skill: add Android skills

.agents/skills/verified-email/references/android/identity/credential-manager/index.md

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+[Credential Manager](https://developer.android.com/reference/kotlin/androidx/credentials/package-summary) is the recommended Jetpack API for credential exchange
+in Android apps. The Credential Manager API streamlines credential exchange
+across form factors for use cases spanning authentication and authorization. You
+can also use Credential Manager to handle digital credentials and restore user
+credentials on new Android devices.
+
+## Credential Manager features
+
+Credential Manager streamlines the sign-in process and enhances security by
+offering a robust set of capabilities, including:
+
+- **Support for various authentication mechanisms** : Enables users to sign up or sign in to your app using:
+  - [Passkeys](https://developer.android.com/identity/passkeys)
+  - [Sign-in with Google](https://developer.android.com/identity/sign-in/credential-manager-siwg) and other federated sign-in mechanisms
+  - [Passwords](https://developer.android.com/identity/passwords)
+  - [Digital credentials](https://developer.android.com/identity/digital-credentials)
+- **Cross-device credential restore** : Provides integration with [Restore
+  Credentials](https://developer.android.com/identity/sign-in/restore-credentials), allowing users to seamlessly start using your app on a new device.
+- **Seamless integration with credential providers** : Offers support for [credential providers](https://developer.android.com/identity/sign-in/credential-provider), including password managers such as Google Password Manager.
+- **Credential management**: Enables updating the metadata for user credentials, helping to keep credentials consistent across your app and credential providers.
+- **WebView compatibility** : Works with apps that use [WebView](https://developer.android.com/identity/sign-in/credential-manager-webview).
+- **Autofill integration** : Integrates with [autofill](https://developer.android.com/identity/autofill/credential-manager-autofill) to display credentials within the autofill UI.
+
+## Benefits of using Credential Manager
+
+Adopting Credential Manager provides several key advantages for both your
+application and your users:
+
+- **Enhanced security**: Passkeys offer enhanced security and protect users from phishing attempts.
+- **Support for various form factors** : The APIs work across Android [form
+  factors](https://developer.android.com/identity/form-factors), including mobile, Android XR, and Wear OS devices.
+- **Simplified authentication across use cases** : [Digital credentials](https://developer.android.com/identity/digital-credentials), such as digital driver's licenses, corporate IDs, and national ID cards, enable authentication across various use cases, including those requiring [phone number verification](https://developer.android.com/identity/digital-credentials/phone-number-verification).
+- **Improved user experience**: Credential Manager's unified interface gives users a familiar and consistent experience and improves registration and sign-in speeds. The bottom sheet UI appears inline to your app's content, so your users remain within your app's context during sign-in. The following image shows Credential Manager's built-in UI:
+
+![The Credential Manager user interface for passkeys, passwords, and federated sign-ins](https://developer.android.com/static/identity/credential-manager/images/credman-ui.png) **Figure 1.**Credential Manager's built-in unified interface for passkeys, passwords, and federated sign-ins
+
+## Authentication terminology
+
+An entity that requires authentication for its users is known as a **relying
+party**. An authentication workflow typically includes the following components:
+
+- **Relying party client app**: The client---in this case, your Android app---that handles the user interface to create and use passkeys.
+- **Relying party server**: An app server that helps with the creation, storage, and verification of passkeys.
+- **Credential provider** : A component that stores and provides user credentials, such as Google Password Manager. Note that the [FIDO documentation](https://fidoalliance.org/passkeys/) refers to credential providers as credential managers.
+
+## Credential storage
+
+Credential providers, such as Google Password Manager, provide a centralized and
+secure location for users to manage credentials across their devices, further
+simplifying the authentication process. To integrate with Credential Manager as
+a credential provider, see
+[Implement authentication as a credential provider](https://developer.android.com/identity/sign-in/credential-provider).
+
+For more information about how Google Password Manager keeps your credentials
+secure, see
+[Security of Passkeys in the Google Password Manager](https://security.googleblog.com/2022/10/SecurityofPasskeysintheGooglePasswordManager.html).
+
+## Migrate to Credential Manager
+
+Credential Manager is intended to replace legacy Android authentication APIs and
+local FIDO2 credentials. For more information about migrating to Credential
+Manager, see the following guides:
+
+- [Google Sign-In](https://developer.android.com/identity/sign-in/legacy-gsi-migration)
+- [One Tap](https://developer.android.com/identity/legacy/one-tap)
+- [Smart Lock for Passwords](https://developer.android.com/identity/sign-in/smart-lock-migration)
+- [FIDO2](https://developer.android.com/identity/sign-in/fido2-migration)