diff --git a/DevLog/Presentation/ViewModel/AccountViewModel.swift b/DevLog/Presentation/ViewModel/AccountViewModel.swift
index 9aac266..096d3f0 100644
--- a/DevLog/Presentation/ViewModel/AccountViewModel.swift
+++ b/DevLog/Presentation/ViewModel/AccountViewModel.swift
@@ -64,14 +64,15 @@ final class AccountViewModel: Store {
 
     func reduce(with action: Action) -> [SideEffect] {
         var state = self.state
+        var effects: [SideEffect] = []
 
         switch action {
         case .onAppear:
-            return [.fetch]
+            effects = [.fetch]
         case .linkWithProvider(let value):
-            return [.link(value)]
+            effects = [.link(value)]
         case .unlinkFromProvider(let value):
-            return [.unlink(value)]
+            effects = [.unlink(value)]
         case .setAlert(let isPresented, let type):
             setAlert(&state, isPresented: isPresented, type: type)
         case .setToast(let isPresented, let type):
@@ -86,7 +87,7 @@ final class AccountViewModel: Store {
         }
 
         self.state = state
-        return []
+        return effects
     }
 
     func run(_ effect: SideEffect) {
diff --git a/DevLog/Presentation/ViewModel/LoginViewModel.swift b/DevLog/Presentation/ViewModel/LoginViewModel.swift
index 45cdb56..622d3e0 100644
--- a/DevLog/Presentation/ViewModel/LoginViewModel.swift
+++ b/DevLog/Presentation/ViewModel/LoginViewModel.swift
@@ -60,16 +60,15 @@ final class LoginViewModel: Store {
 
     func reduce(with action: Action) -> [SideEffect] {
         var state = self.state
+        var effects: [SideEffect] = []
         
         switch action {
         case .setAlert(let isPresented):
             setAlert(&state, isPresented: isPresented)
         case .tapSignInButton(let authProvider):
-            self.state = state
-            return [.signIn(authProvider)]
+            effects = [.signIn(authProvider)]
         case .tapSignOutButton, .signOutAuto:
-            self.state = state
-            return [.signOut]
+            effects = [.signOut]
         case .setLoading(let value):
             state.isLoading = value
         case .setLogined(let result):
@@ -77,7 +76,7 @@ final class LoginViewModel: Store {
         }
         
         self.state = state
-        return []
+        return effects
     }
 
     func run(_ effect: SideEffect) {
diff --git a/DevLog/Presentation/ViewModel/PushNotificationSettingsViewModel.swift b/DevLog/Presentation/ViewModel/PushNotificationSettingsViewModel.swift
index 9979086..e782912 100644
--- a/DevLog/Presentation/ViewModel/PushNotificationSettingsViewModel.swift
+++ b/DevLog/Presentation/ViewModel/PushNotificationSettingsViewModel.swift
@@ -61,6 +61,7 @@ final class PushNotificationSettingsViewModel: Store {
     func reduce(with action: Action) -> [SideEffect] {
         var state = self.state
         var effects: [SideEffect] = []
+
         switch action {
         case .fetchSettings:
             effects = [.fetchPushNotificationSettings]
diff --git a/DevLog/Presentation/ViewModel/RootViewModel.swift b/DevLog/Presentation/ViewModel/RootViewModel.swift
index 0ff64a0..1cd8c4c 100644
--- a/DevLog/Presentation/ViewModel/RootViewModel.swift
+++ b/DevLog/Presentation/ViewModel/RootViewModel.swift
@@ -66,6 +66,7 @@ final class RootViewModel: Store {
     
     func reduce(with action: Action) -> [SideEffect] {
         var state = self.state
+        var effects: [SideEffect] = []
         
         switch action {
         case .setAlert(let isPresented):
@@ -82,13 +83,13 @@ final class RootViewModel: Store {
         case .setTheme(let theme):
             state.theme = theme
         case .signOutAuto:
-            return [.signOut]
+            effects = [.signOut]
         case .didLogined(let result):
             state.signIn = result
         }
         
         self.state = state
-        return []
+        return effects
     }
     
     func run(_ effect: SideEffect) {
diff --git a/DevLog/Presentation/ViewModel/SettingViewModel.swift b/DevLog/Presentation/ViewModel/SettingViewModel.swift
index 7a68862..80a9604 100644
--- a/DevLog/Presentation/ViewModel/SettingViewModel.swift
+++ b/DevLog/Presentation/ViewModel/SettingViewModel.swift
@@ -65,6 +65,9 @@ final class SettingViewModel: Store {
     }
 
     func reduce(with action: Action) -> [SideEffect] {
+        var state = self.state
+        var effects: [SideEffect] = []
+
         switch action {
         case .setAlert(let isPresented, let type):
             setAlert(&state, isPresented: isPresented, type: type)
@@ -76,9 +79,9 @@ final class SettingViewModel: Store {
         case .updateDirSize:
             state.dirSize = dirSizeInBytes()
         case .tapDeleteAuthButton:
-            return [.deleteAuth]
+            effects = [.deleteAuth]
         case .tapSignOutButton:
-            return [.signOut]
+            effects = [.signOut]
         case .tapRemoveCacheButton:
             setAlert(&state, isPresented: true, type: .removeCache)
         case .confirmRemoveCache:
@@ -90,7 +93,9 @@ final class SettingViewModel: Store {
                 setAlert(&state, isPresented: true, type: .error)
             }
         }
-        return []
+
+        self.state = state
+        return effects
     }
 
     func run(_ effect: SideEffect) {
diff --git a/DevLog/Presentation/ViewModel/TodoDetailViewModel.swift b/DevLog/Presentation/ViewModel/TodoDetailViewModel.swift
index 8f484b2..850fba7 100644
--- a/DevLog/Presentation/ViewModel/TodoDetailViewModel.swift
+++ b/DevLog/Presentation/ViewModel/TodoDetailViewModel.swift
@@ -62,7 +62,7 @@ final class TodoDetailViewModel: Store {
         case .setLoading(let value):
             state.isLoading = value
         case .upsertTodo(let todo):
-            return [.upsertTodo(todo)]
+            effects = [.upsertTodo(todo)]
         }
 
         self.state = state
diff --git a/DevLog/Presentation/ViewModel/TodoEditorViewModel.swift b/DevLog/Presentation/ViewModel/TodoEditorViewModel.swift
index 8942b76..f5c0ae5 100644
--- a/DevLog/Presentation/ViewModel/TodoEditorViewModel.swift
+++ b/DevLog/Presentation/ViewModel/TodoEditorViewModel.swift
@@ -78,15 +78,19 @@ final class TodoEditorViewModel: Store {
     }
 
     func reduce(with action: Action) -> [SideEffect] {
+        var state = self.state
+
         switch action {
         case .addTag(let tag):
-            if !tag.isEmpty { state.tags.append(tag) }
+            if !tag.isEmpty {
+                state.tags.append(tag)
+            }
         case .removeTag(let tagText):
             state.tags.removeAll { $0 == tagText }
         case .setContent(let stringValue),
              .setTagText(let stringValue),
              .setTitle(let stringValue):
-            handleStringAction(action, stringValue: stringValue)
+            handleStringAction(action, stringValue: stringValue, state: &state)
         case .setDueDate(let dueDate):
             if let tomorrowDate = calendar.date(byAdding: .day, value: 1, to: Date()), let dueDate {
                 state.dueDate = max(dueDate, tomorrowDate)
@@ -102,12 +106,18 @@ final class TodoEditorViewModel: Store {
                 state.dueDate = calendar.date(byAdding: .day, value: 1, to: Date())
             }
         }
+
+        self.state = state
         return []
     }
 }
 
 extension TodoEditorViewModel {
-    private func handleStringAction(_ action: Action, stringValue: String) {
+    private func handleStringAction(
+        _ action: Action,
+        stringValue: String,
+        state: inout State
+    ) {
         switch action {
         case .setContent:
             state.content = stringValue
diff --git a/DevLog/Presentation/ViewModel/TodoManageViewModel.swift b/DevLog/Presentation/ViewModel/TodoManageViewModel.swift
index ac993b6..bf3549c 100644
--- a/DevLog/Presentation/ViewModel/TodoManageViewModel.swift
+++ b/DevLog/Presentation/ViewModel/TodoManageViewModel.swift
@@ -26,6 +26,8 @@ final class TodoManageViewModel: Store {
     }
 
     func reduce(with action: Action) -> [SideEffect] {
+        var state = self.state
+
         switch action {
         case .moveItem(let from, let target):
             state.todoKindPreferences.move(fromOffsets: from, toOffset: target)
@@ -34,6 +36,8 @@ final class TodoManageViewModel: Store {
                 state.todoKindPreferences[index].isVisible.toggle()
             }
         }
+
+        self.state = state
         return []
     }
 }