fix: 修正 conversion 代理路径和错误边界

backend/internal/provider/client.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"net"
 	"net/http"
+	"strings"
 	"syscall"
 	"time"
 
@@ -43,6 +44,14 @@ type StreamEvent struct {
 	Done  bool
 }
 
+// StreamResponse 表示上游流式 HTTP 响应。
+type StreamResponse struct {
+	StatusCode int
+	Headers    map[string]string
+	Body       []byte
+	Events     <-chan StreamEvent
+}
+
 // Client 协议无关的供应商客户端
 type Client struct {
 	httpClient *http.Client
@@ -55,7 +64,7 @@ type Client struct {
 //go:generate go run go.uber.org/mock/mockgen -source=client.go -destination=../../tests/mocks/mock_provider_client.go -package=mocks
 type ProviderClient interface {
 	Send(ctx context.Context, spec conversion.HTTPRequestSpec) (*conversion.HTTPResponseSpec, error)
-	SendStream(ctx context.Context, spec conversion.HTTPRequestSpec) (<-chan StreamEvent, error)
+	SendStream(ctx context.Context, spec conversion.HTTPRequestSpec) (*StreamResponse, error)
 }
 
 // NewClient 创建供应商客户端
@@ -116,7 +125,7 @@ func (c *Client) Send(ctx context.Context, spec conversion.HTTPRequestSpec) (*co
 }
 
 // SendStream 发送流式请求
-func (c *Client) SendStream(ctx context.Context, spec conversion.HTTPRequestSpec) (<-chan StreamEvent, error) {
+func (c *Client) SendStream(ctx context.Context, spec conversion.HTTPRequestSpec) (*StreamResponse, error) {
 	var bodyReader io.Reader
 	if len(spec.Body) > 0 {
 		bodyReader = bytes.NewReader(spec.Body)
@@ -139,23 +148,29 @@ func (c *Client) SendStream(ctx context.Context, spec conversion.HTTPRequestSpec
 		return nil, pkgErrors.ErrRequestSend.WithCause(err)
 	}
 
-	if resp.StatusCode != http.StatusOK {
+	respHeaders := extractResponseHeaders(resp.Header)
+	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
 		defer resp.Body.Close()
 		cancel()
 		errBody, readErr := io.ReadAll(resp.Body)
 		if readErr != nil {
-			return nil, fmt.Errorf("供应商返回错误: HTTP %d，读取错误响应失败: %w", resp.StatusCode, readErr)
+			return nil, pkgErrors.ErrResponseRead.WithCause(readErr)
 		}
-		if len(errBody) > 0 {
-			return nil, fmt.Errorf("供应商返回错误: HTTP %d: %s", resp.StatusCode, string(errBody))
-		}
-		return nil, fmt.Errorf("供应商返回错误: HTTP %d", resp.StatusCode)
+		return &StreamResponse{
+			StatusCode: resp.StatusCode,
+			Headers:    respHeaders,
+			Body:       errBody,
+		}, nil
 	}
 
 	eventChan := make(chan StreamEvent, c.streamCfg.ChannelBufferSize)
 	go c.readStream(streamCtx, cancel, resp.Body, eventChan)
 
-	return eventChan, nil
+	return &StreamResponse{
+		StatusCode: resp.StatusCode,
+		Headers:    respHeaders,
+		Events:     eventChan,
+	}, nil
 }
 
 // readStream 读取 SSE 流
@@ -208,15 +223,17 @@ func (c *Client) readStream(ctx context.Context, cancel context.CancelFunc, body
 		}
 
 		for {
-			idx := bytes.Index(dataBuf, []byte("\n\n"))
+			idx, sepLen := findSSEFrameSeparator(dataBuf)
 			if idx == -1 {
 				break
 			}
 
-			rawEvent := dataBuf[:idx]
-			dataBuf = dataBuf[idx+2:]
+			frameEnd := idx + sepLen
+			rawEvent := append([]byte(nil), dataBuf[:frameEnd]...)
+			dataBuf = dataBuf[frameEnd:]
 
-			if bytes.Contains(rawEvent, []byte("data: [DONE]")) {
+			if isSSEDoneFrame(rawEvent) {
+				eventChan <- StreamEvent{Data: rawEvent}
 				eventChan <- StreamEvent{Done: true}
 				return
 			}
@@ -225,11 +242,66 @@ func (c *Client) readStream(ctx context.Context, cancel context.CancelFunc, body
 		}
 
 		if err == io.EOF {
+			if len(dataBuf) > 0 {
+				eventChan <- StreamEvent{Data: dataBuf}
+			}
 			return
 		}
 	}
 }
 
+func isSSEDoneFrame(frame []byte) bool {
+	payload, ok := sseFrameDataPayload(frame)
+	return ok && strings.TrimSpace(payload) == "[DONE]"
+}
+
+func sseFrameDataPayload(frame []byte) (string, bool) {
+	text := strings.TrimRight(string(frame), "\r\n")
+	lines := strings.Split(text, "\n")
+	var dataLines []string
+	for _, line := range lines {
+		line = strings.TrimRight(line, "\r")
+		if strings.HasPrefix(line, "data:") {
+			value := strings.TrimPrefix(line, "data:")
+			if strings.HasPrefix(value, " ") {
+				value = value[1:]
+			}
+			dataLines = append(dataLines, value)
+		}
+	}
+	if len(dataLines) == 0 {
+		return "", false
+	}
+	return strings.Join(dataLines, "\n"), true
+}
+
+func extractResponseHeaders(header http.Header) map[string]string {
+	respHeaders := make(map[string]string)
+	for k, vs := range header {
+		if len(vs) > 0 {
+			respHeaders[k] = vs[0]
+		}
+	}
+	return respHeaders
+}
+
+func findSSEFrameSeparator(data []byte) (int, int) {
+	lf := bytes.Index(data, []byte("\n\n"))
+	crlf := bytes.Index(data, []byte("\r\n\r\n"))
+	switch {
+	case lf < 0 && crlf < 0:
+		return -1, 0
+	case lf < 0:
+		return crlf, 4
+	case crlf < 0:
+		return lf, 2
+	case crlf <= lf:
+		return crlf, 4
+	default:
+		return lf, 2
+	}
+}
+
 // isNetworkError 判断是否为网络相关错误
 func isNetworkError(err error) bool {
 	if err == nil {