fix: 记忆去重时明确告知 AI「已存在，不要再重复添加」

之前 addEntry 检测到重复后静默返回已有条目(success)，AI 误以为又成功保存了
新条目，于是继续循环调用。现在改为抛出 DuplicateEntryError，tool handler
捕获后返回 {success:true, duplicate:true, message:'已跳过...不要再重复添加'}，
明确告诉 AI 任务已完成。

也处理了内存面板的手动添加场景，友好提示用户。

src/renderer/components/memory-modal.ts

@@ -3,7 +3,7 @@
  * 基于工作空间 MEMORY.md 文件
  */
 
-import { loadAllEntries, addEntry, removeEntry, type MemoryEntry, type MemoryType } from '../services/memory-service.js';
+import { loadAllEntries, addEntry, removeEntry, DuplicateEntryError, type MemoryEntry, type MemoryType } from '../services/memory-service.js';
 import { showToast } from './toast.js';
 import { showPrompt, showConfirm } from './prompt-modal.js';
 import { escapeHtml, formatTime } from '../utils/utils.js';
@@ -170,6 +170,10 @@ async function openAddDialog(): Promise<void> {
     await renderList();
     showToast('记忆已添加', 'success', 1500);
   } catch (err) {
+    if (err instanceof DuplicateEntryError) {
+      showToast('该记忆已存在，无需重复添加', 'info', 2000);
+    } else {
       showToast(`添加失败: ${(err as Error).message}`, 'error');
     }
+  }
 }

src/renderer/services/memory-service.ts

@@ -21,6 +21,18 @@ import { logInfo, logWarn, logDebug, logMemory } from './log-service.js';
 // 类型定义
 // ═══════════════════════════════════════════════════════════════
 
+/** 重复条目错误：记忆已存在时抛出，告诉调用方无需重复添加 */
+export class DuplicateEntryError extends Error {
+  existingId: string;
+  existingPreview: string;
+  constructor(id: string, preview: string) {
+    super(`重复条目: ${preview}... (ID: ${id})`);
+    this.name = 'DuplicateEntryError';
+    this.existingId = id;
+    this.existingPreview = preview;
+  }
+}
+
 export type MemoryType = 'fact' | 'preference' | 'rule';
 
 export interface MemoryEntry {
@@ -435,7 +447,10 @@ export async function addEntry(
     if (prefixLen > 20 && content.slice(0, prefixLen) === e.content.slice(0, prefixLen)) return true;
     return simpleSimilarity(e.content, content) > 0.8;
   });
-  if (existing) return existing;
+  if (existing) {
+    logDebug('记忆去重: 已有相同条目', `${type}: ${content.slice(0, 40)}`);
+    throw new DuplicateEntryError(existing.id, existing.content.slice(0, 60));
+  }
 
   const entry: MemoryEntry = {
     id: generateMemoryId(),

src/renderer/services/tool-registry.ts

@@ -779,7 +779,7 @@ export async function executeTool(toolName: string, args: Record<string, unknown
   try {
     // 内存工具（不走 IPC，直接处理 MEMORY.md）
     if (toolName === 'memory') {
-      const { search, addEntry, replaceEntry, removeEntry, loadAllEntries } = await import('./memory-service.js');
+      const { search, addEntry, replaceEntry, removeEntry, loadAllEntries, DuplicateEntryError } = await import('./memory-service.js');
       const action = args.action as string;
       switch (action) {
         case 'search': {
@@ -796,9 +796,17 @@ export async function executeTool(toolName: string, args: Record<string, unknown
           const importance = (args.importance as number) || 5;
           const tags = (args.tags as string[]) || [];
           if (!content || content.length < 2) return { success: false, error: 'add 操作缺少 content 参数或内容太短。示例: {"action":"add","type":"fact","content":"具体的记忆内容"}' };
+          try {
             const entry = await addEntry(type, content, importance, tags);
             logToolResult('memory', true, `${type}: ${content.slice(0, 50)}`);
             return { success: true, action, id: entry.id, type: entry.type, content: entry.content };
+          } catch (err) {
+            if (err instanceof DuplicateEntryError) {
+              logToolResult('memory', true, `重复跳过: ${(err as DuplicateEntryError).existingPreview}`);
+              return { success: true, action, duplicate: true, existing_id: (err as DuplicateEntryError).existingId, message: `已跳过: 相同内容的记忆已存在 (${(err as DuplicateEntryError).existingPreview})。不要再重复添加，任务已完成。` };
+            }
+            throw err;
+          }
         }
         case 'replace': {
           const oldText = String(args.old_text || '');