diff --git a/lambda-ddb-tenant-isolation-terraform/README.md b/lambda-ddb-tenant-isolation-terraform/README.md
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+# Multi-tenant API with Amazon API Gateway and AWS Lambda Tenant Isolation
+
+![architecture](architecture/architecture.png)
+
+This pattern implements a serverless multi-tenant counter API using Amazon API Gateway, AWS Lambda and Amazon DynamoDB. It deploys two parallel endpoints, one without tenant isolation and one with full per-tenant isolation, to demonstrate how shared state leads to cross-tenant data leakage in multi-tenant applications.
+
+When a request hits the standard endpoint, the Lambda function increments a single shared counter in DynamoDB, exposing activity across all tenants. The isolated endpoint requires a tenant ID header, which maps to a dedicated Lambda execution environment and a tenant-specific DynamoDB row. Each tenant gets an independent counter, ensuring complete data separation. 
+
+Please note that this pattern deploys API Gateway endpoints with no authorization. Production deployments should secure all endpoints with an appropriate authorization mechanism such as AWS IAM authorization, Amazon Cognito user pools, or API key usage plans.
+
+Learn more about this pattern at Serverless Land Patterns: https://serverlessland.com/patterns/lambda-ddb-tenant-isolation-terraform
+
+Important: this application uses various AWS services and there are costs associated with these services after the Free Tier usage - please see the [AWS Pricing page](https://aws.amazon.com/pricing/) for details. You are responsible for any AWS costs incurred. No warranty is implied in this example.
+
+## Requirements
+
+* [Create an AWS account](https://portal.aws.amazon.com/gp/aws/developer/registration/index.html) if you do not already have one and log in. The IAM user that you use must have sufficient permissions to make necessary AWS service calls and manage AWS resources.
+* [AWS CLI](https://docs.aws.amazon.com/cli/latest/userguide/install-cliv2.html) installed and configured
+* [Git Installed](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git)
+* [Terraform](https://learn.hashicorp.com/tutorials/terraform/install-cli?in=terraform/aws-get-started) installed
+
+## Deployment Instructions
+
+1. Create a new directory, navigate to that directory in a terminal and clone the GitHub repository:
+    ``` 
+    git clone https://github.com/aws-samples/serverless-patterns
+    ```
+1. Change directory to the pattern directory:
+    ```
+    cd lambda-ddb-tenant-isolation-terraform
+    ```
+1. From the command line, initialize terraform to downloads and installs the providers defined in the configuration:
+    ```
+    terraform init
+    ```
+1. From the command line, apply the configuration in the main.tf file:
+    ```
+    terraform apply -auto-approve
+    ```
+1. During the prompts
+    #var.aws_region
+    - Enter a value: {enter the region for deployment}
+
+    #var.prefix
+    - Enter a value: {enter any prefix to associate with resources}
+
+1. Note the outputs from the Terraform deployment process. These contain the resource names and/or ARNs which are used for testing.
+
+## Testing
+
+Use [curl](https://curl.se/) to send a HTTP GET request to the API.
+
+1. Make a GET request to the Standard API endpoint using the following cURL command:
+```
+curl -H "x-tenant-id: TENANT_ID" "STANDARD_API_ENDPOINT"
+```
+Note: Replace the `TENANT_ID` with a unique Tenant ID of your choice and `STANDARD_API_ENDPOINT` with the generated `standard_multi_tenant_api_endpoint_url` from Terraform (refer to the Terraform Outputs section)
+
+For ex,
+```
+curl -H "x-tenant-id: Tenant-1" "https://1234abcde.execute-api.us-east-1.amazonaws.com/dev/standard"
+```
+
+The response would be,
+```
+{"counter": 1, "tenant_id": "Tenant-1", "isolation_enabled": false, "message": "This function does NOT provide tenant isolation and every tenant reads and writes the same DynamoDB row. Incremented counter is shared across all the tenants"}
+```
+
+Test this for another Tenant ID. For ex,
+```
+curl -H "x-tenant-id: Tenant-2" "https://1234abcde.execute-api.us-east-1.amazonaws.com/dev/standard"
+```
+
+The response would be,
+```
+{"counter": 2, "tenant_id": "Tenant-2", "isolation_enabled": false, "message": "This function does NOT provide tenant isolation and every tenant reads and writes the same DynamoDB row. Incremented counter is shared across all the tenants"}
+```
+
+1. Now make a GET request to the Isolated API endpoint using the following cURL command:
+```
+curl -H "x-tenant-id: TENANT_ID" "ISOLATED_API_ENDPOINT"
+```
+Note: Replace the `TENANT_ID` with a unique Tenant ID of your choice and `ISOLATED_API_ENDPOINT` with the generated `isolated_tenant_api_endpoint_url` from Terraform (refer to the Terraform Outputs section)
+
+For ex,
+```
+curl -H "x-tenant-id: Tenant-1" "https://1234abcde.execute-api.us-east-1.amazonaws.com/dev/isolated"
+```
+
+The response would be,
+```
+{"counter": 1, "tenant_id": "Tenant-1", "isolation_enabled": true, "message": "Counter incremented for tenant Tenant-1"}
+```
+
+Test this for another Tenant ID. For ex,
+```
+curl -H "x-tenant-id: Tenant-2" "https://1234abcde.execute-api.us-east-1.amazonaws.com/dev/isolated"
+```
+
+The response would be,
+```
+{"counter": 2, "tenant_id": "Tenant-2", "isolation_enabled": true, "message": "Counter incremented for tenant Tenant-2"}
+```
+
+## Cleanup
+
+1. Change directory to the pattern directory:
+    ```
+    cd serverless-patterns/lambda-ddb-tenant-isolation-terraform
+    ```
+
+1. Delete all created resources
+    ```
+    terraform destroy -auto-approve
+    ```
+    
+1. During the prompts:
+    ```
+    Enter all details as entered during creation.
+    ```
+
+1. Confirm all created resources has been deleted
+    ```
+    terraform show
+    ```
+----
+Copyright 2026 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+
+SPDX-License-Identifier: MIT-0
\ No newline at end of file
diff --git a/lambda-ddb-tenant-isolation-terraform/architecture/architecture.png b/lambda-ddb-tenant-isolation-terraform/architecture/architecture.png
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diff --git a/lambda-ddb-tenant-isolation-terraform/example-pattern.json b/lambda-ddb-tenant-isolation-terraform/example-pattern.json
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+{
+  "title": "Multi-tenant API with Amazon API Gateway and AWS Lambda Tenant Isolation",
+  "description": "This pattern implements a serverless multi-tenant API using Amazon API Gateway, AWS Lambda and Amazon DynamoDB to demonstrate tenant isolation.",
+  "language": "Python",
+  "level": "200",
+  "framework": "Terraform",
+  "introBox": {
+    "headline": "How it works",
+    "text": [
+      "This solution works by exposing two API Gateway endpoints, /standard and /isolated, each backed by a separate Lambda function. When a request hits the /standard endpoint, the Lambda function increments a single shared counter row in DynamoDB, meaning all tenants read and write the same value. When a request hits the /isolated endpoint with an x-tenant-id header, API Gateway maps the header to the Lambda execution context, ensuring a dedicated execution environment per tenant, and the Lambda function increments a tenant-specific counter row in DynamoDB, keeping each tenant's data completely separate."
+
+    ]
+  },
+  "gitHub": {
+    "template": {
+      "repoURL": "https://github.com/aws-samples/serverless-patterns/tree/main/lambda-ddb-tenant-isolation-terraform",
+      "templateURL": "serverless-patterns/lambda-ddb-tenant-isolation-terraform",
+      "projectFolder": "lambda-ddb-tenant-isolation-terraform",
+      "templateFile": "main.tf"
+    }
+  },
+  "resources": {
+    "bullets": [
+      {
+        "text": "Lambda Tenant Isolation",
+        "link": "https://docs.aws.amazon.com/lambda/latest/dg/tenant-isolation.html"
+      }
+    ]
+  },
+  "deploy": {
+    "text": [
+      "terraform init",
+      "terraform apply"
+    ]
+  },
+  "testing": {
+    "text": [
+      "See the GitHub repo for detailed testing instructions."
+    ]
+  },
+  "cleanup": {
+    "text": [
+      "terraform destroy",
+      "terraform show"
+    ]
+  },
+  "authors": [
+    {
+      "name": "Archana V",
+      "image": "https://media.licdn.com/dms/image/v2/D5603AQGhkVtEhllFEw/profile-displayphoto-shrink_200_200/B56ZZH3LL6H0AY-/0/1744962369852?e=1772668800&v=beta&t=y0t7bsQKJwy5McO395hDmW7QPu_K-a1WKXeTA0-ecno",
+      "bio": "Solutions Architect at AWS",
+      "linkedin": "archanavenkat"
+    }
+  ]
+}
diff --git a/lambda-ddb-tenant-isolation-terraform/main.tf b/lambda-ddb-tenant-isolation-terraform/main.tf
new file mode 100644
index 0000000000..b92df76c62
--- /dev/null
+++ b/lambda-ddb-tenant-isolation-terraform/main.tf
@@ -0,0 +1,972 @@
+terraform {
+  required_version = ">= 1.0"
+  required_providers {
+    aws = {
+      source  = "hashicorp/aws"
+      version = "~> 6.31.0"
+    }
+    archive = {
+      source  = "hashicorp/archive"
+      version = "~> 2.0"
+    }
+  }
+}
+
+provider "aws" {
+  region = var.aws_region
+}
+
+# ──────────────────────────────────────────────
+# Variables — Terraform will prompt for prefix and region
+# ──────────────────────────────────────────────
+
+variable "aws_region" {
+  description = "AWS region for resources (e.g. us-east-1, us-west-2)"
+  type        = string
+
+  validation {
+    condition     = can(regex("^[a-z]{2}-[a-z]+-[0-9]+$", var.aws_region))
+    error_message = "Must be a valid AWS region (e.g. us-east-1, eu-west-2)."
+  }
+}
+
+variable "prefix" {
+  description = "Unique prefix for all resource names — avoids collisions (e.g. your initials or team name)"
+  type        = string
+
+  validation {
+    condition     = can(regex("^[a-z0-9][a-z0-9\\-]{1,20}$", var.prefix))
+    error_message = "Prefix must be 2-21 lowercase alphanumeric characters or hyphens, starting with a letter or number."
+  }
+}
+
+variable "environment" {
+  description = "Environment name for resource naming"
+  type        = string
+  default     = "dev"
+  validation {
+    condition     = contains(["dev", "staging", "prod"], var.environment)
+    error_message = "Environment must be dev, staging, or prod."
+  }
+}
+
+variable "log_retention_days" {
+  description = "CloudWatch log retention in days (0 = never expire)"
+  type        = number
+  default     = 14
+}
+
+# ──────────────────────────────────────────────
+# Locals — single place that builds the name prefix
+# ──────────────────────────────────────────────
+
+locals {
+  name_prefix = "${var.prefix}-tenant-iso"
+}
+
+# Data sources
+data "aws_caller_identity" "current" {}
+data "aws_region" "current" {}
+
+# ──────────────────────────────────────────────
+# Inline Lambda Code → ZIP archives
+# ──────────────────────────────────────────────
+
+data "archive_file" "standard_lambda_zip" {
+  type        = "zip"
+  output_path = "${path.module}/standard_lambda_function.zip"
+
+  source {
+    content  = <<-PYTHON
+import json
+import logging
+import os
+
+import boto3
+from botocore.exceptions import ClientError
+
+logger = logging.getLogger()
+logger.setLevel(logging.INFO)
+
+TABLE_NAME = os.environ["TABLE_NAME"]
+dynamodb = boto3.resource("dynamodb")
+table = dynamodb.Table(TABLE_NAME)
+
+# The single partition key every tenant shares — the core of the problem.
+SHARED_KEY = "SHARED"
+
+
+def lambda_handler(event, context):
+    """
+    Standard Lambda handler WITHOUT tenant isolation.
+
+    All tenants share a single DynamoDB row, so every call — regardless
+    of which tenant makes it — increments the same counter.  This is the
+    multi-tenant anti-pattern this demo exists to highlight.
+    """
+    try:
+        if not isinstance(event, dict):
+            return _error(400, "Bad Request", "Invalid request format")
+
+        headers = event.get("headers", {}) or {}
+        tenant_id_from_header = (
+            headers.get("x-tenant-id")
+            or headers.get("Tenant-Id")
+            or headers.get("TENANT-ID")
+        )
+
+        logger.info(
+            "Processing standard request — Method: %s, Path: %s, Tenant Header: %s",
+            event.get("httpMethod", "UNKNOWN"),
+            event.get("path", "UNKNOWN"),
+            tenant_id_from_header,
+        )
+
+        http_method = event.get("httpMethod", "")
+        if not http_method:
+            return _error(400, "Bad Request", "Missing HTTP method in request")
+        if http_method != "GET":
+            return _error(
+                405,
+                "Method Not Allowed",
+                f"HTTP method {http_method} is not supported. Only GET requests are allowed.",
+            )
+
+        # ── Atomic increment on the SHARED row ──────────────────────
+        response = table.update_item(
+            Key={"pk": SHARED_KEY},
+            UpdateExpression="SET #c = if_not_exists(#c, :zero) + :inc",
+            ExpressionAttributeNames={"#c": "counter"},
+            ExpressionAttributeValues={":zero": 0, ":inc": 1},
+            ReturnValues="UPDATED_NEW",
+        )
+        counter = int(response["Attributes"]["counter"])
+
+        if tenant_id_from_header:
+            logger.warning(
+                "PROBLEM: Tenant '%s' is using SHARED counter value %d! "
+                "This demonstrates data leakage between tenants.",
+                tenant_id_from_header,
+                counter,
+            )
+        else:
+            logger.info("Request without tenant header — shared counter: %d", counter)
+
+        body = {
+            "counter": counter,
+            "tenant_id": tenant_id_from_header,
+            "isolation_enabled": False,
+            "message": (
+                f"This function does NOT provide tenant isolation and every tenant reads and writes the same DynamoDB row. Incremented counter is shared across all the tenants"
+            ),
+        }
+
+        return {
+            "statusCode": 200,
+            "headers": {
+                "Content-Type": "application/json",
+                "Cache-Control": "no-cache",
+            },
+            "body": json.dumps(body),
+        }
+
+    except ClientError as exc:
+        logger.error("DynamoDB error: %s", exc.response["Error"]["Message"], exc_info=True)
+        return _error(500, "Internal Server Error", "Database error while updating counter")
+    except Exception:
+        logger.error("Unexpected error processing request", exc_info=True)
+        return _error(500, "Internal Server Error", "An unexpected error occurred")
+
+
+def _error(status_code, error_type, message):
+    return {
+        "statusCode": status_code,
+        "headers": {
+            "Content-Type": "application/json",
+            "Cache-Control": "no-cache",
+        },
+        "body": json.dumps(
+            {"error": error_type, "message": message, "statusCode": status_code}
+        ),
+    }
+    PYTHON
+    filename = "standard_lambda_function.py"
+  }
+}
+
+data "archive_file" "isolated_lambda_zip" {
+  type        = "zip"
+  output_path = "${path.module}/isolated_lambda_function.zip"
+
+  source {
+    content  = <<-PYTHON
+import json
+import logging
+import os
+import re
+
+import boto3
+from botocore.exceptions import ClientError
+
+logger = logging.getLogger()
+logger.setLevel(logging.INFO)
+
+TABLE_NAME = os.environ["TABLE_NAME"]
+dynamodb = boto3.resource("dynamodb")
+table = dynamodb.Table(TABLE_NAME)
+
+# Simple allowlist for tenant IDs — alphanumeric, hyphens, underscores.
+TENANT_ID_PATTERN = re.compile(r"^[\w\-]{1,100}$")
+
+
+def lambda_handler(event, context):
+    """
+    Tenant-isolated Lambda handler.
+
+    * The Lambda runtime guarantees a dedicated execution environment per
+      tenant (`PER_TENANT` isolation mode).
+    * Each tenant's counter is stored in its own DynamoDB row keyed by
+      ``tenant_id``, so even at the data layer there is no sharing.
+    """
+    try:
+        if not isinstance(event, dict):
+            return _error(400, "Bad Request", "Invalid request format")
+
+        logger.info(
+            "Processing isolated request — Method: %s, Path: %s",
+            event.get("httpMethod", "UNKNOWN"),
+            event.get("path", "UNKNOWN"),
+        )
+
+        http_method = event.get("httpMethod", "")
+        if not http_method:
+            return _error(400, "Bad Request", "Missing HTTP method in request")
+        if http_method != "GET":
+            return _error(
+                405,
+                "Method Not Allowed",
+                f"HTTP method {http_method} is not supported. Only GET requests are allowed.",
+            )
+
+        # ── Resolve tenant ID from Lambda context ───────────────────
+        tenant_id = getattr(context, "tenant_id", None)
+
+        if not tenant_id:
+            logger.error("Missing tenant_id in Lambda context")
+            return _error(
+                400,
+                "Missing Tenant ID",
+                "Tenant ID is required. Ensure the x-tenant-id header is provided.",
+            )
+
+        tenant_id = tenant_id.strip()
+
+        if not TENANT_ID_PATTERN.match(tenant_id):
+            logger.error("Invalid tenant ID format: %s", tenant_id)
+            return _error(
+                400,
+                "Invalid Tenant ID",
+                "Tenant ID must be 1-100 alphanumeric, hyphen, or underscore characters.",
+            )
+
+        # ── Atomic per-tenant increment ─────────────────────────────
+        response = table.update_item(
+            Key={"tenant_id": tenant_id},
+            UpdateExpression="SET #c = if_not_exists(#c, :zero) + :inc",
+            ExpressionAttributeNames={"#c": "counter"},
+            ExpressionAttributeValues={":zero": 0, ":inc": 1},
+            ReturnValues="UPDATED_NEW",
+        )
+        counter = int(response["Attributes"]["counter"])
+
+        logger.info("Tenant '%s' — isolated counter now at %d", tenant_id, counter)
+
+        body = {
+            "counter": counter,
+            "tenant_id": tenant_id,
+            "isolation_enabled": True,
+            "message": f"Counter incremented for tenant {tenant_id}",
+        }
+
+        return {
+            "statusCode": 200,
+            "headers": {
+                "Content-Type": "application/json",
+                "Cache-Control": "no-cache",
+            },
+            "body": json.dumps(body),
+        }
+
+    except ClientError as exc:
+        logger.error("DynamoDB error: %s", exc.response["Error"]["Message"], exc_info=True)
+        return _error(500, "Internal Server Error", "Database error while updating counter")
+    except Exception:
+        logger.error("Unexpected error processing isolated request", exc_info=True)
+        return _error(500, "Internal Server Error", "An unexpected error occurred")
+
+
+def _error(status_code, error_type, message):
+    return {
+        "statusCode": status_code,
+        "headers": {
+            "Content-Type": "application/json",
+            "Cache-Control": "no-cache",
+        },
+        "body": json.dumps(
+            {"error": error_type, "message": message, "statusCode": status_code}
+        ),
+    }
+    PYTHON
+    filename = "isolated_lambda_function.py"
+  }
+}
+
+# ──────────────────────────────────────────────
+# DynamoDB Tables
+# ──────────────────────────────────────────────
+
+resource "aws_dynamodb_table" "shared_counter_table" {
+  name         = "${local.name_prefix}-shared-counters"
+  billing_mode = "PAY_PER_REQUEST"
+  hash_key     = "pk"
+
+  attribute {
+    name = "pk"
+    type = "S"
+  }
+
+  tags = {
+    Environment = var.environment
+    Prefix      = var.prefix
+    Purpose     = "Shared counter - demonstrates lack of tenant isolation"
+  }
+}
+
+resource "aws_dynamodb_table" "isolated_counter_table" {
+  name         = "${local.name_prefix}-isolated-counters"
+  billing_mode = "PAY_PER_REQUEST"
+  hash_key     = "tenant_id"
+
+  attribute {
+    name = "tenant_id"
+    type = "S"
+  }
+
+  tags = {
+    Environment = var.environment
+    Prefix      = var.prefix
+    Purpose     = "Per-tenant counters with tenant isolation"
+  }
+}
+
+# ──────────────────────────────────────────────
+# IAM — Per-function roles with least-privilege DynamoDB access
+# ──────────────────────────────────────────────
+
+# ──────────────── Standard Lambda Role ────────────────
+
+resource "aws_iam_role" "standard_lambda_execution_role" {
+  name = "${local.name_prefix}-standard-lambda-role"
+
+  force_detach_policies = true
+
+  assume_role_policy = jsonencode({
+    Version = "2012-10-17"
+    Statement = [
+      {
+        Effect = "Allow"
+        Principal = {
+          Service = "lambda.amazonaws.com"
+        }
+        Action = "sts:AssumeRole"
+      }
+    ]
+  })
+
+  tags = {
+    Environment = var.environment
+    Prefix      = var.prefix
+  }
+}
+
+resource "aws_iam_role_policy_attachment" "standard_lambda_basic_execution" {
+  role       = aws_iam_role.standard_lambda_execution_role.name
+  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
+}
+
+resource "aws_iam_role_policy" "standard_dynamodb_policy" {
+  name = "${local.name_prefix}-standard-dynamodb"
+  role = aws_iam_role.standard_lambda_execution_role.id
+
+  policy = jsonencode({
+    Version = "2012-10-17"
+    Statement = [
+      {
+        Sid    = "AllowSharedTableOnly"
+        Effect = "Allow"
+        Action = [
+          "dynamodb:GetItem",
+          "dynamodb:PutItem",
+          "dynamodb:UpdateItem"
+        ]
+        Resource = aws_dynamodb_table.shared_counter_table.arn
+      }
+    ]
+  })
+}
+
+# ──────────────── Isolated Lambda Role ────────────────
+
+resource "aws_iam_role" "isolated_lambda_execution_role" {
+  name = "${local.name_prefix}-isolated-lambda-role"
+
+  force_detach_policies = true
+
+  assume_role_policy = jsonencode({
+    Version = "2012-10-17"
+    Statement = [
+      {
+        Effect = "Allow"
+        Principal = {
+          Service = "lambda.amazonaws.com"
+        }
+        Action = "sts:AssumeRole"
+      }
+    ]
+  })
+
+  tags = {
+    Environment = var.environment
+    Prefix      = var.prefix
+  }
+}
+
+resource "aws_iam_role_policy_attachment" "isolated_lambda_basic_execution" {
+  role       = aws_iam_role.isolated_lambda_execution_role.name
+  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
+}
+
+resource "aws_iam_role_policy" "isolated_dynamodb_policy" {
+  name = "${local.name_prefix}-isolated-dynamodb"
+  role = aws_iam_role.isolated_lambda_execution_role.id
+
+  policy = jsonencode({
+    Version = "2012-10-17"
+    Statement = [
+      {
+        Sid    = "AllowIsolatedTableOnly"
+        Effect = "Allow"
+        Action = [
+          "dynamodb:GetItem",
+          "dynamodb:PutItem",
+          "dynamodb:UpdateItem"
+        ]
+        Resource = aws_dynamodb_table.isolated_counter_table.arn
+      }
+    ]
+  })
+}
+
+# ──────────────────────────────────────────────
+# CloudWatch Log Groups (Terraform-managed, destroyed on terraform destroy)
+# ──────────────────────────────────────────────
+
+resource "aws_cloudwatch_log_group" "counter_standard_log_group" {
+  name              = "/aws/lambda/${local.name_prefix}-counter-standard"
+  retention_in_days = var.log_retention_days
+  skip_destroy      = false
+
+  tags = {
+    Environment = var.environment
+    Prefix      = var.prefix
+  }
+}
+
+resource "aws_cloudwatch_log_group" "counter_isolated_log_group" {
+  name              = "/aws/lambda/${local.name_prefix}-counter-isolated"
+  retention_in_days = var.log_retention_days
+  skip_destroy      = false
+
+  tags = {
+    Environment = var.environment
+    Prefix      = var.prefix
+  }
+}
+
+# ──────────────────────────────────────────────
+# Lambda Functions
+# ──────────────────────────────────────────────
+
+resource "aws_lambda_function" "counter_standard_function" {
+  filename         = data.archive_file.standard_lambda_zip.output_path
+  source_code_hash = data.archive_file.standard_lambda_zip.output_base64sha256
+  function_name    = "${local.name_prefix}-counter-standard"
+  role             = aws_iam_role.standard_lambda_execution_role.arn
+  handler          = "standard_lambda_function.lambda_handler"
+  runtime          = "python3.14"
+  timeout          = 25
+  memory_size      = 128
+  description      = "[${var.prefix}] Lambda without tenant isolation — shared DynamoDB counter"
+
+  logging_config {
+    log_group  = aws_cloudwatch_log_group.counter_standard_log_group.name
+    log_format = "Text"
+  }
+
+  environment {
+    variables = {
+      LOG_LEVEL  = "INFO"
+      TABLE_NAME = aws_dynamodb_table.shared_counter_table.name
+    }
+  }
+
+  tags = {
+    Environment = var.environment
+    Prefix      = var.prefix
+  }
+
+  depends_on = [
+    aws_cloudwatch_log_group.counter_standard_log_group,
+    aws_iam_role_policy_attachment.standard_lambda_basic_execution,
+    aws_iam_role_policy.standard_dynamodb_policy
+  ]
+}
+
+resource "aws_lambda_function" "counter_isolated_function" {
+  filename         = data.archive_file.isolated_lambda_zip.output_path
+  source_code_hash = data.archive_file.isolated_lambda_zip.output_base64sha256
+  function_name    = "${local.name_prefix}-counter-isolated"
+  role             = aws_iam_role.isolated_lambda_execution_role.arn
+  handler          = "isolated_lambda_function.lambda_handler"
+  runtime          = "python3.14"
+  timeout          = 25
+  memory_size      = 128
+  description      = "[${var.prefix}] Lambda with tenant isolation — per-tenant DynamoDB counter"
+
+  tenancy_config {
+    tenant_isolation_mode = "PER_TENANT"
+  }
+
+  logging_config {
+    log_group  = aws_cloudwatch_log_group.counter_isolated_log_group.name
+    log_format = "Text"
+  }
+
+  environment {
+    variables = {
+      LOG_LEVEL  = "INFO"
+      TABLE_NAME = aws_dynamodb_table.isolated_counter_table.name
+    }
+  }
+
+  tags = {
+    Environment = var.environment
+    Prefix      = var.prefix
+  }
+
+  depends_on = [
+    aws_cloudwatch_log_group.counter_isolated_log_group,
+    aws_iam_role_policy_attachment.isolated_lambda_basic_execution,
+    aws_iam_role_policy.isolated_dynamodb_policy
+  ]
+}
+
+# ──────────────────────────────────────────────
+# API Gateway REST API
+# ──────────────────────────────────────────────
+
+resource "aws_api_gateway_rest_api" "api_gateway" {
+  name        = "${local.name_prefix}-api"
+  description = "[${var.prefix}] API Gateway for Lambda tenant isolation demonstration"
+
+  endpoint_configuration {
+    types = ["REGIONAL"]
+  }
+
+  tags = {
+    Environment = var.environment
+    Prefix      = var.prefix
+  }
+}
+
+# Request Validator
+resource "aws_api_gateway_request_validator" "request_validator" {
+  name                        = "${local.name_prefix}-request-validator"
+  rest_api_id                 = aws_api_gateway_rest_api.api_gateway.id
+  validate_request_parameters = true
+  validate_request_body       = false
+}
+
+# Error Model
+resource "aws_api_gateway_model" "error_model" {
+  rest_api_id  = aws_api_gateway_rest_api.api_gateway.id
+  name         = "ErrorModel"
+  content_type = "application/json"
+
+  schema = jsonencode({
+    "$schema" = "http://json-schema.org/draft-04/schema#"
+    title     = "Error Schema"
+    type      = "object"
+    properties = {
+      error = {
+        type = "string"
+      }
+      message = {
+        type = "string"
+      }
+      statusCode = {
+        type = "integer"
+      }
+    }
+  })
+}
+
+# ──────────────── Standard endpoint ────────────────
+
+resource "aws_api_gateway_resource" "standard_resource" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  parent_id   = aws_api_gateway_rest_api.api_gateway.root_resource_id
+  path_part   = "standard"
+}
+
+resource "aws_api_gateway_method" "standard_method" {
+  rest_api_id   = aws_api_gateway_rest_api.api_gateway.id
+  resource_id   = aws_api_gateway_resource.standard_resource.id
+  http_method   = "GET"
+  authorization = "NONE"
+
+  request_parameters = {
+    "method.request.header.tenant-id" = false
+  }
+}
+
+resource "aws_api_gateway_integration" "standard_integration" {
+  rest_api_id             = aws_api_gateway_rest_api.api_gateway.id
+  resource_id             = aws_api_gateway_resource.standard_resource.id
+  http_method             = aws_api_gateway_method.standard_method.http_method
+  integration_http_method = "POST"
+  type                    = "AWS_PROXY"
+  uri                     = aws_lambda_function.counter_standard_function.invoke_arn
+
+  request_parameters = {
+    "integration.request.header.X-Amz-Tenant-Id" = "method.request.header.tenant-id"
+  }
+}
+
+resource "aws_api_gateway_method_response" "standard_response_200" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.standard_resource.id
+  http_method = aws_api_gateway_method.standard_method.http_method
+  status_code = "200"
+
+  response_models = {
+    "application/json" = "Empty"
+  }
+}
+
+resource "aws_api_gateway_method_response" "standard_response_405" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.standard_resource.id
+  http_method = aws_api_gateway_method.standard_method.http_method
+  status_code = "405"
+
+  response_models = {
+    "application/json" = aws_api_gateway_model.error_model.name
+  }
+}
+
+resource "aws_api_gateway_method_response" "standard_response_500" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.standard_resource.id
+  http_method = aws_api_gateway_method.standard_method.http_method
+  status_code = "500"
+
+  response_models = {
+    "application/json" = aws_api_gateway_model.error_model.name
+  }
+}
+
+# Standard OPTIONS (CORS)
+resource "aws_api_gateway_method" "standard_options_method" {
+  rest_api_id   = aws_api_gateway_rest_api.api_gateway.id
+  resource_id   = aws_api_gateway_resource.standard_resource.id
+  http_method   = "OPTIONS"
+  authorization = "NONE"
+}
+
+resource "aws_api_gateway_integration" "standard_options_integration" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.standard_resource.id
+  http_method = aws_api_gateway_method.standard_options_method.http_method
+  type        = "MOCK"
+
+  request_templates = {
+    "application/json" = "{\"statusCode\": 200}"
+  }
+}
+
+resource "aws_api_gateway_method_response" "standard_options_response_200" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.standard_resource.id
+  http_method = aws_api_gateway_method.standard_options_method.http_method
+  status_code = "200"
+
+  response_parameters = {
+    "method.response.header.Access-Control-Allow-Headers" = true
+    "method.response.header.Access-Control-Allow-Methods" = true
+    "method.response.header.Access-Control-Allow-Origin"  = true
+  }
+}
+
+resource "aws_api_gateway_integration_response" "standard_options_integration_response" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.standard_resource.id
+  http_method = aws_api_gateway_method.standard_options_method.http_method
+  status_code = aws_api_gateway_method_response.standard_options_response_200.status_code
+
+  response_parameters = {
+    "method.response.header.Access-Control-Allow-Headers" = "'Content-Type,X-Amz-Date,Authorization,X-Api-Key,X-Amz-Security-Token'"
+    "method.response.header.Access-Control-Allow-Methods" = "'GET,OPTIONS'"
+    "method.response.header.Access-Control-Allow-Origin"  = "'*'"
+  }
+
+  response_templates = {
+    "application/json" = ""
+  }
+}
+
+# ──────────────── Isolated endpoint ────────────────
+
+resource "aws_api_gateway_resource" "isolated_resource" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  parent_id   = aws_api_gateway_rest_api.api_gateway.root_resource_id
+  path_part   = "isolated"
+}
+
+resource "aws_api_gateway_method" "isolated_method" {
+  rest_api_id          = aws_api_gateway_rest_api.api_gateway.id
+  resource_id          = aws_api_gateway_resource.isolated_resource.id
+  http_method          = "GET"
+  authorization        = "NONE"
+  request_validator_id = aws_api_gateway_request_validator.request_validator.id
+
+  request_parameters = {
+    "method.request.header.x-tenant-id" = true
+  }
+}
+
+resource "aws_api_gateway_integration" "isolated_integration" {
+  rest_api_id             = aws_api_gateway_rest_api.api_gateway.id
+  resource_id             = aws_api_gateway_resource.isolated_resource.id
+  http_method             = aws_api_gateway_method.isolated_method.http_method
+  integration_http_method = "POST"
+  type                    = "AWS_PROXY"
+  uri                     = aws_lambda_function.counter_isolated_function.invoke_arn
+
+  request_parameters = {
+    "integration.request.header.X-Amz-Tenant-Id" = "method.request.header.x-tenant-id"
+  }
+}
+
+resource "aws_api_gateway_method_response" "isolated_response_200" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.isolated_resource.id
+  http_method = aws_api_gateway_method.isolated_method.http_method
+  status_code = "200"
+
+  response_models = {
+    "application/json" = "Empty"
+  }
+}
+
+resource "aws_api_gateway_method_response" "isolated_response_400" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.isolated_resource.id
+  http_method = aws_api_gateway_method.isolated_method.http_method
+  status_code = "400"
+
+  response_models = {
+    "application/json" = aws_api_gateway_model.error_model.name
+  }
+}
+
+resource "aws_api_gateway_method_response" "isolated_response_405" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.isolated_resource.id
+  http_method = aws_api_gateway_method.isolated_method.http_method
+  status_code = "405"
+
+  response_models = {
+    "application/json" = aws_api_gateway_model.error_model.name
+  }
+}
+
+resource "aws_api_gateway_method_response" "isolated_response_500" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.isolated_resource.id
+  http_method = aws_api_gateway_method.isolated_method.http_method
+  status_code = "500"
+
+  response_models = {
+    "application/json" = aws_api_gateway_model.error_model.name
+  }
+}
+
+# Isolated OPTIONS (CORS)
+resource "aws_api_gateway_method" "isolated_options_method" {
+  rest_api_id   = aws_api_gateway_rest_api.api_gateway.id
+  resource_id   = aws_api_gateway_resource.isolated_resource.id
+  http_method   = "OPTIONS"
+  authorization = "NONE"
+}
+
+resource "aws_api_gateway_integration" "isolated_options_integration" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.isolated_resource.id
+  http_method = aws_api_gateway_method.isolated_options_method.http_method
+  type        = "MOCK"
+
+  request_templates = {
+    "application/json" = "{\"statusCode\": 200}"
+  }
+}
+
+resource "aws_api_gateway_method_response" "isolated_options_response_200" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.isolated_resource.id
+  http_method = aws_api_gateway_method.isolated_options_method.http_method
+  status_code = "200"
+
+  response_parameters = {
+    "method.response.header.Access-Control-Allow-Headers" = true
+    "method.response.header.Access-Control-Allow-Methods" = true
+    "method.response.header.Access-Control-Allow-Origin"  = true
+  }
+}
+
+resource "aws_api_gateway_integration_response" "isolated_options_integration_response" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+  resource_id = aws_api_gateway_resource.isolated_resource.id
+  http_method = aws_api_gateway_method.isolated_options_method.http_method
+  status_code = aws_api_gateway_method_response.isolated_options_response_200.status_code
+
+  response_parameters = {
+    "method.response.header.Access-Control-Allow-Headers" = "'Content-Type,X-Amz-Date,Authorization,X-Api-Key,X-Amz-Security-Token,x-tenant-id'"
+    "method.response.header.Access-Control-Allow-Methods" = "'GET,OPTIONS'"
+    "method.response.header.Access-Control-Allow-Origin"  = "'*'"
+  }
+
+  response_templates = {
+    "application/json" = ""
+  }
+}
+
+# ──────────────────────────────────────────────
+# Lambda Permissions for API Gateway
+# ──────────────────────────────────────────────
+
+resource "aws_lambda_permission" "standard_function_permission" {
+  statement_id  = "AllowAPIGatewayInvoke"
+  action        = "lambda:InvokeFunction"
+  function_name = aws_lambda_function.counter_standard_function.function_name
+  principal     = "apigateway.amazonaws.com"
+  source_arn    = "${aws_api_gateway_rest_api.api_gateway.execution_arn}/*/*"
+}
+
+resource "aws_lambda_permission" "isolated_function_permission" {
+  statement_id  = "AllowAPIGatewayInvoke"
+  action        = "lambda:InvokeFunction"
+  function_name = aws_lambda_function.counter_isolated_function.function_name
+  principal     = "apigateway.amazonaws.com"
+  source_arn    = "${aws_api_gateway_rest_api.api_gateway.execution_arn}/*/*"
+}
+
+# ──────────────────────────────────────────────
+# API Gateway Deployment & Stage
+# ──────────────────────────────────────────────
+
+resource "aws_api_gateway_deployment" "api_gateway_deployment" {
+  rest_api_id = aws_api_gateway_rest_api.api_gateway.id
+
+  triggers = {
+    redeployment = sha1(jsonencode([
+      aws_api_gateway_resource.standard_resource.id,
+      aws_api_gateway_method.standard_method.id,
+      aws_api_gateway_integration.standard_integration.id,
+      aws_api_gateway_resource.isolated_resource.id,
+      aws_api_gateway_method.isolated_method.id,
+      aws_api_gateway_integration.isolated_integration.id,
+    ]))
+  }
+
+  lifecycle {
+    create_before_destroy = true
+  }
+
+  depends_on = [
+    aws_api_gateway_method.standard_method,
+    aws_api_gateway_integration.standard_integration,
+    aws_api_gateway_method.standard_options_method,
+    aws_api_gateway_integration.standard_options_integration,
+    aws_api_gateway_method.isolated_method,
+    aws_api_gateway_integration.isolated_integration,
+    aws_api_gateway_method.isolated_options_method,
+    aws_api_gateway_integration.isolated_options_integration,
+  ]
+}
+
+resource "aws_api_gateway_stage" "api_gateway_stage" {
+  deployment_id = aws_api_gateway_deployment.api_gateway_deployment.id
+  rest_api_id   = aws_api_gateway_rest_api.api_gateway.id
+  stage_name    = var.environment
+  description   = "[${var.prefix}] Stage for ${var.environment} environment"
+
+  tags = {
+    Environment = var.environment
+    Prefix      = var.prefix
+  }
+}
+
+# ──────────────────────────────────────────────
+# Outputs
+# ──────────────────────────────────────────────
+
+output "prefix_used" {
+  description = "The prefix used for all resources"
+  value       = var.prefix
+}
+
+output "standard_lambda_function_name" {
+  description = "Standard Lambda function name"
+  value       = aws_lambda_function.counter_standard_function.function_name
+}
+
+output "isolated_lambda_function_name" {
+  description = "Isolated Lambda function name"
+  value       = aws_lambda_function.counter_isolated_function.function_name
+}
+
+output "dynamodb_shared_counter_table_name" {
+  description = "DynamoDB table for shared counters"
+  value       = aws_dynamodb_table.shared_counter_table.name
+}
+
+output "dynamodb_isolated_counter_table_name" {
+  description = "DynamoDB table for isolated per-tenant counters"
+  value       = aws_dynamodb_table.isolated_counter_table.name
+}
+
+output "api_gateway_id" {
+  description = "API Gateway REST API ID"
+  value       = aws_api_gateway_rest_api.api_gateway.id
+}
+
+output "standard_multi_tenant_api_endpoint_url" {
+  description = "URL for the standard Lambda function endpoint"
+  value       = "${aws_api_gateway_stage.api_gateway_stage.invoke_url}/standard"
+}
+
+output "isolated_tenant_api_endpoint_url" {
+  description = "URL for the tenant-isolated Lambda function endpoint"
+  value       = "${aws_api_gateway_stage.api_gateway_stage.invoke_url}/isolated"
+}
\ No newline at end of file