refactor(tools): remove duplicate truncate functions and add docs

- Remove duplicate truncate/truncateString functions from loop.go and cron.go
- Use utils.Truncate consistently across codebase
- Add Workspace Layout section to README
- Document cron/scheduled tasks functionality

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

pkg/agent/loop.go

@@ -22,6 +22,7 @@ import (
 	"github.com/sipeed/picoclaw/pkg/providers"
 	"github.com/sipeed/picoclaw/pkg/session"
 	"github.com/sipeed/picoclaw/pkg/tools"
+	"github.com/sipeed/picoclaw/pkg/utils"
 )
 
 type AgentLoop struct {
@@ -38,6 +39,17 @@ type AgentLoop struct {
 	summarizing    sync.Map      // Tracks which sessions are currently being summarized
 }
 
+// processOptions configures how a message is processed
+type processOptions struct {
+	SessionKey      string // Session identifier for history/context
+	Channel         string // Target channel for tool execution
+	ChatID          string // Target chat ID for tool execution
+	UserMessage     string // User message content (may include prefix)
+	DefaultResponse string // Response when LLM returns empty
+	EnableSummary   bool   // Whether to trigger summarization
+	SendResponse    bool   // Whether to send response via bus
+}
+
 func NewAgentLoop(cfg *config.Config, msgBus *bus.MessageBus, provider providers.LLMProvider) *AgentLoop {
 	workspace := cfg.WorkspacePath()
 	os.MkdirAll(workspace, 0755)
@@ -151,7 +163,7 @@ func (al *AgentLoop) ProcessDirectWithChannel(ctx context.Context, content, sess
 
 func (al *AgentLoop) processMessage(ctx context.Context, msg bus.InboundMessage) (string, error) {
 	// Add message preview to log
-	preview := truncate(msg.Content, 80)
+	preview := utils.Truncate(msg.Content, 80)
 	logger.InfoCF("agent", fmt.Sprintf("Processing message from %s:%s: %s", msg.Channel, msg.SenderID, preview),
 		map[string]interface{}{
 			"channel":     msg.Channel,
@@ -165,193 +177,16 @@ func (al *AgentLoop) processMessage(ctx context.Context, msg bus.InboundMessage)
 		return al.processSystemMessage(ctx, msg)
 	}
 
-	// Update tool contexts
-	if tool, ok := al.tools.Get("message"); ok {
-		if mt, ok := tool.(*tools.MessageTool); ok {
-			mt.SetContext(msg.Channel, msg.ChatID)
-		}
-	}
-	if tool, ok := al.tools.Get("spawn"); ok {
-		if st, ok := tool.(*tools.SpawnTool); ok {
-			st.SetContext(msg.Channel, msg.ChatID)
-		}
-	}
-
-	history := al.sessions.GetHistory(msg.SessionKey)
-	summary := al.sessions.GetSummary(msg.SessionKey)
-
-	messages := al.contextBuilder.BuildMessages(
-		history,
-		summary,
-		msg.Content,
-		nil,
-		msg.Channel,
-		msg.ChatID,
-	)
-
-	// Save user message to session
-	al.sessions.AddMessage(msg.SessionKey, "user", msg.Content)
-
-	iteration := 0
-	var finalContent string
-
-	for iteration < al.maxIterations {
-		iteration++
-
-		logger.DebugCF("agent", "LLM iteration",
-			map[string]interface{}{
-				"iteration": iteration,
-				"max":       al.maxIterations,
-			})
-
-		toolDefs := al.tools.GetDefinitions()
-		providerToolDefs := make([]providers.ToolDefinition, 0, len(toolDefs))
-		for _, td := range toolDefs {
-			providerToolDefs = append(providerToolDefs, providers.ToolDefinition{
-				Type: td["type"].(string),
-				Function: providers.ToolFunctionDefinition{
-					Name:        td["function"].(map[string]interface{})["name"].(string),
-					Description: td["function"].(map[string]interface{})["description"].(string),
-					Parameters:  td["function"].(map[string]interface{})["parameters"].(map[string]interface{}),
-				},
-			})
-		}
-
-		// Log LLM request details
-		logger.DebugCF("agent", "LLM request",
-			map[string]interface{}{
-				"iteration":        iteration,
-				"model":            al.model,
-				"messages_count":   len(messages),
-				"tools_count":      len(providerToolDefs),
-				"max_tokens":       8192,
-				"temperature":      0.7,
-				"system_prompt_len": len(messages[0].Content),
-			})
-
-		// Log full messages (detailed)
-		logger.DebugCF("agent", "Full LLM request",
-			map[string]interface{}{
-				"iteration":     iteration,
-				"messages_json": formatMessagesForLog(messages),
-				"tools_json":    formatToolsForLog(providerToolDefs),
-			})
-
-		response, err := al.provider.Chat(ctx, messages, providerToolDefs, al.model, map[string]interface{}{
-			"max_tokens":  8192,
-			"temperature": 0.7,
-		})
-
-		if err != nil {
-			logger.ErrorCF("agent", "LLM call failed",
-				map[string]interface{}{
-					"iteration": iteration,
-					"error":     err.Error(),
-				})
-			return "", fmt.Errorf("LLM call failed: %w", err)
-		}
-
-		if len(response.ToolCalls) == 0 {
-			finalContent = response.Content
-			logger.InfoCF("agent", "LLM response without tool calls (direct answer)",
-				map[string]interface{}{
-					"iteration":     iteration,
-					"content_chars": len(finalContent),
-				})
-			break
-		}
-
-		toolNames := make([]string, 0, len(response.ToolCalls))
-		for _, tc := range response.ToolCalls {
-			toolNames = append(toolNames, tc.Name)
-		}
-		logger.InfoCF("agent", "LLM requested tool calls",
-			map[string]interface{}{
-				"tools":     toolNames,
-				"count":     len(toolNames),
-				"iteration": iteration,
-			})
-
-		assistantMsg := providers.Message{
-			Role:    "assistant",
-			Content: response.Content,
-		}
-
-		for _, tc := range response.ToolCalls {
-			argumentsJSON, _ := json.Marshal(tc.Arguments)
-			assistantMsg.ToolCalls = append(assistantMsg.ToolCalls, providers.ToolCall{
-				ID:   tc.ID,
-				Type: "function",
-				Function: &providers.FunctionCall{
-					Name:      tc.Name,
-					Arguments: string(argumentsJSON),
-				},
-			})
-		}
-		messages = append(messages, assistantMsg)
-
-		// Save assistant message with tool calls to session
-		al.sessions.AddFullMessage(msg.SessionKey, assistantMsg)
-
-		for _, tc := range response.ToolCalls {
-			// Log tool call with arguments preview
-			argsJSON, _ := json.Marshal(tc.Arguments)
-			argsPreview := truncate(string(argsJSON), 200)
-			logger.InfoCF("agent", fmt.Sprintf("Tool call: %s(%s)", tc.Name, argsPreview),
-				map[string]interface{}{
-					"tool":       tc.Name,
-					"iteration":  iteration,
-				})
-
-			result, err := al.tools.ExecuteWithContext(ctx, tc.Name, tc.Arguments, msg.Channel, msg.ChatID)
-			if err != nil {
-				result = fmt.Sprintf("Error: %v", err)
-			}
-
-			toolResultMsg := providers.Message{
-				Role:       "tool",
-				Content:    result,
-				ToolCallID: tc.ID,
-			}
-			messages = append(messages, toolResultMsg)
-
-			// Save tool result message to session
-			al.sessions.AddFullMessage(msg.SessionKey, toolResultMsg)
-		}
-	}
-
-	if finalContent == "" {
-		finalContent = "I've completed processing but have no response to give."
-	}
-
-	// Save final assistant message to session
-	al.sessions.AddMessage(msg.SessionKey, "assistant", finalContent)
-	al.sessions.Save(al.sessions.GetOrCreate(msg.SessionKey))
-
-	// Context compression: Check if we need to summarize
-	// Trigger if history > 20 messages OR estimated tokens > 75% of context window
-	newHistory := al.sessions.GetHistory(msg.SessionKey)
-	tokenEstimate := al.estimateTokens(newHistory)
-	threshold := al.contextWindow * 75 / 100
-
-	if len(newHistory) > 20 || tokenEstimate > threshold {
-		if _, loading := al.summarizing.LoadOrStore(msg.SessionKey, true); !loading {
-			go func() {
-				defer al.summarizing.Delete(msg.SessionKey)
-				al.summarizeSession(msg.SessionKey)
-			}()
-		}
-	}
-
-	// Log response preview
-	responsePreview := truncate(finalContent, 120)
-	logger.InfoCF("agent", fmt.Sprintf("Response to %s:%s: %s", msg.Channel, msg.SenderID, responsePreview),
-		map[string]interface{}{
-			"iterations":   iteration,
-			"final_length": len(finalContent),
-		})
-
-	return finalContent, nil
+	// Process as user message
+	return al.runAgentLoop(ctx, processOptions{
+		SessionKey:      msg.SessionKey,
+		Channel:         msg.Channel,
+		ChatID:          msg.ChatID,
+		UserMessage:     msg.Content,
+		DefaultResponse: "I've completed processing but have no response to give.",
+		EnableSummary:   true,
+		SendResponse:    false,
+	})
 }
 
 func (al *AgentLoop) processSystemMessage(ctx context.Context, msg bus.InboundMessage) (string, error) {
@@ -380,39 +215,96 @@ func (al *AgentLoop) processSystemMessage(ctx context.Context, msg bus.InboundMe
 	// Use the origin session for context
 	sessionKey := fmt.Sprintf("%s:%s", originChannel, originChatID)
 
-	// Update tool contexts to original channel/chatID
-	if tool, ok := al.tools.Get("message"); ok {
-		if mt, ok := tool.(*tools.MessageTool); ok {
-			mt.SetContext(originChannel, originChatID)
-		}
-	}
-	if tool, ok := al.tools.Get("spawn"); ok {
-		if st, ok := tool.(*tools.SpawnTool); ok {
-			st.SetContext(originChannel, originChatID)
-		}
-	}
+	// Process as system message with routing back to origin
+	return al.runAgentLoop(ctx, processOptions{
+		SessionKey:      sessionKey,
+		Channel:         originChannel,
+		ChatID:          originChatID,
+		UserMessage:     fmt.Sprintf("[System: %s] %s", msg.SenderID, msg.Content),
+		DefaultResponse: "Background task completed.",
+		EnableSummary:   false,
+		SendResponse:    true, // Send response back to original channel
+	})
+}
 
-	// Build messages with the announce content
-	history := al.sessions.GetHistory(sessionKey)
-	summary := al.sessions.GetSummary(sessionKey)
+// runAgentLoop is the core message processing logic.
+// It handles context building, LLM calls, tool execution, and response handling.
+func (al *AgentLoop) runAgentLoop(ctx context.Context, opts processOptions) (string, error) {
+	// 1. Update tool contexts
+	al.updateToolContexts(opts.Channel, opts.ChatID)
+
+	// 2. Build messages
+	history := al.sessions.GetHistory(opts.SessionKey)
+	summary := al.sessions.GetSummary(opts.SessionKey)
 	messages := al.contextBuilder.BuildMessages(
 		history,
 		summary,
-		msg.Content,
+		opts.UserMessage,
 		nil,
-		originChannel,
-		originChatID,
+		opts.Channel,
+		opts.ChatID,
 	)
 
-	// Save user message to session with system message marker
-	al.sessions.AddMessage(sessionKey, "user", fmt.Sprintf("[System: %s] %s", msg.SenderID, msg.Content))
+	// 3. Save user message to session
+	al.sessions.AddMessage(opts.SessionKey, "user", opts.UserMessage)
 
+	// 4. Run LLM iteration loop
+	finalContent, iteration, err := al.runLLMIteration(ctx, messages, opts)
+	if err != nil {
+		return "", err
+	}
+
+	// 5. Handle empty response
+	if finalContent == "" {
+		finalContent = opts.DefaultResponse
+	}
+
+	// 6. Save final assistant message to session
+	al.sessions.AddMessage(opts.SessionKey, "assistant", finalContent)
+	al.sessions.Save(al.sessions.GetOrCreate(opts.SessionKey))
+
+	// 7. Optional: summarization
+	if opts.EnableSummary {
+		al.maybeSummarize(opts.SessionKey)
+	}
+
+	// 8. Optional: send response via bus
+	if opts.SendResponse {
+		al.bus.PublishOutbound(bus.OutboundMessage{
+			Channel: opts.Channel,
+			ChatID:  opts.ChatID,
+			Content: finalContent,
+		})
+	}
+
+	// 9. Log response
+	responsePreview := utils.Truncate(finalContent, 120)
+	logger.InfoCF("agent", fmt.Sprintf("Response: %s", responsePreview),
+		map[string]interface{}{
+			"session_key":  opts.SessionKey,
+			"iterations":   iteration,
+			"final_length": len(finalContent),
+		})
+
+	return finalContent, nil
+}
+
+// runLLMIteration executes the LLM call loop with tool handling.
+// Returns the final content, iteration count, and any error.
+func (al *AgentLoop) runLLMIteration(ctx context.Context, messages []providers.Message, opts processOptions) (string, int, error) {
 	iteration := 0
 	var finalContent string
 
 	for iteration < al.maxIterations {
 		iteration++
 
+		logger.DebugCF("agent", "LLM iteration",
+			map[string]interface{}{
+				"iteration": iteration,
+				"max":       al.maxIterations,
+			})
+
+		// Build tool definitions
 		toolDefs := al.tools.GetDefinitions()
 		providerToolDefs := make([]providers.ToolDefinition, 0, len(toolDefs))
 		for _, td := range toolDefs {
@@ -429,12 +321,12 @@ func (al *AgentLoop) processSystemMessage(ctx context.Context, msg bus.InboundMe
 		// Log LLM request details
 		logger.DebugCF("agent", "LLM request",
 			map[string]interface{}{
-				"iteration":        iteration,
-				"model":            al.model,
-				"messages_count":   len(messages),
-				"tools_count":      len(providerToolDefs),
-				"max_tokens":       8192,
-				"temperature":      0.7,
+				"iteration":         iteration,
+				"model":             al.model,
+				"messages_count":    len(messages),
+				"tools_count":       len(providerToolDefs),
+				"max_tokens":        8192,
+				"temperature":       0.7,
 				"system_prompt_len": len(messages[0].Content),
 			})
 
@@ -446,30 +338,49 @@ func (al *AgentLoop) processSystemMessage(ctx context.Context, msg bus.InboundMe
 				"tools_json":    formatToolsForLog(providerToolDefs),
 			})
 
+		// Call LLM
 		response, err := al.provider.Chat(ctx, messages, providerToolDefs, al.model, map[string]interface{}{
 			"max_tokens":  8192,
 			"temperature": 0.7,
 		})
 
 		if err != nil {
-			logger.ErrorCF("agent", "LLM call failed in system message",
+			logger.ErrorCF("agent", "LLM call failed",
 				map[string]interface{}{
 					"iteration": iteration,
 					"error":     err.Error(),
 				})
-			return "", fmt.Errorf("LLM call failed: %w", err)
+			return "", iteration, fmt.Errorf("LLM call failed: %w", err)
 		}
 
+		// Check if no tool calls - we're done
 		if len(response.ToolCalls) == 0 {
 			finalContent = response.Content
+			logger.InfoCF("agent", "LLM response without tool calls (direct answer)",
+				map[string]interface{}{
+					"iteration":     iteration,
+					"content_chars": len(finalContent),
+				})
 			break
 		}
 
+		// Log tool calls
+		toolNames := make([]string, 0, len(response.ToolCalls))
+		for _, tc := range response.ToolCalls {
+			toolNames = append(toolNames, tc.Name)
+		}
+		logger.InfoCF("agent", "LLM requested tool calls",
+			map[string]interface{}{
+				"tools":     toolNames,
+				"count":     len(toolNames),
+				"iteration": iteration,
+			})
+
+		// Build assistant message with tool calls
 		assistantMsg := providers.Message{
 			Role:    "assistant",
 			Content: response.Content,
 		}
-
 		for _, tc := range response.ToolCalls {
 			argumentsJSON, _ := json.Marshal(tc.Arguments)
 			assistantMsg.ToolCalls = append(assistantMsg.ToolCalls, providers.ToolCall{
@@ -484,10 +395,20 @@ func (al *AgentLoop) processSystemMessage(ctx context.Context, msg bus.InboundMe
 		messages = append(messages, assistantMsg)
 
 		// Save assistant message with tool calls to session
-		al.sessions.AddFullMessage(sessionKey, assistantMsg)
+		al.sessions.AddFullMessage(opts.SessionKey, assistantMsg)
 
+		// Execute tool calls
 		for _, tc := range response.ToolCalls {
-			result, err := al.tools.ExecuteWithContext(ctx, tc.Name, tc.Arguments, msg.Channel, msg.ChatID)
+			// Log tool call with arguments preview
+			argsJSON, _ := json.Marshal(tc.Arguments)
+			argsPreview := utils.Truncate(string(argsJSON), 200)
+			logger.InfoCF("agent", fmt.Sprintf("Tool call: %s(%s)", tc.Name, argsPreview),
+				map[string]interface{}{
+					"tool":      tc.Name,
+					"iteration": iteration,
+				})
+
+			result, err := al.tools.ExecuteWithContext(ctx, tc.Name, tc.Arguments, opts.Channel, opts.ChatID)
 			if err != nil {
 				result = fmt.Sprintf("Error: %v", err)
 			}
@@ -500,46 +421,41 @@ func (al *AgentLoop) processSystemMessage(ctx context.Context, msg bus.InboundMe
 			messages = append(messages, toolResultMsg)
 
 			// Save tool result message to session
-			al.sessions.AddFullMessage(sessionKey, toolResultMsg)
+			al.sessions.AddFullMessage(opts.SessionKey, toolResultMsg)
 		}
 	}
 
-	if finalContent == "" {
-		finalContent = "Background task completed."
-	}
-
-	// Save final assistant message to session
-	al.sessions.AddMessage(sessionKey, "assistant", finalContent)
-	al.sessions.Save(al.sessions.GetOrCreate(sessionKey))
-
-	logger.InfoCF("agent", "System message processing completed",
-		map[string]interface{}{
-			"iterations":   iteration,
-			"final_length": len(finalContent),
-		})
-
-	// Send response back to the original channel
-	al.bus.PublishOutbound(bus.OutboundMessage{
-		Channel: originChannel,
-		ChatID:  originChatID,
-		Content: finalContent,
-	})
-
-	return finalContent, nil
+	return finalContent, iteration, nil
 }
 
-// truncate returns a truncated version of s with at most maxLen characters.
-// If the string is truncated, "..." is appended to indicate truncation.
-// If the string fits within maxLen, it is returned unchanged.
-func truncate(s string, maxLen int) string {
-	if len(s) <= maxLen {
-		return s
+// updateToolContexts updates the context for tools that need channel/chatID info.
+func (al *AgentLoop) updateToolContexts(channel, chatID string) {
+	if tool, ok := al.tools.Get("message"); ok {
+		if mt, ok := tool.(*tools.MessageTool); ok {
+			mt.SetContext(channel, chatID)
+		}
 	}
-	// Reserve 3 chars for "..."
-	if maxLen <= 3 {
-		return s[:maxLen]
+	if tool, ok := al.tools.Get("spawn"); ok {
+		if st, ok := tool.(*tools.SpawnTool); ok {
+			st.SetContext(channel, chatID)
+		}
+	}
+}
+
+// maybeSummarize triggers summarization if the session history exceeds thresholds.
+func (al *AgentLoop) maybeSummarize(sessionKey string) {
+	newHistory := al.sessions.GetHistory(sessionKey)
+	tokenEstimate := al.estimateTokens(newHistory)
+	threshold := al.contextWindow * 75 / 100
+
+	if len(newHistory) > 20 || tokenEstimate > threshold {
+		if _, loading := al.summarizing.LoadOrStore(sessionKey, true); !loading {
+			go func() {
+				defer al.summarizing.Delete(sessionKey)
+				al.summarizeSession(sessionKey)
+			}()
+		}
 	}
-	return s[:maxLen-3] + "..."
 }
 
 // GetStartupInfo returns information about loaded tools and skills for logging.
@@ -574,12 +490,12 @@ func formatMessagesForLog(messages []providers.Message) string {
 			for _, tc := range msg.ToolCalls {
 				result += fmt.Sprintf("    - ID: %s, Type: %s, Name: %s\n", tc.ID, tc.Type, tc.Name)
 				if tc.Function != nil {
-					result += fmt.Sprintf("      Arguments: %s\n", truncateString(tc.Function.Arguments, 200))
+					result += fmt.Sprintf("      Arguments: %s\n", utils.Truncate(tc.Function.Arguments, 200))
 				}
 			}
 		}
 		if msg.Content != "" {
-			content := truncateString(msg.Content, 200)
+			content := utils.Truncate(msg.Content, 200)
 			result += fmt.Sprintf("  Content: %s\n", content)
 		}
 		if msg.ToolCallID != "" {
@@ -603,24 +519,13 @@ func formatToolsForLog(tools []providers.ToolDefinition) string {
 		result += fmt.Sprintf("  [%d] Type: %s, Name: %s\n", i, tool.Type, tool.Function.Name)
 		result += fmt.Sprintf("      Description: %s\n", tool.Function.Description)
 		if len(tool.Function.Parameters) > 0 {
-			result += fmt.Sprintf("      Parameters: %s\n", truncateString(fmt.Sprintf("%v", tool.Function.Parameters), 200))
+			result += fmt.Sprintf("      Parameters: %s\n", utils.Truncate(fmt.Sprintf("%v", tool.Function.Parameters), 200))
 		}
 	}
 	result += "]"
 	return result
 }
 
-// truncateString truncates a string to max length
-func truncateString(s string, maxLen int) string {
-	if len(s) <= maxLen {
-		return s
-	}
-	if maxLen <= 3 {
-		return s[:maxLen]
-	}
-	return s[:maxLen-3] + "..."
-}
-
 // summarizeSession summarizes the conversation history for a session.
 func (al *AgentLoop) summarizeSession(sessionKey string) {
 	ctx, cancel := context.WithTimeout(context.Background(), 120*time.Second)

pkg/tools/cron.go

@@ -8,15 +8,9 @@ import (
 
 	"github.com/sipeed/picoclaw/pkg/bus"
 	"github.com/sipeed/picoclaw/pkg/cron"
+	"github.com/sipeed/picoclaw/pkg/utils"
 )
 
-func truncateString(s string, maxLen int) string {
-	if len(s) <= maxLen {
-		return s
-	}
-	return s[:maxLen]
-}
-
 // JobExecutor is the interface for executing cron jobs through the agent
 type JobExecutor interface {
 	ProcessDirectWithChannel(ctx context.Context, content, sessionKey, channel, chatID string) (string, error)
@@ -171,8 +165,11 @@ func (t *CronTool) addJob(args map[string]interface{}) (string, error) {
 		deliver = d
 	}
 
+	// Truncate message for job name (max 30 chars)
+	messagePreview := utils.Truncate(message, 30)
+
 	job, err := t.cronService.AddJob(
-		truncateString(message, 30),
+		messagePreview,
 		schedule,
 		message,
 		deliver,