Enable streaming UI updates for chat responses
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@@ -87,15 +87,174 @@ func (c *Client) CreateChatCompletion(ctx context.Context, req ChatCompletionReq
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defer resp.Body.Close()
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if resp.StatusCode >= 200 && resp.StatusCode < 300 {
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if req.Stream {
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return decodeStream(resp.Body)
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}
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return decodeSuccess(resp.Body)
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}
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return nil, decodeError(resp.Body, resp.StatusCode)
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}
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// StreamChatCompletion issues a streaming chat completion request and invokes handler for each chunk.
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func (c *Client) StreamChatCompletion(ctx context.Context, req ChatCompletionRequest, handler ChatCompletionStreamHandler) (*ChatCompletionResponse, error) {
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if c == nil {
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return nil, errors.New("client is nil")
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}
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req.Stream = true
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payload, err := json.Marshal(req)
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if err != nil {
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return nil, fmt.Errorf("encode request: %w", err)
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}
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httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/chat/completions", bytes.NewReader(payload))
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if err != nil {
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return nil, fmt.Errorf("create request: %w", err)
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}
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httpReq.Header.Set("Content-Type", "application/json")
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httpReq.Header.Set("Authorization", "Bearer "+c.apiKey)
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httpReq.Header.Set("Accept", "text/event-stream")
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resp, err := c.httpClient.Do(httpReq)
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if err != nil {
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return nil, fmt.Errorf("execute request: %w", err)
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}
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defer resp.Body.Close()
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if resp.StatusCode < 200 || resp.StatusCode >= 300 {
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return nil, decodeError(resp.Body, resp.StatusCode)
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}
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scanner := bufio.NewScanner(resp.Body)
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scanner.Buffer(make([]byte, 0, 64*1024), 1<<20)
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type streamChunk struct {
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ID string `json:"id"`
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Object string `json:"object"`
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Choices []struct {
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Index int `json:"index"`
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Message ChatMessage `json:"message"`
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Delta ChatMessage `json:"delta"`
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FinishReason string `json:"finish_reason"`
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} `json:"choices"`
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Usage Usage `json:"usage"`
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}
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var aggregated ChatCompletionResponse
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var builder strings.Builder
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role := "assistant"
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finish := ""
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var usage Usage
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usageReceived := false
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for scanner.Scan() {
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line := scanner.Text()
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line = strings.TrimSpace(line)
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if line == "" {
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continue
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}
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if !strings.HasPrefix(line, "data:") {
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continue
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}
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payloadLine := strings.TrimSpace(strings.TrimPrefix(line, "data:"))
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if payloadLine == "" {
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continue
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}
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if payloadLine == "[DONE]" {
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if handler != nil {
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if err := handler(ChatCompletionStreamEvent{Done: true}); err != nil {
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return nil, err
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}
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}
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break
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}
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var chunk streamChunk
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if err := json.Unmarshal([]byte(payloadLine), &chunk); err != nil {
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return nil, fmt.Errorf("decode stream response: %w", err)
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}
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if aggregated.ID == "" {
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aggregated.ID = chunk.ID
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}
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if aggregated.Object == "" {
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aggregated.Object = chunk.Object
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}
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if chunk.Usage != (Usage{}) {
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usage = chunk.Usage
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usageReceived = true
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}
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var chunkText string
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finishReason := ""
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if len(chunk.Choices) > 0 {
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choice := chunk.Choices[0]
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if choice.Message.Role != "" {
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role = choice.Message.Role
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}
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if choice.Delta.Role != "" {
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role = choice.Delta.Role
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}
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if choice.Delta.Content != "" {
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chunkText = choice.Delta.Content
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} else if choice.Message.Content != "" && builder.Len() == 0 {
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chunkText = choice.Message.Content
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}
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if choice.Message.Content != "" && builder.Len() == 0 && chunkText == "" {
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chunkText = choice.Message.Content
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}
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if choice.FinishReason != "" {
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finishReason = choice.FinishReason
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finish = choice.FinishReason
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}
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}
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if chunkText != "" {
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builder.WriteString(chunkText)
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}
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if handler != nil {
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event := ChatCompletionStreamEvent{
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ID: chunk.ID,
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Role: role,
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Content: chunkText,
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FinishReason: finishReason,
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}
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if usageReceived {
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u := usage
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event.Usage = &u
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}
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if err := handler(event); err != nil {
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return nil, err
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}
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}
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}
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if err := scanner.Err(); err != nil {
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return nil, fmt.Errorf("read stream: %w", err)
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}
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content := strings.TrimSpace(builder.String())
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if content == "" {
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return nil, errors.New("stream response contained no content")
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}
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aggregated.Choices = []ChatCompletionChoice{{
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Index: 0,
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Message: ChatMessage{
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Role: role,
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Content: content,
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},
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FinishReason: finish,
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}}
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if usageReceived {
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aggregated.Usage = usage
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}
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return &aggregated, nil
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}
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func decodeSuccess(r io.Reader) (*ChatCompletionResponse, error) {
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data, err := io.ReadAll(r)
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if err != nil {
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@@ -118,100 +277,6 @@ func decodeSuccess(r io.Reader) (*ChatCompletionResponse, error) {
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return &response, nil
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}
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func decodeStream(r io.Reader) (*ChatCompletionResponse, error) {
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scanner := bufio.NewScanner(r)
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var payloads []json.RawMessage
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for scanner.Scan() {
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line := scanner.Text()
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if strings.HasPrefix(line, "data: ") {
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payload := strings.TrimPrefix(line, "data: ")
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if payload == "[DONE]" {
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break
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}
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payloads = append(payloads, json.RawMessage(payload))
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}
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}
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if err := scanner.Err(); err != nil {
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return nil, fmt.Errorf("read stream: %w", err)
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}
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if len(payloads) == 0 {
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return nil, errors.New("empty stream response")
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}
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type streamChunk struct {
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ID string `json:"id"`
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Object string `json:"object"`
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Choices []struct {
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Index int `json:"index"`
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Message ChatMessage `json:"message"`
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Delta ChatMessage `json:"delta"`
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FinishReason string `json:"finish_reason"`
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} `json:"choices"`
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Usage Usage `json:"usage"`
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}
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var aggregated ChatCompletionResponse
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var builder strings.Builder
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role := "assistant"
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finish := ""
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for _, payload := range payloads {
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var chunk streamChunk
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if err := json.Unmarshal(payload, &chunk); err != nil {
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return nil, fmt.Errorf("decode stream response: %w", err)
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}
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if aggregated.ID == "" {
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aggregated.ID = chunk.ID
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}
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if aggregated.Object == "" {
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aggregated.Object = chunk.Object
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}
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aggregated.Usage.PromptTokens += chunk.Usage.PromptTokens
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aggregated.Usage.CompletionTokens += chunk.Usage.CompletionTokens
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aggregated.Usage.TotalTokens += chunk.Usage.TotalTokens
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if len(chunk.Choices) == 0 {
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continue
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}
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choice := chunk.Choices[0]
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if choice.Message.Role != "" {
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role = choice.Message.Role
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}
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if choice.Delta.Role != "" {
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role = choice.Delta.Role
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}
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if choice.Message.Content != "" {
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builder.WriteString(choice.Message.Content)
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}
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if choice.Delta.Content != "" {
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builder.WriteString(choice.Delta.Content)
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}
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if choice.FinishReason != "" {
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finish = choice.FinishReason
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}
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}
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content := strings.TrimSpace(builder.String())
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if content == "" {
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return nil, errors.New("stream response contained no content")
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}
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aggregated.Choices = []ChatCompletionChoice{{
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Index: 0,
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FinishReason: finish,
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Message: ChatMessage{
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Role: role,
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Content: content,
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},
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}}
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return &aggregated, nil
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}
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func decodeError(r io.Reader, status int) error {
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var apiErr ErrorResponse
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if err := json.NewDecoder(r).Decode(&apiErr); err != nil {
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@@ -37,6 +37,19 @@ type ChatCompletionResponse struct {
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Usage Usage `json:"usage"`
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}
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// ChatCompletionStreamEvent represents a single chunk in a streaming chat completion.
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type ChatCompletionStreamEvent struct {
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ID string `json:"-"`
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Role string `json:"-"`
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Content string `json:"-"`
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FinishReason string `json:"-"`
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Usage *Usage `json:"-"`
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Done bool `json:"-"`
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}
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// ChatCompletionStreamHandler consumes streaming completion events.
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type ChatCompletionStreamHandler func(ChatCompletionStreamEvent) error
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// APIError captures structured error responses returned by the API.
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type APIError struct {
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Message string `json:"message"`
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