feat: initialize default root user

backend/cmd/api/main.go

@@ -5,6 +5,7 @@ import (
 
 	"senlinai-agent/backend/internal/config"
 	"senlinai-agent/backend/internal/httpx"
+	"senlinai-agent/backend/internal/initdb"
 	"senlinai-agent/backend/internal/logic/ai"
 	"senlinai-agent/backend/internal/logic/auth"
 	"senlinai-agent/backend/internal/logic/files"
@@ -22,6 +23,9 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
+	if err := initdb.InitUser(models.DBService); err != nil {
+		log.Fatal(err)
+	}
 
 	authService := auth.NewService(cfg.AuthSecret)
 	projectService := projects.NewService()

backend/internal/initdb/user.go

@@ -0,0 +1,36 @@
+package initdb
+
+import (
+	"golang.org/x/crypto/bcrypt"
+	"gorm.io/gorm"
+	"senlinai-agent/backend/internal/models"
+)
+
+const (
+	rootUsername = "root"
+	rootPassword = "123456"
+	rootRole     = "root"
+)
+
+// InitUser creates the default root account when the user table is empty.
+func InitUser(database *gorm.DB) error {
+	var count int64
+	if err := database.Model(&models.SenlinAgentUser{}).Count(&count).Error; err != nil {
+		return err
+	}
+	if count > 0 {
+		return nil
+	}
+
+	passwordHash, err := bcrypt.GenerateFromPassword([]byte(rootPassword), bcrypt.DefaultCost)
+	if err != nil {
+		return err
+	}
+
+	return database.Create(&models.SenlinAgentUser{
+		Email:        rootUsername,
+		DisplayName:  rootUsername,
+		PasswordHash: string(passwordHash),
+		Role:         rootRole,
+	}).Error
+}

backend/internal/initdb/user_test.go

@@ -0,0 +1,52 @@
+package initdb
+
+import (
+	"testing"
+
+	"github.com/glebarez/sqlite"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/crypto/bcrypt"
+	"gorm.io/gorm"
+	"senlinai-agent/backend/internal/models"
+)
+
+func TestInitUserCreatesRootUserWhenTableIsEmpty(t *testing.T) {
+	database := newUserTestDatabase(t)
+
+	require.NoError(t, InitUser(database))
+
+	var users []models.SenlinAgentUser
+	require.NoError(t, database.Find(&users).Error)
+	require.Len(t, users, 1)
+	require.Equal(t, rootUsername, users[0].Email)
+	require.Equal(t, rootUsername, users[0].DisplayName)
+	require.Equal(t, rootRole, users[0].Role)
+	require.NoError(t, bcrypt.CompareHashAndPassword([]byte(users[0].PasswordHash), []byte(rootPassword)))
+}
+
+func TestInitUserDoesNothingWhenTableIsNotEmpty(t *testing.T) {
+	database := newUserTestDatabase(t)
+	existing := models.SenlinAgentUser{
+		Email:        "existing@example.com",
+		DisplayName:  "Existing User",
+		PasswordHash: "existing-hash",
+		Role:         "user",
+	}
+	require.NoError(t, database.Create(&existing).Error)
+
+	require.NoError(t, InitUser(database))
+
+	var users []models.SenlinAgentUser
+	require.NoError(t, database.Find(&users).Error)
+	require.Len(t, users, 1)
+	require.Equal(t, existing.Email, users[0].Email)
+}
+
+func newUserTestDatabase(t *testing.T) *gorm.DB {
+	t.Helper()
+
+	database, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{})
+	require.NoError(t, err)
+	require.NoError(t, database.AutoMigrate(&models.SenlinAgentUser{}))
+	return database
+}