fix(11-08): refuse unmanaged after-commit work

modules/lagoon/transaction.go

@@ -52,6 +52,9 @@ func Transaction(ctx context.Context, gdb *gorm.DB, fn func(ctx context.Context,
 		ctx = context.Background()
 	}
 	if parent, ok := ctx.Value(afterCommitKey{}).(*afterCommitBuffer); ok && parent != nil {
+		if !transactionalHandle(gdb) {
+			return fmt.Errorf("lagoon: nested transaction requires the parent transaction handle")
+		}
 		child := &afterCommitBuffer{}
 		childCtx := context.WithValue(ctx, afterCommitKey{}, child)
 		err := gdb.WithContext(childCtx).Transaction(func(tx *gorm.DB) error {
@@ -79,8 +82,9 @@ func Transaction(ctx context.Context, gdb *gorm.DB, fn func(ctx context.Context,
 // single-statement write for which GORM opened its own transaction (for
 // example from a GORM create callback) it runs after that commit through the
 // AfterCommitCallback callback, and not at all when the write fails.
-// Anywhere else, including inside a plain gorm Transaction, fn runs
-// immediately on db's connection.
+// Inside a foreign plain GORM transaction it logs a warning and refuses to
+// run, because Lagoon cannot know whether that transaction will commit.
+// Anywhere else, fn runs immediately on db's connection.
 //
 // The handle fn receives always has an empty statement on the connection
 // the work belongs to (the pool after a commit, the open transaction
@@ -113,10 +117,22 @@ func AfterCommit(ctx context.Context, db *gorm.DB, fn func(ctx context.Context,
 			db.InstanceSet(statementBufferKey, buf)
 			return
 		}
+		if transactionalHandle(db) {
+			slog.Default().Warn("lagoon: after-commit callback skipped inside unmanaged transaction")
+			return
+		}
 	}
 	runAfterCommit(ctx, cleanHandle(db, ctx), []func(context.Context, *gorm.DB){fn})
 }
 
+func transactionalHandle(db *gorm.DB) bool {
+	if db == nil || db.Statement == nil || db.Statement.ConnPool == nil {
+		return false
+	}
+	_, ok := db.Statement.ConnPool.(gorm.TxCommitter)
+	return ok
+}
+
 func bufferFrom(ctx context.Context, db *gorm.DB) *afterCommitBuffer {
 	if buf, ok := ctx.Value(afterCommitKey{}).(*afterCommitBuffer); ok && buf != nil {
 		return buf