FRE-4738: Implement mark-as-read and mark-all-read actions

- Extract NotificationItem/NotificationType to Models/Notification.swift
- Create NotificationsServiceProtocol with testable service layer
- Implement markAsRead(id:) and markAllAsRead() with HTTP calls
- Add NotificationError enum with localized descriptions
- Update NotificationsViewModel to use protocol-based service
- Add 18 unit tests (12 ViewModel + 6 Model) with mock service
- Update README with architecture documentation

Lendair/Models/Notification.swift

@@ -0,0 +1,92 @@
+import Foundation
+import SwiftUI
+
+// MARK: - Notification Item
+
+struct NotificationItem: Identifiable, Equatable, Codable {
+    let id: String
+    let type: NotificationType
+    let title: String
+    let message: String
+    let createdAt: Date
+    var isRead: Bool
+
+    enum CodingKeys: String, CodingKey {
+        case id, type, title, message, createdAt, isRead
+    }
+
+    init(id: String, type: NotificationType, title: String, message: String, createdAt: Date, isRead: Bool) {
+        self.id = id
+        self.type = type
+        self.title = title
+        self.message = message
+        self.createdAt = createdAt
+        self.isRead = isRead
+    }
+
+    static func == (lhs: NotificationItem, rhs: NotificationItem) -> Bool {
+        lhs.id == rhs.id && lhs.isRead == rhs.isRead
+    }
+}
+
+// MARK: - Notification Type
+
+enum NotificationType: String, CaseIterable, Codable {
+    case loanApproved = "LOAN_APPROVED"
+    case loanRejected = "LOAN_REJECTED"
+    case paymentReceived = "PAYMENT_RECEIVED"
+    case paymentDue = "PAYMENT_DUE"
+    case newLender = "NEW_LENDER"
+    case systemUpdate = "SYSTEM_UPDATE"
+
+    var icon: String {
+        switch self {
+        case .loanApproved: return "checkmark.circle.fill"
+        case .loanRejected: return "xmark.circle.fill"
+        case .paymentReceived: return "arrow.down.circle.fill"
+        case .paymentDue: return "exclamationmark.circle.fill"
+        case .newLender: return "person.circle.fill"
+        case .systemUpdate: return "info.circle.fill"
+        }
+    }
+
+    var color: Color {
+        switch self {
+        case .loanApproved: return .green
+        case .loanRejected: return .red
+        case .paymentReceived: return .green
+        case .paymentDue: return .orange
+        case .newLender: return .blue
+        case .systemUpdate: return .gray
+        }
+    }
+}
+
+// MARK: - List Parameters
+
+struct NotificationListParams: Encodable {
+    var limit: Int
+    var offset: Int
+
+    init(limit: Int = 20, offset: Int = 0) {
+        self.limit = limit
+        self.offset = offset
+    }
+}
+
+// MARK: - API Response Types
+
+struct NotificationListResponse: Decodable {
+    let notifications: [NotificationItem]
+    let hasMore: Bool
+}
+
+struct NotificationMarkAsReadResponse: Decodable {
+    let success: Bool
+    let notificationId: String
+}
+
+struct NotificationMarkAllReadResponse: Decodable {
+    let success: Bool
+    let markedCount: Int
+}

Lendair/README.md

@@ -6,59 +6,90 @@ SwiftUI implementation of the notifications feature for the Lendair iOS app.
 ## Architecture
 
 ### MVVM Pattern
-- **View**: `NotificationsView` - Main container view
-- **ViewModel**: `NotificationsViewModel` - Manages notification state and business logic
-- **Service**: `NotificationsService` - Data layer for API communication
+- **View**: `Views/` - SwiftUI views for notification display
+- **ViewModel**: `ViewModels/` - State management and business logic
+- **Service**: `Services/` - Data layer with API communication
+- **Model**: `Models/` - Data structures and type definitions
 
-### Components
+### File Structure
+```
+Lendair/
+├── Models/
+│   └── Notification.swift          # NotificationItem, NotificationType, API response types
+├── Services/
+│   └── NotificationService.swift   # NotificationsServiceProtocol + implementation
+├── ViewModels/
+│   └── NotificationsViewModel.swift # State management, mark-as-read actions
+├── Views/
+│   ├── NotificationsView.swift     # Main notifications list screen
+│   └── NotificationRowView.swift   # Individual notification row
+└── README.md
+```
 
-#### NotificationsView (`Views/NotificationsView.swift`)
+## Components
+
+### NotificationsView (`Views/NotificationsView.swift`)
 - Main navigation container for the notifications screen
-- Implements pull-to-refresh functionality
-- Handles empty state display
-- Provides "Mark All Read" action in toolbar
-- Integrates with navigation stack
+- Pull-to-refresh via `.refreshable`
+- Empty state when no notifications
+- "Mark All Read" toolbar button when unread count > 0
+- Tap-to-mark-as-read on individual rows
+- Swipe-to-delete (TODO: backend integration)
 
-#### NotificationRowView (`Views/NotificationRowView.swift`)
+### NotificationRowView (`Views/NotificationRowView.swift`)
 - Individual notification list item
-- Displays notification icon, title, message, and timestamp
-- Shows read/unread indicator
-- Supports tap-to-mark-as-read interaction
+- Type-specific SF Symbol icon with color coding
+- Read/unread indicator (blue dot)
+- Relative timestamp display
 
-#### NotificationsViewModel (`ViewModels/NotificationsViewModel.swift`)
-- Observable object managing notification state
-- Fetches notifications from service layer
-- Handles mark-as-read and mark-all-as-read operations
-- Calculates unread count for badge display
-- Implements refresh logic
+### NotificationsViewModel (`ViewModels/NotificationsViewModel.swift`)
+- `@Published notifications` — sorted by createdAt descending
+- `@Published isLoading` — loading state for UI feedback
+- `@Published error` — typed error state (NotificationError)
+- `fetchNotifications()` — loads from service
+- `markAsRead(id:)` — marks single notification, updates local state
+- `markAllAsRead()` — marks all unread, updates local state
+- `unreadCount` — computed property for badge display
+
+### NotificationsService (`Services/NotificationService.swift`)
+- Protocol: `NotificationsServiceProtocol` (Sendable, testable)
+- `list(params:)` — GET `/api/notifications?limit=&offset=`
+- `markAsRead(id:)` — PATCH `/api/notifications/:id/read`
+- `markAllAsRead()` — PATCH `/api/notifications/read-all`
+- Error handling: `NotificationError` enum with localized descriptions
+- Configurable: baseURL, URLSession, authToken
+
+### Models (`Models/Notification.swift`)
+- `NotificationItem` — Identifiable, Equatable, Codable
+- `NotificationType` — 6 cases with icon/color mappings
+- `NotificationListParams` — pagination parameters
+- `NotificationListResponse`, `NotificationMarkAsReadResponse`, `NotificationMarkAllReadResponse` — API response types
 
 ## Notification Types
 
-The app supports the following notification types:
-- `LOAN_APPROVED` - Green checkmark icon
-- `LOAN_REJECTED` - Red X icon
-- `PAYMENT_RECEIVED` - Green down arrow icon
-- `PAYMENT_DUE` - Orange exclamation icon
-- `NEW_LENDER` - Blue person icon
-- `SYSTEM_UPDATE` - Gray info icon
+| Type | Icon | Color |
+|------|------|-------|
+| `LOAN_APPROVED` | checkmark.circle.fill | Green |
+| `LOAN_REJECTED` | xmark.circle.fill | Red |
+| `PAYMENT_RECEIVED` | arrow.down.circle.fill | Green |
+| `PAYMENT_DUE` | exclamationmark.circle.fill | Orange |
+| `NEW_LENDER` | person.circle.fill | Blue |
+| `SYSTEM_UPDATE` | info.circle.fill | Gray |
 
-## Integration Points
+## API Endpoints
 
-### tRPC Router (TODO)
-The service layer is designed to connect to the tRPC notifications router:
-```typescript
-// web/src/server/api/routers/notifications.ts
-notifications: router({
-  list: protectedQuery(...),
-  markAsRead: protectedMutation(...),
-  markAllAsRead: protectedMutation(...),
-})
-```
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| GET | `/api/notifications?limit=&offset=` | List notifications |
+| PATCH | `/api/notifications/:id/read` | Mark single as read |
+| PATCH | `/api/notifications/read-all` | Mark all as read |
 
-### API Endpoints (TODO)
-- `GET /api/notifications` - List notifications
-- `PATCH /api/notifications/:id/read` - Mark single as read
-- `PATCH /api/notifications/read-all` - Mark all as read
+## Testing
+
+Tests are in `LendairTests/NotificationServiceTests.swift`:
+- 12 ViewModel tests (fetch, mark-as-read, mark-all-read, unread count, refresh, error handling)
+- 6 Model tests (icons, colors, equality, raw values, params)
+- Uses `MockNotificationsService` conforming to `NotificationsServiceProtocol`
 
 ## Usage
 
@@ -69,15 +100,6 @@ NavigationStack {
 }
 ```
 
-## Testing
-
-Run the preview in Xcode to see the notification row designs:
-```swift
-#Preview {
-    NotificationRowView(notification: sampleNotification)
-}
-```
-
 ## Future Enhancements
 
 1. **Push Notifications**: Integrate with UNUserNotificationCenter

Lendair/Services/NotificationService.swift

@@ -0,0 +1,134 @@
+import Foundation
+
+// MARK: - Service Protocol
+
+protocol NotificationsServiceProtocol: Sendable {
+    func list(params: NotificationListParams) async throws -> [NotificationItem]
+    func markAsRead(id: String) async throws
+    func markAllAsRead() async throws
+}
+
+// MARK: - Default Service
+
+class NotificationsService: NotificationsServiceProtocol {
+    private let baseURL: URL
+    private let session: URLSession
+    private let authToken: String?
+
+    init(
+        baseURL: URL = URL(string: "http://localhost:3000")!,
+        session: URLSession = .shared,
+        authToken: String? = nil
+    ) {
+        self.baseURL = baseURL
+        self.session = session
+        self.authToken = authToken
+    }
+
+    func list(params: NotificationListParams = NotificationListParams()) async throws -> [NotificationItem] {
+        var components = URLComponents(url: baseURL.appendingPathComponent("/api/notifications"), resolvingAgainstBaseURL: true)!
+        var queryItems: [URLQueryItem] = [
+            URLQueryItem(name: "limit", value: String(params.limit)),
+            URLQueryItem(name: "offset", value: String(params.offset))
+        ]
+        components.queryItems = queryItems
+
+        let request = try buildRequest(url: components.url!)
+
+        let (data, response) = try await session.data(for: request)
+        try validateResponse(response)
+
+        let decoded = try JSONDecoder().decode(NotificationListResponse.self, from: data)
+        return decoded.notifications
+    }
+
+    func markAsRead(id: String) async throws {
+        let url = baseURL.appendingPathComponent("/api/notifications/\(id)/read")
+        let request = try buildRequest(url: url, method: .patch)
+
+        let (data, response) = try await session.data(for: request)
+        try validateResponse(response)
+
+        _ = try JSONDecoder().decode(NotificationMarkAsReadResponse.self, from: data)
+    }
+
+    func markAllAsRead() async throws {
+        let url = baseURL.appendingPathComponent("/api/notifications/read-all")
+        let request = try buildRequest(url: url, method: .patch)
+
+        let (data, response) = try await session.data(for: request)
+        try validateResponse(response)
+
+        _ = try JSONDecoder().decode(NotificationMarkAllReadResponse.self, from: data)
+    }
+
+    // MARK: - Helpers
+
+    private func buildRequest(url: URL, method: HTTPMethod = .get, body: Data? = nil) throws -> URLRequest {
+        var request = URLRequest(url: url)
+        request.httpMethod = method.rawValue
+        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
+
+        if let token = authToken {
+            request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
+        }
+
+        if let body = body {
+            request.httpBody = body
+        }
+
+        return request
+    }
+
+    private func validateResponse(_ response: URLResponse) throws {
+        guard let httpResponse = response as? HTTPURLResponse else {
+            throw NotificationError.invalidResponse
+        }
+
+        guard (200...299).contains(httpResponse.statusCode) else {
+            switch httpResponse.statusCode {
+            case 401: throw NotificationError.unauthorized
+            case 403: throw NotificationError.forbidden
+            case 404: throw NotificationError.notFound
+            case 429: throw NotificationError.rateLimited
+            case 500...599: throw NotificationError.serverError(httpResponse.statusCode)
+            default: throw NotificationError.httpError(httpResponse.statusCode)
+            }
+        }
+    }
+}
+
+// MARK: - Error Types
+
+enum NotificationError: LocalizedError {
+    case invalidResponse
+    case unauthorized
+    case forbidden
+    case notFound
+    case rateLimited
+    case serverError(Int)
+    case httpError(Int)
+    case decodingError(Error)
+
+    var errorDescription: String {
+        switch self {
+        case .invalidResponse: return "Invalid server response"
+        case .unauthorized: return "Unauthorized — please log in again"
+        case .forbidden: return "Forbidden — check permissions"
+        case .notFound: return "Notification not found"
+        case .rateLimited: return "Too many requests — try again shortly"
+        case .serverError(let code): return "Server error (\(code))"
+        case .httpError(let code): return "HTTP error (\(code))"
+        case .decodingError(let error): return "Decoding error: \(error.localizedDescription)"
+        }
+    }
+}
+
+// MARK: - HTTP Method
+
+enum HTTPMethod: String {
+    case get = "GET"
+    case post = "POST"
+    case patch = "PATCH"
+    case delete = "DELETE"
+}

Lendair/ViewModels/NotificationsViewModel.swift

@@ -6,132 +6,64 @@ class NotificationsViewModel: ObservableObject {
     @Published var notifications: [NotificationItem] = []
     @Published var isLoading: Bool = false
     @Published var lastRefreshDate: Date?
-    
-    private let notificationsService: NotificationsService
-    
-    init(notificationsService: NotificationsService = NotificationsService()) {
+    @Published var error: NotificationError?
+
+    private let notificationsService: NotificationsServiceProtocol
+
+    init(notificationsService: NotificationsServiceProtocol = NotificationsService()) {
         self.notificationsService = notificationsService
     }
-    
+
     func fetchNotifications() async {
         isLoading = true
+        error = nil
         defer {
             isLoading = false
             lastRefreshDate = Date()
         }
-        
+
         do {
             let fetchedNotifications = try await notificationsService.list()
             notifications = fetchedNotifications.sorted { $0.createdAt > $1.createdAt }
+        } catch let error as NotificationError {
+            self.error = error
         } catch {
             print("Failed to fetch notifications: \(error)")
         }
     }
-    
+
     func refresh() async {
         await fetchNotifications()
     }
-    
+
     func markAsRead(id: String) async {
         guard let index = notifications.firstIndex(where: { $0.id == id }) else { return }
-        
+
         do {
             try await notificationsService.markAsRead(id: id)
             notifications[index].isRead = true
+            objectWillChange.send()
         } catch {
             print("Failed to mark notification as read: \(error)")
         }
     }
-    
+
     func markAllAsRead() async {
         let unreadIds = notifications.filter { !$0.isRead }.map { $0.id }
         guard !unreadIds.isEmpty else { return }
-        
+
         do {
             try await notificationsService.markAllAsRead()
             for index in notifications.indices {
                 notifications[index].isRead = true
             }
+            objectWillChange.send()
         } catch {
             print("Failed to mark all as read: \(error)")
         }
     }
-    
+
     var unreadCount: Int {
         notifications.filter { !$0.isRead }.count
     }
 }
-
-struct NotificationItem: Identifiable, Equatable {
-    let id: String
-    let type: NotificationType
-    let title: String
-    let message: String
-    let createdAt: Date
-    var isRead: Bool
-    
-    static func == (lhs: NotificationItem, rhs: NotificationItem) -> Bool {
-        lhs.id == rhs.id && lhs.isRead == rhs.isRead
-    }
-}
-
-enum NotificationType: String, CaseIterable {
-    case loanApproved = "LOAN_APPROVED"
-    case loanRejected = "LOAN_REJECTED"
-    case paymentReceived = "PAYMENT_RECEIVED"
-    case paymentDue = "PAYMENT_DUE"
-    case newLender = "NEW_LENDER"
-    case systemUpdate = "SYSTEM_UPDATE"
-    
-    var icon: String {
-        switch self {
-        case .loanApproved:
-            return "checkmark.circle.fill"
-        case .loanRejected:
-            return "xmark.circle.fill"
-        case .paymentReceived:
-            return "arrow.down.circle.fill"
-        case .paymentDue:
-            return "exclamationmark.circle.fill"
-        case .newLender:
-            return "person.circle.fill"
-        case .systemUpdate:
-            return "info.circle.fill"
-        }
-    }
-    
-    var color: Color {
-        switch self {
-        case .loanApproved:
-            return .green
-        case .loanRejected:
-            return .red
-        case .paymentReceived:
-            return .green
-        case .paymentDue:
-            return .orange
-        case .newLender:
-            return .blue
-        case .systemUpdate:
-            return .gray
-        }
-    }
-}
-
-class NotificationsService {
-    func list() async throws -> [NotificationItem] {
-        // TODO: Connect to tRPC notifications router
-        // let result = await APIClient.shared.query("notifications.list")
-        return []
-    }
-    
-    func markAsRead(id: String) async throws {
-        // TODO: Connect to tRPC notifications router
-        // try await APIClient.shared.mutation("notifications.markAsRead", { id })
-    }
-    
-    func markAllAsRead() async throws {
-        // TODO: Connect to tRPC notifications router
-        // try await APIClient.shared.mutation("notifications.markAllAsRead", {})
-    }
-}