fix(relay):修复Chat→Claude 转换时无参数工具缺 input_schema

relaykit/relayconvert/internal/oai_chat/claude_to_openai_request.go

@@ -97,7 +97,10 @@ func (c *ClaudeToOpenAIRequestConverter) ConvertRequest(
 		openaiReq.WebSearchOptions = spec.ToOpenAIOptions()
 	}
 
-	if claudeReq.ToolChoice != nil {
+	// tool_choice 依附于 tools：内置工具被过滤后 tools 可能为空（如客户端只带 web_search），
+	// 此时残留的 tool_choice 会形成「有 tool_choice 无 tools」的孤儿请求体，OpenAI 同样拒绝。
+	// 与 o2c 方向对称处理。
+	if claudeReq.ToolChoice != nil && len(openaiReq.Tools) > 0 {
 		openaiReq.ToolChoice = c2oConvertToolChoice(claudeReq.ToolChoice)
 	}
 

relaykit/relayconvert/internal/oai_chat/claude_to_openai_request_test.go

@@ -430,3 +430,32 @@ func TestConvertClaudeAssistantMessage(t *testing.T) {
 		t.Errorf("arguments = %q", tc.Function.Arguments)
 	}
 }
+
+// Claude 侧只带服务端内置工具（web_search）时，函数工具列表为空，
+// tool_choice 必须一并丢弃——OpenAI 同样拒绝「有 tool_choice 无 tools」的请求体。
+func TestClaudeToOpenAIRequestConverter_BuiltinOnlyToolsDropsToolChoice(t *testing.T) {
+	converter := &ClaudeToOpenAIRequestConverter{}
+	claudeReq := &dto.ClaudeRequest{
+		Model:      "claude-sonnet-4",
+		Tools:      []dto.ClaudeTool{{Type: "web_search_20250305", Name: "web_search"}},
+		ToolChoice: map[string]any{"type": "any"},
+		Messages:   []dto.ClaudeMessage{{Role: "user", Content: "搜一下"}},
+	}
+
+	result, err := converter.ConvertRequest(context.Background(), newClaudeInboundMeta(), claudeReq)
+	if err != nil {
+		t.Fatalf("ConvertRequest error: %v", err)
+	}
+	openaiReq := result.(*dto.GeneralOpenAIRequest)
+
+	if len(openaiReq.Tools) != 0 {
+		t.Errorf("Tools = %+v, want empty", openaiReq.Tools)
+	}
+	if openaiReq.ToolChoice != nil {
+		t.Errorf("ToolChoice = %v, want nil without tools", openaiReq.ToolChoice)
+	}
+	// 搜索能力本身不能丢：走 web_search_options 承载
+	if openaiReq.WebSearchOptions == nil {
+		t.Error("WebSearchOptions is nil, web search capability lost")
+	}
+}

relaykit/relayconvert/internal/oai_chat/openai_to_claude_request.go

@@ -153,9 +153,11 @@ func (c *OpenAIToClaudeRequestConverter) ConvertRequest(
 		claudeReq.System = strings.Join(systemPrompts, "\n\n")
 	}
 
-	// 转换 tools
-	if len(openaiReq.Tools) > 0 {
-		claudeReq.Tools = shared.MapOpenAIToolsToClaudeTools(openaiReq.Tools)
+	// 转换 tools。非 function 类型（如 OpenAI 的 custom 自由格式工具）会被过滤掉，
+	// 过滤后可能为空——此时 tool_choice 必须一并跳过：tools 空数组本身由 omitempty 省略，
+	// 但残留的 tool_choice 会形成「有 tool_choice 无 tools」的孤儿请求体，被 Claude 拒绝。
+	if claudeTools := shared.MapOpenAIToolsToClaudeTools(openaiReq.Tools); len(claudeTools) > 0 {
+		claudeReq.Tools = claudeTools
 		// 转换 tool_choice
 		if openaiReq.ToolChoice != nil {
 			switch tc := openaiReq.ToolChoice.(type) {

relaykit/relayconvert/internal/oai_chat/openai_to_claude_request_test.go

@@ -565,3 +565,78 @@ func TestOpenAIToClaudeRequestConverter_WebSearchOptions(t *testing.T) {
 		t.Errorf("web_search_options 应还原为 claude 原生 web_search 工具，实际 tools: %+v", claudeReq.Tools)
 	}
 }
+
+// 无参函数工具转换后必须携带 input_schema：Claude 的 custom tool 要求该字段必填。
+func TestOpenAIToClaudeRequestConverter_ToolWithoutParameters(t *testing.T) {
+	converter := &OpenAIToClaudeRequestConverter{}
+	maxTokens := 1024
+	openaiReq := &dto.GeneralOpenAIRequest{
+		Model:     "gpt-4",
+		MaxTokens: &maxTokens,
+		Messages:  []dto.Message{{Role: "user", Content: "现在几点"}},
+		Tools: []dto.Tool{{
+			Type:     "function",
+			Function: dto.FunctionDef{Name: "get_current_time", Description: "无参数"},
+		}},
+	}
+
+	result, err := converter.ConvertRequest(context.Background(), &mockMeta{upstreamModel: "claude-3-opus-20240229"}, openaiReq)
+	if err != nil {
+		t.Fatalf("ConvertRequest error: %v", err)
+	}
+
+	data, err := json.Marshal(result)
+	if err != nil {
+		t.Fatalf("Marshal failed: %v", err)
+	}
+
+	var body struct {
+		Tools []map[string]any `json:"tools"`
+	}
+	if err := json.Unmarshal(data, &body); err != nil {
+		t.Fatalf("Unmarshal failed: %v", err)
+	}
+
+	if len(body.Tools) != 1 {
+		t.Fatalf("got %d tools, want 1: %s", len(body.Tools), data)
+	}
+	if _, ok := body.Tools[0]["input_schema"]; !ok {
+		t.Errorf("input_schema missing in %s", data)
+	}
+}
+
+// 工具全部为非 function 类型时被过滤空，tools 与 tool_choice 都不得出现在请求体中：
+// 只发 tool_choice 会形成孤儿字段，被 Claude 拒绝。
+func TestOpenAIToClaudeRequestConverter_AllToolsFilteredDropsToolChoice(t *testing.T) {
+	converter := &OpenAIToClaudeRequestConverter{}
+	maxTokens := 1024
+	openaiReq := &dto.GeneralOpenAIRequest{
+		Model:      "gpt-4",
+		MaxTokens:  &maxTokens,
+		Messages:   []dto.Message{{Role: "user", Content: "hi"}},
+		Tools:      []dto.Tool{{Type: "custom", Function: dto.FunctionDef{Name: "freeform"}}},
+		ToolChoice: "required",
+	}
+
+	result, err := converter.ConvertRequest(context.Background(), &mockMeta{upstreamModel: "claude-3-opus-20240229"}, openaiReq)
+	if err != nil {
+		t.Fatalf("ConvertRequest error: %v", err)
+	}
+
+	data, err := json.Marshal(result)
+	if err != nil {
+		t.Fatalf("Marshal failed: %v", err)
+	}
+
+	var body map[string]any
+	if err := json.Unmarshal(data, &body); err != nil {
+		t.Fatalf("Unmarshal failed: %v", err)
+	}
+
+	if _, ok := body["tools"]; ok {
+		t.Errorf("tools should be absent, got %s", data)
+	}
+	if _, ok := body["tool_choice"]; ok {
+		t.Errorf("tool_choice should be absent without tools, got %s", data)
+	}
+}

relaykit/relayconvert/internal/shared/tool_mapper.go

@@ -20,9 +20,16 @@ func MapOpenAIToolsToClaudeTools(tools []dto.Tool) []dto.ClaudeTool {
 			Description: tool.Function.Description,
 		}
 
-		// 转换参数（JSON Schema）
+		// 转换参数（JSON Schema）。Claude 要求 custom tool 必须携带 input_schema，
+		// 而 OpenAI 允许无参函数省略 parameters——缺省时补一个空对象 schema，
+		// 否则 InputSchema 为 nil 被 omitempty 抹掉，上游直接 400。
 		if tool.Function.Parameters != nil {
 			claudeTool.InputSchema = tool.Function.Parameters
+		} else {
+			claudeTool.InputSchema = map[string]any{
+				"type":       "object",
+				"properties": map[string]any{},
+			}
 		}
 
 		claudeTools = append(claudeTools, claudeTool)

relaykit/relayconvert/internal/shared/tool_mapper_test.go

@@ -149,3 +149,62 @@ func TestMapOpenAIToolCallsToClaude(t *testing.T) {
 		t.Errorf("Expected location 'San Francisco', got %v", input["location"])
 	}
 }
+
+// 无参函数（OpenAI 允许省略 parameters）必须补出空对象 schema：
+// Claude 的 custom tool 要求 input_schema 必填，缺失会被上游以 400 拒绝。
+func TestMapOpenAIToolsToClaudeTools_NoParameters(t *testing.T) {
+	tools := []dto.Tool{
+		{
+			Type: "function",
+			Function: dto.FunctionDef{
+				Name:        "get_current_time",
+				Description: "No arguments needed",
+			},
+		},
+	}
+
+	result := MapOpenAIToolsToClaudeTools(tools)
+
+	if len(result) != 1 {
+		t.Fatalf("Expected 1 tool, got %d", len(result))
+	}
+
+	if result[0].InputSchema == nil {
+		t.Fatal("InputSchema is nil, expected empty object schema")
+	}
+
+	// 序列化后必须带 input_schema 键（omitempty 不能把它抹掉）
+	data, err := json.Marshal(result[0])
+	if err != nil {
+		t.Fatalf("Marshal failed: %v", err)
+	}
+
+	var decoded map[string]any
+	if err := json.Unmarshal(data, &decoded); err != nil {
+		t.Fatalf("Unmarshal failed: %v", err)
+	}
+
+	schema, ok := decoded["input_schema"].(map[string]any)
+	if !ok {
+		t.Fatalf("input_schema missing or wrong type in %s", data)
+	}
+
+	if schema["type"] != "object" {
+		t.Errorf("input_schema.type = %v, want object", schema["type"])
+	}
+
+	if _, ok := schema["properties"].(map[string]any); !ok {
+		t.Errorf("input_schema.properties missing in %s", data)
+	}
+}
+
+// 非 function 类型的工具被过滤后返回空 slice，调用方据此判空。
+func TestMapOpenAIToolsToClaudeTools_AllFiltered(t *testing.T) {
+	tools := []dto.Tool{
+		{Type: "custom", Function: dto.FunctionDef{Name: "freeform"}},
+	}
+
+	if result := MapOpenAIToolsToClaudeTools(tools); len(result) != 0 {
+		t.Errorf("Expected 0 tools, got %d", len(result))
+	}
+}