feat: US-010 - Add RecordLastChannel to AgentLoop with atomic state save

- Add state *state.Manager field to AgentLoop struct
- Initialize stateManager in NewAgentLoop using state.NewManager
- Implement RecordLastChannel method that calls state.SetLastChannel
- Implement RecordLastChatID method for chat ID tracking
- Add comprehensive tests for state persistence
- Verify state survives across AgentLoop instances

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

pkg/agent/loop_test.go

@@ -0,0 +1,153 @@
+package agent
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/sipeed/picoclaw/pkg/bus"
+	"github.com/sipeed/picoclaw/pkg/config"
+	"github.com/sipeed/picoclaw/pkg/providers"
+)
+
+// mockProvider is a simple mock LLM provider for testing
+type mockProvider struct{}
+
+func (m *mockProvider) Chat(ctx context.Context, messages []providers.Message, tools []providers.ToolDefinition, model string, opts map[string]interface{}) (*providers.LLMResponse, error) {
+	return &providers.LLMResponse{
+		Content:  "Mock response",
+		ToolCalls: []providers.ToolCall{},
+	}, nil
+}
+
+func (m *mockProvider) GetDefaultModel() string {
+	return "mock-model"
+}
+
+func TestRecordLastChannel(t *testing.T) {
+	// Create temp workspace
+	tmpDir, err := os.MkdirTemp("", "agent-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	// Create test config
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				Model:             "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+	}
+
+	// Create agent loop
+	msgBus := bus.NewMessageBus()
+	provider := &mockProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	// Test RecordLastChannel
+	testChannel := "test-channel"
+	err = al.RecordLastChannel(testChannel)
+	if err != nil {
+		t.Fatalf("RecordLastChannel failed: %v", err)
+	}
+
+	// Verify the channel was saved
+	lastChannel := al.state.GetLastChannel()
+	if lastChannel != testChannel {
+		t.Errorf("Expected channel '%s', got '%s'", testChannel, lastChannel)
+	}
+
+	// Verify persistence by creating a new agent loop
+	al2 := NewAgentLoop(cfg, msgBus, provider)
+	if al2.state.GetLastChannel() != testChannel {
+		t.Errorf("Expected persistent channel '%s', got '%s'", testChannel, al2.state.GetLastChannel())
+	}
+}
+
+func TestRecordLastChatID(t *testing.T) {
+	// Create temp workspace
+	tmpDir, err := os.MkdirTemp("", "agent-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	// Create test config
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				Model:             "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+	}
+
+	// Create agent loop
+	msgBus := bus.NewMessageBus()
+	provider := &mockProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	// Test RecordLastChatID
+	testChatID := "test-chat-id-123"
+	err = al.RecordLastChatID(testChatID)
+	if err != nil {
+		t.Fatalf("RecordLastChatID failed: %v", err)
+	}
+
+	// Verify the chat ID was saved
+	lastChatID := al.state.GetLastChatID()
+	if lastChatID != testChatID {
+		t.Errorf("Expected chat ID '%s', got '%s'", testChatID, lastChatID)
+	}
+
+	// Verify persistence by creating a new agent loop
+	al2 := NewAgentLoop(cfg, msgBus, provider)
+	if al2.state.GetLastChatID() != testChatID {
+		t.Errorf("Expected persistent chat ID '%s', got '%s'", testChatID, al2.state.GetLastChatID())
+	}
+}
+
+func TestNewAgentLoop_StateInitialized(t *testing.T) {
+	// Create temp workspace
+	tmpDir, err := os.MkdirTemp("", "agent-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	// Create test config
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				Model:             "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+	}
+
+	// Create agent loop
+	msgBus := bus.NewMessageBus()
+	provider := &mockProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	// Verify state manager is initialized
+	if al.state == nil {
+		t.Error("Expected state manager to be initialized")
+	}
+
+	// Verify state directory was created
+	stateDir := filepath.Join(tmpDir, "state")
+	if _, err := os.Stat(stateDir); os.IsNotExist(err) {
+		t.Error("Expected state directory to exist")
+	}
+}