diff --git a/serverless.yml b/serverless.yml
index c27c0658..f3def028 100644
--- a/serverless.yml
+++ b/serverless.yml
@@ -1,18 +1,10 @@
 service: retrofit-platform
 
-frameworkVersion: '3'
-
 provider:
   name: aws
   region: eu-west-2
+  runtime: python3.11
   architecture: x86_64
-
-  # REQUIRED for TRUE image Lambdas in Serverless v3
-  ecr:
-    images:
-      modelEngineImage:
-        uri: ${env:ECR_URI}:${env:GITHUB_SHA}
-
   environment:
     API_KEY: ${env:API_KEY}
     ENVIRONMENT: ${env:ENVIRONMENT}
@@ -27,6 +19,8 @@ provider:
     DB_USERNAME: ${env:DB_USERNAME}
     DB_PASSWORD: ${env:DB_PASSWORD}
     DB_PORT: ${env:DB_PORT}
+    ECR_URI: ${env:ECR_URI}
+    GITHUB_SHA: ${env:GITHUB_SHA}
     SAP_PREDICTIONS_BUCKET: ${env:SAP_PREDICTIONS_BUCKET}
     CARBON_PREDICTIONS_BUCKET: ${env:CARBON_PREDICTIONS_BUCKET}
     HEAT_PREDICTIONS_BUCKET: ${env:HEAT_PREDICTIONS_BUCKET}
@@ -45,8 +39,6 @@ custom:
   pythonRequirements:
     fileName: backend/app/requirements/requirements.txt
     dockerizePip: true
-    pythonBin: python3.11
-
   customDomain:
     domainName: api.${self:provider.environment.DOMAIN_NAME}
     createRoute53Record: true
@@ -54,11 +46,7 @@ custom:
 
 functions:
 
-  # ─────────────────────────────────────────────
-  # ZIP-BASED FASTAPI LAMBDA
-  # ─────────────────────────────────────────────
   fastapi-backend:
-    runtime: python3.11
     handler: backend.app.main.handler
     timeout: 600
     memorySize: 512
@@ -68,29 +56,26 @@ functions:
           path: /{proxy+}
           method: ANY
 
-  # ─────────────────────────────────────────────
-  # TRUE CONTAINER-IMAGE LAMBDA (4GB+ SUPPORTED)
-  # ─────────────────────────────────────────────
   model-engine-lambda:
     image:
-      name: modelEngineImage
+      uri: ${env:ECR_URI}:${env:GITHUB_SHA}
     timeout: 900
-    memorySize: 4096
+    memorySize: 3008
     role: EngineLambdaRole
     events:
       - sqs:
           arn: arn:aws:sqs:${self:provider.region}:${aws:accountId}:model-engine-queue
           batchSize: 1
-          maximumConcurrency: 12
+          maximumConcurrency: 12  # Heavily restricts concurrency to avoid overwhelming the ldmbda limits
+
 
 resources:
   Resources:
-
     EngineQueue:
       Type: AWS::SQS::Queue
       Properties:
         QueueName: model-engine-queue
-        VisibilityTimeout: 910
+        VisibilityTimeout: 910 # must be >= lambda timeout (900)
 
     FastApiLambdaRole:
       Type: AWS::IAM::Role