diff --git a/apps/web/src/app/__tests__/collections-new.test.tsx b/apps/web/src/app/__tests__/collections-new.test.tsx
index ff0678c4..2b18c088 100644
--- a/apps/web/src/app/__tests__/collections-new.test.tsx
+++ b/apps/web/src/app/__tests__/collections-new.test.tsx
@@ -52,7 +52,10 @@ describe("NewCollectionPage", () => {
     const description = screen.getByLabelText("description");
 
     expect(name).toHaveAttribute("aria-describedby", "name-counter");
-    expect(description).toHaveAttribute("aria-describedby", "description-counter");
+    expect(description).toHaveAttribute(
+      "aria-describedby",
+      "description-counter",
+    );
     expect(screen.getByText("0/100")).toHaveAttribute("id", "name-counter");
     expect(screen.getByText("0/500")).toHaveAttribute(
       "id",
diff --git a/apps/web/src/app/__tests__/home.test.tsx b/apps/web/src/app/__tests__/home.test.tsx
index 3224fde5..b550ed00 100644
--- a/apps/web/src/app/__tests__/home.test.tsx
+++ b/apps/web/src/app/__tests__/home.test.tsx
@@ -52,7 +52,11 @@ describe("Home page", () => {
 
     // Add additional assertions to increase coverage on page.tsx guest view
     expect(screen.getByText(/Research output hosting/)).toBeInTheDocument();
-    expect(screen.getByText(/OpenShelf は、論文・スライド・補足資料などをまとめて管理し/)).toBeInTheDocument();
+    expect(
+      screen.getByText(
+        /OpenShelf は、論文・スライド・補足資料などをまとめて管理し/,
+      ),
+    ).toBeInTheDocument();
     expect(screen.getByText(/1\. 成果物をまとめる/)).toBeInTheDocument();
     expect(screen.getByText(/2\. 公開範囲を選ぶ/)).toBeInTheDocument();
     expect(screen.getByText(/3\. 永続URLで共有/)).toBeInTheDocument();
@@ -131,10 +135,15 @@ describe("Home page", () => {
     expect(screen.getAllByText("公開")).toHaveLength(1);
   });
 
-
   it("handles apiFetch returning not ok", async () => {
-    authState = { user: { id: "user-1", name: "Alice" }, loading: false, login };
-    vi.mocked(apiFetch).mockResolvedValue(new Response("error", { status: 500 }));
+    authState = {
+      user: { id: "user-1", name: "Alice" },
+      loading: false,
+      login,
+    };
+    vi.mocked(apiFetch).mockResolvedValue(
+      new Response("error", { status: 500 }),
+    );
     render(<Home />);
     await waitFor(() => {
       expect(screen.getByText("まだ成果物がありません")).toBeInTheDocument();
@@ -142,7 +151,11 @@ describe("Home page", () => {
   });
 
   it("handles apiFetch error gracefully", async () => {
-    authState = { user: { id: "user-1", name: "Alice" }, loading: false, login };
+    authState = {
+      user: { id: "user-1", name: "Alice" },
+      loading: false,
+      login,
+    };
     vi.mocked(apiFetch).mockRejectedValue(new Error("Network error"));
     render(<Home />);
     await waitFor(() => {
diff --git a/apps/web/src/app/__tests__/paper-edit-page.test.tsx b/apps/web/src/app/__tests__/paper-edit-page.test.tsx
index 3d08fb10..8a2f4e91 100644
--- a/apps/web/src/app/__tests__/paper-edit-page.test.tsx
+++ b/apps/web/src/app/__tests__/paper-edit-page.test.tsx
@@ -1,4 +1,10 @@
-import { cleanup, fireEvent, render, screen, waitFor } from "@testing-library/react";
+import {
+  cleanup,
+  fireEvent,
+  render,
+  screen,
+  waitFor,
+} from "@testing-library/react";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import PaperEditPage from "../papers/[id]/edit/page";
 import { apiFetch } from "@/lib/api";
@@ -89,13 +95,17 @@ describe("PaperEditPage", () => {
       target: { value: "Updated title" },
     });
 
-    expect(screen.getByText(`${"Updated title".length}/300`)).toBeInTheDocument();
+    expect(
+      screen.getByText(`${"Updated title".length}/300`),
+    ).toBeInTheDocument();
 
     fireEvent.change(screen.getByLabelText(/概要/i), {
       target: { value: "Updated abstract" },
     });
 
-    expect(screen.getByText(`${"Updated abstract".length}/5000`)).toBeInTheDocument();
+    expect(
+      screen.getByText(`${"Updated abstract".length}/5000`),
+    ).toBeInTheDocument();
 
     fireEvent.click(screen.getByLabelText(/公開ページに閲覧数を表示する/i));
     fireEvent.change(screen.getByLabelText(/タグ/i), {
@@ -141,7 +151,8 @@ describe("PaperEditPage", () => {
     const patchCall = vi
       .mocked(apiFetch)
       .mock.calls.find(
-        ([url, init]) => url === "/api/papers/paper-1" && init?.method === "PATCH",
+        ([url, init]) =>
+          url === "/api/papers/paper-1" && init?.method === "PATCH",
       );
     const patchBody = JSON.parse((patchCall?.[1]?.body as string) ?? "{}");
     expect(patchBody).toMatchObject({
@@ -321,14 +332,19 @@ describe("PaperEditPage", () => {
 
     render(<PaperEditPage />);
     expect(await screen.findByDisplayValue("Initial")).toBeInTheDocument();
-    fireEvent.change(screen.getByLabelText(/タイトル/i), { target: { value: " " } });
+    fireEvent.change(screen.getByLabelText(/タイトル/i), {
+      target: { value: " " },
+    });
     fireEvent.click(screen.getByRole("button", { name: "保存する" }));
 
-    expect(await screen.findByText("タイトルを入力してください。")).toBeInTheDocument();
+    expect(
+      await screen.findByText("タイトルを入力してください。"),
+    ).toBeInTheDocument();
     const patchCalls = vi
       .mocked(apiFetch)
       .mock.calls.filter(
-        ([url, req]) => url === "/api/papers/paper-1" && req?.method === "PATCH",
+        ([url, req]) =>
+          url === "/api/papers/paper-1" && req?.method === "PATCH",
       );
     expect(patchCalls).toHaveLength(0);
   });
@@ -363,14 +379,17 @@ describe("PaperEditPage", () => {
 
     render(<PaperEditPage />);
     expect(await screen.findByDisplayValue("Initial")).toBeInTheDocument();
-    fireEvent.change(screen.getByLabelText(/発表年/i), { target: { value: "" } });
+    fireEvent.change(screen.getByLabelText(/発表年/i), {
+      target: { value: "" },
+    });
     fireEvent.click(screen.getByRole("button", { name: "保存する" }));
 
     const patchCall = await waitFor(() =>
       vi
         .mocked(apiFetch)
         .mock.calls.find(
-          ([url, req]) => url === "/api/papers/paper-1" && req?.method === "PATCH",
+          ([url, req]) =>
+            url === "/api/papers/paper-1" && req?.method === "PATCH",
         ),
     );
     const patchBody = JSON.parse((patchCall?.[1]?.body as string) ?? "{}");
@@ -510,7 +529,8 @@ describe("PaperEditPage", () => {
       vi
         .mocked(apiFetch)
         .mock.calls.find(
-          ([url, req]) => url === "/api/papers/paper-1" && req?.method === "PATCH",
+          ([url, req]) =>
+            url === "/api/papers/paper-1" && req?.method === "PATCH",
         ),
     );
     const patchBody = JSON.parse((patchCall?.[1]?.body as string) ?? "{}");
diff --git a/apps/web/src/app/__tests__/settings-page.test.tsx b/apps/web/src/app/__tests__/settings-page.test.tsx
index 63b6335b..03d8a418 100644
--- a/apps/web/src/app/__tests__/settings-page.test.tsx
+++ b/apps/web/src/app/__tests__/settings-page.test.tsx
@@ -204,7 +204,9 @@ describe("SettingsPage", () => {
   it("shows github username in preview when display name is blank", () => {
     render(<SettingsPage />);
 
-    fireEvent.change(screen.getByLabelText("表示名"), { target: { value: "   " } });
+    fireEvent.change(screen.getByLabelText("表示名"), {
+      target: { value: "   " },
+    });
 
     expect(screen.getByText("alice")).toBeInTheDocument();
   });
diff --git a/apps/web/src/app/invites/page.tsx b/apps/web/src/app/invites/page.tsx
index e2ba982b..b3d5aa58 100644
--- a/apps/web/src/app/invites/page.tsx
+++ b/apps/web/src/app/invites/page.tsx
@@ -26,9 +26,9 @@ export default function InvitesPage() {
   const router = useRouter();
   const [invites, setInvites] = useState<ReceivedInvite[]>([]);
   const [fetching, setFetching] = useState(true);
-  const [processingById, setProcessingById] = useState<Map<string, InviteAction>>(
-    () => new Map(),
-  );
+  const [processingById, setProcessingById] = useState<
+    Map<string, InviteAction>
+  >(() => new Map());
 
   useEffect(() => {
     if (!loading && !user) router.push("/");
@@ -82,7 +82,9 @@ export default function InvitesPage() {
               : i,
           ),
         );
-        toast.success(action === "accept" ? "招待を承認しました" : "招待を拒否しました");
+        toast.success(
+          action === "accept" ? "招待を承認しました" : "招待を拒否しました",
+        );
       } else {
         toast.error("処理に失敗しました");
       }
@@ -201,7 +203,13 @@ export default function InvitesPage() {
                         {processingAction === "accept" && (
                           <Spinner className="h-4 w-4" />
                         )}
-                        <span className={processingAction === "accept" ? "sr-only" : undefined}>
+                        <span
+                          className={
+                            processingAction === "accept"
+                              ? "sr-only"
+                              : undefined
+                          }
+                        >
                           承認
                         </span>
                       </button>
@@ -215,16 +223,24 @@ export default function InvitesPage() {
                         {processingAction === "decline" && (
                           <Spinner className="h-4 w-4" />
                         )}
-                        <span className={processingAction === "decline" ? "sr-only" : undefined}>
+                        <span
+                          className={
+                            processingAction === "decline"
+                              ? "sr-only"
+                              : undefined
+                          }
+                        >
                           拒否
                         </span>
                       </button>
                     </div>
                   ) : (
-                    <div className="shrink-0 text-xs text-gray-400">対応済み</div>
+                    <div className="shrink-0 text-xs text-gray-400">
+                      対応済み
+                    </div>
                   )}
                 </div>
-            </li>
+              </li>
             );
           })}
         </ul>
diff --git a/apps/web/src/app/orgs/[slug]/__tests__/org-page-client.test.tsx b/apps/web/src/app/orgs/[slug]/__tests__/org-page-client.test.tsx
index 05bc9545..7239ecfb 100644
--- a/apps/web/src/app/orgs/[slug]/__tests__/org-page-client.test.tsx
+++ b/apps/web/src/app/orgs/[slug]/__tests__/org-page-client.test.tsx
@@ -24,6 +24,7 @@ vi.mock("next/link", () => ({
 }));
 
 vi.mock("next/image", () => ({
+  // eslint-disable-next-line @next/next/no-img-element
   default: ({ alt = "image", ...props }: any) => <img alt={alt} {...props} />,
 }));
 
@@ -225,7 +226,8 @@ describe("OrgPageClient", () => {
         );
       }
       if (
-        url === "/api/orgs/lab/papers?paginate=1&autoYear=1&venue=ASE&category=report&page=2"
+        url ===
+        "/api/orgs/lab/papers?paginate=1&autoYear=1&venue=ASE&category=report&page=2"
       ) {
         return new Response(
           JSON.stringify({
@@ -273,14 +275,16 @@ describe("OrgPageClient", () => {
     expect(screen.getByText("2 / 3")).toBeInTheDocument();
 
     fireEvent.click(screen.getByRole("button", { name: "次へ" }));
-    const nextCall = replaceMock.mock.calls[replaceMock.mock.calls.length - 1][0];
+    const nextCall =
+      replaceMock.mock.calls[replaceMock.mock.calls.length - 1][0];
     expect(nextCall).toContain("/orgs/lab?");
     expect(nextCall).toContain("page=3");
     expect(nextCall).toContain("venue=ASE");
     expect(nextCall).toContain("category=report");
 
     fireEvent.click(screen.getByRole("button", { name: "前へ" }));
-    const prevCall = replaceMock.mock.calls[replaceMock.mock.calls.length - 1][0];
+    const prevCall =
+      replaceMock.mock.calls[replaceMock.mock.calls.length - 1][0];
     expect(prevCall).toContain("/orgs/lab?");
     expect(prevCall).toContain("page=1");
     expect(prevCall).toContain("venue=ASE");
@@ -340,14 +344,18 @@ describe("OrgPageClient", () => {
         );
       }
       if (url === "/api/orgs/lab/collections") {
-        return new Response(JSON.stringify({ collections: [] }), { status: 200 });
+        return new Response(JSON.stringify({ collections: [] }), {
+          status: 200,
+        });
       }
       throw new Error(`Unexpected request: ${String(url)}`);
     });
 
     render(<OrgPageClient slug="lab" />);
     expect(await screen.findByText("Research Lab")).toBeInTheDocument();
-    expect(screen.queryByRole("link", { name: "⚙ 設定" })).not.toBeInTheDocument();
+    expect(
+      screen.queryByRole("link", { name: "⚙ 設定" }),
+    ).not.toBeInTheDocument();
     expect(
       screen.queryByRole("link", { name: "+ 成果物を追加" }),
     ).not.toBeInTheDocument();
@@ -381,14 +389,18 @@ describe("OrgPageClient", () => {
         return new Response(JSON.stringify({ members: [] }), { status: 200 });
       }
       if (url === "/api/orgs/lab/collections") {
-        return new Response(JSON.stringify({ collections: [] }), { status: 200 });
+        return new Response(JSON.stringify({ collections: [] }), {
+          status: 200,
+        });
       }
       throw new Error(`Unexpected request: ${String(url)}`);
     });
 
     render(<OrgPageClient slug="lab" />);
     expect(await screen.findByText("Research Lab")).toBeInTheDocument();
-    expect(await screen.findByText("まだ成果物がありません")).toBeInTheDocument();
+    expect(
+      await screen.findByText("まだ成果物がありません"),
+    ).toBeInTheDocument();
   });
 
   it("applies explicit all-year filter when selecting empty year option", async () => {
@@ -431,7 +443,9 @@ describe("OrgPageClient", () => {
         return new Response(JSON.stringify({ members: [] }), { status: 200 });
       }
       if (url === "/api/orgs/lab/collections") {
-        return new Response(JSON.stringify({ collections: [] }), { status: 200 });
+        return new Response(JSON.stringify({ collections: [] }), {
+          status: 200,
+        });
       }
       throw new Error(`Unexpected request: ${String(url)}`);
     });
@@ -484,7 +498,9 @@ describe("OrgPageClient", () => {
         return new Response(JSON.stringify({ members: [] }), { status: 200 });
       }
       if (url === "/api/orgs/lab/collections") {
-        return new Response(JSON.stringify({ collections: [] }), { status: 200 });
+        return new Response(JSON.stringify({ collections: [] }), {
+          status: 200,
+        });
       }
       throw new Error(`Unexpected request: ${String(url)}`);
     });
@@ -534,13 +550,17 @@ describe("OrgPageClient", () => {
         return new Response(JSON.stringify({ members: [] }), { status: 200 });
       }
       if (url === "/api/orgs/lab/collections") {
-        return new Response(JSON.stringify({ collections: [] }), { status: 200 });
+        return new Response(JSON.stringify({ collections: [] }), {
+          status: 200,
+        });
       }
       throw new Error(`Unexpected request: ${String(url)}`);
     });
 
     render(<OrgPageClient slug="lab" />);
     expect(await screen.findByText("Research Lab")).toBeInTheDocument();
-    expect(await screen.findByText("まだ成果物がありません")).toBeInTheDocument();
+    expect(
+      await screen.findByText("まだ成果物がありません"),
+    ).toBeInTheDocument();
   });
 });
diff --git a/apps/web/src/app/orgs/[slug]/settings/__tests__/page.test.tsx b/apps/web/src/app/orgs/[slug]/settings/__tests__/page.test.tsx
index 83e111a3..4356dd07 100644
--- a/apps/web/src/app/orgs/[slug]/settings/__tests__/page.test.tsx
+++ b/apps/web/src/app/orgs/[slug]/settings/__tests__/page.test.tsx
@@ -69,6 +69,7 @@ vi.mock("next/link", () => ({
 
 vi.mock("next/image", () => ({
   default: ({ src, alt, ...props }: any) => (
+    // eslint-disable-next-line @next/next/no-img-element
     <img src={typeof src === "string" ? src : ""} alt={alt} {...props} />
   ),
 }));
diff --git a/apps/web/src/app/papers/[id]/__tests__/badge-snippet.test.tsx b/apps/web/src/app/papers/[id]/__tests__/badge-snippet.test.tsx
index 1583feae..d76655a8 100644
--- a/apps/web/src/app/papers/[id]/__tests__/badge-snippet.test.tsx
+++ b/apps/web/src/app/papers/[id]/__tests__/badge-snippet.test.tsx
@@ -19,6 +19,11 @@ vi.mock("@/components/toast", () => ({
   },
 }));
 
+vi.mock("next/image", () => ({
+  // eslint-disable-next-line @next/next/no-img-element
+  default: ({ unoptimized: _unoptimized, ...props }: any) => <img {...props} />,
+}));
+
 describe("BadgeSnippet", () => {
   beforeEach(() => {
     vi.clearAllMocks();
diff --git a/apps/web/src/app/papers/[id]/__tests__/page-metadata.test.tsx b/apps/web/src/app/papers/[id]/__tests__/page-metadata.test.tsx
index 307ff421..6cd75a20 100644
--- a/apps/web/src/app/papers/[id]/__tests__/page-metadata.test.tsx
+++ b/apps/web/src/app/papers/[id]/__tests__/page-metadata.test.tsx
@@ -91,11 +91,9 @@ describe("papers/[id]/page metadata", () => {
     expect(metadata.openGraph?.title).toBe("成果物詳細 | OpenShelf");
   });
 
-
   it("generates generic metadata when id is invalid", async () => {
     // Generate metadata without await as the component is sync for generating metadata via props
     const metadata = await generateMetadata({ params: { id: "../bad" } });
     expect(metadata.title).toBe("成果物詳細 | OpenShelf");
   });
-
 });
diff --git a/apps/web/src/app/papers/[id]/__tests__/paper-detail-client.test.tsx b/apps/web/src/app/papers/[id]/__tests__/paper-detail-client.test.tsx
index e82a3b10..0bfd9d19 100644
--- a/apps/web/src/app/papers/[id]/__tests__/paper-detail-client.test.tsx
+++ b/apps/web/src/app/papers/[id]/__tests__/paper-detail-client.test.tsx
@@ -40,7 +40,8 @@ vi.mock("next/link", () => ({
 }));
 
 vi.mock("next/image", () => ({
-  default: ({ src, alt, ...props }: any) => (
+  default: ({ src, alt, unoptimized: _unoptimized, ...props }: any) => (
+    // eslint-disable-next-line @next/next/no-img-element
     <img src={typeof src === "string" ? src : ""} alt={alt} {...props} />
   ),
 }));
@@ -417,7 +418,9 @@ describe("PaperDetailClient", () => {
     const slideRow = screen.getByText("deck.pptx").closest("li");
     expect(slideRow).not.toBeNull();
     fireEvent.click(
-      within(slideRow!).getByRole("button", { name: "deck.pptxをダウンロード" }),
+      within(slideRow!).getByRole("button", {
+        name: "deck.pptxをダウンロード",
+      }),
     );
 
     await waitFor(() => {
@@ -748,18 +751,21 @@ describe("PaperDetailClient", () => {
     [401, "ログインが必要です"],
     [404, "成果物が見つかりません"],
     [500, "成果物の取得に失敗しました"],
-  ])("maps paper fetch status %s to its error message", async (status, message) => {
-    vi.mocked(apiFetch).mockResolvedValue(new Response("error", { status }));
-
-    render(
-      <PaperDetailClient
-        paperId="paper-1"
-        siteBase="https://openshelf.example"
-      />,
-    );
+  ])(
+    "maps paper fetch status %s to its error message",
+    async (status, message) => {
+      vi.mocked(apiFetch).mockResolvedValue(new Response("error", { status }));
+
+      render(
+        <PaperDetailClient
+          paperId="paper-1"
+          siteBase="https://openshelf.example"
+        />,
+      );
 
-    expect(await screen.findByText(message)).toBeInTheDocument();
-  });
+      expect(await screen.findByText(message)).toBeInTheDocument();
+    },
+  );
 
   it("shows an error when API request fails entirely", async () => {
     vi.mocked(apiFetch).mockRejectedValue(new Error("Network Error"));
@@ -775,5 +781,4 @@ describe("PaperDetailClient", () => {
       await screen.findByText("成果物の取得に失敗しました"),
     ).toBeInTheDocument();
   });
-
 });
diff --git a/apps/web/src/app/papers/[id]/badge-snippet.tsx b/apps/web/src/app/papers/[id]/badge-snippet.tsx
index 28e35429..be5dcb46 100644
--- a/apps/web/src/app/papers/[id]/badge-snippet.tsx
+++ b/apps/web/src/app/papers/[id]/badge-snippet.tsx
@@ -1,6 +1,7 @@
 "use client";
 
 import { toast } from "@/components/toast";
+import Image from "next/image";
 import { useMemo } from "react";
 
 type BadgeSnippetProps = {
@@ -110,10 +111,14 @@ export function BadgeSnippet({ paperId, title, siteBase }: BadgeSnippetProps) {
       </h2>
 
       <div className="mb-4 rounded-md border border-gray-200 bg-gray-50 p-3 dark:border-gray-700 dark:bg-gray-900/30">
-        <img
+        <Image
           src={badgePreviewUrl}
           alt={`OpenShelf badge preview for ${title}`}
+          width={0}
+          height={0}
+          sizes="100vw"
           className="h-5 w-auto"
+          unoptimized
         />
       </div>
 
diff --git a/apps/web/src/app/papers/[id]/cite-button.tsx b/apps/web/src/app/papers/[id]/cite-button.tsx
index 086fb330..ae5c1d15 100644
--- a/apps/web/src/app/papers/[id]/cite-button.tsx
+++ b/apps/web/src/app/papers/[id]/cite-button.tsx
@@ -121,9 +121,7 @@ export function CiteButton({ paperId }: CiteButtonProps) {
                 <span className="flex items-center gap-2">
                   <Spinner className="h-3 w-3" />
                   <span aria-hidden="true">生成中...</span>
-                  <span className="sr-only">
-                    {option.label} の引用を生成中
-                  </span>
+                  <span className="sr-only">{option.label} の引用を生成中</span>
                 </span>
               ) : (
                 option.label
diff --git a/apps/web/src/app/papers/[id]/paper-detail-client.tsx b/apps/web/src/app/papers/[id]/paper-detail-client.tsx
index e9abdf4b..e4aa9b5d 100644
--- a/apps/web/src/app/papers/[id]/paper-detail-client.tsx
+++ b/apps/web/src/app/papers/[id]/paper-detail-client.tsx
@@ -836,11 +836,14 @@ export default function PaperDetailClient({
                 className="rounded-md border border-gray-200 p-2 dark:border-gray-700"
               >
                 {imagePreviewUrls[img.id] ? (
-                  <img
+                  <Image
                     src={imagePreviewUrls[img.id]}
                     alt={img.filename}
+                    width={0}
+                    height={0}
+                    sizes="100vw"
                     className="h-auto w-full rounded"
-                    loading="lazy"
+                    unoptimized
                   />
                 ) : failedImageIds.includes(img.id) ? (
                   <div className="flex h-[180px] items-center justify-center rounded bg-red-50 text-xs text-red-600 dark:bg-red-950/20 dark:text-red-400">
diff --git a/apps/web/src/app/upload/__tests__/page.test.tsx b/apps/web/src/app/upload/__tests__/page.test.tsx
index 88fd19ef..cc999461 100644
--- a/apps/web/src/app/upload/__tests__/page.test.tsx
+++ b/apps/web/src/app/upload/__tests__/page.test.tsx
@@ -82,7 +82,9 @@ describe("UploadPage", () => {
     fireEvent.change(screen.getByLabelText(/タイトル/i), {
       target: { value: "  My paper  " },
     });
-    expect(screen.getByText(`${"  My paper  ".length}/300`)).toBeInTheDocument();
+    expect(
+      screen.getByText(`${"  My paper  ".length}/300`),
+    ).toBeInTheDocument();
 
     fireEvent.change(screen.getByLabelText(/概要/i), {
       target: { value: "Abstract" },