diff --git a/backend/internal/service/admin_service_group_test.go b/backend/internal/service/admin_service_group_test.go
index 98e63899b6..c0b4faef52 100644
--- a/backend/internal/service/admin_service_group_test.go
+++ b/backend/internal/service/admin_service_group_test.go
@@ -1588,7 +1588,8 @@ func TestAdminService_CreateCompositeRoute_NormalizesAndPersists(t *testing.T) {
require.Equal(t, "router/gpt-", route.PublicModel)
require.Equal(t, CompositeRouteMatchPrefix, route.MatchType)
require.Equal(t, PlatformOpenAI, route.TargetPlatform)
- require.Equal(t, "router/gpt-", route.UpstreamModel)
+ // prefix 路由留空 upstream_model 不再回填 public_model：留空表示透传原始请求模型。
+ require.Equal(t, "", route.UpstreamModel)
require.Equal(t, CompositeRouteEndpointResponses, route.Endpoint)
require.Equal(t, 100, route.Priority)
require.True(t, route.Enabled)
@@ -1596,6 +1597,29 @@ func TestAdminService_CreateCompositeRoute_NormalizesAndPersists(t *testing.T) {
require.Equal(t, route, routeRepo.created)
}
+// TestAdminService_CreateCompositeRoute_ExactEmptyUpstreamBackfillsPublicModel 锁定
+// 保守行为：exact 路由留空 upstream_model 仍回填 public_model（持久化/展示契约不变）。
+func TestAdminService_CreateCompositeRoute_ExactEmptyUpstreamBackfillsPublicModel(t *testing.T) {
+ groupRepo := &groupRepoStubForAdmin{
+ getByID: &Group{ID: 7, Platform: PlatformComposite},
+ }
+ routeRepo := &compositeRouteRepoStubForAdmin{nextID: 99}
+ svc := &adminServiceImpl{groupRepo: groupRepo, compositeRouteRepo: routeRepo}
+
+ route, err := svc.CreateCompositeRoute(context.Background(), 7, CompositeRouteInput{
+ PublicModel: "openrouter/gpt-5",
+ MatchType: CompositeRouteMatchExact,
+ TargetPlatform: PlatformOpenAI,
+ Endpoint: CompositeRouteEndpointResponses,
+ Enabled: true,
+ })
+
+ require.NoError(t, err)
+ require.NotNil(t, route)
+ require.Equal(t, CompositeRouteMatchExact, route.MatchType)
+ require.Equal(t, "openrouter/gpt-5", route.UpstreamModel)
+}
+
func TestAdminService_UpdateAndDeleteCompositeRouteRequireRouteOwnership(t *testing.T) {
groupRepo := &groupRepoStubForAdmin{
getByID: &Group{ID: 7, Platform: PlatformComposite},
diff --git a/backend/internal/service/composite_model_route.go b/backend/internal/service/composite_model_route.go
index 2bae5c62df..a008a3e9fa 100644
--- a/backend/internal/service/composite_model_route.go
+++ b/backend/internal/service/composite_model_route.go
@@ -118,7 +118,12 @@ func normalizeCompositeRouteInput(input CompositeRouteInput) CompositeRouteInput
input.TargetPlatform = strings.TrimSpace(input.TargetPlatform)
input.UpstreamModel = strings.TrimSpace(input.UpstreamModel)
input.Endpoint = normalizeCompositeRouteEndpoint(input.Endpoint)
- if input.UpstreamModel == "" {
+ // 仅对 exact 路由把空 upstream_model 回填成 public_model：exact 命中时请求模型
+ // 恒等于 public_model，回填只影响持久化/后台展示，保留原有契约不变。
+ // prefix 路由留空则不回填——Resolve 会回退到具体请求模型，从而透传原始模型
+ // （否则 public=deepseek-v4 的前缀路由会把 deepseek-v4-flash / deepseek-v4-pro
+ // 都塌缩成固定的 deepseek-v4）。显式填写 upstream_model 时任何模式都原样固定转发。
+ if input.UpstreamModel == "" && input.MatchType == CompositeRouteMatchExact {
input.UpstreamModel = input.PublicModel
}
input.Notes = strings.TrimSpace(input.Notes)
diff --git a/backend/internal/service/composite_route_resolver_test.go b/backend/internal/service/composite_route_resolver_test.go
index ed6f6f0850..35028934dd 100644
--- a/backend/internal/service/composite_route_resolver_test.go
+++ b/backend/internal/service/composite_route_resolver_test.go
@@ -107,6 +107,63 @@ func TestCompositeRouteResolverPrefersEndpointSpecificLongestPrefix(t *testing.T
require.Equal(t, int64(2), decision.Route.ID)
}
+// TestCompositeRouteResolverPrefixEmptyUpstreamPassesThroughRequestedModel 验证：
+// 前缀匹配路由留空 upstream_model 时，转发的是具体请求模型（各自原样），而不是
+// 塌缩成 public_model。这是「留空 = 透传原始模型」语义的核心场景。
+func TestCompositeRouteResolverPrefixEmptyUpstreamPassesThroughRequestedModel(t *testing.T) {
+ resolver := NewCompositeRouteResolver(compositeRouteRepoStub{
+ routes: []CompositeModelRoute{
+ {
+ ID: 1,
+ GroupID: 7,
+ PublicModel: "deepseek-v4",
+ MatchType: CompositeRouteMatchPrefix,
+ TargetPlatform: PlatformOpenAI,
+ UpstreamModel: "", // 留空 = 透传
+ Endpoint: CompositeRouteEndpointAny,
+ Priority: 100,
+ Enabled: true,
+ },
+ },
+ })
+
+ for _, model := range []string{"deepseek-v4-flash", "deepseek-v4-pro", "deepseek-v4"} {
+ decision, err := resolver.Resolve(context.Background(), 7, model, CompositeRouteEndpointChatCompletions)
+ require.NoError(t, err)
+ require.True(t, decision.Matched, "model %q should match prefix route", model)
+ require.Equal(t, CompositeRouteSourceExplicit, decision.Source)
+ require.Equal(t, PlatformOpenAI, decision.TargetPlatform)
+ require.Equal(t, model, decision.UpstreamModel, "model %q should pass through verbatim", model)
+ }
+}
+
+// TestCompositeRouteResolverPrefixExplicitUpstreamStillFixed 验证：前缀匹配路由显式
+// 填写 upstream_model 时，所有命中请求仍转发同一个固定上游模型（行为不变）。
+func TestCompositeRouteResolverPrefixExplicitUpstreamStillFixed(t *testing.T) {
+ resolver := NewCompositeRouteResolver(compositeRouteRepoStub{
+ routes: []CompositeModelRoute{
+ {
+ ID: 1,
+ GroupID: 7,
+ PublicModel: "deepseek-v4",
+ MatchType: CompositeRouteMatchPrefix,
+ TargetPlatform: PlatformOpenAI,
+ UpstreamModel: "deepseek-chat",
+ Endpoint: CompositeRouteEndpointAny,
+ Priority: 100,
+ Enabled: true,
+ },
+ },
+ })
+
+ for _, model := range []string{"deepseek-v4-flash", "deepseek-v4-pro"} {
+ decision, err := resolver.Resolve(context.Background(), 7, model, CompositeRouteEndpointChatCompletions)
+ require.NoError(t, err)
+ require.True(t, decision.Matched)
+ require.Equal(t, "deepseek-chat", decision.UpstreamModel)
+ }
+}
+
func TestCompositeRouteResolverIgnoresDisabledRoutesAndFallsBackToDetector(t *testing.T) {
resolver := NewCompositeRouteResolver(compositeRouteRepoStub{
routes: []CompositeModelRoute{
diff --git a/frontend/src/i18n/locales/en/admin/overview.ts b/frontend/src/i18n/locales/en/admin/overview.ts
index 1dfcec2988..67887a9f45 100644
--- a/frontend/src/i18n/locales/en/admin/overview.ts
+++ b/frontend/src/i18n/locales/en/admin/overview.ts
@@ -1031,6 +1031,7 @@ export default {
endpoint: 'Endpoint',
targetPlatform: 'Target Platform',
upstreamModel: 'Upstream Model',
+ upstreamModelHint: 'Leave empty to pass the original requested model through: under prefix match each matched model forwards verbatim (e.g. deepseek-v4-flash and deepseek-v4-pro each forwarded as-is); set a value to forward every matched request to that fixed model.',
notes: 'Notes',
enabled: 'Enabled',
preview: 'Preview',
diff --git a/frontend/src/i18n/locales/zh/admin/overview.ts b/frontend/src/i18n/locales/zh/admin/overview.ts
index ac4838105d..112577b894 100644
--- a/frontend/src/i18n/locales/zh/admin/overview.ts
+++ b/frontend/src/i18n/locales/zh/admin/overview.ts
@@ -1028,6 +1028,7 @@ export default {
endpoint: '端点',
targetPlatform: '目标平台',
upstreamModel: '上游模型',
+ upstreamModelHint: '留空表示透传原始请求模型：前缀匹配下每个命中模型各自原样转发（如 deepseek-v4-flash、deepseek-v4-pro 分别转发）；填写则所有命中请求都固定转发该模型。',
notes: '备注',
enabled: '启用',
preview: '预览',
diff --git a/frontend/src/views/admin/GroupsView.vue b/frontend/src/views/admin/GroupsView.vue
index 260628fd05..54375581b9 100644
--- a/frontend/src/views/admin/GroupsView.vue
+++ b/frontend/src/views/admin/GroupsView.vue
@@ -3886,6 +3886,9 @@
class="input"
placeholder="gpt-5"
/>
+
+ {{ t("admin.groups.compositeRoutes.upstreamModelHint") }}
+