chore: import upstream snapshot with attribution

Sources/Containerization/Image/Unpacker/Unpacker.swift

@@ -0,0 +1,40 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025-2026 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.
+//===----------------------------------------------------------------------===//
+
+import ContainerizationExtras
+import ContainerizationOCI
+import Foundation
+
+/// The `Unpacker` protocol defines a standardized interface that involves
+/// decompressing, extracting image layers and preparing it for use.
+///
+/// The `Unpacker` is responsible for managing the lifecycle of the
+/// unpacking process, including any temporary files or resources, until the
+/// `Mount` object is produced.
+public protocol Unpacker {
+
+    /// Unpacks the provided image to a specified path for a given platform.
+    ///
+    /// This asynchronous method should handle the entire unpacking process, from reading
+    /// the `Image` layers for the given `Platform` via its `Manifest`,
+    /// to making the extracted contents available as a `Mount`.
+    /// Implementations of this method may apply platform-specific optimizations
+    /// or transformations during the unpacking.
+    ///
+    /// Progress updates can be observed via the optional `progress` handler.
+    func unpack(_ image: Image, for platform: Platform, at path: URL, progress: ProgressHandler?) async throws -> Mount
+
+}