feat(llm): support OpenAI Responses API via per-provider api_type

2026-08-13 11:46:23 +08:00
parent c8d8329dbb
commit 425f6ee5ee
9 changed files with 979 additions and 4 deletions
@@ -0,0 +1,460 @@
+package llm
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"sort"
+	"strings"
+)
+
+const responsesEndpoint = "/v1/responses"
+
+// OpenAIResponsesClient implements llm.Provider against the OpenAI Responses
+// API (/v1/responses). It maps the agent's chat-style conversation history to
+// Responses input items (messages, function_call, function_call_output) and
+// converts Responses streaming events back into the shared StreamEvent shape.
+type OpenAIResponsesClient struct {
+	baseURL    string
+	apiKey     string
+	httpClient *http.Client
+}
+
+func NewOpenAIResponsesClient(baseURL, apiKey string, httpClient *http.Client) *OpenAIResponsesClient {
+	if httpClient == nil {
+		httpClient = http.DefaultClient
+	}
+	return &OpenAIResponsesClient{
+		baseURL:    strings.TrimRight(baseURL, "/"),
+		apiKey:     apiKey,
+		httpClient: httpClient,
+	}
+}
+
+func (c *OpenAIResponsesClient) ChatStream(ctx context.Context, req ChatRequest, emit func(StreamEvent) error) error {
+	body, err := json.Marshal(buildResponsesRequest(req))
+	if err != nil {
+		return fmt.Errorf("marshal responses request: %w", err)
+	}
+	state := &responsesStreamState{}
+	return postResponsesSSE(ctx, c.baseURL, c.apiKey, c.httpClient, body, func(payload string) error {
+		return state.handle(payload, emit)
+	})
+}
+
+func postResponsesSSE(ctx context.Context, baseURL, apiKey string, httpClient *http.Client, body []byte, handle func(payload string) error) error {
+	var lastErr error
+	for attempt := 1; attempt <= maxChatAttempts; attempt++ {
+		httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, baseURL+responsesEndpoint, bytes.NewReader(body))
+		if err != nil {
+			return fmt.Errorf("create responses request: %w", err)
+		}
+		httpReq.Header.Set("Content-Type", "application/json")
+		httpReq.Header.Set("Accept", "text/event-stream")
+		if apiKey != "" {
+			httpReq.Header.Set("Authorization", "Bearer "+apiKey)
+		}
+
+		resp, err := httpClient.Do(httpReq)
+		if err != nil {
+			lastErr = fmt.Errorf("send responses request: %w", err)
+			if !shouldRetryRequest(ctx, attempt, 0) {
+				return lastErr
+			}
+			if waitErr := waitBeforeRetry(ctx); waitErr != nil {
+				return waitErr
+			}
+			continue
+		}
+
+		if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+			limit := io.LimitReader(resp.Body, 4096)
+			data, _ := io.ReadAll(limit)
+			_ = resp.Body.Close()
+			lastErr = fmt.Errorf("responses request failed: status=%d body=%s", resp.StatusCode, strings.TrimSpace(string(data)))
+			if !shouldRetryRequest(ctx, attempt, resp.StatusCode) {
+				return lastErr
+			}
+			if waitErr := waitBeforeRetry(ctx); waitErr != nil {
+				return waitErr
+			}
+			continue
+		}
+
+		defer resp.Body.Close()
+		return readResponsesSSE(resp.Body, handle)
+	}
+	return lastErr
+}
+
+func readResponsesSSE(r io.Reader, handle func(payload string) error) error {
+	reader := bufio.NewReader(r)
+	for {
+		line, err := reader.ReadString('\n')
+		if err != nil && !errors.Is(err, io.EOF) {
+			return fmt.Errorf("read responses stream: %w", err)
+		}
+
+		line = strings.TrimSpace(line)
+		if strings.HasPrefix(line, "data:") {
+			payload := strings.TrimSpace(strings.TrimPrefix(line, "data:"))
+			if payload == "[DONE]" {
+				return nil
+			}
+			if handleErr := handle(payload); handleErr != nil {
+				return handleErr
+			}
+		}
+
+		if errors.Is(err, io.EOF) {
+			return nil
+		}
+	}
+}
+
+// buildResponsesRequest converts a ChatRequest into the /v1/responses body.
+func buildResponsesRequest(req ChatRequest) map[string]any {
+	payload := map[string]any{
+		"model":  req.Model,
+		"input":  buildResponsesInput(req.Messages),
+		"stream": true,
+	}
+	if len(req.Tools) > 0 {
+		payload["tools"] = buildResponsesTools(req.Tools)
+	}
+	if req.ToolChoice != "" {
+		payload["tool_choice"] = req.ToolChoice
+	}
+	for key, value := range req.Extra {
+		if _, exists := payload[key]; exists {
+			continue
+		}
+		if key == "reasoning" {
+			if level, ok := value.(string); ok {
+				payload[key] = map[string]any{"effort": mapReasoningEffort(level)}
+				continue
+			}
+		}
+		payload[key] = value
+	}
+	return payload
+}
+
+// buildResponsesInput maps chat-style messages to Responses input items.
+// Assistant tool calls become function_call items and tool results become
+// function_call_output items, preserving their position in the conversation.
+func buildResponsesInput(messages []Message) []any {
+	items := make([]any, 0, len(messages)+4)
+	for _, msg := range messages {
+		switch msg.Role {
+		case RoleSystem:
+			items = append(items, responsesMessageInput{Role: "system", Content: msg.Content})
+		case RoleUser:
+			items = append(items, responsesMessageInput{Role: "user", Content: msg.Content})
+		case RoleAssistant:
+			if msg.Content != "" {
+				items = append(items, responsesMessageInput{Role: "assistant", Content: msg.Content})
+			}
+			for _, call := range msg.ToolCalls {
+				items = append(items, responsesFunctionCallInput{
+					Type:      "function_call",
+					CallID:    call.ID,
+					Name:      call.Function.Name,
+					Arguments: call.Function.Arguments,
+				})
+			}
+		case RoleTool:
+			items = append(items, responsesFunctionCallOutput{
+				Type:   "function_call_output",
+				CallID: msg.ToolCallID,
+				Output: msg.Content,
+			})
+		}
+	}
+	return items
+}
+
+func buildResponsesTools(tools []Tool) []responsesTool {
+	out := make([]responsesTool, 0, len(tools))
+	for _, tool := range tools {
+		out = append(out, responsesTool{
+			Type:        "function",
+			Name:        tool.Function.Name,
+			Description: tool.Function.Description,
+			Parameters:  tool.Function.Parameters,
+		})
+	}
+	return out
+}
+
+func mapReasoningEffort(level string) string {
+	level = strings.ToLower(strings.TrimSpace(level))
+	if level == "middle" {
+		return "medium"
+	}
+	return level
+}
+
+type responsesMessageInput struct {
+	Role    string `json:"role"`
+	Content string `json:"content"`
+}
+
+type responsesFunctionCallInput struct {
+	Type      string `json:"type"`
+	CallID    string `json:"call_id"`
+	Name      string `json:"name"`
+	Arguments string `json:"arguments"`
+}
+
+type responsesFunctionCallOutput struct {
+	Type   string `json:"type"`
+	CallID string `json:"call_id"`
+	Output string `json:"output"`
+}
+
+type responsesTool struct {
+	Type        string          `json:"type"`
+	Name        string          `json:"name"`
+	Description string          `json:"description,omitempty"`
+	Parameters  json.RawMessage `json:"parameters,omitempty"`
+}
+
+// responsesStreamState tracks in-flight output items while parsing SSE events.
+type responsesStreamState struct {
+	calls map[int]*responsesCallBuilder
+	done  bool
+}
+
+type responsesCallBuilder struct {
+	index     int
+	id        string
+	callType  string
+	name      string
+	arguments strings.Builder
+	finalized bool
+}
+
+func (s *responsesStreamState) handle(payload string, emit func(StreamEvent) error) error {
+	if s.done {
+		return nil
+	}
+	var event responsesStreamEvent
+	if err := json.Unmarshal([]byte(payload), &event); err != nil {
+		return fmt.Errorf("parse responses stream payload: %w", err)
+	}
+
+	switch event.Type {
+	case "error":
+		s.done = true
+		return event.err()
+	case "response.failed":
+		s.done = true
+		if event.Response != nil && event.Response.Error != nil {
+			return fmt.Errorf("provider error: %s: %s", event.Response.Error.Code, event.Response.Error.Message)
+		}
+		return fmt.Errorf("provider error: response failed")
+	case "response.incomplete":
+		s.done = true
+		return s.finish(emit, "length", nil)
+	case "response.completed":
+		s.done = true
+		var usage *Usage
+		if event.Response != nil && event.Response.Usage != nil {
+			usage = &Usage{
+				PromptTokens:     event.Response.Usage.InputTokens,
+				CompletionTokens: event.Response.Usage.OutputTokens,
+				TotalTokens:      event.Response.Usage.TotalTokens,
+			}
+		}
+		return s.finish(emit, "stop", usage)
+	case "response.output_text.delta":
+		if event.Delta != "" {
+			return emit(StreamEvent{Content: event.Delta})
+		}
+	case "response.output_item.added":
+		if event.Item != nil && event.Item.Type == "function_call" {
+			s.builder(event.OutputIndex).applyAdded(*event.Item)
+		}
+	case "response.function_call_arguments.delta":
+		if event.Delta != "" {
+			s.builder(event.OutputIndex).arguments.WriteString(event.Delta)
+		}
+	case "response.function_call_arguments.done":
+		builder := s.builder(event.OutputIndex)
+		if event.Name != "" {
+			builder.name = event.Name
+		}
+		if event.Arguments != "" {
+			builder.arguments.Reset()
+			builder.arguments.WriteString(event.Arguments)
+		}
+	case "response.output_item.done":
+		if event.Item != nil && event.Item.Type == "function_call" {
+			builder := s.builder(event.OutputIndex)
+			builder.applyDone(*event.Item)
+			return s.emitCall(builder, emit)
+		}
+	}
+	return nil
+}
+
+// finish flushes any not-yet-finalized function calls and reports the
+// terminal finish reason.
+func (s *responsesStreamState) finish(emit func(StreamEvent) error, finishReason string, usage *Usage) error {
+	if len(s.calls) == 0 {
+		return emit(StreamEvent{FinishReason: finishReason, Usage: usage})
+	}
+	indexes := make([]int, 0, len(s.calls))
+	for index := range s.calls {
+		indexes = append(indexes, index)
+	}
+	sort.Ints(indexes)
+	var deltas []ToolCallDelta
+	for _, index := range indexes {
+		builder := s.calls[index]
+		if builder.finalized {
+			continue
+		}
+		builder.finalized = true
+		deltas = append(deltas, builder.delta())
+	}
+	if len(deltas) > 0 {
+		if err := emit(StreamEvent{ToolCalls: deltas}); err != nil {
+			return err
+		}
+	}
+	return emit(StreamEvent{FinishReason: finishReason, Usage: usage})
+}
+
+func (s *responsesStreamState) emitCall(builder *responsesCallBuilder, emit func(StreamEvent) error) error {
+	if builder.finalized {
+		return nil
+	}
+	builder.finalized = true
+	return emit(StreamEvent{ToolCalls: []ToolCallDelta{builder.delta()}})
+}
+
+func (s *responsesStreamState) builder(index int) *responsesCallBuilder {
+	if s.calls == nil {
+		s.calls = make(map[int]*responsesCallBuilder)
+	}
+	builder := s.calls[index]
+	if builder == nil {
+		builder = &responsesCallBuilder{index: index}
+		s.calls[index] = builder
+	}
+	return builder
+}
+
+func (b *responsesCallBuilder) applyAdded(item responsesStreamItem) {
+	if b.id == "" {
+		b.id = item.CallID
+		if b.id == "" {
+			b.id = item.ID
+		}
+	}
+	if b.name == "" {
+		b.name = item.Name
+	}
+	if item.Arguments != "" {
+		b.arguments.Reset()
+		b.arguments.WriteString(item.Arguments)
+	}
+}
+
+func (b *responsesCallBuilder) applyDone(item responsesStreamItem) {
+	if item.CallID != "" {
+		b.id = item.CallID
+	} else if item.ID != "" {
+		b.id = item.ID
+	}
+	if item.Name != "" {
+		b.name = item.Name
+	}
+	if item.Arguments != "" {
+		b.arguments.Reset()
+		b.arguments.WriteString(item.Arguments)
+	}
+}
+
+func (b *responsesCallBuilder) delta() ToolCallDelta {
+	id := b.id
+	if id == "" {
+		id = fmt.Sprintf("call_%d", b.index)
+	}
+	callType := b.callType
+	if callType == "" {
+		callType = "function"
+	}
+	return ToolCallDelta{
+		Index:     b.index,
+		ID:        id,
+		Type:      callType,
+		Name:      b.name,
+		Arguments: b.arguments.String(),
+	}
+}
+
+type responsesStreamEvent struct {
+	Type        string                   `json:"type"`
+	OutputIndex int                      `json:"output_index"`
+	Delta       string                   `json:"delta"`
+	Arguments   string                   `json:"arguments"`
+	Name        string                   `json:"name"`
+	Code        string                   `json:"code"`
+	Message     string                   `json:"message"`
+	Param       string                   `json:"param"`
+	Item        *responsesStreamItem     `json:"item"`
+	Response    *responsesStreamResponse `json:"response"`
+	Error       *responsesStreamError    `json:"error"`
+}
+
+type responsesStreamItem struct {
+	Type      string `json:"type"`
+	ID        string `json:"id"`
+	CallID    string `json:"call_id"`
+	Name      string `json:"name"`
+	Arguments string `json:"arguments"`
+}
+
+type responsesStreamResponse struct {
+	Status string                `json:"status"`
+	Error  *responsesStreamError `json:"error"`
+	Usage  *responsesStreamUsage `json:"usage"`
+}
+
+type responsesStreamUsage struct {
+	InputTokens  int `json:"input_tokens"`
+	OutputTokens int `json:"output_tokens"`
+	TotalTokens  int `json:"total_tokens"`
+}
+
+type responsesStreamError struct {
+	Type    string `json:"type"`
+	Code    string `json:"code"`
+	Message string `json:"message"`
+	Param   string `json:"param"`
+}
+
+func (e responsesStreamEvent) err() error {
+	code, message, param := e.Code, e.Message, e.Param
+	if code == "" && message == "" && e.Error != nil {
+		code, message, param = e.Error.Code, e.Error.Message, e.Error.Param
+	}
+	if message == "" {
+		if param != "" {
+			return fmt.Errorf("provider error: %s", param)
+		}
+		return fmt.Errorf("provider error")
+	}
+	if code != "" {
+		return fmt.Errorf("provider error: %s: %s", code, message)
+	}
+	return fmt.Errorf("provider error: %s", message)
+}