diff --git a/IosClientKit/Sources/FeatureAuth/AuthScreen.swift b/IosClientKit/Sources/FeatureAuth/AuthScreen.swift
index c1f3cd3..2946e0a 100644
--- a/IosClientKit/Sources/FeatureAuth/AuthScreen.swift
+++ b/IosClientKit/Sources/FeatureAuth/AuthScreen.swift
@@ -1,10 +1,100 @@
 import SwiftUI
+import DesignSystem
 
-/// FeatureAuth 占位（后续实现登录 / 注册）。
 public struct AuthScreen: View {
-    public init() {}
+    private let viewModel: AuthViewModel
+    private let onLoggedIn: () -> Void
+
+    @State private var phone = ""
+    @State private var code = ""
+    @State private var privacyAgreed = false
+
+    @Environment(\.dismiss) private var dismiss
+
+    public init(viewModel: AuthViewModel, onLoggedIn: @escaping () -> Void) {
+        self.viewModel = viewModel
+        self.onLoggedIn = onLoggedIn
+    }
 
     public var body: some View {
-        ContentUnavailableView("登录", systemImage: "person.crop.circle")
+        NavigationStack {
+            ScrollView {
+                VStack(alignment: .leading, spacing: DS.Spacing.md) {
+                    Text("手机号登录")
+                        .font(.title2.bold())
+                        .foregroundStyle(DS.Color.brandDark)
+                    Text("手机号仅用于账号绑定，不会公开展示")
+                        .font(.footnote)
+                        .foregroundStyle(DS.Color.faintText)
+
+                    TextField("手机号", text: Binding(get: { phone }, set: { phone = digits($0, max: 11) }))
+                        .textFieldStyle(.roundedBorder)
+
+                    HStack(spacing: DS.Spacing.sm) {
+                        TextField("验证码", text: Binding(get: { code }, set: { code = digits($0, max: 6) }))
+                            .textFieldStyle(.roundedBorder)
+                        Button(getCodeTitle) { viewModel.requestSmsCode(phone: phone) }
+                            .buttonStyle(.bordered)
+                            .disabled(!canSendCode)
+                    }
+
+                    Button { privacyAgreed.toggle() } label: {
+                        HStack(spacing: DS.Spacing.xs) {
+                            Image(systemName: privacyAgreed ? "checkmark.square.fill" : "square")
+                                .foregroundStyle(privacyAgreed ? DS.Color.brandGold : DS.Color.brandMuted)
+                            Text("我已阅读并同意《用户协议》和《隐私政策》")
+                                .font(.caption)
+                                .foregroundStyle(DS.Color.faintText)
+                        }
+                    }
+                    .buttonStyle(.plain)
+
+                    if let errorMessage = viewModel.errorMessage {
+                        Text(errorMessage)
+                            .font(.footnote)
+                            .foregroundStyle(DS.Color.danger)
+                    }
+
+                    Button(viewModel.isSubmitting ? "登录中..." : "登录") {
+                        viewModel.login(phone: phone, code: code)
+                    }
+                    .buttonStyle(.borderedProminent)
+                    .frame(maxWidth: .infinity)
+                    .disabled(!canSubmit)
+                }
+                .padding(DS.Spacing.lg)
+            }
+            .navigationTitle("登录")
+            .toolbar {
+                ToolbarItem(placement: .cancellationAction) {
+                    Button("取消") { dismiss() }
+                }
+            }
+        }
+        .onChange(of: viewModel.didLogin) { _, loggedIn in
+            if loggedIn { onLoggedIn() }
+        }
+    }
+
+    private var phoneValid: Bool {
+        phone.range(of: #"^1\d{10}$"#, options: .regularExpression) != nil
+    }
+
+    private var canSendCode: Bool {
+        phoneValid && viewModel.countdownSeconds == 0 && !viewModel.isSendingCode
+    }
+
+    private var canSubmit: Bool {
+        phoneValid && !code.isEmpty && privacyAgreed && !viewModel.isSubmitting
+    }
+
+    private var getCodeTitle: String {
+        if viewModel.countdownSeconds > 0 { return "\(viewModel.countdownSeconds)s 后重发" }
+        if viewModel.isSendingCode { return "发送中" }
+        return "获取验证码"
+    }
+
+    private func digits(_ string: String, max: Int) -> String {
+        String(string.filter(\.isNumber).prefix(max))
     }
 }
diff --git a/IosClientKit/Sources/FeatureAuth/AuthViewModel.swift b/IosClientKit/Sources/FeatureAuth/AuthViewModel.swift
new file mode 100644
index 0000000..e77f16f
--- /dev/null
+++ b/IosClientKit/Sources/FeatureAuth/AuthViewModel.swift
@@ -0,0 +1,65 @@
+import CoreDomain
+import Foundation
+import Observation
+
+@MainActor
+@Observable
+public final class AuthViewModel {
+    public var isSendingCode = false
+    public var countdownSeconds = 0
+    public var isSubmitting = false
+    public var errorMessage: String?
+    public var didLogin = false
+
+    private let sessionUseCase: SessionUseCase
+    private var countdownTask: Task<Void, Never>?
+
+    public init(sessionUseCase: SessionUseCase) {
+        self.sessionUseCase = sessionUseCase
+    }
+
+    public func requestSmsCode(phone: String) {
+        guard !isSendingCode, countdownSeconds == 0 else { return }
+        isSendingCode = true
+        errorMessage = nil
+        Task { [weak self] in
+            guard let self else { return }
+            do {
+                try await self.sessionUseCase.requestSmsCode(phone: phone)
+                self.startCountdown()
+            } catch {
+                self.errorMessage = (error as? LocalizedError)?.errorDescription ?? error.localizedDescription
+            }
+            self.isSendingCode = false
+        }
+    }
+
+    public func login(phone: String, code: String) {
+        guard !isSubmitting else { return }
+        isSubmitting = true
+        errorMessage = nil
+        Task { [weak self] in
+            guard let self else { return }
+            do {
+                try await self.sessionUseCase.login(phone: phone, code: code)
+                self.didLogin = true
+            } catch {
+                self.errorMessage = (error as? LocalizedError)?.errorDescription ?? error.localizedDescription
+            }
+            self.isSubmitting = false
+        }
+    }
+
+    private func startCountdown() {
+        countdownTask?.cancel()
+        countdownSeconds = 60
+        countdownTask = Task { [weak self] in
+            guard let self else { return }
+            while self.countdownSeconds > 0 {
+                try? await Task.sleep(for: .seconds(1))
+                guard !Task.isCancelled else { return }
+                self.countdownSeconds -= 1
+            }
+        }
+    }
+}