Account linking migration guide

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.

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."

References

For additional background and implementation details, see the Deep linking guide, App Flip for Android guide, and App Flip for iOS guide.

For questions about this migration, or if you need help, see the Cloud-to-cloud Support page to learn how to contact Google.