diff --git a/frontend/src/app/workspace/agents/[agent_name]/chats/[thread_id]/page.tsx b/frontend/src/app/workspace/agents/[agent_name]/chats/[thread_id]/page.tsx
index 62e256026..128eba6c3 100644
--- a/frontend/src/app/workspace/agents/[agent_name]/chats/[thread_id]/page.tsx
+++ b/frontend/src/app/workspace/agents/[agent_name]/chats/[thread_id]/page.tsx
@@ -259,10 +259,10 @@ export default function AgentChatPage() {
           <div className="relative flex size-full min-h-0 justify-between">
             <header
               className={cn(
-                "absolute top-0 right-0 left-0 z-30 flex h-12 shrink-0 items-center gap-2 px-2 sm:px-4",
+                "absolute top-0 right-0 left-0 flex h-12 shrink-0 items-center gap-2 px-2 sm:px-4",
                 isWelcomeMode
-                  ? "bg-background/0 backdrop-blur-none"
-                  : "bg-background/80 shadow-xs backdrop-blur",
+                  ? "bg-background/0 z-40 backdrop-blur-none"
+                  : "bg-background/80 z-30 shadow-xs backdrop-blur",
               )}
             >
               <SidebarTrigger className="md:hidden" />
diff --git a/frontend/src/components/workspace/chats/chat-page.tsx b/frontend/src/components/workspace/chats/chat-page.tsx
index 2c5b6e287..a4b66f8de 100644
--- a/frontend/src/components/workspace/chats/chat-page.tsx
+++ b/frontend/src/components/workspace/chats/chat-page.tsx
@@ -280,10 +280,10 @@ export default function ChatPage() {
           <div className="relative flex size-full min-h-0 justify-between">
             <header
               className={cn(
-                "absolute top-0 right-0 left-0 z-30 flex h-12 shrink-0 items-center gap-2 px-2 sm:px-4",
+                "absolute top-0 right-0 left-0 flex h-12 shrink-0 items-center gap-2 px-2 sm:px-4",
                 isWelcomeMode
-                  ? "bg-background/0 backdrop-blur-none"
-                  : "bg-background/80 shadow-xs backdrop-blur",
+                  ? "bg-background/0 z-40 backdrop-blur-none"
+                  : "bg-background/80 z-30 shadow-xs backdrop-blur",
               )}
             >
               {!isMock && <SidebarTrigger className="md:hidden" />}
diff --git a/frontend/tests/e2e/agent-chat.spec.ts b/frontend/tests/e2e/agent-chat.spec.ts
index 9993a87e3..807d1a1be 100644
--- a/frontend/tests/e2e/agent-chat.spec.ts
+++ b/frontend/tests/e2e/agent-chat.spec.ts
@@ -47,6 +47,54 @@ test.describe("Agent chat", () => {
     ).toBeVisible();
   });
 
+  test("mobile agent welcome keeps the sidebar trigger clickable", async ({
+    page,
+  }) => {
+    await page.setViewportSize({ width: 390, height: 664 });
+    mockLangGraphAPI(page, {
+      agents: [
+        {
+          ...MOCK_AGENTS[0]!,
+          description: "这是一个用于验证移动端欢迎页布局的测试智能体。".repeat(
+            16,
+          ),
+        },
+      ],
+    });
+
+    await page.goto("/workspace/agents/test-agent/chats/new");
+    await page.evaluate(() => {
+      document.cookie = "locale=zh-CN; path=/; SameSite=Lax";
+    });
+    await page.reload();
+
+    const sidebarTrigger = page
+      .locator("[data-sidebar='trigger']:visible")
+      .first();
+    await expect(sidebarTrigger).toBeVisible({ timeout: 15_000 });
+    const triggerBox = await sidebarTrigger.boundingBox();
+    expect(triggerBox).not.toBeNull();
+    const triggerReceivesPointerEvents = await page.evaluate(
+      ({ x, y }) => {
+        const trigger = document.elementFromPoint(x, y);
+        return trigger?.closest("[data-sidebar='trigger']") !== null;
+      },
+      {
+        x: triggerBox!.x + triggerBox!.width / 2,
+        y: triggerBox!.y + triggerBox!.height / 2,
+      },
+    );
+    expect(triggerReceivesPointerEvents).toBe(true);
+    await page.mouse.click(
+      triggerBox!.x + triggerBox!.width / 2,
+      triggerBox!.y + triggerBox!.height / 2,
+    );
+
+    await expect(
+      page.locator("[data-mobile='true'][data-sidebar='sidebar']"),
+    ).toBeVisible();
+  });
+
   test("keeps new-chat drafts isolated between agents", async ({ page }) => {
     mockLangGraphAPI(page, { agents: MOCK_AGENTS });
 
diff --git a/frontend/tests/e2e/sidebar.spec.ts b/frontend/tests/e2e/sidebar.spec.ts
index 15a8c19b8..a93c746ca 100644
--- a/frontend/tests/e2e/sidebar.spec.ts
+++ b/frontend/tests/e2e/sidebar.spec.ts
@@ -77,10 +77,14 @@ test.describe("Sidebar navigation", () => {
   test("mobile welcome layout stays within viewport and opens sidebar", async ({
     page,
   }) => {
-    await page.setViewportSize({ width: 390, height: 844 });
+    await page.setViewportSize({ width: 390, height: 664 });
     mockLangGraphAPI(page);
 
     await page.goto("/workspace/chats/new");
+    await page.evaluate(() => {
+      document.cookie = "locale=zh-CN; path=/; SameSite=Lax";
+    });
+    await page.reload();
 
     const viewportWidth = page.viewportSize()?.width ?? 390;
     const expectInsideViewport = async (
@@ -93,7 +97,7 @@ test.describe("Sidebar navigation", () => {
       expect(box!.x + box!.width).toBeLessThanOrEqual(viewportWidth + 1);
     };
 
-    await expectInsideViewport(page.getByText(/Welcome to|欢迎使用/).first());
+    await expectInsideViewport(page.getByText(/欢迎使用 🦌 DeerFlow/).first());
     await expectInsideViewport(page.getByRole("textbox").first());
     await expectInsideViewport(page.locator("[data-slot='suggestions-list']"));
 
@@ -101,7 +105,23 @@ test.describe("Sidebar navigation", () => {
       .locator("[data-sidebar='trigger']:visible")
       .first();
     await expect(mobileSidebarTrigger).toBeVisible();
-    await mobileSidebarTrigger.click();
+    const triggerBox = await mobileSidebarTrigger.boundingBox();
+    expect(triggerBox).not.toBeNull();
+    const triggerReceivesPointerEvents = await page.evaluate(
+      ({ x, y }) => {
+        const trigger = document.elementFromPoint(x, y);
+        return trigger?.closest("[data-sidebar='trigger']") !== null;
+      },
+      {
+        x: triggerBox!.x + triggerBox!.width / 2,
+        y: triggerBox!.y + triggerBox!.height / 2,
+      },
+    );
+    expect(triggerReceivesPointerEvents).toBe(true);
+    await page.mouse.click(
+      triggerBox!.x + triggerBox!.width / 2,
+      triggerBox!.y + triggerBox!.height / 2,
+    );
 
     const mobileSidebar = page.locator(
       "[data-mobile='true'][data-sidebar='sidebar']",