diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5a13eaba..9b410321 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,7 +11,7 @@ jobs:
   ci:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
       - uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6.0.0
         with:
           node-version: 24.11.1
diff --git a/.github/workflows/create-release-pull-request.yml b/.github/workflows/create-release-pull-request.yml
index 14566aed..4b563dd7 100644
--- a/.github/workflows/create-release-pull-request.yml
+++ b/.github/workflows/create-release-pull-request.yml
@@ -12,7 +12,7 @@ jobs:
       pull-requests: write
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
       - uses: ruby/setup-ruby@d5126b9b3579e429dd52e51e68624dda2e05be25 # v1.267.0
         with:
           ruby-version: 3.4.7
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 899246bc..e1d34767 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -12,7 +12,7 @@ jobs:
     if: github.event.pull_request.merged == true
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
       - name: Install jq
         run: sudo apt-get install -y jq
       - name: Get version from manifest.json
@@ -31,7 +31,7 @@ jobs:
     needs: create_tag_and_release_note
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
       - uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6.0.0
         with:
           node-version: 24.11.1
diff --git a/.github/workflows/validate-release.yml b/.github/workflows/validate-release.yml
index 27985893..a110b069 100644
--- a/.github/workflows/validate-release.yml
+++ b/.github/workflows/validate-release.yml
@@ -9,7 +9,7 @@ jobs:
   check_manifest_version_update:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
       - name: Install jq
         run: sudo apt-get install jq
       - name: Get latest tag from main branch
diff --git a/src/platform/repository/TabGroupRepository.ts b/src/platform/repository/TabGroupRepository.ts
index b32fa4d4..d45bc3b8 100644
--- a/src/platform/repository/TabGroupRepository.ts
+++ b/src/platform/repository/TabGroupRepository.ts
@@ -4,8 +4,14 @@ import type {
   TabGroup,
   TabGroupColor,
 } from "../../model/TabContainer";
-import type { WindowId } from "../../model/Window";
+import {
+  findGroupsByName,
+  flatTabsInWindows,
+  type Window,
+  type WindowId,
+} from "../../model/Window";
 import { ChromeLocalStorage } from "../storage/ChromeLocalStorage";
+import { addTabsToGroup } from "./TabsRepository";
 
 export const collapseTabGroup = async (groupId: number): Promise<void> => {
   await chrome.tabGroups.update(groupId, { collapsed: true });
@@ -31,6 +37,24 @@ export const createGroupWithTabs = async (name: string, tabIds: number[]) => {
   await chrome.tabGroups.update(groupId, { title: name });
 };
 
+export const groupTabsBySearchKeyword = async (
+  keyword: string,
+  windows: Window[],
+  tabIds: number[],
+) => {
+  const pinnedTabs = flatTabsInWindows(windows).filter((tab) => tab.pinned);
+  const tabIdsExcludingPinned = tabIds.filter(
+    (tabId) => !pinnedTabs.some((tab) => tab.id === tabId),
+  );
+
+  const sameNameGroups = findGroupsByName(keyword, windows);
+  if (sameNameGroups.length > 0) {
+    await addTabsToGroup(tabIdsExcludingPinned, sameNameGroups[0].id);
+  }
+
+  await createGroupWithTabs(keyword, tabIdsExcludingPinned);
+};
+
 export const moveTabGroup = async (
   groupId: number,
   currentWindowId: number,
diff --git a/src/platform/repository/TabsRepository.ts b/src/platform/repository/TabsRepository.ts
index 98793931..c57cf1fa 100644
--- a/src/platform/repository/TabsRepository.ts
+++ b/src/platform/repository/TabsRepository.ts
@@ -1,5 +1,14 @@
-import type { Tab, TabId, TabStatus } from "../../model/Tab";
-import type { WindowId } from "../../model/Window";
+import {
+  isSamePageTabs,
+  type Tab,
+  type TabId,
+  type TabStatus,
+} from "../../model/Tab";
+import {
+  flatTabsInWindows,
+  type Window,
+  type WindowId,
+} from "../../model/Window";
 import { ChromeLocalStorage } from "../storage/ChromeLocalStorage";
 import { ChromeSessionStorage } from "../storage/ChromeSessionStorage";
 
@@ -24,6 +33,31 @@ export const closeTabs = async (tabIds: number[]) => {
   await chrome.tabs.remove(tabIds);
 };
 
+export const moveTabFromRootToPinned = async (
+  tabId: number,
+  windowId: number,
+  index: number,
+) => {
+  await moveTab(tabId, windowId, -1);
+  await pinTab(tabId);
+  await moveTab(tabId, windowId, index);
+};
+
+export const moveTabFromPinnedToPinned = async (
+  tabId: number,
+  sourceWindowId: number,
+  destWindowId: number,
+  index: number,
+) => {
+  if (sourceWindowId === destWindowId) {
+    await moveTab(tabId, sourceWindowId, index);
+  } else {
+    await moveTab(tabId, destWindowId, -1);
+    await pinTab(tabId);
+    await moveTab(tabId, destWindowId, index);
+  }
+};
+
 export const updateTabLastActivatedAt = async (
   tabId: number,
   options?: {
@@ -164,6 +198,18 @@ export const unpinAllTabs = async (tabs: Tab[]) => {
   }
 };
 
+export const resolveDuplicatedTabs = async (
+  windows: Window[],
+  targetTab: Tab,
+) => {
+  const allTabs = flatTabsInWindows(windows);
+  const duplicateTabs = allTabs.filter(
+    (tab) => tab.id !== targetTab.id && isSamePageTabs(tab, targetTab),
+  );
+  const duplicateTabIds = duplicateTabs.map((t) => t.id);
+  await closeTabs(duplicateTabIds);
+};
+
 export const getRecentActiveTabs = async (): Promise<Tab[]> => {
   const recentActiveTabs = await ChromeSessionStorage.getRecentActiveTabs();
   if (!recentActiveTabs) return [];
diff --git a/src/platform/repository/WindowsRepository.ts b/src/platform/repository/WindowsRepository.ts
index eff871bf..9515dcac 100644
--- a/src/platform/repository/WindowsRepository.ts
+++ b/src/platform/repository/WindowsRepository.ts
@@ -129,6 +129,29 @@ export const closeWindow = async (window: Window): Promise<Window[]> => {
   return getWindows();
 };
 
+export const mergeWindow = async (
+  destWindowId: number,
+  sourceWindow: Window,
+) => {
+  for (const child of sourceWindow.children) {
+    if (isPinned(child)) {
+      for (const tab of child.children) {
+        await chrome.tabs.move(tab.id, { windowId: destWindowId, index: -1 });
+        await chrome.tabs.update(tab.id, { pinned: true });
+      }
+    }
+    if (isTabGroup(child)) {
+      await chrome.tabGroups.move(child.id, {
+        windowId: destWindowId,
+        index: -1,
+      });
+    }
+    if (isTab(child)) {
+      await chrome.tabs.move(child.id, { windowId: destWindowId, index: -1 });
+    }
+  }
+};
+
 const applyLastActivatedAtToTabs = async (
   windows: Window[],
 ): Promise<Window[]> => {
diff --git a/src/ui/components/ActionMenu.tsx b/src/ui/components/ActionMenu.tsx
index 017912d9..6d373b43 100644
--- a/src/ui/components/ActionMenu.tsx
+++ b/src/ui/components/ActionMenu.tsx
@@ -59,12 +59,12 @@ import {
 } from "../../platform/repository/TabsRepository";
 import {
   closeWindow,
+  mergeWindow,
   removeStoredWindow,
   restoreWindow,
   saveWindow,
   saveWindows,
 } from "../../platform/repository/WindowsRepository";
-import mergeWindow from "../functions/mergeWindow";
 
 type ActionMenuItemAttrs =
   | {
diff --git a/src/ui/components/DragAndDropContext.tsx b/src/ui/components/DragAndDropContext.tsx
index 0cd74f76..5bec2d27 100644
--- a/src/ui/components/DragAndDropContext.tsx
+++ b/src/ui/components/DragAndDropContext.tsx
@@ -44,6 +44,8 @@ import {
 } from "../../platform/repository/TabGroupRepository";
 import {
   moveTab,
+  moveTabFromPinnedToPinned,
+  moveTabFromRootToPinned,
   moveTabOutOfGroup,
   moveTabToOtherWindow,
   unpinTab,
@@ -53,8 +55,6 @@ import {
   addWindowWithTabGroup,
 } from "../../platform/repository/WindowsRepository";
 import { WindowsContext } from "../contexts/WindowsContext";
-import moveTabFromPinnedToPinned from "../functions/moveTabFromPinnedToPinned";
-import moveTabFromRootToPinned from "../functions/moveTabFromRootToPinned";
 import TabGroupContainer from "./TabGroupContainer";
 import TabItem from "./TabItem";
 
diff --git a/src/ui/components/TabItem.tsx b/src/ui/components/TabItem.tsx
index 682546c2..bf8ce616 100644
--- a/src/ui/components/TabItem.tsx
+++ b/src/ui/components/TabItem.tsx
@@ -28,9 +28,12 @@ import {
   hasDuplicatedTabs,
   type Window,
 } from "../../model/Window";
-import { closeTab, focusTab } from "../../platform/repository/TabsRepository";
+import {
+  closeTab,
+  focusTab,
+  resolveDuplicatedTabs,
+} from "../../platform/repository/TabsRepository";
 import { WindowsContext } from "../contexts/WindowsContext";
-import resolveDuplicatedTabs from "../functions/resolveDuplicatedTabs";
 import { TabItemActionMenu } from "./ActionMenu";
 import TabFavicon from "./TabFavicon";
 
diff --git a/src/ui/functions/groupTabsBySearchKeyword.ts b/src/ui/functions/groupTabsBySearchKeyword.ts
deleted file mode 100644
index e293eaa1..00000000
--- a/src/ui/functions/groupTabsBySearchKeyword.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-import {
-  findGroupsByName,
-  flatTabsInWindows,
-  type Window,
-} from "../../model/Window";
-import { createGroupWithTabs } from "../../platform/repository/TabGroupRepository";
-import { addTabsToGroup } from "../../platform/repository/TabsRepository";
-
-const groupTabsBySearchKeyword = async (
-  keyword: string,
-  windows: Window[],
-  tabIds: number[],
-) => {
-  const pinnedTabs = flatTabsInWindows(windows).filter((tab) => tab.pinned);
-  const tabIdsExcludingPinned = tabIds.filter(
-    (tabId) => !pinnedTabs.some((tab) => tab.id === tabId),
-  );
-
-  const sameNameGroups = findGroupsByName(keyword, windows);
-  if (sameNameGroups.length > 0) {
-    await addTabsToGroup(tabIdsExcludingPinned, sameNameGroups[0].id);
-  }
-
-  await createGroupWithTabs(keyword, tabIdsExcludingPinned);
-};
-
-export default groupTabsBySearchKeyword;
diff --git a/src/ui/functions/mergeWindow.ts b/src/ui/functions/mergeWindow.ts
deleted file mode 100644
index 8ab84a7b..00000000
--- a/src/ui/functions/mergeWindow.ts
+++ /dev/null
@@ -1,23 +0,0 @@
-import { isPinned, isTab, isTabGroup } from "../../model/TabContainer";
-import type { Window } from "../../model/Window";
-import { moveTabGroup } from "../../platform/repository/TabGroupRepository";
-import { moveTab, pinTab } from "../../platform/repository/TabsRepository";
-
-const mergeWindow = async (destWindowId: number, sourceWindow: Window) => {
-  for (const child of sourceWindow.children) {
-    if (isPinned(child)) {
-      for (const tab of child.children) {
-        await moveTab(tab.id, destWindowId, -1);
-        await pinTab(tab.id);
-      }
-    }
-    if (isTabGroup(child)) {
-      await moveTabGroup(child.id, sourceWindow.id, destWindowId, -1);
-    }
-    if (isTab(child)) {
-      await moveTab(child.id, destWindowId, -1);
-    }
-  }
-};
-
-export default mergeWindow;
diff --git a/src/ui/functions/moveTabFromPinnedToPinned.ts b/src/ui/functions/moveTabFromPinnedToPinned.ts
deleted file mode 100644
index cd733cb1..00000000
--- a/src/ui/functions/moveTabFromPinnedToPinned.ts
+++ /dev/null
@@ -1,18 +0,0 @@
-import { moveTab, pinTab } from "../../platform/repository/TabsRepository";
-
-const moveTabFromPinnedToPinned = async (
-  tabId: number,
-  sourceWindowId: number,
-  destWindowId: number,
-  index: number,
-) => {
-  if (sourceWindowId === destWindowId) {
-    await moveTab(tabId, sourceWindowId, index);
-  } else {
-    await moveTab(tabId, destWindowId, -1);
-    await pinTab(tabId);
-    await moveTab(tabId, destWindowId, index);
-  }
-};
-
-export default moveTabFromPinnedToPinned;
diff --git a/src/ui/functions/moveTabFromRootToPinned.ts b/src/ui/functions/moveTabFromRootToPinned.ts
deleted file mode 100644
index 91b2097c..00000000
--- a/src/ui/functions/moveTabFromRootToPinned.ts
+++ /dev/null
@@ -1,13 +0,0 @@
-import { moveTab, pinTab } from "../../platform/repository/TabsRepository";
-
-const moveTabFromRootToPinned = async (
-  tabId: number,
-  windowId: number,
-  index: number,
-) => {
-  await moveTab(tabId, windowId, -1);
-  await pinTab(tabId);
-  await moveTab(tabId, windowId, index);
-};
-
-export default moveTabFromRootToPinned;
diff --git a/src/ui/functions/resolveDuplicatedTabs.ts b/src/ui/functions/resolveDuplicatedTabs.ts
deleted file mode 100644
index 37e55b4b..00000000
--- a/src/ui/functions/resolveDuplicatedTabs.ts
+++ /dev/null
@@ -1,14 +0,0 @@
-import { isSamePageTabs, type Tab } from "../../model/Tab";
-import { flatTabsInWindows, type Window } from "../../model/Window";
-import { closeTabs } from "../../platform/repository/TabsRepository";
-
-const resolveDuplicatedTabs = async (windows: Window[], targetTab: Tab) => {
-  const allTabs = flatTabsInWindows(windows);
-  const duplicateTabs = allTabs.filter(
-    (tab) => tab.id !== targetTab.id && isSamePageTabs(tab, targetTab),
-  );
-  const duplicateTabIds = duplicateTabs.map((t) => t.id);
-  await closeTabs(duplicateTabIds);
-};
-
-export default resolveDuplicatedTabs;
diff --git a/src/ui/options/TabSearchForm.tsx b/src/ui/options/TabSearchForm.tsx
index 3362bd30..903cff24 100644
--- a/src/ui/options/TabSearchForm.tsx
+++ b/src/ui/options/TabSearchForm.tsx
@@ -21,13 +21,13 @@ import { useCallback, useContext, useEffect, useRef, useState } from "react";
 import t from "../../i18n/Translations";
 import type { Tab } from "../../model/Tab";
 import { findTabsByTitleOrUrl } from "../../model/Window";
+import { groupTabsBySearchKeyword } from "../../platform/repository/TabGroupRepository";
 import {
   focusTab,
   getRecentActiveTabs,
 } from "../../platform/repository/TabsRepository";
 import TabItem from "../components/TabItem";
 import { WindowsContext, WindowsProvider } from "../contexts/WindowsContext";
-import groupTabsBySearchKeyword from "../functions/groupTabsBySearchKeyword";
 
 const smoothScrollTo = (container: HTMLElement, targetScrollTop: number) => {
   const startScrollTop = container.scrollTop;
diff --git a/src/ui/popup/SearchResult.tsx b/src/ui/popup/SearchResult.tsx
index 90e46ca7..037795c0 100644
--- a/src/ui/popup/SearchResult.tsx
+++ b/src/ui/popup/SearchResult.tsx
@@ -11,13 +11,13 @@ import { useContext, useEffect, useRef, useState } from "react";
 import t from "../../i18n/Translations";
 import type { Tab } from "../../model/Tab";
 import { findTabsByTitleOrUrl } from "../../model/Window";
+import { groupTabsBySearchKeyword } from "../../platform/repository/TabGroupRepository";
 import {
   focusTab,
   getRecentActiveTabs,
 } from "../../platform/repository/TabsRepository";
 import TabItem from "../components/TabItem";
 import { WindowsContext } from "../contexts/WindowsContext";
-import groupTabsBySearchKeyword from "../functions/groupTabsBySearchKeyword";
 
 type SearchResultProps = {
   searchText: string;