Replace single-package scaffolding with monorepo Package.swift generation

Sources/SwiftGtkGenCore/CodeGen+Scaffolding.swift

@@ -20,6 +20,7 @@ extension CodeGenerator {
     ///   - repository: The parsed GIR repository containing namespace metadata,
     ///     `<c:include>`, `<include>`, and `<package>` values.
     /// - Returns: A dictionary of relative path → file content.
+    @available(*, deprecated, message: "Use generateMonorepoScaffolding(analysis:) for monorepo packages.")
     public static func generatePackageScaffolding(config: GenerationConfig, repository: Repository) -> [String: String] {
         var files: [String: String] = [:]
         let cName = "C\(config.library)"
@@ -114,6 +115,122 @@ extension CodeGenerator {
         return files
     }
 
+    // MARK: - Monorepo Package Scaffolding Generation
+
+    /// Generates all scaffolding files for the monorepo: Package.swift,
+    /// C bridge module maps and umbrella headers, and re-export files.
+    ///
+    /// - Parameter analysis: The resolved multi-package analysis.
+    /// - Returns: A dictionary of relative path → file content.
+    public static func generateMonorepoScaffolding(analysis: MultiPackageAnalysis) -> [String: String] {
+        var files: [String: String] = [:]
+
+        // Re-export umbrella files
+        let umbrellas = generateReexportUmbrellas(analysis: analysis)
+        for (path, content) in umbrellas {
+            files[path] = content
+        }
+
+        // C bridge files
+        for (moduleName, repo) in analysis.repositories {
+            let cName = "C\(moduleName)"
+            let ns = repo.namespaces.first { $0.name == moduleName } ?? repo.namespaces.first
+
+            let sharedLibrary = ns?.cSharedLibrary ?? ""
+            let libraries = sharedLibrary.split(separator: ",").map(String.init)
+            let allLinkNames = libraries.compactMap { extractLinkName(from: $0) }
+            let lowerModName = moduleName.lowercased()
+            let cHeader = repo.cHeaderPath
+            let umbrellaHeader = cHeader.isEmpty
+                ? "#include <\(lowerModName)/\(lowerModName).h>"
+                : "#include <\(cHeader)>"
+
+            // External C link names from GIR includes
+            var externalLinks: [String] = []
+            for include in repo.includedPackages {
+                let el = include.name.lowercased()
+                if !externalLinks.contains(el) {
+                    externalLinks.append(el)
+                }
+            }
+
+            let linkLines = (allLinkNames + externalLinks).map { "    link \"\($0)\"" }.joined(separator: "\n")
+            let moduleMap = """
+            module \(cName) [system] {
+                header "\(cName).h"
+            \(linkLines)
+            }
+            """
+            files["Sources/\(cName)/module.modulemap"] = moduleMap
+            files["Sources/\(cName)/\(cName).h"] = umbrellaHeader + "\n"
+        }
+
+        // Monorepo Package.swift
+        let packageSwift = generateMonorepoPackage(analysis: analysis)
+        files["Package.swift"] = packageSwift
+
+        return files
+    }
+
+    /// Generates the single monorepo Package.swift containing all targets.
+    private static func generateMonorepoPackage(analysis: MultiPackageAnalysis) -> String {
+        let moduleNames = analysis.repositories.keys.sorted()
+
+        // Products
+        var products = ""
+        for name in moduleNames {
+            products += "        .library(name: \"\(name)\", targets: [\"\(name)\"]),\n"
+        }
+
+        // C system library targets
+        var cTargets = ""
+        for name in moduleNames {
+            let cName = "C\(name)"
+            cTargets += "        .systemLibrary(name: \"\(cName)\", path: \"Sources/\(cName)\"),\n"
+        }
+
+        // Swift wrapper targets
+        var swiftTargets = ""
+        for name in moduleNames {
+            let cName = "C\(name)"
+            let dirDeps = analysis.directDependencies[name] ?? []
+            var depList = "\"\(cName)\""
+            for dep in dirDeps.sorted() {
+                depList += ", \"\(dep)\""
+            }
+            swiftTargets += """
+                    .target(
+                        name: "\(name)",
+                        dependencies: [\(depList)],
+                        swiftSettings: swiftSettings
+                    ),
+
+            """
+        }
+
+        return """
+        // swift-tools-version: 6.2
+        import PackageDescription
+
+        let swiftSettings: [SwiftSetting] = [
+            .enableExperimentalFeature("StrictConcurrency=complete"),
+            .defaultIsolation(MainActor.self),
+            .enableUpcomingFeature("NonisolatedNonsendingByDefault"),
+        ]
+
+        let package = Package(
+            name: "gtk-swift",
+            platforms: [.macOS(.v14)],
+            products: [
+        \(products)    ],
+            targets: [
+        \(cTargets)
+        \(swiftTargets)    ]
+        )
+
+        """
+    }
+
     /// Extracts link name from a shared-library string like "libgtk-4.so.1" -> "gtk-4".
     private static func extractLinkName(from sharedLib: String) -> String? {
         guard sharedLib.hasPrefix("lib") else { return nil }