diff --git a/Application/DevLogCore/Sources/ActivityKind.swift b/Application/DevLogCore/Sources/ActivityKind.swift
index 27e939b1..823cec07 100644
--- a/Application/DevLogCore/Sources/ActivityKind.swift
+++ b/Application/DevLogCore/Sources/ActivityKind.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-public enum ActivityKind: String, Hashable, Sendable {
+public enum ActivityKind: String, Hashable {
     case created
     case completed
     case deleted
diff --git a/Application/DevLogCore/Sources/Logger.swift b/Application/DevLogCore/Sources/Logger.swift
index b34e192a..553677c2 100644
--- a/Application/DevLogCore/Sources/Logger.swift
+++ b/Application/DevLogCore/Sources/Logger.swift
@@ -8,7 +8,7 @@
 import Foundation
 import os.log
 
-public final class Logger: Sendable {
+public final class Logger {
     private let subsystem: String
     private let category: String
     private let osLog: OSLog
diff --git a/Application/DevLogCore/Sources/TodayDisplayOptions.swift b/Application/DevLogCore/Sources/TodayDisplayOptions.swift
index ed063c6a..a27ceb39 100644
--- a/Application/DevLogCore/Sources/TodayDisplayOptions.swift
+++ b/Application/DevLogCore/Sources/TodayDisplayOptions.swift
@@ -7,14 +7,14 @@
 
 import Foundation
 
-public struct TodayDisplayOptions: Equatable, Sendable {
-    public enum DueDateVisibility: String, CaseIterable, Equatable, Sendable {
+public struct TodayDisplayOptions: Equatable {
+    public enum DueDateVisibility: String, CaseIterable, Equatable {
         case all
         case withDueDateOnly
         case withoutDueDateOnly
     }
 
-    public enum FocusVisibility: String, CaseIterable, Equatable, Sendable {
+    public enum FocusVisibility: String, CaseIterable, Equatable {
         case all
         case focusedOnly
     }
diff --git a/Application/DevLogCore/Sources/WidgetTodoSnapshot.swift b/Application/DevLogCore/Sources/WidgetTodoSnapshot.swift
index 200e1188..a1b08f27 100644
--- a/Application/DevLogCore/Sources/WidgetTodoSnapshot.swift
+++ b/Application/DevLogCore/Sources/WidgetTodoSnapshot.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-public struct WidgetTodoSnapshot: Equatable, Sendable {
+public struct WidgetTodoSnapshot: Equatable {
     public let id: String
     public let number: Int?
     public let title: String
diff --git a/Application/DevLogData/Sources/Protocol/AuthService.swift b/Application/DevLogData/Sources/Protocol/AuthService.swift
index f8b1cacf..f6c667b0 100644
--- a/Application/DevLogData/Sources/Protocol/AuthService.swift
+++ b/Application/DevLogData/Sources/Protocol/AuthService.swift
@@ -8,7 +8,7 @@
 import Combine
 import Foundation
 
-public protocol AuthService: Sendable {
+public protocol AuthService {
     var uid: String? { get }
     var providerIDs: [String] { get }
     var currentUserEmail: String? { get }
diff --git a/Application/DevLogData/Sources/Protocol/AuthenticationService.swift b/Application/DevLogData/Sources/Protocol/AuthenticationService.swift
index 6a9a23b1..c2c783b8 100644
--- a/Application/DevLogData/Sources/Protocol/AuthenticationService.swift
+++ b/Application/DevLogData/Sources/Protocol/AuthenticationService.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-public protocol AuthenticationService: Sendable {
+public protocol AuthenticationService {
     func signIn() async throws -> AuthDataResponse
     func signOut(_ uid: String) async throws
     func deleteAuth(_ uid: String) async throws
diff --git a/Application/DevLogData/Sources/Protocol/UserService.swift b/Application/DevLogData/Sources/Protocol/UserService.swift
index 67174c5d..3a82c536 100644
--- a/Application/DevLogData/Sources/Protocol/UserService.swift
+++ b/Application/DevLogData/Sources/Protocol/UserService.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-public protocol UserService: Sendable {
+public protocol UserService {
     func upsertUser(_ response: AuthDataResponse) async throws
     func fetchUserProfile() async throws -> UserProfileResponse
     func upsertStatusMessage(_ message: String) async throws
diff --git a/Application/DevLogData/Sources/Protocol/WebPageImageStore.swift b/Application/DevLogData/Sources/Protocol/WebPageImageStore.swift
index 198152b6..6a2bb78f 100644
--- a/Application/DevLogData/Sources/Protocol/WebPageImageStore.swift
+++ b/Application/DevLogData/Sources/Protocol/WebPageImageStore.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-public protocol WebPageImageStore: Sendable {
+public protocol WebPageImageStore {
     func cachedImageURL(for url: URL) async throws -> URL
     func saveImage(_ data: Data, for url: URL) async throws -> URL
     func dirSizeInBytes() async -> Int64
diff --git a/Application/DevLogData/Sources/Protocol/WidgetSnapshotPreferenceStore.swift b/Application/DevLogData/Sources/Protocol/WidgetSnapshotPreferenceStore.swift
index 8c0a4ae2..160957c3 100644
--- a/Application/DevLogData/Sources/Protocol/WidgetSnapshotPreferenceStore.swift
+++ b/Application/DevLogData/Sources/Protocol/WidgetSnapshotPreferenceStore.swift
@@ -8,7 +8,7 @@
 import Foundation
 import DevLogCore
 
-public protocol WidgetSnapshotPreferenceStore: Sendable {
+public protocol WidgetSnapshotPreferenceStore {
     func heatmapActivityTypes() -> [String]
     func setHeatmapActivityTypes(_ activityTypes: [String])
     func selectedActivityKinds() -> Set<ActivityKind>
diff --git a/Application/DevLogData/Sources/Protocol/WidgetSnapshotUpdater.swift b/Application/DevLogData/Sources/Protocol/WidgetSnapshotUpdater.swift
index 3fa25bc7..1748bd34 100644
--- a/Application/DevLogData/Sources/Protocol/WidgetSnapshotUpdater.swift
+++ b/Application/DevLogData/Sources/Protocol/WidgetSnapshotUpdater.swift
@@ -8,7 +8,7 @@
 import Foundation
 import DevLogCore
 
-public protocol WidgetSnapshotUpdater: Sendable {
+public protocol WidgetSnapshotUpdater {
     func updateTodaySnapshot(
         todos: [WidgetTodoSnapshot],
         now: Date
diff --git a/Application/DevLogDomain/Sources/Entity/AuthProvider.swift b/Application/DevLogDomain/Sources/Entity/AuthProvider.swift
index d739738b..ae30ca08 100644
--- a/Application/DevLogDomain/Sources/Entity/AuthProvider.swift
+++ b/Application/DevLogDomain/Sources/Entity/AuthProvider.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-public enum AuthProvider: String, CaseIterable {
+public enum AuthProvider: String, CaseIterable, Sendable {
     case apple = "apple.com"
     case google = "google.com"
     case github = "github.com"
diff --git a/Application/DevLogDomain/Sources/Protocol/AuthenticationRepository.swift b/Application/DevLogDomain/Sources/Protocol/AuthenticationRepository.swift
index 9cbd628a..5652583a 100644
--- a/Application/DevLogDomain/Sources/Protocol/AuthenticationRepository.swift
+++ b/Application/DevLogDomain/Sources/Protocol/AuthenticationRepository.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-public protocol AuthenticationRepository: Sendable {
+public protocol AuthenticationRepository {
     func signIn(_ provider: AuthProvider) async throws
     func signOut() async throws
     func restore() -> Bool
diff --git a/Application/DevLogDomain/Sources/UseCase/Auth/SignIn/SignInUseCase.swift b/Application/DevLogDomain/Sources/UseCase/Auth/SignIn/SignInUseCase.swift
index 926e656e..46122e3c 100644
--- a/Application/DevLogDomain/Sources/UseCase/Auth/SignIn/SignInUseCase.swift
+++ b/Application/DevLogDomain/Sources/UseCase/Auth/SignIn/SignInUseCase.swift
@@ -5,6 +5,6 @@
 //  Created by 최윤진 on 11/2/25.
 //
 
-public protocol SignInUseCase: Sendable {
+public protocol SignInUseCase {
     func execute(_ provider: AuthProvider) async throws
 }
diff --git a/Application/DevLogInfra/Sources/Common/FirebaseDependency.swift b/Application/DevLogInfra/Sources/Common/FirebaseDependency.swift
index 25013ca1..d34077da 100644
--- a/Application/DevLogInfra/Sources/Common/FirebaseDependency.swift
+++ b/Application/DevLogInfra/Sources/Common/FirebaseDependency.swift
@@ -10,7 +10,7 @@ import FirebaseFirestore
 import FirebaseFunctions
 import FirebaseMessaging
 
-struct FirebaseDependency<Value>: @unchecked Sendable {
+struct FirebaseDependency<Value> {
     private let value: Value
 
     init(value: Value) {
diff --git a/Application/DevLogInfra/Sources/Common/TopViewControllerProvider.swift b/Application/DevLogInfra/Sources/Common/TopViewControllerProvider.swift
index 95ae7423..e6d8ee41 100644
--- a/Application/DevLogInfra/Sources/Common/TopViewControllerProvider.swift
+++ b/Application/DevLogInfra/Sources/Common/TopViewControllerProvider.swift
@@ -8,7 +8,7 @@
 import UIKit
 import DevLogData
 
-final class TopViewControllerProvider: Sendable {
+final class TopViewControllerProvider {
     @MainActor
     func topViewController() -> UIViewController? {
         guard let keyWindow = keyWindow() else {
diff --git a/Application/DevLogInfra/Sources/Service/AuthServiceImpl.swift b/Application/DevLogInfra/Sources/Service/AuthServiceImpl.swift
index 00836e3e..c5587dc2 100644
--- a/Application/DevLogInfra/Sources/Service/AuthServiceImpl.swift
+++ b/Application/DevLogInfra/Sources/Service/AuthServiceImpl.swift
@@ -114,7 +114,7 @@ final class AuthServiceImpl: AuthService {
 
 }
 
-private final class AuthStatePublisher: @unchecked Sendable {
+private final class AuthStatePublisher {
     private let logger: Logger
     private let subject: CurrentValueSubject<Bool, Never>
     private let lock = NSLock()
diff --git a/Application/DevLogInfra/Sources/Service/SocialLogin/AppleAuthenticationServiceImpl.swift b/Application/DevLogInfra/Sources/Service/SocialLogin/AppleAuthenticationServiceImpl.swift
index e95d640d..ab354471 100644
--- a/Application/DevLogInfra/Sources/Service/SocialLogin/AppleAuthenticationServiceImpl.swift
+++ b/Application/DevLogInfra/Sources/Service/SocialLogin/AppleAuthenticationServiceImpl.swift
@@ -300,7 +300,7 @@ final class AppleAuthenticationServiceImpl: AuthenticationService {
     }
 }
 
-private final class AppleSignInSession: @unchecked Sendable {
+private final class AppleSignInSession {
     @MainActor
     private var delegate: AppleSignInDelegate?
     @MainActor
diff --git a/Application/DevLogPersistence/Sources/Widget/UserDefaultsDependency.swift b/Application/DevLogPersistence/Sources/Widget/UserDefaultsDependency.swift
index b1526771..e74cae86 100644
--- a/Application/DevLogPersistence/Sources/Widget/UserDefaultsDependency.swift
+++ b/Application/DevLogPersistence/Sources/Widget/UserDefaultsDependency.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-struct UserDefaultsDependency: @unchecked Sendable {
+struct UserDefaultsDependency {
     private let value: UserDefaults
 
     init(value: UserDefaults) {
diff --git a/Application/DevLogPresentation/Sources/Login/LoginFeature.swift b/Application/DevLogPresentation/Sources/Login/LoginFeature.swift
index 4d0fcde8..476ed292 100644
--- a/Application/DevLogPresentation/Sources/Login/LoginFeature.swift
+++ b/Application/DevLogPresentation/Sources/Login/LoginFeature.swift
@@ -6,7 +6,7 @@
 //
 
 import ComposableArchitecture
-import DevLogDomain
+@preconcurrency import DevLogDomain
 import Foundation
 
 @Reducer
@@ -20,7 +20,7 @@ struct LoginFeature {
         var alertMessage = ""
     }
 
-    enum Action {
+    enum Action: Sendable {
         case setAlert(Bool, AlertType? = nil)
         case tapSignInButton(AuthProvider)
         case signInSucceeded
@@ -28,12 +28,12 @@ struct LoginFeature {
         case signInCancelled
     }
 
-    enum AlertType: Equatable {
+    enum AlertType: Equatable, Sendable {
         case emailUnavailable
         case error
     }
 
-    @Dependency(\.signInUseCase) var signInUseCase
+    @Dependency(SignInUseCaseDependency.self) var signInUseCase
 
     var body: some ReducerOf<Self> {
         Reduce { state, action in
diff --git a/Widget/DevLogWidgetCore/Sources/Common/UserDefaultsDependency.swift b/Widget/DevLogWidgetCore/Sources/Common/UserDefaultsDependency.swift
index 9de0492b..76b83f1d 100644
--- a/Widget/DevLogWidgetCore/Sources/Common/UserDefaultsDependency.swift
+++ b/Widget/DevLogWidgetCore/Sources/Common/UserDefaultsDependency.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-struct UserDefaultsDependency: @unchecked Sendable {
+struct UserDefaultsDependency {
     private let value: UserDefaults
 
     init(value: UserDefaults) {
diff --git a/Widget/DevLogWidgetCore/Sources/Common/WidgetSharedDefaultsStore.swift b/Widget/DevLogWidgetCore/Sources/Common/WidgetSharedDefaultsStore.swift
index 89f20d74..9d1ee58d 100644
--- a/Widget/DevLogWidgetCore/Sources/Common/WidgetSharedDefaultsStore.swift
+++ b/Widget/DevLogWidgetCore/Sources/Common/WidgetSharedDefaultsStore.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-public final class WidgetSharedDefaultsStore: Sendable {
+public final class WidgetSharedDefaultsStore {
     private let userDefaults: UserDefaultsDependency
 
     public init(userDefaults: UserDefaults = UserDefaults(suiteName: WidgetAppGroup.identifier) ?? .standard) {
diff --git a/Widget/DevLogWidgetCore/Sources/Common/WidgetSnapshotStore.swift b/Widget/DevLogWidgetCore/Sources/Common/WidgetSnapshotStore.swift
index 9801befd..727e2bc8 100644
--- a/Widget/DevLogWidgetCore/Sources/Common/WidgetSnapshotStore.swift
+++ b/Widget/DevLogWidgetCore/Sources/Common/WidgetSnapshotStore.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-public final class WidgetSnapshotStore: Sendable {
+public final class WidgetSnapshotStore {
     private let store: WidgetSharedDefaultsStore
     private let encoder = JSONEncoder()
     private let decoder = JSONDecoder()
diff --git a/Widget/DevLogWidgetCore/Sources/Heatmap/HeatmapWidgetSnapshotFactory.swift b/Widget/DevLogWidgetCore/Sources/Heatmap/HeatmapWidgetSnapshotFactory.swift
index eda3c1e1..5db55edf 100644
--- a/Widget/DevLogWidgetCore/Sources/Heatmap/HeatmapWidgetSnapshotFactory.swift
+++ b/Widget/DevLogWidgetCore/Sources/Heatmap/HeatmapWidgetSnapshotFactory.swift
@@ -8,8 +8,8 @@
 import Foundation
 import DevLogCore
 
-public struct HeatmapWidgetSnapshotFactory: Sendable {
-    fileprivate struct DailyCounts: Sendable {
+public struct HeatmapWidgetSnapshotFactory {
+    fileprivate struct DailyCounts {
         var createdCount = 0
         var completedCount = 0
         var deletedCount = 0
diff --git a/Widget/DevLogWidgetCore/Sources/Today/TodayWidgetSnapshotFactory.swift b/Widget/DevLogWidgetCore/Sources/Today/TodayWidgetSnapshotFactory.swift
index 351543f8..efa0a212 100644
--- a/Widget/DevLogWidgetCore/Sources/Today/TodayWidgetSnapshotFactory.swift
+++ b/Widget/DevLogWidgetCore/Sources/Today/TodayWidgetSnapshotFactory.swift
@@ -8,8 +8,8 @@
 import Foundation
 import DevLogCore
 
-public struct TodayWidgetSnapshotFactory: Sendable {
-    private enum SectionCategory: String, CaseIterable, Sendable {
+public struct TodayWidgetSnapshotFactory {
+    private enum SectionCategory: String, CaseIterable {
         case focused
         case overdue
         case dueSoon
@@ -17,7 +17,7 @@ public struct TodayWidgetSnapshotFactory: Sendable {
         case unscheduled
     }
 
-    private struct SectionCollection: Sendable {
+    private struct SectionCollection {
         var focused = [TodayWidgetTodoItem]()
         var overdue = [TodayWidgetTodoItem]()
         var dueSoon = [TodayWidgetTodoItem]()
@@ -40,7 +40,7 @@ public struct TodayWidgetSnapshotFactory: Sendable {
         }
     }
 
-    private struct TodayWidgetTodoItem: Sendable {
+    private struct TodayWidgetTodoItem {
         let id: String
         let number: Int
         let title: String