AWS Lambda durable functions

Build resilient multi-step applications and AI workflows that can execute for up to 1 year while maintaining reliable progress despite interruptions.

Works best with the AWS MCP server but is not required. All AWS interactions in this skill use standard AWS CLI commands that work in any environment with configured AWS credentials.

Critical Rules

Read these before writing any code. Each one is a constraint that will silently break a function if violated.

1. Durable execution must be enabled at function creation time — it cannot be retrofitted. A new Lambda function must be created with durable execution turned on. Migrate the logic into the new function; do not attempt to install the SDK and wrap the handler of the existing function and expect it to work.
2. Durable functions must be invoked with a qualified ARN — a specific version, an alias, or the literal $LATEST suffix. An unqualified function name will fail. See the Invocation Requirements section below for examples.
3. Durable operations cannot be nested. You cannot call context.step(), context.wait(), or context.invoke() from inside another step's callback. Use context.runInChildContext() to group operations instead.
4. All non-deterministic code must run inside steps. Date.now(), Math.random(), UUID generation, API calls, and database queries outside a step will produce different values on replay and corrupt execution state.
5. Closure mutations are lost on replay - return values from steps
6. Side effects outside steps repeat - use context.logger (replay-aware)

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