Adopt strict concurrency for project (#157)

* Adopt strict concurrency for project

* Fix one warning related to that

* Add version-specific manifest for Swift 6.0

---------

Co-authored-by: Alexey Ivashko <a_ivashko@apple.com>
Co-authored-by: Mattt Zmuda <mattt@me.com>

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:6.0
+// swift-tools-version:6.1
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
@@ -7,14 +7,16 @@ import PackageDescription
 var dependencies: [Package.Dependency] = [
     .package(url: "https://github.com/apple/swift-system.git", from: "1.0.0"),
     .package(url: "https://github.com/apple/swift-log.git", from: "1.5.0"),
-    .package(url: "https://github.com/mattt/eventsource.git", from: "1.1.0")
+    .package(url: "https://github.com/mattt/eventsource.git", from: "1.1.0"),
 ]
 
 // Target dependencies needed on all platforms
 var targetDependencies: [Target.Dependency] = [
     .product(name: "SystemPackage", package: "swift-system"),
     .product(name: "Logging", package: "swift-log"),
-    .product(name: "EventSource", package: "eventsource", condition: .when(platforms: [.macOS, .iOS, .tvOS, .visionOS, .watchOS]))
+    .product(
+        name: "EventSource", package: "eventsource",
+        condition: .when(platforms: [.macOS, .iOS, .tvOS, .visionOS, .watchOS])),
 ]
 
 let package = Package(
@@ -39,7 +41,11 @@ let package = Package(
         // Targets can depend on other targets in this package and products from dependencies.
         .target(
             name: "MCP",
-            dependencies: targetDependencies),
+            dependencies: targetDependencies,
+            swiftSettings: [
+                .enableUpcomingFeature("StrictConcurrency")
+            ]
+        ),
         .testTarget(
             name: "MCPTests",
             dependencies: ["MCP"] + targetDependencies),

Package@swift-6.0.swift

@@ -0,0 +1,49 @@
+// swift-tools-version:6.0
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+// Base dependencies needed on all platforms
+var dependencies: [Package.Dependency] = [
+    .package(url: "https://github.com/apple/swift-system.git", from: "1.0.0"),
+    .package(url: "https://github.com/apple/swift-log.git", from: "1.5.0"),
+    .package(url: "https://github.com/mattt/eventsource.git", from: "1.1.0"),
+]
+
+// Target dependencies needed on all platforms
+var targetDependencies: [Target.Dependency] = [
+    .product(name: "SystemPackage", package: "swift-system"),
+    .product(name: "Logging", package: "swift-log"),
+    .product(
+        name: "EventSource", package: "eventsource",
+        condition: .when(platforms: [.macOS, .iOS, .tvOS, .visionOS, .watchOS])),
+]
+
+let package = Package(
+    name: "mcp-swift-sdk",
+    platforms: [
+        .macOS("13.0"),
+        .macCatalyst("16.0"),
+        .iOS("16.0"),
+        .watchOS("9.0"),
+        .tvOS("16.0"),
+        .visionOS("1.0"),
+    ],
+    products: [
+        // Products define the executables and libraries a package produces, making them visible to other packages.
+        .library(
+            name: "MCP",
+            targets: ["MCP"])
+    ],
+    dependencies: dependencies,
+    targets: [
+        // Targets are the basic building blocks of a package, defining a module or a test suite.
+        // Targets can depend on other targets in this package and products from dependencies.
+        .target(
+            name: "MCP",
+            dependencies: targetDependencies),
+        .testTarget(
+            name: "MCPTests",
+            dependencies: ["MCP"] + targetDependencies),
+    ]
+)

Sources/MCP/Base/Messages.swift

@@ -20,7 +20,7 @@ extension Value: NotRequired {
 // MARK: -
 
 /// A method that can be used to send requests and receive responses.
-public protocol Method {
+public protocol Method: Sendable {
     /// The parameters of the method.
     associatedtype Parameters: Codable, Hashable, Sendable = Empty
     /// The result of the method.