# Apps SDK

How an app is built (manifest, widget, backend, data access, signature) and how it gets into the catalog and onto the display.

> **Type:** area
> **For:** Anyone who wants to understand how the platform’s apps are built, or who prepares an app with platform operations. The SDK is not published today, and the pages describe the contract as it applies in the platform’s source tree.

## Build an app

| Page | When you need it |
|---|---|
| [From template to release](/apps-sdk/template-to-release) | The whole path of a new app: create it from the template with `pnpm app:new`, write the widget, config, texts, and images, check it with `pnpm app:check`, test it, and take it through the pull request into the catalog up to the release in Stable. |
| [An app in the new standard](/apps-sdk/new-app-standard) | Convert an app to templates with size, formats, fit report, surfaces, and the declarative form, using the weather app as an example, plus fit check, store images, old configs, host contract, and the order of the next apps. |

## Basics

| Page | When you need it |
|---|---|
| [What is an app, and how does it get onto a display?](/apps-sdk/about-apps) | From the manifest through release, channels, and installation to the signed bundle on the device: the lifecycle of an app in one picture. |
| [The manifest](/apps-sdk/manifest) | Every field of the app manifest with whether it is required, its format, and its effect, from id and version to legal, unlocks, and connects. |
| [Widget, configuration, and preview](/apps-sdk/widget-and-preview) | defineWidget with configSchema and noResolver, formats (useWidgetFormat), preview variants with size for catalog and thumbnails, and preview states, with the clock example. |
| [Configure widgets](/apps-sdk/configure-widgets) | Read the widget catalog: configSchema as JSON Schema, required fields, examples, and a ready-made widget instance for each built-in building block. |

## Backend and data

| Page | When you need it |
|---|---|
| [Backend: resolvers, fetchers, and jobs](/apps-sdk/backend) | The three decorators @WidgetResolver, @Fetcher, and @JobHandler, their rules, and the capabilities that an app’s backend obtains through tokens. |
| [Data access, permissions, and terms](/apps-sdk/data-access) | dataAccess (reads, external, retention), permissions for team and operator, unlocks and connects, the legal block: what an app discloses before installation. |

## Publish

| Page | When you need it |
|---|---|
| [Signing and the path into the catalog](/apps-sdk/signing-and-catalog) | What belongs to a release, sha256 and Ed25519 signature, the policy on the device, channels canary → beta → stable, and who creates releases today. |
| [The example apps](/apps-sdk/example-apps) | All 26 bundled apps with profile and special feature, and the three references clock (widget only), weather (fetcher), pharmacies-on-duty (resources and job). |