Merge pull request #3884 from CHOS1N11111/codex/add-parallel-tool-calls-compat

Add parallel_tool_calls compatibility mapping

backend/internal/pkg/apicompat/chatcompletions_responses_bridge.go

@@ -28,6 +28,7 @@ func ResponsesToChatCompletionsRequest(req *ResponsesRequest) (*ChatCompletionsR
 		TopP:                req.TopP,
 		Stream:              req.Stream,
 		ServiceTier:         req.ServiceTier,
+		ParallelToolCalls:   req.ParallelToolCalls,
 	}
 	if req.Reasoning != nil {
 		out.ReasoningEffort = req.Reasoning.Effort

backend/internal/pkg/apicompat/chatcompletions_responses_bridge_test.go

@@ -127,6 +127,26 @@ func TestResponsesToChatCompletionsRequest_TextFormatJsonSchema(t *testing.T) {
 	}`, string(out.ResponseFormat))
 }
 
+func TestResponsesToChatCompletionsRequest_ParallelToolCalls(t *testing.T) {
+	parallel := false
+	req := &ResponsesRequest{
+		Model: "gpt-4o",
+		Input: json.RawMessage(`[
+			{"role":"user","content":"Use tools"}
+		]`),
+		ParallelToolCalls: &parallel,
+	}
+
+	out, err := ResponsesToChatCompletionsRequest(req)
+	require.NoError(t, err)
+	require.NotNil(t, out.ParallelToolCalls)
+	assert.False(t, *out.ParallelToolCalls)
+
+	payload, err := json.Marshal(out)
+	require.NoError(t, err)
+	assert.Contains(t, string(payload), `"parallel_tool_calls":false`)
+}
+
 func chatMessageRoles(messages []ChatMessage) []string {
 	roles := make([]string, 0, len(messages))
 	for _, message := range messages {

backend/internal/pkg/apicompat/chatcompletions_responses_test.go

@@ -531,6 +531,25 @@ func TestChatCompletionsToResponses_ServiceTier(t *testing.T) {
 	assert.Equal(t, "flex", resp.ServiceTier)
 }
 
+func TestChatCompletionsToResponses_ParallelToolCalls(t *testing.T) {
+	for _, value := range []bool{false, true} {
+		req := &ChatCompletionsRequest{
+			Model:             "gpt-4o",
+			ParallelToolCalls: &value,
+			Messages:          []ChatMessage{{Role: "user", Content: json.RawMessage(`"Hi"`)}},
+		}
+
+		resp, err := ChatCompletionsToResponses(req)
+		require.NoError(t, err)
+		require.NotNil(t, resp.ParallelToolCalls)
+		assert.Equal(t, value, *resp.ParallelToolCalls)
+
+		payload, err := json.Marshal(resp)
+		require.NoError(t, err)
+		assert.Contains(t, string(payload), `"parallel_tool_calls":`+string(mustMarshalJSON(t, value)))
+	}
+}
+
 // ---------------------------------------------------------------------------
 // temperature / top_p stripping for reasoning models
 // ---------------------------------------------------------------------------

backend/internal/pkg/apicompat/chatcompletions_to_responses.go

@@ -33,6 +33,7 @@ func ChatCompletionsToResponses(req *ChatCompletionsRequest) (*ResponsesRequest,
 		Stream:            true, // upstream always streams
 		Include:           []string{"reasoning.encrypted_content"},
 		ServiceTier:       req.ServiceTier,
+		ParallelToolCalls: req.ParallelToolCalls,
 	}
 
 	// Reasoning models (gpt-5.x) do not accept sampling parameters.

backend/internal/pkg/apicompat/types.go

@@ -435,6 +435,7 @@ type ChatCompletionsRequest struct {
 	Stream              bool               `json:"stream,omitempty"`
 	StreamOptions       *ChatStreamOptions `json:"stream_options,omitempty"`
 	Tools               []ChatTool         `json:"tools,omitempty"`
+	ParallelToolCalls   *bool              `json:"parallel_tool_calls,omitempty"`
 	ToolChoice          json.RawMessage    `json:"tool_choice,omitempty"`
 	ReasoningEffort     string             `json:"reasoning_effort,omitempty"` // "low" | "medium" | "high" | "xhigh"
 	ServiceTier         string             `json:"service_tier,omitempty"`