feat(vscode-ide-companion): 新增自动完成功能

- 新增 CompletionMenu 组件支持 @ 和 / 触发补全
- 新增 useCompletionTrigger hook 处理补全触发逻辑
- 支持实时查询和过滤补全项

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/vscode-ide-companion/src/webview/hooks/useCompletionTrigger.ts

@@ -0,0 +1,176 @@
+/**
+ * @license
+ * Copyright 2025 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import type { RefObject } from 'react';
+import { useState, useEffect, useCallback } from 'react';
+import type { CompletionItem } from '../components/CompletionMenu.js';
+
+interface CompletionTriggerState {
+  isOpen: boolean;
+  triggerChar: '@' | '/' | null;
+  query: string;
+  position: { top: number; left: number };
+  items: CompletionItem[];
+}
+
+/**
+ * Hook to handle @ and / completion triggers in contentEditable
+ * Based on vscode-copilot-chat's AttachContextAction
+ */
+export function useCompletionTrigger(
+  inputRef: RefObject<HTMLDivElement>,
+  getCompletionItems: (
+    trigger: '@' | '/',
+    query: string,
+  ) => Promise<CompletionItem[]>,
+) {
+  const [state, setState] = useState<CompletionTriggerState>({
+    isOpen: false,
+    triggerChar: null,
+    query: '',
+    position: { top: 0, left: 0 },
+    items: [],
+  });
+
+  const closeCompletion = useCallback(() => {
+    setState({
+      isOpen: false,
+      triggerChar: null,
+      query: '',
+      position: { top: 0, left: 0 },
+      items: [],
+    });
+  }, []);
+
+  const openCompletion = useCallback(
+    async (
+      trigger: '@' | '/',
+      query: string,
+      position: { top: number; left: number },
+    ) => {
+      const items = await getCompletionItems(trigger, query);
+      setState({
+        isOpen: true,
+        triggerChar: trigger,
+        query,
+        position,
+        items,
+      });
+    },
+    [getCompletionItems],
+  );
+
+  useEffect(() => {
+    const inputElement = inputRef.current;
+    if (!inputElement) {
+      return;
+    }
+
+    const getCursorPosition = (): { top: number; left: number } | null => {
+      const selection = window.getSelection();
+      if (!selection || selection.rangeCount === 0) {
+        return null;
+      }
+
+      try {
+        const range = selection.getRangeAt(0);
+        const rect = range.getBoundingClientRect();
+
+        // If the range has a valid position, use it
+        if (rect.top > 0 && rect.left > 0) {
+          return {
+            top: rect.top,
+            left: rect.left,
+          };
+        }
+
+        // Fallback: use input element's position
+        const inputRect = inputElement.getBoundingClientRect();
+        return {
+          top: inputRect.top,
+          left: inputRect.left,
+        };
+      } catch (error) {
+        console.error(
+          '[useCompletionTrigger] Error getting cursor position:',
+          error,
+        );
+        const inputRect = inputElement.getBoundingClientRect();
+        return {
+          top: inputRect.top,
+          left: inputRect.left,
+        };
+      }
+    };
+
+    const handleInput = async () => {
+      const text = inputElement.textContent || '';
+      const selection = window.getSelection();
+      if (!selection || selection.rangeCount === 0) {
+        return;
+      }
+
+      const range = selection.getRangeAt(0);
+      const cursorPosition = range.startOffset;
+
+      // Find trigger character before cursor
+      const textBeforeCursor = text.substring(0, cursorPosition);
+      const lastAtMatch = textBeforeCursor.lastIndexOf('@');
+      const lastSlashMatch = textBeforeCursor.lastIndexOf('/');
+
+      // Check if we're in a trigger context
+      let triggerPos = -1;
+      let triggerChar: '@' | '/' | null = null;
+
+      if (lastAtMatch > lastSlashMatch) {
+        triggerPos = lastAtMatch;
+        triggerChar = '@';
+      } else if (lastSlashMatch > lastAtMatch) {
+        triggerPos = lastSlashMatch;
+        triggerChar = '/';
+      }
+
+      // Check if trigger is at word boundary (start of line or after space)
+      if (triggerPos >= 0 && triggerChar) {
+        const charBefore = triggerPos > 0 ? text[triggerPos - 1] : ' ';
+        const isValidTrigger =
+          charBefore === ' ' || charBefore === '\n' || triggerPos === 0;
+
+        if (isValidTrigger) {
+          const query = text.substring(triggerPos + 1, cursorPosition);
+
+          // Only show if query doesn't contain spaces (still typing the reference)
+          if (!query.includes(' ') && !query.includes('\n')) {
+            // Get precise cursor position for menu
+            const cursorPos = getCursorPosition();
+            if (cursorPos) {
+              await openCompletion(triggerChar, query, cursorPos);
+              return;
+            }
+          }
+        }
+      }
+
+      // Close if no valid trigger
+      if (state.isOpen) {
+        closeCompletion();
+      }
+    };
+
+    inputElement.addEventListener('input', handleInput);
+    return () => inputElement.removeEventListener('input', handleInput);
+  }, [inputRef, state.isOpen, openCompletion, closeCompletion]);
+
+  return {
+    isOpen: state.isOpen,
+    triggerChar: state.triggerChar,
+    query: state.query,
+    position: state.position,
+    items: state.items,
+    closeCompletion,
+    openCompletion,
+  };
+}