From 872070259ef66a8d3c66d1901d397c7459e98d97 Mon Sep 17 00:00:00 2001
From: Luis Pater <webmaster@idotorg.org>
Date: Mon, 3 Aug 2026 05:37:05 +0800
Subject: [PATCH] fix(translator): emit `response.completed` on stream end when
 `finish_reason` is missing

Closes: #4745
---
 .../openai_openai-responses_response.go       | 19 ++++++++-----------
 .../openai_openai-responses_response_test.go  |  9 +++++++++
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/internal/translator/openai/openai/responses/openai_openai-responses_response.go b/internal/translator/openai/openai/responses/openai_openai-responses_response.go
index bc390f30..9d198a42 100644
--- a/internal/translator/openai/openai/responses/openai_openai-responses_response.go
+++ b/internal/translator/openai/openai/responses/openai_openai-responses_response.go
@@ -20,14 +20,13 @@ type oaiToResponsesStateReasoning struct {
 	OutputIndex   int
 }
 type oaiToResponsesState struct {
-	Seq               int
-	ResponseID        string
-	Created           int64
-	Started           bool
-	CompletionPending bool
-	CompletedEmitted  bool
-	ReasoningID       string
-	ReasoningIndex    int
+	Seq              int
+	ResponseID       string
+	Created          int64
+	Started          bool
+	CompletedEmitted bool
+	ReasoningID      string
+	ReasoningIndex   int
 	// aggregation buffers for response.output
 	// Per-output message text buffers by index
 	MsgTextBuf   map[int]*strings.Builder
@@ -246,7 +245,7 @@ func ConvertOpenAIChatCompletionsResponseToOpenAIResponses(ctx context.Context,
 	}
 	requestForNamespace := pickRequestJSON(originalRequestRawJSON, requestRawJSON)
 	if bytes.Equal(rawJSON, []byte("[DONE]")) {
-		if st.CompletionPending && !st.CompletedEmitted {
+		if st.Started && !st.CompletedEmitted {
 			st.CompletedEmitted = true
 			return [][]byte{buildResponsesCompletedEvent(st, requestForNamespace, func() int { st.Seq++; return st.Seq })}
 		}
@@ -390,7 +389,6 @@ func ConvertOpenAIChatCompletionsResponseToOpenAIResponses(ctx context.Context,
 		st.TotalTokens = 0
 		st.ReasoningTokens = 0
 		st.UsageSeen = false
-		st.CompletionPending = false
 		st.CompletedEmitted = false
 		// response.created
 		created := []byte(`{"type":"response.created","sequence_number":0,"response":{"id":"","object":"response","created_at":0,"status":"in_progress","background":false,"error":null,"output":[]}}`)
@@ -689,7 +687,6 @@ func ConvertOpenAIChatCompletionsResponseToOpenAIResponses(ctx context.Context,
 						st.FuncArgsDone[key] = true
 					}
 				}
-				st.CompletionPending = true
 			}
 
 			return true
diff --git a/internal/translator/openai/openai/responses/openai_openai-responses_response_test.go b/internal/translator/openai/openai/responses/openai_openai-responses_response_test.go
index 9898744a..80ae4b44 100644
--- a/internal/translator/openai/openai/responses/openai_openai-responses_response_test.go
+++ b/internal/translator/openai/openai/responses/openai_openai-responses_response_test.go
@@ -69,6 +69,15 @@ func TestConvertOpenAIChatCompletionsResponseToOpenAIResponses_ResponseCompleted
 			outputTokens:   5,
 			totalTokens:    18,
 		},
+		{
+			name: "no finish reason",
+			in: []string{
+				`data: {"id":"resp_no_finish_reason","object":"chat.completion.chunk","created":1773896263,"model":"model","choices":[{"index":0,"delta":{"role":"assistant","content":"hello"}}]}`,
+				`data: [DONE]`,
+			},
+			doneInputIndex: 1,
+			hasUsage:       false,
+		},
 		{
 			// An OpenAI-compatible streams from a buggy server might never send usage, so response.completed should
 			// still wait for [DONE] but omit the usage object entirely.
-- 
2.51.2