From 0b09523bbeb8ee7705977dff7781748b08fca775 Mon Sep 17 00:00:00 2001
From: Dean Chen <862469039@qq.com>
Date: Mon, 26 Oct 2026 06:26:05 +0500
Subject: [PATCH] fix(runtime): keep text sent with a terminal finish reason

Some OpenAI-compatible providers put the last content delta in the same
chunk as finish_reason "stop" or "length". The stream handler returned
on the finish reason before appending that chunk's content and
reasoning, so the end of the answer was dropped.

Accumulate reasoning, thinking signature and content before handling
the terminal finish reason.

Fixes #4715

Signed-off-by: Dean Chen <862469039@qq.com>
---
 pkg/runtime/streaming.go      | 37 +++++++++++++++++++----------------
 pkg/runtime/streaming_test.go | 37 +++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 17 deletions(-)

diff --git a/pkg/runtime/streaming.go b/pkg/runtime/streaming.go
index 1b69e27e50..30ca571cd4 100644
--- a/pkg/runtime/streaming.go
+++ b/pkg/runtime/streaming.go
@@ -356,6 +356,26 @@ mainLoop:
 				}
 			}
 
+			// Text in a terminal chunk belongs to the answer too: some
+			// OpenAI-compatible providers send the last delta together with
+			// finish_reason, so accumulate it before the early return below.
+			if choice.Delta.ReasoningContent != "" {
+				responseStarted = true
+				events.Emit(AgentChoiceReasoning(a.Name(), sess.ID, choice.Delta.ReasoningContent, messageID))
+				fullReasoningContent.WriteString(choice.Delta.ReasoningContent)
+			}
+
+			// Capture thinking signature for Anthropic extended thinking
+			if choice.Delta.ThinkingSignature != "" {
+				responseStarted = true
+				thinkingSignature = choice.Delta.ThinkingSignature
+			}
+
+			if choice.Delta.Content != "" {
+				responseStarted = true
+				appendContent(markerFilter.Push(choice.Delta.Content))
+			}
+
 			if choice.FinishReason == chat.FinishReasonStop || choice.FinishReason == chat.FinishReasonLength || choice.FinishReason == chat.FinishReasonRefusal {
 				finishAssistantText()
 				recordUsage()
@@ -403,23 +423,6 @@ mainLoop:
 				providerFinishReason = choice.FinishReason
 			}
 
-			if choice.Delta.ReasoningContent != "" {
-				responseStarted = true
-				events.Emit(AgentChoiceReasoning(a.Name(), sess.ID, choice.Delta.ReasoningContent, messageID))
-				fullReasoningContent.WriteString(choice.Delta.ReasoningContent)
-			}
-
-			// Capture thinking signature for Anthropic extended thinking
-			if choice.Delta.ThinkingSignature != "" {
-				responseStarted = true
-				thinkingSignature = choice.Delta.ThinkingSignature
-			}
-
-			if choice.Delta.Content != "" {
-				responseStarted = true
-				appendContent(markerFilter.Push(choice.Delta.Content))
-			}
-
 		case <-ctx.Done():
 			// Context cancelled (SIGTERM, Ctrl+C, or idle-timeout cancel from
 			// this function). Return promptly so graceful shutdown can proceed.
diff --git a/pkg/runtime/streaming_test.go b/pkg/runtime/streaming_test.go
index 4422c8684a..a344143b1e 100644
--- a/pkg/runtime/streaming_test.go
+++ b/pkg/runtime/streaming_test.go
@@ -216,6 +216,43 @@ func TestHandleStream_ToolCallThenSeparateStop(t *testing.T) {
 	assert.False(t, res.Stopped)
 }
 
+// TestHandleStream_ContentInTerminalChunk covers providers that send the last
+// text delta in the same chunk as the terminal finish_reason: that text must
+// end up in the result and in the live events instead of being dropped.
+func TestHandleStream_ContentInTerminalChunk(t *testing.T) {
+	t.Parallel()
+
+	for _, reason := range []chat.FinishReason{chat.FinishReasonStop, chat.FinishReasonLength} {
+		t.Run(string(reason), func(t *testing.T) {
+			t.Parallel()
+
+			b := newStreamBuilder().
+				AddReasoning("thinking ").
+				AddContent("M").
+				AddContent("1-deepseek-v4")
+			b.responses = append(b.responses, chat.MessageStreamResponse{
+				Choices: []chat.MessageStreamChoice{{
+					Index:        0,
+					FinishReason: reason,
+					Delta: chat.MessageDelta{
+						Content:          ".1-flash",
+						ReasoningContent: "done",
+					},
+				}},
+				Usage: &chat.Usage{InputTokens: 1, OutputTokens: 1},
+			})
+
+			res, live := runMarkerStream(t, b.Build())
+
+			assert.Equal(t, "M1-deepseek-v4.1-flash", res.Content)
+			assert.Equal(t, res.Content, live)
+			assert.Equal(t, "thinking done", res.ReasoningContent)
+			assert.Equal(t, reason, res.FinishReason)
+			assert.True(t, res.Stopped)
+		})
+	}
+}
+
 // TestHandleStream_MediaAccumulatesAlongsideText verifies that a
 // generated-media delta streamed alongside text is accumulated into
 // streamResult.Media without disturbing the existing text/finish-reason