feat: Hide raw tool call JSON from output_text in OpenAI-style responses when structured tool calls are present.

internal/util/render.go

@@ -43,8 +43,12 @@ func BuildOpenAIChatCompletion(completionID, model, finalPrompt, finalThinking,
 
 func BuildOpenAIResponseObject(responseID, model, finalPrompt, finalThinking, finalText string, toolNames []string) map[string]any {
 	detected := ParseToolCalls(finalText, toolNames)
+	exposedOutputText := finalText
 	output := make([]any, 0, 2)
 	if len(detected) > 0 {
+		// Keep structured tool output only; avoid leaking raw tool-call JSON
+		// into response.output_text for clients reading completed responses.
+		exposedOutputText = ""
 		toolCalls := make([]any, 0, len(detected))
 		for _, tc := range detected {
 			toolCalls = append(toolCalls, map[string]any{
@@ -88,7 +92,7 @@ func BuildOpenAIResponseObject(responseID, model, finalPrompt, finalThinking, fi
 		"status":      "completed",
 		"model":       model,
 		"output":      output,
-		"output_text": finalText,
+		"output_text": exposedOutputText,
 		"usage": map[string]any{
 			"input_tokens":  promptTokens,
 			"output_tokens": reasoningTokens + completionTokens,

internal/util/render_test.go

@@ -54,6 +54,28 @@ func TestBuildOpenAIResponseObjectWithText(t *testing.T) {
 	}
 }
 
+func TestBuildOpenAIResponseObjectToolCallsHidesRawOutputText(t *testing.T) {
+	out := BuildOpenAIResponseObject(
+		"resp_2",
+		"gpt-4o",
+		"prompt",
+		"",
+		`{"tool_calls":[{"name":"search","input":{"q":"go"}}]}`,
+		[]string{"search"},
+	)
+	if out["output_text"] != "" {
+		t.Fatalf("expected empty output_text for tool_calls, got %#v", out["output_text"])
+	}
+	output, _ := out["output"].([]any)
+	if len(output) == 0 {
+		t.Fatalf("expected output entries")
+	}
+	first, _ := output[0].(map[string]any)
+	if first["type"] != "tool_calls" {
+		t.Fatalf("expected first output type tool_calls, got %#v", first["type"])
+	}
+}
+
 func TestBuildClaudeMessageResponseToolUse(t *testing.T) {
 	out := BuildClaudeMessageResponse(
 		"msg_1",