diff --git a/.changeset/fix-web-clipboard-copy.md b/.changeset/fix-web-clipboard-copy.md
new file mode 100644
index 0000000000..3ec4efc565
--- /dev/null
+++ b/.changeset/fix-web-clipboard-copy.md
@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Fix clipboard copy actions in the web UI when served over plain HTTP.
diff --git a/apps/kimi-code/test/tui/components/panels/footer-goal-badge.test.ts b/apps/kimi-code/test/tui/components/panels/footer-goal-badge.test.ts
index 068761f7c6..365df3e4af 100644
--- a/apps/kimi-code/test/tui/components/panels/footer-goal-badge.test.ts
+++ b/apps/kimi-code/test/tui/components/panels/footer-goal-badge.test.ts
@@ -58,7 +58,7 @@ describe('FooterComponent — goal badge', () => {
 
   it('omits the badge when there is no goal', () => {
     const footer = new FooterComponent(baseState({ goal: null }));
-    expect(strip(footer.render(160)[0]!)).not.toMatch(/goal/);
+    expect(strip(footer.render(160)[0]!)).not.toContain('[goal');
   });
 
   it('shows status, elapsed, and a raw turn count for an unbounded active goal', () => {
@@ -116,7 +116,7 @@ describe('FooterComponent — goal badge', () => {
 
   it('hides the badge for a completed goal', () => {
     const footer = new FooterComponent(baseState({ goal: goal({ status: 'complete' }) }));
-    expect(strip(footer.render(160)[0]!)).not.toMatch(/goal/);
+    expect(strip(footer.render(160)[0]!)).not.toContain('[goal');
   });
 
   it('singularizes a single turn', () => {
diff --git a/apps/kimi-web/src/components/FilePreview.vue b/apps/kimi-web/src/components/FilePreview.vue
index 948e502166..5f0b08ec25 100644
--- a/apps/kimi-web/src/components/FilePreview.vue
+++ b/apps/kimi-web/src/components/FilePreview.vue
@@ -5,6 +5,7 @@ import { computed, inject, nextTick, provide, ref, watch } from 'vue';
 import { useI18n } from 'vue-i18n';
 import Markdown from './chat/Markdown.vue';
 import type { FileData, FilePreviewRequest } from '../types';
+import { copyTextToClipboard } from '../lib/clipboard';
 
 const { t } = useI18n();
 
@@ -251,18 +252,20 @@ const copiedPath = ref(false);
 
 function copyContent(): void {
   if (!props.file) return;
-  navigator.clipboard.writeText(sourceText.value).then(() => {
+  void copyTextToClipboard(sourceText.value).then((ok) => {
+    if (!ok) return;
     copied.value = true;
     setTimeout(() => { copied.value = false; }, 1400);
-  }).catch(() => {/* ignore */});
+  });
 }
 
 function copyPath(): void {
   if (!props.file) return;
-  navigator.clipboard.writeText(props.file.path).then(() => {
+  void copyTextToClipboard(props.file.path).then((ok) => {
+    if (!ok) return;
     copiedPath.value = true;
     setTimeout(() => { copiedPath.value = false; }, 1400);
-  }).catch(() => {/* ignore */});
+  });
 }
 
 // ---------------------------------------------------------------------------
diff --git a/apps/kimi-web/src/components/SessionRow.vue b/apps/kimi-web/src/components/SessionRow.vue
index 51e3e2786f..94c0b65ed5 100644
--- a/apps/kimi-web/src/components/SessionRow.vue
+++ b/apps/kimi-web/src/components/SessionRow.vue
@@ -5,6 +5,7 @@
 import { nextTick, onUnmounted, ref } from 'vue';
 import { useI18n } from 'vue-i18n';
 import type { Session } from '../types';
+import { copyTextToClipboard } from '../lib/clipboard';
 
 const { t } = useI18n();
 
@@ -84,11 +85,17 @@ function cancelRename(): void {
 
 // Copy session ID
 const copiedId = ref(false);
-function copySessionId(): void {
-  navigator.clipboard.writeText(props.session.id).then(() => {
-    copiedId.value = true;
-    setTimeout(() => { copiedId.value = false; }, 1200);
-  }).catch(() => {/* ignore */});
+const copyFailed = ref(false);
+async function copySessionId(): Promise<void> {
+  const ok = await copyTextToClipboard(props.session.id);
+  copiedId.value = ok;
+  copyFailed.value = !ok;
+  // Keep the menu open briefly so the result text is visible, then close.
+  setTimeout(() => {
+    copiedId.value = false;
+    copyFailed.value = false;
+    closeMenu();
+  }, 1500);
 }
 
 // Fork this session into a new child session
@@ -212,8 +219,14 @@ defineExpose({ closeMenu, cancelArchive });
 
     <!-- Kebab dropdown -->
     <div ref="menuRef" v-if="menuOpen" class="menu" @click.stop>
-      <button class="menu-item copy-id" @click.stop="copySessionId">
-        {{ copiedId ? '已复制 ✓' : '复制 Session ID ⧉' }}
+      <button class="menu-item copy-id" :class="{ failed: copyFailed }" @click.stop="copySessionId">
+        {{
+          copyFailed
+            ? t('sidebar.copyFailed')
+            : copiedId
+              ? t('sidebar.copied')
+              : t('sidebar.copySessionId')
+        }}
       </button>
       <div class="menu-divider" />
       <button class="menu-item" @click.stop="startRename">{{ t('sidebar.rename') }}</button>
@@ -375,6 +388,7 @@ defineExpose({ closeMenu, cancelArchive });
 }
 .menu-item:hover { background: var(--panel2); }
 .menu-item.archive { color: var(--err); }
+.menu-item.failed { color: var(--err); }
 
 .menu-divider {
   height: 1px;
diff --git a/apps/kimi-web/src/components/Sidebar.vue b/apps/kimi-web/src/components/Sidebar.vue
index ee6251e79a..ba1ab27e71 100644
--- a/apps/kimi-web/src/components/Sidebar.vue
+++ b/apps/kimi-web/src/components/Sidebar.vue
@@ -6,6 +6,7 @@
 import { computed, nextTick, onBeforeUnmount, ref } from 'vue';
 import { useI18n } from 'vue-i18n';
 import { serverEndpointLabel } from '../api/config';
+import { copyTextToClipboard } from '../lib/clipboard';
 import type { Session, WorkspaceGroup as WorkspaceGroupType, WorkspaceView } from '../types';
 import SessionRow from './SessionRow.vue';
 import WorkspaceGroup from './WorkspaceGroup.vue';
@@ -249,7 +250,7 @@ function closeGhMenu(): void {
 
 function copyPathFromMenu(): void {
   if (ghMenuTarget.value) {
-    void navigator.clipboard.writeText(ghMenuTarget.value.root);
+    void copyTextToClipboard(ghMenuTarget.value.root);
   }
   closeGhMenu();
 }
@@ -352,7 +353,7 @@ function closeWsMenu(): void {
 }
 
 function copyWsPath(ws: WorkspaceView): void {
-  void navigator.clipboard.writeText(ws.root);
+  void copyTextToClipboard(ws.root);
   closeWsMenu();
 }
 
diff --git a/apps/kimi-web/src/components/WarningToasts.vue b/apps/kimi-web/src/components/WarningToasts.vue
index c1fa64c98e..d7e3a2ace0 100644
--- a/apps/kimi-web/src/components/WarningToasts.vue
+++ b/apps/kimi-web/src/components/WarningToasts.vue
@@ -4,6 +4,7 @@
 import { onUnmounted, ref, watch } from 'vue';
 import { useI18n } from 'vue-i18n';
 import type { AppNotice, AppWarning } from '../api/types';
+import { copyTextToClipboard } from '../lib/clipboard';
 
 const props = defineProps<{ warnings: AppWarning[] }>();
 const emit = defineEmits<{ dismiss: [index: number] }>();
@@ -120,8 +121,8 @@ function toggleDetails(toast: ToastItem): void {
 }
 
 async function copyDetails(toast: ToastItem): Promise<void> {
-  if (!navigator.clipboard?.writeText) return;
-  await navigator.clipboard.writeText(formatWarningForCopy(toast.warning));
+  const ok = await copyTextToClipboard(formatWarningForCopy(toast.warning));
+  if (!ok) return;
   toast.copied = true;
   const prev = copiedTimers.get(toast.id);
   if (prev) clearTimeout(prev);
diff --git a/apps/kimi-web/src/components/chat/ChatHeader.vue b/apps/kimi-web/src/components/chat/ChatHeader.vue
index 9984eccae3..7e7d0b5598 100644
--- a/apps/kimi-web/src/components/chat/ChatHeader.vue
+++ b/apps/kimi-web/src/components/chat/ChatHeader.vue
@@ -5,6 +5,7 @@
 <script setup lang="ts">
 import { computed, nextTick, onUnmounted, ref } from 'vue';
 import { useI18n } from 'vue-i18n';
+import { copyTextToClipboard } from '../../lib/clipboard';
 
 const { t } = useI18n();
 
@@ -124,12 +125,13 @@ function onCopyFinalSummary(): void {
 const copiedId = ref(false);
 function copySessionId(): void {
   if (!props.sessionId) return;
-  navigator.clipboard.writeText(props.sessionId).then(() => {
+  void copyTextToClipboard(props.sessionId).then((ok) => {
+    if (!ok) return;
     copiedId.value = true;
     setTimeout(() => {
       copiedId.value = false;
     }, 1200);
-  }).catch(() => { /* ignore */ });
+  });
 }
 
 // ---------------------------------------------------------------------------
diff --git a/apps/kimi-web/src/components/chat/ChatPane.vue b/apps/kimi-web/src/components/chat/ChatPane.vue
index be7f5543cb..6eb280ceae 100644
--- a/apps/kimi-web/src/components/chat/ChatPane.vue
+++ b/apps/kimi-web/src/components/chat/ChatPane.vue
@@ -11,6 +11,7 @@ import AgentCard from './AgentCard.vue';
 import AgentGroup from './AgentGroup.vue';
 import MoonSpinner from '../MoonSpinner.vue';
 import { formatMessageTime } from '../../lib/formatMessageTime';
+import { copyTextToClipboard } from '../../lib/clipboard';
 import {
   assistantRenderBlocks,
   formatDuration,
@@ -296,7 +297,8 @@ function copyConversation(): void {
     }
   }
   const markdown = lines.join('\n\n---\n\n');
-  navigator.clipboard.writeText(markdown).then(() => {
+  void copyTextToClipboard(markdown).then((ok) => {
+    if (!ok) return;
     copiedConversation.value = true;
     emit('copyConversationCopied');
     if (copiedConversationTimer !== null) clearTimeout(copiedConversationTimer);
@@ -334,7 +336,8 @@ function finalSummaryText(): string {
 function copyFinalSummary(): void {
   const text = finalSummaryText();
   if (!text.trim()) return;
-  navigator.clipboard.writeText(text).then(() => {
+  void copyTextToClipboard(text).then((ok) => {
+    if (!ok) return;
     copiedConversation.value = true;
     emit('copyConversationCopied');
     if (copiedConversationTimer !== null) clearTimeout(copiedConversationTimer);
@@ -362,7 +365,8 @@ function copyAssistantRun(index: number): void {
   if (!turn) return;
   const text = assistantRunFinalText(index);
   if (!text.trim()) return;
-  navigator.clipboard.writeText(text).then(() => {
+  void copyTextToClipboard(text).then((ok) => {
+    if (!ok) return;
     copiedTurn.value = turn.id;
     if (copiedTimer !== null) clearTimeout(copiedTimer);
     copiedTimer = setTimeout(() => {
diff --git a/apps/kimi-web/src/components/chat/Markdown.vue b/apps/kimi-web/src/components/chat/Markdown.vue
index a626e0091f..b90f2afbad 100644
--- a/apps/kimi-web/src/components/chat/Markdown.vue
+++ b/apps/kimi-web/src/components/chat/Markdown.vue
@@ -7,6 +7,7 @@ import { useIsDark } from '../../composables/useIsDark';
 import type { FilePreviewRequest } from '../../types';
 import { collectFilePathAliases, findFilePathLinks } from '../../lib/filePathLinks';
 import { markdownRenderPlan } from '../../lib/markdownPerformance';
+import { copyTextToClipboard } from '../../lib/clipboard';
 // px-based CSS build (our app is px, not rem). Imported here so the styles
 // load wherever Markdown is used; scoped overrides below re-skin it to
 // Terminal Pro. Importing the same file from multiple components is a no-op
@@ -335,17 +336,13 @@ function diffLines(code: string): { cls: string; text: string }[] {
 // Copy state for local diff blocks (keyed by segment index).
 const copiedDiff = ref<number | null>(null);
 function copyDiff(code: string, idx: number) {
-  navigator.clipboard
-    .writeText(code)
-    .then(() => {
-      copiedDiff.value = idx;
-      setTimeout(() => {
-        copiedDiff.value = null;
-      }, 1400);
-    })
-    .catch(() => {
-      /* ignore */
-    });
+  void copyTextToClipboard(code).then((ok) => {
+    if (!ok) return;
+    copiedDiff.value = idx;
+    setTimeout(() => {
+      copiedDiff.value = null;
+    }, 1400);
+  });
 }
 </script>
 
diff --git a/apps/kimi-web/src/components/chat/OpenInMenu.vue b/apps/kimi-web/src/components/chat/OpenInMenu.vue
index fdf988348a..d210a86168 100644
--- a/apps/kimi-web/src/components/chat/OpenInMenu.vue
+++ b/apps/kimi-web/src/components/chat/OpenInMenu.vue
@@ -6,6 +6,7 @@
 import { computed, nextTick, onUnmounted, ref } from 'vue';
 import { useI18n } from 'vue-i18n';
 import { safeGetString, safeSetString, STORAGE_KEYS } from '../../lib/storage';
+import { copyTextToClipboard } from '../../lib/clipboard';
 
 const { t } = useI18n();
 
@@ -164,11 +165,10 @@ function handleQuickOpen(): void {
 const copiedPath = ref(false);
 async function copyPath(): Promise<void> {
   if (!props.workDir) return;
-  try {
-    await navigator.clipboard.writeText(props.workDir);
-    copiedPath.value = true;
-    setTimeout(() => { copiedPath.value = false; }, 1200);
-  } catch { /* ignore */ }
+  const ok = await copyTextToClipboard(props.workDir);
+  if (!ok) return;
+  copiedPath.value = true;
+  setTimeout(() => { copiedPath.value = false; }, 1200);
 }
 </script>
 
diff --git a/apps/kimi-web/src/components/chat/TasksPane.vue b/apps/kimi-web/src/components/chat/TasksPane.vue
index cec4883af6..8536aa2cf8 100644
--- a/apps/kimi-web/src/components/chat/TasksPane.vue
+++ b/apps/kimi-web/src/components/chat/TasksPane.vue
@@ -5,6 +5,7 @@
 import { reactive } from 'vue';
 import { useI18n } from 'vue-i18n';
 import type { TaskItem } from '../../types';
+import { copyTextToClipboard } from '../../lib/clipboard';
 
 defineProps<{ tasks: TaskItem[] }>();
 
@@ -47,13 +48,10 @@ function statusClass(state: string): string {
 }
 
 async function copyToClipboard(text: string, taskId: string, set: Set<string>): Promise<void> {
-  try {
-    await navigator.clipboard.writeText(text);
-    set.add(taskId);
-    setTimeout(() => set.delete(taskId), 1500);
-  } catch {
-    // Ignore clipboard failures (e.g. denied permission).
-  }
+  const ok = await copyTextToClipboard(text);
+  if (!ok) return;
+  set.add(taskId);
+  setTimeout(() => set.delete(taskId), 1500);
 }
 
 async function copyTaskCommand(task: TaskItem): Promise<void> {
diff --git a/apps/kimi-web/src/components/dialogs/LoginDialog.vue b/apps/kimi-web/src/components/dialogs/LoginDialog.vue
index 581411f436..f5bc30d0bd 100644
--- a/apps/kimi-web/src/components/dialogs/LoginDialog.vue
+++ b/apps/kimi-web/src/components/dialogs/LoginDialog.vue
@@ -5,6 +5,7 @@
 import { onMounted, onUnmounted, ref } from 'vue';
 import { useI18n } from 'vue-i18n';
 import { useDialogFocus } from '../../composables/useDialogFocus';
+import { copyTextToClipboard } from '../../lib/clipboard';
 
 const { t } = useI18n();
 
@@ -160,13 +161,10 @@ async function retryFlow(): Promise<void> {
 
 async function copyCode(): Promise<void> {
   if (!flow.value) return;
-  try {
-    await navigator.clipboard.writeText(flow.value.userCode);
-    copied.value = true;
-    setTimeout(() => { copied.value = false; }, 2000);
-  } catch {
-    // clipboard unavailable — ignore
-  }
+  const ok = await copyTextToClipboard(flow.value.userCode);
+  if (!ok) return;
+  copied.value = true;
+  setTimeout(() => { copied.value = false; }, 2000);
 }
 
 async function close(): Promise<void> {
diff --git a/apps/kimi-web/src/components/mobile/MobileSwitcherSheet.vue b/apps/kimi-web/src/components/mobile/MobileSwitcherSheet.vue
index cfa5dc2f6f..11998f8337 100644
--- a/apps/kimi-web/src/components/mobile/MobileSwitcherSheet.vue
+++ b/apps/kimi-web/src/components/mobile/MobileSwitcherSheet.vue
@@ -8,6 +8,7 @@
 import { onUnmounted, ref } from 'vue';
 import { useI18n } from 'vue-i18n';
 import type { Session, WorkspaceGroup, WorkspaceView } from '../../types';
+import { copyTextToClipboard } from '../../lib/clipboard';
 import BottomSheet from '../dialogs/BottomSheet.vue';
 
 const { t } = useI18n();
@@ -188,7 +189,7 @@ function toggleWsMenu(id: string): void {
   confirmingWsDeleteId.value = null;
 }
 function onCopyWsPath(ws: WorkspaceView): void {
-  void navigator.clipboard.writeText(ws.root);
+  void copyTextToClipboard(ws.root);
   wsMenuFor.value = null;
 }
 function onDeleteWorkspace(id: string): void {
diff --git a/apps/kimi-web/src/debug/KapDebugView.vue b/apps/kimi-web/src/debug/KapDebugView.vue
index f1f92f5ca6..4438b2d6e3 100644
--- a/apps/kimi-web/src/debug/KapDebugView.vue
+++ b/apps/kimi-web/src/debug/KapDebugView.vue
@@ -5,6 +5,7 @@
      Dev tooling: labels are intentionally not localized. -->
 <script setup lang="ts">
 import { computed, nextTick, ref, watch } from 'vue';
+import { copyTextToClipboard } from '../lib/clipboard';
 import {
   clearTrace,
   downloadTraceLog,
@@ -121,13 +122,10 @@ function entryJson(e: TraceEntry): string {
 }
 
 async function copyEntry(e: TraceEntry): Promise<void> {
-  try {
-    await navigator.clipboard.writeText(entryJson(e));
-    copiedId.value = e.id;
-    setTimeout(() => { if (copiedId.value === e.id) copiedId.value = null; }, 1500);
-  } catch {
-    // clipboard unavailable
-  }
+  const ok = await copyTextToClipboard(entryJson(e));
+  if (!ok) return;
+  copiedId.value = e.id;
+  setTimeout(() => { if (copiedId.value === e.id) copiedId.value = null; }, 1500);
 }
 
 function exportJsonl(): void {
diff --git a/apps/kimi-web/src/i18n/locales/en/sidebar.ts b/apps/kimi-web/src/i18n/locales/en/sidebar.ts
index c479adeb8c..293063b864 100644
--- a/apps/kimi-web/src/i18n/locales/en/sidebar.ts
+++ b/apps/kimi-web/src/i18n/locales/en/sidebar.ts
@@ -11,6 +11,9 @@ export default {
   options: 'Options',
   rename: 'Rename',
   copyPath: 'Copy path',
+  copySessionId: 'Copy session ID ⧉',
+  copied: 'Copied ✓',
+  copyFailed: 'Copy failed',
   archive: 'Archive',
   fork: 'Fork session',
   delete: 'Delete',
diff --git a/apps/kimi-web/src/i18n/locales/zh/sidebar.ts b/apps/kimi-web/src/i18n/locales/zh/sidebar.ts
index 3606d3a73e..546a9a7685 100644
--- a/apps/kimi-web/src/i18n/locales/zh/sidebar.ts
+++ b/apps/kimi-web/src/i18n/locales/zh/sidebar.ts
@@ -11,6 +11,9 @@ export default {
   options: '选项',
   rename: '重命名',
   copyPath: '复制路径',
+  copySessionId: '复制 Session ID ⧉',
+  copied: '已复制 ✓',
+  copyFailed: '复制失败',
   archive: '归档',
   fork: '分叉会话',
   delete: '删除',
diff --git a/apps/kimi-web/src/lib/clipboard.ts b/apps/kimi-web/src/lib/clipboard.ts
new file mode 100644
index 0000000000..832d9c445d
--- /dev/null
+++ b/apps/kimi-web/src/lib/clipboard.ts
@@ -0,0 +1,59 @@
+// apps/kimi-web/src/lib/clipboard.ts
+// Robust clipboard helper.
+//
+// The modern `navigator.clipboard` API is only exposed in secure contexts
+// (HTTPS / localhost / file://). When the web UI is served over plain HTTP —
+// a common remote-access setup for the server + browser topology —
+// `navigator.clipboard` is `undefined`, and a naive `navigator.clipboard
+// .writeText(...)` call throws synchronously *before* any promise is created,
+// so a `.then().catch()` chain cannot recover. We therefore probe for the API
+// first and fall back to a temporary <textarea> + `document.execCommand`.
+
+/**
+ * Copy `text` to the system clipboard.
+ *
+ * Resolves to `true` when the copy succeeded and `false` otherwise. Never
+ * rejects, so callers can safely `await` it without a try/catch.
+ */
+export async function copyTextToClipboard(text: string): Promise<boolean> {
+  // Preferred path: the async Clipboard API (secure contexts only).
+  const clipboard = typeof navigator !== 'undefined' ? navigator.clipboard : undefined;
+  if (clipboard && typeof clipboard.writeText === 'function') {
+    try {
+      await clipboard.writeText(text);
+      return true;
+    } catch {
+      // Fall through to the legacy path below (e.g. permission denied).
+    }
+  }
+
+  return legacyCopy(text);
+}
+
+function legacyCopy(text: string): boolean {
+  if (typeof document === 'undefined' || typeof document.execCommand !== 'function') {
+    return false;
+  }
+
+  const textarea = document.createElement('textarea');
+  textarea.value = text;
+  // Keep it off-screen and non-interactive so it doesn't affect layout or scroll.
+  textarea.setAttribute('readonly', '');
+  textarea.style.position = 'fixed';
+  textarea.style.top = '-9999px';
+  textarea.style.left = '-9999px';
+  textarea.style.opacity = '0';
+  document.body.appendChild(textarea);
+
+  let ok = false;
+  try {
+    textarea.focus();
+    textarea.select();
+    ok = document.execCommand('copy');
+  } catch {
+    ok = false;
+  } finally {
+    document.body.removeChild(textarea);
+  }
+  return ok;
+}
diff --git a/apps/kimi-web/test/clipboard.test.ts b/apps/kimi-web/test/clipboard.test.ts
new file mode 100644
index 0000000000..19a9397e74
--- /dev/null
+++ b/apps/kimi-web/test/clipboard.test.ts
@@ -0,0 +1,80 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { copyTextToClipboard } from '../src/lib/clipboard';
+
+// The web test suite runs in the default node environment (no jsdom), so we
+// mock the tiny `navigator` / `document` surface that the helper touches.
+
+interface FakeDocument {
+  execCommand: ReturnType<typeof vi.fn>;
+  createElement: ReturnType<typeof vi.fn>;
+  body: { appendChild: ReturnType<typeof vi.fn>; removeChild: ReturnType<typeof vi.fn> };
+  textarea: { value: string; setAttribute: ReturnType<typeof vi.fn>; focus: ReturnType<typeof vi.fn>; select: ReturnType<typeof vi.fn> };
+}
+
+function installDocument(execResult: boolean | Error): FakeDocument {
+  const textarea = {
+    value: '',
+    style: {} as Record<string, string>,
+    setAttribute: vi.fn(),
+    focus: vi.fn(),
+    select: vi.fn(),
+  };
+  const doc: FakeDocument = {
+    execCommand: vi.fn().mockImplementation(() => {
+      if (execResult instanceof Error) throw execResult;
+      return execResult;
+    }),
+    createElement: vi.fn().mockReturnValue(textarea),
+    body: { appendChild: vi.fn(), removeChild: vi.fn() },
+    textarea: textarea as FakeDocument['textarea'],
+  };
+  vi.stubGlobal('document', doc);
+  return doc;
+}
+
+function installNavigator(clipboard: unknown): void {
+  vi.stubGlobal('navigator', clipboard === undefined ? {} : { clipboard });
+}
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+});
+
+describe('copyTextToClipboard', () => {
+  it('uses navigator.clipboard when available', async () => {
+    const writeText = vi.fn().mockResolvedValue(undefined);
+    installNavigator({ writeText });
+
+    await expect(copyTextToClipboard('hello')).resolves.toBe(true);
+    expect(writeText).toHaveBeenCalledWith('hello');
+  });
+
+  it('falls back to execCommand when navigator.clipboard is undefined', async () => {
+    // Simulates an insecure (plain HTTP) context.
+    installNavigator(undefined);
+    const doc = installDocument(true);
+
+    await expect(copyTextToClipboard('abc')).resolves.toBe(true);
+    expect(doc.execCommand).toHaveBeenCalledWith('copy');
+    expect(doc.textarea.value).toBe('abc');
+    expect(doc.body.appendChild).toHaveBeenCalledTimes(1);
+    expect(doc.body.removeChild).toHaveBeenCalledTimes(1);
+  });
+
+  it('falls back to execCommand when writeText rejects', async () => {
+    const writeText = vi.fn().mockRejectedValue(new Error('denied'));
+    installNavigator({ writeText });
+    const doc = installDocument(true);
+
+    await expect(copyTextToClipboard('retry')).resolves.toBe(true);
+    expect(writeText).toHaveBeenCalled();
+    expect(doc.execCommand).toHaveBeenCalledWith('copy');
+  });
+
+  it('resolves false when both paths fail', async () => {
+    installNavigator(undefined);
+    installDocument(false);
+
+    await expect(copyTextToClipboard('nope')).resolves.toBe(false);
+  });
+});