Google is transitioning third-party smart home account linking to be handled
fully and independently within the Google Home app (GHA), retiring legacy
dependencies on the Google Search app and Google Assistant settings.

Core backend OAuth 2.0 infrastructure, credentials, and fulfillment webhooks
remain unchanged. Partners need to update in-app and web deep links, App
Flip allowlists (if supported), and customer-facing setup instructions.

Review your integrations to verify whether the following changes are needed.
If your integration relies on in-app deep links or App Flip, **these updates
must be completed by October 30, 2026 to avoid failures with in-app linking
attempts.**

## Update in-app Link with Google deep links

If your app or product website provides a **Link with Google**
or **Connect to Google Home** button, update the destination URLs to target the
GHA directly.

| Platform and integration type | Legacy destination | New destination (Google Home app) |
|---|---|---|
| Universal Link (Web, iOS, and Android) | `https://madeby.google.com/home-app/?deeplink=setup%2Fha_linking%3Fagent_id%3Dagent-id` | `https://home.google.com/home-app/?deeplink=setup%2Fha_linking%3Fagent_id%3Dagent-id` |
| Custom scheme (Android and iOS) | `assistant-settings://?feature=home_automation&agent_id=agent-id` | `googlehome://setup/ha_linking?agent_id=agent-id` |

> [!NOTE]
> **Note:** If your organization operates multiple Agent IDs across distinct product lines or sub-brands, ensure deep links are updated for all associated Agent IDs.

## Update App Flip allowlists

If your integration supports App Flip and your app or server
enforces allowlist security checks, update your allowlists to include the
GHA.

### For Android app verification

If your Android application validates package
names or signing certificates, add the GHA package name
and SHA-256 release signatures to your allowlist:

- Package name: `com.google.android.apps.chromecast.app`
- Original SHA-256 lineage certificate: `3D:7A:12:23:01:9A:A3:9D:9E:A0:E3:43:6A:B7:C0:89:6B:FB:4F:B6:79:F4:DE:5F:E7:C2:3F:32:6C:8F:99:4A`
- Rotated Play App Signing SHA-256 certificate: `5A:AD:2B:EE:6D:B9:5D:17:E0:5A:08:D7:D1:E6:4C:10:A1:51:18:79:15:44:83:91:6B:6A:E6:C7:FD:9C:B0:C6`
- App Flip requests originate directly from `com.google.android.apps.chromecast.app` rather than `com.google.android.googlequicksearchbox`.

Use `PackageManager.hasSigningCertificate` with
`PackageManager.CERT_INPUT_SHA256` to verify the calling package against both
certificates:

    private const val EXPECTED_PACKAGE = "com.google.android.apps.chromecast.app"
    // Original lineage certificate (3D:7A...) and active rotated
    // Play App Signing certificate (5A:AD...)
    private val EXPECTED_SHA256_CERTS = listOf(
        "3D:7A:12:23:01:9A:A3:9D:9E:A0:E3:43:6A:B7:C0:89:6B:FB:4F:B6:79:F4:DE:5F:E7:C2:3F:32:6C:8F:99:4A",
        "5A:AD:2B:EE:6D:B9:5D:17:E0:5A:08:D7:D1:E6:4C:10:A1:51:18:79:15:44:83:91:6B:6A:E6:C7:FD:9C:B0:C6"
    )

    private fun isTrustedGoogleHomeCaller(pm: PackageManager, callingPackage: String?): Boolean {
        if (callingPackage != EXPECTED_PACKAGE) return false
        return EXPECTED_SHA256_CERTS.any { hex ->
            val bytes = hex.split(":").map { it.toInt(16).toByte() }.toByteArray()
            pm.hasSigningCertificate(callingPackage, bytes, PackageManager.CERT_INPUT_SHA256)
        }
    }

### For iOS server allowlists

Ensure your OAuth authorization server allows the Google Home redirect URI:

- Production: `https://oauth-redirect.googleusercontent.com/a/com.google.Chromecast`

## Update customer support and setup documentation

Review and update user manuals, packaging inserts, support FAQs, and online
knowledge bases:

- Remove instructions asking users to open the Google Search app or Google Assistant settings.
- Adopt standardized Google Home phrasing, such as:
  - "Ensure the Google Home app is installed and follow the account linking process described in [Connect third-party apps to your Google Home
    app](https://support.google.com/googlehome/answer/9159862)."

## References

For additional background and implementation details, see the
[Deep linking](https://developers.home.google.com/cloud-to-cloud/enhancements/deep-linking) guide,
[App Flip for Android](https://developers.home.google.com/cloud-to-cloud/enhancements/app-flip-android) guide, and
[App Flip for iOS](https://developers.home.google.com/cloud-to-cloud/enhancements/app-flip-ios) guide.

For questions about this migration, or if you need help, see the [Cloud-to-cloud
Support page](https://developers.home.google.com/cloud-to-cloud/support) to learn how to contact Google.