AWS Lambda best practices for function design, configuration, and operations. Use when designing Lambda functions, choosing memory/timeout settings, planning concurrency and scaling, setting up monitoring, processing streams, or securing Lambda workloads. Triggers on tasks involving Lambda function creation, handler design, cold start optimization, idempotency, event source mapping, reserved/provisioned concurrency, or deciding whether Lambda is the right compute choice. Does not cover language-specific SDK patterns, CloudFormation/Terraform resource definitions, or Lambda@Edge.