diff --git a/backend/internal/service/admin_group.go b/backend/internal/service/admin_group.go
index 9e29c30eaa..032c7024bc 100644
--- a/backend/internal/service/admin_group.go
+++ b/backend/internal/service/admin_group.go
@@ -295,6 +295,18 @@ func groupSupportsOAuthOnlyFilter(platform string) bool {
 		platform == PlatformComposite
 }
 
+func groupSupportsOpenAIFast(platform string) bool {
+	return platform == PlatformOpenAI || platform == PlatformComposite
+}
+
+func sanitizeGroupOpenAIFast(group *Group) {
+	if group == nil || !groupSupportsOpenAIFast(group.Platform) {
+		if group != nil {
+			group.ForceOpenAIFast = false
+		}
+	}
+}
+
 func (s *adminServiceImpl) CreateGroup(ctx context.Context, input *CreateGroupInput) (*Group, error) {
 	if input.RateMultiplier <= 0 {
 		return nil, errors.New("rate_multiplier must be > 0")
@@ -500,6 +512,7 @@ func (s *adminServiceImpl) CreateGroup(ctx context.Context, input *CreateGroupIn
 		SupportedModelScopes:            input.SupportedModelScopes,
 		AllowMessagesDispatch:           input.AllowMessagesDispatch,
 		AllowLive:                       input.AllowLive,
+		ForceOpenAIFast:                 input.ForceOpenAIFast,
 		RequireOAuthOnly:                input.RequireOAuthOnly,
 		RequirePrivacySet:               input.RequirePrivacySet,
 		DefaultMappedModel:              input.DefaultMappedModel,
@@ -510,6 +523,7 @@ func (s *adminServiceImpl) CreateGroup(ctx context.Context, input *CreateGroupIn
 		ReasoningEffortMappings:         reasoningEffortMappings,
 	}
 	sanitizeGroupMessagesDispatchFields(group)
+	sanitizeGroupOpenAIFast(group)
 	if group.Platform != PlatformOpenAI && group.Platform != PlatformComposite {
 		group.AllowLive = false
 	}
@@ -862,6 +876,9 @@ func (s *adminServiceImpl) UpdateGroup(ctx context.Context, id int64, input *Upd
 	if input.AllowLive != nil {
 		group.AllowLive = *input.AllowLive
 	}
+	if input.ForceOpenAIFast != nil {
+		group.ForceOpenAIFast = *input.ForceOpenAIFast
+	}
 	if input.RequireOAuthOnly != nil {
 		group.RequireOAuthOnly = *input.RequireOAuthOnly
 	}
@@ -895,6 +912,7 @@ func (s *adminServiceImpl) UpdateGroup(ctx context.Context, id int64, input *Upd
 		group.ReasoningEffortMappings = reasoningEffortMappings
 	}
 	sanitizeGroupMessagesDispatchFields(group)
+	sanitizeGroupOpenAIFast(group)
 	if group.Platform != PlatformOpenAI && group.Platform != PlatformComposite {
 		group.AllowLive = false
 	}
diff --git a/backend/internal/service/admin_service_group_test.go b/backend/internal/service/admin_service_group_test.go
index 72c5e9a0f7..02694cdfde 100644
--- a/backend/internal/service/admin_service_group_test.go
+++ b/backend/internal/service/admin_service_group_test.go
@@ -1082,6 +1082,66 @@ func TestAdminService_CreateCompositeGroupPreservesLive(t *testing.T) {
 	require.True(t, repo.created.AllowLive)
 }
 
+func TestAdminService_CreateGroup_NormalizesForceOpenAIFastByPlatform(t *testing.T) {
+	for _, tt := range []struct {
+		name     string
+		platform string
+		want     bool
+	}{
+		{name: "openai", platform: PlatformOpenAI, want: true},
+		{name: "composite", platform: PlatformComposite, want: true},
+		{name: "anthropic", platform: PlatformAnthropic, want: false},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			repo := &groupRepoStubForAdmin{}
+			svc := &adminServiceImpl{groupRepo: repo}
+
+			group, err := svc.CreateGroup(context.Background(), &CreateGroupInput{
+				Name: "fast-" + tt.name, Platform: tt.platform, RateMultiplier: 1, ForceOpenAIFast: true,
+			})
+
+			require.NoError(t, err)
+			require.NotNil(t, group)
+			require.Equal(t, tt.want, repo.created.ForceOpenAIFast)
+		})
+	}
+}
+
+func TestAdminService_UpdateGroup_ClearsForceOpenAIFastWhenPlatformChanges(t *testing.T) {
+	existingGroup := &Group{
+		ID: 1, Name: "existing-fast", Platform: PlatformOpenAI, Status: StatusActive, ForceOpenAIFast: true,
+	}
+	repo := &groupRepoStubForAdmin{getByID: existingGroup}
+	svc := &adminServiceImpl{groupRepo: repo}
+
+	group, err := svc.UpdateGroup(context.Background(), existingGroup.ID, &UpdateGroupInput{
+		Platform: PlatformAnthropic,
+	})
+
+	require.NoError(t, err)
+	require.NotNil(t, group)
+	require.False(t, repo.updated.ForceOpenAIFast)
+}
+
+func TestAdminService_UpdateGroup_ForceOpenAIFastInvalidatesAuthCache(t *testing.T) {
+	existingGroup := &Group{
+		ID: 1, Name: "existing-fast", Platform: PlatformOpenAI, Status: StatusActive,
+	}
+	repo := &groupRepoStubForAdmin{getByID: existingGroup}
+	invalidator := &authCacheInvalidatorStub{}
+	svc := &adminServiceImpl{groupRepo: repo, authCacheInvalidator: invalidator}
+	enabled := true
+
+	group, err := svc.UpdateGroup(context.Background(), existingGroup.ID, &UpdateGroupInput{
+		ForceOpenAIFast: &enabled,
+	})
+
+	require.NoError(t, err)
+	require.NotNil(t, group)
+	require.True(t, repo.updated.ForceOpenAIFast)
+	require.Equal(t, []int64{existingGroup.ID}, invalidator.groupIDs)
+}
+
 func TestAdminService_UpdateCompositeGroupPreservesLive(t *testing.T) {
 	existingGroup := &Group{
 		ID:       1,