config: add prefer_native and NativeSearchCapable for model-native search

config/config.example.json

@@ -313,6 +313,7 @@
     "allow_write_paths": null,
     "web": {
       "enabled": true,
+      "prefer_native": true,
       "brave": {
         "enabled": false,
         "api_key": "YOUR_BRAVE_API_KEY",

pkg/config/config.go

@@ -690,6 +690,12 @@ type WebToolsConfig struct {
 	Perplexity PerplexityConfig `                                json:"perplexity"`
 	SearXNG    SearXNGConfig    `                                json:"searxng"`
 	GLMSearch  GLMSearchConfig  `                                json:"glm_search"`
+	// PreferNative controls whether to use provider-native web search when
+	// the active LLM supports it (e.g. OpenAI web_search_preview). When true,
+	// the client-side web_search tool is hidden to avoid duplicate search surfaces,
+	// and the provider's built-in search is used instead. Falls back to client-side
+	// search when the provider does not support native search.
+	PreferNative bool `json:"prefer_native" env:"PICOCLAW_TOOLS_WEB_PREFER_NATIVE"`
 	// Proxy is an optional proxy URL for web tools (http/https/socks5/socks5h).
 	// For authenticated proxies, prefer HTTP_PROXY/HTTPS_PROXY env vars instead of embedding credentials in config.
 	Proxy           string `json:"proxy,omitempty"             env:"PICOCLAW_TOOLS_WEB_PROXY"`

pkg/config/defaults.go

@@ -410,6 +410,7 @@ func DefaultConfig() *Config {
 				ToolConfig: ToolConfig{
 					Enabled: true,
 				},
+				PreferNative:    true,
 				Proxy:           "",
 				FetchLimitBytes: 10 * 1024 * 1024, // 10MB by default
 				Brave: BraveConfig{

pkg/providers/types.go

@@ -44,6 +44,15 @@ type ThinkingCapable interface {
 	SupportsThinking() bool
 }
 
+// NativeSearchCapable is an optional interface for providers that support
+// built-in web search during LLM inference (e.g. OpenAI web_search_preview,
+// xAI Grok search). When the active provider implements this interface and
+// returns true, the agent loop can hide the client-side web_search tool to
+// avoid duplicate search surfaces and use the provider's native search instead.
+type NativeSearchCapable interface {
+	SupportsNativeSearch() bool
+}
+
 // FailoverReason classifies why an LLM request failed for fallback decisions.
 type FailoverReason string