Use device specific API for linked devices updating capabilities.

lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/RequestResultExtensions.kt

@@ -2,11 +2,13 @@
  * Copyright 2026 Signal Messenger, LLC
  * SPDX-License-Identifier: AGPL-3.0-only
  */
+@file:JvmName("RequestResultUtil")
 
 package org.whispersystems.signalservice.api
 
 import org.signal.core.util.concurrent.safeBlockingGet
 import org.signal.libsignal.net.RequestResult
+import org.signal.network.exceptions.NonSuccessfulResponseCodeException
 import org.signal.network.exceptions.PushNetworkException
 import org.signal.network.rest.RestStatusCodeError
 import org.signal.network.util.JsonUtil
@@ -49,6 +51,25 @@ fun <T : Any> SignalWebSocket.fromWebSocketRequest(
   }
 }
 
+/**
+ * Unwraps a [RequestResult] to its success value, or throws an [IOException]. Useful for callers bridging the
+ * libsignal [RequestResult] surface back into legacy, exception-based code.
+ *
+ * All non-2xx responses become a [NonSuccessfulResponseCodeException].
+ */
+@Throws(IOException::class)
+fun <T : Any> RequestResult<T, RestStatusCodeError>.successOrThrow(): T {
+  return when (this) {
+    is RequestResult.Success -> result
+    is RequestResult.RetryableNetworkError -> throw networkError
+    is RequestResult.NonSuccess -> throw NonSuccessfulResponseCodeException(error.statusCode, "StatusCode: ${error.statusCode}", error.body, error.headers)
+    is RequestResult.ApplicationError -> throw when (val error = cause) {
+      is IOException, is RuntimeException -> error
+      else -> RuntimeException(error)
+    }
+  }
+}
+
 private fun <T : Any> WebsocketResponse.toRequestResult(clazz: KClass<T>): RequestResult<T, RestStatusCodeError> {
   return if (status < 200 || status > 299) {
     RequestResult.NonSuccess(RestStatusCodeError(status, headers, body?.toByteArray()))

lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/account/AccountApi.kt

@@ -7,9 +7,11 @@ package org.whispersystems.signalservice.api.account
 
 import org.signal.core.util.Base64
 import org.signal.core.util.Base64.encodeUrlSafeWithoutPadding
+import org.signal.libsignal.net.RequestResult
 import org.signal.libsignal.usernames.BaseUsernameException
 import org.signal.libsignal.usernames.Username
 import org.signal.network.NetworkResult
+import org.signal.network.rest.RestStatusCodeError
 import org.signal.network.websocket.WebSocketRequestMessage
 import org.signal.network.websocket.delete
 import org.signal.network.websocket.get
@@ -77,6 +79,17 @@ class AccountApi(private val authWebSocket: SignalWebSocket.AuthenticatedWebSock
     return NetworkResult.fromWebSocketRequest(authWebSocket, request)
   }
 
+  /**
+   * Update the capabilities of the calling device.
+   *
+   * PUT /v1/devices/capabilities
+   * - 200: Success
+   */
+  fun setCapabilities(capabilities: AccountAttributes.Capabilities): RequestResult<Unit, RestStatusCodeError> {
+    val request = WebSocketRequestMessage.put("/v1/devices/capabilities", capabilities)
+    return authWebSocket.fromWebSocketRequest(request, Unit::class)
+  }
+
   /**
    * PUT /v1/accounts/registration_lock
    * - 204: Success