEY for Headless CMS reads (that key has no CMS permissions by default and needs either extension or replacement with a CMS-scoped key).