feat: add projects flow and consolidate default project handling

internal/services/configuration.go

@@ -22,17 +22,20 @@ type ConfigurationGetter interface {
 
 type ConfigurationService struct {
 	configRepo    *repository.ConfigurationRepository
+	projectRepo   *repository.ProjectRepository
 	componentRepo *repository.ComponentRepository
 	quoteService  *QuoteService
 }
 
 func NewConfigurationService(
 	configRepo *repository.ConfigurationRepository,
+	projectRepo *repository.ProjectRepository,
 	componentRepo *repository.ComponentRepository,
 	quoteService *QuoteService,
 ) *ConfigurationService {
 	return &ConfigurationService{
 		configRepo:    configRepo,
+		projectRepo:   projectRepo,
 		componentRepo: componentRepo,
 		quoteService:  quoteService,
 	}
@@ -41,6 +44,7 @@ func NewConfigurationService(
 type CreateConfigRequest struct {
 	Name        string             `json:"name"`
 	Items       models.ConfigItems `json:"items"`
+	ProjectUUID *string            `json:"project_uuid,omitempty"`
 	CustomPrice *float64           `json:"custom_price"`
 	Notes       string             `json:"notes"`
 	IsTemplate  bool               `json:"is_template"`
@@ -48,6 +52,11 @@ type CreateConfigRequest struct {
 }
 
 func (s *ConfigurationService) Create(ownerUsername string, req *CreateConfigRequest) (*models.Configuration, error) {
+	projectUUID, err := s.resolveProjectUUID(ownerUsername, req.ProjectUUID)
+	if err != nil {
+		return nil, err
+	}
+
 	total := req.Items.Total()
 
 	// If server count is greater than 1, multiply the total by server count
@@ -58,6 +67,7 @@ func (s *ConfigurationService) Create(ownerUsername string, req *CreateConfigReq
 	config := &models.Configuration{
 		UUID:          uuid.New().String(),
 		OwnerUsername: ownerUsername,
+		ProjectUUID:   projectUUID,
 		Name:          req.Name,
 		Items:         req.Items,
 		TotalPrice:    &total,
@@ -101,6 +111,11 @@ func (s *ConfigurationService) Update(uuid string, ownerUsername string, req *Cr
 		return nil, ErrConfigForbidden
 	}
 
+	projectUUID, err := s.resolveProjectUUID(ownerUsername, req.ProjectUUID)
+	if err != nil {
+		return nil, err
+	}
+
 	total := req.Items.Total()
 
 	// If server count is greater than 1, multiply the total by server count
@@ -109,6 +124,7 @@ func (s *ConfigurationService) Update(uuid string, ownerUsername string, req *Cr
 	}
 
 	config.Name = req.Name
+	config.ProjectUUID = projectUUID
 	config.Items = req.Items
 	config.TotalPrice = &total
 	config.CustomPrice = req.CustomPrice
@@ -156,10 +172,21 @@ func (s *ConfigurationService) Rename(uuid string, ownerUsername string, newName
 }
 
 func (s *ConfigurationService) Clone(configUUID string, ownerUsername string, newName string) (*models.Configuration, error) {
+	return s.CloneToProject(configUUID, ownerUsername, newName, nil)
+}
+
+func (s *ConfigurationService) CloneToProject(configUUID string, ownerUsername string, newName string, projectUUID *string) (*models.Configuration, error) {
 	original, err := s.GetByUUID(configUUID, ownerUsername)
 	if err != nil {
 		return nil, err
 	}
+	resolvedProjectUUID := original.ProjectUUID
+	if projectUUID != nil {
+		resolvedProjectUUID, err = s.resolveProjectUUID(ownerUsername, projectUUID)
+		if err != nil {
+			return nil, err
+		}
+	}
 
 	// Create copy with new UUID and name
 	total := original.Items.Total()
@@ -172,6 +199,7 @@ func (s *ConfigurationService) Clone(configUUID string, ownerUsername string, ne
 	clone := &models.Configuration{
 		UUID:          uuid.New().String(),
 		OwnerUsername: ownerUsername,
+		ProjectUUID:   resolvedProjectUUID,
 		Name:          newName,
 		Items:         original.Items,
 		TotalPrice:    &total,
@@ -229,12 +257,18 @@ func (s *ConfigurationService) UpdateNoAuth(uuid string, req *CreateConfigReques
 		return nil, ErrConfigNotFound
 	}
 
+	projectUUID, err := s.resolveProjectUUID(config.OwnerUsername, req.ProjectUUID)
+	if err != nil {
+		return nil, err
+	}
+
 	total := req.Items.Total()
 	if req.ServerCount > 1 {
 		total *= float64(req.ServerCount)
 	}
 
 	config.Name = req.Name
+	config.ProjectUUID = projectUUID
 	config.Items = req.Items
 	config.TotalPrice = &total
 	config.CustomPrice = req.CustomPrice
@@ -275,10 +309,21 @@ func (s *ConfigurationService) RenameNoAuth(uuid string, newName string) (*model
 
 // CloneNoAuth clones configuration without ownership check
 func (s *ConfigurationService) CloneNoAuth(configUUID string, newName string, ownerUsername string) (*models.Configuration, error) {
+	return s.CloneNoAuthToProject(configUUID, newName, ownerUsername, nil)
+}
+
+func (s *ConfigurationService) CloneNoAuthToProject(configUUID string, newName string, ownerUsername string, projectUUID *string) (*models.Configuration, error) {
 	original, err := s.configRepo.GetByUUID(configUUID)
 	if err != nil {
 		return nil, ErrConfigNotFound
 	}
+	resolvedProjectUUID := original.ProjectUUID
+	if projectUUID != nil {
+		resolvedProjectUUID, err = s.resolveProjectUUID(ownerUsername, projectUUID)
+		if err != nil {
+			return nil, err
+		}
+	}
 
 	total := original.Items.Total()
 	if original.ServerCount > 1 {
@@ -288,6 +333,7 @@ func (s *ConfigurationService) CloneNoAuth(configUUID string, newName string, ow
 	clone := &models.Configuration{
 		UUID:          uuid.New().String(),
 		OwnerUsername: ownerUsername,
+		ProjectUUID:   resolvedProjectUUID,
 		Name:          newName,
 		Items:         original.Items,
 		TotalPrice:    &total,
@@ -304,6 +350,26 @@ func (s *ConfigurationService) CloneNoAuth(configUUID string, newName string, ow
 	return clone, nil
 }
 
+func (s *ConfigurationService) resolveProjectUUID(ownerUsername string, projectUUID *string) (*string, error) {
+	_ = ownerUsername
+	if s.projectRepo == nil {
+		return projectUUID, nil
+	}
+	if projectUUID == nil || *projectUUID == "" {
+		return nil, nil
+	}
+
+	project, err := s.projectRepo.GetByUUID(*projectUUID)
+	if err != nil {
+		return nil, ErrProjectNotFound
+	}
+	if !project.IsActive {
+		return nil, errors.New("project is archived")
+	}
+
+	return &project.UUID, nil
+}
+
 // RefreshPricesNoAuth refreshes prices without ownership check
 func (s *ConfigurationService) RefreshPricesNoAuth(uuid string) (*models.Configuration, error) {
 	config, err := s.configRepo.GetByUUID(uuid)

internal/services/local_configuration.go

@@ -55,6 +55,11 @@ func (s *LocalConfigurationService) Create(ownerUsername string, req *CreateConf
 		}
 	}
 
+	projectUUID, err := s.resolveProjectUUID(ownerUsername, req.ProjectUUID)
+	if err != nil {
+		return nil, err
+	}
+
 	total := req.Items.Total()
 	if req.ServerCount > 1 {
 		total *= float64(req.ServerCount)
@@ -63,6 +68,7 @@ func (s *LocalConfigurationService) Create(ownerUsername string, req *CreateConf
 	cfg := &models.Configuration{
 		UUID:          uuid.New().String(),
 		OwnerUsername: ownerUsername,
+		ProjectUUID:   projectUUID,
 		Name:          req.Name,
 		Items:         req.Items,
 		TotalPrice:    &total,
@@ -118,6 +124,11 @@ func (s *LocalConfigurationService) Update(uuid string, ownerUsername string, re
 		return nil, ErrConfigForbidden
 	}
 
+	projectUUID, err := s.resolveProjectUUID(ownerUsername, req.ProjectUUID)
+	if err != nil {
+		return nil, err
+	}
+
 	total := req.Items.Total()
 	if req.ServerCount > 1 {
 		total *= float64(req.ServerCount)
@@ -125,6 +136,7 @@ func (s *LocalConfigurationService) Update(uuid string, ownerUsername string, re
 
 	// Update fields
 	localCfg.Name = req.Name
+	localCfg.ProjectUUID = projectUUID
 	localCfg.Items = localdb.LocalConfigItems{}
 	for _, item := range req.Items {
 		localCfg.Items = append(localCfg.Items, localdb.LocalConfigItem{
@@ -210,10 +222,21 @@ func (s *LocalConfigurationService) Rename(uuid string, ownerUsername string, ne
 
 // Clone clones a configuration
 func (s *LocalConfigurationService) Clone(configUUID string, ownerUsername string, newName string) (*models.Configuration, error) {
+	return s.CloneToProject(configUUID, ownerUsername, newName, nil)
+}
+
+func (s *LocalConfigurationService) CloneToProject(configUUID string, ownerUsername string, newName string, projectUUID *string) (*models.Configuration, error) {
 	original, err := s.GetByUUID(configUUID, ownerUsername)
 	if err != nil {
 		return nil, err
 	}
+	resolvedProjectUUID := original.ProjectUUID
+	if projectUUID != nil {
+		resolvedProjectUUID, err = s.resolveProjectUUID(ownerUsername, projectUUID)
+		if err != nil {
+			return nil, err
+		}
+	}
 
 	total := original.Items.Total()
 	if original.ServerCount > 1 {
@@ -223,6 +246,7 @@ func (s *LocalConfigurationService) Clone(configUUID string, ownerUsername strin
 	clone := &models.Configuration{
 		UUID:          uuid.New().String(),
 		OwnerUsername: ownerUsername,
+		ProjectUUID:   resolvedProjectUUID,
 		Name:          newName,
 		Items:         original.Items,
 		TotalPrice:    &total,
@@ -362,12 +386,18 @@ func (s *LocalConfigurationService) UpdateNoAuth(uuid string, req *CreateConfigR
 		return nil, ErrConfigNotFound
 	}
 
+	projectUUID, err := s.resolveProjectUUID(localCfg.OriginalUsername, req.ProjectUUID)
+	if err != nil {
+		return nil, err
+	}
+
 	total := req.Items.Total()
 	if req.ServerCount > 1 {
 		total *= float64(req.ServerCount)
 	}
 
 	localCfg.Name = req.Name
+	localCfg.ProjectUUID = projectUUID
 	localCfg.Items = localdb.LocalConfigItems{}
 	for _, item := range req.Items {
 		localCfg.Items = append(localCfg.Items, localdb.LocalConfigItem{
@@ -440,10 +470,21 @@ func (s *LocalConfigurationService) RenameNoAuth(uuid string, newName string) (*
 
 // CloneNoAuth clones configuration without ownership check
 func (s *LocalConfigurationService) CloneNoAuth(configUUID string, newName string, ownerUsername string) (*models.Configuration, error) {
+	return s.CloneNoAuthToProject(configUUID, newName, ownerUsername, nil)
+}
+
+func (s *LocalConfigurationService) CloneNoAuthToProject(configUUID string, newName string, ownerUsername string, projectUUID *string) (*models.Configuration, error) {
 	original, err := s.GetByUUIDNoAuth(configUUID)
 	if err != nil {
 		return nil, err
 	}
+	resolvedProjectUUID := original.ProjectUUID
+	if projectUUID != nil {
+		resolvedProjectUUID, err = s.resolveProjectUUID(ownerUsername, projectUUID)
+		if err != nil {
+			return nil, err
+		}
+	}
 
 	total := original.Items.Total()
 	if original.ServerCount > 1 {
@@ -453,6 +494,7 @@ func (s *LocalConfigurationService) CloneNoAuth(configUUID string, newName strin
 	clone := &models.Configuration{
 		UUID:          uuid.New().String(),
 		OwnerUsername: ownerUsername,
+		ProjectUUID:   resolvedProjectUUID,
 		Name:          newName,
 		Items:         original.Items,
 		TotalPrice:    &total,
@@ -471,24 +513,59 @@ func (s *LocalConfigurationService) CloneNoAuth(configUUID string, newName strin
 	return clone, nil
 }
 
+// SetProjectNoAuth moves configuration to a different project without ownership check.
+func (s *LocalConfigurationService) SetProjectNoAuth(uuid string, projectUUID string) (*models.Configuration, error) {
+	localCfg, err := s.localDB.GetConfigurationByUUID(uuid)
+	if err != nil {
+		return nil, ErrConfigNotFound
+	}
+
+	var resolved *string
+	trimmed := strings.TrimSpace(projectUUID)
+	if trimmed == "" {
+		resolved, err = s.resolveProjectUUID(localCfg.OriginalUsername, &projectUUID)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		project, getErr := s.localDB.GetProjectByUUID(trimmed)
+		if getErr != nil {
+			return nil, ErrProjectNotFound
+		}
+		if !project.IsActive {
+			return nil, errors.New("project is archived")
+		}
+		resolved = &project.UUID
+	}
+
+	localCfg.ProjectUUID = resolved
+	localCfg.UpdatedAt = time.Now()
+	localCfg.SyncStatus = "pending"
+	return s.saveWithVersionAndPending(localCfg, "update", "")
+}
+
 // ListAll returns all configurations without user filter
 func (s *LocalConfigurationService) ListAll(page, perPage int) ([]models.Configuration, int64, error) {
-	return s.ListAllWithStatus(page, perPage, "active")
+	return s.ListAllWithStatus(page, perPage, "active", "")
 }
 
 // ListAllWithStatus returns configurations filtered by status: active|archived|all.
-func (s *LocalConfigurationService) ListAllWithStatus(page, perPage int, status string) ([]models.Configuration, int64, error) {
+func (s *LocalConfigurationService) ListAllWithStatus(page, perPage int, status string, search string) ([]models.Configuration, int64, error) {
 	localConfigs, err := s.localDB.GetConfigurations()
 	if err != nil {
 		return nil, 0, err
 	}
 
+	search = strings.ToLower(strings.TrimSpace(search))
 	configs := make([]models.Configuration, len(localConfigs))
 	configs = configs[:0]
 	for _, lc := range localConfigs {
 		if !matchesConfigStatus(lc.IsActive, status) {
 			continue
 		}
+		if search != "" && !strings.Contains(strings.ToLower(lc.Name), search) {
+			continue
+		}
 		configs = append(configs, *localdb.LocalToConfiguration(&lc))
 	}
 
@@ -960,6 +1037,7 @@ func (s *LocalConfigurationService) enqueueConfigurationPendingChangeTx(
 		EventID:           uuid.New().String(),
 		IdempotencyKey:    fmt.Sprintf("%s:v%d:%s", localCfg.UUID, version.VersionNo, operation),
 		ConfigurationUUID: localCfg.UUID,
+		ProjectUUID:       localCfg.ProjectUUID,
 		Operation:         operation,
 		CurrentVersionID:  version.ID,
 		CurrentVersionNo:  version.VersionNo,
@@ -1013,3 +1091,28 @@ func matchesConfigStatus(isActive bool, status string) bool {
 		return isActive
 	}
 }
+
+func (s *LocalConfigurationService) resolveProjectUUID(ownerUsername string, projectUUID *string) (*string, error) {
+	if ownerUsername == "" {
+		ownerUsername = s.localDB.GetDBUser()
+	}
+
+	if projectUUID == nil || strings.TrimSpace(*projectUUID) == "" {
+		project, err := s.localDB.EnsureDefaultProject(ownerUsername)
+		if err != nil {
+			return nil, err
+		}
+		return &project.UUID, nil
+	}
+
+	requested := strings.TrimSpace(*projectUUID)
+	project, err := s.localDB.GetProjectByUUID(requested)
+	if err != nil {
+		return nil, ErrProjectNotFound
+	}
+	if !project.IsActive {
+		return nil, errors.New("project is archived")
+	}
+
+	return &project.UUID, nil
+}

internal/services/project.go

@@ -0,0 +1,296 @@
+package services
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+	"time"
+
+	"git.mchus.pro/mchus/quoteforge/internal/localdb"
+	"git.mchus.pro/mchus/quoteforge/internal/models"
+	"git.mchus.pro/mchus/quoteforge/internal/services/sync"
+	"github.com/google/uuid"
+	"gorm.io/gorm"
+)
+
+var (
+	ErrProjectNotFound  = errors.New("project not found")
+	ErrProjectForbidden = errors.New("access to project forbidden")
+)
+
+type ProjectService struct {
+	localDB *localdb.LocalDB
+}
+
+func NewProjectService(localDB *localdb.LocalDB) *ProjectService {
+	return &ProjectService{localDB: localDB}
+}
+
+type CreateProjectRequest struct {
+	Name string `json:"name"`
+}
+
+type UpdateProjectRequest struct {
+	Name string `json:"name"`
+}
+
+type ProjectConfigurationsResult struct {
+	ProjectUUID string                 `json:"project_uuid"`
+	Configs     []models.Configuration `json:"configurations"`
+	Total       float64                `json:"total"`
+}
+
+func (s *ProjectService) Create(ownerUsername string, req *CreateProjectRequest) (*models.Project, error) {
+	name := strings.TrimSpace(req.Name)
+	if name == "" {
+		return nil, fmt.Errorf("project name is required")
+	}
+
+	now := time.Now()
+	localProject := &localdb.LocalProject{
+		UUID:          uuid.NewString(),
+		OwnerUsername: ownerUsername,
+		Name:          name,
+		IsActive:      true,
+		IsSystem:      false,
+		CreatedAt:     now,
+		UpdatedAt:     now,
+		SyncStatus:    "pending",
+	}
+	if err := s.localDB.SaveProject(localProject); err != nil {
+		return nil, err
+	}
+	if err := s.enqueueProjectPendingChange(localProject, "create"); err != nil {
+		return nil, err
+	}
+	return localdb.LocalToProject(localProject), nil
+}
+
+func (s *ProjectService) Update(projectUUID, ownerUsername string, req *UpdateProjectRequest) (*models.Project, error) {
+	localProject, err := s.localDB.GetProjectByUUID(projectUUID)
+	if err != nil {
+		return nil, ErrProjectNotFound
+	}
+	if localProject.OwnerUsername != ownerUsername {
+		return nil, ErrProjectForbidden
+	}
+
+	name := strings.TrimSpace(req.Name)
+	if name == "" {
+		return nil, fmt.Errorf("project name is required")
+	}
+
+	localProject.Name = name
+	localProject.UpdatedAt = time.Now()
+	localProject.SyncStatus = "pending"
+	if err := s.localDB.SaveProject(localProject); err != nil {
+		return nil, err
+	}
+	if err := s.enqueueProjectPendingChange(localProject, "update"); err != nil {
+		return nil, err
+	}
+	return localdb.LocalToProject(localProject), nil
+}
+
+func (s *ProjectService) Archive(projectUUID, ownerUsername string) error {
+	return s.setProjectActive(projectUUID, ownerUsername, false)
+}
+
+func (s *ProjectService) Reactivate(projectUUID, ownerUsername string) error {
+	return s.setProjectActive(projectUUID, ownerUsername, true)
+}
+
+func (s *ProjectService) setProjectActive(projectUUID, ownerUsername string, isActive bool) error {
+	return s.localDB.DB().Transaction(func(tx *gorm.DB) error {
+		var project localdb.LocalProject
+		if err := tx.Where("uuid = ?", projectUUID).First(&project).Error; err != nil {
+			return ErrProjectNotFound
+		}
+		if project.OwnerUsername != ownerUsername {
+			return ErrProjectForbidden
+		}
+		if project.IsActive == isActive {
+			return nil
+		}
+
+		project.IsActive = isActive
+		project.UpdatedAt = time.Now()
+		project.SyncStatus = "pending"
+		if err := tx.Save(&project).Error; err != nil {
+			return err
+		}
+
+		if err := s.enqueueProjectPendingChangeTx(tx, &project, boolToOp(isActive, "reactivate", "archive")); err != nil {
+			return err
+		}
+
+		var configs []localdb.LocalConfiguration
+		if err := tx.Where("project_uuid = ?", projectUUID).Find(&configs).Error; err != nil {
+			return err
+		}
+		for i := range configs {
+			cfg := configs[i]
+			cfg.IsActive = isActive
+			cfg.SyncStatus = "pending"
+			cfg.UpdatedAt = time.Now()
+			if err := tx.Save(&cfg).Error; err != nil {
+				return err
+			}
+
+			modelCfg := localdb.LocalToConfiguration(&cfg)
+			payload, err := json.Marshal(modelCfg)
+			if err != nil {
+				return err
+			}
+			change := &localdb.PendingChange{
+				EntityType: "configuration",
+				EntityUUID: cfg.UUID,
+				Operation:  "update",
+				Payload:    string(payload),
+				CreatedAt:  time.Now(),
+				Attempts:   0,
+			}
+			if err := tx.Create(change).Error; err != nil {
+				return err
+			}
+		}
+
+		return nil
+	})
+}
+
+func (s *ProjectService) ListByUser(ownerUsername string, includeArchived bool) ([]models.Project, error) {
+	localProjects, err := s.localDB.GetAllProjects(includeArchived)
+	if err != nil {
+		return nil, err
+	}
+
+	projects := make([]models.Project, 0, len(localProjects))
+	for i := range localProjects {
+		projects = append(projects, *localdb.LocalToProject(&localProjects[i]))
+	}
+	return projects, nil
+}
+
+func (s *ProjectService) GetByUUID(projectUUID, ownerUsername string) (*models.Project, error) {
+	localProject, err := s.localDB.GetProjectByUUID(projectUUID)
+	if err != nil {
+		return nil, ErrProjectNotFound
+	}
+	return localdb.LocalToProject(localProject), nil
+}
+
+func (s *ProjectService) ListConfigurations(projectUUID, ownerUsername, status string) (*ProjectConfigurationsResult, error) {
+	project, err := s.GetByUUID(projectUUID, ownerUsername)
+	if err != nil {
+		return nil, err
+	}
+	if !project.IsActive && status == "active" {
+		return &ProjectConfigurationsResult{
+			ProjectUUID: projectUUID,
+			Configs:     []models.Configuration{},
+			Total:       0,
+		}, nil
+	}
+
+	localConfigs, err := s.localDB.GetConfigurations()
+	if err != nil {
+		return nil, err
+	}
+
+	configs := make([]models.Configuration, 0, len(localConfigs))
+	total := 0.0
+	for i := range localConfigs {
+		localCfg := localConfigs[i]
+		if localCfg.ProjectUUID == nil || *localCfg.ProjectUUID != projectUUID {
+			continue
+		}
+		switch status {
+		case "active", "":
+			if !localCfg.IsActive {
+				continue
+			}
+		case "archived":
+			if localCfg.IsActive {
+				continue
+			}
+		case "all":
+		default:
+			if !localCfg.IsActive {
+				continue
+			}
+		}
+
+		cfg := localdb.LocalToConfiguration(&localCfg)
+		if cfg.TotalPrice != nil {
+			total += *cfg.TotalPrice
+		}
+		configs = append(configs, *cfg)
+	}
+
+	return &ProjectConfigurationsResult{
+		ProjectUUID: projectUUID,
+		Configs:     configs,
+		Total:       total,
+	}, nil
+}
+
+func (s *ProjectService) ResolveProjectUUID(ownerUsername string, projectUUID *string) (*string, error) {
+	if projectUUID == nil || strings.TrimSpace(*projectUUID) == "" {
+		project, err := s.localDB.EnsureDefaultProject(ownerUsername)
+		if err != nil {
+			return nil, err
+		}
+		return &project.UUID, nil
+	}
+
+	project, err := s.localDB.GetProjectByUUID(strings.TrimSpace(*projectUUID))
+	if err != nil {
+		return nil, ErrProjectNotFound
+	}
+	if project.OwnerUsername != ownerUsername {
+		return nil, ErrProjectForbidden
+	}
+	if !project.IsActive {
+		return nil, fmt.Errorf("project is archived")
+	}
+
+	resolved := project.UUID
+	return &resolved, nil
+}
+
+func (s *ProjectService) enqueueProjectPendingChange(project *localdb.LocalProject, operation string) error {
+	return s.enqueueProjectPendingChangeTx(s.localDB.DB(), project, operation)
+}
+
+func (s *ProjectService) enqueueProjectPendingChangeTx(tx *gorm.DB, project *localdb.LocalProject, operation string) error {
+	payload := sync.ProjectChangePayload{
+		EventID:        uuid.NewString(),
+		ProjectUUID:    project.UUID,
+		Operation:      operation,
+		Snapshot:       *localdb.LocalToProject(project),
+		CreatedAt:      time.Now().UTC(),
+		IdempotencyKey: fmt.Sprintf("%s:%d:%s", project.UUID, project.UpdatedAt.UnixNano(), operation),
+	}
+	raw, err := json.Marshal(payload)
+	if err != nil {
+		return err
+	}
+	change := &localdb.PendingChange{
+		EntityType: "project",
+		EntityUUID: project.UUID,
+		Operation:  operation,
+		Payload:    string(raw),
+		CreatedAt:  time.Now(),
+		Attempts:   0,
+	}
+	return tx.Create(change).Error
+}
+
+func boolToOp(v bool, whenTrue, whenFalse string) string {
+	if v {
+		return whenTrue
+	}
+	return whenFalse
+}

internal/services/sync/service.go

@@ -12,6 +12,7 @@ import (
 	"git.mchus.pro/mchus/quoteforge/internal/localdb"
 	"git.mchus.pro/mchus/quoteforge/internal/models"
 	"git.mchus.pro/mchus/quoteforge/internal/repository"
+	"github.com/google/uuid"
 	"gorm.io/gorm"
 )
 
@@ -19,8 +20,9 @@ var ErrOffline = errors.New("database is offline")
 
 // Service handles synchronization between MariaDB and local SQLite
 type Service struct {
-	connMgr *db.ConnectionManager
-	localDB *localdb.LocalDB
+	connMgr  *db.ConnectionManager
+	localDB  *localdb.LocalDB
+	directDB *gorm.DB
 }
 
 // NewService creates a new sync service
@@ -31,6 +33,14 @@ func NewService(connMgr *db.ConnectionManager, localDB *localdb.LocalDB) *Servic
 	}
 }
 
+// NewServiceWithDB creates sync service that uses a direct DB handle (used in tests).
+func NewServiceWithDB(mariaDB *gorm.DB, localDB *localdb.LocalDB) *Service {
+	return &Service{
+		localDB:  localDB,
+		directDB: mariaDB,
+	}
+}
+
 // SyncStatus represents the current sync status
 type SyncStatus struct {
 	LastSyncAt       *time.Time `json:"last_sync_at"`
@@ -52,6 +62,7 @@ type ConfigurationChangePayload struct {
 	EventID           string               `json:"event_id"`
 	IdempotencyKey    string               `json:"idempotency_key"`
 	ConfigurationUUID string               `json:"configuration_uuid"`
+	ProjectUUID       *string              `json:"project_uuid,omitempty"`
 	Operation         string               `json:"operation"` // create/update/rollback/deactivate/reactivate/delete
 	CurrentVersionID  string               `json:"current_version_id,omitempty"`
 	CurrentVersionNo  int                  `json:"current_version_no,omitempty"`
@@ -61,10 +72,19 @@ type ConfigurationChangePayload struct {
 	CreatedBy         *string              `json:"created_by,omitempty"`
 }
 
+type ProjectChangePayload struct {
+	EventID        string         `json:"event_id"`
+	IdempotencyKey string         `json:"idempotency_key"`
+	ProjectUUID    string         `json:"project_uuid"`
+	Operation      string         `json:"operation"`
+	Snapshot       models.Project `json:"snapshot"`
+	CreatedAt      time.Time      `json:"created_at"`
+}
+
 // ImportConfigurationsToLocal imports configurations from MariaDB into local SQLite.
 // Existing local configs with pending local changes are skipped to avoid data loss.
 func (s *Service) ImportConfigurationsToLocal() (*ConfigImportResult, error) {
-	mariaDB, err := s.connMgr.GetDB()
+	mariaDB, err := s.getDB()
 	if err != nil {
 		return nil, ErrOffline
 	}
@@ -130,9 +150,9 @@ func (s *Service) GetStatus() (*SyncStatus, error) {
 
 	// Count server pricelists (only if already connected, don't reconnect)
 	serverCount := 0
-	connStatus := s.connMgr.GetStatus()
+	connStatus := s.getConnectionStatus()
 	if connStatus.IsConnected {
-		if mariaDB, err := s.connMgr.GetDB(); err == nil && mariaDB != nil {
+		if mariaDB, err := s.getDB(); err == nil && mariaDB != nil {
 			pricelistRepo := repository.NewPricelistRepository(mariaDB)
 			activeCount, err := pricelistRepo.CountActive()
 			if err == nil {
@@ -170,13 +190,13 @@ func (s *Service) NeedSync() (bool, error) {
 	}
 
 	// Check if there are new pricelists on server (only if already connected)
-	connStatus := s.connMgr.GetStatus()
+	connStatus := s.getConnectionStatus()
 	if !connStatus.IsConnected {
 		// If offline, can't check server, no need to sync
 		return false, nil
 	}
 
-	mariaDB, err := s.connMgr.GetDB()
+	mariaDB, err := s.getDB()
 	if err != nil {
 		// If offline, can't check server, no need to sync
 		return false, nil
@@ -208,7 +228,7 @@ func (s *Service) SyncPricelists() (int, error) {
 	slog.Info("starting pricelist sync")
 
 	// Get database connection
-	mariaDB, err := s.connMgr.GetDB()
+	mariaDB, err := s.getDB()
 	if err != nil {
 		return 0, fmt.Errorf("database not available: %w", err)
 	}
@@ -301,7 +321,7 @@ func (s *Service) SyncPricelistItems(localPricelistID uint) (int, error) {
 	}
 
 	// Get database connection
-	mariaDB, err := s.connMgr.GetDB()
+	mariaDB, err := s.getDB()
 	if err != nil {
 		return 0, fmt.Errorf("database not available: %w", err)
 	}
@@ -418,8 +438,9 @@ func (s *Service) PushPendingChanges() (int, error) {
 	slog.Info("pushing pending changes", "count", len(changes))
 	pushed := 0
 	var syncedIDs []int64
+	sortedChanges := prioritizeProjectChanges(changes)
 
-	for _, change := range changes {
+	for _, change := range sortedChanges {
 		err := s.pushSingleChange(&change)
 		if err != nil {
 			slog.Warn("failed to push change", "id", change.ID, "type", change.EntityType, "operation", change.Operation, "error", err)
@@ -446,6 +467,8 @@ func (s *Service) PushPendingChanges() (int, error) {
 // pushSingleChange pushes a single pending change to the server
 func (s *Service) pushSingleChange(change *localdb.PendingChange) error {
 	switch change.EntityType {
+	case "project":
+		return s.pushProjectChange(change)
 	case "configuration":
 		return s.pushConfigurationChange(change)
 	default:
@@ -453,6 +476,95 @@ func (s *Service) pushSingleChange(change *localdb.PendingChange) error {
 	}
 }
 
+func prioritizeProjectChanges(changes []localdb.PendingChange) []localdb.PendingChange {
+	if len(changes) < 2 {
+		return changes
+	}
+
+	projectChanges := make([]localdb.PendingChange, 0, len(changes))
+	otherChanges := make([]localdb.PendingChange, 0, len(changes))
+	for _, change := range changes {
+		if change.EntityType == "project" {
+			projectChanges = append(projectChanges, change)
+			continue
+		}
+		otherChanges = append(otherChanges, change)
+	}
+
+	sorted := make([]localdb.PendingChange, 0, len(changes))
+	sorted = append(sorted, projectChanges...)
+	sorted = append(sorted, otherChanges...)
+	return sorted
+}
+
+func (s *Service) pushProjectChange(change *localdb.PendingChange) error {
+	payload, err := decodeProjectChangePayload(change)
+	if err != nil {
+		return fmt.Errorf("decode project payload: %w", err)
+	}
+
+	mariaDB, err := s.getDB()
+	if err != nil {
+		return fmt.Errorf("database not available: %w", err)
+	}
+
+	projectRepo := repository.NewProjectRepository(mariaDB)
+	project := payload.Snapshot
+	project.UUID = payload.ProjectUUID
+
+	serverProject, err := projectRepo.GetByUUID(project.UUID)
+	if err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			if createErr := projectRepo.Create(&project); createErr != nil {
+				return fmt.Errorf("create project on server: %w", createErr)
+			}
+		} else {
+			return fmt.Errorf("get project on server: %w", err)
+		}
+	} else {
+		project.ID = serverProject.ID
+		if updateErr := projectRepo.Update(&project); updateErr != nil {
+			return fmt.Errorf("update project on server: %w", updateErr)
+		}
+	}
+
+	localProject, localErr := s.localDB.GetProjectByUUID(project.UUID)
+	if localErr == nil {
+		if project.ID > 0 {
+			serverID := project.ID
+			localProject.ServerID = &serverID
+		}
+		localProject.SyncStatus = "synced"
+		now := time.Now()
+		localProject.SyncedAt = &now
+		_ = s.localDB.SaveProject(localProject)
+	}
+
+	return nil
+}
+
+func decodeProjectChangePayload(change *localdb.PendingChange) (ProjectChangePayload, error) {
+	var payload ProjectChangePayload
+	if err := json.Unmarshal([]byte(change.Payload), &payload); err == nil && payload.ProjectUUID != "" {
+		if payload.Operation == "" {
+			payload.Operation = change.Operation
+		}
+		return payload, nil
+	}
+
+	var project models.Project
+	if err := json.Unmarshal([]byte(change.Payload), &project); err != nil {
+		return ProjectChangePayload{}, fmt.Errorf("unmarshal legacy project payload: %w", err)
+	}
+
+	return ProjectChangePayload{
+		ProjectUUID:    project.UUID,
+		Operation:      change.Operation,
+		IdempotencyKey: fmt.Sprintf("%s:%s:legacy", project.UUID, change.Operation),
+		Snapshot:       project,
+	}, nil
+}
+
 // pushConfigurationChange pushes a configuration change to the server
 func (s *Service) pushConfigurationChange(change *localdb.PendingChange) error {
 	switch change.Operation {
@@ -485,7 +597,7 @@ func (s *Service) pushConfigurationCreate(change *localdb.PendingChange) error {
 	}
 
 	// Get database connection
-	mariaDB, err := s.connMgr.GetDB()
+	mariaDB, err := s.getDB()
 	if err != nil {
 		return fmt.Errorf("database not available: %w", err)
 	}
@@ -495,6 +607,9 @@ func (s *Service) pushConfigurationCreate(change *localdb.PendingChange) error {
 	if err := s.ensureConfigurationOwner(mariaDB, &cfg); err != nil {
 		return fmt.Errorf("resolve configuration owner: %w", err)
 	}
+	if err := s.ensureConfigurationProject(mariaDB, &cfg); err != nil {
+		return fmt.Errorf("resolve configuration project: %w", err)
+	}
 
 	// Create on server
 	if err := configRepo.Create(&cfg); err != nil {
@@ -540,7 +655,7 @@ func (s *Service) pushConfigurationUpdate(change *localdb.PendingChange) error {
 	}
 
 	// Get database connection
-	mariaDB, err := s.connMgr.GetDB()
+	mariaDB, err := s.getDB()
 	if err != nil {
 		return fmt.Errorf("database not available: %w", err)
 	}
@@ -550,6 +665,9 @@ func (s *Service) pushConfigurationUpdate(change *localdb.PendingChange) error {
 	if err := s.ensureConfigurationOwner(mariaDB, &cfg); err != nil {
 		return fmt.Errorf("resolve configuration owner: %w", err)
 	}
+	if err := s.ensureConfigurationProject(mariaDB, &cfg); err != nil {
+		return fmt.Errorf("resolve configuration project: %w", err)
+	}
 
 	// Ensure we have a server ID before updating
 	// If the payload doesn't have ID, get it from local configuration
@@ -620,6 +738,69 @@ func (s *Service) ensureConfigurationOwner(mariaDB *gorm.DB, cfg *models.Configu
 	return nil
 }
 
+func (s *Service) ensureConfigurationProject(mariaDB *gorm.DB, cfg *models.Configuration) error {
+	if cfg == nil {
+		return fmt.Errorf("configuration is nil")
+	}
+
+	projectRepo := repository.NewProjectRepository(mariaDB)
+
+	if cfg.ProjectUUID != nil && *cfg.ProjectUUID != "" {
+		_, err := projectRepo.GetByUUID(*cfg.ProjectUUID)
+		if err == nil {
+			return nil
+		}
+		if !errors.Is(err, gorm.ErrRecordNotFound) {
+			return err
+		}
+
+		localProject, localErr := s.localDB.GetProjectByUUID(*cfg.ProjectUUID)
+		if localErr != nil {
+			return err
+		}
+		modelProject := localdb.LocalToProject(localProject)
+		if modelProject.OwnerUsername == "" {
+			modelProject.OwnerUsername = cfg.OwnerUsername
+		}
+		if createErr := projectRepo.Create(modelProject); createErr != nil {
+			return createErr
+		}
+		if modelProject.ID > 0 {
+			serverID := modelProject.ID
+			localProject.ServerID = &serverID
+			localProject.SyncStatus = "synced"
+			now := time.Now()
+			localProject.SyncedAt = &now
+			_ = s.localDB.SaveProject(localProject)
+		}
+		return nil
+	}
+
+	systemProject := &models.Project{}
+	err := mariaDB.
+		Where("LOWER(TRIM(COALESCE(name, ''))) = LOWER(?) AND is_system = ?", "Без проекта", true).
+		Order("CASE WHEN TRIM(COALESCE(owner_username, '')) = '' THEN 0 ELSE 1 END, created_at ASC, id ASC").
+		First(systemProject).Error
+	if err != nil {
+		if !errors.Is(err, gorm.ErrRecordNotFound) {
+			return err
+		}
+		systemProject = &models.Project{
+			UUID:          uuid.NewString(),
+			OwnerUsername: "",
+			Name:          "Без проекта",
+			IsActive:      true,
+			IsSystem:      true,
+		}
+		if createErr := projectRepo.Create(systemProject); createErr != nil {
+			return createErr
+		}
+	}
+
+	cfg.ProjectUUID = &systemProject.UUID
+	return nil
+}
+
 func (s *Service) pushConfigurationRollback(change *localdb.PendingChange) error {
 	// Last-write-wins for now: rollback is pushed as an update with rollback metadata.
 	return s.pushConfigurationUpdate(change)
@@ -703,6 +884,7 @@ func decodeConfigurationChangePayload(change *localdb.PendingChange) (Configurat
 		EventID:           "",
 		IdempotencyKey:    fmt.Sprintf("%s:%s:legacy", cfg.UUID, change.Operation),
 		ConfigurationUUID: cfg.UUID,
+		ProjectUUID:       cfg.ProjectUUID,
 		Operation:         change.Operation,
 		ConflictPolicy:    "last_write_wins",
 		Snapshot:          cfg,
@@ -759,7 +941,7 @@ func (s *Service) loadCurrentConfigurationState(configurationUUID string) (model
 // pushConfigurationDelete deletes a configuration from the server
 func (s *Service) pushConfigurationDelete(change *localdb.PendingChange) error {
 	// Get database connection
-	mariaDB, err := s.connMgr.GetDB()
+	mariaDB, err := s.getDB()
 	if err != nil {
 		return fmt.Errorf("database not available: %w", err)
 	}
@@ -783,3 +965,23 @@ func (s *Service) pushConfigurationDelete(change *localdb.PendingChange) error {
 	slog.Info("configuration deleted on server", "uuid", change.EntityUUID)
 	return nil
 }
+
+func (s *Service) getDB() (*gorm.DB, error) {
+	if s.directDB != nil {
+		return s.directDB, nil
+	}
+	if s.connMgr == nil {
+		return nil, ErrOffline
+	}
+	return s.connMgr.GetDB()
+}
+
+func (s *Service) getConnectionStatus() db.ConnectionStatus {
+	if s.directDB != nil {
+		return db.ConnectionStatus{IsConnected: true}
+	}
+	if s.connMgr == nil {
+		return db.ConnectionStatus{IsConnected: false}
+	}
+	return s.connMgr.GetStatus()
+}

internal/services/sync/service_order_test.go

@@ -0,0 +1,25 @@
+package sync
+
+import (
+	"testing"
+
+	"git.mchus.pro/mchus/quoteforge/internal/localdb"
+)
+
+func TestPrioritizeProjectChanges(t *testing.T) {
+	changes := []localdb.PendingChange{
+		{ID: 1, EntityType: "configuration"},
+		{ID: 2, EntityType: "project"},
+		{ID: 3, EntityType: "configuration"},
+		{ID: 4, EntityType: "project"},
+	}
+
+	sorted := prioritizeProjectChanges(changes)
+	if len(sorted) != 4 {
+		t.Fatalf("unexpected sorted length: %d", len(sorted))
+	}
+
+	if sorted[0].EntityType != "project" || sorted[1].EntityType != "project" {
+		t.Fatalf("expected project changes first, got order: %s, %s", sorted[0].EntityType, sorted[1].EntityType)
+	}
+}

internal/services/sync/service_projects_push_test.go

@@ -0,0 +1,273 @@
+package sync_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"git.mchus.pro/mchus/quoteforge/internal/localdb"
+	"git.mchus.pro/mchus/quoteforge/internal/models"
+	"git.mchus.pro/mchus/quoteforge/internal/services"
+	syncsvc "git.mchus.pro/mchus/quoteforge/internal/services/sync"
+	"github.com/glebarez/sqlite"
+	"gorm.io/gorm"
+)
+
+func TestPushPendingChangesProjectsBeforeConfigurations(t *testing.T) {
+	local := newLocalDBForSyncTest(t)
+	serverDB := newServerDBForSyncTest(t)
+
+	localSync := syncsvc.NewService(nil, local)
+	projectService := services.NewProjectService(local)
+	configService := services.NewLocalConfigurationService(local, localSync, &services.QuoteService{}, func() bool { return false })
+
+	project, err := projectService.Create("tester", &services.CreateProjectRequest{Name: "Project A"})
+	if err != nil {
+		t.Fatalf("create project: %v", err)
+	}
+
+	cfg, err := configService.Create("tester", &services.CreateConfigRequest{
+		Name:        "Cfg A",
+		Items:       models.ConfigItems{{LotName: "CPU_A", Quantity: 1, UnitPrice: 1000}},
+		ServerCount: 1,
+		ProjectUUID: &project.UUID,
+	})
+	if err != nil {
+		t.Fatalf("create config: %v", err)
+	}
+
+	pushService := syncsvc.NewServiceWithDB(serverDB, local)
+	pushed, err := pushService.PushPendingChanges()
+	if err != nil {
+		t.Fatalf("push pending changes: %v", err)
+	}
+	if pushed < 2 {
+		t.Fatalf("expected at least 2 pushed changes, got %d", pushed)
+	}
+
+	var serverProject models.Project
+	if err := serverDB.Where("uuid = ?", project.UUID).First(&serverProject).Error; err != nil {
+		t.Fatalf("project not pushed to server: %v", err)
+	}
+
+	var serverCfg models.Configuration
+	if err := serverDB.Where("uuid = ?", cfg.UUID).First(&serverCfg).Error; err != nil {
+		t.Fatalf("configuration not pushed to server: %v", err)
+	}
+	if serverCfg.ProjectUUID == nil || *serverCfg.ProjectUUID != project.UUID {
+		t.Fatalf("expected project_uuid=%s on pushed config, got %v", project.UUID, serverCfg.ProjectUUID)
+	}
+
+	if got := local.CountPendingChanges(); got != 0 {
+		t.Fatalf("expected pending queue to be empty, got %d", got)
+	}
+}
+
+func TestPushPendingChangesSkipsStaleUpdateAndAppliesLatest(t *testing.T) {
+	local := newLocalDBForSyncTest(t)
+	serverDB := newServerDBForSyncTest(t)
+
+	localSync := syncsvc.NewService(nil, local)
+	configService := services.NewLocalConfigurationService(local, localSync, &services.QuoteService{}, func() bool { return false })
+	pushService := syncsvc.NewServiceWithDB(serverDB, local)
+
+	created, err := configService.Create("tester", &services.CreateConfigRequest{
+		Name:        "Cfg v1",
+		Items:       models.ConfigItems{{LotName: "CPU_A", Quantity: 1, UnitPrice: 1000}},
+		ServerCount: 1,
+	})
+	if err != nil {
+		t.Fatalf("create config: %v", err)
+	}
+	if _, err := pushService.PushPendingChanges(); err != nil {
+		t.Fatalf("initial push: %v", err)
+	}
+
+	if _, err := configService.UpdateNoAuth(created.UUID, &services.CreateConfigRequest{
+		Name:        "Cfg v2",
+		Items:       models.ConfigItems{{LotName: "CPU_A", Quantity: 2, UnitPrice: 1000}},
+		ServerCount: 1,
+		ProjectUUID: created.ProjectUUID,
+	}); err != nil {
+		t.Fatalf("update config: %v", err)
+	}
+
+	localCfg, err := local.GetConfigurationByUUID(created.UUID)
+	if err != nil {
+		t.Fatalf("get local config: %v", err)
+	}
+	cfgSnapshot := localdb.LocalToConfiguration(localCfg)
+	stalePayload := syncsvc.ConfigurationChangePayload{
+		EventID:           "stale-event",
+		IdempotencyKey:    fmt.Sprintf("%s:v1:update", created.UUID),
+		ConfigurationUUID: created.UUID,
+		ProjectUUID:       cfgSnapshot.ProjectUUID,
+		Operation:         "update",
+		CurrentVersionID:  "stale-v1",
+		CurrentVersionNo:  1,
+		ConflictPolicy:    "last_write_wins",
+		Snapshot:          *cfgSnapshot,
+		CreatedAt:         time.Now().UTC().Add(-2 * time.Second),
+	}
+	raw, err := json.Marshal(stalePayload)
+	if err != nil {
+		t.Fatalf("marshal stale payload: %v", err)
+	}
+	if err := local.DB().Create(&localdb.PendingChange{
+		EntityType: "configuration",
+		EntityUUID: created.UUID,
+		Operation:  "update",
+		Payload:    string(raw),
+		CreatedAt:  time.Now().Add(-1 * time.Second),
+	}).Error; err != nil {
+		t.Fatalf("insert stale pending change: %v", err)
+	}
+
+	if _, err := pushService.PushPendingChanges(); err != nil {
+		t.Fatalf("push pending with stale event: %v", err)
+	}
+
+	var serverCfg models.Configuration
+	if err := serverDB.Where("uuid = ?", created.UUID).First(&serverCfg).Error; err != nil {
+		t.Fatalf("get server config: %v", err)
+	}
+	if serverCfg.Name != "Cfg v2" {
+		t.Fatalf("expected latest name to win, got %q", serverCfg.Name)
+	}
+	if got := local.CountPendingChanges(); got != 0 {
+		t.Fatalf("expected empty pending queue, got %d", got)
+	}
+}
+
+func TestPushPendingChangesCreateIsIdempotent(t *testing.T) {
+	local := newLocalDBForSyncTest(t)
+	serverDB := newServerDBForSyncTest(t)
+
+	localSync := syncsvc.NewService(nil, local)
+	configService := services.NewLocalConfigurationService(local, localSync, &services.QuoteService{}, func() bool { return false })
+	pushService := syncsvc.NewServiceWithDB(serverDB, local)
+
+	created, err := configService.Create("tester", &services.CreateConfigRequest{
+		Name:        "Cfg Idempotent",
+		Items:       models.ConfigItems{{LotName: "CPU_B", Quantity: 1, UnitPrice: 500}},
+		ServerCount: 1,
+	})
+	if err != nil {
+		t.Fatalf("create config: %v", err)
+	}
+	if _, err := pushService.PushPendingChanges(); err != nil {
+		t.Fatalf("initial push: %v", err)
+	}
+
+	localCfg, err := local.GetConfigurationByUUID(created.UUID)
+	if err != nil {
+		t.Fatalf("get local config: %v", err)
+	}
+	currentVersionNo, currentVersionID := getCurrentVersionInfo(t, local, created.UUID, localCfg.CurrentVersionID)
+	cfgSnapshot := localdb.LocalToConfiguration(localCfg)
+	duplicatePayload := syncsvc.ConfigurationChangePayload{
+		EventID:           "duplicate-create-event",
+		IdempotencyKey:    fmt.Sprintf("%s:v%d:create", created.UUID, currentVersionNo),
+		ConfigurationUUID: created.UUID,
+		ProjectUUID:       cfgSnapshot.ProjectUUID,
+		Operation:         "create",
+		CurrentVersionID:  currentVersionID,
+		CurrentVersionNo:  currentVersionNo,
+		ConflictPolicy:    "last_write_wins",
+		Snapshot:          *cfgSnapshot,
+		CreatedAt:         time.Now().UTC(),
+	}
+	raw, err := json.Marshal(duplicatePayload)
+	if err != nil {
+		t.Fatalf("marshal duplicate payload: %v", err)
+	}
+	if err := local.AddPendingChange("configuration", created.UUID, "create", string(raw)); err != nil {
+		t.Fatalf("add duplicate create pending change: %v", err)
+	}
+
+	if pushed, err := pushService.PushPendingChanges(); err != nil {
+		t.Fatalf("push duplicate create: %v", err)
+	} else if pushed != 1 {
+		t.Fatalf("expected 1 pushed change for duplicate create, got %d", pushed)
+	}
+
+	var count int64
+	if err := serverDB.Model(&models.Configuration{}).Where("uuid = ?", created.UUID).Count(&count).Error; err != nil {
+		t.Fatalf("count server configs: %v", err)
+	}
+	if count != 1 {
+		t.Fatalf("expected one server row after idempotent create, got %d", count)
+	}
+}
+
+func newLocalDBForSyncTest(t *testing.T) *localdb.LocalDB {
+	t.Helper()
+	localPath := filepath.Join(t.TempDir(), "local.db")
+	local, err := localdb.New(localPath)
+	if err != nil {
+		t.Fatalf("init local db: %v", err)
+	}
+	t.Cleanup(func() { _ = local.Close() })
+	return local
+}
+
+func newServerDBForSyncTest(t *testing.T) *gorm.DB {
+	t.Helper()
+	serverPath := filepath.Join(t.TempDir(), "server.db")
+	db, err := gorm.Open(sqlite.Open(serverPath), &gorm.Config{})
+	if err != nil {
+		t.Fatalf("open server sqlite: %v", err)
+	}
+	if err := db.Exec(`
+CREATE TABLE qt_projects (
+	id INTEGER PRIMARY KEY AUTOINCREMENT,
+	uuid TEXT NOT NULL UNIQUE,
+	owner_username TEXT NOT NULL,
+	name TEXT NOT NULL,
+	is_active INTEGER NOT NULL DEFAULT 1,
+	is_system INTEGER NOT NULL DEFAULT 0,
+	created_at DATETIME,
+	updated_at DATETIME
+);`).Error; err != nil {
+		t.Fatalf("create qt_projects: %v", err)
+	}
+	if err := db.Exec(`
+CREATE TABLE qt_configurations (
+	id INTEGER PRIMARY KEY AUTOINCREMENT,
+	uuid TEXT NOT NULL UNIQUE,
+	user_id INTEGER NULL,
+	owner_username TEXT NOT NULL,
+	project_uuid TEXT NULL,
+	app_version TEXT NULL,
+	name TEXT NOT NULL,
+	items TEXT NOT NULL,
+	total_price REAL NULL,
+	custom_price REAL NULL,
+	notes TEXT NULL,
+	is_template INTEGER NOT NULL DEFAULT 0,
+	server_count INTEGER NOT NULL DEFAULT 1,
+	price_updated_at DATETIME NULL,
+	created_at DATETIME
+);`).Error; err != nil {
+		t.Fatalf("create qt_configurations: %v", err)
+	}
+	return db
+}
+
+func getCurrentVersionInfo(t *testing.T, local *localdb.LocalDB, configurationUUID string, currentVersionID *string) (int, string) {
+	t.Helper()
+	if currentVersionID == nil || *currentVersionID == "" {
+		t.Fatalf("current version id is empty for %s", configurationUUID)
+	}
+
+	var version localdb.LocalConfigurationVersion
+	if err := local.DB().
+		Where("id = ? AND configuration_uuid = ?", *currentVersionID, configurationUUID).
+		First(&version).Error; err != nil {
+		t.Fatalf("get current version info: %v", err)
+	}
+
+	return version.VersionNo, version.ID
+}