fix(message): suppress duplicate sends within same round

pkg/tools/message.go

@@ -12,6 +12,9 @@ type MessageTool struct {
 	defaultChannel string
 	defaultChatID  string
 	sentInRound    bool // Tracks whether a message was sent in the current processing round
+	lastChannel    string
+	lastChatID     string
+	lastContent    string
 }
 
 func NewMessageTool() *MessageTool {
@@ -51,6 +54,9 @@ func (t *MessageTool) SetContext(channel, chatID string) {
 	t.defaultChannel = channel
 	t.defaultChatID = chatID
 	t.sentInRound = false // Reset send tracking for new processing round
+	t.lastChannel = ""
+	t.lastChatID = ""
+	t.lastContent = ""
 }
 
 // HasSentInRound returns true if the message tool sent a message during the current round.
@@ -86,6 +92,15 @@ func (t *MessageTool) Execute(ctx context.Context, args map[string]any) *ToolRes
 		return &ToolResult{ForLLM: "Message sending not configured", IsError: true}
 	}
 
+	// Guard against accidental repeated tool-calls in one LLM round.
+	// If the same target and content were already sent, suppress duplicate delivery.
+	if t.sentInRound && t.lastChannel == channel && t.lastChatID == chatID && t.lastContent == content {
+		return &ToolResult{
+			ForLLM: "Duplicate message suppressed in current round",
+			Silent: true,
+		}
+	}
+
 	if err := t.sendCallback(channel, chatID, content); err != nil {
 		return &ToolResult{
 			ForLLM:  fmt.Sprintf("sending message: %v", err),
@@ -95,6 +110,9 @@ func (t *MessageTool) Execute(ctx context.Context, args map[string]any) *ToolRes
 	}
 
 	t.sentInRound = true
+	t.lastChannel = channel
+	t.lastChatID = chatID
+	t.lastContent = content
 	// Silent: user already received the message directly
 	return &ToolResult{
 		ForLLM: fmt.Sprintf("Message sent to %s:%s", channel, chatID),

pkg/tools/message_test.go

@@ -194,6 +194,38 @@ func TestMessageTool_Execute_NotConfigured(t *testing.T) {
 	}
 }
 
+func TestMessageTool_Execute_SuppressDuplicateInSameRound(t *testing.T) {
+	tool := NewMessageTool()
+	tool.SetContext("test-channel", "test-chat-id")
+
+	callCount := 0
+	tool.SetSendCallback(func(channel, chatID, content string) error {
+		callCount++
+		return nil
+	})
+
+	ctx := context.Background()
+	args := map[string]any{
+		"content": "same message",
+	}
+
+	first := tool.Execute(ctx, args)
+	second := tool.Execute(ctx, args)
+
+	if callCount != 1 {
+		t.Fatalf("send callback call count = %d, want 1", callCount)
+	}
+	if !first.Silent || first.IsError {
+		t.Fatalf("first result unexpected: %+v", first)
+	}
+	if !second.Silent || second.IsError {
+		t.Fatalf("second result unexpected: %+v", second)
+	}
+	if second.ForLLM != "Duplicate message suppressed in current round" {
+		t.Fatalf("second ForLLM = %q", second.ForLLM)
+	}
+}
+
 func TestMessageTool_Name(t *testing.T) {
 	tool := NewMessageTool()
 	if tool.Name() != "message" {