Swift UI Missing argument for parameter in @main app call in List View

Welcome to the forum.

The error message is very explicit. You have to pass a Project instance as a parameter, not the structure type itself.

@main struct MyApp: App {
    var body: some Scene {
        WindowGroup { ContentView(project: Project(name: "dummy", icon: "", isFavorite: true, color: .red, compoundscore: 0)) } // vs project: Project
    }
}

Another way is to initialise var project with a dummy instance. No more need to pass parameter in call.

Note: when you post code, please use code formatter to make it readable.

@main struct MyApp: App {
    var body: some Scene {
        WindowGroup { ContentView() } // no more need for parameter is var is initialised in ContentView
    }
}

struct Project: Identifiable {
    var name: String
    var icon: String
    var isFavorite: Bool
    var color: Color
    let id = UUID()
    var compoundscore : Float
    static func CurrentProjects() -> [Project] {    // name should start with lowercase
        return [Project(name: "Test Project", icon: "🍎", isFavorite: true, color: .red, compoundscore: 4.5),
                Project(name: "Swimming", icon: "🏊", isFavorite: false, color: .orange, compoundscore: 12.5),
                Project(name: "Archery", icon: "🏹", isFavorite: false, color: .yellow, compoundscore: 37.5) ]
    }
}

struct ProjectRow: View {
    let project: Project 
    
    var body: some View {
        HStack {
            Text(project.icon)
                .font(.title)
            Text(project.name)
            Spacer()
            Image(systemName: project.isFavorite ? "heart.fill" : "heart")
        }
    }
}

struct ContentView: View {
    var CurrentProjectlist: [Project] = Project.CurrentProjects()
    
    var project: Project = Project(name: "dummy", icon: "", isFavorite: true, color: .red, compoundscore: 0). // Initial value to avoid having to pass parameter on call
    
    var body: some View {
        NavigationView {
            List {
                Section {
                    if #available(iOS 17.0, *) {
                        ForEach(CurrentProjectlist) { project in
                            ProjectRow(project: project)
                        }
                        .listRowBackground(
                            Capsule()
                                .fill(Color(project.color))
                                .padding(.vertical, 2).padding(.horizontal, 20)
                        )
                        .listRowSeparator(.hidden)
                        .foregroundColor(.indigo)
                    } else {
                        // Fallback on earlier versions
                    }
                    
                } header: {
                    Text("CI Projects")
                }
                .listRowBackground(Color.blue)
                .foregroundColor(.black)
                
                
                .listRowInsets(.init(top: 0, leading: 40, bottom: 0, trailing: 40))
                
                
                .listRowBackground(Color.black)
                .listSectionSeparatorTint(.yellow)
                .headerProminence(.increased)
                .listRowInsets(EdgeInsets.init(top: 0, leading: 50, bottom: 0, trailing: 50))
            }
            .scrollContentBackground(.hidden)
            .background(
                Image("cool background")
                    .resizable()
                    .scaledToFill()
                    .clipped()
                    .edgesIgnoringSafeArea(.all)
                    .blur(radius: 3)
                    .overlay(Color.red.opacity(0.2))
            )
            .environment(\.defaultMinListHeaderHeight, 20)
            .environment(\.defaultMinListRowHeight, 70)
            .navigationTitle("Navigator")
        }
        
    }
}

I tested and it works OK: