feat(canvas): 创作助手 - 合并创作对话、能力发现与画布接续

backend/internal/database/creation_migration_test.go

@@ -0,0 +1,33 @@
+package database
+
+import (
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+	"infinite-canvas/backend/internal/model"
+	"testing"
+)
+
+func TestCreationMigrationKeepsLegacyTasksNullableAndEnforcesSubmissionUnique(t *testing.T) {
+	db, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = migrateSchemaV10(db); err != nil {
+		t.Fatal(err)
+	}
+	for _, id := range []string{"manual-one", "manual-two"} {
+		if err = db.Create(&model.Task{ID: id}).Error; err != nil {
+			t.Fatal(err)
+		}
+	}
+	sid := "submission"
+	if err = db.Create(&model.Task{ID: "creation-one", CreationSubmissionID: &sid}).Error; err != nil {
+		t.Fatal(err)
+	}
+	if err = db.Create(&model.Task{ID: "creation-two", CreationSubmissionID: &sid}).Error; err == nil {
+		t.Fatal("duplicate execution admitted")
+	}
+	if !db.Migrator().HasTable(&model.CreationRun{}) || !db.Migrator().HasTable(&model.CreationSubmission{}) {
+		t.Fatal("creation tables missing")
+	}
+}

backend/internal/database/migrations.go

@@ -10,7 +10,7 @@ import (
 	"gorm.io/gorm"
 )
 
-const CurrentSchemaVersion int64 = 9
+const CurrentSchemaVersion int64 = 10
 
 const baselineSchemaChecksum = "sha256:open-ai-canvas-schema-v1-20260830"
 const schemaMigrationAppliedAtIndexChecksum = "sha256:schema-migrations-applied-at-index-v2-20260830"
@@ -20,6 +20,7 @@ const paymentTopupChecksum = "sha256:payment-topup-v5-20260902"
 const resourcePlaybackChecksum = "sha256:resource-playback-v6-20260902"
 const assetLibraryFoldersChecksum = "sha256:asset-library-folders-v6-20260902"
 const logicalModelActiveCodeChecksum = "sha256:logical-model-active-code-v8-20260905"
+const creationRuntimeChecksum = "sha256:creation-runtime-v10-20260909"
 
 const postgresSchemaMigrationLockID int64 = 73123910420260830
 
@@ -55,6 +56,7 @@ var schemaMigrations = []migration{
 	{version: 7, name: "asset_library_folders", checksum: assetLibraryFoldersChecksum, apply: migrateSchemaV7},
 	{version: 8, name: "logical_model_active_code", checksum: logicalModelActiveCodeChecksum, apply: migrateSchemaV8},
 	{version: 9, name: "channel_presentation", checksum: "sha256:channel-presentation-v9-20260908", apply: migrateChannelPresentation},
+	{version: 10, name: "creation_runtime", checksum: creationRuntimeChecksum, apply: migrateSchemaV10},
 }
 
 func migrateChannelPresentation(tx *gorm.DB) error {
@@ -213,6 +215,14 @@ func migrateSchemaV8(tx *gorm.DB) error {
 	return nil
 }
 
+// migrateSchemaV10 只增加创作运行时表和任务幂等关联；旧任务的空 submission ID 必须继续合法。
+func migrateSchemaV10(tx *gorm.DB) error {
+	if err := tx.AutoMigrate(&model.CreationRun{}, &model.CreationSubmission{}, &model.Task{}); err != nil {
+		return fmt.Errorf("创建创作运行时结构：%w", err)
+	}
+	return nil
+}
+
 func MigrateSchema(db *gorm.DB) error {
 	return db.Transaction(func(tx *gorm.DB) error {
 		if tx.Dialector.Name() == "postgres" {

backend/internal/database/schema.go

@@ -87,6 +87,8 @@ func Models() []any {
 		&model.Announcement{},
 		&model.UserAnnouncementRead{},
 		&model.Task{},
+		&model.CreationRun{},
+		&model.CreationSubmission{},
 		&model.TaskTextDelta{},
 		&model.Session{},
 		&model.Message{},