diff --git a/electron/harness/agent-loop/engine.ts b/electron/harness/agent-loop/engine.ts
index d98d721..2e0f356 100644
--- a/electron/harness/agent-loop/engine.ts
+++ b/electron/harness/agent-loop/engine.ts
@@ -400,8 +400,10 @@ export class AgentLoopEngine extends EventEmitter {
       await this.transitionTo(AgentLoopState.OBSERVING);
 
       // === 上下文压缩（基于 token 使用率触发） ===
+      // 有效上下文窗口：Ollama 使用 contextLength (numCtx)，其他 Provider 使用 contextWindow
+      const effectiveContextWindow = this.config.contextLength ?? this.config.contextWindow;
       const estimatedTokens = this.estimateMessagesTokens(request.messages);
-      const compressionThreshold = this.config.compressionThreshold * this.config.contextWindow;
+      const compressionThreshold = this.config.compressionThreshold * effectiveContextWindow;
       if (estimatedTokens > compressionThreshold && request.messages.length > 10) {
         await this.transitionTo(AgentLoopState.COMPRESSING);
         const compressed = await this.compressMessages(request.messages);
@@ -537,10 +539,10 @@ export class AgentLoopEngine extends EventEmitter {
     const toKeep = messages.slice(messages.length - keepRecent);
 
     // 构建摘要请求
+    // 不截断单条消息——摘要请求是独立 API 调用，不共享主对话上下文窗口
     const conversationText = toCompress.map((m) => {
       const role = m.role.toUpperCase();
-      const content = m.content.slice(0, 500); // 每条消息最多 500 字符
-      return `[${role}] ${content}`;
+      return `[${role}] ${m.content}`;
     }).join('\n\n');
 
     const summaryRequest: MetonaRequest = {
diff --git a/electron/harness/tools/built-in/delegate-task.ts b/electron/harness/tools/built-in/delegate-task.ts
index 078371c..6303bb5 100644
--- a/electron/harness/tools/built-in/delegate-task.ts
+++ b/electron/harness/tools/built-in/delegate-task.ts
@@ -25,7 +25,7 @@ export class DelegateTaskTool implements IMetonaTool {
         },
         tools: {
           type: 'array',
-          items: { type: 'string' },
+          items: { type: 'string', description: 'Tool name' },
           description: 'Optional whitelist of tool names the SubAgent can use (e.g. ["read_file", "web_search"]). If omitted, SubAgent inherits all tools.',
         },
         maxIterations: {
diff --git a/electron/main.ts b/electron/main.ts
index 8547402..5788589 100644
--- a/electron/main.ts
+++ b/electron/main.ts
@@ -232,6 +232,14 @@ async function initialize(): Promise<void> {
   const reloadAdapter = () => {
     const newAdapter = createAdapter();
     agentLoop.setAdapter(newAdapter);
+    // Provider 切换时同步 contextLength：仅 Ollama 使用 numCtx 作为有效上下文窗口
+    const provider = configService.get<string>('llm.provider') ?? '';
+    if (provider === 'ollama') {
+      const numCtx = configService.get<number>('ollama.numCtx');
+      agentLoop.updateConfig({ contextLength: numCtx ?? undefined });
+    } else {
+      agentLoop.updateConfig({ contextLength: undefined });
+    }
   };
 
   // ===== 窗口管理 =====