chore: import upstream snapshot with attribution

Sources/Containerization/HotplugProvider.swift

@@ -0,0 +1,56 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2026 Apple Inc. and the Containerization 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.
+//===----------------------------------------------------------------------===//
+
+/// A provider that manages hotplug operations for a virtual machine instance.
+///
+/// Conforming types implement the mechanics of hotplugging block devices and
+/// virtiofs shares into a running VM.
+public protocol HotplugProvider: Sendable {
+    /// Hotplug a block device into the running VM.
+    /// - Parameters:
+    ///   - block: The mount configuration for the block device
+    ///   - id: The container ID to associate with this device
+    /// - Returns: The attached filesystem with the device path in the guest
+    func hotplug(_ block: Mount, id: String) async throws -> AttachedFilesystem
+
+    /// Register mounts for a container in the VM's mount registry.
+    /// - Parameters:
+    ///   - id: The container ID
+    ///   - rootfs: The rootfs attachment from hotplug
+    ///   - additionalMounts: Additional mounts to register
+    func registerMounts(id: String, rootfs: AttachedFilesystem, additionalMounts: [Mount]) throws
+
+    /// Release a hotplug device.
+    /// - Parameter id: The container ID who should be released
+    func releaseHotplug(id: String) async throws
+
+    /// Hotplug virtiofs directories into the running VM.
+    /// - Parameters:
+    ///   - mounts: The virtiofs mounts to add
+    ///   - id: The container ID that owns these mounts
+    func hotplugVirtioFS(_ mounts: [Mount], id: String) async throws
+
+    /// Release virtiofs shares for a container.
+    /// - Parameter id: The container ID whose shares should be released
+    func releaseVirtioFS(id: String) async throws
+
+    /// Clean up resources held by the provider.
+    func cleanup()
+}
+
+extension HotplugProvider {
+    public func cleanup() {}
+}