feat: add anthropic-messages protocol for native Anthropic API

- Add new 'anthropic-messages' protocol prefix to support Anthropic's native Messages API format (/v1/messages endpoint)
- Use anthropicprovider.NewProviderWithBaseURL() for native format requests
- Modify anthropicprovider to use streaming API (Messages.NewStreaming) for compatibility with services requiring streaming
- Aggregate streaming events into complete response for backward compatibility
- Update config.example.json with usage documentation
- Maintain full backward compatibility with existing 'anthropic' protocol (OpenAI-compatible /chat/completions format)

This change enables picoclaw to work with Anthropic-compatible APIs that only support the native Messages format, such as Weibo's GLM-4.7 service.

BREAKING-CHANGE: anthropicprovider now uses streaming API internally, but maintains the same interface (aggregates to complete response). This should not affect existing users.

config/config.example.json

@@ -25,6 +25,13 @@
       "api_base": "https://api.anthropic.com/v1",
       "thinking_level": "high"
     },
+    {
+      "model_name": "claude-native",
+      "model": "anthropic-messages/claude-sonnet-4.6",
+      "api_key": "sk-ant-your-key",
+      "api_base": "https://api.anthropic.com",
+      "thinking_level": "high"
+    },
     {
       "model_name": "gemini",
       "model": "antigravity/gemini-2.0-flash",

pkg/providers/anthropic/provider.go

@@ -88,12 +88,24 @@ func (p *Provider) Chat(
 		return nil, err
 	}
 
-	resp, err := p.client.Messages.New(ctx, params, opts...)
+	// 使用流式 API 以兼容要求流式请求的服务端
+	// 流式响应会被聚合为完整响应后返回
+	stream := p.client.Messages.NewStreaming(ctx, params, opts...)
+	defer stream.Close()
+
+	// 收集所有流式事件以便后续处理
+	var events []anthropic.MessageStreamEventUnion
+	for stream.Next() {
+		events = append(events, stream.Current())
+	}
+
+	err = stream.Err()
 	if err != nil {
 		return nil, fmt.Errorf("claude API call: %w", err)
 	}
 
-	return parseResponse(resp), nil
+	// 从收集的事件中提取完整的响应
+	return parseStreamingEvents(events), nil
 }
 
 func (p *Provider) GetDefaultModel() string {
@@ -336,6 +348,74 @@ func parseResponse(resp *anthropic.Message) *LLMResponse {
 	}
 }
 
+// parseStreamingEvents 从流式事件中提取完整的 Message 对象
+func parseStreamingEvents(events []anthropic.MessageStreamEventUnion) *LLMResponse {
+	var content strings.Builder
+	var reasoning strings.Builder
+	var toolCalls []ToolCall
+	var stopReason anthropic.StopReason
+	var usage anthropic.Usage
+
+	for _, evt := range events {
+		switch evt.Type {
+		case "message_start":
+			if msg := evt.AsMessageStart(); msg.Message.ID != "" {
+				usage = msg.Message.Usage
+			}
+		case "content_block_start":
+			block := evt.AsContentBlockStart()
+			switch block.ContentBlock.Type {
+			case "tool_use":
+				// 工具调用开始，在 delta 中处理
+			}
+		case "content_block_delta":
+			delta := evt.AsContentBlockDelta()
+			switch delta.Delta.Type {
+			case "thinking_delta":
+				reasoning.WriteString(delta.Delta.Thinking)
+			case "text_delta":
+				content.WriteString(delta.Delta.Text)
+			case "input_json_delta":
+				// 工具调用参数增量，需要累积
+				// TODO: 实现完整的工具调用支持
+			}
+		case "content_block_stop":
+			// 内容块结束
+		case "message_delta":
+			msgDelta := evt.AsMessageDelta()
+			stopReason = msgDelta.Delta.StopReason
+			// 更新 usage 字段
+			usage.OutputTokens = msgDelta.Usage.OutputTokens
+		case "message_stop":
+			// 消息完成
+		case "error":
+			log.Printf("anthropic: streaming error: %v", evt)
+		}
+	}
+
+	finishReason := "stop"
+	switch stopReason {
+	case anthropic.StopReasonToolUse:
+		finishReason = "tool_calls"
+	case anthropic.StopReasonMaxTokens:
+		finishReason = "length"
+	case anthropic.StopReasonEndTurn:
+		finishReason = "stop"
+	}
+
+	return &LLMResponse{
+		Content:      content.String(),
+		Reasoning:    reasoning.String(),
+		ToolCalls:    toolCalls,
+		FinishReason: finishReason,
+		Usage: &UsageInfo{
+			PromptTokens:     int(usage.InputTokens),
+			CompletionTokens: int(usage.OutputTokens),
+			TotalTokens:      int(usage.InputTokens + usage.OutputTokens),
+		},
+	}
+}
+
 func normalizeBaseURL(apiBase string) string {
 	base := strings.TrimSpace(apiBase)
 	if base == "" {

pkg/providers/factory_provider.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"github.com/sipeed/picoclaw/pkg/config"
+	anthropicprovider "github.com/sipeed/picoclaw/pkg/providers/anthropic"
 )
 
 // createClaudeAuthProvider creates a Claude provider using OAuth credentials from auth store.
@@ -136,6 +137,29 @@ func CreateProviderFromConfig(cfg *config.ModelConfig) (LLMProvider, string, err
 			cfg.RequestTimeout,
 		), modelID, nil
 
+	case "anthropic-messages":
+		// Anthropic 原生 Messages API 格式 (使用 /v1/messages 端点)
+		// 适用于需要使用 Anthropic 原生 API 格式的服务
+		if cfg.AuthMethod == "oauth" || cfg.AuthMethod == "token" {
+			// 使用 OAuth 凭据（从 auth store 获取）
+			provider, err := createClaudeAuthProvider()
+			if err != nil {
+				return nil, "", err
+			}
+			return provider, modelID, nil
+		}
+		// 使用 API key
+		if cfg.APIKey == "" {
+			return nil, "", fmt.Errorf("api_key is required for anthropic-messages protocol (model: %s)", cfg.Model)
+		}
+		apiBase := cfg.APIBase
+		if apiBase == "" {
+			apiBase = "https://api.anthropic.com"
+		}
+		// 使用 anthropicprovider 包中的原生 Anthropic provider
+		provider := anthropicprovider.NewProviderWithBaseURL(cfg.APIKey, apiBase)
+		return provider, modelID, nil
+
 	case "antigravity":
 		return NewAntigravityProvider(), modelID, nil