set batch_size to 1 for engine tf deployment

infrastructure/terraform/lambda/engine/main.tf

@@ -24,8 +24,8 @@ module "lambda" {
 
   image_uri = local.image_uri
 
-  # Optional: Set maximum_concurrency to limit concurrent SQS-triggered invocations (2-1000)
   maximum_concurrency = var.maximum_concurrency
+  batch_size = var.batch_size
 
   environment = merge(
     {

infrastructure/terraform/lambda/engine/variables.tf

@@ -23,6 +23,11 @@ variable "maximum_concurrency" {
   description = "Maximum number of concurrent Lambda invocations from SQS (2-1000). null = no limit."
 }
 
+variable "batch_size" {
+  type    = number
+  default = 1
+}
+
 variable "db_host" {
   type      = string
   sensitive = true