diff --git a/data-agent-frontend-nuxt/app/utils/clipboard.test.ts b/data-agent-frontend-nuxt/app/utils/clipboard.test.ts
new file mode 100644
index 000000000..36c54fde2
--- /dev/null
+++ b/data-agent-frontend-nuxt/app/utils/clipboard.test.ts
@@ -0,0 +1,108 @@
+/*
+ * Copyright 2026 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { copyTextToClipboard } from './clipboard';
+
+/**
+ * Minimal fake DOM so the execCommand fallback can be exercised in the default
+ * node test environment (no jsdom dependency, matching the rest of the suite).
+ */
+function stubFakeDocument(execResult: boolean) {
+	const appended: unknown[] = [];
+	const execCommand = vi.fn().mockReturnValue(execResult);
+	const fakeDocument = {
+		createElement: vi.fn(() => ({
+			style: {} as Record<string, string>,
+			setAttribute: vi.fn(),
+			select: vi.fn(),
+			setSelectionRange: vi.fn(),
+			value: '',
+		})),
+		body: {
+			appendChild: vi.fn((el: unknown) => appended.push(el)),
+			removeChild: vi.fn((el: unknown) => {
+				const i = appended.indexOf(el);
+				if (i >= 0) appended.splice(i, 1);
+			}),
+		},
+		execCommand,
+	};
+	vi.stubGlobal('document', fakeDocument);
+	return { appended, execCommand };
+}
+
+describe('copyTextToClipboard', () => {
+	afterEach(() => {
+		vi.unstubAllGlobals();
+		vi.restoreAllMocks();
+	});
+
+	it('uses navigator.clipboard in a secure context', async () => {
+		const writeText = vi.fn().mockResolvedValue(undefined);
+		vi.stubGlobal('window', { isSecureContext: true });
+		vi.stubGlobal('navigator', { clipboard: { writeText } });
+
+		const result = await copyTextToClipboard('SELECT 1');
+
+		expect(result).toBe(true);
+		expect(writeText).toHaveBeenCalledWith('SELECT 1');
+	});
+
+	it('falls back to execCommand when writeText rejects', async () => {
+		const writeText = vi.fn().mockRejectedValue(new Error('denied'));
+		vi.stubGlobal('window', { isSecureContext: true });
+		vi.stubGlobal('navigator', { clipboard: { writeText } });
+		const { execCommand } = stubFakeDocument(true);
+
+		const result = await copyTextToClipboard('SELECT 1');
+
+		expect(result).toBe(true);
+		expect(execCommand).toHaveBeenCalledWith('copy');
+	});
+
+	it('falls back to execCommand over plain HTTP on a LAN IP', async () => {
+		// navigator.clipboard is undefined in a non-secure context.
+		vi.stubGlobal('window', { isSecureContext: false });
+		vi.stubGlobal('navigator', {});
+		const { execCommand } = stubFakeDocument(true);
+
+		const result = await copyTextToClipboard('hello world');
+
+		expect(result).toBe(true);
+		expect(execCommand).toHaveBeenCalledWith('copy');
+	});
+
+	it('returns false when execCommand reports failure', async () => {
+		vi.stubGlobal('window', { isSecureContext: false });
+		vi.stubGlobal('navigator', {});
+		stubFakeDocument(false);
+
+		const result = await copyTextToClipboard('hello world');
+
+		expect(result).toBe(false);
+	});
+
+	it('removes the temporary textarea after copying', async () => {
+		vi.stubGlobal('window', { isSecureContext: false });
+		vi.stubGlobal('navigator', {});
+		const { appended } = stubFakeDocument(true);
+
+		await copyTextToClipboard('cleanup check');
+
+		expect(appended).toHaveLength(0);
+	});
+});
diff --git a/data-agent-frontend-nuxt/app/utils/clipboard.ts b/data-agent-frontend-nuxt/app/utils/clipboard.ts
new file mode 100644
index 000000000..5316cf92d
--- /dev/null
+++ b/data-agent-frontend-nuxt/app/utils/clipboard.ts
@@ -0,0 +1,71 @@
+/*
+ * Copyright 2026 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Copy text to the clipboard with a fallback for non-secure contexts.
+ *
+ * The async Clipboard API (`navigator.clipboard`) is only available in secure
+ * contexts (HTTPS or localhost). When the app is served over plain HTTP on a
+ * LAN IP, `navigator.clipboard` is `undefined`, so we fall back to the legacy
+ * `document.execCommand('copy')` using a temporary textarea.
+ *
+ * @returns `true` if the copy succeeded, `false` otherwise.
+ */
+export async function copyTextToClipboard(text: string): Promise<boolean> {
+	// Preferred path: async Clipboard API (secure contexts only).
+	if (
+		typeof navigator !== 'undefined' &&
+		navigator.clipboard &&
+		typeof navigator.clipboard.writeText === 'function' &&
+		(typeof window === 'undefined' || window.isSecureContext !== false)
+	) {
+		try {
+			await navigator.clipboard.writeText(text);
+			return true;
+		} catch {
+			// Fall through to the legacy fallback below.
+		}
+	}
+
+	return copyWithExecCommand(text);
+}
+
+/**
+ * Legacy clipboard copy using a hidden textarea and `document.execCommand`.
+ * Works in non-secure contexts where `navigator.clipboard` is unavailable.
+ */
+function copyWithExecCommand(text: string): boolean {
+	if (typeof document === 'undefined') return false;
+
+	const textarea = document.createElement('textarea');
+	textarea.value = text;
+	// Keep it out of view and prevent scrolling/zooming side effects.
+	textarea.style.position = 'fixed';
+	textarea.style.top = '-9999px';
+	textarea.style.left = '-9999px';
+	textarea.setAttribute('readonly', '');
+
+	document.body.appendChild(textarea);
+	try {
+		textarea.select();
+		textarea.setSelectionRange(0, text.length);
+		return document.execCommand('copy');
+	} catch {
+		return false;
+	} finally {
+		document.body.removeChild(textarea);
+	}
+}
diff --git a/data-agent-frontend-nuxt/app/utils/markdown/markdown-plugin-highlight.ts b/data-agent-frontend-nuxt/app/utils/markdown/markdown-plugin-highlight.ts
index b4800a5f9..05ef4acee 100644
--- a/data-agent-frontend-nuxt/app/utils/markdown/markdown-plugin-highlight.ts
+++ b/data-agent-frontend-nuxt/app/utils/markdown/markdown-plugin-highlight.ts
@@ -21,6 +21,7 @@ import Python from 'highlight.js/lib/languages/python';
 import Json from 'highlight.js/lib/languages/json';
 import JavaScript from 'highlight.js/lib/languages/javascript';
 import type MarkdownIt from 'markdown-it';
+import { copyTextToClipboard } from '../clipboard';
 
 hljs.registerLanguage('sql', Sql);
 hljs.registerLanguage('json', Json);
@@ -92,9 +93,8 @@ if (typeof window !== 'undefined' && !window.copyCodeBlock) {
 
 		if (!decodedCode) return;
 
-		navigator.clipboard
-			.writeText(decodedCode)
-			.then(() => {
+		copyTextToClipboard(decodedCode).then((success) => {
+			if (success) {
 				btn.textContent = '已复制!';
 				btn.classList.add('copied');
 				window.__tipShow?.('复制成功');
@@ -102,14 +102,14 @@ if (typeof window !== 'undefined' && !window.copyCodeBlock) {
 					btn.textContent = originalText;
 					btn.classList.remove('copied');
 				}, 2000);
-			})
-			.catch(() => {
+			} else {
 				btn.textContent = '复制失败';
 				window.__tipShow?.('复制失败', { color: 'error', icon: 'mdi-alert-circle' });
 				setTimeout(() => {
 					btn.textContent = originalText;
 				}, 2000);
-			});
+			}
+		});
 	};
 }