fix(backend): harden write registrar boundaries

backend/internal/logic/tasks/concurrency_postgres_test.go

@@ -0,0 +1,94 @@
+package tasks
+
+import (
+	"fmt"
+	"os"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"gorm.io/driver/postgres"
+	"gorm.io/gorm"
+	"senlinai-agent/backend/internal/models"
+)
+
+func TestPostgresMovePreventsOldProjectShareFromBeingInsertedConcurrently(t *testing.T) {
+	dsn := os.Getenv("DATABASE_URL")
+	if dsn == "" {
+		t.Skip("DATABASE_URL is not configured; skipping PostgreSQL row-lock concurrency test")
+	}
+	database, err := gorm.Open(postgres.Open(dsn), &gorm.Config{TranslateError: true})
+	require.NoError(t, err)
+	require.NoError(t, models.AutoMigrate(database))
+	suffix := fmt.Sprint(time.Now().UnixNano())
+	owner := models.SenlinAgentUser{Email: "lock-" + suffix + "@example.com", DisplayName: "Lock Owner", PasswordHash: "hash"}
+	require.NoError(t, database.Create(&owner).Error)
+	first := models.SenlinAgentProject{OwnerID: owner.ID, Name: "First", Identifier: "FIRST-" + suffix}
+	second := models.SenlinAgentProject{OwnerID: owner.ID, Name: "Second", Identifier: "SECOND-" + suffix}
+	require.NoError(t, database.Create(&first).Error)
+	require.NoError(t, database.Create(&second).Error)
+	task := models.SenlinAgentTask{ProjectID: first.ID, CreatedBy: owner.ID, Title: "Move", Status: "open"}
+	note := models.SenlinAgentNote{ProjectID: first.ID, CreatedBy: owner.ID, Title: "Old context", Markdown: "private"}
+	require.NoError(t, database.Create(&task).Error)
+	require.NoError(t, database.Create(&note).Error)
+	t.Cleanup(func() {
+		database.Where("task_id = ?", task.ID).Delete(&models.SenlinAgentTaskShare{})
+		database.Where("entity_type = ? AND entity_id = ?", "task", task.ID).Delete(&models.SenlinAgentProjectEvent{})
+		database.Delete(&note)
+		database.Delete(&task)
+		database.Delete(&first)
+		database.Delete(&second)
+		database.Delete(&owner)
+	})
+
+	locked := make(chan struct{})
+	release := make(chan struct{})
+	var once sync.Once
+	var releaseOnce sync.Once
+	releaseLock := func() { releaseOnce.Do(func() { close(release) }) }
+	t.Cleanup(releaseLock)
+	callbackName := "test:pause_first_task_lock_" + suffix
+	require.NoError(t, database.Callback().Query().After("gorm:query").Register(callbackName, func(tx *gorm.DB) {
+		if tx.Statement.Schema == nil || tx.Statement.Schema.Table != (models.SenlinAgentTask{}).TableName() {
+			return
+		}
+		if _, ok := tx.Statement.Clauses["FOR"]; !ok {
+			return
+		}
+		once.Do(func() {
+			close(locked)
+			<-release
+		})
+	}))
+	t.Cleanup(func() { database.Callback().Query().Remove(callbackName) })
+
+	service := NewService(database)
+	moveResult := make(chan error, 1)
+	go func() {
+		_, err := service.Update(owner.ID, first.Identity, task.Identity, UpdateTaskInput{
+			Title: task.Title, NextProjectIdentity: second.Identity,
+		})
+		moveResult <- err
+	}()
+	select {
+	case <-locked:
+	case <-time.After(5 * time.Second):
+		t.Fatal("timed out waiting for Update to acquire the task row lock")
+	}
+
+	shareResult := make(chan error, 1)
+	go func() { shareResult <- service.ShareObject(task.ID, "note", note.ID) }()
+	select {
+	case err := <-shareResult:
+		t.Fatalf("ShareObject returned before the moving transaction released its task lock: %v", err)
+	case <-time.After(150 * time.Millisecond):
+	}
+	releaseLock()
+	require.NoError(t, <-moveResult)
+	require.ErrorContains(t, <-shareResult, "shared object not found in task project")
+
+	var shareCount int64
+	require.NoError(t, database.Model(&models.SenlinAgentTaskShare{}).Where("task_id = ?", task.ID).Count(&shareCount).Error)
+	require.Zero(t, shareCount)
+}