feat(webui): improve sidebar performance

webui/src/tests/app-layout.test.tsx

@@ -992,6 +992,73 @@ describe("App layout", () => {
     );
   });
 
+  it("opens search from the keyboard shortcut", async () => {
+    mockSessions = [
+      {
+        key: "websocket:chat-a",
+        channel: "websocket",
+        chatId: "chat-a",
+        createdAt: "2026-04-16T10:00:00Z",
+        updatedAt: "2026-04-16T10:00:00Z",
+        preview: "Existing chat",
+      },
+    ];
+
+    render(<App />);
+
+    await waitFor(() => expect(connectSpy).toHaveBeenCalled());
+    fireEvent.keyDown(window, { key: "k", metaKey: true });
+
+    const dialog = await screen.findByRole("dialog", { name: "Search" });
+    expect(within(dialog).queryByText("Global actions")).not.toBeInTheDocument();
+    expect(within(dialog).getByText("Existing chat")).toBeInTheDocument();
+
+    const textbox = within(dialog).getByRole("textbox", { name: "Search" });
+    fireEvent.change(textbox, { target: { value: "missing" } });
+    expect(within(dialog).queryByText("Existing chat")).not.toBeInTheDocument();
+
+    fireEvent.change(textbox, { target: { value: "existing" } });
+    expect(within(dialog).getByText("Existing chat")).toBeInTheDocument();
+
+    fireEvent.keyDown(textbox, { key: "Enter" });
+    await waitFor(() =>
+      expect(screen.queryByRole("dialog", { name: "Search" })).not.toBeInTheDocument(),
+    );
+    expect(createChatSpy).not.toHaveBeenCalled();
+  });
+
+  it("keeps large sidebars light while search still covers every chat", async () => {
+    mockSessions = Array.from({ length: 170 }, (_, index) => {
+      const chatId = `chat-${index}`;
+      return {
+        key: `websocket:${chatId}`,
+        channel: "websocket" as const,
+        chatId,
+        createdAt: new Date(Date.UTC(2026, 3, 16, 12, 0 - index)).toISOString(),
+        updatedAt: new Date(Date.UTC(2026, 3, 16, 12, 0 - index)).toISOString(),
+        title: index === 169 ? "Hidden target" : `Bulk chat ${index}`,
+        preview: "",
+      };
+    });
+
+    render(<App />);
+
+    await waitFor(() => expect(connectSpy).toHaveBeenCalled());
+    const sidebar = screen.getByRole("navigation", { name: "Sidebar navigation" });
+    await waitFor(() =>
+      expect(within(sidebar).getByRole("button", { name: "Bulk chat 0" })).toBeInTheDocument(),
+    );
+    expect(within(sidebar).queryByText("Hidden target")).not.toBeInTheDocument();
+    expect(within(sidebar).getByRole("button", { name: "Show 10 more" })).toBeInTheDocument();
+
+    fireEvent.click(within(sidebar).getByRole("button", { name: "Search" }));
+    const dialog = await screen.findByRole("dialog", { name: "Search" });
+    fireEvent.change(within(dialog).getByRole("textbox", { name: "Search" }), {
+      target: { value: "hidden" },
+    });
+    expect(within(dialog).getByText("Hidden target")).toBeInTheDocument();
+  });
+
   it("opens a blank start page without creating an empty chat", async () => {
     mockSessions = [
       {

webui/src/tests/i18n.test.tsx

@@ -78,6 +78,7 @@ describe("webui i18n", () => {
       const common = resource.common;
       expect(common.app.system.restarting).toBeTruthy();
       expect(common.sidebar.settings).toBeTruthy();
+      expect(common.chat.showMore).toBeTruthy();
       expect(common.settings.sidebar.title).toBeTruthy();
       expect(common.settings.backToChat).toBeTruthy();
       for (const key of SETTINGS_NAV_KEYS) {