fix(images): 兼容 OpenAI 多图编辑 multipart

- 将 OpenAI images/edits 请求构造成 multipart/form-data
- 在运行时安全转存 URL 图片为 data URL 后提交二进制文件
- 覆盖多图字段、真实上游模型名和内部元数据过滤测试

apps/api/internal/runner/request_assets.go

@@ -160,6 +160,9 @@ func (s *Service) hydrateProviderRequestAssetString(ctx context.Context, value s
 		return value, nil
 	}
 	style, ok := requestAssetCapabilityHydrationForMedia("image", candidate, raw, "")
+	if !ok && openAIImageEditRequiresMultipartBytes(candidate) {
+		style, ok = requestAssetHydrateDataURL, true
+	}
 	if !ok {
 		return value, nil
 	}
@@ -320,6 +323,9 @@ func requestAssetHydrationForField(path []string, asset store.RequestAsset, cand
 		if style, ok := requestAssetCapabilityHydrationForMedia("image", candidate, asset.URL, asset.StorageProvider); ok {
 			return style
 		}
+		if openAIImageEditRequiresMultipartBytes(candidate) {
+			return requestAssetHydrateDataURL
+		}
 	}
 	if mediaURLFieldNeedsHydration(path) {
 		if style := configuredRequestAssetMediaURLHydration(candidate, requestAssetMediaURLKind(path)); style != "" {
@@ -332,6 +338,11 @@ func requestAssetHydrationForField(path []string, asset store.RequestAsset, cand
 	return requestAssetHydrateURL
 }
 
+func openAIImageEditRequiresMultipartBytes(candidate store.RuntimeModelCandidate) bool {
+	return normalizeProviderKey(candidate.Provider) == "openai" &&
+		strings.TrimSpace(candidate.ModelType) == "image_edit"
+}
+
 func requestAssetMediaKindForHydration(path []string, asset store.RequestAsset) string {
 	if mediaURLFieldNeedsHydration(path) {
 		return requestAssetMediaURLKind(path)

apps/api/internal/runner/request_assets_test.go

@@ -205,6 +205,35 @@ func TestHydrateProviderRequestAssetsUsesImageCapabilityBase64ForTopLevelImageAs
 	}
 }
 
+func TestHydrateProviderRequestAssetsConvertsOpenAIEditImagesForMultipart(t *testing.T) {
+	payload := []byte{0x89, 'P', 'N', 'G', '\r', '\n', 0x1a, '\n', 1, 2, 3, 4}
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "image/png")
+		_, _ = w.Write(payload)
+	}))
+	defer server.Close()
+	service := &Service{}
+	body := map[string]any{
+		"images": []any{
+			server.URL + "/first.png",
+			server.URL + "/second.png",
+		},
+	}
+
+	hydrated, err := service.hydrateProviderRequestAssets(context.Background(), body, store.RuntimeModelCandidate{
+		Provider:  "openai",
+		ModelType: "image_edit",
+	})
+	if err != nil {
+		t.Fatalf("hydrate OpenAI edit images: %v", err)
+	}
+	images := hydrated["images"].([]any)
+	want := "data:image/png;base64," + base64.StdEncoding.EncodeToString(payload)
+	if len(images) != 2 || stringFromAny(images[0]) != want || stringFromAny(images[1]) != want {
+		t.Fatalf("OpenAI edit images should be hydrated for multipart: %+v", images)
+	}
+}
+
 func TestHydrateProviderRequestAssetsImageCapabilityOverridesProviderDataURLDefault(t *testing.T) {
 	service := &Service{}
 	body := map[string]any{