Feat issue 183 (#189)

* feat: add slash command support (e.g., /show model, /help)

* style: fix code formatting

* feat: implement robust context compression and error recovery with user notifications

cmd/picoclaw/main.go

@@ -594,6 +594,9 @@ func gatewayCmd() {
 		os.Exit(1)
 	}
 
+	// Inject channel manager into agent loop for command handling
+	agentLoop.SetChannelManager(channelManager)
+
 	var transcriber *voice.GroqTranscriber
 	if cfg.Providers.Groq.APIKey != "" {
 		transcriber = voice.NewGroqTranscriber(cfg.Providers.Groq.APIKey)

pkg/agent/loop.go

@@ -19,6 +19,7 @@ import (
 	"unicode/utf8"
 
 	"github.com/sipeed/picoclaw/pkg/bus"
+	"github.com/sipeed/picoclaw/pkg/channels"
 	"github.com/sipeed/picoclaw/pkg/config"
 	"github.com/sipeed/picoclaw/pkg/constants"
 	"github.com/sipeed/picoclaw/pkg/logger"
@@ -42,6 +43,7 @@ type AgentLoop struct {
 	tools          *tools.ToolRegistry
 	running        atomic.Bool
 	summarizing    sync.Map // Tracks which sessions are currently being summarized
+	channelManager *channels.Manager
 }
 
 // processOptions configures how a message is processed
@@ -199,6 +201,10 @@ func (al *AgentLoop) RegisterTool(tool tools.Tool) {
 	al.tools.Register(tool)
 }
 
+func (al *AgentLoop) SetChannelManager(cm *channels.Manager) {
+	al.channelManager = cm
+}
+
 // RecordLastChannel records the last active channel for this workspace.
 // This uses the atomic state save mechanism to prevent data loss on crash.
 func (al *AgentLoop) RecordLastChannel(channel string) error {
@@ -263,6 +269,11 @@ func (al *AgentLoop) processMessage(ctx context.Context, msg bus.InboundMessage)
 		return al.processSystemMessage(ctx, msg)
 	}
 
+	// Check for commands
+	if response, handled := al.handleCommand(ctx, msg); handled {
+		return response, nil
+	}
+
 	// Process as user message
 	return al.runAgentLoop(ctx, processOptions{
 		SessionKey:      msg.SessionKey,
@@ -383,7 +394,7 @@ func (al *AgentLoop) runAgentLoop(ctx context.Context, opts processOptions) (str
 
 	// 7. Optional: summarization
 	if opts.EnableSummary {
-		al.maybeSummarize(opts.SessionKey)
+		al.maybeSummarize(opts.SessionKey, opts.Channel, opts.ChatID)
 	}
 
 	// 8. Optional: send response via bus
@@ -445,11 +456,131 @@ func (al *AgentLoop) runLLMIteration(ctx context.Context, messages []providers.M
 				"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,
-		})
+		var response *providers.LLMResponse
+		var err error
+
+		// Retry loop for context/token errors
+		maxRetries := 2
+		for retry := 0; retry <= maxRetries; retry++ {
+			response, err = al.provider.Chat(ctx, messages, providerToolDefs, al.model, map[string]interface{}{
+				"max_tokens":  8192,
+				"temperature": 0.7,
+			})
+
+			if err == nil {
+				break // Success
+			}
+
+			errMsg := strings.ToLower(err.Error())
+			// Check for context window errors (provider specific, but usually contain "token" or "invalid")
+			isContextError := strings.Contains(errMsg, "token") ||
+				strings.Contains(errMsg, "context") ||
+				strings.Contains(errMsg, "invalidparameter") ||
+				strings.Contains(errMsg, "length")
+
+			if isContextError && retry < maxRetries {
+				logger.WarnCF("agent", "Context window error detected, attempting compression", map[string]interface{}{
+					"error": err.Error(),
+					"retry": retry,
+				})
+
+				// Notify user on first retry only
+				if retry == 0 && !constants.IsInternalChannel(opts.Channel) && opts.SendResponse {
+					al.bus.PublishOutbound(bus.OutboundMessage{
+						Channel: opts.Channel,
+						ChatID:  opts.ChatID,
+						Content: "⚠️ Context window exceeded. Compressing history and retrying...",
+					})
+				}
+
+				// Force compression
+				al.forceCompression(opts.SessionKey)
+
+				// Rebuild messages with compressed history
+				// Note: We need to reload history from session manager because forceCompression changed it
+				newHistory := al.sessions.GetHistory(opts.SessionKey)
+				newSummary := al.sessions.GetSummary(opts.SessionKey)
+
+				// Re-create messages for the next attempt
+				// We keep the current user message (opts.UserMessage) effectively
+				messages = al.contextBuilder.BuildMessages(
+					newHistory,
+					newSummary,
+					opts.UserMessage,
+					nil,
+					opts.Channel,
+					opts.ChatID,
+				)
+
+				// Important: If we are in the middle of a tool loop (iteration > 1),
+				// rebuilding messages from session history might duplicate the flow or miss context
+				// if intermediate steps weren't saved correctly.
+				// However, al.sessions.AddFullMessage is called after every tool execution,
+				// so GetHistory should reflect the current state including partial tool execution.
+				// But we need to ensure we don't duplicate the user message which is appended in BuildMessages.
+				// BuildMessages(history...) takes the stored history and appends the *current* user message.
+				// If iteration > 1, the "current user message" was already added to history in step 3 of runAgentLoop.
+				// So if we pass opts.UserMessage again, we might duplicate it?
+				// Actually, step 3 is: al.sessions.AddMessage(opts.SessionKey, "user", opts.UserMessage)
+				// So GetHistory ALREADY contains the user message!
+
+				// CORRECTION:
+				// BuildMessages combines: [System] + [History] + [CurrentMessage]
+				// But Step 3 added CurrentMessage to History.
+				// So if we use GetHistory now, it has the user message.
+				// If we pass opts.UserMessage to BuildMessages, it adds it AGAIN.
+
+				// For retry in the middle of a loop, we should rely on what's in the session.
+				// BUT checking BuildMessages implementation:
+				// It appends history... then appends currentMessage.
+
+				// Logic fix for retry:
+				// If iteration == 1, opts.UserMessage corresponds to the user input.
+				// If iteration > 1, we are processing tool results. The "messages" passed to Chat
+				// already accumulated tool outputs.
+				// Rebuilding from session history is safest because it persists state.
+				// Start fresh with rebuilt history.
+
+				// Special case: standard BuildMessages appends "currentMessage".
+				// If we are strictly retrying the *LLM call*, we want the exact same state as before but compressed.
+				// However, the "messages" argument passed to runLLMIteration is constructed by the caller.
+				// If we rebuild from Session, we need to know if "currentMessage" should be appended or is already in history.
+
+				// In runAgentLoop:
+				// 3. sessions.AddMessage(userMsg)
+				// 4. runLLMIteration(..., UserMessage)
+
+				// So History contains the user message.
+				// BuildMessages typically appends the user message as a *new* pending message.
+				// Wait, standard BuildMessages usage in runAgentLoop:
+				// messages := BuildMessages(history (has old), UserMessage)
+				// THEN AddMessage(UserMessage).
+				// So "history" passed to BuildMessages does NOT contain the current UserMessage yet.
+
+				// But here, inside the loop, we have already saved it.
+				// So GetHistory() includes the current user message.
+				// If we call BuildMessages(GetHistory(), UserMessage), we get duplicates.
+
+				// Hack/Fix:
+				// If we are retrying, we rebuild from Session History ONLY.
+				// We pass empty string as "currentMessage" to BuildMessages
+				// because the "current message" is already saved in history (step 3).
+
+				messages = al.contextBuilder.BuildMessages(
+					newHistory,
+					newSummary,
+					"", // Empty because history already contains the relevant messages
+					nil,
+					opts.Channel,
+					opts.ChatID,
+				)
+
+				continue
+			}
+
+			// Real error or success, break loop
+			break
+		}
 
 		if err != nil {
 			logger.ErrorCF("agent", "LLM call failed",
@@ -457,7 +588,7 @@ func (al *AgentLoop) runLLMIteration(ctx context.Context, messages []providers.M
 					"iteration": iteration,
 					"error":     err.Error(),
 				})
-			return "", iteration, fmt.Errorf("LLM call failed: %w", err)
+			return "", iteration, fmt.Errorf("LLM call failed after retries: %w", err)
 		}
 
 		// Check if no tool calls - we're done
@@ -589,7 +720,7 @@ func (al *AgentLoop) updateToolContexts(channel, chatID string) {
 }
 
 // maybeSummarize triggers summarization if the session history exceeds thresholds.
-func (al *AgentLoop) maybeSummarize(sessionKey string) {
+func (al *AgentLoop) maybeSummarize(sessionKey, channel, chatID string) {
 	newHistory := al.sessions.GetHistory(sessionKey)
 	tokenEstimate := al.estimateTokens(newHistory)
 	threshold := al.contextWindow * 75 / 100
@@ -598,12 +729,80 @@ func (al *AgentLoop) maybeSummarize(sessionKey string) {
 		if _, loading := al.summarizing.LoadOrStore(sessionKey, true); !loading {
 			go func() {
 				defer al.summarizing.Delete(sessionKey)
+				// Notify user about optimization if not an internal channel
+				if !constants.IsInternalChannel(channel) {
+					al.bus.PublishOutbound(bus.OutboundMessage{
+						Channel: channel,
+						ChatID:  chatID,
+						Content: "⚠️ Memory threshold reached. Optimizing conversation history...",
+					})
+				}
 				al.summarizeSession(sessionKey)
 			}()
 		}
 	}
 }
 
+// forceCompression aggressively reduces context when the limit is hit.
+// It drops the oldest 50% of messages (keeping system prompt and last user message).
+func (al *AgentLoop) forceCompression(sessionKey string) {
+	history := al.sessions.GetHistory(sessionKey)
+	if len(history) <= 4 {
+		return
+	}
+
+	// Keep system prompt (usually [0]) and the very last message (user's trigger)
+	// We want to drop the oldest half of the *conversation*
+	// Assuming [0] is system, [1:] is conversation
+	conversation := history[1 : len(history)-1]
+	if len(conversation) == 0 {
+		return
+	}
+
+	// Helper to find the mid-point of the conversation
+	mid := len(conversation) / 2
+
+	// New history structure:
+	// 1. System Prompt
+	// 2. [Summary of dropped part] - synthesized
+	// 3. Second half of conversation
+	// 4. Last message
+
+	// Simplified approach for emergency: Drop first half of conversation
+	// and rely on existing summary if present, or create a placeholder.
+
+	droppedCount := mid
+	keptConversation := conversation[mid:]
+
+	newHistory := make([]providers.Message, 0)
+	newHistory = append(newHistory, history[0]) // System prompt
+
+	// Add a note about compression
+	compressionNote := fmt.Sprintf("[System: Emergency compression dropped %d oldest messages due to context limit]", droppedCount)
+	// If there was an existing summary, we might lose it if it was in the dropped part (which is just messages).
+	// The summary is stored separately in session.Summary, so it persists!
+	// We just need to ensure the user knows there's a gap.
+
+	// We only modify the messages list here
+	newHistory = append(newHistory, providers.Message{
+		Role:    "system",
+		Content: compressionNote,
+	})
+
+	newHistory = append(newHistory, keptConversation...)
+	newHistory = append(newHistory, history[len(history)-1]) // Last message
+
+	// Update session
+	al.sessions.SetHistory(sessionKey, newHistory)
+	al.sessions.Save(sessionKey)
+
+	logger.WarnCF("agent", "Forced compression executed", map[string]interface{}{
+		"session_key":  sessionKey,
+		"dropped_msgs": droppedCount,
+		"new_count":    len(newHistory),
+	})
+}
+
 // GetStartupInfo returns information about loaded tools and skills for logging.
 func (al *AgentLoop) GetStartupInfo() map[string]interface{} {
 	info := make(map[string]interface{})
@@ -631,7 +830,7 @@ func formatMessagesForLog(messages []providers.Message) string {
 	result += "[\n"
 	for i, msg := range messages {
 		result += fmt.Sprintf("  [%d] Role: %s\n", i, msg.Role)
-		if msg.ToolCalls != nil && len(msg.ToolCalls) > 0 {
+		if len(msg.ToolCalls) > 0 {
 			result += "  ToolCalls:\n"
 			for _, tc := range msg.ToolCalls {
 				result += fmt.Sprintf("    - ID: %s, Type: %s, Name: %s\n", tc.ID, tc.Type, tc.Name)
@@ -698,7 +897,7 @@ func (al *AgentLoop) summarizeSession(sessionKey string) {
 			continue
 		}
 		// Estimate tokens for this message
-		msgTokens := len(m.Content) / 4
+		msgTokens := len(m.Content) / 2 // Use safer estimate here too (2.5 -> 2 for integer division safety)
 		if msgTokens > maxMessageTokens {
 			omitted = true
 			continue
@@ -769,13 +968,96 @@ func (al *AgentLoop) summarizeBatch(ctx context.Context, batch []providers.Messa
 }
 
 // estimateTokens estimates the number of tokens in a message list.
-// Uses rune count instead of byte length so that CJK and other multi-byte
-// characters are not over-counted (a Chinese character is 3 bytes but roughly
-// one token).
+// Uses a safe heuristic of 2.5 characters per token to account for CJK and other
+// overheads better than the previous 3 chars/token.
 func (al *AgentLoop) estimateTokens(messages []providers.Message) int {
-	total := 0
+	totalChars := 0
 	for _, m := range messages {
-		total += utf8.RuneCountInString(m.Content) / 3
+		totalChars += utf8.RuneCountInString(m.Content)
 	}
-	return total
+	// 2.5 chars per token = totalChars * 2 / 5
+	return totalChars * 2 / 5
+}
+
+func (al *AgentLoop) handleCommand(ctx context.Context, msg bus.InboundMessage) (string, bool) {
+	content := strings.TrimSpace(msg.Content)
+	if !strings.HasPrefix(content, "/") {
+		return "", false
+	}
+
+	parts := strings.Fields(content)
+	if len(parts) == 0 {
+		return "", false
+	}
+
+	cmd := parts[0]
+	args := parts[1:]
+
+	switch cmd {
+	case "/show":
+		if len(args) < 1 {
+			return "Usage: /show [model|channel]", true
+		}
+		switch args[0] {
+		case "model":
+			return fmt.Sprintf("Current model: %s", al.model), true
+		case "channel":
+			return fmt.Sprintf("Current channel: %s", msg.Channel), true
+		default:
+			return fmt.Sprintf("Unknown show target: %s", args[0]), true
+		}
+
+	case "/list":
+		if len(args) < 1 {
+			return "Usage: /list [models|channels]", true
+		}
+		switch args[0] {
+		case "models":
+			// TODO: Fetch available models dynamically if possible
+			return "Available models: glm-4.7, claude-3-5-sonnet, gpt-4o (configured in config.json/env)", true
+		case "channels":
+			if al.channelManager == nil {
+				return "Channel manager not initialized", true
+			}
+			channels := al.channelManager.GetEnabledChannels()
+			if len(channels) == 0 {
+				return "No channels enabled", true
+			}
+			return fmt.Sprintf("Enabled channels: %s", strings.Join(channels, ", ")), true
+		default:
+			return fmt.Sprintf("Unknown list target: %s", args[0]), true
+		}
+
+	case "/switch":
+		if len(args) < 3 || args[1] != "to" {
+			return "Usage: /switch [model|channel] to <name>", true
+		}
+		target := args[0]
+		value := args[2]
+
+		switch target {
+		case "model":
+			oldModel := al.model
+			al.model = value
+			return fmt.Sprintf("Switched model from %s to %s", oldModel, value), true
+		case "channel":
+			// This changes the 'default' channel for some operations, or effectively redirects output?
+			// For now, let's just validate if the channel exists
+			if al.channelManager == nil {
+				return "Channel manager not initialized", true
+			}
+			if _, exists := al.channelManager.GetChannel(value); !exists && value != "cli" {
+				return fmt.Sprintf("Channel '%s' not found or not enabled", value), true
+			}
+
+			// If message came from CLI, maybe we want to redirect CLI output to this channel?
+			// That would require state persistence about "redirected channel"
+			// For now, just acknowledged.
+			return fmt.Sprintf("Switched target channel to %s (Note: this currently only validates existence)", value), true
+		default:
+			return fmt.Sprintf("Unknown switch target: %s", target), true
+		}
+	}
+
+	return "", false
 }

pkg/agent/loop_test.go

@@ -2,6 +2,7 @@ package agent
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
@@ -527,3 +528,99 @@ func TestToolResult_UserFacingToolDoesSendMessage(t *testing.T) {
 		t.Errorf("Expected 'Command output: hello world', got: %s", response)
 	}
 }
+
+// failFirstMockProvider fails on the first N calls with a specific error
+type failFirstMockProvider struct {
+	failures    int
+	currentCall int
+	failError   error
+	successResp string
+}
+
+func (m *failFirstMockProvider) Chat(ctx context.Context, messages []providers.Message, tools []providers.ToolDefinition, model string, opts map[string]interface{}) (*providers.LLMResponse, error) {
+	m.currentCall++
+	if m.currentCall <= m.failures {
+		return nil, m.failError
+	}
+	return &providers.LLMResponse{
+		Content:   m.successResp,
+		ToolCalls: []providers.ToolCall{},
+	}, nil
+}
+
+func (m *failFirstMockProvider) GetDefaultModel() string {
+	return "mock-fail-model"
+}
+
+// TestAgentLoop_ContextExhaustionRetry verify that the agent retries on context errors
+func TestAgentLoop_ContextExhaustionRetry(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,
+			},
+		},
+	}
+
+	msgBus := bus.NewMessageBus()
+
+	// Create a provider that fails once with a context error
+	contextErr := fmt.Errorf("InvalidParameter: Total tokens of image and text exceed max message tokens")
+	provider := &failFirstMockProvider{
+		failures:    1,
+		failError:   contextErr,
+		successResp: "Recovered from context error",
+	}
+
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	// Inject some history to simulate a full context
+	sessionKey := "test-session-context"
+	// Create dummy history
+	history := []providers.Message{
+		{Role: "system", Content: "System prompt"},
+		{Role: "user", Content: "Old message 1"},
+		{Role: "assistant", Content: "Old response 1"},
+		{Role: "user", Content: "Old message 2"},
+		{Role: "assistant", Content: "Old response 2"},
+		{Role: "user", Content: "Trigger message"},
+	}
+	al.sessions.SetHistory(sessionKey, history)
+
+	// Call ProcessDirectWithChannel
+	// Note: ProcessDirectWithChannel calls processMessage which will execute runLLMIteration
+	response, err := al.ProcessDirectWithChannel(context.Background(), "Trigger message", sessionKey, "test", "test-chat")
+
+	if err != nil {
+		t.Fatalf("Expected success after retry, got error: %v", err)
+	}
+
+	if response != "Recovered from context error" {
+		t.Errorf("Expected 'Recovered from context error', got '%s'", response)
+	}
+
+	// We expect 2 calls: 1st failed, 2nd succeeded
+	if provider.currentCall != 2 {
+		t.Errorf("Expected 2 calls (1 fail + 1 success), got %d", provider.currentCall)
+	}
+
+	// Check final history length
+	finalHistory := al.sessions.GetHistory(sessionKey)
+	// We verify that the history has been modified (compressed)
+	// Original length: 6
+	// Expected behavior: compression drops ~50% of history (mid slice)
+	// We can assert that the length is NOT what it would be without compression.
+	// Without compression: 6 + 1 (new user msg) + 1 (assistant msg) = 8
+	if len(finalHistory) >= 8 {
+		t.Errorf("Expected history to be compressed (len < 8), got %d", len(finalHistory))
+	}
+}

pkg/session/manager.go

@@ -264,3 +264,19 @@ func (sm *SessionManager) loadSessions() error {
 
 	return nil
 }
+
+// SetHistory updates the messages of a session.
+func (sm *SessionManager) SetHistory(key string, history []providers.Message) {
+	sm.mu.Lock()
+	defer sm.mu.Unlock()
+
+	session, ok := sm.sessions[key]
+	if ok {
+		// Create a deep copy to strictly isolate internal state
+		// from the caller's slice.
+		msgs := make([]providers.Message, len(history))
+		copy(msgs, history)
+		session.Messages = msgs
+		session.Updated = time.Now()
+	}
+}