diff --git a/sqs-lambda-tenant-isolation-sam-py/sqs-processor/index.py b/sqs-lambda-tenant-isolation-sam-py/sqs-processor/index.py
index fca8a902d..480e6049a 100644
--- a/sqs-lambda-tenant-isolation-sam-py/sqs-processor/index.py
+++ b/sqs-lambda-tenant-isolation-sam-py/sqs-processor/index.py
@@ -1,29 +1,53 @@
 import json
+import re
+import sys
 import boto3
 import os
+from botocore.exceptions import ClientError
 
 lambda_client = boto3.client('lambda')
 TENANT_ISOLATED_FUNCTION = os.environ['TENANT_ISOLATED_FUNCTION_NAME']
 
+TENANT_ID_PATTERN = re.compile(r'^[a-zA-Z0-9-]{1,64}$')
+MAX_BODY_SIZE_BYTES = 262144  # 256 KB
+
 def handler(event, context):
     for record in event['Records']:
-        body = json.loads(record['body'])
-        
-        # Get message group ID from SQS attributes
+        try:
+            body = json.loads(record['body'])
+        except json.JSONDecodeError as e:
+            print(f"Failed to parse message body: {e}")
+            continue
+
+        body_size = sys.getsizeof(record['body'])
+        if body_size > MAX_BODY_SIZE_BYTES:
+            print(f"Message body exceeds max size ({body_size} > {MAX_BODY_SIZE_BYTES}), skipping")
+            continue
+
+        if not isinstance(body, dict):
+            print(f"Message body is not a JSON object, skipping")
+            continue
+
         attributes = record.get('attributes') or {}
         message_group_id = attributes.get('MessageGroupId')
-        
+
         if not message_group_id:
-            print(f"Missing MessageGroupId in SQS record: {record}")
-            message_group_id = "default"
-        
-        lambda_client.invoke(
-            FunctionName=TENANT_ISOLATED_FUNCTION,
-            InvocationType='Event',
-            Payload=json.dumps(body),
-            TenantId=message_group_id
-        )
-        
+            raise ValueError("MessageGroupId is required for tenant isolation")
+
+        if not TENANT_ID_PATTERN.match(message_group_id):
+            raise ValueError(f"Invalid tenant ID format: {message_group_id}")
+
+        try:
+            lambda_client.invoke(
+                FunctionName=TENANT_ISOLATED_FUNCTION,
+                InvocationType='Event',
+                Payload=json.dumps(body),
+                TenantId=message_group_id
+            )
+        except ClientError as e:
+            print(f"Lambda invocation failed for tenant {message_group_id}: {e}")
+            raise  # Let SQS retry
+
         print(f"Invoked tenant-isolated function for messagegroup: {message_group_id}")
-    
+
     return {'statusCode': 200}
diff --git a/sqs-lambda-tenant-isolation-sam-py/template.yml b/sqs-lambda-tenant-isolation-sam-py/template.yml
index 080cfa065..3cfb3740c 100644
--- a/sqs-lambda-tenant-isolation-sam-py/template.yml
+++ b/sqs-lambda-tenant-isolation-sam-py/template.yml
@@ -3,11 +3,52 @@ Transform: AWS::Serverless-2016-10-31
 Description: Lambda Tenant Isolation Demo
 
 Resources:
+  DeadLetterQueue:
+    Type: AWS::SQS::Queue
+    Properties:
+      QueueName: tenant-isolation-dlq
+      SqsManagedSseEnabled: true
+      MessageRetentionPeriod: 1209600  # 14 days
+
   ProcessingQueue:
     Type: AWS::SQS::Queue
     Properties:
       QueueName: tenant-isolation-queue
       VisibilityTimeout: 300
+      SqsManagedSseEnabled: true
+      RedrivePolicy:
+        deadLetterTargetArn: !GetAtt DeadLetterQueue.Arn
+        maxReceiveCount: 3
+
+  QueuePolicy:
+    Type: AWS::SQS::QueuePolicy
+    Properties:
+      Queues:
+        - !Ref ProcessingQueue
+      PolicyDocument:
+        Statement:
+          - Sid: DenyInsecureTransport
+            Effect: Deny
+            Principal: '*'
+            Action: 'sqs:*'
+            Resource: !GetAtt ProcessingQueue.Arn
+            Condition:
+              Bool:
+                'aws:SecureTransport': 'false'
+          - Sid: AllowSameAccountSendMessage
+            Effect: Allow
+            Principal:
+              AWS: !Sub 'arn:aws:iam::${AWS::AccountId}:root'
+            Action: 'sqs:SendMessage'
+            Resource: !GetAtt ProcessingQueue.Arn
+          - Sid: DenyExternalSendMessage
+            Effect: Deny
+            Principal: '*'
+            Action: 'sqs:SendMessage'
+            Resource: !GetAtt ProcessingQueue.Arn
+            Condition:
+              StringNotEquals:
+                'aws:PrincipalAccount': !Ref AWS::AccountId
 
   TenantIsolatedFunctionRole:
     Type: AWS::IAM::Role
@@ -34,6 +75,34 @@ Resources:
       TenancyConfig:
         TenantIsolationMode: PER_TENANT
 
+  SQSProcessorFunctionRole:
+    Type: AWS::IAM::Role
+    Properties:
+      AssumeRolePolicyDocument:
+        Version: '2012-10-17'
+        Statement:
+          - Effect: Allow
+            Principal:
+              Service: lambda.amazonaws.com
+            Action: sts:AssumeRole
+      ManagedPolicyArns:
+        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
+      Policies:
+        - PolicyName: SQSProcessorPolicy
+          PolicyDocument:
+            Version: '2012-10-17'
+            Statement:
+              - Effect: Allow
+                Action:
+                  - sqs:ReceiveMessage
+                  - sqs:DeleteMessage
+                  - sqs:GetQueueAttributes
+                Resource: !GetAtt ProcessingQueue.Arn
+              - Effect: Allow
+                Action:
+                  - lambda:InvokeFunction
+                Resource: !GetAtt TenantIsolatedFunction.Arn
+
   SQSProcessorFunction:
     Type: AWS::Serverless::Function
     Properties:
@@ -42,21 +111,17 @@ Resources:
       Handler: index.handler
       Runtime: python3.12
       Timeout: 60
+      Role: !GetAtt SQSProcessorFunctionRole.Arn
       Environment:
         Variables:
           TENANT_ISOLATED_FUNCTION_NAME: !Ref TenantIsolatedFunction
-      Policies:
-        - Statement:
-          - Effect: Allow
-            Action:
-              - lambda:InvokeFunction
-            Resource: !GetAtt TenantIsolatedFunction.Arn
       Events:
         SQSEvent:
           Type: SQS
           Properties:
             Queue: !GetAtt ProcessingQueue.Arn
             BatchSize: 10
+  
 
 Outputs:
   QueueUrl:
diff --git a/sqs-lambda-tenant-isolation-sam-py/tenant-isolated-processor/index.py b/sqs-lambda-tenant-isolation-sam-py/tenant-isolated-processor/index.py
index d5432f88e..670e99350 100644
--- a/sqs-lambda-tenant-isolation-sam-py/tenant-isolated-processor/index.py
+++ b/sqs-lambda-tenant-isolation-sam-py/tenant-isolated-processor/index.py
@@ -1,16 +1,28 @@
 import json
+import re
+
+TENANT_ID_PATTERN = re.compile(r'^[a-zA-Z0-9-]{1,64}$')
 
 def handler(event, context):
     tenant_id = context.tenant_id
-    
+
+    if not tenant_id:
+        raise ValueError("tenant_id is missing from context")
+
+    if not TENANT_ID_PATTERN.match(tenant_id):
+        raise ValueError(f"Invalid tenant ID format: {tenant_id}")
+
+    if not isinstance(event, dict):
+        raise ValueError(f"Expected event to be a dict, got {type(event).__name__}")
+
     print(f"Processing request for tenant: {tenant_id}")
     print(f"Event data: {json.dumps(event)}")
-    
+
     # Process tenant-specific logic here
     result = {
         'tenant_id': tenant_id,
         'message': 'Request processed successfully',
         'data': event
     }
-    
+
     return result