fix: serialize concurrent demo seeding

backend/internal/seed/demo_test.go

@@ -2,10 +2,13 @@ package seed
 
 import (
 	"fmt"
+	"sync/atomic"
 	"testing"
+	"time"
 
 	"github.com/glebarez/sqlite"
 	"github.com/stretchr/testify/require"
+	"golang.org/x/crypto/bcrypt"
 	"gorm.io/gorm"
 	"gorm.io/gorm/logger"
 	"senlinai-agent/backend/internal/logic/auth"
@@ -87,6 +90,7 @@ func TestDemoSeedUsesIdentifierAsStableProjectKey(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, original.ID, second.Projects[0].ID)
 	require.Equal(t, "A1", second.Projects[0].Identifier)
+	require.Equal(t, "本地重命名项目", second.Projects[0].Name)
 	var projectCount int64
 	require.NoError(t, database.Model(&models.SenlinAgentProject{}).
 		Where("owner_id = ? AND identifier = ?", first.User.ID, "A1").
@@ -94,6 +98,77 @@ func TestDemoSeedUsesIdentifierAsStableProjectKey(t *testing.T) {
 	require.Equal(t, int64(1), projectCount)
 }
 
+func TestDemoSeedAcceptsAConcurrentWinnerWithoutOverwritingUser(t *testing.T) {
+	database := newTestDB(t)
+	const email = "seed-race@senlin.ai"
+	winnerHash, err := bcrypt.GenerateFromPassword([]byte("winner-password"), bcrypt.MinCost)
+	require.NoError(t, err)
+
+	var injected atomic.Bool
+	callbackName := "test:inject_concurrent_seed_user"
+	require.NoError(t, database.Callback().Create().Before("gorm:create").Register(callbackName, func(tx *gorm.DB) {
+		if tx.Statement.Schema == nil || tx.Statement.Schema.Table != (models.SenlinAgentUser{}).TableName() {
+			return
+		}
+		if !injected.CompareAndSwap(false, true) {
+			return
+		}
+		now := time.Now().UTC()
+		tx.AddError(tx.Exec(
+			"INSERT INTO senlin_agent_users (identity, email, display_name, password_hash, role, created_at, updated_at) VALUES (?, ?, ?, ?, ?, ?, ?)",
+			"00000000-0000-7000-8000-000000000001", email, "并发胜出用户", string(winnerHash), "user", now, now,
+		).Error)
+	}))
+	t.Cleanup(func() { database.Callback().Create().Remove(callbackName) })
+
+	result, err := Demo(database, DemoOptions{Email: email, DisplayName: "不应覆盖", Password: "loser-password"})
+
+	require.NoError(t, err)
+	require.True(t, injected.Load())
+	require.Equal(t, "并发胜出用户", result.User.DisplayName)
+	require.NoError(t, bcrypt.CompareHashAndPassword([]byte(result.User.PasswordHash), []byte("winner-password")))
+	require.Error(t, bcrypt.CompareHashAndPassword([]byte(result.User.PasswordHash), []byte("loser-password")))
+	var userCount int64
+	require.NoError(t, database.Model(&models.SenlinAgentUser{}).Where("email = ?", email).Count(&userCount).Error)
+	require.Equal(t, int64(1), userCount)
+}
+
+func TestDemoSeedRetriesSerializationFailureOutsideTheTransaction(t *testing.T) {
+	database := newTestDB(t)
+	var failures atomic.Int32
+	callbackName := "test:fail_first_seed_user_create"
+	require.NoError(t, database.Callback().Create().Before("gorm:create").Register(callbackName, func(tx *gorm.DB) {
+		if tx.Statement.Schema == nil || tx.Statement.Schema.Table != (models.SenlinAgentUser{}).TableName() {
+			return
+		}
+		if failures.Add(1) == 1 {
+			tx.AddError(testSQLStateError{state: "40001"})
+		}
+	}))
+	t.Cleanup(func() { database.Callback().Create().Remove(callbackName) })
+
+	result, err := Demo(database, DemoOptions{Email: "retry@senlin.ai", DisplayName: "重试用户", Password: "password123"})
+
+	require.NoError(t, err)
+	require.Equal(t, int32(2), failures.Load())
+	require.Equal(t, "retry@senlin.ai", result.User.Email)
+	var userCount int64
+	require.NoError(t, database.Model(&models.SenlinAgentUser{}).Where("email = ?", result.User.Email).Count(&userCount).Error)
+	require.Equal(t, int64(1), userCount)
+}
+
+type testSQLStateError struct {
+	state string
+}
+
+func (err testSQLStateError) Error() string {
+	return "test PostgreSQL transaction failure " + err.state
+}
+
+func (err testSQLStateError) SQLState() string {
+	return err.state
+}
+
 func TestDemoSeedKeepsSameNamedTagsScopedToTheirProjects(t *testing.T) {
 	database := newTestDB(t)