refactor: 后端代码质量优化 - 复用公共库、使用标准库、类型安全错误判断

## 高优先级修复 - stats_service_impl: 使用 strings.SplitN 替代错误的索引分割 - provider_handler: 使用 errors.Is(err, gorm.ErrDuplicatedKey) 替代字符串匹配 - client: 重写 isNetworkError 使用 errors.As/Is 类型安全判断 - proxy_handler: 使用 encoding/json 标准库解析 JSON（extractModelName、isStreamRequest） ## 中优先级修复 - stats_handler: 添加 parseDateParam 辅助函数消除重复日期解析 - pkg/errors: 新增 ErrRequestCreate/Send/ResponseRead 错误类型和 WithCause 方法 - client: 使用结构化错误替代 fmt.Errorf - ConversionEngine: logger 依赖注入，替换所有 zap.L() 调用 ## 低优先级修复 - encoder: 删除 joinStrings，使用 strings.Join - adapter: 删除 modelInfoRegex 正则，使用 isModelInfoPath 字符串函数 ## 文档更新 - README.md: 添加公共库使用指南和编码规范章节 - specs: 同步 delta specs 到 main specs（error-handling、structured-logging、request-validation） ## 归档 - openspec/changes/archive/2026-04-20-refactor-backend-code-quality/
2026-04-20 16:42:48 +08:00
parent bc1ee612d9
commit d92db73937
35 changed files with 1493 additions and 267 deletions
--- a/backend/internal/conversion/anthropic/adapter.go
+++ b/backend/internal/conversion/anthropic/adapter.go
@@ -2,7 +2,6 @@ package anthropic

 import (
 	"encoding/json"
-	"regexp"
 	"strings"

 	"nex/backend/internal/conversion"
@@ -17,8 +16,6 @@ func NewAdapter() *Adapter {
 	return &Adapter{}
 }

-var modelInfoRegex = regexp.MustCompile(`^/v1/models/[^/]+$`)
-
 // ProtocolName 返回协议名称
 func (a *Adapter) ProtocolName() string { return "anthropic" }

@@ -35,13 +32,22 @@ func (a *Adapter) DetectInterfaceType(nativePath string) conversion.InterfaceTyp
 		return conversion.InterfaceTypeChat
 	case nativePath == "/v1/models":
 		return conversion.InterfaceTypeModels
-	case modelInfoRegex.MatchString(nativePath):
+	case isModelInfoPath(nativePath):
 		return conversion.InterfaceTypeModelInfo
 	default:
 		return conversion.InterfaceTypePassthrough
 	}
 }

+// isModelInfoPath 判断是否为模型详情路径（/v1/models/{id}）
+func isModelInfoPath(path string) bool {
+	if !strings.HasPrefix(path, "/v1/models/") {
+		return false
+	}
+	suffix := path[len("/v1/models/"):]
+	return suffix != "" && !strings.Contains(suffix, "/")
+}
+
 // BuildUrl 根据接口类型构建 URL
 func (a *Adapter) BuildUrl(nativePath string, interfaceType conversion.InterfaceType) string {
 	switch interfaceType {
--- a/backend/internal/conversion/engine.go
+++ b/backend/internal/conversion/engine.go
@@ -28,13 +28,18 @@ type HTTPResponseSpec struct {
 type ConversionEngine struct {
 	registry        AdapterRegistry
 	middlewareChain *MiddlewareChain
+	logger          *zap.Logger
 }

 // NewConversionEngine 创建转换引擎
-func NewConversionEngine(registry AdapterRegistry) *ConversionEngine {
+func NewConversionEngine(registry AdapterRegistry, logger *zap.Logger) *ConversionEngine {
+	if logger == nil {
+		logger = zap.L()
+	}
 	return &ConversionEngine{
 		registry:        registry,
 		middlewareChain: NewMiddlewareChain(),
+		logger:          logger,
 	}
 }

@@ -251,12 +256,12 @@ func (e *ConversionEngine) convertChatResponseBody(clientAdapter, providerAdapte
 func (e *ConversionEngine) convertModelsResponseBody(clientAdapter, providerAdapter ProtocolAdapter, body []byte) ([]byte, error) {
 	models, err := providerAdapter.DecodeModelsResponse(body)
 	if err != nil {
-		zap.L().Warn("解码 Models 响应失败，返回原始响应", zap.String("error", err.Error()))
+		e.logger.Warn("解码 Models 响应失败，返回原始响应", zap.String("error", err.Error()))
 		return body, nil
 	}
 	encoded, err := clientAdapter.EncodeModelsResponse(models)
 	if err != nil {
-		zap.L().Warn("编码 Models 响应失败，返回原始响应", zap.String("error", err.Error()))
+		e.logger.Warn("编码 Models 响应失败，返回原始响应", zap.String("error", err.Error()))
 		return body, nil
 	}
 	return encoded, nil
@@ -265,12 +270,12 @@ func (e *ConversionEngine) convertModelsResponseBody(clientAdapter, providerAdap
 func (e *ConversionEngine) convertModelInfoResponseBody(clientAdapter, providerAdapter ProtocolAdapter, body []byte) ([]byte, error) {
 	info, err := providerAdapter.DecodeModelInfoResponse(body)
 	if err != nil {
-		zap.L().Warn("解码 ModelInfo 响应失败，返回原始响应", zap.String("error", err.Error()))
+		e.logger.Warn("解码 ModelInfo 响应失败，返回原始响应", zap.String("error", err.Error()))
 		return body, nil
 	}
 	encoded, err := clientAdapter.EncodeModelInfoResponse(info)
 	if err != nil {
-		zap.L().Warn("编码 ModelInfo 响应失败，返回原始响应", zap.String("error", err.Error()))
+		e.logger.Warn("编码 ModelInfo 响应失败，返回原始响应", zap.String("error", err.Error()))
 		return body, nil
 	}
 	return encoded, nil
@@ -279,7 +284,7 @@ func (e *ConversionEngine) convertModelInfoResponseBody(clientAdapter, providerA
 func (e *ConversionEngine) convertEmbeddingBody(clientAdapter, providerAdapter ProtocolAdapter, provider *TargetProvider, body []byte) ([]byte, error) {
 	req, err := clientAdapter.DecodeEmbeddingRequest(body)
 	if err != nil {
-		zap.L().Warn("解码 Embedding 请求失败，返回原始请求", zap.String("error", err.Error()))
+		e.logger.Warn("解码 Embedding 请求失败，返回原始请求", zap.String("error", err.Error()))
 		return body, nil
 	}
 	return providerAdapter.EncodeEmbeddingRequest(req, provider)
@@ -288,7 +293,7 @@ func (e *ConversionEngine) convertEmbeddingBody(clientAdapter, providerAdapter P
 func (e *ConversionEngine) convertEmbeddingResponseBody(clientAdapter, providerAdapter ProtocolAdapter, body []byte) ([]byte, error) {
 	resp, err := providerAdapter.DecodeEmbeddingResponse(body)
 	if err != nil {
-		zap.L().Warn("解码 Embedding 响应失败，返回原始响应", zap.String("error", err.Error()))
+		e.logger.Warn("解码 Embedding 响应失败，返回原始响应", zap.String("error", err.Error()))
 		return body, nil
 	}
 	return clientAdapter.EncodeEmbeddingResponse(resp)
@@ -297,7 +302,7 @@ func (e *ConversionEngine) convertEmbeddingResponseBody(clientAdapter, providerA
 func (e *ConversionEngine) convertRerankBody(clientAdapter, providerAdapter ProtocolAdapter, provider *TargetProvider, body []byte) ([]byte, error) {
 	req, err := clientAdapter.DecodeRerankRequest(body)
 	if err != nil {
-		zap.L().Warn("解码 Rerank 请求失败，返回原始请求", zap.String("error", err.Error()))
+		e.logger.Warn("解码 Rerank 请求失败，返回原始请求", zap.String("error", err.Error()))
 		return body, nil
 	}
 	return providerAdapter.EncodeRerankRequest(req, provider)
--- a/backend/internal/conversion/engine_supplemental_test.go
+++ b/backend/internal/conversion/engine_supplemental_test.go
@@ -39,7 +39,7 @@ func TestConversionError_FullBuilder(t *testing.T) {

 func TestEngine_Use(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	called := false
 	engine.Use(&testMiddleware{fn: func(req *canonical.CanonicalRequest, cp, pp string, ctx *ConversionContext) (*canonical.CanonicalRequest, error) {
 		called = true
@@ -66,7 +66,7 @@ func TestEngine_Use(t *testing.T) {

 func TestConvertHttpRequest_DecodeError(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	clientAdapter := newMockAdapter("client", false)
 	clientAdapter.decodeReqFn = func(raw []byte) (*canonical.CanonicalRequest, error) {
 		return nil, errors.New("decode failed")
@@ -82,7 +82,7 @@ func TestConvertHttpRequest_DecodeError(t *testing.T) {

 func TestConvertHttpRequest_EncodeError(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	_ = engine.RegisterAdapter(newMockAdapter("client", false))
 	providerAdapter := newMockAdapter("provider", false)
 	providerAdapter.encodeReqFn = func(req *canonical.CanonicalRequest, p *TargetProvider) ([]byte, error) {
@@ -98,7 +98,7 @@ func TestConvertHttpRequest_EncodeError(t *testing.T) {

 func TestConvertHttpResponse_CrossProtocol(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)

 	clientAdapter := newMockAdapter("client", false)
 	clientAdapter.encodeRespFn = func(resp *canonical.CanonicalResponse) ([]byte, error) {
@@ -121,7 +121,7 @@ func TestConvertHttpResponse_CrossProtocol(t *testing.T) {

 func TestConvertHttpResponse_DecodeError(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	providerAdapter := newMockAdapter("provider", false)
 	providerAdapter.decodeRespFn = func(raw []byte) (*canonical.CanonicalResponse, error) {
 		return nil, errors.New("decode error")
@@ -135,7 +135,7 @@ func TestConvertHttpResponse_DecodeError(t *testing.T) {

 func TestConvertHttpRequest_EmbeddingInterface(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)

 	clientAdapter := newMockAdapter("client", false)
 	clientAdapter.ifaceType = InterfaceTypeEmbeddings
@@ -158,7 +158,7 @@ func TestConvertHttpRequest_EmbeddingInterface(t *testing.T) {

 func TestConvertHttpRequest_RerankInterface(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)

 	clientAdapter := newMockAdapter("client", false)
 	clientAdapter.ifaceType = InterfaceTypeRerank
@@ -178,7 +178,7 @@ func TestConvertHttpRequest_RerankInterface(t *testing.T) {

 func TestConvertHttpResponse_EmbeddingInterface(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)

 	clientAdapter := newMockAdapter("client", false)
 	clientAdapter.supportsIface = map[InterfaceType]bool{InterfaceTypeEmbeddings: true}
@@ -196,7 +196,7 @@ func TestConvertHttpResponse_EmbeddingInterface(t *testing.T) {

 func TestConvertHttpResponse_RerankInterface(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)

 	clientAdapter := newMockAdapter("client", false)
 	clientAdapter.supportsIface = map[InterfaceType]bool{InterfaceTypeRerank: true}
@@ -214,7 +214,7 @@ func TestConvertHttpResponse_RerankInterface(t *testing.T) {

 func TestConvertHttpRequest_ModelsInterface_Passthrough(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	clientAdapter := newMockAdapter("client", false)
 	clientAdapter.ifaceType = InterfaceTypeModels
 	providerAdapter := newMockAdapter("provider", false)
@@ -232,7 +232,7 @@ func TestConvertHttpRequest_ModelsInterface_Passthrough(t *testing.T) {

 func TestConvertHttpResponse_ModelsInterface(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	clientAdapter := newMockAdapter("client", false)
 	clientAdapter.supportsIface = map[InterfaceType]bool{InterfaceTypeModels: true}
 	providerAdapter := newMockAdapter("provider", false)
@@ -249,7 +249,7 @@ func TestConvertHttpResponse_ModelsInterface(t *testing.T) {

 func TestConvertHttpResponse_ModelInfoInterface(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	clientAdapter := newMockAdapter("client", false)
 	clientAdapter.supportsIface = map[InterfaceType]bool{InterfaceTypeModelInfo: true}
 	providerAdapter := newMockAdapter("provider", false)
--- a/backend/internal/conversion/engine_test.go
+++ b/backend/internal/conversion/engine_test.go
@@ -8,6 +8,7 @@ import (

 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"go.uber.org/zap"
 )

 // mockProtocolAdapter 模拟协议适配器
@@ -170,14 +171,29 @@ func (e *noopStreamEncoder) Flush() [][]byte

 func TestNewConversionEngine(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	assert.NotNil(t, engine)
 	assert.Equal(t, registry, engine.GetRegistry())
 }

+func TestNewConversionEngine_LoggerInjection(t *testing.T) {
+	t.Run("nil_logger_uses_global", func(t *testing.T) {
+		registry := NewMemoryRegistry()
+		engine := NewConversionEngine(registry, nil)
+		assert.NotNil(t, engine.logger)
+	})
+
+	t.Run("custom_logger", func(t *testing.T) {
+		registry := NewMemoryRegistry()
+		customLogger := zap.NewNop()
+		engine := NewConversionEngine(registry, customLogger)
+		assert.Equal(t, customLogger, engine.logger)
+	})
+}
+
 func TestRegisterAdapter(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)

 	adapter := newMockAdapter("test-proto", true)
 	err := engine.RegisterAdapter(adapter)
@@ -189,7 +205,7 @@ func TestRegisterAdapter(t *testing.T) {

 func TestIsPassthrough_SameProtocol(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	adapter := newMockAdapter("openai", true)
 	_ = engine.RegisterAdapter(adapter)

@@ -198,7 +214,7 @@ func TestIsPassthrough_SameProtocol(t *testing.T) {

 func TestIsPassthrough_DifferentProtocol(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	_ = engine.RegisterAdapter(newMockAdapter("openai", true))
 	_ = engine.RegisterAdapter(newMockAdapter("anthropic", true))

@@ -207,7 +223,7 @@ func TestIsPassthrough_DifferentProtocol(t *testing.T) {

 func TestIsPassthrough_NoPassthrough(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	_ = engine.RegisterAdapter(newMockAdapter("custom", false))

 	assert.False(t, engine.IsPassthrough("custom", "custom"))
@@ -215,7 +231,7 @@ func TestIsPassthrough_NoPassthrough(t *testing.T) {

 func TestDetectInterfaceType(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	adapter := newMockAdapter("test", true)
 	adapter.ifaceType = InterfaceTypeChat
 	_ = engine.RegisterAdapter(adapter)
@@ -227,7 +243,7 @@ func TestDetectInterfaceType(t *testing.T) {

 func TestDetectInterfaceType_NonExistentProtocol(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)

 	_, err := engine.DetectInterfaceType("/v1/chat", "nonexistent")
 	assert.Error(t, err)
@@ -235,7 +251,7 @@ func TestDetectInterfaceType_NonExistentProtocol(t *testing.T) {

 func TestConvertHttpRequest_Passthrough(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	_ = engine.RegisterAdapter(newMockAdapter("openai", true))

 	provider := NewTargetProvider("https://api.openai.com", "sk-test", "gpt-4")
@@ -253,7 +269,7 @@ func TestConvertHttpRequest_Passthrough(t *testing.T) {

 func TestConvertHttpRequest_CrossProtocol(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)

 	clientAdapter := newMockAdapter("client-proto", false)
 	clientAdapter.decodeReqFn = func(raw []byte) (*canonical.CanonicalRequest, error) {
@@ -285,7 +301,7 @@ func TestConvertHttpRequest_CrossProtocol(t *testing.T) {

 func TestConvertHttpResponse_Passthrough(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	_ = engine.RegisterAdapter(newMockAdapter("openai", true))

 	spec := HTTPResponseSpec{
@@ -301,7 +317,7 @@ func TestConvertHttpResponse_Passthrough(t *testing.T) {

 func TestCreateStreamConverter_Passthrough(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	_ = engine.RegisterAdapter(newMockAdapter("openai", true))

 	converter, err := engine.CreateStreamConverter("openai", "openai")
@@ -312,7 +328,7 @@ func TestCreateStreamConverter_Passthrough(t *testing.T) {

 func TestCreateStreamConverter_Canonical(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	_ = engine.RegisterAdapter(newMockAdapter("client", false))
 	_ = engine.RegisterAdapter(newMockAdapter("provider", false))

@@ -324,7 +340,7 @@ func TestCreateStreamConverter_Canonical(t *testing.T) {

 func TestEncodeError(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)
 	_ = engine.RegisterAdapter(newMockAdapter("openai", true))

 	convErr := NewConversionError(ErrorCodeInvalidInput, "测试错误")
@@ -336,7 +352,7 @@ func TestEncodeError(t *testing.T) {

 func TestEncodeError_NonExistentProtocol(t *testing.T) {
 	registry := NewMemoryRegistry()
-	engine := NewConversionEngine(registry)
+	engine := NewConversionEngine(registry, nil)

 	convErr := NewConversionError(ErrorCodeInvalidInput, "测试错误")
 	body, statusCode, err := engine.EncodeError(convErr, "nonexistent")
--- a/backend/internal/conversion/openai/adapter.go
+++ b/backend/internal/conversion/openai/adapter.go
@@ -2,7 +2,7 @@ package openai

 import (
 	"encoding/json"
-	"regexp"
+	"strings"

 	"nex/backend/internal/conversion"
 	"nex/backend/internal/conversion/canonical"
@@ -16,8 +16,6 @@ func NewAdapter() *Adapter {
 	return &Adapter{}
 }

-var modelInfoRegex = regexp.MustCompile(`^/v1/models/[^/]+$`)
-
 // ProtocolName 返回协议名称
 func (a *Adapter) ProtocolName() string { return "openai" }

@@ -34,7 +32,7 @@ func (a *Adapter) DetectInterfaceType(nativePath string) conversion.InterfaceTyp
 		return conversion.InterfaceTypeChat
 	case nativePath == "/v1/models":
 		return conversion.InterfaceTypeModels
-	case modelInfoRegex.MatchString(nativePath):
+	case isModelInfoPath(nativePath):
 		return conversion.InterfaceTypeModelInfo
 	case nativePath == "/v1/embeddings":
 		return conversion.InterfaceTypeEmbeddings
@@ -45,6 +43,15 @@ func (a *Adapter) DetectInterfaceType(nativePath string) conversion.InterfaceTyp
 	}
 }

+// isModelInfoPath 判断是否为模型详情路径（/v1/models/{id}）
+func isModelInfoPath(path string) bool {
+	if !strings.HasPrefix(path, "/v1/models/") {
+		return false
+	}
+	suffix := path[len("/v1/models/"):]
+	return suffix != "" && !strings.Contains(suffix, "/")
+}
+
 // BuildUrl 根据接口类型构建 URL
 func (a *Adapter) BuildUrl(nativePath string, interfaceType conversion.InterfaceType) string {
 	switch interfaceType {
--- a/backend/internal/conversion/openai/adapter_test.go
+++ b/backend/internal/conversion/openai/adapter_test.go
@@ -112,6 +112,28 @@ func TestAdapter_SupportsInterface(t *testing.T) {
 	}
 }

+func TestIsModelInfoPath(t *testing.T) {
+	tests := []struct {
+		name     string
+		path     string
+		expected bool
+	}{
+		{"model_info", "/v1/models/gpt-4", true},
+		{"model_info_with_dots", "/v1/models/gpt-4.1-preview", true},
+		{"models_list", "/v1/models", false},
+		{"nested_path", "/v1/models/gpt-4/versions", false},
+		{"empty_suffix", "/v1/models/", false},
+		{"unrelated", "/v1/chat/completions", false},
+		{"partial_prefix", "/v1/model", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.expected, isModelInfoPath(tt.path))
+		})
+	}
+}
+
 func TestAdapter_EncodeError_InvalidInput(t *testing.T) {
 	a := NewAdapter()
 	convErr := conversion.NewConversionError(conversion.ErrorCodeInvalidInput, "参数无效")
--- a/backend/internal/conversion/openai/encoder.go
+++ b/backend/internal/conversion/openai/encoder.go
@@ -2,6 +2,7 @@ package openai

 import (
 	"encoding/json"
+	"strings"
 	"time"

 	"nex/backend/internal/conversion"
@@ -89,7 +90,7 @@ func encodeSystemAndMessages(req *canonical.CanonicalRequest) []map[string]any {
 		for _, b := range v {
 			parts = append(parts, b.Text)
 		}
-		text := joinStrings(parts, "\n\n")
+		text := strings.Join(parts, "\n\n")
 		if text != "" {
 			messages = append(messages, map[string]any{
 				"role":    "system",
@@ -132,7 +133,7 @@ func encodeMessage(msg canonical.CanonicalMessage) []map[string]any {

 		if len(toolUses) > 0 {
 			if len(textParts) > 0 {
-				m["content"] = joinStrings(textParts, "")
+				m["content"] = strings.Join(textParts, "")
 			} else {
 				m["content"] = nil
 			}
@@ -149,7 +150,7 @@ func encodeMessage(msg canonical.CanonicalMessage) []map[string]any {
 			}
 			m["tool_calls"] = tcs
 		} else if len(textParts) > 0 {
-			m["content"] = joinStrings(textParts, "")
+			m["content"] = strings.Join(textParts, "")
 		} else {
 			m["content"] = ""
 		}
@@ -286,7 +287,7 @@ func encodeResponse(resp *canonical.CanonicalResponse) ([]byte, error) {
 	message := map[string]any{"role": "assistant"}
 	if len(toolUses) > 0 {
 		if len(textParts) > 0 {
-			message["content"] = joinStrings(textParts, "")
+			message["content"] = strings.Join(textParts, "")
 		} else {
 			message["content"] = nil
 		}
@@ -303,13 +304,13 @@ func encodeResponse(resp *canonical.CanonicalResponse) ([]byte, error) {
 		}
 		message["tool_calls"] = tcs
 	} else if len(textParts) > 0 {
-		message["content"] = joinStrings(textParts, "")
+		message["content"] = strings.Join(textParts, "")
 	} else {
 		message["content"] = ""
 	}

 	if len(thinkingParts) > 0 {
-		message["reasoning_content"] = joinStrings(thinkingParts, "")
+		message["reasoning_content"] = strings.Join(thinkingParts, "")
 	}

 	var finishReason *string
@@ -488,18 +489,6 @@ func encodeRerankResponse(resp *canonical.CanonicalRerankResponse) ([]byte, erro
 	})
 }

-// joinStrings 拼接字符串切片
-func joinStrings(parts []string, sep string) string {
-	result := ""
-	for i, p := range parts {
-		if i > 0 {
-			result += sep
-		}
-		result += p
-	}
-	return result
-}
-
 // mergeConsecutiveRoles 合并连续同角色消息（拼接内容）
 func mergeConsecutiveRoles(messages []map[string]any) []map[string]any {
 	if len(messages) <= 1 {