feat: record stream interruption reasons via StreamStatus

- Add StreamStatus type (relay/common) to track stream end reason
  (done/timeout/client_gone/scanner_error/eof/panic/ping_fail) and
  accumulate soft errors during streaming via sync.Once + sync.Mutex.
- Add StreamResult (relay/helper) as the callback interface: adapters
  call sr.Error() for soft errors, sr.Stop() for fatal, sr.Done() for
  normal completion. No early-return problem — multiple errors per chunk
  are naturally supported.
- Refactor StreamScannerHandler callback from func(string) bool to
  func(string, *StreamResult). All 9 channel adapters updated.
- Write stream_status into log other JSON field (admin-only) with
  status ok/error, end_reason, error_count, and error messages.
- Frontend: display stream status in log detail expansion for admins.

relay/helper/stream_result.go

@@ -0,0 +1,52 @@
+package helper
+
+import (
+	relaycommon "github.com/QuantumNous/new-api/relay/common"
+)
+
+// StreamResult is passed to each dataHandler invocation, providing methods
+// to record soft errors, signal fatal stops, or mark normal completion.
+// StreamScannerHandler checks IsStopped() after each callback invocation.
+type StreamResult struct {
+	status  *relaycommon.StreamStatus
+	stopped bool
+}
+
+func newStreamResult(status *relaycommon.StreamStatus) *StreamResult {
+	return &StreamResult{status: status}
+}
+
+// Error records a soft error. The stream continues processing.
+// Can be called multiple times per chunk.
+func (r *StreamResult) Error(err error) {
+	if err == nil {
+		return
+	}
+	r.status.RecordError(err.Error())
+}
+
+// Stop records a fatal error and marks the stream to stop after this chunk.
+func (r *StreamResult) Stop(err error) {
+	if err != nil {
+		r.status.RecordError(err.Error())
+	}
+	r.status.SetEndReason(relaycommon.StreamEndReasonHandlerStop, err)
+	r.stopped = true
+}
+
+// Done signals that the handler has finished processing normally
+// (e.g., Dify "message_end"). The stream stops after this chunk.
+func (r *StreamResult) Done() {
+	r.status.SetEndReason(relaycommon.StreamEndReasonDone, nil)
+	r.stopped = true
+}
+
+// IsStopped returns whether Stop() or Done() was called during this chunk.
+func (r *StreamResult) IsStopped() bool {
+	return r.stopped
+}
+
+// reset clears the per-chunk stopped flag so the object can be reused.
+func (r *StreamResult) reset() {
+	r.stopped = false
+}

relay/helper/stream_scanner.go

@@ -34,12 +34,15 @@ func getScannerBufferSize() int {
 	return DefaultMaxScannerBufferSize
 }
 
-func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon.RelayInfo, dataHandler func(data string) bool) {
+func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon.RelayInfo, dataHandler func(data string, sr *StreamResult)) {
 
 	if resp == nil || dataHandler == nil {
 		return
 	}
 
+	// 无条件新建 StreamStatus
+	info.StreamStatus = relaycommon.NewStreamStatus()
+
 	// 确保响应体总是被关闭
 	defer func() {
 		if resp.Body != nil {
@@ -121,6 +124,7 @@ func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon
 				wg.Done()
 				if r := recover(); r != nil {
 					logger.LogError(c, fmt.Sprintf("ping goroutine panic: %v", r))
+					info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonPanic, fmt.Errorf("ping panic: %v", r))
 					common.SafeSendBool(stopChan, true)
 				}
 				if common.DebugEnabled {
@@ -148,6 +152,7 @@ func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon
 					case err := <-done:
 						if err != nil {
 							logger.LogError(c, "ping data error: "+err.Error())
+							info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonPingFail, err)
 							return
 						}
 						if common.DebugEnabled {
@@ -155,6 +160,7 @@ func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon
 						}
 					case <-time.After(10 * time.Second):
 						logger.LogError(c, "ping data send timeout")
+						info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonPingFail, fmt.Errorf("ping send timeout"))
 						return
 					case <-ctx.Done():
 						return
@@ -184,14 +190,17 @@ func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon
 			wg.Done()
 			if r := recover(); r != nil {
 				logger.LogError(c, fmt.Sprintf("data handler goroutine panic: %v", r))
+				info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonPanic, fmt.Errorf("handler panic: %v", r))
 			}
 			common.SafeSendBool(stopChan, true)
 		}()
+		sr := newStreamResult(info.StreamStatus)
 		for data := range dataChan {
+			sr.reset()
 			writeMutex.Lock()
-			success := dataHandler(data)
+			dataHandler(data, sr)
 			writeMutex.Unlock()
-			if !success {
+			if sr.IsStopped() {
 				return
 			}
 		}
@@ -205,6 +214,7 @@ func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon
 			wg.Done()
 			if r := recover(); r != nil {
 				logger.LogError(c, fmt.Sprintf("scanner goroutine panic: %v", r))
+				info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonPanic, fmt.Errorf("scanner panic: %v", r))
 			}
 			common.SafeSendBool(stopChan, true)
 			if common.DebugEnabled {
@@ -220,6 +230,7 @@ func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon
 			case <-ctx.Done():
 				return
 			case <-c.Request.Context().Done():
+				info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonClientGone, c.Request.Context().Err())
 				return
 			default:
 			}
@@ -253,7 +264,7 @@ func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon
 					return
 				}
 			} else {
-				// done, 处理完成标志，直接退出停止读取剩余数据防止出错
+				info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonDone, nil)
 				if common.DebugEnabled {
 					println("received [DONE], stopping scanner")
 				}
@@ -264,20 +275,25 @@ func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon
 		if err := scanner.Err(); err != nil {
 			if err != io.EOF {
 				logger.LogError(c, "scanner error: "+err.Error())
+				info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonScannerErr, err)
 			}
 		}
+		info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonEOF, nil)
 	})
 
 	// 主循环等待完成或超时
 	select {
 	case <-ticker.C:
-		// 超时处理逻辑
-		logger.LogError(c, "streaming timeout")
+		info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonTimeout, nil)
 	case <-stopChan:
-		// 正常结束
-		logger.LogInfo(c, "streaming finished")
+		// EndReason already set by the goroutine that triggered stopChan
 	case <-c.Request.Context().Done():
-		// 客户端断开连接
-		logger.LogInfo(c, "client disconnected")
+		info.StreamStatus.SetEndReason(relaycommon.StreamEndReasonClientGone, c.Request.Context().Err())
+	}
+
+	if info.StreamStatus.IsNormalEnd() && !info.StreamStatus.HasErrors() {
+		logger.LogInfo(c, fmt.Sprintf("stream ended: %s", info.StreamStatus.Summary()))
+	} else {
+		logger.LogError(c, fmt.Sprintf("stream ended: %s, received=%d", info.StreamStatus.Summary(), info.ReceivedResponseCount))
 	}
 }

relay/helper/stream_scanner_test.go

@@ -56,8 +56,6 @@ func buildSSEBody(n int) string {
 	return b.String()
 }
 
-// slowReader wraps a reader and injects a delay before each Read call,
-// simulating a slow upstream that trickles data.
 type slowReader struct {
 	r     io.Reader
 	delay time.Duration
@@ -79,7 +77,7 @@ func TestStreamScannerHandler_NilInputs(t *testing.T) {
 
 	info := &relaycommon.RelayInfo{ChannelMeta: &relaycommon.ChannelMeta{}}
 
-	StreamScannerHandler(c, nil, info, func(data string) bool { return true })
+	StreamScannerHandler(c, nil, info, func(data string, sr *StreamResult) {})
 	StreamScannerHandler(c, &http.Response{Body: io.NopCloser(strings.NewReader(""))}, info, nil)
 }
 
@@ -89,9 +87,8 @@ func TestStreamScannerHandler_EmptyBody(t *testing.T) {
 	c, resp, info := setupStreamTest(t, strings.NewReader(""))
 
 	var called atomic.Bool
-	StreamScannerHandler(c, resp, info, func(data string) bool {
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 		called.Store(true)
-		return true
 	})
 
 	assert.False(t, called.Load(), "handler should not be called for empty body")
@@ -105,9 +102,8 @@ func TestStreamScannerHandler_1000Chunks(t *testing.T) {
 	c, resp, info := setupStreamTest(t, strings.NewReader(body))
 
 	var count atomic.Int64
-	StreamScannerHandler(c, resp, info, func(data string) bool {
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 		count.Add(1)
-		return true
 	})
 
 	assert.Equal(t, int64(numChunks), count.Load())
@@ -124,9 +120,8 @@ func TestStreamScannerHandler_10000Chunks(t *testing.T) {
 	var count atomic.Int64
 	start := time.Now()
 
-	StreamScannerHandler(c, resp, info, func(data string) bool {
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 		count.Add(1)
-		return true
 	})
 
 	elapsed := time.Since(start)
@@ -145,11 +140,10 @@ func TestStreamScannerHandler_OrderPreserved(t *testing.T) {
 	var mu sync.Mutex
 	received := make([]string, 0, numChunks)
 
-	StreamScannerHandler(c, resp, info, func(data string) bool {
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 		mu.Lock()
 		received = append(received, data)
 		mu.Unlock()
-		return true
 	})
 
 	require.Equal(t, numChunks, len(received))
@@ -166,31 +160,32 @@ func TestStreamScannerHandler_DoneStopsScanner(t *testing.T) {
 	c, resp, info := setupStreamTest(t, strings.NewReader(body))
 
 	var count atomic.Int64
-	StreamScannerHandler(c, resp, info, func(data string) bool {
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 		count.Add(1)
-		return true
 	})
 
 	assert.Equal(t, int64(50), count.Load(), "data after [DONE] must not be processed")
 }
 
-func TestStreamScannerHandler_HandlerFailureStops(t *testing.T) {
+func TestStreamScannerHandler_StopStopsStream(t *testing.T) {
 	t.Parallel()
 
 	const numChunks = 200
 	body := buildSSEBody(numChunks)
 	c, resp, info := setupStreamTest(t, strings.NewReader(body))
 
-	const failAt = 50
+	const stopAt int64 = 50
 	var count atomic.Int64
-	StreamScannerHandler(c, resp, info, func(data string) bool {
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 		n := count.Add(1)
-		return n < failAt
+		if n >= stopAt {
+			sr.Stop(fmt.Errorf("fatal at %d", n))
+		}
 	})
 
-	// The worker stops at failAt; the scanner may have read ahead,
-	// but the handler should not be called beyond failAt.
-	assert.Equal(t, int64(failAt), count.Load())
+	assert.Equal(t, stopAt, count.Load())
+	require.NotNil(t, info.StreamStatus)
+	assert.Equal(t, relaycommon.StreamEndReasonHandlerStop, info.StreamStatus.EndReason)
 }
 
 func TestStreamScannerHandler_SkipsNonDataLines(t *testing.T) {
@@ -210,9 +205,8 @@ func TestStreamScannerHandler_SkipsNonDataLines(t *testing.T) {
 	c, resp, info := setupStreamTest(t, strings.NewReader(b.String()))
 
 	var count atomic.Int64
-	StreamScannerHandler(c, resp, info, func(data string) bool {
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 		count.Add(1)
-		return true
 	})
 
 	assert.Equal(t, int64(100), count.Load())
@@ -225,25 +219,18 @@ func TestStreamScannerHandler_DataWithExtraSpaces(t *testing.T) {
 	c, resp, info := setupStreamTest(t, strings.NewReader(body))
 
 	var got string
-	StreamScannerHandler(c, resp, info, func(data string) bool {
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 		got = data
-		return true
 	})
 
 	assert.Equal(t, "{\"trimmed\":true}", got)
 }
 
-// ---------- Decoupling: scanner not blocked by slow handler ----------
+// ---------- Decoupling ----------
 
 func TestStreamScannerHandler_ScannerDecoupledFromSlowHandler(t *testing.T) {
 	t.Parallel()
 
-	// Strategy: use a slow upstream (io.Pipe, 10ms per chunk) AND a slow handler (20ms per chunk).
-	// If the scanner were synchronously coupled to the handler, total time would be
-	// ~numChunks * (10ms + 20ms) = 30ms * 50 = 1500ms.
-	// With decoupling, total time should be closer to
-	// ~numChunks * max(10ms, 20ms) = 20ms * 50 = 1000ms
-	// because the scanner reads ahead into the buffer while the handler processes.
 	const numChunks = 50
 	const upstreamDelay = 10 * time.Millisecond
 	const handlerDelay = 20 * time.Millisecond
@@ -273,10 +260,9 @@ func TestStreamScannerHandler_ScannerDecoupledFromSlowHandler(t *testing.T) {
 	start := time.Now()
 	done := make(chan struct{})
 	go func() {
-		StreamScannerHandler(c, resp, info, func(data string) bool {
+		StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 			time.Sleep(handlerDelay)
 			count.Add(1)
-			return true
 		})
 		close(done)
 	}()
@@ -293,7 +279,6 @@ func TestStreamScannerHandler_ScannerDecoupledFromSlowHandler(t *testing.T) {
 	coupledTime := time.Duration(numChunks) * (upstreamDelay + handlerDelay)
 	t.Logf("elapsed=%v, coupled_estimate=%v", elapsed, coupledTime)
 
-	// If decoupled, elapsed should be well under the coupled estimate.
 	assert.Less(t, elapsed, coupledTime*85/100,
 		"decoupled elapsed time (%v) should be significantly less than coupled estimate (%v)", elapsed, coupledTime)
 }
@@ -311,9 +296,8 @@ func TestStreamScannerHandler_SlowUpstreamFastHandler(t *testing.T) {
 
 	done := make(chan struct{})
 	go func() {
-		StreamScannerHandler(c, resp, info, func(data string) bool {
+		StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 			count.Add(1)
-			return true
 		})
 		close(done)
 	}()
@@ -344,8 +328,6 @@ func TestStreamScannerHandler_PingSentDuringSlowUpstream(t *testing.T) {
 		setting.PingIntervalSeconds = oldSeconds
 	})
 
-	// Create a reader that delivers data slowly: one chunk every 500ms over 3.5 seconds.
-	// The ping interval is 1s, so we should see at least 2 pings.
 	pr, pw := io.Pipe()
 	go func() {
 		defer pw.Close()
@@ -372,9 +354,8 @@ func TestStreamScannerHandler_PingSentDuringSlowUpstream(t *testing.T) {
 	var count atomic.Int64
 	done := make(chan struct{})
 	go func() {
-		StreamScannerHandler(c, resp, info, func(data string) bool {
+		StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 			count.Add(1)
-			return true
 		})
 		close(done)
 	}()
@@ -436,9 +417,8 @@ func TestStreamScannerHandler_PingDisabledByRelayInfo(t *testing.T) {
 	var count atomic.Int64
 	done := make(chan struct{})
 	go func() {
-		StreamScannerHandler(c, resp, info, func(data string) bool {
+		StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 			count.Add(1)
-			return true
 		})
 		close(done)
 	}()
@@ -456,6 +436,199 @@ func TestStreamScannerHandler_PingDisabledByRelayInfo(t *testing.T) {
 	assert.Equal(t, 0, pingCount, "pings should be disabled when DisablePing=true")
 }
 
+// ---------- StreamStatus integration ----------
+
+func TestStreamScannerHandler_StreamStatus_DoneReason(t *testing.T) {
+	t.Parallel()
+
+	body := buildSSEBody(10)
+	c, resp, info := setupStreamTest(t, strings.NewReader(body))
+
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {})
+
+	require.NotNil(t, info.StreamStatus)
+	assert.Equal(t, relaycommon.StreamEndReasonDone, info.StreamStatus.EndReason)
+	assert.Nil(t, info.StreamStatus.EndError)
+	assert.True(t, info.StreamStatus.IsNormalEnd())
+	assert.False(t, info.StreamStatus.HasErrors())
+}
+
+func TestStreamScannerHandler_StreamStatus_EOFWithoutDone(t *testing.T) {
+	t.Parallel()
+
+	var b strings.Builder
+	for i := 0; i < 5; i++ {
+		fmt.Fprintf(&b, "data: {\"id\":%d}\n", i)
+	}
+	c, resp, info := setupStreamTest(t, strings.NewReader(b.String()))
+
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {})
+
+	require.NotNil(t, info.StreamStatus)
+	assert.Equal(t, relaycommon.StreamEndReasonEOF, info.StreamStatus.EndReason)
+	assert.True(t, info.StreamStatus.IsNormalEnd())
+}
+
+func TestStreamScannerHandler_StreamStatus_HandlerStop(t *testing.T) {
+	t.Parallel()
+
+	body := buildSSEBody(100)
+	c, resp, info := setupStreamTest(t, strings.NewReader(body))
+
+	var count atomic.Int64
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
+		n := count.Add(1)
+		if n >= 10 {
+			sr.Stop(fmt.Errorf("stop at 10"))
+		}
+	})
+
+	require.NotNil(t, info.StreamStatus)
+	assert.Equal(t, relaycommon.StreamEndReasonHandlerStop, info.StreamStatus.EndReason)
+	assert.True(t, info.StreamStatus.HasErrors())
+}
+
+func TestStreamScannerHandler_StreamStatus_HandlerDone(t *testing.T) {
+	t.Parallel()
+
+	body := buildSSEBody(20)
+	c, resp, info := setupStreamTest(t, strings.NewReader(body))
+
+	var count atomic.Int64
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
+		n := count.Add(1)
+		if n >= 5 {
+			sr.Done()
+		}
+	})
+
+	assert.Equal(t, int64(5), count.Load())
+	require.NotNil(t, info.StreamStatus)
+	assert.Equal(t, relaycommon.StreamEndReasonDone, info.StreamStatus.EndReason)
+	assert.False(t, info.StreamStatus.HasErrors())
+}
+
+func TestStreamScannerHandler_StreamStatus_Timeout(t *testing.T) {
+	// Not parallel: modifies global constant.StreamingTimeout
+	oldTimeout := constant.StreamingTimeout
+	constant.StreamingTimeout = 2
+	t.Cleanup(func() { constant.StreamingTimeout = oldTimeout })
+
+	pr, pw := io.Pipe()
+	go func() {
+		fmt.Fprint(pw, "data: {\"id\":1}\n")
+		time.Sleep(10 * time.Second)
+		pw.Close()
+	}()
+
+	recorder := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(recorder)
+	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", nil)
+
+	resp := &http.Response{Body: pr}
+	info := &relaycommon.RelayInfo{ChannelMeta: &relaycommon.ChannelMeta{}}
+
+	done := make(chan struct{})
+	go func() {
+		StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {})
+		close(done)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(15 * time.Second):
+		t.Fatal("timed out waiting for stream timeout")
+	}
+
+	require.NotNil(t, info.StreamStatus)
+	assert.Equal(t, relaycommon.StreamEndReasonTimeout, info.StreamStatus.EndReason)
+	assert.False(t, info.StreamStatus.IsNormalEnd())
+}
+
+func TestStreamScannerHandler_StreamStatus_SoftErrors(t *testing.T) {
+	t.Parallel()
+
+	body := buildSSEBody(10)
+	c, resp, info := setupStreamTest(t, strings.NewReader(body))
+
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
+		sr.Error(fmt.Errorf("soft error for chunk"))
+	})
+
+	require.NotNil(t, info.StreamStatus)
+	assert.Equal(t, relaycommon.StreamEndReasonDone, info.StreamStatus.EndReason)
+	assert.True(t, info.StreamStatus.HasErrors())
+	assert.Equal(t, 10, info.StreamStatus.TotalErrorCount())
+}
+
+func TestStreamScannerHandler_StreamStatus_MultipleErrorsPerChunk(t *testing.T) {
+	t.Parallel()
+
+	body := buildSSEBody(5)
+	c, resp, info := setupStreamTest(t, strings.NewReader(body))
+
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
+		sr.Error(fmt.Errorf("error A"))
+		sr.Error(fmt.Errorf("error B"))
+	})
+
+	require.NotNil(t, info.StreamStatus)
+	assert.Equal(t, relaycommon.StreamEndReasonDone, info.StreamStatus.EndReason)
+	assert.Equal(t, 10, info.StreamStatus.TotalErrorCount())
+}
+
+func TestStreamScannerHandler_StreamStatus_ErrorThenStop(t *testing.T) {
+	t.Parallel()
+
+	// Use a large body without [DONE] to avoid race between scanner's [DONE]
+	// and handler's Stop on the sync.Once EndReason.
+	var b strings.Builder
+	for i := 0; i < 100; i++ {
+		fmt.Fprintf(&b, "data: {\"id\":%d}\n", i)
+	}
+	c, resp, info := setupStreamTest(t, strings.NewReader(b.String()))
+
+	var count atomic.Int64
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
+		count.Add(1)
+		sr.Error(fmt.Errorf("soft error"))
+		sr.Stop(fmt.Errorf("fatal"))
+	})
+
+	assert.Equal(t, int64(1), count.Load())
+	require.NotNil(t, info.StreamStatus)
+	assert.Equal(t, relaycommon.StreamEndReasonHandlerStop, info.StreamStatus.EndReason)
+	assert.Equal(t, 2, info.StreamStatus.TotalErrorCount())
+}
+
+func TestStreamScannerHandler_StreamStatus_InitializedIfNil(t *testing.T) {
+	t.Parallel()
+
+	body := buildSSEBody(1)
+	c, resp, info := setupStreamTest(t, strings.NewReader(body))
+
+	assert.Nil(t, info.StreamStatus)
+
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {})
+
+	assert.NotNil(t, info.StreamStatus)
+}
+
+func TestStreamScannerHandler_StreamStatus_PreInitialized(t *testing.T) {
+	t.Parallel()
+
+	body := buildSSEBody(5)
+	c, resp, info := setupStreamTest(t, strings.NewReader(body))
+
+	info.StreamStatus = relaycommon.NewStreamStatus()
+	info.StreamStatus.RecordError("pre-existing error")
+
+	StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {})
+
+	assert.Equal(t, relaycommon.StreamEndReasonDone, info.StreamStatus.EndReason)
+	assert.Equal(t, 1, info.StreamStatus.TotalErrorCount())
+}
+
 func TestStreamScannerHandler_PingInterleavesWithSlowUpstream(t *testing.T) {
 	t.Parallel()
 
@@ -469,9 +642,6 @@ func TestStreamScannerHandler_PingInterleavesWithSlowUpstream(t *testing.T) {
 		setting.PingIntervalSeconds = oldSeconds
 	})
 
-	// Slow upstream + slow handler. Total stream takes ~5 seconds.
-	// The ping goroutine stays alive as long as the scanner is reading,
-	// so pings should fire between data writes.
 	pr, pw := io.Pipe()
 	go func() {
 		defer pw.Close()
@@ -498,9 +668,8 @@ func TestStreamScannerHandler_PingInterleavesWithSlowUpstream(t *testing.T) {
 	var count atomic.Int64
 	done := make(chan struct{})
 	go func() {
-		StreamScannerHandler(c, resp, info, func(data string) bool {
+		StreamScannerHandler(c, resp, info, func(data string, sr *StreamResult) {
 			count.Add(1)
-			return true
 		})
 		close(done)
 	}()