feat(backend): add user custom attributes system

Add a flexible user attribute system that allows admins to define
custom fields for users (text, textarea, number, email, url, date,
select, multi_select types).

- Add Ent schemas for UserAttributeDefinition and UserAttributeValue
- Add service layer with validation logic
- Add repository layer with batch operations support
- Add admin API endpoints for CRUD and reorder operations
- Add batch API for loading attribute values for multiple users
- Add database migration (018_user_attributes.sql)

🤖 Generated with [Claude Code](https://claude.com/claude-code

)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/ent/userattributevalue/userattributevalue.go

+// Code generated by ent, DO NOT EDIT.
+
+package userattributevalue
+
+import (
+	"time"
+
+	"entgo.io/ent/dialect/sql"
+	"entgo.io/ent/dialect/sql/sqlgraph"
+)
+
+const (
+	// Label holds the string label denoting the userattributevalue type in the database.
+	Label = "user_attribute_value"
+	// FieldID holds the string denoting the id field in the database.
+	FieldID = "id"
+	// FieldCreatedAt holds the string denoting the created_at field in the database.
+	FieldCreatedAt = "created_at"
+	// FieldUpdatedAt holds the string denoting the updated_at field in the database.
+	FieldUpdatedAt = "updated_at"
+	// FieldUserID holds the string denoting the user_id field in the database.
+	FieldUserID = "user_id"
+	// FieldAttributeID holds the string denoting the attribute_id field in the database.
+	FieldAttributeID = "attribute_id"
+	// FieldValue holds the string denoting the value field in the database.
+	FieldValue = "value"
+	// EdgeUser holds the string denoting the user edge name in mutations.
+	EdgeUser = "user"
+	// EdgeDefinition holds the string denoting the definition edge name in mutations.
+	EdgeDefinition = "definition"
+	// Table holds the table name of the userattributevalue in the database.
+	Table = "user_attribute_values"
+	// UserTable is the table that holds the user relation/edge.
+	UserTable = "user_attribute_values"
+	// UserInverseTable is the table name for the User entity.
+	// It exists in this package in order to avoid circular dependency with the "user" package.
+	UserInverseTable = "users"
+	// UserColumn is the table column denoting the user relation/edge.
+	UserColumn = "user_id"
+	// DefinitionTable is the table that holds the definition relation/edge.
+	DefinitionTable = "user_attribute_values"
+	// DefinitionInverseTable is the table name for the UserAttributeDefinition entity.
+	// It exists in this package in order to avoid circular dependency with the "userattributedefinition" package.
+	DefinitionInverseTable = "user_attribute_definitions"
+	// DefinitionColumn is the table column denoting the definition relation/edge.
+	DefinitionColumn = "attribute_id"
+)
+
+// Columns holds all SQL columns for userattributevalue fields.
+var Columns = []string{
+	FieldID,
+	FieldCreatedAt,
+	FieldUpdatedAt,
+	FieldUserID,
+	FieldAttributeID,
+	FieldValue,
+}
+
+// ValidColumn reports if the column name is valid (part of the table columns).
+func ValidColumn(column string) bool {
+	for i := range Columns {
+		if column == Columns[i] {
+			return true
+		}
+	}
+	return false
+}
+
+var (
+	// DefaultCreatedAt holds the default value on creation for the "created_at" field.
+	DefaultCreatedAt func() time.Time
+	// DefaultUpdatedAt holds the default value on creation for the "updated_at" field.
+	DefaultUpdatedAt func() time.Time
+	// UpdateDefaultUpdatedAt holds the default value on update for the "updated_at" field.
+	UpdateDefaultUpdatedAt func() time.Time
+	// DefaultValue holds the default value on creation for the "value" field.
+	DefaultValue string
+)
+
+// OrderOption defines the ordering options for the UserAttributeValue queries.
+type OrderOption func(*sql.Selector)
+
+// ByID orders the results by the id field.
+func ByID(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldID, opts...).ToFunc()
+}
+
+// ByCreatedAt orders the results by the created_at field.
+func ByCreatedAt(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldCreatedAt, opts...).ToFunc()
+}
+
+// ByUpdatedAt orders the results by the updated_at field.
+func ByUpdatedAt(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldUpdatedAt, opts...).ToFunc()
+}
+
+// ByUserID orders the results by the user_id field.
+func ByUserID(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldUserID, opts...).ToFunc()
+}
+
+// ByAttributeID orders the results by the attribute_id field.
+func ByAttributeID(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldAttributeID, opts...).ToFunc()
+}
+
+// ByValue orders the results by the value field.
+func ByValue(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldValue, opts...).ToFunc()
+}
+
+// ByUserField orders the results by user field.
+func ByUserField(field string, opts ...sql.OrderTermOption) OrderOption {
+	return func(s *sql.Selector) {
+		sqlgraph.OrderByNeighborTerms(s, newUserStep(), sql.OrderByField(field, opts...))
+	}
+}
+
+// ByDefinitionField orders the results by definition field.
+func ByDefinitionField(field string, opts ...sql.OrderTermOption) OrderOption {
+	return func(s *sql.Selector) {
+		sqlgraph.OrderByNeighborTerms(s, newDefinitionStep(), sql.OrderByField(field, opts...))
+	}
+}
+func newUserStep() *sqlgraph.Step {
+	return sqlgraph.NewStep(
+		sqlgraph.From(Table, FieldID),
+		sqlgraph.To(UserInverseTable, FieldID),
+		sqlgraph.Edge(sqlgraph.M2O, true, UserTable, UserColumn),
+	)
+}
+func newDefinitionStep() *sqlgraph.Step {
+	return sqlgraph.NewStep(
+		sqlgraph.From(Table, FieldID),
+		sqlgraph.To(DefinitionInverseTable, FieldID),
+		sqlgraph.Edge(sqlgraph.M2O, true, DefinitionTable, DefinitionColumn),
+	)
+}

backend/ent/userattributevalue_delete.go

+// Code generated by ent, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+
+	"entgo.io/ent/dialect/sql"
+	"entgo.io/ent/dialect/sql/sqlgraph"
+	"entgo.io/ent/schema/field"
+	"github.com/Wei-Shaw/sub2api/ent/predicate"
+	"github.com/Wei-Shaw/sub2api/ent/userattributevalue"
+)
+
+// UserAttributeValueDelete is the builder for deleting a UserAttributeValue entity.
+type UserAttributeValueDelete struct {
+	config
+	hooks    []Hook
+	mutation *UserAttributeValueMutation
+}
+
+// Where appends a list predicates to the UserAttributeValueDelete builder.
+func (_d *UserAttributeValueDelete) Where(ps ...predicate.UserAttributeValue) *UserAttributeValueDelete {
+	_d.mutation.Where(ps...)
+	return _d
+}
+
+// Exec executes the deletion query and returns how many vertices were deleted.
+func (_d *UserAttributeValueDelete) Exec(ctx context.Context) (int, error) {
+	return withHooks(ctx, _d.sqlExec, _d.mutation, _d.hooks)
+}
+
+// ExecX is like Exec, but panics if an error occurs.
+func (_d *UserAttributeValueDelete) ExecX(ctx context.Context) int {
+	n, err := _d.Exec(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return n
+}
+
+func (_d *UserAttributeValueDelete) sqlExec(ctx context.Context) (int, error) {
+	_spec := sqlgraph.NewDeleteSpec(userattributevalue.Table, sqlgraph.NewFieldSpec(userattributevalue.FieldID, field.TypeInt64))
+	if ps := _d.mutation.predicates; len(ps) > 0 {
+		_spec.Predicate = func(selector *sql.Selector) {
+			for i := range ps {
+				ps[i](selector)
+			}
+		}
+	}
+	affected, err := sqlgraph.DeleteNodes(ctx, _d.driver, _spec)
+	if err != nil && sqlgraph.IsConstraintError(err) {
+		err = &ConstraintError{msg: err.Error(), wrap: err}
+	}
+	_d.mutation.done = true
+	return affected, err
+}
+
+// UserAttributeValueDeleteOne is the builder for deleting a single UserAttributeValue entity.
+type UserAttributeValueDeleteOne struct {
+	_d *UserAttributeValueDelete
+}
+
+// Where appends a list predicates to the UserAttributeValueDelete builder.
+func (_d *UserAttributeValueDeleteOne) Where(ps ...predicate.UserAttributeValue) *UserAttributeValueDeleteOne {
+	_d._d.mutation.Where(ps...)
+	return _d
+}
+
+// Exec executes the deletion query.
+func (_d *UserAttributeValueDeleteOne) Exec(ctx context.Context) error {
+	n, err := _d._d.Exec(ctx)
+	switch {
+	case err != nil:
+		return err
+	case n == 0:
+		return &NotFoundError{userattributevalue.Label}
+	default:
+		return nil
+	}
+}
+
+// ExecX is like Exec, but panics if an error occurs.
+func (_d *UserAttributeValueDeleteOne) ExecX(ctx context.Context) {
+	if err := _d.Exec(ctx); err != nil {
+		panic(err)
+	}
+}

backend/internal/handler/handler.go

@@ -20,6 +20,7 @@ type AdminHandlers struct {
 	System           *admin.SystemHandler
 	Subscription     *admin.SubscriptionHandler
 	Usage            *admin.UsageHandler
+	UserAttribute    *admin.UserAttributeHandler
 }
 
 // Handlers contains all HTTP handlers

backend/internal/handler/wire.go

@@ -23,6 +23,7 @@ func ProvideAdminHandlers(
 	systemHandler *admin.SystemHandler,
 	subscriptionHandler *admin.SubscriptionHandler,
 	usageHandler *admin.UsageHandler,
+	userAttributeHandler *admin.UserAttributeHandler,
 ) *AdminHandlers {
 	return &AdminHandlers{
 		Dashboard:        dashboardHandler,
@@ -39,6 +40,7 @@ func ProvideAdminHandlers(
 		System:           systemHandler,
 		Subscription:     subscriptionHandler,
 		Usage:            usageHandler,
+		UserAttribute:    userAttributeHandler,
 	}
 }
 
@@ -107,6 +109,7 @@ var ProviderSet = wire.NewSet(
 	ProvideSystemHandler,
 	admin.NewSubscriptionHandler,
 	admin.NewUsageHandler,
+	admin.NewUserAttributeHandler,
 
 	// AdminHandlers and Handlers constructors
 	ProvideAdminHandlers,

backend/internal/repository/wire.go

@@ -36,6 +36,8 @@ var ProviderSet = wire.NewSet(
 	NewUsageLogRepository,
 	NewSettingRepository,
 	NewUserSubscriptionRepository,
+	NewUserAttributeDefinitionRepository,
+	NewUserAttributeValueRepository,
 
 	// Cache implementations
 	NewGatewayCache,

backend/internal/server/routes/admin.go

@@ -54,6 +54,9 @@ func RegisterAdminRoutes(
 
 		// 使用记录管理
 		registerUsageRoutes(admin, h)
+
+		// 用户属性管理
+		registerUserAttributeRoutes(admin, h)
 	}
 }
 
@@ -82,6 +85,10 @@ func registerUserManagementRoutes(admin *gin.RouterGroup, h *handler.Handlers) {
 		users.POST("/:id/balance", h.Admin.User.UpdateBalance)
 		users.GET("/:id/api-keys", h.Admin.User.GetUserAPIKeys)
 		users.GET("/:id/usage", h.Admin.User.GetUserUsage)
+
+		// User attribute values
+		users.GET("/:id/attributes", h.Admin.UserAttribute.GetUserAttributes)
+		users.PUT("/:id/attributes", h.Admin.UserAttribute.UpdateUserAttributes)
 	}
 }
 
@@ -242,3 +249,15 @@ func registerUsageRoutes(admin *gin.RouterGroup, h *handler.Handlers) {
 		usage.GET("/search-api-keys", h.Admin.Usage.SearchApiKeys)
 	}
 }
+
+func registerUserAttributeRoutes(admin *gin.RouterGroup, h *handler.Handlers) {
+	attrs := admin.Group("/user-attributes")
+	{
+		attrs.GET("", h.Admin.UserAttribute.ListDefinitions)
+		attrs.POST("", h.Admin.UserAttribute.CreateDefinition)
+		attrs.POST("/batch", h.Admin.UserAttribute.GetBatchUserAttributes)
+		attrs.PUT("/reorder", h.Admin.UserAttribute.ReorderDefinitions)
+		attrs.PUT("/:id", h.Admin.UserAttribute.UpdateDefinition)
+		attrs.DELETE("/:id", h.Admin.UserAttribute.DeleteDefinition)
+	}
+}

backend/internal/service/wire.go

@@ -125,4 +125,5 @@ var ProviderSet = wire.NewSet(
 	ProvideTimingWheelService,
 	ProvideDeferredService,
 	ProvideAntigravityQuotaRefresher,
+	NewUserAttributeService,
 )