fix(canvas): 视频首尾帧 - 保留结构化帧并按协议顺序传参

backend/internal/service/provider.go

@@ -1148,6 +1148,13 @@ func newAPIChannel2VideoBody(input canvasGenerationInput) (map[string]interface{
 			return nil, fmt.Errorf("NewAPI Video Generations 的 %s 必须且只能提供 1 张参考图（当前 %d 张）", input.Config.Model, len(images))
 		}
 	}
+	frameImages, err := videoFrameImageURLs(input, images)
+	if err != nil {
+		return nil, err
+	}
+	if len(frameImages) > 0 {
+		images = frameImages
+	}
 
 	seconds, secondsErr := strconv.Atoi(strings.TrimSpace(input.Config.VideoSeconds))
 	if secondsErr != nil || seconds < 1 {
@@ -2066,7 +2073,11 @@ func seedanceVideosBody(input canvasGenerationInput) (map[string]interface{}, er
 		}
 		imageURLs = append(imageURLs, url)
 	}
-	if frameImageURLs := seedanceVideosFrameImageURLs(input, imageURLs); len(frameImageURLs) > 0 {
+	frameImageURLs, err := videoFrameImageURLs(input, imageURLs)
+	if err != nil {
+		return nil, err
+	}
+	if len(frameImageURLs) > 0 {
 		body["image_urls"] = frameImageURLs
 	} else if len(imageURLs) > 0 {
 		body["image_url"] = imageURLs[0]
@@ -2117,36 +2128,41 @@ func seedanceImageRole(input canvasGenerationInput, image providerMedia) string
 	return "reference_image"
 }
 
-func seedanceVideosFrameImageURLs(input canvasGenerationInput, imageURLs []string) []string {
+func videoFrameImageURLs(input canvasGenerationInput, imageURLs []string) ([]string, error) {
 	startFrameID := metadataString(input.Metadata, "videoStartFrameNodeId")
 	endFrameID := metadataString(input.Metadata, "videoEndFrameNodeId")
 	if startFrameID == "" && endFrameID == "" {
-		return nil
+		return nil, nil
 	}
-	// /v1/videos 的 image_urls 只接受字符串；首帧和尾帧通过数组顺序表达。
+	// image_urls 按首帧、尾帧、普通参考图排序，保持 JSON 视频协议的结构化帧语义。
 	ordered := make([]string, 0, len(imageURLs))
 	used := make([]bool, len(imageURLs))
-	appendFrame := func(frameID string) {
+	appendFrame := func(frameID string, label string) error {
 		if frameID == "" {
-			return
+			return nil
 		}
 		for index, image := range input.ReferenceImages {
-			if index >= len(imageURLs) || used[index] || image.ID != frameID {
+			if index >= len(imageURLs) || image.ID != frameID {
 				continue
 			}
 			ordered = append(ordered, imageURLs[index])
 			used[index] = true
-			return
+			return nil
 		}
+		return fmt.Errorf("已配置的%s参考图未包含在视频请求中", label)
+	}
+	if err := appendFrame(startFrameID, "首帧"); err != nil {
+		return nil, err
+	}
+	if err := appendFrame(endFrameID, "尾帧"); err != nil {
+		return nil, err
 	}
-	appendFrame(startFrameID)
-	appendFrame(endFrameID)
 	for index, imageURL := range imageURLs {
 		if !used[index] {
 			ordered = append(ordered, imageURL)
 		}
 	}
-	return ordered
+	return ordered, nil
 }
 
 func metadataString(metadata map[string]interface{}, key string) string {

backend/internal/service/provider_test.go

@@ -8,6 +8,7 @@ import (
 	"mime/multipart"
 	"net/http"
 	"net/http/httptest"
+	"reflect"
 	"strconv"
 	"strings"
 	"testing"
@@ -915,6 +916,37 @@ func TestNewAPIChannel2SingleImageModelUsesReferenceForStaleTextToVideoMetadata(
 	}
 }
 
+func TestNewAPIChannel2OrdersFramesBeforeReferenceImages(t *testing.T) {
+	body, err := newAPIChannel2VideoBody(canvasGenerationInput{
+		Config: providerConfig{Model: "Seedance 2 Mini", VideoSeconds: "10"},
+		ReferenceImages: []providerMedia{
+			{ID: "character", DataURL: "data:image/png;base64,Y2hhcmFjdGVy"},
+			{ID: "last-frame", DataURL: "data:image/png;base64,bGFzdA=="},
+			{ID: "first-frame", DataURL: "data:image/png;base64,Zmlyc3Q="},
+		},
+		Metadata: map[string]interface{}{"videoStartFrameNodeId": "first-frame", "videoEndFrameNodeId": "last-frame", "videoEditOperation": "image_to_video"},
+	})
+	if err != nil {
+		t.Fatalf("newAPIChannel2VideoBody() error = %v", err)
+	}
+	images, ok := body["image_urls"].([]string)
+	want := []string{"data:image/png;base64,Zmlyc3Q=", "data:image/png;base64,bGFzdA==", "data:image/png;base64,Y2hhcmFjdGVy"}
+	if !ok || !reflect.DeepEqual(images, want) {
+		t.Fatalf("image_urls = %#v, want %#v", body["image_urls"], want)
+	}
+}
+
+func TestNewAPIChannel2RejectsMissingConfiguredFrame(t *testing.T) {
+	_, err := newAPIChannel2VideoBody(canvasGenerationInput{
+		Config:          providerConfig{Model: "Seedance 2 Mini", VideoSeconds: "10"},
+		ReferenceImages: []providerMedia{{ID: "character", DataURL: testReferenceImageDataURL}},
+		Metadata:        map[string]interface{}{"videoStartFrameNodeId": "missing-frame", "videoEditOperation": "image_to_video"},
+	})
+	if err == nil || !strings.Contains(err.Error(), "首帧参考图未包含") {
+		t.Fatalf("newAPIChannel2VideoBody() error = %v", err)
+	}
+}
+
 func TestValidateGenerationInterfaceRejectsMismatchedType(t *testing.T) {
 	if err := validateGenerationInterface("video", "chat-completion"); err == nil {
 		t.Fatal("validateGenerationInterface() error = nil")