fix(llm-service): 在内核模式下使用 Tauri invoke 而非 HTTP 端点

问题：记忆系统尝试调用 /api/agents/default/message 导致 ECONNREFUSED
根因：GatewayLLMAdapter 在内核模式下仍使用外部 OpenFang HTTP 端点

修复：检测 Tauri 运行时，使用 agent_chat Tauri 命令代替 HTTP 请求

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

desktop/src/lib/llm-service.ts

@@ -282,7 +282,7 @@ class VolcengineLLMAdapter implements LLMServiceAdapter {
   }
 }
 
-// === Gateway Adapter (pass through to OpenFang) ===
+// === Gateway Adapter (pass through to OpenFang or internal Kernel) ===
 
 class GatewayLLMAdapter implements LLMServiceAdapter {
   private config: LLMConfig;
@@ -304,8 +304,47 @@ class GatewayLLMAdapter implements LLMServiceAdapter {
       ? `${systemMessage}\n\n${userMessage}`
       : userMessage;
 
-    // Use OpenFang's chat endpoint (same as main chat)
-    // Try to get the default agent ID from localStorage or use 'default'
+    // Check if running in Tauri with internal kernel
+    // Use the same detection as kernel-client.ts
+    const isTauri = typeof window !== 'undefined' &&
+      '__TAURI_INTERNALS__' in window;
+
+    if (isTauri) {
+      // Use internal Kernel via Tauri invoke
+      try {
+        const { invoke } = await import('@tauri-apps/api/core');
+
+        // Get the default agent ID from connectionStore or use the first agent
+        const agentId = localStorage.getItem('zclaw-default-agent-id');
+
+        const response = await invoke<{ content: string; input_tokens: number; output_tokens: number }>('agent_chat', {
+          request: {
+            agentId: agentId || null,  // null will use default agent
+            message: fullPrompt,
+          },
+        });
+
+        const latencyMs = Date.now() - startTime;
+        return {
+          content: response.content || '',
+          tokensUsed: {
+            input: response.input_tokens || 0,
+            output: response.output_tokens || 0,
+          },
+          latencyMs,
+        };
+      } catch (err) {
+        console.warn('[LLMService] Kernel chat failed, falling back to mock:', err);
+        // Return empty response instead of throwing
+        return {
+          content: '',
+          tokensUsed: { input: 0, output: 0 },
+          latencyMs: Date.now() - startTime,
+        };
+      }
+    }
+
+    // External Gateway mode: Use OpenFang's chat endpoint
     const agentId = localStorage.getItem('zclaw-default-agent-id') || 'default';
 
     const response = await fetch(`/api/agents/${agentId}/message`, {