Fix quick startup guide

Examples/HelloWorldNoTraits/README.md

@@ -26,7 +26,7 @@ This example disables all the traits. To disable one or several traits, modify `
 
 ```swift
 	dependencies: [
-			.package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "2.0.0-beta", traits: [])
+			.package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "3.0.0", traits: [])
 	],
 ```
 

Sources/AWSLambdaPluginHelper/lambda-init/Initializer.swift

@@ -18,6 +18,9 @@ import FoundationEssentials
 import Foundation
 #endif
 
+/// The `SupportedPlatform.MacOSVersion` matching the `LambdaSwift 2.0` availability macro.
+private let minimumMacOSVersion = "v15"
+
 @available(LambdaSwift 2.0, *)
 struct Initializer {
 
@@ -59,6 +62,14 @@ struct Initializer {
                 with: ""
             )
             print("✅ Lambda function written to \(relativePath)")
+
+            // The runtime API is only available on macOS 15 or later. Without the matching
+            // platform requirement, the generated function does not compile on macOS.
+            try self.addMacOSPlatformRequirement(
+                to: configuration.destinationDir,
+                verboseLogging: configuration.verboseLogging
+            )
+
             print("📦 You can now package with: 'swift package lambda-build'")
         } catch {
             print("🛑 Failed to create the Lambda function file: \(error)")
@@ -68,6 +79,51 @@ struct Initializer {
         }
     }
 
+    /// Adds the macOS platform requirement of `AWSLambdaRuntime` to the package manifest.
+    ///
+    /// The runtime API is annotated with `@available(LambdaSwift 2.0, *)`, an availability macro
+    /// that expands to `macOS 15.0`. A package that does not declare that platform requirement
+    /// fails to build on macOS with "is only available in macOS 15.0 or newer".
+    ///
+    /// `platforms` is set by appending an assignment at the end of the manifest rather than by
+    /// inserting an argument into the `Package(...)` call. `Package` is a class, so mutating it
+    /// after initialization is valid, and appending needs no parsing of the existing manifest.
+    private func addMacOSPlatformRequirement(to destinationDir: URL, verboseLogging: Bool) throws {
+        let manifestURL = destinationDir.appendingPathComponent("Package.swift")
+
+        guard FileManager.default.fileExists(atPath: manifestURL.path) else {
+            print("⚠️  No Package.swift found at \(manifestURL.path).")
+            print("   Add 'platforms: [.macOS(.\(minimumMacOSVersion))]' to your package manifest manually.")
+            return
+        }
+
+        let manifest = try String(contentsOf: manifestURL, encoding: .utf8)
+
+        // Don't override platform requirements the developer already declared.
+        let declaresPlatforms = manifest.split(separator: "\n").contains { line in
+            let statement = line.trimming(while: \.isWhitespace)
+            return statement.hasPrefix("platforms:") || statement.hasPrefix("package.platforms")
+        }
+        guard !declaresPlatforms else {
+            if verboseLogging {
+                print("Package.swift already declares platform requirements, leaving it unchanged")
+            }
+            return
+        }
+
+        let existing = manifest.hasSuffix("\n") ? manifest : manifest + "\n"
+        try """
+        \(existing)
+        // The AWSLambdaRuntime API requires macOS 15 or later.
+        package.platforms = [
+            .macOS(.\(minimumMacOSVersion))
+        ]
+
+        """.write(to: manifestURL, atomically: true, encoding: .utf8)
+
+        print("✅ Added 'package.platforms = [.macOS(.\(minimumMacOSVersion))]' to Package.swift")
+    }
+
     /// Finds the main entry point Swift file in the Sources directory.
     ///
     /// Strategy:

Sources/AWSLambdaRuntime/Docs.docc/Resources/code/03-02-03-package.swift

@@ -9,6 +9,6 @@ let package = Package(
         .macOS(.v15)
     ],
     dependencies: [
-        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "2.0.0")
+        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "3.0.0")
     ]
 )

Sources/AWSLambdaRuntime/Docs.docc/Resources/code/03-02-04-package.swift

@@ -12,6 +12,6 @@ let package = Package(
         .executable(name: "PalindromeLambda", targets: ["PalindromeLambda"])
     ],
     dependencies: [
-        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "2.0.0")
+        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "3.0.0")
     ]
 )

Sources/AWSLambdaRuntime/Docs.docc/Resources/code/03-02-05-package.swift

@@ -12,7 +12,7 @@ let package = Package(
         .executable(name: "PalindromeLambda", targets: ["PalindromeLambda"])
     ],
     dependencies: [
-        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "2.0.0")
+        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "3.0.0")
     ],
     targets: [
         .executableTarget(

Sources/AWSLambdaRuntime/Docs.docc/lambda-handlers.md

@@ -67,7 +67,7 @@ let package = Package(
     name: "MyLambda",
     platforms: [.macOS(.v15)],
     dependencies: [
-        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "2.0.0"),
+        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "3.0.0"),
         .package(url: "https://github.com/awslabs/swift-aws-lambda-events.git", from: "1.0.0"),
     ],
     targets: [

Sources/AWSLambdaRuntime/Docs.docc/managed-instances.md

@@ -91,7 +91,7 @@ The managed instances support is implemented behind a Swift package trait (`Mana
 dependencies: [
     .package(
         url: "https://github.com/awslabs/swift-aws-lambda-runtime.git",
-        from: "2.0.0",
+        from: "3.0.0",
         traits: [
             // Keep other default traits but exclude ManagedRuntimeSupport
             "FoundationJSONSupport",

Sources/AWSLambdaRuntime/Docs.docc/quick-setup.md

@@ -44,7 +44,7 @@ let package = Package(
         .executable(name: "MyFirstLambdaFunction", targets: ["MyFirstLambdaFunction"]),
     ],
     dependencies: [
-        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "2.0.0"),
+        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "3.0.0"),
     ],
     targets: [
         .executableTarget(