fix(anthropic): support Claude 4.x models and mixed-content tool calls

llms/anthropic/anthropicllm.go

@@ -384,34 +384,41 @@ func handleHumanMessage(msg llms.MessageContent) (anthropicclient.ChatMessage, e
 }
 
 func handleAIMessage(msg llms.MessageContent) (anthropicclient.ChatMessage, error) {
-	if toolCall, ok := msg.Parts[0].(llms.ToolCall); ok {
-		var inputStruct map[string]interface{}
-		err := json.Unmarshal([]byte(toolCall.FunctionCall.Arguments), &inputStruct)
-		if err != nil {
-			return anthropicclient.ChatMessage{}, fmt.Errorf("anthropic: failed to unmarshal tool call arguments: %w", err)
-		}
-		toolUse := anthropicclient.ToolUseContent{
-			Type:  "tool_use",
-			ID:    toolCall.ID,
-			Name:  toolCall.FunctionCall.Name,
-			Input: inputStruct,
-		}
+	var contents []anthropicclient.Content
 
-		return anthropicclient.ChatMessage{
-			Role:    RoleAssistant,
-			Content: []anthropicclient.Content{toolUse},
-		}, nil
+	for _, part := range msg.Parts {
+		switch p := part.(type) {
+		case llms.ToolCall:
+			var inputStruct map[string]interface{}
+			if err := json.Unmarshal([]byte(p.FunctionCall.Arguments), &inputStruct); err != nil {
+				return anthropicclient.ChatMessage{}, fmt.Errorf("anthropic: failed to unmarshal tool call arguments: %w", err)
+			}
+			contents = append(contents, anthropicclient.ToolUseContent{
+				Type:  "tool_use",
+				ID:    p.ID,
+				Name:  p.FunctionCall.Name,
+				Input: inputStruct,
+			})
+		case llms.TextContent:
+			if p.Text != "" {
+				contents = append(contents, &anthropicclient.TextContent{
+					Type: "text",
+					Text: p.Text,
+				})
+			}
+		default:
+			return anthropicclient.ChatMessage{}, fmt.Errorf("anthropic: %w for AI message part type %T", ErrInvalidContentType, part)
+		}
 	}
-	if textContent, ok := msg.Parts[0].(llms.TextContent); ok {
-		return anthropicclient.ChatMessage{
-			Role: RoleAssistant,
-			Content: []anthropicclient.Content{&anthropicclient.TextContent{
-				Type: "text",
-				Text: textContent.Text,
-			}},
-		}, nil
+
+	if len(contents) == 0 {
+		return anthropicclient.ChatMessage{}, fmt.Errorf("anthropic: no valid content in AI message")
 	}
-	return anthropicclient.ChatMessage{}, fmt.Errorf("anthropic: %w for AI message", ErrInvalidContentType)
+
+	return anthropicclient.ChatMessage{
+		Role:    RoleAssistant,
+		Content: contents,
+	}, nil
 }
 
 type ToolResult struct {

llms/anthropic/internal/anthropicclient/anthropicclient.go

@@ -130,7 +130,7 @@ type MessageRequest struct {
 	Model       string        `json:"model"`
 	Messages    []ChatMessage `json:"messages"`
 	System      string        `json:"system,omitempty"`
-	Temperature float64       `json:"temperature"`
+	Temperature float64       `json:"temperature,omitempty"`
 	MaxTokens   int           `json:"max_tokens,omitempty"`
 	TopP        float64       `json:"top_p,omitempty"`
 	Tools       []Tool        `json:"tools,omitempty"`
@@ -142,7 +142,7 @@ type MessageRequest struct {
 
 	// BetaHeaders are additional beta feature headers to include
 	BetaHeaders            []string                                                      `json:"-"`
-	StreamingFunc          func(ctx context.Context, chunk []byte) error                `json:"-"`
+	StreamingFunc          func(ctx context.Context, chunk []byte) error                 `json:"-"`
 	StreamingReasoningFunc func(ctx context.Context, reasoningChunk, chunk []byte) error `json:"-"`
 }
 

llms/anthropic/internal/anthropicclient/messages.go

@@ -40,14 +40,14 @@ type messagePayload struct {
 	MaxTokens   int           `json:"max_tokens,omitempty"`
 	StopWords   []string      `json:"stop_sequences,omitempty"`
 	Stream      bool          `json:"stream,omitempty"`
-	Temperature float64       `json:"temperature"`
+	Temperature float64       `json:"temperature,omitempty"`
 	Tools       []Tool        `json:"tools,omitempty"`
 	TopP        float64       `json:"top_p,omitempty"`
 
 	// Extended thinking parameters (Claude 3.7+)
 	Thinking *ThinkingConfig `json:"thinking,omitempty"`
 
-	StreamingFunc          func(ctx context.Context, chunk []byte) error                      `json:"-"`
+	StreamingFunc          func(ctx context.Context, chunk []byte) error                 `json:"-"`
 	StreamingReasoningFunc func(ctx context.Context, reasoningChunk, chunk []byte) error `json:"-"`
 }