honeyDueKMP/iosApp/REFACTORING_PLAN.md

# iOS Codebase Refactoring Plan

## Overview

Refactor the MyCrib iOS codebase to improve adherence to SOLID principles and DRY patterns. This plan targets ~1,500 lines of code reduction while significantly improving testability and maintainability.

**Scope**: `MyCribKMM/iosApp/iosApp/`
**Estimated Effort**: 4-5 focused sessions
**Risk Level**: Medium (ViewModels are central to app functionality)

### User Preferences
- **DI Approach**: Factory pattern (`Dependencies.current.make*()`)
- **View Refactoring**: Yes, include Views alongside ViewModels
- **File Organization**: New `Core/` folder for foundational abstractions

---

## Completion Status

| Session | Status | Notes |
|---------|--------|-------|
| Session 1: Core Abstractions | ✅ Complete | StateFlowObserver, ValidationRules created; BaseViewModel skipped per user preference |
| Session 2: Type Conversions | ✅ Complete | KotlinTypeExtensions.swift created with .asKotlin helpers |
| Session 3: State Management | ✅ Complete | ActionState.swift created for TaskViewModel |
| Session 4: Dependency Injection | ✅ Complete | Dependencies.swift + TokenStorageProtocol (simplified due to Kotlin API constraints) |
| Session 5: View Layer | ✅ Complete | ViewState, LoadingOverlay, AsyncContentView, Form State containers created |

### Implementation Notes

1. **BaseViewModel Skipped**: Per user preference, ViewModels continue to extend `ObservableObject` directly
2. **Protocol Simplification**: Full ViewModel protocols removed due to Kotlin-generated API parameter label mismatches; only `TokenStorageProtocol` retained
3. **Form State Containers**: Created as standalone structs that can be adopted incrementally by views
4. **All ViewModels Updated**: 9 ViewModels now use StateFlowObserver pattern and support optional DI

### Files Created

```
iosApp/Core/
├── StateFlowObserver.swift       ✅
├── ValidationRules.swift         ✅
├── ActionState.swift             ✅
├── ViewState.swift               ✅
├── LoadingOverlay.swift          ✅
├── AsyncContentView.swift        ✅
├── Dependencies.swift            ✅
├── Protocols/
│   └── ViewModelProtocols.swift  ✅ (TokenStorageProtocol only)
├── FormStates/
│   ├── TaskFormStates.swift      ✅
│   ├── ResidenceFormState.swift  ✅
│   ├── ContractorFormState.swift ✅
│   └── DocumentFormState.swift   ✅
└── Extensions/
    └── KotlinTypeExtensions.swift ✅
```

### ViewModels Updated

- [x] ResidenceViewModel - StateFlowObserver + DI
- [x] TaskViewModel - StateFlowObserver + ActionState + DI
- [x] ContractorViewModel - StateFlowObserver + DI
- [x] DocumentViewModel - StateFlowObserver + DI
- [x] LoginViewModel - StateFlowObserver + DI
- [x] ProfileViewModel - StateFlowObserver + DI
- [x] RegisterViewModel - StateFlowObserver + ValidationRules + DI
- [x] VerifyEmailViewModel - StateFlowObserver + DI
- [x] PasswordResetViewModel - StateFlowObserver + ValidationRules + DI

### Views Updated with ListAsyncContentView

- [x] ResidencesListView - Now uses `ListAsyncContentView` with extracted `ResidencesContent`
- [x] ContractorsListView - Now uses `ListAsyncContentView` with extracted `ContractorsContent`
- [x] WarrantiesTabContent - Now uses `ListAsyncContentView` with extracted `WarrantiesListContent`
- [x] DocumentsTabContent - Now uses `ListAsyncContentView` with extracted `DocumentsListContent`

---

## Phase 1: Core Abstractions

### 1.1 Create StateFlow Observation Utility

**Problem**: 26 instances of identical StateFlow observation boilerplate across all ViewModels (~800 lines)

**Solution**: Create a reusable utility that handles Kotlin StateFlow observation with proper MainActor handling.

**New File**: `iosApp/Core/StateFlowObserver.swift`

```swift
import Foundation
import ComposeApp

@MainActor
class StateFlowObserver {

    /// Observe a Kotlin StateFlow and handle loading/success/error states
    static func observe<T>(
        _ stateFlow: Kotlinx_coroutines_coreStateFlow,
        onLoading: (() -> Void)? = nil,
        onSuccess: @escaping (T) -> Void,
        onError: ((String) -> Void)? = nil,
        resetState: (() -> Void)? = nil
    ) {
        Task {
            for await state in stateFlow {
                if state is ApiResultLoading {
                    await MainActor.run {
                        onLoading?()
                    }
                } else if let success = state as? ApiResultSuccess<T> {
                    await MainActor.run {
                        onSuccess(success.data!)
                    }
                    resetState?()
                    break
                } else if let error = state as? ApiResultError {
                    await MainActor.run {
                        let message = ErrorMessageParser.parse(error.message ?? "Unknown error")
                        onError?(message)
                    }
                    resetState?()
                    break
                } else if state is ApiResultIdle {
                    // Idle state, continue observing
                    continue
                }
            }
        }
    }

    /// Observe with automatic isLoading/errorMessage binding
    static func observeWithState<T>(
        _ stateFlow: Kotlinx_coroutines_coreStateFlow,
        isLoading: Binding<Bool>,
        errorMessage: Binding<String?>,
        onSuccess: @escaping (T) -> Void,
        resetState: (() -> Void)? = nil
    ) {
        observe(
            stateFlow,
            onLoading: { isLoading.wrappedValue = true },
            onSuccess: { data in
                isLoading.wrappedValue = false
                onSuccess(data)
            },
            onError: { error in
                isLoading.wrappedValue = false
                errorMessage.wrappedValue = error
            },
            resetState: resetState
        )
    }
}
```

**Files to Update** (remove duplicated observation code):
- `Residence/ResidenceViewModel.swift`
- `Task/TaskViewModel.swift`
- `Contractor/ContractorViewModel.swift`
- `Documents/DocumentViewModel.swift`
- `Login/LoginViewModel.swift`
- `Profile/ProfileViewModel.swift`
- `Register/RegisterView.swift`
- `VerifyEmail/VerifyEmailViewModel.swift`
- `PasswordReset/PasswordResetViewModel.swift`

---

### 1.2 Create Base ViewModel Class

**Problem**: Every ViewModel repeats `isLoading`, `errorMessage`, and basic state handling patterns.

**Solution**: Abstract common ViewModel functionality into a base class.

**New File**: `iosApp/Core/BaseViewModel.swift`

```swift
import Foundation
import SwiftUI
import ComposeApp

@MainActor
class BaseViewModel: ObservableObject {
    @Published var isLoading: Bool = false
    @Published var errorMessage: String?

    /// Clear error message
    func clearError() {
        errorMessage = nil
    }

    /// Set loading state
    func setLoading(_ loading: Bool) {
        isLoading = loading
    }

    /// Handle error with optional parsing
    func handleError(_ message: String?) {
        errorMessage = ErrorMessageParser.parse(message ?? "An unexpected error occurred")
        isLoading = false
    }

    /// Observe StateFlow with automatic state binding
    func observe<T>(
        _ stateFlow: Kotlinx_coroutines_coreStateFlow,
        onSuccess: @escaping (T) -> Void,
        resetState: (() -> Void)? = nil
    ) {
        StateFlowObserver.observe(
            stateFlow,
            onLoading: { [weak self] in self?.isLoading = true },
            onSuccess: { [weak self] (data: T) in
                self?.isLoading = false
                onSuccess(data)
            },
            onError: { [weak self] error in
                self?.handleError(error)
            },
            resetState: resetState
        )
    }
}
```

**ViewModels to Refactor** (inherit from BaseViewModel):
- All 10 ViewModels will extend `BaseViewModel` instead of `ObservableObject`

---

### 1.3 Create Validation Rules Module

**Problem**: Email, password, and field validation logic duplicated across 4+ ViewModels.

**Solution**: Centralize all validation rules in a single module.

**New File**: `iosApp/Core/ValidationRules.swift`

```swift
import Foundation

enum ValidationError: LocalizedError {
    case required(field: String)
    case invalidEmail
    case passwordTooShort(minLength: Int)
    case passwordMismatch
    case invalidCode(expectedLength: Int)
    case invalidUsername
    case custom(message: String)

    var errorDescription: String? {
        switch self {
        case .required(let field):
            return "\(field) is required"
        case .invalidEmail:
            return "Please enter a valid email address"
        case .passwordTooShort(let minLength):
            return "Password must be at least \(minLength) characters"
        case .passwordMismatch:
            return "Passwords do not match"
        case .invalidCode(let length):
            return "Code must be \(length) digits"
        case .invalidUsername:
            return "Username can only contain letters, numbers, and underscores"
        case .custom(let message):
            return message
        }
    }
}

struct ValidationRules {

    // MARK: - Email Validation

    static func validateEmail(_ email: String) -> ValidationError? {
        let trimmed = email.trimmingCharacters(in: .whitespacesAndNewlines)

        if trimmed.isEmpty {
            return .required(field: "Email")
        }

        let emailRegex = "^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}$"
        let predicate = NSPredicate(format: "SELF MATCHES %@", emailRegex)

        if !predicate.evaluate(with: trimmed) {
            return .invalidEmail
        }

        return nil
    }

    // MARK: - Password Validation

    static func validatePassword(_ password: String, minLength: Int = 8) -> ValidationError? {
        if password.isEmpty {
            return .required(field: "Password")
        }

        if password.count < minLength {
            return .passwordTooShort(minLength: minLength)
        }

        return nil
    }

    static func validatePasswordMatch(_ password: String, _ confirmPassword: String) -> ValidationError? {
        if password != confirmPassword {
            return .passwordMismatch
        }
        return nil
    }

    // MARK: - Code Validation

    static func validateCode(_ code: String, expectedLength: Int = 6) -> ValidationError? {
        let trimmed = code.trimmingCharacters(in: .whitespacesAndNewlines)

        if trimmed.isEmpty {
            return .required(field: "Code")
        }

        if trimmed.count != expectedLength || !trimmed.allSatisfy({ $0.isNumber }) {
            return .invalidCode(expectedLength: expectedLength)
        }

        return nil
    }

    // MARK: - Username Validation

    static func validateUsername(_ username: String) -> ValidationError? {
        let trimmed = username.trimmingCharacters(in: .whitespacesAndNewlines)

        if trimmed.isEmpty {
            return .required(field: "Username")
        }

        let usernameRegex = "^[A-Za-z0-9_]+$"
        let predicate = NSPredicate(format: "SELF MATCHES %@", usernameRegex)

        if !predicate.evaluate(with: trimmed) {
            return .invalidUsername
        }

        return nil
    }

    // MARK: - Required Field

    static func validateRequired(_ value: String, fieldName: String) -> ValidationError? {
        if value.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
            return .required(field: fieldName)
        }
        return nil
    }
}
```

**Files to Update** (remove inline validation):
- `Login/LoginViewModel.swift`
- `Register/RegisterView.swift`
- `PasswordReset/PasswordResetViewModel.swift`
- `Profile/ProfileViewModel.swift`

---

## Phase 2: Type Conversion & Extensions

### 2.1 Create Kotlin Type Conversion Extensions

**Problem**: Verbose type conversions scattered across ViewModels (~150 lines of boilerplate).

**Solution**: Create clean extensions for Swift-to-Kotlin type conversions.

**New File**: `iosApp/Extensions/KotlinTypeExtensions.swift`

```swift
import Foundation
import ComposeApp

// MARK: - Optional Bool to KotlinBoolean

extension Optional where Wrapped == Bool {
    var asKotlin: KotlinBoolean? {
        self.map { KotlinBoolean(bool: $0) }
    }
}

extension Bool {
    var asKotlin: KotlinBoolean {
        KotlinBoolean(bool: self)
    }
}

// MARK: - Optional Int to KotlinInt

extension Optional where Wrapped == Int {
    var asKotlin: KotlinInt? {
        self.map { KotlinInt(integerLiteral: $0) }
    }
}

extension Optional where Wrapped == Int32 {
    var asKotlin: KotlinInt? {
        self.map { KotlinInt(integerLiteral: Int($0)) }
    }
}

extension Int {
    var asKotlin: KotlinInt {
        KotlinInt(integerLiteral: self)
    }
}

extension Int32 {
    var asKotlin: KotlinInt {
        KotlinInt(integerLiteral: Int(self))
    }
}

// MARK: - Optional Double to KotlinDouble

extension Optional where Wrapped == Double {
    var asKotlin: KotlinDouble? {
        self.map { KotlinDouble(double: $0) }
    }
}

extension Double {
    var asKotlin: KotlinDouble {
        KotlinDouble(double: self)
    }
}

// MARK: - String to Optional Double (for form inputs)

extension String {
    var asOptionalDouble: Double? {
        Double(self)
    }

    var asKotlinDouble: KotlinDouble? {
        Double(self).map { KotlinDouble(double: $0) }
    }
}

// MARK: - Optional Long to KotlinLong

extension Optional where Wrapped == Int64 {
    var asKotlin: KotlinLong? {
        self.map { KotlinLong(longLong: $0) }
    }
}

extension Int64 {
    var asKotlin: KotlinLong {
        KotlinLong(longLong: self)
    }
}
```

**Files to Update** (simplify type conversions):
- `Documents/DocumentViewModel.swift`
- `Contractor/ContractorViewModel.swift`
- `Task/TaskViewModel.swift`
- `Residence/ResidenceViewModel.swift`

**Before**:
```swift
residenceId: residenceId != nil ? KotlinInt(integerLiteral: Int(residenceId!)) : nil,
isActive: isActive != nil ? KotlinBoolean(bool: isActive!) : nil,
```

**After**:
```swift
residenceId: residenceId.asKotlin,
isActive: isActive.asKotlin,
```

---

## Phase 3: State Management Improvements

### 3.1 Create Action State Pattern

**Problem**: `TaskViewModel` has 7 separate boolean flags for action states, which is error-prone.

**Solution**: Replace with a single enum-based state.

**New File**: `iosApp/Core/ActionState.swift`

```swift
import Foundation

/// Generic action state for tracking async operations
enum ActionState<T>: Equatable where T: Equatable {
    case idle
    case inProgress
    case success(T)
    case failure(String)

    var isInProgress: Bool {
        if case .inProgress = self { return true }
        return false
    }

    var isSuccess: Bool {
        if case .success = self { return true }
        return false
    }

    var successValue: T? {
        if case .success(let value) = self { return value }
        return nil
    }

    var errorMessage: String? {
        if case .failure(let message) = self { return message }
        return nil
    }

    static func == (lhs: ActionState<T>, rhs: ActionState<T>) -> Bool {
        switch (lhs, rhs) {
        case (.idle, .idle): return true
        case (.inProgress, .inProgress): return true
        case (.success(let l), .success(let r)): return l == r
        case (.failure(let l), .failure(let r)): return l == r
        default: return false
        }
    }
}

/// Specialized for void actions (create, delete, etc.)
typealias VoidActionState = ActionState<Void>

extension ActionState where T == Void {
    static var success: ActionState<Void> { .success(()) }
}

/// Task-specific action types
enum TaskActionType: Equatable {
    case created
    case updated
    case cancelled
    case uncancelled
    case markedInProgress
    case archived
    case unarchived
    case completed
}
```

**File to Update**: `Task/TaskViewModel.swift`

**Before**:
```swift
@Published var taskCreated: Bool = false
@Published var taskUpdated: Bool = false
@Published var taskCancelled: Bool = false
@Published var taskUncancelled: Bool = false
@Published var taskMarkedInProgress: Bool = false
@Published var taskArchived: Bool = false
@Published var taskUnarchived: Bool = false
```

**After**:
```swift
@Published var lastAction: ActionState<TaskActionType> = .idle

// Usage in views:
.onChange(of: viewModel.lastAction) { newValue in
    if case .success(let action) = newValue {
        switch action {
        case .created: // handle created
        case .cancelled: // handle cancelled
        // etc.
        }
        viewModel.lastAction = .idle // reset
    }
}
```

---

## Phase 4: Dependency Injection Foundation

### 4.1 Create Protocol Abstractions for Kotlin ViewModels

**Problem**: Hard-wired Kotlin ViewModel dependencies make unit testing impossible.

**Solution**: Create protocols that abstract the Kotlin layer, allowing mock implementations.

**New File**: `iosApp/Protocols/ViewModelProtocols.swift`

```swift
import Foundation
import ComposeApp

// MARK: - Residence ViewModel Protocol

protocol ResidenceViewModelProtocol {
    var myResidencesState: Kotlinx_coroutines_coreStateFlow { get }
    var createState: Kotlinx_coroutines_coreStateFlow { get }
    var updateState: Kotlinx_coroutines_coreStateFlow { get }
    var deleteState: Kotlinx_coroutines_coreStateFlow { get }

    func loadMyResidences(forceRefresh: Bool)
    func createResidence(request: ResidenceCreateRequest)
    func updateResidence(id: Int32, request: ResidenceUpdateRequest)
    func deleteResidence(id: Int32)
    func resetCreateState()
    func resetUpdateState()
    func resetDeleteState()
}

// Make Kotlin ViewModel conform
extension ComposeApp.ResidenceViewModel: ResidenceViewModelProtocol {}

// MARK: - Task ViewModel Protocol

protocol TaskViewModelProtocol {
    var kanbanState: Kotlinx_coroutines_coreStateFlow { get }
    var createState: Kotlinx_coroutines_coreStateFlow { get }
    var updateState: Kotlinx_coroutines_coreStateFlow { get }

    func loadKanbanBoard(residenceId: Int32, forceRefresh: Bool)
    func createTask(request: TaskCreateRequest)
    func updateTask(id: Int32, request: TaskUpdateRequest)
    func cancelTask(id: Int32)
    func markTaskInProgress(id: Int32)
    // ... other methods
}

extension ComposeApp.TaskViewModel: TaskViewModelProtocol {}

// MARK: - Auth ViewModel Protocol

protocol AuthViewModelProtocol {
    var loginState: Kotlinx_coroutines_coreStateFlow { get }
    var logoutState: Kotlinx_coroutines_coreStateFlow { get }

    func login(username: String, password: String)
    func logout()
    func resetLoginState()
}

extension ComposeApp.AuthViewModel: AuthViewModelProtocol {}
```

### 4.2 Create Simple Dependency Container

**New File**: `iosApp/Core/Dependencies.swift`

```swift
import Foundation
import ComposeApp

/// Simple dependency container for ViewModels
@MainActor
class Dependencies {
    static let shared = Dependencies()

    // MARK: - Kotlin ViewModel Factories

    func makeResidenceViewModel() -> ResidenceViewModelProtocol {
        ComposeApp.ResidenceViewModel()
    }

    func makeTaskViewModel() -> TaskViewModelProtocol {
        ComposeApp.TaskViewModel()
    }

    func makeAuthViewModel() -> AuthViewModelProtocol {
        ComposeApp.AuthViewModel()
    }

    func makeContractorViewModel() -> ComposeApp.ContractorViewModel {
        ComposeApp.ContractorViewModel()
    }

    func makeDocumentViewModel() -> ComposeApp.DocumentViewModel {
        ComposeApp.DocumentViewModel()
    }

    func makeProfileViewModel() -> ComposeApp.ProfileViewModel {
        ComposeApp.ProfileViewModel()
    }

    // MARK: - For Testing

    #if DEBUG
    static var testInstance: Dependencies?

    static var current: Dependencies {
        testInstance ?? shared
    }
    #else
    static var current: Dependencies { shared }
    #endif
}

// MARK: - Environment Key

private struct DependenciesKey: EnvironmentKey {
    static let defaultValue = Dependencies.shared
}

extension EnvironmentValues {
    var dependencies: Dependencies {
        get { self[DependenciesKey.self] }
        set { self[DependenciesKey.self] = newValue }
    }
}
```

**Updated ViewModel Pattern**:

```swift
@MainActor
class ResidenceViewModel: BaseViewModel {
    @Published var myResidences: MyResidencesResponse?

    private let sharedViewModel: ResidenceViewModelProtocol

    init(sharedViewModel: ResidenceViewModelProtocol? = nil) {
        self.sharedViewModel = sharedViewModel ?? Dependencies.current.makeResidenceViewModel()
        super.init()
    }

    func loadMyResidences(forceRefresh: Bool = false) {
        sharedViewModel.loadMyResidences(forceRefresh: forceRefresh)

        observe(sharedViewModel.myResidencesState) { [weak self] (response: MyResidencesResponse) in
            self?.myResidences = response
        } resetState: { [weak self] in
            // Reset if needed
        }
    }
}
```

---

## Phase 5: Multi-Step Flow Pattern (Optional Enhancement)

### 5.1 Create Multi-Step Flow Protocol

**Problem**: `PasswordResetViewModel` (315 lines) manages complex multi-step flow inline.

**Solution**: Extract reusable multi-step flow pattern.

**New File**: `iosApp/Core/MultiStepFlow.swift`

```swift
import Foundation
import SwiftUI

protocol MultiStepFlow: ObservableObject {
    associatedtype Step: Hashable & CaseIterable

    var currentStep: Step { get set }
    var canGoBack: Bool { get }
    var canGoForward: Bool { get }

    func goToNextStep()
    func goToPreviousStep()
    func reset()
}

extension MultiStepFlow where Step: CaseIterable, Step.AllCases: BidirectionalCollection {
    var canGoBack: Bool {
        currentStep != Step.allCases.first
    }

    var canGoForward: Bool {
        currentStep != Step.allCases.last
    }

    func goToNextStep() {
        let allCases = Array(Step.allCases)
        guard let currentIndex = allCases.firstIndex(of: currentStep),
              currentIndex < allCases.count - 1 else { return }
        currentStep = allCases[currentIndex + 1]
    }

    func goToPreviousStep() {
        let allCases = Array(Step.allCases)
        guard let currentIndex = allCases.firstIndex(of: currentStep),
              currentIndex > 0 else { return }
        currentStep = allCases[currentIndex - 1]
    }

    func reset() {
        currentStep = Step.allCases.first!
    }
}
```

---

## Phase 6: View Layer Refactoring

### 6.1 Create Reusable View Components

**Problem**: Views have heavy state management and duplicated patterns for loading, error handling, and form state.

**Solution**: Create composable view builders and state containers.

**New File**: `iosApp/Core/ViewState.swift`

```swift
import Foundation
import SwiftUI

/// Represents the state of async data loading
enum ViewState<T> {
    case idle
    case loading
    case loaded(T)
    case error(String)

    var isLoading: Bool {
        if case .loading = self { return true }
        return false
    }

    var data: T? {
        if case .loaded(let data) = self { return data }
        return nil
    }

    var errorMessage: String? {
        if case .error(let message) = self { return message }
        return nil
    }
}

/// Container for form field state
struct FormField<T> {
    var value: T
    var error: String?
    var isDirty: Bool = false

    mutating func validate(_ validator: (T) -> ValidationError?) {
        if let validationError = validator(value) {
            error = validationError.localizedDescription
        } else {
            error = nil
        }
    }

    mutating func touch() {
        isDirty = true
    }
}

extension FormField where T == String {
    init() {
        self.value = ""
        self.error = nil
        self.isDirty = false
    }
}
```

### 6.2 Create Loading State View Modifier

**New File**: `iosApp/Core/LoadingOverlay.swift`

```swift
import SwiftUI

struct LoadingOverlay: ViewModifier {
    let isLoading: Bool
    let message: String?

    func body(content: Content) -> some View {
        ZStack {
            content
                .disabled(isLoading)

            if isLoading {
                Color.black.opacity(0.3)
                    .ignoresSafeArea()

                VStack(spacing: 12) {
                    ProgressView()
                        .progressViewStyle(CircularProgressViewStyle(tint: .white))
                        .scaleEffect(1.2)

                    if let message = message {
                        Text(message)
                            .foregroundColor(.white)
                            .font(.subheadline)
                    }
                }
                .padding(24)
                .background(Color.black.opacity(0.7))
                .cornerRadius(12)
            }
        }
    }
}

extension View {
    func loadingOverlay(isLoading: Bool, message: String? = nil) -> some View {
        modifier(LoadingOverlay(isLoading: isLoading, message: message))
    }
}
```

### 6.3 Create Async Content View

**New File**: `iosApp/Core/AsyncContentView.swift`

```swift
import SwiftUI

/// Reusable view for handling async content states
struct AsyncContentView<T, Content: View, Loading: View, Error: View>: View {
    let state: ViewState<T>
    let content: (T) -> Content
    let loading: () -> Loading
    let error: (String, @escaping () -> Void) -> Error
    let onRetry: () -> Void

    init(
        state: ViewState<T>,
        @ViewBuilder content: @escaping (T) -> Content,
        @ViewBuilder loading: @escaping () -> Loading = { ProgressView() },
        @ViewBuilder error: @escaping (String, @escaping () -> Void) -> Error,
        onRetry: @escaping () -> Void
    ) {
        self.state = state
        self.content = content
        self.loading = loading
        self.error = error
        self.onRetry = onRetry
    }

    var body: some View {
        switch state {
        case .idle:
            EmptyView()
        case .loading:
            loading()
        case .loaded(let data):
            content(data)
        case .error(let message):
            error(message, onRetry)
        }
    }
}

// Convenience initializer with default error view
extension AsyncContentView where Error == DefaultErrorView {
    init(
        state: ViewState<T>,
        @ViewBuilder content: @escaping (T) -> Content,
        @ViewBuilder loading: @escaping () -> Loading = { ProgressView() },
        onRetry: @escaping () -> Void
    ) {
        self.state = state
        self.content = content
        self.loading = loading
        self.error = { message, retry in DefaultErrorView(message: message, onRetry: retry) }
        self.onRetry = onRetry
    }
}

struct DefaultErrorView: View {
    let message: String
    let onRetry: () -> Void

    var body: some View {
        VStack(spacing: 16) {
            Image(systemName: "exclamationmark.triangle")
                .font(.largeTitle)
                .foregroundColor(.red)

            Text(message)
                .multilineTextAlignment(.center)
                .foregroundColor(.secondary)

            Button("Retry", action: onRetry)
                .buttonStyle(.bordered)
        }
        .padding()
    }
}
```

### 6.4 Refactor Form Views Pattern

**Problem**: Form views like `CompleteTaskView` have 12+ `@State` properties.

**Solution**: Use form state containers.

**Example Refactoring** (CompleteTaskView):

**Before**:
```swift
struct CompleteTaskView: View {
    @State private var completedByName: String = ""
    @State private var actualCost: String = ""
    @State private var notes: String = ""
    @State private var rating: Int = 3
    @State private var selectedItems: [PhotosPickerItem] = []
    @State private var selectedImages: [UIImage] = []
    @State private var completionDate: Date = Date()
    @State private var showingImagePicker: Bool = false
    @State private var isSubmitting: Bool = false
    @State private var errorMessage: String?
    // ... more state
}
```

**After**:
```swift
struct CompleteTaskFormState {
    var completedByName = FormField<String>()
    var actualCost = FormField<String>()
    var notes = FormField<String>()
    var rating: Int = 3
    var completionDate: Date = Date()
    var selectedImages: [UIImage] = []

    var isValid: Bool {
        completedByName.error == nil && actualCost.error == nil
    }

    mutating func validateAll() {
        completedByName.validate { ValidationRules.validateRequired($0, fieldName: "Completed By") }
    }
}

struct CompleteTaskView: View {
    @State private var formState = CompleteTaskFormState()
    @StateObject private var viewModel: TaskViewModel
    // Reduced from 12+ to 2 state properties
}
```

### 6.5 Views to Refactor

| View File | Current State Props | Target | Changes |
|-----------|-------------------|--------|---------|
| `Task/CompleteTaskView.swift` | 12+ | 2-3 | Extract form state |
| `Task/AddTaskView.swift` | 10+ | 2-3 | Extract form state |
| `Task/EditTaskView.swift` | 10+ | 2-3 | Extract form state |
| `Residence/AddResidenceView.swift` | 8+ | 2-3 | Extract form state |
| `Residence/EditResidenceView.swift` | 8+ | 2-3 | Extract form state |
| `Contractor/AddContractorView.swift` | 6+ | 2-3 | Extract form state |
| `Documents/AddDocumentView.swift` | 8+ | 2-3 | Extract form state |
| `Login/LoginView.swift` | 5 | 2 | Use AsyncContentView |
| `Residence/ResidencesListView.swift` | 5 | 2 | Use AsyncContentView |

---

## Implementation Order

### Session 1: Core Abstractions (Highest Impact)

1. **Create Core/ folder and new files**:
   - `iosApp/Core/StateFlowObserver.swift`
   - `iosApp/Core/BaseViewModel.swift`
   - `iosApp/Core/ValidationRules.swift`

2. **Refactor ViewModels to use StateFlowObserver**:
   - Start with `ResidenceViewModel` as the template
   - Apply pattern to remaining 9 ViewModels

3. **Migrate ViewModels to inherit from BaseViewModel**

### Session 2: Type Conversions & Extensions

1. **Create new file**:
   - `iosApp/Core/Extensions/KotlinTypeExtensions.swift`

2. **Update ViewModels to use new extensions**:
   - `DocumentViewModel` (heaviest user)
   - `ContractorViewModel`
   - `TaskViewModel`
   - `ResidenceViewModel`

### Session 3: State Management

1. **Create new file**:
   - `iosApp/Core/ActionState.swift`

2. **Refactor TaskViewModel**:
   - Replace 7 boolean flags with `ActionState<TaskActionType>`
   - Update all views that observe these flags

3. **Apply pattern to other ViewModels** (ContractorViewModel, DocumentViewModel)

### Session 4: Dependency Injection

1. **Create new files**:
   - `iosApp/Core/Protocols/ViewModelProtocols.swift`
   - `iosApp/Core/Dependencies.swift`

2. **Update ViewModels to accept protocol-based dependencies**

3. **Verify testability** with sample mock

### Session 5: View Layer Refactoring

1. **Create new files**:
   - `iosApp/Core/ViewState.swift`
   - `iosApp/Core/LoadingOverlay.swift`
   - `iosApp/Core/AsyncContentView.swift`

2. **Create form state structs** for each form view:
   - `CompleteTaskFormState`
   - `AddTaskFormState`
   - `AddResidenceFormState`
   - etc.

3. **Refactor form views** to use new state containers

4. **Update list views** to use `AsyncContentView` pattern

---

## Files Summary

### New Files to Create (11 files in Core/)

| File | Purpose | Priority |
|------|---------|----------|
| `Core/StateFlowObserver.swift` | Reusable StateFlow observation | P0 |
| `Core/BaseViewModel.swift` | Common ViewModel base class | P0 |
| `Core/ValidationRules.swift` | Centralized validation | P0 |
| `Core/Extensions/KotlinTypeExtensions.swift` | Type conversion helpers | P1 |
| `Core/ActionState.swift` | Action state enum | P1 |
| `Core/Protocols/ViewModelProtocols.swift` | Kotlin ViewModel abstractions | P2 |
| `Core/Dependencies.swift` | Simple DI container (factory pattern) | P2 |
| `Core/MultiStepFlow.swift` | Multi-step flow protocol | P3 |
| `Core/ViewState.swift` | View state enum + FormField | P2 |
| `Core/LoadingOverlay.swift` | Loading overlay modifier | P2 |
| `Core/AsyncContentView.swift` | Async content wrapper view | P2 |

### Files to Modify (10 ViewModels)

| File | Changes | Impact |
|------|---------|--------|
| `Residence/ResidenceViewModel.swift` | Inherit BaseViewModel, use StateFlowObserver | High |
| `Task/TaskViewModel.swift` | Replace boolean flags, use ActionState | High |
| `Contractor/ContractorViewModel.swift` | Use StateFlowObserver, type extensions | Medium |
| `Documents/DocumentViewModel.swift` | Heavy type conversion cleanup | High |
| `Login/LoginViewModel.swift` | Extract validation, use base class | Medium |
| `Profile/ProfileViewModel.swift` | Minor cleanup | Low |
| `Register/RegisterView.swift` | Extract validation | Low |
| `VerifyEmail/VerifyEmailViewModel.swift` | Use StateFlowObserver | Low |
| `PasswordReset/PasswordResetViewModel.swift` | Validation, possibly MultiStepFlow | Medium |

### Views to Modify (9 form/list views)

| File | Changes | Impact |
|------|---------|--------|
| `Task/CompleteTaskView.swift` | Extract form state | High |
| `Task/AddTaskView.swift` | Extract form state | High |
| `Task/EditTaskView.swift` | Extract form state | Medium |
| `Residence/AddResidenceView.swift` | Extract form state | Medium |
| `Residence/EditResidenceView.swift` | Extract form state | Medium |
| `Residence/ResidencesListView.swift` | Use AsyncContentView | Medium |
| `Contractor/AddContractorView.swift` | Extract form state | Low |
| `Documents/AddDocumentView.swift` | Extract form state | Low |
| `Login/LoginView.swift` | Use AsyncContentView | Low |

---

## Expected Outcomes

| Metric | Before | After | Improvement |
|--------|--------|-------|-------------|
| Total Lines | ~13,837 | ~11,800 | -15% |
| Duplicated Patterns | 26+ | 0 | -100% |
| ViewModel Boilerplate | ~200 lines each | ~80 lines each | -60% |
| View State Properties | 8-12 per form | 2-3 per form | -75% |
| Type Conversion Lines | ~150 | ~30 | -80% |
| Unit Test Coverage | 0% | Possible | Enabled |
| Validation Sources | 4+ files | 1 file | Centralized |

---

## Risk Mitigation

1. **Incremental Approach**: Each phase is independently deployable
2. **Template First**: Refactor `ResidenceViewModel` completely as template before others
3. **Testing**: Run app after each ViewModel refactor to catch regressions
4. **Git Strategy**: Commit after each major refactor step
5. **View Testing**: Test each form after state extraction to ensure bindings work

---

## Final Core/ Folder Structure

```
iosApp/Core/
├── StateFlowObserver.swift      # Kotlin StateFlow observation utility
├── BaseViewModel.swift          # Base class for all ViewModels
├── ValidationRules.swift        # Centralized validation logic
├── ActionState.swift            # Generic action state enum
├── ViewState.swift              # View state + FormField
├── LoadingOverlay.swift         # Loading overlay modifier
├── AsyncContentView.swift       # Async content wrapper
├── MultiStepFlow.swift          # Multi-step flow protocol
├── Dependencies.swift           # Simple factory-based DI
├── Extensions/
│   └── KotlinTypeExtensions.swift
└── Protocols/
    └── ViewModelProtocols.swift
```