diff --git a/internal/translator/openai/openai/responses/openai_openai-responses_request.go b/internal/translator/openai/openai/responses/openai_openai-responses_request.go
index 76b28acf..bc7027cd 100644
--- a/internal/translator/openai/openai/responses/openai_openai-responses_request.go
+++ b/internal/translator/openai/openai/responses/openai_openai-responses_request.go
@@ -154,6 +154,9 @@ func ConvertOpenAIResponsesRequestToOpenAIChatCompletions(modelName string, inpu
 							imageURL := contentItem.Get("image_url").String()
 							contentPart := []byte(`{"type":"image_url","image_url":{"url":""}}`)
 							contentPart, _ = sjson.SetBytes(contentPart, "image_url.url", imageURL)
+							if detail := contentItem.Get("detail"); detail.Exists() {
+								contentPart, _ = sjson.SetBytes(contentPart, "image_url.detail", detail.String())
+							}
 							message, _ = sjson.SetRawBytes(message, "content.-1", contentPart)
 						}
 						return true
diff --git a/internal/translator/openai/openai/responses/openai_openai-responses_request_test.go b/internal/translator/openai/openai/responses/openai_openai-responses_request_test.go
index 56bc5686..2a0f3dcd 100644
--- a/internal/translator/openai/openai/responses/openai_openai-responses_request_test.go
+++ b/internal/translator/openai/openai/responses/openai_openai-responses_request_test.go
@@ -198,3 +198,31 @@ func TestConvertOpenAIResponsesRequestToOpenAIChatCompletions_PreservesStructure
 		t.Fatalf("tool_choice.function.name = %q, want run_command; output=%s", got, out)
 	}
 }
+
+func TestConvertOpenAIResponsesRequestToOpenAIChatCompletions_PreservesInputImageDetail(t *testing.T) {
+	raw := []byte(`{
+		"input": [
+			{
+				"role": "user",
+				"content": [
+					{
+						"type": "input_image",
+						"image_url": "https://example.com/image.png",
+						"detail": "high"
+					}
+				]
+			}
+		]
+	}`)
+	t.Logf("input json:\n%s", prettyJSONForTest(raw))
+
+	out := ConvertOpenAIResponsesRequestToOpenAIChatCompletions("gpt-5.4", raw, false)
+	t.Logf("output json:\n%s", prettyJSONForTest(out))
+
+	if got := gjson.GetBytes(out, "messages.0.content.0.image_url.url").String(); got != "https://example.com/image.png" {
+		t.Fatalf("messages.0.content.0.image_url.url = %q, want https://example.com/image.png; output=%s", got, out)
+	}
+	if got := gjson.GetBytes(out, "messages.0.content.0.image_url.detail").String(); got != "high" {
+		t.Fatalf("messages.0.content.0.image_url.detail = %q, want high; output=%s", got, out)
+	}
+}