[registry]: add RegistryKeychainClient to the main client library

Sources/ContainerCommands/Registry/RegistryList.swift

@@ -39,10 +39,8 @@ extension Application {
             aliases: ["ls"])
 
         public func run() async throws {
-            let keychain = KeychainHelper(securityDomain: Constants.keychainID)
-            let registryInfos = try keychain.list()
-            let registries = registryInfos.map { RegistryResource(from: $0) }
-
+            let client = RegistryKeychainClient()
+            let registries = try await client.list()
             try printRegistries(registries: registries, format: format)
         }
 

Sources/ContainerCommands/Registry/RegistryLogin.swift

@@ -16,6 +16,7 @@
 
 import ArgumentParser
 import ContainerAPIClient
+import ContainerResource
 import Containerization
 import ContainerizationError
 import ContainerizationOCI
@@ -45,6 +46,7 @@ extension Application {
         var server: String
 
         public func run() async throws {
+            let keychainClient = RegistryKeychainClient()
             var username = self.username
             var password = ""
             if passwordStdin {
@@ -57,12 +59,11 @@ extension Application {
                 }
                 password = String(decoding: passwordData, as: UTF8.self).trimmingCharacters(in: .whitespacesAndNewlines)
             }
-            let keychain = KeychainHelper(securityDomain: Constants.keychainID)
             if username == "" {
-                username = try keychain.userPrompt(hostname: server)
+                username = try await keychainClient.userPrompt(hostname: server)
             }
             if password == "" {
-                password = try keychain.passwordPrompt()
+                password = try await keychainClient.passwordPrompt()
                 print()
             }
 
@@ -90,7 +91,7 @@ extension Application {
                 )
             )
             try await client.ping()
-            try keychain.save(hostname: server, username: username, password: password)
+            try await keychainClient.login(hostname: server, username: username, password: password)
             print("Login succeeded")
         }
     }

Sources/ContainerCommands/Registry/RegistryLogout.swift

@@ -34,9 +34,9 @@ extension Application {
         var registry: String
 
         public func run() async throws {
-            let keychain = KeychainHelper(securityDomain: Constants.keychainID)
-            let r = Reference.resolveDomain(domain: registry)
-            try keychain.delete(hostname: r)
+            let hostname = Reference.resolveDomain(domain: registry)
+            let client = RegistryKeychainClient()
+            try await client.logout(hostname: hostname)
         }
     }
 }

Sources/Services/ContainerAPIService/Client/RegistryKeychainClient.swift

@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2026 Apple Inc. and the container project authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+import ContainerResource
+import ContainerXPC
+import ContainerizationOCI
+import ContainerizationOS
+import Foundation
+
+/// A  client for managing registry credentials.
+public struct RegistryKeychainClient {
+    private let keychain: KeychainHelper
+
+    /// Creates a a new instance using the default registry keychain domain.
+    public init() {
+        self.keychain = KeychainHelper(securityDomain: Constants.keychainID)
+    }
+
+    /// Returns all registry credentials stored in the keychain.
+    /// - Returns: An array of `RegistryResource` values representing saved registry entries.
+    /// - Throws: An error if the keychain query fails.
+    public func list() async throws -> [RegistryResource] {
+        let registries = try keychain.list()
+        return registries.map { RegistryResource(from: $0) }
+    }
+
+    /// Stores credentials for a registry in the keychain.
+    /// - Parameters:
+    ///   - hostname: The registry hostname.
+    ///   - username: The username for authentication.
+    ///   - password: The password for authentication.
+    /// - Throws: An error if the credentials cannot be saved to the keychain.
+    public func login(hostname: String, username: String, password: String) async throws {
+        try keychain.save(hostname: hostname, username: username, password: password)
+    }
+
+    /// Removes stored credentials for a registry from the keychain.
+    /// - Parameter hostname: The registry hostname.
+    /// - Throws: An error if the credentials cannot be removed.
+    public func logout(hostname: String) async throws {
+        try keychain.delete(hostname: hostname)
+    }
+
+    /// Prompts the user to enter a registry username.
+    /// - Parameter hostname: The registry hostname being authenticated.
+    /// - Returns: The username entered by the user.
+    /// - Throws: An error if input cannot be read.
+    public func userPrompt(hostname: String) async throws -> String {
+        try keychain.userPrompt(hostname: hostname)
+    }
+
+    /// Prompts the user to enter a registry password.
+    /// - Returns: The password entered by the user.
+    /// - Throws: An error if input cannot be read.
+    public func passwordPrompt() async throws -> String {
+        try keychain.passwordPrompt()
+    }
+}