diff --git a/.changeset/web-extract-mention-menu.md b/.changeset/web-extract-mention-menu.md
new file mode 100644
index 0000000000..8217f84f07
--- /dev/null
+++ b/.changeset/web-extract-mention-menu.md
@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Extract the composer's @-mention menu logic into a reusable composable.
diff --git a/apps/kimi-web/src/components/Composer.vue b/apps/kimi-web/src/components/Composer.vue
index fa3bf080f3..02c919898b 100644
--- a/apps/kimi-web/src/components/Composer.vue
+++ b/apps/kimi-web/src/components/Composer.vue
@@ -12,6 +12,7 @@ import { modelThinkingAvailability } from '../lib/modelThinking';
 import { draftStorageKey, safeGetString, safeRemove, safeSetString } from '../lib/storage';
 import { useInputHistory } from '../composables/useInputHistory';
 import { useSlashMenu } from '../composables/useSlashMenu';
+import { useMentionMenu } from '../composables/useMentionMenu';
 
 // ---------------------------------------------------------------------------
 // Attachment state
@@ -170,72 +171,23 @@ const {
 });
 
 // ---------------------------------------------------------------------------
-// @-mention menu
+// @-mention menu — see useMentionMenu for the implementation. The composer
+// keeps the keydown orchestration because it also juggles the slash menu and
+// history recall.
 // ---------------------------------------------------------------------------
-
-const mentionOpen = ref(false);
-const mentionItems = ref<FileItem[]>([]);
-const mentionActive = ref(0);
-const mentionLoading = ref(false);
-
-// Debounce timer for mention search
-let mentionTimer: ReturnType<typeof setTimeout> | null = null;
-
-/** Find the @token under the cursor in the current text value. Returns null if none. */
-function getMentionToken(): { token: string; start: number; end: number } | null {
-  const val = text.value;
-  const pos = textareaRef.value?.selectionStart ?? val.length;
-  // Walk backwards from cursor to find the start of a @token
-  let start = pos - 1;
-  while (start >= 0 && !/\s/.test(val[start]!)) {
-    start--;
-  }
-  start++;
-  const tokenPart = val.slice(start, pos);
-  if (!tokenPart.startsWith('@')) return null;
-  // The end of the token is where the cursor is (or after the next space)
-  return { token: tokenPart.slice(1), start, end: pos };
-}
-
-function updateMentionMenu(): void {
-  const mt = getMentionToken();
-  if (!mt || !props.searchFiles) {
-    mentionOpen.value = false;
-    return;
-  }
-  const query = mt.token;
-  if (mentionTimer !== null) clearTimeout(mentionTimer);
-  mentionTimer = setTimeout(async () => {
-    mentionLoading.value = true;
-    mentionOpen.value = true;
-    mentionActive.value = 0;
-    try {
-      const results = await props.searchFiles!(query);
-      mentionItems.value = results;
-    } catch {
-      mentionItems.value = [];
-    } finally {
-      mentionLoading.value = false;
-    }
-  }, 200);
-}
-
-function selectMentionItem(item: FileItem): void {
-  const mt = getMentionToken();
-  if (!mt) return;
-  const val = text.value;
-  // Replace @query token with the file path
-  text.value = val.slice(0, mt.start) + item.path + val.slice(mt.end);
-  mentionOpen.value = false;
-  void nextTick(() => {
-    const el = textareaRef.value;
-    if (!el) return;
-    const newPos = mt.start + item.path.length;
-    el.setSelectionRange(newPos, newPos);
-    el.focus();
-    autosize();
-  });
-}
+const {
+  open: mentionOpen,
+  items: mentionItems,
+  active: mentionActive,
+  loading: mentionLoading,
+  update: updateMentionMenu,
+  select: selectMentionItem,
+} = useMentionMenu({
+  text,
+  textareaRef,
+  autosize,
+  searchFiles: () => props.searchFiles,
+});
 
 // ---------------------------------------------------------------------------
 // Input event handler — updates both menus
diff --git a/apps/kimi-web/src/components/MentionMenu.vue b/apps/kimi-web/src/components/MentionMenu.vue
index d6373076bb..c00943c43f 100644
--- a/apps/kimi-web/src/components/MentionMenu.vue
+++ b/apps/kimi-web/src/components/MentionMenu.vue
@@ -2,11 +2,11 @@
 <!-- Popup list of file paths shown when user types @ in the Composer textarea. -->
 <script setup lang="ts">
 import { useI18n } from 'vue-i18n';
+import type { FileItem } from '../types';
 
-export interface FileItem {
-  path: string;
-  name: string;
-}
+// Re-exported for the .vue consumers (Composer / ChatDock / ConversationPane)
+// that import FileItem from this component.
+export type { FileItem };
 
 const props = defineProps<{
   items: FileItem[];
diff --git a/apps/kimi-web/src/composables/useMentionMenu.ts b/apps/kimi-web/src/composables/useMentionMenu.ts
new file mode 100644
index 0000000000..e8b71828e9
--- /dev/null
+++ b/apps/kimi-web/src/composables/useMentionMenu.ts
@@ -0,0 +1,98 @@
+// apps/kimi-web/src/composables/useMentionMenu.ts
+import { nextTick, ref, type Ref } from 'vue';
+import type { FileItem } from '../types';
+
+export interface MentionMenuDeps {
+  /** The live composer text — the @token is read from it and rewritten on select. */
+  text: Ref<string>;
+  /** The textarea element, used to read the caret and place it after insertion. */
+  textareaRef: Ref<HTMLTextAreaElement | null>;
+  /** Re-fit the textarea after its text changes. */
+  autosize: () => void;
+  /** File search for the @-query (getter; undefined disables the menu). */
+  searchFiles: () => ((q: string) => Promise<FileItem[]>) | undefined;
+}
+
+interface MentionToken {
+  token: string;
+  start: number;
+  end: number;
+}
+
+/**
+ * `@` file-mention menu: token detection, debounced search, keyboard navigation
+ * state, and insertion.
+ *
+ * The composer keeps the keydown orchestration (arrow keys, Enter/Tab, Escape)
+ * because it also juggles the slash menu and history recall; this composable
+ * owns the menu's open/items/active/loading state and the search/insert logic.
+ */
+export function useMentionMenu(deps: MentionMenuDeps) {
+  const { text, textareaRef, autosize, searchFiles } = deps;
+
+  const open = ref(false);
+  const items = ref<FileItem[]>([]);
+  const active = ref(0);
+  const loading = ref(false);
+
+  // Debounce timer for the search.
+  let timer: ReturnType<typeof setTimeout> | null = null;
+
+  /** Find the @token under the cursor in the current text value. Returns null if none. */
+  function getMentionToken(): MentionToken | null {
+    const val = text.value;
+    const pos = textareaRef.value?.selectionStart ?? val.length;
+    // Walk backwards from the cursor to find the start of a @token.
+    let start = pos - 1;
+    while (start >= 0 && !/\s/.test(val[start]!)) {
+      start--;
+    }
+    start++;
+    const tokenPart = val.slice(start, pos);
+    if (!tokenPart.startsWith('@')) return null;
+    // The end of the token is where the cursor is (or after the next space).
+    return { token: tokenPart.slice(1), start, end: pos };
+  }
+
+  function update(): void {
+    const mt = getMentionToken();
+    const search = searchFiles();
+    if (!mt || !search) {
+      open.value = false;
+      return;
+    }
+    const query = mt.token;
+    if (timer !== null) clearTimeout(timer);
+    timer = setTimeout(async () => {
+      loading.value = true;
+      open.value = true;
+      active.value = 0;
+      try {
+        items.value = await search(query);
+      } catch {
+        items.value = [];
+      } finally {
+        loading.value = false;
+      }
+    }, 200);
+  }
+
+  function select(item: FileItem): void {
+    const mt = getMentionToken();
+    if (!mt) return;
+    const val = text.value;
+    // Replace the @query token with the file path.
+    text.value = val.slice(0, mt.start) + item.path + val.slice(mt.end);
+    open.value = false;
+    void nextTick(() => {
+      const el = textareaRef.value;
+      if (!el) return;
+      const newPos = mt.start + item.path.length;
+      el.setSelectionRange(newPos, newPos);
+      el.focus();
+      autosize();
+    });
+  }
+
+  return { open, items, active, loading, update, select };
+}
diff --git a/apps/kimi-web/src/types.ts b/apps/kimi-web/src/types.ts
index 9418d19096..aeaafc3ee3 100644
--- a/apps/kimi-web/src/types.ts
+++ b/apps/kimi-web/src/types.ts
@@ -18,6 +18,12 @@ export interface FileData {
   lineCount?: number;
 }
 
+/** A file entry shown in the composer's @-mention menu. */
+export interface FileItem {
+  path: string;
+  name: string;
+}
+
 export interface Session {
   id: string;
   title: string;
diff --git a/apps/kimi-web/test/mention-menu.test.ts b/apps/kimi-web/test/mention-menu.test.ts
new file mode 100644
index 0000000000..13006bca44
--- /dev/null
+++ b/apps/kimi-web/test/mention-menu.test.ts
@@ -0,0 +1,97 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { nextTick, ref, type Ref } from 'vue';
+import { useMentionMenu } from '../src/composables/useMentionMenu';
+import type { FileItem } from '../src/types';
+
+interface MockTextarea {
+  value: string;
+  selectionStart: number;
+  setSelectionRange: (start: number, end: number) => void;
+  focus: () => void;
+}
+
+function setup(initialText = '', searchFiles?: (q: string) => Promise<FileItem[]>) {
+  const textarea: MockTextarea = {
+    value: initialText,
+    // Caret defaults to the end of the text.
+    selectionStart: initialText.length,
+    setSelectionRange(start: number) {
+      this.selectionStart = start;
+    },
+    focus: () => {},
+  };
+  const text = ref(initialText);
+  const textareaRef = ref(textarea as unknown as HTMLTextAreaElement) as Ref<HTMLTextAreaElement | null>;
+  const mention = useMentionMenu({
+    text,
+    textareaRef,
+    autosize: () => {},
+    searchFiles: () => searchFiles,
+  });
+  return { text, textarea, mention };
+}
+
+describe('useMentionMenu — update', () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it('stays closed when there is no @token', async () => {
+    const searchFiles = vi.fn().mockResolvedValue([]);
+    const { mention } = setup('hello', searchFiles);
+    mention.update();
+    await vi.advanceTimersByTimeAsync(200);
+    expect(mention.open.value).toBe(false);
+    expect(searchFiles).not.toHaveBeenCalled();
+  });
+
+  it('stays closed when searchFiles is not provided', async () => {
+    const { mention } = setup('@a');
+    mention.update();
+    await vi.advanceTimersByTimeAsync(200);
+    expect(mention.open.value).toBe(false);
+  });
+
+  it('opens with search results after the debounce', async () => {
+    const searchFiles = vi.fn().mockResolvedValue([{ path: 'src/a.ts', name: 'a.ts' }]);
+    const { mention } = setup('@a', searchFiles);
+    mention.update();
+    expect(mention.open.value).toBe(false); // debounced, not yet
+    await vi.advanceTimersByTimeAsync(200);
+    expect(searchFiles).toHaveBeenCalledWith('a');
+    expect(mention.open.value).toBe(true);
+    expect(mention.items.value).toEqual([{ path: 'src/a.ts', name: 'a.ts' }]);
+    expect(mention.loading.value).toBe(false);
+    expect(mention.active.value).toBe(0);
+  });
+
+  it('clears items and stops loading when the search throws', async () => {
+    const searchFiles = vi.fn().mockRejectedValue(new Error('boom'));
+    const { mention } = setup('@a', searchFiles);
+    mention.update();
+    await vi.advanceTimersByTimeAsync(200);
+    expect(mention.items.value).toEqual([]);
+    expect(mention.loading.value).toBe(false);
+  });
+});
+
+describe('useMentionMenu — select', () => {
+  it('replaces the @token with the chosen path', async () => {
+    const { text, textarea, mention } = setup('hello @a');
+    textarea.value = 'hello @a';
+    mention.select({ path: 'src/a.ts', name: 'a.ts' });
+    expect(text.value).toBe('hello src/a.ts');
+    expect(mention.open.value).toBe(false);
+    await nextTick();
+  });
+
+  it('is a no-op when there is no @token', () => {
+    const { text, mention } = setup('hello');
+    mention.select({ path: 'src/a.ts', name: 'a.ts' });
+    expect(text.value).toBe('hello');
+  });
+});