refactor: Extract OpenAI streaming response payload construction into dedicated utility functions.

internal/util/render_stream.go

@@ -0,0 +1,93 @@
+package util
+
+func BuildOpenAIChatStreamDeltaChoice(index int, delta map[string]any) map[string]any {
+	return map[string]any{
+		"delta": delta,
+		"index": index,
+	}
+}
+
+func BuildOpenAIChatStreamFinishChoice(index int, finishReason string) map[string]any {
+	return map[string]any{
+		"delta":         map[string]any{},
+		"index":         index,
+		"finish_reason": finishReason,
+	}
+}
+
+func BuildOpenAIChatStreamChunk(completionID string, created int64, model string, choices []map[string]any, usage map[string]any) map[string]any {
+	out := map[string]any{
+		"id":      completionID,
+		"object":  "chat.completion.chunk",
+		"created": created,
+		"model":   model,
+		"choices": choices,
+	}
+	if len(usage) > 0 {
+		out["usage"] = usage
+	}
+	return out
+}
+
+func BuildOpenAIChatUsage(finalPrompt, finalThinking, finalText string) map[string]any {
+	promptTokens := EstimateTokens(finalPrompt)
+	reasoningTokens := EstimateTokens(finalThinking)
+	completionTokens := EstimateTokens(finalText)
+	return map[string]any{
+		"prompt_tokens":     promptTokens,
+		"completion_tokens": reasoningTokens + completionTokens,
+		"total_tokens":      promptTokens + reasoningTokens + completionTokens,
+		"completion_tokens_details": map[string]any{
+			"reasoning_tokens": reasoningTokens,
+		},
+	}
+}
+
+func BuildOpenAIResponsesCreatedPayload(responseID, model string) map[string]any {
+	return map[string]any{
+		"type":   "response.created",
+		"id":     responseID,
+		"object": "response",
+		"model":  model,
+		"status": "in_progress",
+	}
+}
+
+func BuildOpenAIResponsesTextDeltaPayload(responseID, delta string) map[string]any {
+	return map[string]any{
+		"type":  "response.output_text.delta",
+		"id":    responseID,
+		"delta": delta,
+	}
+}
+
+func BuildOpenAIResponsesReasoningDeltaPayload(responseID, delta string) map[string]any {
+	return map[string]any{
+		"type":  "response.reasoning.delta",
+		"id":    responseID,
+		"delta": delta,
+	}
+}
+
+func BuildOpenAIResponsesToolCallDeltaPayload(responseID string, toolCalls []map[string]any) map[string]any {
+	return map[string]any{
+		"type":       "response.output_tool_call.delta",
+		"id":         responseID,
+		"tool_calls": toolCalls,
+	}
+}
+
+func BuildOpenAIResponsesToolCallDonePayload(responseID string, toolCalls []map[string]any) map[string]any {
+	return map[string]any{
+		"type":       "response.output_tool_call.done",
+		"id":         responseID,
+		"tool_calls": toolCalls,
+	}
+}
+
+func BuildOpenAIResponsesCompletedPayload(response map[string]any) map[string]any {
+	return map[string]any{
+		"type":     "response.completed",
+		"response": response,
+	}
+}

internal/util/render_stream_test.go

@@ -0,0 +1,48 @@
+package util
+
+import "testing"
+
+func TestBuildOpenAIChatStreamChunk(t *testing.T) {
+	chunk := BuildOpenAIChatStreamChunk(
+		"cid",
+		123,
+		"deepseek-chat",
+		[]map[string]any{BuildOpenAIChatStreamDeltaChoice(0, map[string]any{"role": "assistant"})},
+		nil,
+	)
+	if chunk["object"] != "chat.completion.chunk" {
+		t.Fatalf("unexpected object: %#v", chunk["object"])
+	}
+	choices, _ := chunk["choices"].([]map[string]any)
+	if len(choices) == 0 {
+		rawChoices, _ := chunk["choices"].([]any)
+		if len(rawChoices) == 0 {
+			t.Fatalf("expected choices")
+		}
+	}
+}
+
+func TestBuildOpenAIChatUsage(t *testing.T) {
+	usage := BuildOpenAIChatUsage("prompt", "think", "answer")
+	if _, ok := usage["prompt_tokens"]; !ok {
+		t.Fatalf("expected prompt_tokens")
+	}
+	if _, ok := usage["completion_tokens_details"]; !ok {
+		t.Fatalf("expected completion_tokens_details")
+	}
+}
+
+func TestBuildOpenAIResponsesEventPayloads(t *testing.T) {
+	created := BuildOpenAIResponsesCreatedPayload("resp_1", "gpt-4o")
+	if created["type"] != "response.created" {
+		t.Fatalf("unexpected type: %#v", created["type"])
+	}
+	done := BuildOpenAIResponsesToolCallDonePayload("resp_1", []map[string]any{{"index": 0}})
+	if done["type"] != "response.output_tool_call.done" {
+		t.Fatalf("unexpected type: %#v", done["type"])
+	}
+	completed := BuildOpenAIResponsesCompletedPayload(map[string]any{"id": "resp_1"})
+	if completed["type"] != "response.completed" {
+		t.Fatalf("unexpected type: %#v", completed["type"])
+	}
+}