[#763] Google 인증을 GoogleSignIn serverAuthCode 흐름으로 전환한다

Application/App/Sources/App/Delegate/AppDelegate.swift

@@ -15,6 +15,15 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
     private let logger = Logger(category: "AppDelegate")
     private let container = AppDIContainer.shared
 
+    // Google 로그인 URL 콜백 처리
+    func application(
+        _ app: UIApplication,
+        open url: URL,
+        options: [UIApplication.OpenURLOptionsKey: Any] = [:]
+    ) -> Bool {
+        GoogleSignInURLHandler.handle(url)
+    }
+
     func application(
         _ application: UIApplication,
         didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil

Application/App/Sources/Resource/Info.plist

@@ -31,6 +31,7 @@
 			<string>Editor</string>
 			<key>CFBundleURLSchemes</key>
 			<array>
+				<string>$(REVERSED_CLIENT_ID)</string>
 				<string>DevLog</string>
 			</array>
 		</dict>
@@ -53,6 +54,10 @@
 	<string>$(FIRESTORE_DATABASE_ID)</string>
 	<key>FUNCTION_API_BASE_URL</key>
 	<string>$(FUNCTION_API_BASE_URL)</string>
+	<key>GIDClientID</key>
+	<string>$(CLIENT_ID)</string>
+	<key>GIDServerClientID</key>
+	<string>$(GID_SERVER_CLIENT_ID)</string>
 	<key>ITSAppUsesNonExemptEncryption</key>
 	<false/>
 	<key>LSApplicationCategoryType</key>

Application/Core/Sources/Authentication/AuthPresentationContext.swift

@@ -0,0 +1,17 @@
+//
+//  AuthPresentationContext.swift
+//  Core
+//
+//  Created by opfic on 7/27/26.
+//
+
+public struct AuthPresentationContext: Equatable, Sendable {
+    public let identifier: String
+
+    // 인증 호출 경로에서 같은 key로 접근하되 실제 값은 각 Task에 격리하기 위한 정적 변수
+    @TaskLocal public static var current: Self?
+
+    public init(identifier: String) {
+        self.identifier = identifier
+    }
+}

Application/Data/Sources/Protocol/AuthenticationService.swift

@@ -9,7 +9,7 @@ import Foundation
 
 public protocol AuthenticationService {
     func signIn() async throws -> AuthDataResponse?
-    func signOut(_ uid: String) async throws
+    func clearLocalSession()
     func deleteAuth(_ uid: String) async throws
     func link(uid: String) async throws -> Bool
     func unlink(_ uid: String) async throws

Application/Data/Sources/Repository/AuthenticationRepositoryImpl.swift

@@ -64,32 +64,15 @@ final class AuthenticationRepositoryImpl: AuthenticationRepository {
     }
 
     func signOut() async throws {
-        guard let uid = authService.uid,
-              let providerID = try await authService.getProviderID(),
-              let provider = AuthProvider(rawValue: providerID)
-        else {
-            try await authService.clearCurrentSession()
-            widgetSnapshotUpdater.clear()
-            return
-        }
+        let providers = authService.providerIDs.compactMap { AuthProvider(rawValue: $0) }
 
         do {
-            switch provider {
-            case .apple:
-                try await appleAuthService.signOut(uid)
-            case .github:
-                try await githubAuthService.signOut(uid)
-            case .google:
-                try await googleAuthService.signOut(uid)
-            }
+            try await authService.clearCurrentSession()
         } catch {
-            if case AuthError.notAuthenticated = error.toDomain() {
-                try await authService.clearCurrentSession()
-            } else {
-                throw error.toDomain()
-            }
+            throw error.toDomain()
         }
 
+        clearProviderSessions(providers)
         widgetSnapshotUpdater.clear()
     }
 
@@ -114,6 +97,7 @@ final class AuthenticationRepositoryImpl: AuthenticationRepository {
         do {
             try await authService.deleteCurrentUser()
             try await authService.clearCurrentSession()
+            clearProviderSessions(providers)
             widgetSnapshotUpdater.clear()
         } catch {
             throw error.toDomain()
@@ -122,6 +106,19 @@ final class AuthenticationRepositoryImpl: AuthenticationRepository {
 }
 
 private extension AuthenticationRepositoryImpl {
+    func clearProviderSessions(_ providers: [AuthProvider]) {
+        for provider in providers {
+            switch provider {
+            case .apple:
+                appleAuthService.clearLocalSession()
+            case .github:
+                githubAuthService.clearLocalSession()
+            case .google:
+                googleAuthService.clearLocalSession()
+            }
+        }
+    }
+
     func mapSignInError(_ error: Error) -> Error {
         if let emailError = error as? EmailError,
            emailError == .notFound {

Application/Data/Tests/Repository/AuthenticationRepositoryImplTests.swift

@@ -44,34 +44,68 @@ struct AuthenticationRepositoryImplTests {
         ])
     }
 
-    @Test("Apple 로그아웃은 provider 로그아웃 뒤 위젯 데이터를 정리한다")
-    func Apple_로그아웃은_provider_로그아웃_뒤_위젯_데이터를_정리한다() async throws {
+    @Test("로그아웃은 공통 세션 정리 후 연결된 모든 provider 세션과 위젯 데이터를 정리한다")
+    func 로그아웃은_공통_세션_정리_후_연결된_모든_provider_세션과_위젯_데이터를_정리한다() async throws {
         let fixture = makeAuthenticationRepositoryFixture(
             uid: "user-id",
-            providerID: "apple.com"
+            providerIDs: ["apple.com", "github.com", "google.com"]
+        )
+
+        try await fixture.repository.signOut()
+
+        #expect(fixture.events.values() == [
+            "auth.clearCurrentSession",
+            "apple.clearLocalSession",
+            "github.clearLocalSession",
+            "google.clearLocalSession",
+            "widget.clear"
+        ])
+    }
+
+    @Test("공통 세션 정리 실패는 provider 세션과 위젯 데이터를 정리하지 않고 오류를 전달한다")
+    func 공통_세션_정리_실패는_provider_세션과_위젯_데이터를_정리하지_않고_오류를_전달한다() async {
+        let fixture = makeAuthenticationRepositoryFixture(
+            uid: "user-id",
+            providerIDs: ["apple.com", "github.com", "google.com"],
+            clearCurrentSessionError: AuthenticationRepositoryTestError.clearCurrentSession
         )
 
+        await #expect(throws: AuthenticationRepositoryTestError.clearCurrentSession) {
+            try await fixture.repository.signOut()
+        }
+        #expect(fixture.events.values() == ["auth.clearCurrentSession"])
+    }
+
+    @Test("provider 목록이 없어도 공통 세션과 위젯 데이터를 정리한다")
+    func provider_목록이_없어도_공통_세션과_위젯_데이터를_정리한다() async throws {
+        let fixture = makeAuthenticationRepositoryFixture(uid: "user-id")
+
         try await fixture.repository.signOut()
 
         #expect(fixture.events.values() == [
-            "apple.signOut",
+            "auth.clearCurrentSession",
             "widget.clear"
         ])
     }
 
-    @Test("Apple 회원탈퇴는 grant 정리 후 사용자와 세션과 위젯 데이터를 정리한다")
-    func Apple_회원탈퇴는_grant_정리_후_사용자와_세션과_위젯_데이터를_정리한다() async throws {
+    @Test("회원탈퇴는 provider grant 정리 후 사용자와 로컬 세션과 위젯 데이터를 정리한다")
+    func 회원탈퇴는_provider_grant_정리_후_사용자와_로컬_세션과_위젯_데이터를_정리한다() async throws {
         let fixture = makeAuthenticationRepositoryFixture(
             uid: "user-id",
-            providerIDs: ["apple.com"]
+            providerIDs: ["apple.com", "github.com", "google.com"]
         )
 
         try await fixture.repository.delete()
 
         #expect(fixture.events.values() == [
             "apple.deleteAuth",
+            "github.deleteAuth",
+            "google.deleteAuth",
             "auth.deleteCurrentUser",
             "auth.clearCurrentSession",
+            "apple.clearLocalSession",
+            "github.clearLocalSession",
+            "google.clearLocalSession",
             "widget.clear"
         ])
     }
@@ -98,14 +132,16 @@ struct AuthenticationRepositoryImplTests {
         providerID: String? = nil,
         providerIDs: [String] = [],
         signInResult: Result<AuthDataResponse?, Error> = .success(nil),
-        deleteCurrentUserError: Error? = nil
+        deleteCurrentUserError: Error? = nil,
+        clearCurrentSessionError: Error? = nil
     ) -> AuthenticationRepositoryFixture {
         let events = AuthenticationRepositoryEventRecorder()
         let authService = AuthenticationRepositoryAuthServiceSpy(
             uid: uid,
             providerID: providerID,
             providerIDs: providerIDs,
             deleteCurrentUserError: deleteCurrentUserError,
+            clearCurrentSessionError: clearCurrentSessionError,
             events: events
         )
         let appleAuthService = AuthenticationServiceSpy(
@@ -149,6 +185,7 @@ private struct AuthenticationRepositoryFixture {
 }
 
 private enum AuthenticationRepositoryTestError: Error, Equatable {
+    case clearCurrentSession
     case requiresRecentLogin
 }
 
@@ -171,6 +208,7 @@ final class AuthenticationRepositoryAuthServiceSpy: AuthService {
     private let subject: CurrentValueSubject<Bool, Never>
     private let providerID: String?
     private let deleteCurrentUserError: Error?
+    private let clearCurrentSessionError: Error?
     private let events: AuthenticationRepositoryEventRecorder
 
     var uid: String?
@@ -183,13 +221,15 @@ final class AuthenticationRepositoryAuthServiceSpy: AuthService {
         providerIDs: [String],
         providerCount: Int? = nil,
         deleteCurrentUserError: Error? = nil,
+        clearCurrentSessionError: Error? = nil,
         events: AuthenticationRepositoryEventRecorder
     ) {
         self.uid = uid
         self.providerID = providerID
         self.providerIDs = providerIDs
         self.providerCount = providerCount ?? providerIDs.count
         self.deleteCurrentUserError = deleteCurrentUserError
+        self.clearCurrentSessionError = clearCurrentSessionError
         self.events = events
         self.subject = CurrentValueSubject<Bool, Never>(uid != nil)
     }
@@ -223,10 +263,13 @@ final class AuthenticationRepositoryAuthServiceSpy: AuthService {
 
     func clearCurrentSession() async throws {
         events.record("auth.clearCurrentSession")
+        if let clearCurrentSessionError {
+            throw clearCurrentSessionError
+        }
     }
 }
 
-actor AuthenticationServiceSpy: AuthenticationService {
+final class AuthenticationServiceSpy: AuthenticationService {
     private let provider: String
     private let signInResult: Result<AuthDataResponse?, Error>
     private let linkResult: Result<Bool, Error>
@@ -252,8 +295,8 @@ actor AuthenticationServiceSpy: AuthenticationService {
         return try signInResult.get()
     }
 
-    func signOut(_ uid: String) async throws {
-        events.record("\(provider).signOut")
+    func clearLocalSession() {
+        events.record("\(provider).clearLocalSession")
     }
 
     func deleteAuth(_ uid: String) async throws {

Application/Infra/Sources/Common/InfraLayerError.swift

@@ -19,6 +19,10 @@ enum FirestoreError: Error, LocalizedError {
     }
 }
 
+enum UIError: Error {
+    case notFoundTopViewController
+}
+
 enum SocialLoginError: Error {
     case invalidOAuthCallback
     case failedToStartWebAuthenticationSession
@@ -40,7 +44,8 @@ extension Error {
         case let webAuthError as ASWebAuthenticationSessionError:
             return webAuthError.code == .canceledLogin
         default:
-            return false
+            let error = self as NSError
+            return error.domain == "com.google.GIDSignIn" && error.code == -5
         }
     }
 }

Application/Infra/Sources/Common/TopViewControllerProvider.swift

@@ -0,0 +1,65 @@
+//
+//  TopViewControllerProvider.swift
+//  Infra
+//
+//  Created by opfic on 7/26/26.
+//
+
+import UIKit
+
+enum TopViewControllerProvider {
+    struct Candidate {
+        let identifier: String
+        let rootViewController: UIViewController?
+    }
+
+    @MainActor
+    static func topViewController(identifier: String) -> UIViewController? {
+        let candidates = UIApplication.shared.connectedScenes
+            .compactMap { $0 as? UIWindowScene }
+            .map {
+                Candidate(
+                    identifier: $0.session.persistentIdentifier,
+                    rootViewController: $0.windows
+                        .first(where: \.isKeyWindow)?
+                        .rootViewController
+                )
+            }
+
+        return topViewController(
+            identifier: identifier,
+            candidates: candidates
+        )
+    }
+
+    @MainActor
+    static func topViewController(
+        identifier: String,
+        candidates: [Candidate]
+    ) -> UIViewController? {
+        let rootViewController = candidates
+            .first {
+                $0.identifier == identifier
+            }?
+            .rootViewController
+        return topViewController(from: rootViewController)
+    }
+
+    @MainActor
+    static func topViewController(from viewController: UIViewController?) -> UIViewController? {
+        if let navigationController = viewController as? UINavigationController {
+            return topViewController(from: navigationController.visibleViewController)
+        }
+
+        if let tabBarController = viewController as? UITabBarController,
+           let selectedViewController = tabBarController.selectedViewController {
+            return topViewController(from: selectedViewController)
+        }
+
+        if let presentedViewController = viewController?.presentedViewController {
+            return topViewController(from: presentedViewController)
+        }
+
+        return viewController
+    }
+}

Application/Infra/Sources/Service/AuthServiceImpl.swift

@@ -119,6 +119,11 @@ final class AuthServiceImpl: AuthService {
     func clearCurrentSession() async throws {
         logger.info("Clearing current auth session")
 
+        if let uid {
+            let infoRef = store.document(FirestorePath.userData(uid, document: .tokens))
+            try? await infoRef.updateData(["fcmToken": FieldValue.delete()])
+        }
+
         do {
             if messaging.fcmToken != nil {
                 try await messaging.deleteToken()

Application/Infra/Sources/Service/FunctionAPIClient.swift

@@ -112,6 +112,10 @@ struct OAuthAuthenticationTicketRequest: Encodable {
     let appVerifier: String
 }
 
+struct GoogleAuthorizationCodeRequest: Encodable {
+    let serverAuthCode: String
+}
+
 struct AppleChallengeResponse: Decodable {
     let challengeId: String
     let hashedNonce: String