feat: Improve OpenAI tool call handling by passing unknown tool calls as content and filtering streamed tool calls by schema.

internal/format/openai/render_responses.go

@@ -27,12 +27,7 @@ func BuildResponseObject(responseID, model, finalPrompt, finalThinking, finalTex
 				"text": finalThinking,
 			})
 		}
-		formatted := util.FormatOpenAIToolCalls(detected)
-		output = append(output, toResponsesFunctionCallItems(formatted)...)
-		output = append(output, map[string]any{
-			"type":       "tool_calls",
-			"tool_calls": formatted,
-		})
+		output = append(output, toResponsesFunctionCallItems(detected)...)
 	} else {
 		content := make([]any, 0, 2)
 		if finalThinking != "" {
@@ -70,32 +65,23 @@ func BuildResponseObject(responseID, model, finalPrompt, finalThinking, finalTex
 	}
 }
 
-func toResponsesFunctionCallItems(toolCalls []map[string]any) []any {
+func toResponsesFunctionCallItems(toolCalls []util.ParsedToolCall) []any {
 	if len(toolCalls) == 0 {
 		return nil
 	}
 	out := make([]any, 0, len(toolCalls))
 	for _, tc := range toolCalls {
-		callID, _ := tc["id"].(string)
-		if strings.TrimSpace(callID) == "" {
-			callID = "call_" + strings.ReplaceAll(uuid.NewString(), "-", "")
-		}
-		name := ""
-		args := "{}"
-		if fn, ok := tc["function"].(map[string]any); ok {
-			if n, _ := fn["name"].(string); strings.TrimSpace(n) != "" {
-				name = n
-			}
-			if a, _ := fn["arguments"].(string); strings.TrimSpace(a) != "" {
-				args = a
-			}
+		if strings.TrimSpace(tc.Name) == "" {
+			continue
 		}
+		argsBytes, _ := json.Marshal(tc.Input)
+		args := normalizeJSONString(string(argsBytes))
 		out = append(out, map[string]any{
 			"id":        "fc_" + strings.ReplaceAll(uuid.NewString(), "-", ""),
 			"type":      "function_call",
-			"call_id":   callID,
-			"name":      name,
-			"arguments": normalizeJSONString(args),
+			"call_id":   "call_" + strings.ReplaceAll(uuid.NewString(), "-", ""),
+			"name":      tc.Name,
+			"arguments": args,
 			"status":    "completed",
 		})
 	}

internal/format/openai/render_stream_events.go

@@ -1,5 +1,7 @@
 package openai
 
+import "strings"
+
 func BuildResponsesCreatedPayload(responseID, model string) map[string]any {
 	return map[string]any{
 		"type":        "response.created",
@@ -11,6 +13,52 @@ func BuildResponsesCreatedPayload(responseID, model string) map[string]any {
 	}
 }
 
+func BuildResponsesOutputItemAddedPayload(responseID, itemID string, outputIndex int, item map[string]any) map[string]any {
+	return map[string]any{
+		"type":         "response.output_item.added",
+		"id":           responseID,
+		"response_id":  responseID,
+		"output_index": outputIndex,
+		"item_id":      itemID,
+		"item":         item,
+	}
+}
+
+func BuildResponsesOutputItemDonePayload(responseID, itemID string, outputIndex int, item map[string]any) map[string]any {
+	return map[string]any{
+		"type":         "response.output_item.done",
+		"id":           responseID,
+		"response_id":  responseID,
+		"output_index": outputIndex,
+		"item_id":      itemID,
+		"item":         item,
+	}
+}
+
+func BuildResponsesContentPartAddedPayload(responseID, itemID string, outputIndex, contentIndex int, part map[string]any) map[string]any {
+	return map[string]any{
+		"type":          "response.content_part.added",
+		"id":            responseID,
+		"response_id":   responseID,
+		"item_id":       itemID,
+		"output_index":  outputIndex,
+		"content_index": contentIndex,
+		"part":          part,
+	}
+}
+
+func BuildResponsesContentPartDonePayload(responseID, itemID string, outputIndex, contentIndex int, part map[string]any) map[string]any {
+	return map[string]any{
+		"type":          "response.content_part.done",
+		"id":            responseID,
+		"response_id":   responseID,
+		"item_id":       itemID,
+		"output_index":  outputIndex,
+		"content_index": contentIndex,
+		"part":          part,
+	}
+}
+
 func BuildResponsesTextDeltaPayload(responseID, delta string) map[string]any {
 	return map[string]any{
 		"type":        "response.output_text.delta",
@@ -29,48 +77,6 @@ func BuildResponsesReasoningDeltaPayload(responseID, delta string) map[string]an
 	}
 }
 
-func BuildResponsesReasoningTextDeltaPayload(responseID, itemID string, outputIndex, contentIndex int, delta string) map[string]any {
-	return map[string]any{
-		"type":          "response.reasoning_text.delta",
-		"id":            responseID,
-		"response_id":   responseID,
-		"item_id":       itemID,
-		"output_index":  outputIndex,
-		"content_index": contentIndex,
-		"delta":         delta,
-	}
-}
-
-func BuildResponsesReasoningTextDonePayload(responseID, itemID string, outputIndex, contentIndex int, text string) map[string]any {
-	return map[string]any{
-		"type":          "response.reasoning_text.done",
-		"id":            responseID,
-		"response_id":   responseID,
-		"item_id":       itemID,
-		"output_index":  outputIndex,
-		"content_index": contentIndex,
-		"text":          text,
-	}
-}
-
-func BuildResponsesToolCallDeltaPayload(responseID string, toolCalls []map[string]any) map[string]any {
-	return map[string]any{
-		"type":        "response.output_tool_call.delta",
-		"id":          responseID,
-		"response_id": responseID,
-		"tool_calls":  toolCalls,
-	}
-}
-
-func BuildResponsesToolCallDonePayload(responseID string, toolCalls []map[string]any) map[string]any {
-	return map[string]any{
-		"type":        "response.output_tool_call.done",
-		"id":          responseID,
-		"response_id": responseID,
-		"tool_calls":  toolCalls,
-	}
-}
-
 func BuildResponsesFunctionCallArgumentsDeltaPayload(responseID, itemID string, outputIndex int, callID, delta string) map[string]any {
 	return map[string]any{
 		"type":         "response.function_call_arguments.delta",
@@ -96,6 +102,27 @@ func BuildResponsesFunctionCallArgumentsDonePayload(responseID, itemID string, o
 	}
 }
 
+func BuildResponsesFailedPayload(responseID, model, message, code string) map[string]any {
+	code = strings.TrimSpace(code)
+	if code == "" {
+		code = "api_error"
+	}
+	return map[string]any{
+		"type":        "response.failed",
+		"id":          responseID,
+		"response_id": responseID,
+		"object":      "response",
+		"model":       model,
+		"status":      "failed",
+		"error": map[string]any{
+			"message": message,
+			"type":    "invalid_request_error",
+			"code":    code,
+			"param":   nil,
+		},
+	}
+}
+
 func BuildResponsesCompletedPayload(response map[string]any) map[string]any {
 	responseID, _ := response["id"].(string)
 	return map[string]any{

internal/format/openai/render_test.go

@@ -21,8 +21,8 @@ func TestBuildResponseObjectToolCallsFollowChatShape(t *testing.T) {
 	}
 
 	output, _ := obj["output"].([]any)
-	if len(output) != 2 {
-		t.Fatalf("expected function_call + tool_calls wrapper, got %#v", obj["output"])
+	if len(output) != 1 {
+		t.Fatalf("expected function_call output only, got %#v", obj["output"])
 	}
 
 	first, _ := output[0].(map[string]any)
@@ -32,35 +32,10 @@ func TestBuildResponseObjectToolCallsFollowChatShape(t *testing.T) {
 	if first["call_id"] == "" {
 		t.Fatalf("expected function_call item to have call_id, got %#v", first)
 	}
-	second, _ := output[1].(map[string]any)
-	if second["type"] != "tool_calls" {
-		t.Fatalf("expected second output item type tool_calls, got %#v", second["type"])
+	if first["name"] != "search" {
+		t.Fatalf("unexpected function name: %#v", first["name"])
 	}
-	var toolCalls []map[string]any
-	switch v := second["tool_calls"].(type) {
-	case []map[string]any:
-		toolCalls = v
-	case []any:
-		toolCalls = make([]map[string]any, 0, len(v))
-		for _, item := range v {
-			m, _ := item.(map[string]any)
-			if m != nil {
-				toolCalls = append(toolCalls, m)
-			}
-		}
-	}
-	if len(toolCalls) != 1 {
-		t.Fatalf("expected one tool call, got %#v", second["tool_calls"])
-	}
-	tc := toolCalls[0]
-	if tc["type"] != "function" || tc["id"] == "" {
-		t.Fatalf("unexpected tool call shape: %#v", tc)
-	}
-	fn, _ := tc["function"].(map[string]any)
-	if fn["name"] != "search" {
-		t.Fatalf("unexpected function name: %#v", fn["name"])
-	}
-	argsRaw, _ := fn["arguments"].(string)
+	argsRaw, _ := first["arguments"].(string)
 	var args map[string]any
 	if err := json.Unmarshal([]byte(argsRaw), &args); err != nil {
 		t.Fatalf("arguments should be valid json string, got=%q err=%v", argsRaw, err)
@@ -86,8 +61,8 @@ func TestBuildResponseObjectTreatsMixedProseToolPayloadAsToolCall(t *testing.T)
 	}
 
 	output, _ := obj["output"].([]any)
-	if len(output) != 2 {
-		t.Fatalf("expected function_call + tool_calls wrapper, got %#v", obj["output"])
+	if len(output) != 1 {
+		t.Fatalf("expected function_call output only, got %#v", obj["output"])
 	}
 	first, _ := output[0].(map[string]any)
 	if first["type"] != "function_call" {
@@ -163,8 +138,8 @@ func TestBuildResponseObjectDetectsToolCallFromThinkingChannel(t *testing.T) {
 	)
 
 	output, _ := obj["output"].([]any)
-	if len(output) != 3 {
-		t.Fatalf("expected reasoning + function_call + tool_calls outputs, got %#v", obj["output"])
+	if len(output) != 2 {
+		t.Fatalf("expected reasoning + function_call outputs, got %#v", obj["output"])
 	}
 	first, _ := output[0].(map[string]any)
 	if first["type"] != "reasoning" {
@@ -174,8 +149,4 @@ func TestBuildResponseObjectDetectsToolCallFromThinkingChannel(t *testing.T) {
 	if second["type"] != "function_call" {
 		t.Fatalf("expected second output function_call, got %#v", second["type"])
 	}
-	third, _ := output[2].(map[string]any)
-	if third["type"] != "tool_calls" {
-		t.Fatalf("expected third output tool_calls, got %#v", third["type"])
-	}
 }