feat(security): disable exec, i2c, spi tools by default

Security hardening: exec, I2C, SPI tools are now disabled by default
and require explicit opt-in via config or environment variables.
Users who need these tools must set enabled: true in config.json
or use PICOCLAW_TOOLS_{EXEC,I2C,SPI}_ENABLED=true.

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

config/config.example.json

@@ -114,6 +114,15 @@
     }
   },
   "tools": {
+    "exec": {
+      "enabled": false
+    },
+    "i2c": {
+      "enabled": false
+    },
+    "spi": {
+      "enabled": false
+    },
     "web": {
       "search": {
         "api_key": "YOUR_BRAVE_API_KEY",

pkg/agent/loop.go

@@ -70,8 +70,10 @@ func createToolRegistry(workspace string, restrict bool, cfg *config.Config, msg
 	registry.Register(tools.NewEditFileTool(workspace, restrict))
 	registry.Register(tools.NewAppendFileTool(workspace, restrict))
 
-	// Shell execution
+	// Shell execution (disabled by default for security)
+	if cfg.Tools.Exec.Enabled {
 		registry.Register(tools.NewExecTool(workspace, restrict))
+	}
 
 	if searchTool := tools.NewWebSearchTool(tools.WebSearchToolOptions{
 		BraveAPIKey:          cfg.Tools.Web.Brave.APIKey,
@@ -84,9 +86,13 @@ func createToolRegistry(workspace string, restrict bool, cfg *config.Config, msg
 	}
 	registry.Register(tools.NewWebFetchTool(50000))
 
-	// Hardware tools (I2C, SPI) - Linux only, returns error on other platforms
+	// Hardware tools (I2C, SPI) - disabled by default for security
+	if cfg.Tools.I2C.Enabled {
 		registry.Register(tools.NewI2CTool())
+	}
+	if cfg.Tools.SPI.Enabled {
 		registry.Register(tools.NewSPITool())
+	}
 
 	// Message tool - available to both agent and subagent
 	// Subagent uses it to communicate directly with user

pkg/agent/loop_test.go

@@ -323,6 +323,247 @@ func TestAgentLoop_GetStartupInfo(t *testing.T) {
 	}
 }
 
+// TestCreateToolRegistry_ExecDisabled verifies exec tool is NOT registered when disabled
+func TestCreateToolRegistry_ExecDisabled(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "agent-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				Model:             "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+		Tools: config.ToolsConfig{
+			Exec: config.ExecToolsConfig{
+				Enabled: false,
+			},
+		},
+	}
+
+	msgBus := bus.NewMessageBus()
+	provider := &mockProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	info := al.GetStartupInfo()
+	toolsInfo := info["tools"].(map[string]interface{})
+	toolsList := toolsInfo["names"].([]string)
+
+	for _, name := range toolsList {
+		if name == "exec" {
+			t.Error("exec tool should NOT be registered when Exec.Enabled is false")
+		}
+	}
+}
+
+// TestCreateToolRegistry_ExecEnabled verifies exec tool IS registered when enabled
+func TestCreateToolRegistry_ExecEnabled(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "agent-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				Model:             "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+		Tools: config.ToolsConfig{
+			Exec: config.ExecToolsConfig{
+				Enabled: true,
+			},
+		},
+	}
+
+	msgBus := bus.NewMessageBus()
+	provider := &mockProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	info := al.GetStartupInfo()
+	toolsInfo := info["tools"].(map[string]interface{})
+	toolsList := toolsInfo["names"].([]string)
+
+	found := false
+	for _, name := range toolsList {
+		if name == "exec" {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Error("exec tool should be registered when Exec.Enabled is true")
+	}
+}
+
+// TestCreateToolRegistry_I2CDisabled verifies I2C tool is NOT registered when disabled
+func TestCreateToolRegistry_I2CDisabled(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "agent-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				Model:             "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+		Tools: config.ToolsConfig{
+			I2C: config.I2CToolsConfig{Enabled: false},
+		},
+	}
+
+	msgBus := bus.NewMessageBus()
+	provider := &mockProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	info := al.GetStartupInfo()
+	toolsInfo := info["tools"].(map[string]interface{})
+	toolsList := toolsInfo["names"].([]string)
+
+	for _, name := range toolsList {
+		if name == "i2c" {
+			t.Error("i2c tool should NOT be registered when I2C.Enabled is false")
+		}
+	}
+}
+
+// TestCreateToolRegistry_I2CEnabled verifies I2C tool IS registered when enabled
+func TestCreateToolRegistry_I2CEnabled(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "agent-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				Model:             "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+		Tools: config.ToolsConfig{
+			I2C: config.I2CToolsConfig{Enabled: true},
+		},
+	}
+
+	msgBus := bus.NewMessageBus()
+	provider := &mockProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	info := al.GetStartupInfo()
+	toolsInfo := info["tools"].(map[string]interface{})
+	toolsList := toolsInfo["names"].([]string)
+
+	found := false
+	for _, name := range toolsList {
+		if name == "i2c" {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Error("i2c tool should be registered when I2C.Enabled is true")
+	}
+}
+
+// TestCreateToolRegistry_SPIDisabled verifies SPI tool is NOT registered when disabled
+func TestCreateToolRegistry_SPIDisabled(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "agent-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				Model:             "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+		Tools: config.ToolsConfig{
+			SPI: config.SPIToolsConfig{Enabled: false},
+		},
+	}
+
+	msgBus := bus.NewMessageBus()
+	provider := &mockProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	info := al.GetStartupInfo()
+	toolsInfo := info["tools"].(map[string]interface{})
+	toolsList := toolsInfo["names"].([]string)
+
+	for _, name := range toolsList {
+		if name == "spi" {
+			t.Error("spi tool should NOT be registered when SPI.Enabled is false")
+		}
+	}
+}
+
+// TestCreateToolRegistry_SPIEnabled verifies SPI tool IS registered when enabled
+func TestCreateToolRegistry_SPIEnabled(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "agent-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				Model:             "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+		Tools: config.ToolsConfig{
+			SPI: config.SPIToolsConfig{Enabled: true},
+		},
+	}
+
+	msgBus := bus.NewMessageBus()
+	provider := &mockProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	info := al.GetStartupInfo()
+	toolsInfo := info["tools"].(map[string]interface{})
+	toolsList := toolsInfo["names"].([]string)
+
+	found := false
+	for _, name := range toolsList {
+		if name == "spi" {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Error("spi tool should be registered when SPI.Enabled is true")
+	}
+}
+
 // TestAgentLoop_Stop verifies Stop() sets running to false
 func TestAgentLoop_Stop(t *testing.T) {
 	tmpDir, err := os.MkdirTemp("", "agent-test-*")

pkg/config/config.go

@@ -211,8 +211,23 @@ type WebToolsConfig struct {
 	DuckDuckGo DuckDuckGoConfig `json:"duckduckgo"`
 }
 
+type ExecToolsConfig struct {
+	Enabled bool `json:"enabled" env:"PICOCLAW_TOOLS_EXEC_ENABLED"`
+}
+
+type I2CToolsConfig struct {
+	Enabled bool `json:"enabled" env:"PICOCLAW_TOOLS_I2C_ENABLED"`
+}
+
+type SPIToolsConfig struct {
+	Enabled bool `json:"enabled" env:"PICOCLAW_TOOLS_SPI_ENABLED"`
+}
+
 type ToolsConfig struct {
 	Web  WebToolsConfig  `json:"web"`
+	Exec ExecToolsConfig `json:"exec"`
+	I2C  I2CToolsConfig  `json:"i2c"`
+	SPI  SPIToolsConfig  `json:"spi"`
 }
 
 func DefaultConfig() *Config {
@@ -311,6 +326,15 @@ func DefaultConfig() *Config {
 			Port: 18790,
 		},
 		Tools: ToolsConfig{
+			Exec: ExecToolsConfig{
+				Enabled: false,
+			},
+			I2C: I2CToolsConfig{
+				Enabled: false,
+			},
+			SPI: SPIToolsConfig{
+				Enabled: false,
+			},
 			Web: WebToolsConfig{
 				Brave: BraveConfig{
 					Enabled:    false,

pkg/config/config_test.go

@@ -134,6 +134,30 @@ func TestDefaultConfig_Channels(t *testing.T) {
 	}
 }
 
+// TestDefaultConfig_ExecToolDisabled verifies exec tool is disabled by default
+func TestDefaultConfig_ExecToolDisabled(t *testing.T) {
+	cfg := DefaultConfig()
+	if cfg.Tools.Exec.Enabled {
+		t.Error("Exec tool should be disabled by default")
+	}
+}
+
+// TestDefaultConfig_I2CToolDisabled verifies I2C tool is disabled by default
+func TestDefaultConfig_I2CToolDisabled(t *testing.T) {
+	cfg := DefaultConfig()
+	if cfg.Tools.I2C.Enabled {
+		t.Error("I2C tool should be disabled by default")
+	}
+}
+
+// TestDefaultConfig_SPIToolDisabled verifies SPI tool is disabled by default
+func TestDefaultConfig_SPIToolDisabled(t *testing.T) {
+	cfg := DefaultConfig()
+	if cfg.Tools.SPI.Enabled {
+		t.Error("SPI tool should be disabled by default")
+	}
+}
+
 // TestDefaultConfig_WebTools verifies web tools config
 func TestDefaultConfig_WebTools(t *testing.T) {
 	cfg := DefaultConfig()